METHOD OF UNDERSURFACE LEACHING OF GOLD AT AURIFEROUS ALLUVIALS Russian patent published in 1998 - IPC

FIELD: gold-mining industry. SUBSTANCE: invention, in particular, relates to leaching fine gold in placers with nonuniform gold concentration distribution. Leaching is carried out in two steps: first, with potassium and/or magnesium chloride solution containing chlorine and having density exceeding that of formation water and, then, with chlorinated recycled solution. First-step salt solution is introduced into lower gravel level. Chlorinated solution is prepared either in flow-type electrolyzer or by chlorination of salt solution. Method gives rise to increased gold recovery, especially from lower gravel level and rock bed roof and also from argillaceous rock, permits treatment duration to be reduced, solution volume to be decreased, and prevents argillaceous rock swelling. EFFECT: enhanced process efficiency. 3 cl