Method for recovering copper and cobalt in sulfuric-acid slag through gas-based low-temperature reduction roasting-leaching

The invention relates to a method for recovering copper and cobalt in sulfuric-acid slag through gas-based low-temperature reduction roasting-leaching, which specifically comprises the following steps: (1) taking a proper amount of copper-cobalt-containing sulfuric-acid slag, placing the copper-cobalt-containing sulfuric-acid slag in a tubular atmosphere furnace, then introducing a CO/N2 mixed gas to completely replace air in the tubular atmosphere furnace, heating to 500-600 DEG C at a rate of 10-20 DEG C/min, carrying out heat-preservation roasting for 30-120 minutes, and carrying out gas-based low-temperature reduction roasting-leaching on the copper-cobalt-containing sulfuric-acid slag to obtain copper-cobalt-containing sulfuric-acid slag; then cooling to 60-80 DEG C to obtain roasting slag; (2) the roasted slag cooled to 60-80 DEG C is added into a sulfuric acid solution with the mass fraction of 5-30%, the liquid-solid ratio is (4-5): 1, and leaching is conducted for 20-300 min under stirring; (3) the l