PROCESS FOR LEACHING NOBLE METALS FROM ORES AND ORE CONCENTRATES WITH CYANIDIC SOLUTIONS WHILE ADDING HYDROGEN PEROXIDE

摘要

A B S T R A C TThe invention relates to a process for leaching goldand/or silver from ores or ore concentrates using an aqueousalkaline cyanide solution with addition of hydrogen peroxide.The industrial application of this process has hithertobeen hampered by its lack of economy, i.e. the consumptionof H2O2 and NaCN was too high. According to the invention,it has been found that the process can be made veryeconomical and that disadvantages of the conventionalleaching process can be avoided if the addition of theaqueous H2O2 solution is regulated through the concentrationof the oxygen dissolved in the leaching solution, the leachingsolution containing from 2 to 20 mg O2 and preferably from7 to 13 mg O2 per liter. 0.5 to 5% by weight H2O2 solutionsare preferably added.The process is applicable both to leaching by agitationand to heap leaching, the addition of H2O2 being regulatedthrough measurement of the O2 concentration in a measuringstream. Despite low consumptions of H2O2 and NaCN, thegold yield is even increased in some cases and the leachingtime shortened.