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Extractive Metallurgy of Copper 4th ed. W. Davenport et. al. (2002) Episode 3

Tham khảo tài liệu 'extractive metallurgy of copper 4th ed. w. davenport et. al. (2002) episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CHAPTER 4 Matte Smelting Fundamentals 4.1 Why Smelting Beneficiation of copper ores produces concentrates consisting mostly of sulfide minerals with small amounts of gangue oxides A12Oj CaO MgO SiO2 . Theoretically this material could be directly reacted to produce metallic Cu by oxidizing the sulfides to elemental copper and ferrous oxide CuFeS2 fo2 Cu FeO 2SO2 Cu2S 02 - 2Cu so2 FeS2 o2 - FeO 2SO2 4.1 4.2 4.3 . These reactions are exothermic meaning that they generate heat. As a result the smelting of copper concentrate should generate i molten copper and ii molten slag containing flux oxides gangue oxides and FeO. However under oxidizing conditions Cu tends to form Cu oxide as well as metal Cu2S o2 - Cu2O so2 4.4 . When this happens the Cu2O dissolves in the slag generated during coppermaking. The large amount of iron in most copper concentrates means that a large amount of slag would be generated. More slag means more lost Cu. As a result eliminating some of the iron from the concentrate before final coppermaking is a good idea. Fig. 4.1 illustrates what happens when a mixture of FeO FeS and SiO2 is heated to 1200 C. The left edge of the diagram represents a solution consisting only of FeS and FeO. In silica-free melts with FeS concentrations above 31 mass a single oxysulfide liquid is formed. However when silica is added a liquid-state 57 58 Extractive Metallurgy of Copper miscibility gap appears. This gap becomes larger as more silica is added. Lines a b c and d represent the equilibrium compositions of the two liquids. The sulfide-rich melt is known as matte. The oxide-rich melt is known as slag. Heating a sulfide concentrate to this temperature and oxidizing some of its Fe to generate a molten matte and slag i.e. CuFeS2 02 SiO2 - Cu-Fe-S FeO SiO2 so2 4 51 matte slag 1 Fig. 4.1. Simplified partial phase diagram for the Fe-O-S-SiOj system showing liquidliquid slag-matte immiscibility caused by SiOj Yazawa and Kameda 1953 . The heavy arrow shows that adding .