Abstract: A method is disclosed for the direct recovery of platinum group metals (PGM) from thiourea solutions or highly acidic aqueous solutions in general, such as leach solutions resulting from the acid leaching of precious metal bearing material. The method comprises reduction precipitation of the PGM from solution by alkali metal borohydride (preferably sodium or potassium borohydride) addition thereto at ambient temperature and pressure. The resulting precipitate is readily filtrable to give a product comprising high purity platinum group metal powder. The barren solution can be recycled to the upstream process.

Abstract: A process is disclosed for the direct and selective recovery of gold and/or silver from carbonate solutions, such as sodium carbonate which is used as an eluant for gold in a carbon-in-pulp process (CIP). The process comprises reduction precipitation of gold and/or silver from a carbonate solution having a pH in the alkaline range by the addition of stabilized alkali metal borohydride, such as sodium borohydride. The resulting gold and/or silver precipitate is generally of high purity and readily separated by filtration. The barren solution is in a condition such that it can be recycled to the upstream process.

Abstract: A process is disclosed for the direct recovery of gold from thiourea, thiocyanate or thiosulfate solutions or acidified thiourea leach liquor. The process comprises reduction precipitation of the gold from solution by the addition of stabilized alkali metal borohydride, preferably sodium or potassium borohydride, at ambient temperature and pressure. The resulting gold precipitate is generally of high purity and is readily separated by filtration. The barren solution is in a condition such that it can be recycled to the upstream process.