Non-Ferrous Smelter, Lead, Zinc, Copper, Tin Refining and Nickel Laterite Manufacturing HVAC Duct Guide — Port Pirie, Mount Isa, Townsville, Hobart, Kwinana, Kalgoorlie, Ravensthorpe, Renison Bell

1. Why non-ferrous smelter HVAC is its own engineering discipline

The Australian non-ferrous metals industry is one of the most chemically diverse heavy industrial sectors in the country. Five operating primary smelters or refineries — Nyrstar Port Pirie at Port Pirie SA (world's largest lead smelter, around 240,000 t/yr Pb plus zinc, silver, copper and gold by-products, operating the Top-Submerged Lance TSL pyrometallurgical route since the Port Pirie Smelter Transformation Programme completed), Glencore Mount Isa Copper Smelter at Mount Isa QLD (around 200,000 t/yr anode copper, operating the ISASMELT TSL route originally developed at this site through the joint venture with the former CSIRO heat-and-mass-transfer group), Glencore Townsville Copper Refinery at Stuart QLD (electrorefining of Mount Isa anode copper to LME Grade A cathode, around 300,000 t/yr Cu cathode), Sun Metals zinc refinery at Stuart QLD (around 250,000 t/yr Zn, operating the Electrolytic Zinc EZ process on Century-derived and imported zinc concentrate), and Nyrstar Hobart zinc smelter at Risdon TAS (around 280,000 t/yr Zn, also EZ process and the oldest continuous zinc operation in Australia, in production since 1917) — collectively produce around 1.07 Mt/yr of refined non-ferrous metal, consume more than 5 percent of the National Electricity Market load between them, and operate the largest installed base of sulfuric acid plants in Australia (with a combined H2SO4 capacity north of 2.5 Mt/yr from captured smelter SO2 off-gas).

Adjacent nickel operations are in transition. BHP Kwinana Nickel Refinery at Kwinana WA (around 65,000 t/yr Ni metal product as briquette and powder, operating the Sherritt-Gordon ammoniacal leach route on Mount Keith and Leinster nickel sulfide concentrate) continues to operate as the downstream refining endpoint of BHP's Nickel West business; BHP Kalgoorlie Nickel Smelter at Kambalda WA (historically around 100,000 t/yr Ni in matte, smelting the same concentrate before refining at Kwinana) is in the process of decommissioning through 2024 as BHP transitions its nickel position in response to global market conditions; First Quantum Minerals Ravensthorpe Nickel at Ravensthorpe WA (around 30,000 t/yr Ni as mixed hydroxide product MHP, operating the High-Pressure Acid Leach HPAL route on limonitic laterite ore) restarts and ramps back up through 2025–26 after a period of care and maintenance; and a portfolio of advanced-stage Australian nickel sulfide development projects (Avebury at Tasmania under Mallee Resources, Black Range Wingellina, and various WA projects) sit behind a market wall of constrained nickel pricing and uncertain Indonesian competition.

Tin is a smaller but specialised position. Renison Bell on the west coast of Tasmania (operated by Metals X subsidiary Bluestone Mines Tasmania Joint Venture, around 8,500 t/yr Sn-in-concentrate at the recent operating tempo, with concentrate exported offshore for smelting because Australia no longer operates a domestic primary tin smelter since the closure of the Greenbushes Tin Smelter in WA in the 1990s) is the principal Australian tin source. The HVAC scope at Renison Bell is concentrator-focused — flotation, dryer, concentrate handling — rather than primary smelting.

The combined HVAC load across this value chain is enormous, and it is fundamentally different from the iron, steel and aluminium scopes covered in our companion guides. Where a steel mill's HVAC challenge is dominated by sheer flue volume and primary off-gas temperature, and where an aluminium smelter's challenge is dominated by fluorine chemistry on the smelter side and caustic on the refinery side, a non-ferrous smelter's challenge is dominated by sulfur dioxide. SO2 from galena roasting (Port Pirie), SO2 from sphalerite roasting (Sun Metals, Hobart), SO2 from chalcopyrite smelting (Mount Isa), SO2 from pentlandite smelting (Kalgoorlie historically), SO2 from pyrite combustion in the acid plant (Kwinana). Every primary smelter in the Australian non-ferrous portfolio has a captive contact sulfuric acid plant on the back end, and every single one of those acid plants runs 316L stainless steel ductwork from the converter exit to the stack discharge.

Underneath that single dominant chemistry sits a portfolio of secondary chemistries that each drive their own duct specification. Arsenic trioxide (As2O3) condensation from broken Hill lead concentrate; cadmium fume from sphalerite roasting; lead-bearing dust at every concentrate transfer point; hydrogen fluoride trace contamination from fluoride-bearing copper concentrates; carbon monoxide from incomplete combustion in the converter aisle; ammonia from the Sherritt-Gordon leach at Kwinana; hydrogen sulfide from xanthate decomposition in flotation; carbon disulfide CS2 trace at the flotation circuit; nitrogen oxides NOx from nitric acid leach in some hydromet circuits. Each of these contaminants has its own Safe Work Australia Workplace Exposure Standard, and the cumulative engineering challenge is to manage all of them simultaneously while maintaining production tempo against world-traded commodity benchmarks.

Seven characteristics make non-ferrous smelter HVAC its own discipline. First, the corrosion environment is dominated by sulfuric acid in every form — gas-phase SO2, gas-phase SO3, aerosol H2SO4 mist, condensed H2SO4 liquor, and dilute H2SO4 carry-over from the cellhouse — and 316L molybdenum-stabilised austenitic stainless is the workhorse material across every cold-side leg. Second, the metallurgical fume environment includes arsenic, cadmium, lead, antimony, bismuth, tellurium, selenium and mercury at trace-to-percent levels, each of which has a stringent Safe Work Australia WES and each of which condenses preferentially on cooler duct surfaces, creating cumulative deposits that demand routine inspection and clean-out programmes. Third, the temperature gradient at the primary smelter is extreme — molten matte and slag at 1,150–1,300°C, primary off-gas at the hood at 1,000–1,200°C, waste heat boiler exit at 350–450°C, ESP outlet at 250–350°C, scrubbed gas at the acid plant converter at 400°C catalyst-bed temperature, absorption tower at 70–90°C — and the duct system must accommodate the full thermal swing with appropriate material transitions and expansion joints. Fourth, the acid plant gas train itself is one of the largest single HVAC scope items on the project, with 15–25 km of 316L stainless duct between ESP and stack on a typical 200,000 t/yr non-ferrous smelter acid plant. Fifth, the cellhouse — copper electrorefining at Townsville, zinc electrowinning at Sun Metals and Hobart, nickel electrowinning at Kwinana — generates sulfuric acid mist that demands its own dedicated extract and scrubbing scope, with operator-zone WES of 0.2 mg/m³ H2SO4 driving the engineering design. Sixth, the operator working environment is severe — pot tappers, matte tappers, anode setters, anode strippers, cellhouse linesmen all work within metres of molten metal or live electrolyte at elevated current density, in summer ambient temperatures that exceed 40°C at Port Pirie, Mount Isa, Townsville and Kwinana — and operator pulpit cooling, crane cabin air-conditioning and refrigerated spot-cooling are mandatory engineering controls under Safe Work Australia heat-stress guidance. Seventh, the electrical infrastructure is significant — every copper, zinc and nickel cellhouse draws DC current at 30–50 kA per circuit, and the rectifier substations have transformer-cooling and switchgear-room HVAC loads that mirror the aluminium smelter scope.

This guide walks the complete non-ferrous value chain from concentrate receival through smelting, converting, refining, anode casting, cellhouse electrorefining or electrowinning, acid plant, cast house and shipping, explains what changes at each station from an HVAC ductwork perspective, and identifies where SBKJ standard machinery covers the scope and where heavy welded refractory-lined fabrication takes over. We have shipped SBKJ duct fabrication machinery to fabricators serving non-ferrous projects in Australia, Africa, South America and the Middle East since the late 1990s, and the recurring theme is the same: the project economics live or die on whether the fabricator can run 316L stainless reliably at production tempo, with seam integrity good enough to pass leakage testing under AS 4254 high-pressure construction the first time and with passivation good enough to survive a 15-year acid plant operating cycle without pitting initiation in the heat-affected zone.

2. The Australian regulatory stack — AS 1668.2, AS 4254, AS/NZS 60079, NFPA 660, NFPA 850, NFPA 86 and Safe Work Australia WES

Non-ferrous smelter HVAC in Australia sits at the intersection of more regulatory documents than almost any other industrial sector outside the aluminium value chain. The compliance question on every project is not whether one standard applies — they all apply — but how the layered requirements interact across the primary smelter, the converter aisle, the acid plant, the cellhouse, the operator pulpit and the stack discharge.

2.1 AS 1668.1 — fire and smoke control

AS 1668.1:2015 (The use of ventilation and airconditioning in buildings — Fire and smoke control) sets the smoke-spill and stair-pressurisation requirements for the building services HVAC. In a non-ferrous smelter or refinery this drives the duct fire rating in the control room, switchgear room, battery room and cable trench corridors. The standard requires fire-rated duct construction (typically rated to AS 1530.4 for 60/60/60 minutes minimum, stepping to 120/120/120 minutes in critical egress routes) and fire dampers at every fire-rated wall penetration with AS 1851 routine service maintenance.

2.2 AS 1668.2 — mechanical ventilation

AS 1668.2:2012 (Mechanical ventilation in buildings — Mechanical ventilation for acceptable indoor-air quality) sets the building-services baseline for occupied spaces. In a non-ferrous smelter this drives the outdoor-air rate at every pulpit, crane cabin, control room, electrical room, laboratory, amenity block, weighbridge office and administration building. The standard requires 10 L/s per occupant minimum outdoor air for typical office and control-room occupancy, with higher rates for change rooms, showers, toilets and kitchens. Where AS 1668.2 matters most on a smelter project is the pulpit pressurisation requirement: it sets the engineering basis for the 25–50 Pa positive pressure that prevents converter aisle SO2, As2O3 fume and lead-bearing dust from migrating into the operator cabin. The make-up air requirement layered on top of LEV — every cubic metre extracted from a converter aisle, a tap floor or a cellhouse must be balanced by tempered outdoor make-up air — drives total smelter HVAC ductwork volume up significantly compared with a building of equivalent floor area but no process exhaust.

