Application of the HeapSim model to the heap bioleaching of the Pueblo Viejo ore deposit

The HeapSim computer model can simulate column, crib, and heap leach processes for a variety of sulfide ores. In this work, the model was used to evaluate the feasibility of heap biooxidizing the high-grade pyrite ore from the Pueblo Viejo deposit in the Dominican Republic. Simulations have revealed few but critical conditions for the success of a full-scale heap. The heap should be inoculated with mesophiles and moderate thermophiles bacteria, as well as extreme thermophilic archaea at the start-up of the biooxidation pretreatment. These microorganisms were isolated from two slurry cultures collected at site and grown in the laboratory at different temperatures. All cell types may be indigenous to the site, but inoculation of the ore and leach solution with all cell types is necessary for the transition into different temperature regimes for best sulfide oxidation performance. To ensure that all parts of the heap achieve at least 65% sulfide oxidation in the planned 400 days of treatment, the heap height should be less than 8 m if aerated at 2 m(3)/m(2)/h and irrigated at 8 L/m(2)/h. These conditions would preclude the formation of "hot spots" that could inhibit even the extreme thermophiles. By increasing the aeration rate to 4 m(3)/m(2)/h and the irrigation rate to 11 L/m(2)/h, the heap could be stacked to 8 m. Large aeration and irrigation rates would lower the temperatures at the top and bottom of the heap. Under these conditions. all parts of the heap could be expected to achieve 65% sulfide oxidation in only 250 days, as indicated by the model. (c) 2008 Elsevier B.V. All rights reserved.