Alternative processes for sulfides(cont) Sulfide concentrate of metas with f metals with igh affinity tor o (e. g. copper Oxide concentrate Roast in air to Smelting to produce form oxide metal and So2 Reduction with carbon drogen or other Impure metal reducing agent Impure metal Meta Metal of Metal of requrred purity
Alternative processes for sulfides (cont)
Alternative processes for sulfides(cont) The predominance diagram for the Cu-S-o system appears in the next slide and should be contrasted with that for ni shown earlier in the course. For Ni, which has a fairly high affinity for oxygen, the area of the predominance diagram where the metal exists is small. For copper it is quite large and it is possible to engineer the oxidation of copper sulfide to operate in the metal predominant region. We will return to copper smelting later. But first let's look at roasting
Alternative processes for sulfides (cont). The predominance diagram for the Cu-S-O system appears in the next slide and should be contrasted with that for Ni shown earlier in the course. For Ni, which has a fairly high affinity for oxygen, the area of the predominance diagram where the metal exists is small. For copper it is quite large and it is possible to engineer the oxidation of copper sulfide to operate in the metal predominant region. We will return to copper smelting later. But first let’s look at roasting
Roasting The objective is usually to remove(or diminish) the sulfur content of a concentrate by oxidation. E g for a lead concentrate 2PbS+ 302=2PbO2+ sO2 Such reactions are typically exothermic and the heat produced is usually sufficient to bring the reactants up to reaction temperature. The equipment is illustrated in the next four slides(see reader for details)
Roasting. The objective is usually to remove (or diminish) the sulfur content of a concentrate by oxidation. E.g for a lead concentrate: 2PbS + 3O2 = 2PbO2 + SO2 Such reactions are typically exothermic and the heat produced is usually sufficient to bring the reactants up to reaction temperature. The equipment is illustrated in the next four slides (see reader for details)
Roasting(cont) Although the objective of roasting is to produce oxide from sulfide, there exists the possibility of producing sulfates, as illustrated for the pb-0-s system in the next slide. good control of temperature and gas composition are required to avoid sulfate formation Which of the four reactors illustrated might be most suitable for this
Roasting (cont). Although the objective of roasting is to produce oxide from sulfide, there exists the possibility of producing sulfates, as illustrated for the Pb-O-S system in the next slide. Good control of temperature and gas composition are required to avoid sulfate formation. Which of the four reactors illustrated might be most suitable for this?
Predominance diagram, Pb-S-O 6 100oK s PbsO4 PbSo4.2Pbo PbS PbSO4→PbO PbSO4.4Pbo Pb Pbo 12 20-18-16-14-12-108_6 Log io(oxygen partial pressure, atmosheres)
Predominance diagram, Pb-S-O