2.3 AS 4254 — ductwork construction

AS 4254.1 (Flexible ductwork) and AS 4254.2 (Rigid ductwork) are the Australian duct construction standards that govern gauge, joint type, pressure class and reinforcement spacing. For non-ferrous smelter HVAC the typical pressure class is medium-pressure on supply and return runs (up to 750 Pa static), high-pressure on the acid plant gas train and cellhouse mist extract (up to 2,500 Pa static), and ultra-high-pressure on the negative side of the ID fan upstream of the stack on the acid plant final absorption tower. The standard sets out the leakage class requirements (Class A, B, C) that drive the fabrication tolerance — SMACNA Class B equivalent for general HVAC, Class C for acid plant and cellhouse-side ducting where leakage of corrosive gas to the surrounding building is unacceptable. AS 4254.2 also drives the duct joint specification: TDF (T-Drive Flange) or AS angle flange for galvanised and 304L medium-pressure; continuous seam-welded flange or full-perimeter gasket compression for 316L acid-side high-pressure.

2.4 AS 1530.4 — fire-resistant ductwork

AS 1530.4 (Methods for fire tests on building materials, components and structures) classifies fire-resistant duct construction for smoke-spill and stair-pressurisation duty. Non-ferrous smelters have significant fire-load zones — concentrate storage with petroleum-based collector reagent residues, anode casting wheel area with molten metal, cable trench beneath rectifier substations, LPG fuel-supply rooms for refining furnaces, solvent extraction (SX) building with kerosene-based diluent — and the duct passing through these zones must be rated for the specified fire-resistance level (typically 60/60/60 to 120/120/120 minutes of structural integrity, insulation and integrity).

2.5 AS/NZS 60079 — hazardous-area classification

AS/NZS 60079 (Explosive atmospheres) and the underlying IEC 60079 series classify hazardous areas where flammable gas, vapour or combustible dust can reach explosible concentration. Non-ferrous smelters have multiple Zone classifications: Zone 1 (gas, present in normal operation) around hydrogen sulfide H2S generation points in xanthate flotation, around ammonia at the Sherritt-Gordon leach plant, around carbon disulfide CS2 at flotation reagent storage; Zone 2 (gas, present only abnormally) around LPG-fired refining furnace and anode bake fuel-supply trenches; Zone 21 (dust, present in normal operation) around concentrate handling, sinter strand and roasting; Zone 22 (dust, present only abnormally) around anode storage and cathode strip stations. The classification drives Ex-rated electrical equipment requirements for fans, motors, instrumentation, lighting and switchgear, and it drives bonding and grounding of every duct segment to prevent static-discharge ignition of combustible dust. AS/NZS 60079.10.1 and .10.2 cover the gas and dust zoning respectively.

2.6 AS 4360 — risk management

AS 4360 (Risk management), now incorporated into AS/NZS ISO 31000, drives the formal hazard analysis at every smelter project. The HAZOP (Hazard and Operability Study), LOPA (Layer of Protection Analysis) and SIL (Safety Integrity Level) assessments for the acid plant, the converter aisle and the cellhouse are mandatory deliverables on every non-ferrous smelter project under the WHS Act 2011 and the relevant state mining or workplace health and safety regulator (SafeWork SA for Port Pirie, Queensland Resources Safety and Health for Mount Isa and Townsville, WorkSafe Tasmania for Hobart and Renison Bell, DMIRS for Kwinana, Kalgoorlie and Ravensthorpe).

2.7 AS/NZS 2107 — acoustics

AS/NZS 2107 (Acoustics — Recommended design sound levels and reverberation times for building interiors) drives the acoustic design of the operator pulpit, crane cabin, control room and amenity block. Smelter background sound pressure level routinely exceeds 90 dB(A) in the converter aisle and 95 dB(A) at the cellhouse cell shorting frequency — pulpit design targets 50 dB(A) interior sound pressure level under AS/NZS 2107 office criteria, requiring acoustic-rated AHU plenums, lined supply duct, attenuators and gasket-sealed pulpit shell construction.

2.8 AS/NZS 3000 — wiring rules

AS/NZS 3000 (Electrical installations — Wiring Rules) drives the electrical installation of every fan motor, every damper actuator, every variable speed drive and every duct-mounted instrument. Where the HVAC system passes through a hazardous-area zone the wiring is Ex-rated per AS/NZS 60079.14; in non-hazardous zones the wiring follows the standard cable selection, segregation and earthing rules of AS/NZS 3000.

2.9 NFPA 660 — combustible dust

NFPA 660 (Standard for Combustible Dusts), which consolidated NFPA 484, NFPA 652, NFPA 654, NFPA 655, NFPA 664 and NFPA 61 into a single combined standard from 2025, is the de-facto engineering reference for combustible-dust handling globally and is referenced extensively by Australian non-ferrous-industry insurance underwriters (FM Global, Zurich, QBE). The standard mandates a written Dust Hazard Analysis (DHA) at every dust-handling step, deflagration venting or chemical suppression on bag filters and cyclones, isolation dampers between the baghouse and the upstream duct trunk to prevent flame propagation, bonded and grounded duct construction with electrical continuity verified by bonding test, spark-resistant fan construction per AMCA 99-0401, and Ex-rated electrical equipment in the dust zone. On Australian non-ferrous plants NFPA 660 applies to the concentrate handling and drying area, the sinter strand at Port Pirie, the green anode and butt cleaning at copper smelters, the cellhouse busbar and rectifier area, and the cast house aluminium dust capture in the anode rod-up shop.

2.10 NFPA 850 — fire protection for power generation and DC converter stations

NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations), originally drafted for power station fire protection, is referenced extensively for the rectifier substation, DC bus and cellhouse electrical fire-protection design on non-ferrous smelter projects. The companion NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems) is relevant for the increasing use of battery energy storage to firm the cellhouse load profile. NFPA 850 drives gas-tight cable-trench ducting with smoke detection and inergen or FM-200 chemical suppression, transformer hall ventilation sized to handle a worst-case oil-mist release, switchgear room positive pressurisation to keep dust out, and battery room ventilation per IEEE 484 for the DC backup systems.

2.11 NFPA 86 — industrial ovens and furnaces

NFPA 86 (Industrial Ovens and Furnaces) governs the gas-fired refining furnace, anode bake furnace, holding furnace, slag fuming furnace and any LPG-fired oven inside the non-ferrous plant. It dictates the exhaust topology — lower explosive limit (LEL) monitoring on combustion air, purge cycles before lighting, explosion venting on the oven shell, dedicated stack risers separate from general extract, and fuel-piping segregation from the building service main.

2.12 Safe Work Australia Workplace Exposure Standards

The Safe Work Australia Workplace Exposure Standards for Airborne Contaminants set the legal upper limit for operator exposure. The relevant entries for non-ferrous smelter operations are: inorganic lead 0.05 mg/m³ TWA (with biological monitoring 30 µg/dL blood lead for adult males, 10 µg/dL women of reproductive age); inorganic arsenic 0.05 mg/m³ TWA (As); cadmium 0.01 mg/m³ TWA (Cd); copper fume 0.2 mg/m³ TWA, copper dust 1 mg/m³ TWA; zinc oxide fume 5 mg/m³ TWA, zinc oxide dust 10 mg/m³ TWA inhalable; nickel as inorganic compounds 0.1 mg/m³ TWA, nickel metal 1 mg/m³, nickel carbonyl 0.05 ppm TWA; tin inorganic 2 mg/m³ TWA, organotin 0.1 mg/m³; sulfur dioxide 2 ppm TWA, 5 ppm STEL; carbon monoxide 30 ppm TWA, 200 ppm STEL; hydrogen sulfide 10 ppm TWA, 15 ppm STEL; sulfuric acid mist 0.2 mg/m³ thoracic fraction TWA; ammonia 25 ppm TWA, 35 ppm STEL; chromium VI (relevant to legacy smelter operations using chromium-bearing mist suppressants) 0.05 mg/m³ TWA; antimony as Sb 0.5 mg/m³ TWA; bismuth 5 mg/m³ TWA; tellurium 0.1 mg/m³ TWA; selenium 0.2 mg/m³ TWA; mercury vapour 0.025 mg/m³ TWA. These limits drive the engineering controls at every hood capture point, every duct connection, every fan and stack discharge, and every operator pulpit make-up air supply.

2.13 The International Lead Zinc Research Organisation and the Nickel Institute

The International Lead Zinc Research Organisation (ILZRO), the International Copper Association (ICA) and the Nickel Institute publish good-practice guides on smelter fume control, acid plant design, cellhouse mist control and ductwork material selection that inform Australian non-ferrous operations. The Australian Workers' Union and the Construction Forestry Maritime Mining and Energy Union (CFMMEU) actively participate in operator-health forums at Port Pirie, Mount Isa and Townsville, and union representation drives many of the operator-side engineering controls (pulpit pressurisation, respirator programmes, blood-lead monitoring) that the formal regulatory stack endorses.

3. Concentrate handling, drying and storage

The non-ferrous value chain starts at the concentrate receival yard. For Nyrstar Port Pirie this is the lead concentrate from Broken Hill (CBH Resources Rasp Mine), McArthur River (Glencore), Cannington (South32, world's largest single silver-lead mine) and historical imports through Port Adelaide. For Glencore Mount Isa the copper concentrate is sourced from Mount Isa Copper's own underground mines (X41, U62, Black Star, Enterprise) plus regional third-party feedstock. For Glencore Townsville the anode copper from Mount Isa arrives by rail (the historic 977 km North West rail line from Mount Isa to Townsville). For Sun Metals the zinc concentrate is sourced from Century Zinc (now MMG/Pasminco legacy, restart by New Century Resources), Mount Isa (Glencore), Cannington (silver-lead-zinc by-product), Endeavor (Polymetals legacy), Lady Loretta (Glencore) and imports through Port of Townsville. For Nyrstar Hobart the zinc concentrate is sourced from a similar portfolio plus imports through the Port of Hobart and rail-and-road to Risdon.

HVAC scope at the concentrate yard is dominated by dust extract. Concentrate is typically 8–15 percent free moisture as received, and the warehouse and bin-store ventilation must handle the airborne fines released during truck tip, conveyor transfer, sampling and bin discharge. Safe Work Australia WES for the metal-bearing dust is the worst-case of the constituent metals — lead at 0.05 mg/m³ TWA dominates for lead concentrate, cadmium at 0.01 mg/m³ TWA for zinc concentrate (cadmium-bearing sphalerite at 0.1–0.3 percent Cd), arsenic at 0.05 mg/m³ for arsenic-bearing copper concentrate. The capture velocity at hood is 0.5–1.0 m/s and the conveying velocity in the dust main is 18–22 m/s to keep solids in suspension.

Concentrate drying is required upstream of fluid bed roasting (zinc) and upstream of TSL/ISASMELT smelting (lead and copper). Rotary dryers operating at 200–400°C reduce free moisture from 8–15 percent to 2–5 percent before furnace feed. The dryer exhaust carries fine concentrate dust at 5–20 g/Nm³ before the bag filter, plus combustion products (CO2, H2O, NOx, residual SO2 from the small amount of sulfide oxidation during drying), and significant water vapour. Material selection on the dryer side is mild steel with paint corrosion allowance for the cold side and refractory-lined steel for the hot section near the dryer outlet. The bag filter is sized for 1–2 m/min air-to-cloth ratio with PTFE-membrane bags rated for the dust loading.

