GB792994A - Improvements in or relating to method of utilizing exit gas from treating ores for engine power - Google Patents

Abstract

<PICT:0792994/III/1> In a high-pressure leach system wherein an aqueous slurry of an ore capable of exothermic oxidation under the leach conditions is subjected to a gas containing oxygen such as air at least 500 p.s.i.g. and 300 DEG F., an effluent gas under said pressure and temperature conditions and containing at least 35 per cent by volume of water vapour has entrained acid droplets and solid particles removed and is thereafter expanded in an expansion engine to compress a further quantity of said gas which is reacted with the slurry and is addition to generate power. Ores exemplified are gold arsenide sulphide, pyrites and chalcopyrites, which are treated as water slurries with air at 375-435 DEG F. The acid droplets &c. are removed by countercurrent spraying with aqueous sodium carbonate of pH 10 heated to 435 DEG F. and the resultant solution is recycled with periodic filtering and addition of make-up alkali. Other scrubbing solutions mentioned are aqueous solutions of the carbonates of potassium and lithium and the hydroxides of sodium and potassium. As illustrated an aqueous ore slurry is supplied from a mixing vessel 1 to an autoclave 3 into which air is introduced through line 11. The slurry is agitated to obtain contact with the air. Effluent gases are withdrawn to scrubber 4 and pass, usually at 400-500 DEG F., to an indirect heater 7 where the temperature is raised to 750-900 DEG F. They then pass to a steam turbine 8 which drives a compressor 9 supplying fresh air to the leaching process, and generator 21.