反应详情

A commercial cobalt refining process based on the soluble cobaltic pentammine process for separating nickel from cobalt, was operated in conjunction with the above nickel refining process. This process was based on U.S. Pat. Nos. 2,694,005; 2,694,006; 2,767,054 and 2,767,055 to Schaufelburger. In the refining process mixed nickel-cobalt sulphides with a typical Ni:Co ratio of 1:1 were first leached at elevated air pressure and temperature in dilute sulphuric acid solution to dissolve the nickel and cobalt and oxidize the sulphide to sulphate. The acidic leach solution, containing cobalt and nickel sulphates, was purified to remove iron and trace metals such as Cu, Cd and Zn. Ammonia was then added to neutralize the free acid and to adjust the ammonia to metals mole ratio to form the pentammine ions of divalent nickel and cobalt. The solution was then treated with air under pressure in an autoclave, to oxidize the cobalt (II) pentammine ion to the cobalt (III) pentammine ion. The nickel (II) pentammine ion is not oxidized under these conditions. The oxidized solution was then treated in a two stage process with concentrated sulphuric acid to selectively precipitate nickel as the nickel ammonium sulphate double salt (NiSO4(NH4)SO4), leaving cobalt (III) pentammine sulphate in solution. After the second stage of nickel removal, the cobaltic solution was essentially nickel-free, with a Co-Ni ratio greater than 1000:1. The cobalt (III) ion was reduced to cobalt (II) and acid was added to adjust the NH3:Co mole ratio to about 2:1. This solution was treated with hydrogen at elevated temperature and pressure to produce cobalt metal powder containing less than 0.1% Ni. This two-stage nickel removal process, as described in U.S. Pat. No 2,822,264, produced cobalt powder with a Co:Ni ratio of greater than 1000:1.

1. additionThe solution was then treated with air under pressure in an autoclave