THE USE OF RADIOTRACERS TO LOCATE AND ELIMINATE GOLD TRAPS FROM THE GRINDING CIRCUIT AT LA-MINE-DOYON

Free gold particles occur in many base metal and precious metal mines throughout the world. Due to the high density and malleability of gold , large circulating loads of free gold particles can build up over lim e in grinding circuits. This gold is often deposited in unintended tra ps throughout the mineral processing system. These unidentified free g old deposits represent a serious security risk as well as an inaccessi ble inventory of gold. Deposits of free gold particles often remain un detected by mine management until they are accidentally discovered whi le repairing mill equipment. Nuclear tracers have been used to determi ne the free gold recovery efficiency of gravity recovery equipment, dr ills and sampling equipment (Clarkson, 1994, 1995; Walsh and Rao, 1986 Walsh and Kelly, 1992). In November, 1993, the author inspected the g rinding circuit at La Mine Doyon in Rouyn-Noranda, Quebec and made rec ommendations to recover coarse gold and to eliminate gold traps from t he circuit. In 1995, the author salted mineral processing circuits wit h radioactive gold particles. The gamma and X-ray radiation from gold' s nuclear isotope (AU(198)) were detected through steel, in pipes, and in moving equipment using scintillometers. The radiotracers proved to be a safe, rapid and accurate method of identifying gold traps and im proving security.