Sulfuric acid




Sulfuric acid is an industrial acid used in Australia to manufacture phosphate (superphosphate) fertiliser (using imported phosphate rock). It is now beginning to be used to produce ammonium phosphates fertiliser and for the extraction of nickel from laterite nickel ores.

Sulfuric acid is referenced in.... bullet Nickel projects bullet Queensland Phosphate (WMC phosphate project).

With reductions in demand for locally manufactured superphosphate fertiliser, production of sulfuric acid has fallen to one-half the level of 1980. A shutdown of sulfuric acid capacity, that was based on the use of imported elemental sulfur, was furthered by increasing acid production at non-ferrous metal smelters. The establishment of new smelter acid projects is reinforcing the trend away from using imported sulfur.

The move to smelter-sourced acid is being driven by environmental improvements promoting the clean-up and recovery of sulfur dioxide in smelter off-gases to produce sulfuric acid. The acid was produced for the merchant acid market, as a stand-alone product or for downstream operations. The most notable being the Queensland WMC plant phosphate fertiliser plant helped by the ability to increase metal production as well as the potential value of the sulfur dioxide which is driving the conversion of sulfur dioxide ahead of environmental controls.

The closure of all fertiliser phosphoric acid plants and the cutbacks in single superphosphate production capacity, has led to a near total shutdown of the sulfur-burning (old and obsolete technology) sulfuric acid operations that were integrated with the phosphate fertiliser manufacturing industry.

With sulfuric acid consumption down by 50 per cent, the significance of smelter acid output has trebled from 25 per cent in 1980 to 75 per cent in 1997. Of the ten production units, CSBP in Western Australia was the last to remain in production and now imports the acid. By year 2000, sulfuric acid capacity is anticipated to rise to 3.8 Mtpa - all from non ferrous metal production.

Major producers of smelter acid are at Kalgoorlie, Western Australia and three new east coast projects and expansions at Roxby Downs, South Australia and at Risdon, Tasmania.

Western Australia

Sulfuric acid availability in Western Australia was doubled in 1997 by the opening of Western Mining Corporation's new $A145 million plant alongside the Kalgoorlie nickel smelter 15km south of the Kalgoorlie-Boulder. The plant enables WMC to capture 99.7 per cent of the sulfur dioxide previously released. Initial capacity is 1 500 tonnes per day of acid from a nameplate capacity of 2 900 tonnes enabling production of 500 000 tonnes of acid per year. It is sold to the Cawse and Bulong nickel projects (Anaconda's Murrin Murrin nickel project produces its own sulfuric acid from 500 000 tonnes of imported sulfur. It sells some 130 000 tonnes of ammonium sulfate to CSBP at Kwinana). Other users include Nifty (25 000 tonnes per year copper), Mt Keith, Kwinana Nickel Refinery with balance exported by InterAcid. Murrin Murrin requires more acid than could be supplied by WMC.

InterAcid? Two 10 000-tonne storage tanks at the smelter, 52-tonne capacity rail tanks and 70 000 tonnes of storage at Kwinana (owned by Coogee Chemicals) provided to import acid for  Wesfarmers CSBP but most is exported given the high cost of coastal shipping under national flag vessels. A storage facility is owned by Coogee Chemicals at Port Hedland.


The Southern Copper smelter and refinery at Port Kembla, NSW, about 90km south of Sydney, was closed  in1995 but and reopened in 1999 near-doubling its associated sulfuric acid capacity. Production rose to some 250 000 tonnes until the plant closed in July 2003 under its new Japanese ownership. It is the second time the plant has closed since it began operations in 1908. The first time was in 1995 when its former owners, Southern Copper, placed the plant under care and maintenance, before its later sale to PKC. PKC's revenue had fallen steadily over the past three years as revenue streams from producing copper sank to their lowest in history from 25 US cents per pound five years ago to about 10 US cents.

The Korea Zinc smelter at Townsville, Queensland, will have a 350 000 tpa sulfuric acid plant capable of supplying merchant grade acid for Queensland Phosphate's requirements for the manufacture of phosphoric acid.

The largest new production will be at Mt Isa for the WMC phosphate project involving 1.2Mtpa of sulfuric acid.

There is also expansion of sulfuric acid capacity at Pasminco's Risdon, Tasmania zinc smelter following changed procedures that avoids the dumping of waste at sea.

Australia will therefore become a major exporter of sulfuric acid in consequence of these changes.

Manganese sulfate/manganese dioxide

Manganese sulfate

Australia imports manganese sulfate (mainly from China) which is used as a feed supplement in stock feed and fertiliser with a value from A$750 per tonne. A subsidiary of Sovereign Resources announced (April 1999) plans to manufacture 20 000 tpa of manganese sulphate from a deposit 320 km south-east of Port Hedland where there is a 1.4 million tonne deposit with an average grade of 25 per cent manganese. To cost A$12.5 million.

Manganese is currently mined by BHP at Groote Eyland in the Northern Territory producing 1.7 million tonnes [capacity 2.4 million tonnes] of which 30 per cent was used by BHP including its Bell Bay Tasmania plant producing 220,000 tonnes of ferro alloy.) It would use imported sulfur.

Manganese dioxide

Australia also manufactures electrolytic grade manganese dioxide at Newcastle NSW.

HiTec (formerly Sovereign Resources NL), which is developing a $78 mill, 20 000tonne /year electrolytic manganese dioxide plant at Port Hedland and expects this market to grow by 8 per cent/year. HiTec Resources said that it would buy the ore feed for its proposed 15 kt/year electrolytic manganese dioxide and 10 kt/year manganese sulphate plant at Port Hedland, WA; the company has a contract with Consolidated Minerals to take at least 45 kt/year of unbeneficiated fine ore (subject to tests) from its Woodie Woodie, WA mine. This material is highly regarded because it is low in phosphorus and iron, and contains moderate amounts of silica, which makes it ideal for blending.

