METHOD FOR TREATING MINERAL MATERIAL HAVING ORGANIC CARBON TO FACILITATE RECOVERY OF A PRECIOUS METAL

Provided is a process for treating refractory precious metal- containing ores, particularly gold-bearing ores, to reduce the ability of organic carbon to interfere with recovery of the precious metal. The ore may also contain sulfide materials with which the gold is associated and from which the gold is difficult to separate. The ore is comminuted (104) to a size at which at least about 80 weight percent of the ore is smaller than about 40 microns in size. The comminuted ore is then slurried and subjected to pressure oxidation (108) at severe operating conditions. The treating temperature is greater than about 190 degrees C. When sulfide minerals are present, substantially all of the sulfide sulfur must first be oxidized prior to obtaining significant benefit from the treatment of the organic carbon. Greater than about 96 % of the sulfide sulfur must be oxidized. Neutralization (114) occurs after the oxidation treatment to prepare the slurry for CIP cyanidation (118) from which gold is then recovered (128).