Copper cobalt ores

Flotation of Oxide Copper and Copper Cobalt Ores... 

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. 

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. 

The choice of reagent scheme depends largely on the type of natural ore to be treated. The three main groups of reagents used in beneficiation of oxide copper and copper cobalt ores include (a) sulphidizers, (b) collectors and (c) modifiers and depressants. 

Most operating plants that treat oxide copper and copper-cobalt ores are found in Central Africa and Southern Africa regions. A few operations exist in Chile, Brazil and Peru, where they treat mixed oxide sulphide ores or oxide copper gold ore. 

Bulatovic, S., Bigg, A.C.T., and Yen, T., Laboratory Development Testwork on Kolwezi and Komoto Oxide and Mixed Copper Cobalt Ores, Report of Investigation No. 3, 1979. 

Magmatic nickel-copper ores containing cobalt are known in the Sudbury region in Canada and in the Kambalda district in Australia. Sedimentary copper-cobalt ores constitute, from the economic point of view, the most important cobalt deposits. The ores in the Copper Belt of the Democratic Republic of Congo (DRC, formerly Zaire) and Zambia (Figure 30.3) belong to this type of deposit... 

Copper-cobalt ores from the DRC are roasted in a fluidized-bed furnace to convert sulfides to soluble oxides. After leaching with sulfuric acid, copper is removed by electrolysis. Cobalt is precipitated from the electrolyte as hydroxide. The hydroxide is redissolved, and the cobalt is obtained as metal in an electrolytic process. 

In metallurgy, hydrogen sulfide is used to precipitate copper sulfide from nickel—copper-containing ore leach solutions in Alberta, Canada, or to precipitate nickel and cobalt sulfides from sulfuric acid leaching oflaterite ores in Moa Bay, Cuba (120) (see Metallurgy, extractive metallurgy). 

Sulfide Ores ores. In the Zairian ores, cobalt sulfide as carroUite is mixed with chalcopyrite and chalcocite [21112-20-9]. For processing, the ore is finely ground and the sulfides are separated by flotation (qv) using frothers. The resulting products are leached with dilute sulfuric acid to give a copper—cobalt concentrate that is then used as a charge in an electrolytic cell to remove the copper. Because the electrolyte becomes enriched with cobalt, solution from the copper circuit is added to maintain a desirable copper concentration level. After several more steps to remove copper, iron, and aluminum, the solution is treated with milk of lime to precipitate the cobalt as the hydroxide. 

More than 200 ores are known to contain cobalt but only a few are of commercial value. The more important are arsenides and sulfides such as smaltite, C0AS2, cobaltite (or cobalt glance), CoAsS, and linnaeite, C03S4. These are invariably associated with nickel, and often also with copper and lead, and it is usually obtained as a byproduct or coproduct in the recovery of these metals. The world s major sources of cobalt are the African continent and Canada with smaller reserves in Australia and the former USSR. All the platinum metals are generally associated with each other and rhodium and iridium therefore occur wherever the other platinum metals are found. However, the relative proportions of the individual metals are by no means constant and the more important sources of rhodium are the nickel-copper-sulfide ores found in South Africa and in Sudbury, Canada, which contain about 0.1% Rh. Iridium is usually obtained from native osmiridium (Ir 50%) or iridiosmium (Ir 70%) found chiefiy in Alaska as well as South Africa. 

Sulfides such as pentlandite, (Ni,Fe)9Ss, associated with copper, cobalt and precious metals so that the ores typically contain about lt% Ni. These are found in more temperate regions such as Canada, the former Soviet Union and South Africa. 

Cobalt ores are often found in association with copper(II) sulfide. Cobalt is a silver-gray metal and is used mainly for alloying with iron. Alnico steel, an alloy of iron, nickel, cobalt, and aluminum, is used to make permanent magnets such as those in loudspeakers. Cobalt steels are hard enough to be used as surgical steels, drill bits, and lathe tools. The color of cobalt glass is due to a blue pigment that forms when cobalt(II) oxide is heated with silica and alumina. 

Mixed copper sulphide oxide ores. These contain varieties of both sulphide and oxide minerals, and are the most complex copper-bearing ores from a beneficiation point of view. The major copper minerals present in this ore type include bomite, chalcocite, covellite, malachite, cuprite and chrysocolla. In some cases, significant amounts of cobalt minerals are also present in this ore. 

Cobalt is also found in seawater, meteorites, and other ores such as linnaeite, chloanthite, and smaltite, and traces are found mixed with the ores of silver, copper, nickel, zinc, and manganese. Cobalt ores are found in Canada and parts of Africa, but most of the cobalt used in the United States is recovered as a by-product of the mining, smelting, and refining of the ores of iron, nickel, lead, copper, and zinc. 

When the sulfide ore carroUite, CuS C02S3, is the starting material, first sulfides are separated by flotation with frothers. Various flotation processes are applied. The products are then treated with dilute sulfuric acid producing a solution known as copper-cobalt concentrate. This solution is then electrolyzed to remove copper. After the removal of copper, the solution is treated with calcium hydroxide to precipitate cobalt as hydroxide. Cobalt hydroxide is filtered out and separated from other impurities. Pure cobalt hydroxide then is dissolved in sulfuric acid and the solution is again electrolyzed. Electrolysis deposits metallic cobalt on the cathode. 

Although no one had ever succeeded in extracting copper from Kupfernickel, J. H. Linck (or Link) stated in 1726 that, since it gives green solutions when dissolved in nitric acid, it must be a cobalt ore... 

He stated that the alloy was suitable for ornamental articles which would not come into contact with acid or salt and that if the copper, nickel, and cobalt ores from Riddarhytta, Hakansboda, Tunaberg, etc. 

In 1823 Johann Karl Ludwig Zincken (1790—1862) detected selenium in some ores from Zorge and Tilkerode in the eastern part of the Harz, and in 1825 Heinrich Rose analyzed them quantitatively. By heating them in a current of chlorine gas, Rose converted all the metals to chlorides and separated the selenium chloride, which was the only volatile chloride present, from the non-volatile chlorides of the metals (34). He found these minerals to be selenides of lead, copper, cobalt, and mercury. 

Space will not be devoted here to emphasis of the vast technological importance of iron and the steels nor to the discussion of ferrous metallurgy. However, typical processes for obtaining cobalt and nickel from natural sources are outlined in Table 24-1. The process for cobalt is somewhat oversimplified, for cobalt ores often contain, in addition to iron and arsenic, nickel, silver, or copper, which must also be removed. Note that nickel is conveniently purified by conversion to its volatile carbonyl, Ni(CO)4, unstable at high temperatures Mond process). 

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