| 摘要 |
Gold absorbed as aurocyanide on a strongly basic anion exchange substance is recovered by extraction with an organic solvent containing a minor proportion of an inorganic acid. The strongly based anion exchange resin may be an artificial resin of the amine type, for example, "Amberlite IRA 400" (Amberlite is a R.T.M.). Solvent-acid mixtures specified are acetone-hydrochloric acid, ethyl acetate-nitric acid, ethyl alcohol-hydrochloric acid and methyl alcohol-hydrochloric acid. A small proportion of water may be present in the mixture. At least part of any copper and iron present with the gold may be removed by a preliminary elution with an aqueous solution of an alkali metal cyanide. At least part of any nickel and zinc present may be removed by a preliminary elution with a dilute aqueous mineral acid solution. The elution with aqueous alkali metal cyanide solution may follow that with aqueous mineral acid. But where copper is present in great excess of the gold a preliminary elution with 2M sodium cyanide should be carried out to remove the majority of the copper prior to any elution with dilute aqueous inorganic acid. The solution of gold obtained by the invention contains substantially all of the impurities remaining after the preliminary treatments except any cobalt and possibly some of any silver present which may be finally removed from the resin by means of an aqueous 2M potassium thiocyanate solution, leaving the resin ready for further use. The gold may be absorbed on the resin from an aqueous cyanide solution and, where the proportion of gold contained therein is small, the processes of absorption and preliminary elution may be repeated a number of times before the gold is extracted from the resin. |