Duct material at concentrate handling is typically galvanised carbon steel for the cold-side dust mains, with abrasion-resistant linings (chromium-carbide overlay or ceramic-bead lining) at elbows and tee-junctions. The high-velocity transport duct at 18–22 m/s wears measurably at every change of direction, and the elbow life on unlined duct in lead and copper concentrate service is 12–24 months versus 5–7 years for lined elbows.

SBKJ SBAL-V and SBTF cover the cold-side galvanised dust mains and the building-services HVAC at the concentrate yard, sampling tower, dryer building, control room, electrical room, workshop and amenity blocks. The SBFB-1500 spiral duct line is the workhorse for round duct in this scope. Abrasion-resistant ducting is procured separately from specialist wear-plate fabricators. SBKJ spark-resistant fan supply covers the concentrate handling extract per NFPA 660 — concentrate itself is not combustible but iron-oxide tramp metal and organic collector reagent residue drive the spark-resistant fan specification on every concentrate-handling baghouse.

4. Lead smelter — Nyrstar Port Pirie and the TSL Top-Submerged Lance route

Nyrstar Port Pirie is the world's largest single lead smelter. The site has operated continuously at Port Pirie SA since 1889 (then under the Broken Hill Associated Smelters BHAS banner, succeeded through Pasminco and now Nyrstar under Trafigura ownership), and the recent Port Pirie Smelter Transformation Programme (PPSTP) completed in the late 2010s replaced the legacy sinter-blast furnace route with a modern Top-Submerged Lance (TSL) furnace plus electric slag-fuming furnace and dedicated sulfuric acid plant. The transformation reduced lead emissions to the boundary, improved energy efficiency, and brought the smelter into compliance with the Port Pirie Environmental Protection (Air Quality) Policy and the SA EPA Environmental Authorisation conditions.

4.1 Sinter strand and concentrate roasting (legacy and current)

In the legacy sinter-blast furnace route the lead concentrate (galena PbS plus sphalerite ZnS plus pyrite FeS2 plus minor minerals) was first sintered on a Dwight-Lloyd updraft sinter machine, oxidising the sulfide to oxide and releasing SO2 to the acid plant. The sinter strand HVAC scope was — and at residual operations continues to be — one of the most demanding in the Australian non-ferrous portfolio: gas at 400–600°C, lead-bearing dust at 5–15 g/Nm³, SO2 at 4–8 percent by volume, arsenic and antimony fume from the As2O3 and Sb2O3 volatilised at sinter strand temperature, and high moisture from the sinter strand water sprays. The hood and ductwork from sinter strand to ESP is refractory-lined carbon steel; from ESP outlet to acid plant the duct is 316L stainless throughout. In the modern PPSTP configuration the sinter strand is reduced or replaced by the TSL feed system, but the underlying chemistry remains.

4.2 Top-Submerged Lance (TSL) furnace

The TSL furnace is the heart of the modern Port Pirie smelter. A vertical cylindrical furnace with a steel shell lined with refractory brick, the TSL is fed lead-bearing material (concentrate, sinter, recycled flue dust, fume, secondary feed) at the top, combusts with oxygen-enriched air injected through a submerged lance, and produces molten lead bullion at the tap and slag at a higher level. The lance is the eponymous feature — a vertical steel pipe lowered through the roof into the slag layer, with combustion air injected at the bottom to mix and oxidise the bath. Combustion temperature 1,200–1,300°C, off-gas at the hood 1,000–1,100°C carrying SO2 at 8–18 percent by volume, lead-bearing fume at 10–30 g/Nm³ before the waste heat boiler, arsenic and antimony fume, and residual carbon monoxide from the reducing-end of the bath cycle.

HVAC scope on the TSL hood is heavy welded refractory-lined carbon steel from the furnace mouth to the waste heat boiler inlet, sized for the worst-case off-gas flow (typically 80,000–150,000 Nm³/h on a 240,000 t/yr Pb smelter), with expansion joints for the thermal transient at every tap and feed cycle. The waste heat boiler recovers steam at the elevated pressure (the Port Pirie boiler integrates with the acid plant utility steam ring main). After the boiler the gas is at 350–450°C and the duct transitions to 309S/310S stainless or refractory-lined carbon steel through to the ESP inlet, then to 316L stainless from the ESP outlet through the acid plant gas train to the stack.

4.3 Slag-fuming furnace

The slag from the TSL still contains valuable zinc, lead and other metals. A dedicated slag-fuming furnace (electric arc or fuel-fired) volatilises the residual zinc as ZnO fume, which is captured in a baghouse and recycled either to the TSL (in-house) or sold as zinc oxide product. The slag-fuming hood and ductwork is heavy welded refractory-lined carbon steel from furnace to baghouse, with 316L stainless cold-side scope from the baghouse outlet through the ID fan to the stack. Material on the cold side runs at 130–180°C with residual SO2 and water vapour from combustion — classic 316L acid-condensing service.

4.4 Refining kettles and refining furnaces

The lead bullion from the TSL contains valuable impurities — silver, gold, copper, antimony, bismuth, tellurium, selenium — that are recovered in a series of refining kettles. The Parkes process removes silver and gold using zinc; the Harris process removes antimony, arsenic, tin and bismuth using NaOH and sodium nitrate; the Betterton-Kroll process recovers bismuth using calcium and magnesium. Each kettle is a fuel-fired or electric-heated open-top vessel at 400–600°C, with a roof hood for fume capture.

The kettle hood extract is one of the most chemically diverse HVAC scopes in Australian heavy industry — depending on the refining stage the fume can contain lead oxide, silver, gold, antimony oxide, arsenic trioxide, bismuth oxide, tellurium, selenium, and the alkali fume from Harris process NaOH addition. Material is 316L stainless throughout, with HEPA secondary filtration on the bag filter to capture the very fine sub-micron metallic fume. The recovered fume is processed in a dedicated by-product recovery building.

4.5 Anode casting wheel

The refined lead is cast on a rotary casting wheel (Currie wheel or equivalent) into ingot or jumbo blocks for shipping. The casting wheel hood extracts the lead oxide fume from the molten lead surface (Pb fume volatility increases sharply above 600°C and is significant at the 400–500°C casting temperature). Material is 316L stainless for the hood and duct; the fume is recovered in a small dedicated baghouse and recycled to the smelter.

4.6 Lead-bearing dust handling

Throughout the smelter the fume and flue dust collected at every baghouse is itself a valuable feedstock — typically 30–60 percent Pb plus other metals. The dust handling building has its own dedicated HVAC scope: pneumatic transport or screw conveyor from baghouse hopper to dust silo, dust silo top dome hood extract, dust feed to TSL or to dedicated dust roasting, and bagging-off for spent baghouse media disposal. Material is 316L stainless throughout for the lead-bearing dust streams, and the dust transport is under HEPA-filtered air per the Safe Work Australia lead WES of 0.05 mg/m³ TWA.

4.7 Sulfuric acid plant — Port Pirie

The Port Pirie acid plant captures the SO2 from the TSL, slag-fuming furnace and any residual sinter strand into a contact sulfuric acid plant of around 200,000–250,000 t/yr H2SO4 capacity. The gas train: ESP outlet → drying tower (98–99 percent H2SO4) → SO2 blower → catalyst beds (Bed 1 to Bed 4 with intermediate cooling and interpass absorption) → final absorption tower → stack. Total duct length on the acid plant gas train is 12–18 km, all 316L stainless. Material thickness 1.5–3.0 mm depending on size and pressure class; flanging AS 4254 high-pressure with chemical-resistant gasket; demisters at the drying tower top and absorption tower top to keep H2SO4 mist out of the downstream duct.

SBKJ SBAL-V auto duct line in 316L mode handles the cold-side acid plant duct up to the 1.5 mm × 1,500 mm rectangular envelope. The SBFB-1500 spiral duct line is the workhorse for the round duct between drying tower and converter and around the interpass absorption. The SBSF-1525 stitchwelder provides the continuous seam welding for the flanging and the SB-ZF1500 covers the larger continuous seam joints on the absorption tower duct. The SBPC1500 plasma cutter cuts saddle connections, take-offs and access door openings in 316L. The SBLR-600 site welder covers the field joins between shop-fabricated segments.

5. Copper smelter — Glencore Mount Isa and the ISASMELT route

Glencore Mount Isa Copper Smelter is the largest operating copper smelter in Australia. The ISASMELT TSL technology was developed at Mount Isa through a joint CSIRO–Mount Isa Mines collaboration in the 1980s and has been licensed globally; the Mount Isa smelter itself runs the technology on its own copper concentrate (chalcopyrite CuFeS2 plus minor bornite and chalcocite) from the Mount Isa Copper underground mines (X41, U62, Black Star, Enterprise).

5.1 ISASMELT primary smelter

The ISASMELT furnace is structurally identical to the TSL at Port Pirie — vertical cylindrical refractory-lined furnace with submerged lance combustion air injection — but it operates at slightly different conditions for copper: 1,180–1,220°C bath temperature, oxygen-enriched air at 50–65 percent O2, off-gas at the hood 1,050–1,150°C carrying SO2 at 10–18 percent by volume, copper-bearing fume at 5–20 g/Nm³ before the waste heat boiler, and a matte product at 60–65 percent Cu that taps to a holding furnace.

HVAC scope on the ISASMELT primary hood is heavy welded refractory-lined carbon steel from the furnace mouth to the waste heat boiler inlet, sized for the worst-case off-gas flow (typically 70,000–120,000 Nm³/h on a 200,000 t/yr Cu smelter), with expansion joints for thermal transients. The waste heat boiler recovers steam. After the boiler the gas at 350–450°C transitions to 309S/310S then to 316L stainless from the ESP outlet through the acid plant.

5.2 Peirce-Smith (PS) converter aisle

The matte from the ISASMELT is converted to blister copper in a Peirce-Smith (PS) horizontal cylindrical converter. The PS converter is the classic copper smelter converter — a horizontal cylindrical vessel that rotates to a charging position for matte and slag, then rotates to a blowing position where oxygen-enriched air is injected through tuyeres along the side, oxidising the iron sulfide in the matte to FeO (which slags) and oxidising the copper sulfide partially to Cu2S (white metal) and then to blister copper (98+ percent Cu). The blowing cycle is intermittent — the converter rotates back to charging for each fresh matte addition — and the off-gas chemistry varies wildly during the blow.

