Process for the recovery of dissolved metal values

Abstract

Abstract Metal values are recovered from aqueous solutions by chemically combining the metal with a substantially water-insoluble chelating agent adsorbed on a solid particulate matrix. Specially suited materials for the matrix are granular activated chars derived from fruit pits or coconut shell, or resins having high absorptive capacity but insignificant ion-exchange activity. Suitable chelating agents include thenoyltrifluoroacetone, 8-hydroxyquinoline, diphenylthio carbazone, dioctyl phosphoric acids, e.g. di-2-ethyl hexyl pyrophosphoric acid, mixtures of mono- and di-octyl orthophosphoric acids, mono-octyl orthophosphoric acid, di-isoamyl pyrophosphoric acid, mixtures of mono- and di-isoamyl orthophosphoric acids, mixtures of mono- and di-2-ethylhexyl orthophosphoric acids, and mixtures of mono- and di-capryl orthophosphoric acids. In one example, an extractive matrix for uranium is prepared by agitating a solution of dioctyl pyrophosphoric acid in ethanol with activated char, and the char is then removed, washed with water and dried in air. In another example an emulsion of di-2-ethylhexyl pyrophosphoric acid in water was agitated with a resin (Duolite S-30), and the resin was then removed, washed, and dried. The prepared matrix is agitated with the aqueous metal-containing medium, in conventional manner such as counter-current or batch, separated, and the matrix now containing the metal is treated with a suitable solvent to remove the chelated metal, and thus regenerate the matrix. By suitable selection of different chelating agents and operating conditions, it is possible to utilize the process to separate the individual metal components of the solution. In an example, a char containing dioctyl pyrophosphoric acid was agitated with a solution containing uranium at a pH of 1.0. The matrix was removed, and the chelated uranium recovered by stripping with a sodium carbonate-bicarbonate solution. Other methods of stripping the metal values from the matrix include washing with a solution of increased hydrogenion concentrations or by washing with a solution containing a complexing agent which forms a more stable compound with the metal, or which can successfully compete for the metal against the chelated form on the matrix. In another example a char containing 8-hydroxyquinoline was agitated with a sulphuric acid solution of cupric copper and nickelous nickel at a pH of 2.3. It is found that when the char is removed, the solution has been freed of copper, and the char is practically free of nickel. The copper may be stripped from the char by washing with a hydrochloric acid solution at pH = 1.ALSO:Metal values are recovered from aqueous solutions by chemically combining the metal with a substantially water-insoluble chelating agent adsorbed on a solid particulate matrix. Specially suited materials for the matrix are granular activated chars derived from fruit pits or coconut shell, or resins having high absorptive capacity but insignificant ion-exchange activity. Suitable chelating agents include thenoyl trifluoroacetone, 8-hydroxyquinoline, Diphenyl thiocarbazone, Diodyl phosphoric acids e.g. di-2-ethyl hexyl pyrophosphoric acid, mixtures of mono and dioctyl orthophosphoric acids, Monsoctyl orthophosphoric acid, mixtures of mono- and di-2-ethyl hexyl orthophosphoric acid, and mixtures of mono- and di-capryl orthophosphoric acids. In one example, an extractive matrix for uranium is prepared by agitating a solution of di-octyl pyrophosphoric acid in ethanol with activated char, removing the char, washing it with water, and drying in air. In another example an emulsion of di-2-ethylhexyl pyrophosphoric acid in water was agitated with a resin (Duolite S-30), the resin was removed, washed and dried. The prepared matrix is agitated with the aqueous metal solution in conventional manner such a countercurrent or batch, separated, and the matrix is then regenerated and the chelated metal removed with a suitable solvent. By suitable selection of different chelating agents and operating conditions it is possible to utilise the process to separate the component metals. In an example, a char containing dioctyl pyrophosphoric acid was agitated with a solution containing uranium at a pH of 1,0. The matrix was regenerated and the uranium recovered by stripping with a sodium carbonate-bicarbonate solution. Other methods of stripping include washing with a solution of increased pH, or with a solution containing a complexing agent which forms a more stable compound with the metal or which can successfully compete for the metal with the chelated form on the matrix. In another example a char containing 8-hydroxyquinoline was agitated with a sulphuric acid solution of cupric and nickelous at a pH of 23. It was found that the solution is freed of copper and that the char is free of nickel. The copper may be stripped from the char by washing with a hydrochloric acid at a pH of 1.

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