EVALUATION OF PROCESS VARIABLES IN BENCH-SCALE BIOOXIDATION OF THE OLYMPIAS CONCENTRATE

A statistically designed set of eight bio-oxidation tests on the Olymp ias concentrate was conducted in bench-scale equipment to evaluate the effects of important variables on pyrite/arsenopyrite oxidation and g old extraction. The variables studied were total retention time, feed solid concentration and particle size. High degrees of arsenopyrite ox idation were observed in all tests, as the arsenopyrite oxidation was very fast and therefore not dependent on the variables within the stud ied range. Statistical analysis of the experimental data reveals that the pyrite oxidation and gold extraction are dependent mainly on the r etention time and to a lesser extent on the particle size. The feed so lid concentration had a small influence only on the gold extraction. R egressed equations of the experimental data can be used to predict pro per operating conditions.