The PS converter hood is one of the most challenging HVAC environments in non-ferrous smelting. The hood is positioned over the converter mouth and must capture the off-gas during all rotation positions and during the open-mouth charging and skimming. Capture efficiency on a well-designed PS converter hood is 90–95 percent; the remaining 5–10 percent escapes to the building extract as fugitive emission. The captured gas is taken to a primary off-gas baghouse and then merged with the ISASMELT gas stream in the acid plant. Material on the hood is refractory-lined carbon steel for the high-temperature section, with 316L stainless from the ESP outlet onwards.

5.3 Anode furnace and casting wheel

The blister copper from the PS converter is refined in an anode furnace (typically a rotary anode furnace, similar in concept to a Holman or Hoboken-type rotating cylinder) where the residual sulfur and oxygen are adjusted to anode-quality copper. The refined copper is cast on a rotary casting wheel into copper anodes (typically 350–400 kg each) that ship to Townsville for electrorefining.

HVAC scope on the anode furnace hood is 316L stainless for the hood extract, sized for capture of the SO2 and copper fume at the open-tap position. The casting wheel hood is 316L for the molten copper surface extract; the fume is recovered in a dedicated baghouse.

5.4 Sulfuric acid plant — Mount Isa

The Mount Isa acid plant captures the SO2 from ISASMELT plus PS converter plus anode furnace into a contact sulfuric acid plant of around 1.0–1.3 Mt/yr H2SO4 capacity — one of the largest in Australia. The product acid is partially consumed on-site (in the historical Mount Isa lead-zinc concentrator and surrounding hydrometallurgical operations) and partially railed to Townsville for the fertiliser industry. The duct material, layout and SBKJ machinery scope mirrors the Port Pirie acid plant, scaled to the larger SO2 flow.

6. Copper refinery — Glencore Townsville and the cellhouse electrorefining route

Glencore Townsville Copper Refinery at Stuart QLD (the southern outskirts of Townsville) is the downstream electrorefining endpoint of the Mount Isa anode copper. The site receives copper anodes by rail from Mount Isa, electrorefines them in a sulfuric acid electrolyte cellhouse to LME Grade A cathode (99.99+ percent Cu), and ships cathode to domestic and Asian customers from Port of Townsville. Capacity around 300,000 t/yr Cu cathode.

6.1 Anode receival and preparation

Copper anodes arrive at Townsville by rail. The anode prep building strips any surface contamination, weighs and pre-positions the anodes for cellhouse loading. HVAC scope is conventional industrial — building ventilation, weighbridge office HVAC, sample preparation laboratory extract. Material is galvanised steel for the general scope, with 304L for any acid mist contact (none typically required in anode prep itself).

6.2 Cellhouse — copper electrorefining

The Townsville cellhouse contains banks of electrorefining cells, each holding alternating copper anodes and copper starter sheets (or stainless steel permanent cathodes in the modern ISA Process technology developed at Mount Isa and licensed back to Townsville). The electrolyte is sulfuric acid at 150–200 g/L H2SO4 with copper sulfate at 35–50 g/L Cu plus addition agents (thiourea, gelatin, chloride) to control cathode morphology. DC current density 220–320 A/m². At the anode the copper dissolves into the electrolyte; at the cathode the dissolved copper plates out as pure cathode copper. Impurities (Ag, Au, Se, Te, Pb, Sb, Bi, As) report to the anode slime which is collected from the cell bottom periodically and processed in a dedicated by-product plant.

HVAC scope at the copper electrorefining cellhouse is dominated by sulfuric acid mist. Unlike the zinc electrowinning cellhouse, where the anode reaction generates oxygen and significant H2SO4 mist, the copper electrorefining cellhouse generates much lower mist because the dissolving anode reaction does not evolve oxygen. The cellhouse is still managed with general mechanical ventilation and dedicated extract at the cell hoods to capture residual mist plus any chloride-bearing reagent vapour. Material is 316L stainless for the gas-contact duct, with 304L acceptable in low-mist areas.

The Townsville cellhouse runs the ISA Process — Mount Isa-developed permanent stainless steel cathode technology that replaced the legacy starter-sheet copper cathode and significantly improved cathode quality and throughput. The technology is licensed to copper refineries globally and remains a benchmark for modern copper electrorefining.

6.3 Acid mist scrubbing

Residual sulfuric acid mist from the cellhouse is captured at the cell hood and ducted to a packed-bed scrubber or mesh-pad demister to remove acid mist before discharge to the stack. Material in the gas-contact duct from hood to demister is 316L stainless or FRP (fibreglass-reinforced plastic with vinyl ester or epoxy resin). The non-metallic FRP route is preferred in some installations for cost reasons but requires careful electrical bonding and fire-rating consideration; SBKJ scope is the 316L stainless outer protective ductwork around any FRP run, plus the 316L direct-contact duct where specified.

6.4 By-product recovery

The anode slime from the cellhouse bottom is rich in silver, gold, selenium, tellurium and other minor metals. The slime is processed in a dedicated by-product recovery building — typically through pressure leach, alkaline leach, Doré silver-gold smelting and electrolytic refining of silver and gold. The HVAC scope at by-product recovery includes acid mist scrubbing (316L), alkaline mist scrubbing (304L acceptable), and Doré furnace hood extract (refractory-lined carbon steel on the hot side, 316L on the cold side).

7. Zinc refinery — Sun Metals Townsville and Nyrstar Hobart, Electrolytic Zinc EZ process

The two operating Australian zinc smelters — Sun Metals at Stuart QLD (around 250,000 t/yr Zn, commissioned in 1999 as a greenfield project under Korea Zinc, now under Korea Zinc Group) and Nyrstar Hobart at Risdon TAS (around 280,000 t/yr Zn, in continuous operation since 1917) — both operate the Electrolytic Zinc (EZ) process. The route: zinc concentrate (sphalerite ZnS) is roasted in a fluid bed roaster to zinc oxide (ZnO) calcine while liberating SO2 to the acid plant; the calcine is leached in dilute sulfuric acid (from the cellhouse spent electrolyte) to produce a pregnant zinc sulfate solution; the solution is purified (cementation with zinc dust to drop out copper, cadmium and cobalt); and the purified solution is electrowon in a cellhouse to produce zinc cathode at 99.99+ percent Zn.

7.1 Fluid bed roaster

The zinc concentrate is roasted in a fluid bed roaster at 900–950°C with air, producing ZnO calcine and SO2 gas at 8–11 percent by volume. The fluid bed roaster off-gas is at 900°C with significant cadmium, mercury and other volatile impurity carry-over. The hood and duct from roaster to waste heat boiler is heavy welded refractory-lined carbon steel; after the boiler at 350–400°C the duct transitions to 309S/310S then to 316L stainless from the ESP outlet through the acid plant gas train.

Cadmium control is a particular challenge at the zinc roaster. Sphalerite concentrate carries cadmium at 0.1–0.3 percent Cd (as a substitutional impurity in the sphalerite lattice — cadmium and zinc have very similar ionic radii and substitute readily). At roasting temperature the cadmium volatilises as CdO fume and carries through the gas train. The cadmium is dropped out at the ESP and at the gas cleaning train, recovered as Cd cake or Cd metal in a dedicated by-product circuit. Safe Work Australia WES for cadmium is 0.01 mg/m³ TWA — one of the most stringent limits in the schedule — and operator exposure at the by-product cadmium plant requires HEPA secondary filtration and full-face respirator PPE.

7.2 Acid plant — sulfuric acid from roaster SO2

The sulfuric acid plants at Sun Metals (around 700,000 t/yr H2SO4) and Nyrstar Hobart (around 600,000 t/yr H2SO4) capture the roaster SO2 into contact sulfuric acid. The gas train and duct material match the Port Pirie and Mount Isa pattern: refractory-lined carbon steel hot side, 309S/310S transitional, 316L stainless cold side from ESP through drying tower, converter beds, interpass absorption, final absorption to stack. The product acid is partially consumed on-site (for calcine leach) and partially sold externally — Sun Metals supplies Incitec Pivot Phosphate Hill and other fertiliser customers via Port of Townsville; Nyrstar Hobart supplies the Tasmanian and Victorian acid market.

7.3 Leach and purification

The roaster calcine is leached in spent electrolyte plus make-up sulfuric acid in a series of leach tanks at 60–80°C. The pregnant solution is then purified by cementation — adding zinc dust to displace copper, cadmium, cobalt, nickel and other impurities below zinc in the electromotive series. The purified solution is filtered, polished and pumped to the cellhouse.

HVAC scope at leach and purification is local extract at every leach tank vent, every cementation tank, every thickener overflow launder and every filter. The exhaust is acid mist plus water vapour with trace chlorine (where chloride-bearing minerals report through the leach) and trace H2S (where sulfide carry-over from the calcine is reduced in the leach). Material is 316L stainless for gas-contact duct, sloped to condensate drain.

7.4 Cellhouse — zinc electrowinning

The zinc electrowinning cellhouse is the heart of an EZ zinc smelter and the principal HVAC challenge. Cells contain lead-silver anodes (Pb with 0.5–1.0 percent Ag for corrosion resistance) and aluminium cathode blanks. DC current density 400–700 A/m² at 3.4–3.7 V per cell. At the anode oxygen evolves from water electrolysis; at the cathode zinc plates out as 99.99+ percent Zn cathode that is stripped every 24–48 hours. The oxygen evolution at the anode generates significant sulfuric acid mist with droplet size 1–10 µm and acid concentration matching the cellhouse electrolyte at 150–200 g/L H2SO4.

Cellhouse atmospheric H2SO4 mist is the principal occupational health hazard. Safe Work Australia WES for H2SO4 mist is 0.2 mg/m³ TWA (thoracic fraction), and the cellhouse extract must keep operator-zone concentration below this limit. Engineering controls are layered: surfactant addition to the electrolyte to suppress mist generation at the anode (modern hexavalent-chromium-free organic mist suppressants such as proprietary saponin-based or fluorinated surfactants — Australian smelters have moved away from the legacy chromium-bearing reagents in line with the Safe Work Australia Cr VI WES of 0.05 mg/m³); cell-level capture hood at the cell headspace with extract velocity 0.3–0.6 m/s at the hood face; FRP or 316L stainless duct from hood to demister; packed-bed scrubber or mesh-pad demister with NaOH or water scrubbing solution; roof-level discharge to stack with continuous H2SO4 mist monitoring at the boundary per state EPA EPL conditions.

SBKJ SBAL-V auto duct line in 316L mode at 1.5 mm wall covers the 316L stainless gas-contact duct scope. The SBFB-1500 spiral duct line covers the round duct mains running from cellhouse to scrubber. The SBSF-1525 stitchwelder provides the continuous seam welding and the SBPC1500 plasma cutter handles the saddle connections. The SBLR-600 site welder handles field joins.

