Patent GB-594339-A (GB)
Title: Improvements in or relating to processes of recovering precious metals
IPC: C01G7/00
Filed: 1943-05-26
Abstract: Precious metals are recovered from aqueous liquids containing the metals in the form of complex acids by contacting the liquids with a solid organic anion-removal material having a basic nitrogen group and capable of being regenerated with a solution of an alkali whereby the metals are taken up by the material, removing the liquid from contact with the material, and then separating the metals from the material.  Suitable anion-removal materials are aniline black or emeraldine, keratiniferous materials such as wool and amine-formaldehyde resins.  The precious metals include gold, iridium, osmium, palladium, platinum, rhodium and ruthenium in the form of complex anions containing chlorine, cyanogen or the like. The recovery of the precious metals from the spent material (when the latter is combustible and substantially ash-free) may be effected by combustion.  The precious metal will be found in the residual ash except in the case of osmium and ruthenium when the resulting volatile oxides may be recovered by cooling the combustion gases, or by passing the gases through an absorbent such as a solution of potassium hydroxide.  Alternatively, the spent material may be treated with a solution of an alkali such as ammonium hydroxide or sodium carbonate.  Evaporation of the treating solution leaves as residue the metal salt together with excess of treating chemical. If ammonium hydroxide is used, evaporation removes excess of ammonia and further heating breaks down the residual salt, leaving pure metal. Treatment with alkali solutions does not completely remove the precious metals from the anion-removal material and after a number of cycles, the non-removable precious metals may be recovered by combustion of the material.  Examples relate to the treatment of solutions of H2 PtCl6, H2 Pd Cl6, or HAu Cl4 with emeraldine, or an aliphatic polyamine-formaldehyde resin.ALSO:Precious metals are recovered from aqueous liquids containing the metals in the form of complex acids by contacting the liquids with a solid organic anion-removal material having a basic nitrogen group and capable of being regenerated with a solution of an alkali, whereby the metals are taken up by the material, removing the liquid from contact with the material, and then separating the metals from the material. Suitable anion-removal materials are aniline black or emeraldine, paratiniferous materials such as wool and amine-formaldehyde resins. The precious metals include gold, iridium, osmium, palladium, platinum, rhodium and ruthenium in the form of complex anions containg chlorine, cyanogen or the like.  The recovery of the precious metals from the spent material (when the latter is combustible and substantially ash-free) may be effected by combustion.  The precious metal will be found in the residual ash except in the case of osmium and ruthenium when the resulting volatile oxides may be recovered by cooling the combustion gases, or by passing the gases through an absorbent such as a solution of potassium hydroxide.  Alternatively, the spent material may be treated with a solution of an alkali such as ammonium hydroxide or sodium carbonate.  Evaporation of the treating solution leaves as residue the metal salt together with excess of treating chemical. If ammonium hydroxide is used, evaporation removes excess of ammonia and further heating breaks down the residual salt leaving pure metal. Treatment with alkali solution does not completely remove the precious metals from the anion-removal material and after a number of cycles, the non-removable precious metals may be recovered by combustion of the material.  Examples relate to the treatment of solutions of H2 PtCl6, H2 Pd Cl6, or HAu Cl4 with emeraldine, or an aliphatic polyamine-formaldehyde resin.