RECOVERY OF PRECIOUS AND RARE EARTH METALS USING CYCLODEXTRIN

This invention relates to methods for the recovery of precious metals such as gold, silver, platinum, palladium and rare earths from precious metal-bearing materials.In particular, a method of purifying precious metal from a precious metal-bearing material comprising the stepsa) forming an aqueous acidic oxidant mixture from hydrogen peroxide an acid and a source of bromide ion, said acidic oxidant mixture having a pH in the range 0 to 6;b) contacting the acidic oxidant mixture with the precious metal bearing-material to oxidise the metal and form a metal bromide salt solution containing the metal bromide MBrn and/or [MBrn+1]− where n is the valency of the oxidised metal ion Mn+; andc) controlling the metal bromide salt solution to a value in the range 3-7 by providing alkali metal ions A+ in the solution to form an alkali metal/metal bromide solution containing the salt AMBrn+1 in solution.