Solvent Extraction Separation and Recovery of Components from Scraps Containing Nickel and Cadmium

Abstract

The solvent extraction separation of Cd²⁺ and Ni²⁺ by commercially available dialkyl-phosphoric (D2EHPA), phosphonic (PC-88A) and phosphinic acids (Cyanex 272) has been investigated. In each case cadmium is extracted at lower pH values than nickel. Under comparable conditions PC-88A and Cyanex 272 have an excellent ability to separate cadmium from nickel. The optimum pH ranges are 3.5-4.5 with PC-88A and 4.8-6.0 with Cyanex 272. The feasibility of cadmium-nickel separation by Cyanex 272 extractant have been tested in pilot-plant scale. Cadmium and nickel salt solutions have been recovered from solutions originating from the leaching of the electrode materials of Ni-Cd battery scraps. The nickel and cadmium salt solutions have further been processed to metal oxidehydrates which have been found in laboratory lists as suitable for production of negative and positive electrode materials of new Ni-Cd batteries.

Keywords:

• Solvent extraction
• phosphoric and phosphinic acids
• nagative and positive electrode
• Ni-cd batteries