Consolidated Minerals operates the Woodie Woodie manganese mine and the Coobina chromite mine in Western Australia. Production at Woodie Woodie was 2002/03 620,000 wet tonnes. Its Coobina mine in 2003 produced 76,000 wet tonnes.
The world market for electrolytic grade manganese dioxide is 250 000 tonnes per year largely for alkaline dry cell batteries. The market is controlled by four groups; Samancor, Eramet, CVRD and Assmag.  

Aluminium sulfate

Notes on Western Australia

The Kalgoorlie Consolidated Gold Mines (KCGM) gold ore roaster at Gidji (north of Kalgoorlie, and downwind from residential areas), is not subject to an imposed reduction (producing the equivalent of about 100 000 tonnes of sulfur, or if converted, 300 000 tonnes as sulfuric acid).

The sulfur dioxide could also have been reduced to elemental sulfur (using the Claus process). Though an additional processing cost, elemental sulfur is cheaper and safer to transport than sulfuric acid which contains two-thirds by weight of water and oxygen (from air). The additional cost of processing sulfur dioxide to sulfur, is partly offset by savings in transport and storage costs. Expressed on a tonne of sulfuric acid, transport savings using sulfur in place of the acid could save about $25 per tonne (helped by using a shipping box costing say $10 000 instead of a special container for the acid costing five times that amount). The process would be helped by the availability of North West natural gas available by the new Goldfields pipeline. However the gas, though cheaper than other energy sources in the region, has a pipeline overhead charge of around A$3.20 per gigajoule c.f. A$1.20 for gas at Kwinana (south of Perth) from the domestic line.

In Western Australia, as in the rest of Australia, the market for sulfuric acid is dominated by its use in the manufacture of superphosphate fertiliser. One part of sulfuric acid is required for two parts of rock phosphate. Wesfarmers - CSBP produces around 500 000 tpa of sulfuric acid at its Kwinana plant to produce 1 000 000 tonnes of superphosphate. About 90 per cent of sulfuric acid is used for this purpose with some 30 000 tonnes of acid is used for industrial, resource development and water treatment purposes.

It is relevant to note that the manufacture of superphosphate from imported phosphate increases the bulk substantially providing local manufacturers a substantial comparative advantage through freight cost savings at least against low analysis phosphate fertilisers. It is also important to note that West Australian soils are sulfur deficient so the superphosphate (containing sulfur) provides a supplementary element.


CSBP purchases about 80 000 tonnes per year of ammonium sulfate (representing about 50 000 tonnes of sulfuric acid) from Western Mining Corporation's nickel smelter. The ammonium sulfate is used as one of the nitrogen contributors in compound (ie. NPK) fertilisers.


CSBP as Western Australia's only superphosphate manufacturer, has been importing sulfur (complemented by supplies from the BP refinery - typically 10 000 tonnes per year) to produce the acid at four regional sites with about two-thirds at Kwinana. The Kwinana plant uses the contact process supplying a higher purity than produced by either the lead chamber process (used at their regional plants at Geraldton, Bunbury, Albany and Esperance) and acceptable for superphosphate fertiliser use). The higher quality of contact-produced acid enables CSBP to attract a price premium over other sources of acid.

In 1992-93, about 80 000 tonnes of sulfur were imported by CSBP costing about $70 per tonne (FOB, though lower prices have been recorded more recently) to produce about 270 000 tonnes of acid (production has been about 50 per cent higher during the late 1980s). Their plants (Kwinana, Bunbury, Geraldton and Albany) are operating well below maximum operating capacity.

Sulfur is also used in the Becher process to produce synthetic rutile from ilmenite. Western Australian consumption for that purpose is about 6 000 tonnes per year.

Sulfur is now imported by Murrin Murrin (Annaconda Nickel) to produce nickel from laterite deposites.

Reflecting the high cost of transport, imports of sulfuric acid have been small, typically less than 20 000 tonnes valued at less than $2m often through regional ports where high internal freight costs from Kwinana offset the cost of international freight. There is no import tariff on sulfuric acid though with international freight costs providing a substantial margin of protection, the price of sulfuric acid is well above many parts of the world (as low as US$20 per tonne ex works).


Other than to simply transport it to the Kwinana region and exports, there are three other potential applications for regionally produced sulfuric acid: bulletApplied to the manufacture of phosphate fertiliser using Mt Weld phosphate rock reserves held by CSBP. The project could absorb much of the sulfuric acid, but the remoteness, low phosphorus content (requires beneficiation) and absence of water are claimed by CSBP to render its development uneconomic for some time. bulletUsed in the manufacture of titanium dioxide pigment using the sulfate process . bulletApplied to nickel deposits in an acid leaching process (that would require more sulfuric acid than currently produced in the region). There are other potential applications as illustrated by the small scale manufacture of manganese sulfate from manganese oxide ore using sulfur dioxide from the adjoining smelter. The Gidgi smelter too may one day find it economic or be compelled to convert its sulfur dioxide to produce a further 300 000 tonnes of sulfuric acid in the Goldfields region.

The BP refinery at Kwinana, with a current capacity to produce about 20 000 tonnes of sulfur (by a modified Claus method from sour grades of imported petroleum), is expected to increase production from the current rate of 10 000 tonnes to perhaps 70 000 tonnes per year by year 2000. That amount of sulfur would be sufficient to replace most current imports of sulfur.

The potential increase in acid and sulfur, and the impact on manufacturing activities suggests potential for a range of sulfuric acid-using activities including the production of aluminium sulfate, phosphoric acid and phosphate fertilisers and other value adding activities.

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