Oxide copper ores

Figure 1.26 Process route for treatment of low-grade oxidic copper ore.

In most cases, oxide copper ores contain more than one copper oxide mineral, and also contain mixtures of sulphide and oxide copper minerals. From a processing point of view, the oxide copper ores can be divided into the following five groups ... 

Oxide copper ores. In oxide ores copper is predominantly malachite with significant quantities of cobalt oxides. According to the mineral composition, these ores can be... 

The gangue constituents and their nature are sometimes determining factors in selection of a treatment process for beneficiation of oxide copper ores. Highly weathered ores usually contain a fairly large amount of slimes, which has a negative effect on the floatability of oxide copper minerals. Also, there is an appreciable difference in floatability between oxide minerals from carbonaceous and siliceous ores. 

The mechanical strength of the surface layers of many of the oxide copper minerals is weak. Therefore, flotation of oxide copper ores using sulphidization method, can improve by reducing turbulence and attrition within the flotation cell [3],... 

The sulphidization process, which was first successfully applied on a commercial scale on lead carbonate ores, is currently the most popular method used during treatment of oxide copper ores that contain malachite and carbonaceous gangue. The commonly used sulphi-dizers are Na2S 9H20 and NaHS, with xanthate or xanthate ester. 

Selection of a reagent scheme for beneficiation of oxide copper ores depends on many factors some of the more important ones being... 

This method is the most commonly used in beneficiation if oxide copper-bearing ore. The reagent schemes used to treat oxide copper ores, mixed copper sulphide oxide ores and oxide copper cobalt ores varies from one ore type to the next, mainly by type of collector and sulphidizer used. 

Xanthated fatty acid mixture is a new line of collectors, specifically designed for beneficiation of oxide copper ores that contain dolomitic and carbonaceous gangue minerals [19]. This collector was developed after extensive laboratory development testwork. The effectiveness of this collector was compared to a standard xanthate collector in a series of continuous locked cycle tests (Table 19.5). 

The flowsheet used to treat dolomitic oxide copper ores is somewhat different from that used in the beneficiation of siliceous oxide copper ores. This is due to the fact that dolomitic ore usually contains elevated amounts of slimes, in which case a split circuit flowsheet has been adopted in a number of operations. The typical flowsheet used for treatment of dolomitic ores is shown in Figure 19.8. Usually, the scavenger tailings are deslimed and the sand fraction is retreated in a scalp copper flotation stage. When the ore is deslimed before flotation, a large amount of fine copper is lost in the slime fraction. 

Cuyper, D.J. Flotation of Oxide Copper Ores Paper Presented on the GDMB General Meeting Hague Netherlands, 1976. 

The initial research work on oxide zinc flotation dates back to the 1930s at the University of Liege, Belgium [7]. This research work was based on the earned experience of flotation of oxide copper ores. Fatty acids, which are good collectors for copper carbonates, were not applicable because the gangue minerals in the zinc oxide ores were also floatable in the presence of fatty acids. 

The use of chelating solvent extractants such as the hydroxyoximes for the flotation of oxidized copper ores has been reported 8 9 unfortunately, although laboratory tests have shown that the use of chelating collectors has potential, they are not yet in widespread commercial use. 

A process using a mixture of sulfuric acid and sodium chloride to produce hydrochloric acid as the leaching reagent for oxidized copper ore has been described by Silo (Si 6). The cupric chloride is reacted with calcium carbonate powder derived from powdered sea shells to precipitate the copper as a pulp. The leaching solution is regenerated by the addition of sulfuric acid to the residual solution from the precipitation process. 

The most important copper electrowinning production method is heap leaching of oxide copper ores with recovery by solvent extraction and electrowinning (SX-EW process). The general flowsheet of an SX-EW process is shown in Fig. 18. It is a low-cost method of copper recovery. This technology has recently been applied successfully to mixed oxide and chalcocite ores, notably in Chile. Currently, there are significant development efforts underway to try to extend heap leaching to chalcopy-rite ores. 

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