INOCULUM BUILDUP

Mixed cultures of mesophilic bacteria or thermophilic microorganisms are used to effect biooxidation in a GEOLEACH ™ heap. Inoculum in the required quantity is grown up on site, starting with a small volume of culture from the laboratory. The culture is grown in a solution of nutrient salts, with periodic addition of small quantities of sulfide concentrate/ore and elemental sulfur. The suspension is agitated and aerated. As the bacterial density increases, the inoculum is transferred to progressively larger vessels and diluted by the addition of nutrient medium. This process is repeated until the required volume of inoculum is obtained.

The new GEOLEACH™ heap is inoculated by adding the inoculum to the ILS pond. Inoculum may also be added to the agglomeration drum before the ore is stacked. This method, called BIOPRO Ô , is covered by patents held by Newmont Mining Company and cross-licensed to GeoBiotics.