Geobiotics, LLC

Chris Johansson

William J Kohr

Vandy Shrader

John Shield

A heap is constructed with hypogenic copper sulfide bearing ore to include exposed sulfide mineral particles at least 25 weight % of which are hypogenic copper sulfides. The concentration of the exposed sulfide mineral particles is such that the heap includes at least 10 Kg of exposed sulfide sulfur per tonne of solids in the heap. At least 50% of the total copper in the heap is in the form of hypogenic copper sulfides. A substantial portion of the heap is heated to at least 50&#xb0; C. The heap is inoculated with a thermophilic microorganism, and bioleaching is carried out so that sufficient sulfide mineral particles in the heap are biooxidized to oxidize at least 10 Kg of sulfide sulfur per tonne of solids in the heap and to cause the dissolution of at least 50% of the copper in the heap in a relatively short period of time.

High temperature heap bioleaching process

According to the process, a heap preferably having dimensions of at least 2.5 m high and 5 m wide is constructed with hypogenic copper sulfide bearing ore. The constructed heap includes exposed sulfide mineral particles at least 25 weight % of which are hypogenic copper sulfides. The concentration of the exposed sulfide mineral particles in the heap is such that the heap includes at least 10 Kg of exposed sulfide sulfur per tonne of solids in the heap. Furthermore, at least 50% of the total copper in the heap is in the form of hypogenic copper sulfides. A substantial portion of the heap is then heated to a temperature of at least 50&deg; C. The heap is inoculated with a culture including at least one strain of thermophilic microorganisms capable of bioleaching sulfide minerals at a temperature above 50&deg; C. A process leach solution that includes sulfuric acid and ferric iron is applied to the heap. Bioleaching is carried out so that sufficient sulfide mineral particles in the heap are biooxidized to oxidize at least 10 Kg of sulfide sulfur per tonne of solids in the heap and to cause the dissolution of at least 50% of the copper in the heap into the process leach solution in a period of 210 days or less from completion of the heap. A pregnant process leach solution that contains dissolved copper is collected from the heap as it drains from the heap. Copper may then be recovered from the pregnant process leach solution.

According to the process, a heap preferably having dimensions of at least 2.5 m high and 5 m wide is constructed with chalcopyrite bearing ore. The constructed heap includes exposed sulfide mineral particles at least 25 weight % of which are chalcopyrite. The concentration of the exposed sulfide mineral particles in the heap is such that the heap includes at least 10 Kg of exposed sulfide sulfur per tonne of solids in the heap. Furthermore, at least 50% of the total copper in the heap is in the form of chalcopyrite. A substantial portion of the heap is then heated to a temperature of at least 50.degree. C. The heap is inoculated, with a culture including at least one strain of thermophilic microorganisms capable of bioleaching sulfide minerals at a temperature above 50.degree. C. A process leach solution that includes sulfuric acid and ferric iron is applied to the heap. Bioleaching is carried out so that sufficient sulfide mineral particles in the heap are biooxidized to oxidize at least 10 Kg of sulfide sulfur per tonne of solids in the heap and to cause the dissolution of at least 50% of the copper in the heap into the process leach solution in a period of 210 days or less from completion of the heap. A pregnant process leach solution that contains dissolved copper 1:3 collected from the heap as it drains from the heap. Copper may then be recovered from the pregnant process leach 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 is provided. The method includes the steps of biooxidizing a heap of refractory sulfide ore particles with a bioleachate solution; collecting, from the heap, a bioleachate off solution that includes a plurality of inhibitory materials dissolved therein, the concentration of each individual inhibitory material being below its individual inhibitory concentration but the combined concentration of at least two of the inhibitory materials being sufficient to inhibit the biooxidation rate of the refractory sulfide ore particles; conditioning the bioleachate off solution to reduce the inhibitory effect caused by the combined concentration of the at least two inhibitory materials; recycling the reconditioned bioleachate solution to the to the heap; and biooxidizing the refractory sulfide ore particles in the heap with the reconditioned bioleachate solution.

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San Bruno, CA, United States of America

Chris Johansson