| 摘要 |
<p>Arsenic is eliminated from particulate ore concentrates containing iron, sulphur and arsenic by forming an aqueous sulphuric acid slurry of the particles and oxidizing the slurry with air, oxygen-enriched air or oxygen at a temperature of 250 DEG F.-650 DEG F., and under a pressure at least equal to the vapour pressure of the slurry at that temperature, the acid content of the liquid being maintained below 10 per cent. but above that corresponding to a pH of 4.5. Mutually equivalent amounts of iron and arsenic are precipitated as acid insoluble arsenate. If any arsenic remains in solution it is precipitated, preferably after pressure relieving and cooling the slurry, by addition of further iron, e.g. as iron pyrites or in recycled leach liquor or by addition of an alkaline earth metal compound such as limestone or dolomite. The liquid resulting from the treatment contains any acid soluble metals present in the original ore, e.g. copper, silver, nickel, cobalt and zinc. Specifications 728,134 and 728,135 are referred to.</p> |