7.5 Melting, casting and shipping

The stripped zinc cathodes are melted in induction or fuel-fired holding furnaces and cast into ingots, jumbos or continuous-cast strip for shipping. The melting furnace hood extract handles ZnO fume from the molten zinc surface (Zn fume volatility is significant above 600°C). Material is 316L stainless for the hood and duct; the fume is recovered in a dedicated baghouse and recycled to the cellhouse leach.

8. Nickel refinery — BHP Kwinana and the Sherritt-Gordon ammoniacal leach route

BHP Kwinana Nickel Refinery at Kwinana WA is the downstream refining endpoint for the BHP Nickel West business. The site refines nickel matte (or in the transition period nickel intermediate) to nickel metal product (briquette and powder) using the Sherritt-Gordon ammoniacal leach route — a hydrometallurgical process distinct from the pyrometallurgical routes at the lead, copper and zinc smelters. Capacity around 65,000 t/yr Ni metal.

8.1 Matte receival and grinding

Nickel matte arrives at Kwinana by rail from the Kalgoorlie smelter (historically; in the smelter decommissioning transition the feedstock arrangement is changing). The matte is ground and slurried for downstream leaching. HVAC scope at matte receival is dust extract at the matte handling — nickel matte itself is non-volatile at ambient conditions but the dust carries nickel sulfide which is a Safe Work Australia listed carcinogen. WES for nickel as inorganic compounds is 0.1 mg/m³ TWA, and the matte handling extract must keep operator exposure below this limit. Material is galvanised steel with sealed duct construction and HEPA secondary filtration on the bag filter.

8.2 Ammoniacal leach

The ground matte is leached in ammoniacal solution (NH3 plus (NH4)2SO4 at elevated temperature and pressure) to dissolve nickel and cobalt into solution as ammine complexes. The leach is a multi-stage operation with autoclaves, atmospheric leach tanks and counter-current decantation washers. The atmosphere around the leach plant is dominated by ammonia vapour and water vapour, with Safe Work Australia WES for NH3 at 25 ppm TWA and 35 ppm STEL.

HVAC scope at the ammoniacal leach is local extract at every autoclave vent, every leach tank gas headspace, every CCD launder, every dilution tank. The gas-contact duct is 316L stainless (mostly to handle the alkaline ammoniacal solution and trace H2S from the matte sulfide oxidation) sized to AS 4254 medium-pressure construction. The extracted gas is taken to an ammonia recovery absorber (water scrubbing or weak acid absorption) before discharge.

The autoclave vent itself is the highest-pressure point in the system, with flash steam at 150–200°C carrying ammonia, H2S and water. Material is titanium (Grade 2 or 7) for the wetted autoclave parts and 316L stainless for the vent duct and condensate drainage. The downstream HVAC scope around the autoclave farm is significant — operator pulpit pressurisation, cable trench ventilation, hydrogen detection system (hydrogen evolved from any oxide reduction in the autoclave), and emergency relief venting per AS 1228 (Pressure equipment — General requirements).

8.3 Hydrogen reduction

The pregnant nickel ammine solution is reduced in a series of hydrogen reduction autoclaves at elevated temperature and pressure, with hydrogen gas displacing nickel metal as fine powder which is then briquetted, sintered and packaged as product. The hydrogen reduction circuit is one of the most hazardous in Australian heavy industry — hydrogen at 4 percent in air is the lower explosive limit, and the reduction autoclave headspace and downstream duct system carry hydrogen continuously.

HVAC scope at hydrogen reduction is dominated by hydrogen detection and explosion safety. The hood and ductwork from the autoclave vent through the off-gas recovery is 316L stainless, sized to AS 4254 high-pressure construction, with continuous hydrogen analysers at every junction and trip logic to inert the system with nitrogen on detection above 25 percent of LEL. AS/NZS 60079.10.1 zone classification for the hydrogen reduction area is Zone 1 (gas present in normal operation) with corresponding Ex-rated electrical equipment.

8.4 Acid plant — Kwinana

The Kwinana refinery includes a dedicated sulfuric acid plant burning sulphur (rather than smelter SO2) to produce the H2SO4 used internally for ammonium sulfate recovery and pH control. Capacity around 200,000 t/yr H2SO4. The acid plant gas train follows the standard 316L stainless construction from the sulphur burner waste heat boiler outlet through the converter beds, interpass absorption and final absorption to the stack.

8.5 Cobalt by-product

The Kwinana refinery is one of the largest cobalt by-product producers in the southern hemisphere — the cobalt is recovered from the post-nickel-precipitation barren solution using cobalt-specific solvent extraction or ion exchange. The HVAC scope at cobalt SX is the kerosene solvent diluent vapour extract (Safe Work Australia WES for kerosene hydrocarbon at 200 mg/m³ TWA) and the cobalt oxide product handling. Material is 316L stainless for the SX building extract and galvanised steel for the cobalt product packaging area.

9. Nickel laterite — First Quantum Ravensthorpe and the HPAL route

First Quantum Minerals Ravensthorpe Nickel at Ravensthorpe WA is the operating Australian nickel laterite project — restarting and ramping back up through 2025–26 after a long care-and-maintenance period. Capacity around 30,000 t/yr Ni in MHP mixed hydroxide product. The route is High-Pressure Acid Leach (HPAL): limonitic and saprolitic laterite ore is slurried and pumped into titanium-clad autoclaves at 250°C and 4–5 MPa, leaching nickel and cobalt into solution with concentrated sulfuric acid. The pregnant leach solution is neutralised, the iron precipitated as hematite, the nickel and cobalt precipitated as MHP for shipping to refineries offshore (in the FQM commercial model, MHP is sold rather than further refined on-site).

9.1 Ore preparation and slurrying

Run-of-mine laterite is crushed, washed and slurried for autoclave feed. HVAC scope is conventional industrial dust extract at the crusher, screening and slurry preparation. Material is galvanised steel with abrasion-resistant lining at elbows.

9.2 HPAL autoclave train

The autoclave is the heart of the HPAL plant — a titanium-clad pressure vessel operating at 250°C and 4–5 MPa with continuous slurry feed and discharge. The vent gas from the autoclave is flash steam plus residual H2S and SO2 at let-down pressure. HVAC scope at the autoclave farm is the vent duct (316L stainless), the autoclave hall building ventilation (galvanised steel with positive pressure to keep building atmosphere outside the autoclave envelope), and the operator pulpit pressurisation. The autoclave shell itself is heavy fabrication procured separately from specialist titanium-clad pressure vessel manufacturers.

9.3 Counter-current decantation and neutralisation

The autoclave discharge is washed in counter-current decantation thickeners and then neutralised with limestone or lime to precipitate the iron as hematite and the residual sulfate as gypsum. HVAC scope is hood extract at every thickener overflow launder and every neutralisation tank. The atmosphere is acidic with trace H2S; material is 316L stainless for gas-contact duct, sloped to condensate drainage.

9.4 MHP precipitation and shipping

The neutralised pregnant solution is treated with magnesia (MgO) to precipitate the nickel and cobalt as mixed hydroxide product (MHP) — typically 30–40 percent Ni and 3–4 percent Co plus impurities — which is filtered, dried and packaged for shipping. HVAC scope is the MHP filter and dryer extract (galvanised steel with 316L wetted parts) and the packaging area dust extract.

9.5 Acid plant — Ravensthorpe

The Ravensthorpe acid plant burns sulphur to produce H2SO4 for the HPAL feed. Capacity sized to the HPAL acid demand (around 400,000 t/yr H2SO4). The gas train follows the standard 316L stainless construction.

10. Nickel smelter — BHP Kalgoorlie (decommissioning) and the flash smelter route

The BHP Kalgoorlie Nickel Smelter at Kambalda WA operated for decades as the pyrometallurgical front end of the BHP Nickel West business, smelting Mount Keith and Leinster nickel sulfide concentrate (pentlandite (FeNi)9S8 plus pyrrhotite Fe(1-x)S plus chalcopyrite CuFeS2 plus minor minerals) to nickel matte at around 75 percent Ni in matte. The route was a flash smelter (Outokumpu-licensed) followed by Peirce-Smith converter aisle and matte casting. Capacity around 100,000 t/yr Ni in matte before the smelter entered the decommissioning sequence announced in 2024 as BHP transitioned its nickel position in response to global market conditions and the cost pressure from Indonesian nickel pig iron and lower-cost imported matte oversupply.

10.1 Flash smelter

The Outokumpu flash smelter is a stationary refractory-lined furnace where dried concentrate is blown into a vertical reaction shaft through a burner along with oxygen-enriched air, igniting in the shaft to form droplets of matte and slag which fall to a settler at the bottom. The off-gas at the reaction shaft exit is at 1,200–1,300°C with SO2 at 25–40 percent by volume (one of the most concentrated SO2 streams in non-ferrous smelting) and significant nickel and copper fume carry-over.

HVAC scope at the flash smelter primary hood is heavy welded refractory-lined carbon steel, with 316L stainless cold-side scope from the ESP outlet through the acid plant. The high SO2 concentration means the acid plant operates with a particularly favourable gas-train economics — 25–40 percent SO2 gas is much easier to convert to H2SO4 than the 4–8 percent SO2 from a lean smelter.

10.2 PS converter

The matte from the flash smelter is converted in a PS converter aisle similar to the copper converter at Mount Isa, but operated for nickel chemistry — the iron sulfide is oxidised to FeO and slags off, while the nickel sulfide is concentrated to a Bessemer matte at 70–75 percent Ni. The Bessemer matte is then cast to slabs for shipment to Kwinana.

10.3 Decommissioning HVAC scope

The decommissioning of the Kalgoorlie smelter has its own HVAC scope — controlled draw-down of the furnace and converter aisle, lead-bearing and nickel-bearing dust removal under HEPA secondary filtration, demolition contractor PPE and respiratory programmes, and final building scrub-down to environmental closure standard. The legacy 316L stainless acid plant duct is being assessed for re-use in the surviving Kwinana refinery operations, salvaged for stainless scrap, or left in place pending site remediation.

11. Tin — Renison Bell concentrate handling and the Tasmanian operations

Renison Bell on the west coast of Tasmania is Australia's principal tin operation, producing cassiterite (SnO2) concentrate at around 8,500 t/yr Sn-in-concentrate. The site is operated by Bluestone Mines Tasmania Joint Venture (BMTJV), a JV between Metals X and Yunnan Tin (the operational JV partner contributing tin smelter expertise on the offshore smelting side). The concentrate is railed from Renison to the Port of Burnie or shipped from a regional port for export to offshore smelters — Australia has no domestic primary tin smelter since the closure of the Greenbushes Tin Smelter in WA in the 1990s.

