Intensified alkaline leaching pretreatment of refractory gold concentrates at common temperature and pressure
(Laboratory of Special Preparing and Processing Technology,
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: A new process for the hydrometallurgy of refractory gold concentrates was presented. The process comprises grinding-leaching, intensified alkaline leaching (IAL), cyanidation and adsorption. In a stirring-type pulverizing-leaching tower mill, the concentrate is ground to ＜35.6μm of 95.5 % while simultaneously leached by NaOH of 12kg/t, then carried out intensified alkaline leaching for 48h by NaOH of 108kg/t in enhanced agitation tanks with the pulp concentration of 40% solids at the environmental temperature of 9.5～13.5℃ and the environmental pressure of 105Pa. The oxidation rate of As is 94.9%, and 47.6% for S. The total consumption of NaOH is only 20% of that theoretically calculated under the conditions of full oxidation at the same oxidation rates of arsenic to arsenate and sulfur to sulfate. The gold leaching rate by NaCN in 24h is increased from 9.2% before pretreatment to 94.2%. The consumption of NaCN is 7.5kg/t, which is one times less than that before pretreatment. The extraction cost of gold is about 422Yuan/t.
Key words: refractory gold concentrates; grinding-leaching; intensified alkaline leaching (IAL); pretreatment; common temperature and pressure