Flotation of oxide copper 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],... 

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. 

Flotation of Oxide Copper and Copper Cobalt Ores... 

The most preferred sulphidizer used in flotation of oxide copper minerals is Na2S 9H20. Other sulphidizers used in operating plants include NaHS and (NH4)2S. Actually, the selection of a sulphidizer is based on the consumption required for flotation of oxide copper from particular ore types. For example, in some cases the consumption requirement of NaHS is much higher than for Na2S. Figure 19.5 shows the effect of different levels of sulphidizer on the recovery of malachite using xanthate collector. 

Rather than reiterating what is well known about flotation of gold, PGMs and oxide minerals, emphasis has been placed on the separation methods which are not so effective when using conventional treatment processes. These difficult separation methods are largely attributed to problems with selectivity between valuable minerals and gangue minerals, especially in the flotation of oxide ores and base metal oxides, such as copper, lead and zinc oxide ores. 

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. 

The examples in the preceding section, of the flotation of lead and copper ores by xanthates, was one in which chemical forces predominated in the adsorption of the collector. Flotation processes have been applied to a number of other minerals that are either ionic in type, such as potassium chloride, or are insoluble oxides such as quartz and iron oxide, or ink pigments [needed to be removed in waste paper processing [92]]. In the case of quartz, surfactants such as alkyl amines are used, and the situation is complicated by micelle formation (see next section), which can also occur in the adsorbed layer [93, 94]. 

Sulfide collectors ia geaeral show Htfle affinity for nonsulfide minerals, thus separation of one sulfide from another becomes the main issue. The nonsulfide collectors are in general less selective and this is accentuated by the large similarities in surface properties between the various nonsulfide minerals (42). Some examples of sulfide flotation are copper sulfides flotation from siUceous gangue sequential flotation of sulfides of copper, lead, and zinc from complex and massive sulfide ores and flotation recovery of extremely small (a few ppm) amounts of precious metals. Examples of nonsulfide flotation include separation of sylvite, KCl, from haUte, NaCl, which are two soluble minerals having similar properties selective flocculation—flotation separation of iron oxides from siUca separation of feldspar from siUca, siUcates, and oxides phosphate rock separation from siUca and carbonates and coal flotation. 

The flotation characteristics of the oxide copper minerals from natural ore are dependent on several main factors, some of which include the following ... 

Floatability of malachite is one of the most important oxide copper minerals for production of copper from oxide ores using flotation. Extensive research has been carried out by a number of researchers [4-7] in which various flotation methods were examined. 

In recent years, a new class of collectors, consisting of xanthated fatty acids (TY collector), and monoester-modified xanthate (PM230) have found industrial applications with improved metallurgical results. From plant practice, treating oxide copper and copper cobalt ores, two basic flotation methods are practiced (a) sulphidization flotation method, and (b) anionic flotation method. 

In a large number of oxide flotation plants, sodium silicate (Na2Si03) is used as a gangue depressant. In the past two decades, a new line of depressants has been developed and introduced into a number of operating plants. Some of these depressants include (a) a mixture of sodium phosphate and lignin sulphonate (i.e. depressant 3XD), (b) a mixture of a low-molecular-weight acrylic acid and sodium silicate (depressant 2D) and (c) hydrosol based on the reaction of sodium silicate with alumina sulphate (depressant SD). These depressants were extensively examined on copper oxide ores from the Nchanga mine in Zambia. 

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