11.1 Concentrator HVAC scope

The Renison Bell concentrator handles run-of-mine cassiterite ore through crushing, grinding and flotation to produce a concentrate at 60–70 percent Sn. HVAC scope is conventional concentrator: crusher dust extract (mild steel with abrasion lining for the highly abrasive cassiterite), grinding mill ventilation (galvanised steel with capture at trunnion seals), flotation cell hood extract (316L stainless for the xanthate decomposition vapour carrying H2S and CS2), thickener and filter hood extract, and dryer extract.

Cassiterite is very abrasive (Mohs hardness 6–7) and the dust mains and elbows wear measurably. The standard SBKJ specification at Renison is mild steel duct with chromium-carbide overlay or ceramic-bead lining at every 30-degree elbow and tee-junction. The flotation circuit HVAC handles the reagent vapour — xanthate (sodium ethyl xanthate, the standard cassiterite flotation collector) decomposes to carbon disulfide CS2 (WES 1 ppm TWA) and hydrogen sulfide H2S (WES 10 ppm TWA), and the cell hood extract carries both species to a scrubber before stack discharge.

11.2 Dryer extract

The concentrate is dried before shipping to reduce moisture content. The dryer is typically rotary or fluid bed at 150–250°C. Dryer exhaust carries fine cassiterite dust plus residual flotation reagent vapour plus dryer fuel combustion products. Material is mild steel with abrasion lining for the dust main and 316L for any acid mist contact. Bag filter at the dryer exhaust outlet captures the dust for product recovery.

11.3 Adjacent Tasmanian operations — Avebury Nickel

Avebury Nickel near Zeehan TAS (under various recent ownership including Mallee Resources) is a nickel sulfide deposit in development — when operational it will produce nickel sulfide concentrate with HVAC requirements similar to the historical BHP Kalgoorlie concentrator front end. Pentlandite-pyrrhotite-chalcopyrite flotation generates xanthate vapour, H2S and CS2 at the cell hoods, and the concentrate dryer extract handles the fine sulfide dust under Safe Work Australia nickel WES of 0.1 mg/m³ TWA.

12. The dedicated sulfuric acid plant — the heart of every non-ferrous smelter

Every primary non-ferrous smelter in the Australian portfolio runs a captive contact sulfuric acid plant on the back end. The acid plant is the largest single piece of HVAC ductwork on the project, and it is one of the most demanding 316L stainless duct fabrication scopes in Australian heavy industry. The combined acid plant capacity across Australian non-ferrous smelters exceeds 2.5 Mt/yr H2SO4 — making the sector one of the largest single industrial gas-train ductwork users in the country.

12.1 Contact acid plant gas train

The standard contact sulfuric acid plant gas train: smelter ESP outlet (gas at 250–350°C carrying SO2 at 4–18 percent depending on smelter) → gas cleaning train (humidifier, electrostatic precipitator with mist precipitator, mercury removal) → drying tower (98–99 percent H2SO4 spray, gas at 60–80°C) → SO2 blower → primary heat exchanger → catalyst Bed 1 (vanadium pentoxide V2O5 on alumina/silica support, gas inlet 400°C, exit 600–620°C) → primary heat exchanger gas-side return → catalyst Bed 2 → secondary heat exchanger → catalyst Bed 3 → interpass absorption tower (gas-side cooling to 80°C, absorption in 98 percent H2SO4) → tertiary heat exchanger reheat → catalyst Bed 4 → final absorption tower → ID fan → stack.

Total gas train length on a 200,000 t/yr H2SO4 plant is 12–18 km. Material is 316L stainless throughout the cold side from the ESP outlet onwards, with thickness 1.5–3.0 mm depending on size and pressure class. The hot side between catalyst beds runs at 400–620°C continuously, in 309S/310S austenitic stainless or refractory-lined carbon steel. Flanging is AS 4254 high-pressure with chemical-resistant gasket (typically PTFE-faced or full PTFE for the H2SO4 service); demisters are installed at the drying tower top and absorption tower top to keep H2SO4 mist out of the downstream duct.

12.2 SBKJ machinery for the acid plant scope

SBAL-V auto duct line in 316L mode handles the cold-side acid plant duct up to the 1.5 mm × 1,500 mm rectangular envelope. SBAL-III is a lighter-duty companion for the medium-pressure return-air and ventilation duct. SBFB-1500 spiral duct line is the workhorse for the round duct sections between drying tower and converter, around the interpass absorption tower and at the final absorption tower outlet to the stack. SBSF-1525 stitchwelder provides the continuous TIG seam welding for flanging and seam closure on the 316L. SB-ZF1500 stitchwelder covers the larger continuous seam joints on absorption tower duct. SBPC1500 plasma cutter cuts saddle connections, take-offs, access door openings and reducer cones in 316L. SBLR-600 site welder covers field joins between shop-fabricated segments. SBTF-1500/1602/2020 spiral tubeformer covers the larger round duct envelope where the SBFB-1500 capacity is exceeded.

The full SBKJ machinery package for an Australian non-ferrous acid plant project — say a new 700,000 t/yr H2SO4 plant on a brownfield smelter expansion — would be: one SBAL-V auto duct line (316L mode, with galvanised secondary capability for the building services scope), one SBAL-III medium-duty companion line, one SBFB-1500 spiral duct line, one SBTF-1602 spiral tubeformer, one SBSF-1525 stitchwelder, one SB-ZF1500 stitchwelder, one SBPC1500 plasma cutter, and one SBLR-600 site welder. The buyer's fabrication shop running this configuration with a single shift can complete a 12–18 km acid plant gas train in 14–20 months at sustained production tempo, with parallel capacity for the building services HVAC scope on the same project.

13. Operator pulpit, control room and crane cabin HVAC

The operator working environment at a non-ferrous smelter is one of the most demanding in Australian heavy industry — converter aisle ambient temperature exceeds 50°C in summer, fume and dust loading exceed every Safe Work Australia WES if uncontrolled, and noise level exceeds 95 dB(A) in the converter blow and matte tap zones. Operator pulpit, crane cabin and control room HVAC is mandatory engineering control, not optional comfort.

13.1 Operator pulpit pressurisation

Every converter operator pulpit, every matte tap floor pulpit, every cellhouse cell-shorting pulpit and every refining furnace pulpit is pressurised at 25–50 Pa positive pressure with 100 percent outdoor air. The make-up air train is: outdoor-air intake with G4 pre-filter, F7 secondary filter, H13 HEPA filter, and activated-carbon impregnated filter media (specifically impregnated for SO2, H2S, NH3, As and CO breakthrough — standard activated carbon alone is inadequate for non-ferrous smelter atmospheres). The supply fan is on UPS power for emergency operation during smelter trip events when fugitive emission can spike.

Material in the make-up air duct is 316L stainless for the outdoor-air intake (because in extreme conditions the intake itself can draw in fugitive smelter atmosphere) and galvanised steel for the conditioned-air supply downstream of the AHU. SBAL-V in mixed-material mode is the standard SBKJ machinery for this scope.

13.2 Crane cabin HVAC

Every crane operator cabin (slag pot crane, matte transfer crane, anode crane, charge crane) is air-conditioned with the same HEPA + impregnated carbon filter train as the pulpit. The cabin is connected to the AHU by flexible 304L stainless duct (250 mm typical diameter) with quick-disconnect couplings for crane maintenance.

13.3 Control room HVAC

Central control rooms (smelter central, acid plant central, cellhouse central) are conditioned with N+1 redundant chilled-water or DX cooling rated for the worst-case Australian summer ambient (45°C at Port Pirie, 42°C at Mount Isa, 38°C at Townsville, 35°C at Hobart, 42°C at Kwinana). Construction is low-leakage AS 4254 medium-pressure with smoke detection on supply, gas-tight dampers, and AS/NZS 60079 Ex-rated equipment in any cable entry passing through a hazardous-area zone.

13.4 Heat stress mitigation

Outside the pulpit and cabin envelope the operators still need to work in the converter aisle, on the matte tap floor and at the cellhouse cell shorting station. Safe Work Australia heat-stress guidance drives refrigerated supply-air spot-cooling at every operator rest area, and the spot-cooling units are typically standalone packaged refrigeration units with flexible duct delivery. The duct is 316L stainless for the gas-contact section where ambient contamination is high, and galvanised steel for the conditioned-air delivery.

14. Rectifier substation and cellhouse DC power supply HVAC

The cellhouse DC power supply at every Australian non-ferrous refinery — Townsville copper, Sun Metals zinc, Nyrstar Hobart zinc, BHP Kwinana nickel — is the largest single industrial DC load on the relevant state grid after the aluminium smelters. Townsville copper draws around 50,000 A at 250–350 V DC; Sun Metals draws around 50,000 A at 600 V DC across the cellhouse; Hobart draws similar; Kwinana nickel draws around 20,000 A across the EW cellhouse plus the hydrogen reduction circuit. The rectifier substation HVAC scope handles transformer cooling, switchgear-room ventilation, battery-room ventilation and DC bus heat extract.

14.1 Transformer hall ventilation

Oil-filled transformers in the 50–250 MVA range generate 200–1,000 kW of heat each at full load. Cooling is by oil-to-air radiator banks (OFAF — Oil Forced Air Forced) or oil-to-water heat exchanger (OFWF) feeding a cooling tower. The transformer hall building ventilation is sized for the radiator heat rejection plus any oil-mist release from gasket leakage. Material is galvanised steel for the supply and return air; mineral-oil-mist eliminator at the extract per NFPA 850 fire-protection guidance.

14.2 Switchgear room ventilation

The DC switchgear (rectifier transformer secondary, DC busbar, group switches) generates significant heat at full load. The switchgear room is conditioned to 25–35°C maximum with N+1 redundant cooling, and positive-pressurised at 25–50 Pa to keep dust out. SF6-insulated switchgear (where used) requires SF6 leak detection per IEC 62271-4. Material is galvanised steel for the building-services HVAC; SF6 leak detection is process-side instrumentation.

14.3 Battery room ventilation

The DC backup battery banks (typically lead-acid VRLA or flooded cells, increasingly being upgraded to lithium-ion in newer installations) require ventilation per IEEE 484 for hydrogen evolution during charge. Air change rate 4–8 ACH continuous, with hydrogen detection at the ceiling and intermittent extract to keep H2 below 25 percent of LEL. Material is galvanised steel; the hydrogen detector and trip logic is process-side instrumentation per AS/NZS 60079.10.1 Zone 1 classification.

15. Stack discharge, continuous emission monitoring and EPA compliance

Every Australian non-ferrous smelter, refinery and acid plant operates under a state EPA Environmental Protection Licence (EPL) or equivalent, with stringent stack emission limits and continuous emission monitoring requirements. The HVAC ductwork upstream of the stack must be sized so that the stack discharge meets the EPL limits under worst-case operating conditions.

