Matte smelting

The essential operations of an extractive metallurgy flow sheet are the decomposition of a metallic compound to yield the metal followed by the physical separation of the reduced metal from the residue. This is usually achieved by a simple reduction or by controlled oxidation of the nonmetal and simultaneous reduction of the metal. This may be accompHshed by the matte smelting and converting processes. 

Blister copper, produced from sulfide ores by matte smelting and converting, is refined to the grade known as tough pitch copper by a multistage operation known as fire refining. 

Matte smelting involves roasting the concentrate with lime and recycled converter slag at about 1300 °C to form a slag of molten oxides of iron, silicon, and other impurities, and an immiscible matte or molten sulfide layer, which contains CU2S along with some FeS. 

Copper sulfide ore (mixed with oxide and iron ore) can also be converted to metal by matte smelting with flux (e.g., lime) to produce a matte of Cu and Fe sulfides. The matte is then roasted to FeO and Cu in a stream of air. 

World nickel metal production in 2002 was 678000 tons [39]. Hydrometallurgy has typically been applied to the treatment of nickel-copper mattes, anode nickel, and reduced laterite ore. The sulfide concentrates are usually oxidized by roasting and then smelted to copper-iron-nickel sulfide matte (75-80% Cu-Ni), which is refined or used directly to make M onel metal. Cathode nickel can be produced from a variety of electrolytes, including chloride, sulfate, or a mixed chloride-sulfate. The former two are acid systems used in leaching and electrowinning. Mixed chloride-sulfate electrolytes are used for electrorefining the nickel sulfide matte from the traditional matte-smelting operations. 

An azns=0.05 to 0.1 corresponds to a 1-2 wt% zinc solubility in the matte because the activity coefficient, yzns >n the matte is about 10 as moitioned earlier. Because the Zn solubility in a Fe-S-0 matte is very low under these conditions, the matte can be considered a Fe-S-0 temaiy system whose composition is defined at a fixed temperature, oxygen potential and sulfur potential. Based on the reported relationship between the Fe-S-0 matte composition, temperature, oxygen and sulhir potentials (2), Fe-S-0 matte compositions under the described smelting conditions have been estimated see Table I. At 1350°C and a CO/CO2 ratio between 3 and 4, azns=0.05 (or less than 1% Zn solubility in matte) requires the composition of matte of 6-7% O and Fe/S 2.7-2.9 (weight basis). The proposed matte smelting composition is shown in Figure 2 (6). 

The former two are acid systems used in leaching and electrowinning. Mixed chloride-sulfate electrolytes are used for electrorefining the nickel sulfide matte from the traditional matte-smelting operations. 

Smelting to ferronickel is essentially the same as matte smelting, except that no sulfur is added. It is often applied to laterite ores. The resulting iron-nickel alloy contains 20-50% nickel [46]. 

In the above figures, Lau and La refer to content ratio of Au Ag in matte phase and slag phase. The experiments have shown distribution coefficients of Au Ag decrease repetitively with the increases of matte grade and Cu in slag in the course of matte smelting by using copper... 

Chao bo Tang. New Process Studies on Reducing-Making Matte Smelting of Lead and Antimony, Doctor Degree Thesis, Central South University, Changsha, Hunan, 2003. 

A. Rusen, A. Geveci, Y.A. Topkaya, Usage of Colemanite in Copper Matte Smelting , Proceedings of Copper 2010, Hamburg, Germany, 1115-1122. 

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