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NIRE Annual Report
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 1999

Chlorination and Selective Oxidation of Chalcopyrite Concentrate by Low-Temperature Fluidized Roasting

Rare Metals Division
Materials Processing Department
Objectives
On chalcopyrite concentrates, which make up most of the world copper resources, it is proposed to develop a continuous process of producing electrolytic copper by combining low temperature chlorination - selective oxidation pretreatment and SX-EW method. This process makes it possible to recover copper as high purity electrolytic copper, iron in the form of ferric oxide and sulfur as high purity elemental sulfur. The purpose of this study is to develop a low temperature chlorination - selective oxidation fluidized roasting method for high Cu-sulfide ores such as chalcopyrite.
Results
A three-stage fluidized bed process of chlorination, selective oxidation and sulfur chloride conversion was planned for processing of a chalcopyrite concentrate. It was found that chalcopyrite took up Cl2 effectively from 100~150°C and S% of chlorinated products was reduced to 2~3% at 270°C. With chlorination at higher temperature, however, the fluidized bed fritted owing to low temperature eutectics of FeCl3 and CuCl (m.p. 306 and 263°C) and large heat of reaction. Fe-chlorides are oxidized selectively with oxidation roasting. At higher temperature the dust loss of Cu-chloride was a serious problem. No dust loss of Cu-chloride was at 340~360°C, but it was observed often that the grains of fluidized bed grew up and discontinued fluidizing. This problem was worked out a solution by reducing S content of chlorinated products to 1.6 ~2% with thermal cure and separating the chlorination stage and selective oxidation stage such as Fig. 1. Further, it was found that the most of Cu of selective oxidized product was dissolved with dilute HCl solution and the copper concentrations of leach solutions exceeding 100g/l could be attained with the Fe/Cu ratio of 0.03.
Fig.1. Low-temperature chlorination - selective oxidation ･dechlorination process flow chart
Fig.1. Low-temperature chlorination - selective oxidation ･dechlorination process flow chart
Selected Publications
1) 2) 3) Extractive Metallurgy of Copper from Chalcopyrite Concentrates Without Sulfuric Acid Generation via Chlorination. I, II, III (Submitted to Minerals and Metallurgical Processing).
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