15.1 Stack design under AS 1318

AS 1318 (Industrial chimneys) is the structural design basis for the stack itself. Stack height is set by the EPA dispersion modelling — typically 80–150 m for a non-ferrous smelter acid plant stack on flat terrain, with higher stacks in valley or coastal terrain to clear local boundary layer effects. Material is refractory-lined carbon steel for the structural shell with a 316L stainless liner for the gas-contact surface (the residual SO2/SO3 at the stack inlet condenses in the boundary layer and pits unlined steel within years).

15.2 Continuous emission monitoring

The CEMS (Continuous Emission Monitoring System) at every Australian non-ferrous stack monitors SO2, NOx, particulate, opacity, temperature, flow and (depending on jurisdiction) specific metal species (lead, arsenic, cadmium, mercury). The CEMS shelter is itself an HVAC scope — a conditioned cabin at the base of the stack or partway up, with positive-pressure ventilation through HEPA + impregnated carbon filter, ducted sample lines in 316L stainless from the stack interior to the CEMS analysers. Material is galvanised steel for the building services and 316L for the sample lines.

15.3 EPL limits and boundary monitoring

Typical EPL limits on a modern Australian non-ferrous smelter acid plant: SO2 600–1,200 mg/Nm³ at stack (depending on jurisdiction and EPL vintage), NOx 200–400 mg/Nm³, particulate 30–50 mg/Nm³, opacity 5–10 percent, lead 1–5 mg/Nm³, arsenic 0.1–1 mg/Nm³, cadmium 0.1–0.5 mg/Nm³, mercury 0.05–0.1 mg/Nm³. Boundary air quality monitoring per AS 3580 confirms ground-level concentration is within the National Environment Protection (Ambient Air Quality) Measure (NEPM) for PM10, PM2.5, lead, SO2 and NO2.

16. Worked example — a brownfield non-ferrous smelter HVAC project

To anchor the scope picture, consider a representative brownfield non-ferrous smelter HVAC project: an acid plant expansion plus cellhouse capacity uplift at one of the operating Australian sites — adding 250,000 t/yr H2SO4 capacity plus 50,000 t/yr Zn cathode capacity over a 30-month engineering and construction programme. Total HVAC ductwork scope for this expansion: around 22 km of mixed material.

• Acid plant gas train (incremental) — drying tower, converter beds, interpass absorption, final absorption tower duct from ESP outlet to stack. 316L stainless throughout, 1.5–3.0 mm wall, 8 km total length at sizes 800–2,400 mm. SBAL-V (316L mode), SBFB-1500 and SBSF-1525 scope; sizes above 1,500 mm rectangular and 2,400 mm round are heavy welded fabrication.
• Cellhouse extract main — cell hood capture to mist demister to packed-bed scrubber to stack. 316L stainless, 1.5 mm wall, 4 km total length at sizes 600–1,500 mm. SBAL-V (316L mode) and SBFB-1500 scope.
• Cellhouse make-up air — building positive-pressure ventilation, conditioned-air supply, dilution air. Galvanised steel rectangular and round, 1.0 mm wall, 3 km. SBAL-V and SBTF-1602 scope.
• Operator pulpit HVAC supply and return — 8 pulpits across the acid plant and cellhouse, each with 3,000 m³/h supply at 100 percent outdoor air. Total 24,000 m³/h supply. Galvanised steel rectangular and round with 316L outdoor-air intake leg, 1.0 mm wall, 2.5 km total length. SBAL-V and SBTF scope.
• Control room HVAC — central acid plant control room plus cellhouse sub-station, total 15,000 m³/h supply. Galvanised steel rectangular, 1.0 mm wall, 1.0 km length. SBAL-V scope.
• Rectifier substation HVAC — new rectifier hall, 35,000 m³/h supply for transformer hall heat extract. Galvanised steel rectangular and round, 1.0 mm wall, 1.5 km length. SBAL-V and SBTF scope.
• Cast house and anode plant HVAC (incremental) — additional anode bake furnace flue cold side and casting wheel hood extract. Mix of galvanised, 304L and 316L, 1.5 km total. SBAL-V scope.
• Amenity and admin (incremental) — new cellhouse linesmen change rooms, shower blocks, control room mess. Galvanised steel, 0.8 mm wall, 0.5 km. SBAL-V scope.

Total SBKJ scope: around 22 km of mixed material rectangular and round HVAC duct. Total non-SBKJ scope (heavy welded refractory-lined hot-side duct, ESP and baghouse housings procured packaged, FRP inner cellhouse mist duct where specified): around 8 km. The SBKJ machinery package for this project would be: one SBAL-V auto duct line (316L mode, with galvanised secondary capability), one SBAL-III medium-duty line for the building services, one SBFB-1500 spiral duct line, one SBTF-1602 spiral tubeformer, one SBSF-1525 stitchwelder, one SB-ZF1500 stitchwelder, one SBPC1500 plasma cutter, and one SBLR-600 site welder. The buyer's fabrication shop running this configuration with a single shift can complete the 22 km scope in 18–24 months — production rate around 1.0–1.4 km per month at a sustained tempo.

17. Adjacent Australian non-ferrous, by-product and integrated industries

Beyond the primary non-ferrous value chain itself, the downstream and adjacent industries that frequently overlap with the smelter project HVAC scope:

• Aluminium — the four Australian aluminium smelters (Tomago, Boyne Island, Bell Bay, Portland) and six alumina refineries are addressed in our companion Aluminium Smelter, Alumina Refinery, Bauxite and Carbon Anode HVAC Duct Guide. Many of the EPC contractors and fabricators that serve the non-ferrous sector also serve aluminium, and the 316L stainless duct fabrication discipline transfers directly.
• Iron and steel — BlueScope Steel, Liberty Whyalla and the integrated iron-ore value chain are covered in our Steel Mill and Smelter HVAC Duct Guide and our Iron Ore Mine, Concentrator, Pellet Plant, Rail and Shiploader HVAC Duct Guide. The blast furnace primary off-gas, BOF Hood and direct-reduced iron flue chemistry is distinct from non-ferrous SO2 chemistry but the duct fabrication discipline is similar.
• Power supply — every non-ferrous smelter has dedicated power supply arrangements drawing from the relevant state grid. The on-site rectifier substation HVAC is in this guide; the supply-side gas-fired or coal-fired generation is in our Coal and Gas Power Plant HVAC Duct Guide.
• Cement and lime supply — non-ferrous smelters are major lime and limestone consumers (for slag flux and for HPAL neutralisation). Refer the Cement Plant HVAC Duct Guide for the lime kiln HVAC treatment.
• Mining ventilation — underground and open-pit mining supplying the smelters is covered in our Mining Ventilation HVAC Duct Guide.
• Foundry and re-melt — secondary lead, secondary copper and secondary aluminium re-melt operations are covered in our Foundry Iron and Steel Casting HVAC Duct Guide.

18. Industry bodies, EPC contractors and equipment suppliers

The Australian non-ferrous smelter project ecosystem revolves around a manageable list of EPC contractors and specialist equipment suppliers:

• EPC and engineering — Worley ASX:WOR (Brisbane-headquartered, the largest single EPC for Australian non-ferrous smelters and refineries), Bechtel Australia (Perth, oil and gas plus selected non-ferrous work), Hatch Australia (Brisbane, mining and metals specialist with deep TSL/ISASMELT history), Fluor Australia, KBR Australia, GR Engineering Services, Lycopodium Minerals, Mincore.
• Smelter operators — Nyrstar (Trafigura, Port Pirie and Hobart), Glencore (Mount Isa Copper, Townsville Refinery), Sun Metals (Korea Zinc Group, Townsville), BHP Nickel West (Kwinana, Kalgoorlie decommissioning), First Quantum Minerals (Ravensthorpe), Bluestone Mines Tasmania JV (Metals X, Renison Bell).
• TSL and ISASMELT licensors — Glencore Technology (ISASMELT, Mount Isa-developed and globally licensed), Outotec (Outotec TSL and Ausmelt TSL — Outotec acquired the Ausmelt technology in the early 2010s), Hatch licensed designs.
• Acid plant licensors — MECS DuPont (formerly Monsanto Enviro-Chem Systems, the leading global acid plant licensor), Outotec (formerly Lurgi licensed designs), Haldor Topsoe, FLSmidth.
• HPAL licensors — Sherritt International (Sherritt-Gordon ammoniacal leach, BHP Kwinana), Outotec (HPAL), Hatch licensed designs.
• Gas cleaning and ESP licensors — Hamon Research-Cottrell, FLSmidth Airtech, Andritz, Sumitomo Heavy Industries gas cleaning, Beltran Technologies (wet ESP for acid plant gas cleaning).
• Industry bodies — International Lead Zinc Research Organisation (ILZRO), International Copper Association (ICA), Nickel Institute, International Tin Association, Minerals Council of Australia (MCA), Australian Workers' Union (AWU), CFMMEU Mining and Energy Division.

19. SBKJ commitment to the Australian non-ferrous industry

SBKJ Group is headquartered at Box Hill North VIC with engineering, sales and after-sales support staffed locally and reachable by Australian business hours (sales@sbkjduct.com, +61 435 074 994, sbkjduct.com). Our engineering team has experience commissioning duct fabrication lines on non-ferrous smelter, refinery and acid plant projects across multiple jurisdictions, and we hold critical spares (316L flange dies, plasma consumables, welder electrodes, TDF rollers, stitchwelder copper wheels) in Victorian stock for same-week despatch to Port Pirie, Mount Isa, Townsville, Hobart, Kwinana, Kalgoorlie, Ravensthorpe and Renison Bell.

Our Australia presence is closely aligned with the major non-ferrous smelter operators and with the EPC contractors that serve them. We exhibit at ARBS 2026 in May at the Melbourne Convention and Exhibition Centre (stand 236 — operated by our Australian entity Australia Ducting Pty Ltd), and our engineers are available throughout the show and the week before and after for site visits, technical briefings and commercial discussions with smelter operators, EPC contractors and HVAC fabricators serving the Australian non-ferrous portfolio. ARBS 2026 is the premier HVAC and refrigeration trade show in the southern hemisphere, and the SBKJ stand will feature live demonstrations of the SBAL-V auto duct line in 316L mode, the SBFB-1500 spiral duct line, the SBSF-1525 stitchwelder and the SBPC1500 plasma cutter — exactly the machinery package that fabricates the 316L stainless ductwork for the acid plants, cellhouses and operator pulpit HVAC on every Australian non-ferrous smelter project.

