| 摘要 |
1368192 Recovering Ni and Co from ores INTERNATIONAL NICKEL CO OF CANADA Ltd 23 March 1972 [14 April 1971] 13623/72 Heading C1A Ni and Co values are recovered from ferruginous oxide ores, e.g. limonite or serpentine, by (a) reducing the ore at a temperature of 500- 825‹ C. in e.g. an atmosphere of CO/CO2, to selectively reduce more Ni and Co than Fe, (b) leaching the reduced ore by forming it into an aqueous slurry with a mineral acid, e.g. H2SO4, HCl or HNO3, aerating the slurry with a free oxygen-containing gas to dissolve Ni and Co values and to ppt. Fe as Fe(OH)3 while maintaining the pH of the solution in the slurry at a pH of 2À5 by the incremental addition of mineral acid, (c) separating the Ni and Co containing solution by, e.g. filtration or countercurrent decantation. S values may be added to the ore before or during the reduction step, either in elemental form or as pyrites (FeS2), pyrrhotite, or H2S, preferably in an amount to give 0À1-2% S content in ore. SO2 may be mixed with the free oxygen-containing gas (air, O2-enriched air or O2) in an amount of 0À25-1 mole per mole Fe in solution. The mineral acid used is preferably H2SO4 since the Ni and Co values can then be recovered from the sulphate solutions formed by treating them with H2S at elevated pressure and at a temperature of 80-130‹ C. The ratio of CO/CO2 may be in the range 0À5-2À0. The ore may either be in finely divided form, e.g. 80%- 100 mesh (Tyler series), for reduction in rotary kilns, fluidized bed reactors and multihearth furnaces, or be pelletized for reduction in rotary or rotary hearth furnaces. The ore is preferably reduced at 600-725‹ C. when the Fe content is #30% (limonite) or at 700-825‹ C. when the Fe content is <30% (HIGH SIO2 ore). The leaching step may be carried out either in batch or continuous mode, the latter in a concurrent system in which both the liquids and solids flow through a series of aerated tanks. |
