Cobalt hydroxide, removal

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. 

Lithium nickel cobalt oxides can be prepared using routes similar to those used in the preparation of LiCoOj, although the properties of the material are more sensitive to the preparative method. Preparations of lithium nickel cobalt oxides are designed to achieve molecular mixing of the cobalt and nickel materials prior to their reaction. Lithium cobalt nickel oxides have been prepared from lithium, nickel and cobalt hydroxide co-precipitates from nitrate solutions, treated between 400°C and 800°C after removal of excess water. Another preparation includes treatment of Li2C03, C0CO3 and Ni(N03>2 6H2O at 400°C. ... 

In this method, a metal oxide or hydroxide is slurried in an organic solvent, neodecanoic acid is slowly added, and the mixture is refluxed to remove the water. Salts that are basic can be prepared by using less than stoichiometric amounts of acid. This method has been used in the preparation of metal salts of silver (80) and vanadium (81). The third method of preparation is similar to the fusion process, the difference is the use of finely divided metal as the starting material instead of the metal oxide or hydroxide. This method has been appHed to the preparation of cobalt neodecanoate (82). Salts of tin (83) and antimony (84) have been prepared by the fusion method, starting with lower carboxyHc acids, then replacing these acids with neodecanoic acid. 

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. 

The rate showed a first-order dependence on the concentrations of both hydroxide and the cobalt complex, and Hogenkamp 89) suggested that the initial step was the removal of a proton from the /3-carbon, followed by the elimination of Co(I). Schrauzer, Weber, and Beckham 159) were subsequently able to show the formation of 7r-olefin-Co(I) complexes in... 

Mixing of the electrode products causes hydrolytic precipitation of the nickel and, after separation of the nickel hydroxide, the filtrate was returned to the cells. The sequence of the electrolytic purification steps is outlined in Figure 6.28. Nickel hydroxide slurry is first added to the anolyte for the purpose of raising the pH to 3.7 (2 H+ + Ni(OH) = Ni2+ + 2 H20), and iron(II) is oxidized by introducing chlorine. This causes hydrolytic precipitation of the iron(III) and corrects the nickel ion deficiency by the low anodic current efficiency. The iron(III) hydroxide is removed by filteration. The clarified solution is then treated with nickel carbonate and further chlorine to oxidize the cobalt(II) and allow its separation as cobalt(I II) hydroxide. 

Coprecipitation is a partitioning process whereby toxic heavy metals precipitate from the aqueous phase even if the equilibrium solubility has not been exceeded. This process occurs when heavy metals are incorporated into the structure of silicon, aluminum, and iron oxides when these latter compounds precipitate out of solution. Iron hydroxide collects more toxic heavy metals (chromium, nickel, arsenic, selenium, cadmium, and thorium) during precipitation than aluminum hydroxide.38 Coprecipitation is considered to effectively remove trace amounts of lead and chromium from solution in injected wastes at New Johnsonville, Tennessee.39 Coprecipitation with carbonate minerals may be an important mechanism for dealing with cobalt, lead, zinc, and cadmium. 

Merox [Mercaptan oxidation] A process for removing mercaptans from petroleum fractions by extracting them into aqueous sodium hydroxide and then catalytically oxidizing them to disulfides using air. The catalyst is an organometallic compound, either a vanadium phthalocyanine supported on charcoal, or a sulfonated cobalt phthalocyanine. Developed by UOP in 1958 and widely licensed by 1994, more than 1,500 units had been built, worldwide. Unzelman, G. H. and Wolf, C. J., in Petroleum Processing Handbook, Bland, W. F. and Davidson, R. L., Eds., McGraw-Hill, New York, 1967, 3-128. 

The Sumitomo Metal Mining Co. in Japan uses a 40% solution of tri- -octylamine in xylene to separate cobalt and nickel in chloride media.44-163 194 The traces of zinc that are present are coextracted with the cobalt and, owing to the strong extraction of zinc, remain in the organic phase when the cobalt is stripped with water (cf. Figure 11). The zinc is then removed from a bleed stream of the organic phase by deprotonation stripping with sodium hydroxide solution ... 

Another process that has benefited from procedures such as that outlined above is the removal of cobalt from leach liquors derived from the extraction of nickel-bearing concentrates or mattes.406 Traditionally, the removal of cobalt from such acidic sulfate solutions has been based on the affinity of the trivalent metal ions (such as those of iron and cobalt) for hydroxide, which... 

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