Every non-ferrous project we quote is reviewed by our senior engineering team before pricing is released — the difference between a 304L and a 316L specification is the difference between an acid plant duct that fails in 18 months and one that lasts 15 years, and we have seen the consequences of getting that decision wrong on competitor-supplied work that we have later been called in to replace at Port Pirie, Townsville and Mount Isa. We also hold the Material Test Certificate (MTC) chain of custody for every coil of 316L stainless we process — full traceability from mill to finished duct, with PMI verification on every batch.

Contact our engineering team at sales@sbkjduct.com or call the Australian office on +61 435 074 994 for a same-day callback on any non-ferrous smelter, refinery, acid plant or cellhouse HVAC project. We respond within 12 hours during Australian business hours and provide engineer-led scoping, not salesperson dispatch. The first technical call is engineer-to-engineer.

Frequently asked questions

Why is 316L stainless steel mandatory for non-ferrous smelter SO2 acid gas and acid plant ductwork?

The roasting and smelting of sulfide ores — galena (PbS) at Nyrstar Port Pirie, sphalerite (ZnS) at Sun Metals Townsville and Nyrstar Hobart, chalcopyrite (CuFeS2) at Glencore Mount Isa, and pentlandite (FeNi)9S8 at BHP Kalgoorlie — liberates sulfur dioxide at 4–18 percent SO2 by volume in the primary off-gas. After the waste heat boiler and ESP, the gas enters a contact sulfuric acid plant where SO2 is catalytically oxidised to SO3 over vanadium pentoxide catalyst, then absorbed in 98–99 percent sulfuric acid in the absorption tower. Carbon steel pits within weeks in this environment, and even 304L develops grain-boundary attack from sulfuric acid at concentrations above 70 percent. The SBKJ recommendation across the entire acid plant gas train is 316L stainless (UNS S31603) molybdenum-stabilised austenitic, fabricated on the SBAL-V auto duct line in 316L mode at 1.5 mm wall, with continuous TIG seam welding on the SB-ZF1500 stitchwelder for the absorption tower duct and demister housings. Where service temperature exceeds 400°C continuous the specification steps to 309S/310S, and at the converter outlet above 600°C the duct is refractory-lined carbon steel.

How is arsenic As2O3 fume controlled in lead and copper smelter ductwork?

Arsenic is the dirtiest impurity in Australian lead and copper concentrates. Broken Hill lead concentrate (feeding Nyrstar Port Pirie) carries 0.2–0.8 percent arsenic; Mount Isa copper concentrate carries 0.05–0.3 percent As. During roasting, smelting and converting, arsenic volatilises as arsenic trioxide (As2O3) vapour at temperatures above 460°C and condenses on cooler duct surfaces as a fine white sublimate that builds up at every horizontal run, every elbow and every bag filter inlet plenum. Safe Work Australia WES for inorganic arsenic is 0.05 mg/m³ TWA. Control engineering requires hot ductwork (kept above 250°C until the dedicated As2O3 condenser to force condensation in a controlled vessel rather than throughout the duct system), tight hood capture at every converter mouth and slag launder, fabric filter or ESP with bagging-off and packaging of the captured As2O3 dust under HEPA-filtered local exhaust, and operator pulpit pressurisation with HEPA + activated carbon filtration.

What is the HVAC scope on a typical Australian non-ferrous smelter project?

A 200,000 t/yr Australian non-ferrous smelter such as Nyrstar Port Pirie or Glencore Mount Isa Copper Smelter runs an integrated complex of concentrate handling, drying, primary smelting, converting, refining, anode casting, cellhouse electrorefining or electrowinning, and a dedicated sulfuric acid plant. Total HVAC ductwork scope is typically 60–110 km, distributed across primary smelter and converter off-gas duct (refractory-lined transitioning to 309S/310S then 316L stainless), sulfuric acid plant gas train (316L stainless throughout), concentrate handling and dryer dust extract (mild steel with abrasion lining), bag filter and ESP plenum, cellhouse acid mist scrubbing and ventilation (FRP or 316L), pulpit and control room positive-pressure HVAC, refinery cast house and anode bake furnace extract, maintenance workshop welding fume capture, and amenity blocks. SBKJ standard machinery covers the cold-side 316L acid plant duct, cellhouse 316L scope, pulpit and control room HVAC, and general building services.

How is the zinc electrolytic cellhouse ventilated and what is acid mist control?

The zinc electrolytic cellhouse at Sun Metals Townsville and Nyrstar Hobart operates the Electrolytic Zinc EZ process — zinc sulfate solution is electrowon at 400–700 A/m² in cells with lead-silver anodes and aluminium cathodes. The cellhouse atmosphere is dominated by sulfuric acid mist generated by oxygen evolution at the anode, with mist droplet size 1–10 µm and acid concentration 150–200 g/L H2SO4. Safe Work Australia WES for H2SO4 is 0.2 mg/m³ TWA. Engineering controls are: surfactant addition to suppress mist generation (modern hexavalent-chromium-free organic mist suppressants), cell-level capture hood at extract velocity 0.3–0.6 m/s, FRP or 316L stainless duct from hood to demister, packed-bed scrubber or mesh-pad demister, and roof-level discharge with continuous H2SO4 mist monitoring. SBKJ supplies the 316L stainless outer protective ductwork and the building-services ventilation; SBAL-V in 316L mode covers all the 316L cellhouse extract scope.

What does NFPA 850 require for non-ferrous smelter fire protection?

NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations) is referenced extensively for the rectifier substation, DC bus and cellhouse electrical fire-protection design on non-ferrous smelter projects. NFPA 850 requirements drive gas-tight cable-trench ducting with smoke detection and inergen or FM-200 chemical suppression, transformer hall ventilation sized to handle a worst-case oil-mist release, switchgear room positive pressurisation, and battery room ventilation per IEEE 484. The Australian fire-engineering layer (AS 1530.4, AS 1851, AS 1668.1 smoke spill) overlays NFPA 850 — the duct construction follows AS 4254 for the building-services HVAC and AS 1530.4 fire-rated for the smoke-spill mode. SBKJ SBAL-V in galvanised steel mode covers the rectifier substation, switchgear and battery room HVAC scope on every Australian non-ferrous project.

How does the carbon monoxide monitoring requirement drive smelter duct design?

Carbon monoxide is the silent killer in non-ferrous smelter operations. Sources include incomplete combustion in the smelting furnace, reducing converters, reverberatory furnaces and any fuel-fired holding furnace. Safe Work Australia WES for carbon monoxide is 30 ppm TWA and 200 ppm STEL. Control engineering is layered: hood capture at every furnace tap and converter mouth, CO-rated extract fan with explosion-vented baghouse, continuous CO monitoring at the pulpit (electrochemical CO sensors with alarm at 30 ppm and trip at 100 ppm), positive-pressure pulpit at 25–50 Pa with HEPA + impregnated carbon filter rated for CO/SO2/H2S breakthrough, and operator personal CO monitor at every shift change. The duct material on CO-laden extract is 316L stainless from converter hood through waste heat boiler to ESP inlet (with refractory lining on hot side above 600°C), and 316L throughout the acid plant gas train.

What is the Safe Work Australia Workplace Exposure Standard for lead in pot rooms and refining?

Safe Work Australia WES for inorganic lead is 0.05 mg/m³ TWA — one of the most stringent inhalation limits in the schedule. Biological monitoring limit for blood lead is 30 µg/dL for adult male workers and 10 µg/dL for women of reproductive age. Nyrstar Port Pirie operates under the Port Pirie Smelter Transformation Programme with continuous blood lead monitoring, mandatory respiratory PPE in designated lead zones, and engineering controls at every hood capture point. HVAC drives the compliance — every concentrate transfer, every sinter strand, every TSL furnace tap, every refining kettle, every anode casting wheel has local extract at 0.5–1.0 m/s capture velocity, ducted to a fabric filter baghouse with HEPA secondary filtration. Material is 316L stainless for acid-gas-bearing legs and galvanised carbon steel for ambient-dust capture. The cellhouse and refining areas have positive-pressure pulpits at 25–50 Pa with HEPA + activated carbon supply.

How is the nickel laterite acid plant and POX autoclave ventilated?

Nickel laterite operations in Australia — First Quantum Ravensthorpe and historically BHP Yabulu — operate the High-Pressure Acid Leach (HPAL) route. Limonite ore is slurried with sulfuric acid at 250°C and 4–5 MPa inside titanium-clad autoclaves. HVAC scope is dominated by the autoclave vent (continuous discharge of flash steam plus residual H2S and SO2), the acid plant supplying the H2SO4, and the SX and EW train downstream. Material on the HPAL gas-contact side is titanium for the autoclave itself; the vent duct is 316L stainless with sloping floors for condensate drainage; the acid plant gas train follows the standard 316L stainless construction; the SX building extract is 316L for the kerosene/oxime solvent vapour. BHP Kwinana Nickel Refinery operates the Sherritt-Gordon ammoniacal leach route — distinct chemistry, with NH3 ammonia gas as the principal HVAC challenge.

What HVAC standards apply to the tin smelting and refining process at Renison Bell?

Renison Bell on the west coast of Tasmania is Australia's principal tin operation, producing cassiterite (SnO2) concentrate that is shipped offshore for smelting because Australia has no domestic primary tin smelter since the closure of the Greenbushes Tin Smelter. HVAC scope at Renison Bell is dominated by cassiterite concentrate handling, flotation circuit ventilation and concentrate dryer extract — not primary smelting. The dryer extract carries fine cassiterite dust (Mohs hardness 6–7, highly abrasive) plus residual flotation reagent vapour and dryer fuel combustion products. Material is mild steel with abrasion-resistant elbow linings and 316L stainless for any flotation cell hood extract where xanthate decomposition liberates CS2 and H2S. Safe Work Australia WES for inorganic tin is 2 mg/m³ TWA.

What is the typical lead time for HVAC ductwork on an Australian non-ferrous smelter or refinery project?

Plan 16–28 weeks from purchase order to commissioning of the SBKJ duct fabrication line. The sequence is 8–12 weeks SBKJ machine manufacture (SBAL-V auto duct line in 316L mode, SBAL-III medium-duty line, SBSF-1525 stitchwelder, SB-ZF1500 stitchwelder, SBFB-1500 spiral duct, SBPC1500 plasma cutter, SBLR-600 welder, SBTF-1500/1602/2020 spiral tubeformer), 4–6 weeks ocean freight to Port Adelaide (Nyrstar Port Pirie), Port of Townsville (Sun Metals, Glencore Townsville Refinery), Port of Hobart or Burnie (Nyrstar Hobart, Renison Bell), Fremantle (BHP Kwinana, BHP Kalgoorlie, First Quantum Ravensthorpe), or Port of Mackay (Glencore Mount Isa supply chain), 2–3 weeks Australian Border Force and Department of Agriculture customs clearance and inland trucking, then 2–3 weeks installation, commissioning and operator training at the buyer's Australian workshop.

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