Intensified alkaline leaching pretreatment of refractory gold concentrates at common temperature and pressure

摘要

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 pulveri-zing-leaching tower mill, the concentrate is ground to <35.6 μm of 95.5% while simultaneously leached by NaOH of 12kg/t, then carried out intensified alkaline leaching for 48 h 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 10~5 Pa. 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 ar-senate and sulfur to sulfate. The gold leaching rate by NaCN in 24 h 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 422 Yuan/t.