Pyritic smelting

The practical application of the pyritic smelting principle to suitable raw ores, and to practically all copper mattes. 

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

Total 1991 world production of sulfur in all forms was 55.6 x 10 t. The largest proportion of this production (41.7%) was obtained by removal of sulfur compounds from petroleum and natural gas (see Sulfurremoval and recovery). Deep mining of elemental sulfur deposits by the Frasch hot water process accounted for 16.9% of world production mining of elemental deposits by other methods accounted for 5.0%. Sulfur was also produced by roasting iron pyrites (17.6%) and as a by-product of the smelting of nonferrous ores (14.0%). The remaining 4.8% was produced from unspecified sources. 

The principal direct raw materials used to make sulfuric acid are elemental sulfur, spent (contaminated and diluted) sulfuric acid, and hydrogen sulfide. Elemental sulfur is by far the most widely used. In the past, iron pyrites or related compounds were often used but as of the mid-1990s this type of raw material is not common except in southern Africa, China, Ka2akhstan, Spain, Russia, and Ukraine (96). A large amount of sulfuric acid is also produced as a by-product of nonferrous metal smelting, ie, roasting sulfide ores of copper, lead, molybdenum, nickel, 2inc, or others. 

Roasting pyrite, an iron ore composed of iron sulfide, results in the oxidation and decomposition of this compound to volatile sulfur dioxide and the formation of iron oxide, which can be smelted with relative ease into iron ... 

The main carrier of arsenic in rocks and in most types of mineral deposits is iron pyrite (FcS2), which may contain >2000 mg As/kg (NRCC 1978). In localized areas, soils are contaminated by arsenic oxide fallout from smelting ores (especially sulfide ores) and combustion of arsenic-rich coal (Woolson 1975). 

Cadmia, it will be remembered, is the impure zinc oxide, containing sometimes lead and copper oxides, from the furnaces in which brass was smelted. Misy was the partly oxidized iron or copper pyrites, essentially basic sulphates of iron and copper. Synopian red was haematite. This mixture, assuming the reducing action of the fuel in the furnace, or of any other reducing agent not specified in the recipe would yield an alloy of gold and zinc, with some copper and perhaps some lead. 

Sulfur is also produced from sulfide ores (pyrites) by thermal decomposition in the absence of air, by roasting/smelting under reducing conditions, or by reaction of the ore with S02. Hydrometallurgical processes have produced sulfur from metal pyrites as a by-... 

This similarity in volumes conceals enormous structural changes in the industry s sources of supply. Table 25.1 summarizes the dramatic shifts in the sources of sulfur during this period. It shows, for example, the virtual demise of Frasch and native sources of supply, and a 54 percent reduction in sulfur values derived from sulfuric acid pyrites roasting offset by huge increases in recovered sulfur (59%) plus added sulfuric acid and S02 recoveries from metallurgical smelting, (59%). 

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