Method for improving the heap biooxidation rate of refractory sulfide ore particles that are biooxidized using recycled bioleachate solution

A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution, the process comprising:

• a. biooxidizing a heap comprised of refractory sulfide ore particles with a bioleachate solution and thereby producing a bioleachate off solution that includes a plurality of inhibitory materials dissolved therein;
• b. collecting the bioleachate off solution from the heap;
• c. raising the pH of the bioleachate off solution to a pH greater than 5.0 and thereby forming a precipitate;
• d. removing the precipitate from the bioleachate off solution;
• e. adjusting the pH of the bioleachate off solution to a pH suitable for biooxidation following the removal of the precipitate;
• f. recycling the bioleachate off solution to the heap;
• and
• g. biooxidizing the refractory sulfide ore particles in the heap with the recycled bioleachate off solution.

A method for at least partially biooxidizing a heap comprised of refractory sulfide ore particles using a bioleachate off solution that includes a plurality of inhibitory materials dissolved therein, wherein the concentration of each individual inhibitory material in the bioleachate off solution is below its individual inhibitory concentration, yet the combined concentration of at least two of the inhibitory materials is sufficient to inhibit the biooxidation rate of the refractory sulfide ore particles in the ore, the process comprising:

• a. conditioning the bioleachate off solution to reduce the inhibitory effect caused by the combined concentration of the at least two inhibitory materials;
• b. recycling the bioleachate off solution to the heap;
• and
• c. biooxidizing the refractory sulfide ore particles in the heap with the bioleachate off solution.

A method for at least partially biooxidizing a heap comprised of refractory sulfide ore particles using a bioleachate off solution that includes a plurality of inhibitory materials dissolved therein, the process comprising:

• a. raising the pH of the bioleachate off solution to a pH greater than 5.0 and thereby forming a precipitate;
• b. removing the precipitate from the bioleachate off solution;
• c. adjusting the pH of the bioleachate off solution to a pH suitable for biooxidation following the removal of the precipitate;
• d. recycling the bioleachate off solution to the heap;
• and
• e. biooxidizing the refractory sulfide ore particles in the heap with the bioleachate off solution.