| 摘要 |
<p>Copper, nickel and/or cobalt are extracted from ores thereof containing also arsenic, antimony, selenium and/or tellurium by forming a slurry thereof in aqueous sulphuric acid, supplying therein 1 to 5 per cent by weight of nitric acid based on the total liquids of said slurry and maintaining said slurry in the presence of an oxygen-containing gas at the aforesaid nitric acid concentration and a temperature of 100 DEG to 150 DEG C. The copper &c. and any iron present pass into solution as sulphates whilst the arsenic &c. primarily remains in the residue as oxide. In the case of arsenic, some of the arsenic is dissolved as As2O3 which is in part precipitated when the liquor is cooled. Preferred procedures include the use of a pressure of 10 to 200 p.s.i.g. (although open vessels may be used) and the addition of a further quantity of ore to the residual liquor to eliminate nitric acid. A part of the sulphuric acid necessary for sulphate formation may be derived from the sulphur in the ore and the liquor after removal of metal values will then generally be recycled. The nitric acid may be supplied in the slurry by means of nitrogen oxide gases.</p> |
