Smelter acid capacity

Smelter acid capacity measures are not entirely consistent. Among several possible estimates the two following are given in thousands of short tons of 100% I SOi per annum for 1978 ... 

Obviously, not all smelter acid capacity is utilized and not all SO2 produced is transformed into acid. For copper, lead, and zinc alone, if it is assumed that only 93.5 percent of the sulfur had been removed, metal production in 1976 implied an acid production of 6 million short tons. Actual acid production was 3.2 million short tons. A doubling of acid output due to abatement... 

A 200 tonne/day contact sulfuric acid plant burning elemental sulfur costs 1.5 million to build. melter by-product sulfur dioxide is available as an alternate feed at no raw material cost, but for the same capacity requires a total investment of 3.75 million to utilize this feed. Assuming continuous operation, what would the breakeven price for sulfur have to be to make the utilization of smelter sulfur dioxide attractive if the company has to pay 10% interest on capital borrowed to build either plant Use estimates based on the first year of operation only. Assume the same labor costs. 

Table III presents the 1999 capacities and productions of the surveyed zinc smelters and refineries. The total capacity for the 20 plants was 3.2 million t/y of zinc, and the production rate was 2.8 million t/y. The average reported plant production was 141,250 t/y. The major byproducts are also given in Table III. Over 90% of the operations produced cadmium and sulfuric acid. Other important by-products include copper and gypsum.

The process for treating the baghouse dusts consists of leaching the dusts with a sulphuric acid solution, generating a lead and silver residue as a by-product, which is returned to the lead smelter, and a zinc sulphate solution, that is purified to remove Pb, Fe, Cd and As. Zinc extraction is carried out by a solvent extraction process based on Lurgi technology. The zinc-rich solution obtained in the solvent extraction plant is sent to the electrolytic zinc plant for zinc recovery and an ammonium sulphate and chloride salt is obtained fix>m the raffinate for agricultural applications. The plant has a capacity of 5,000 totmes Zn/year. 

In 1996, the total nameplate capacity for sulfuric acid in Canada was 5,681 kilotons and in the United States it was 36,306 kilotons. In 1993, the total global production of sulfuric acid was close to 135.3 megatons. Some growth is expected in the Middle East and North Africa. In Canada and the United States, sulfuric acid is transported primarily by rail and truck. Long-distance transport of sulfuric acid from smelters in remote locations makes freight costs extremely high. 

Figure 27.9 PTeconverter configuration at Olympic Dam for treating 18 volume% SO2 feed gas (after Puricelli et al., 1998). The preconverter was added to increase acid plant capacity. Gas flows between the second catalyst bed exit and the fourth catalyst bed inlet exist, but were omitted from the reference figure. A new acid plant was constructed for the new smelter at Olympic Dam in 1999. The acid plant shown above was decommissioned. Copyright 2013 MECS, Inc. All rights reserved. Used with permission of MEGS, Inc.

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