Using Cyanex 923 for selective extraction in a high concentration chloride medium on nickel metal hydride battery waste

The extraction properties of the solvating extractant trialkylphosphine oxide mixture Cyanex 923 have been investigated using liquid–liquid extraction methods on leach liquors from nickel metal hydride batteries dissolved in 8 M hydrochloric acid. Separation routes for leach liquors from individual electrode materials and a mixed material were developed. The batteries used in this study contained thirteen metals and the developed separation schemes separate them in up to four fractions. The main fraction in each case contains nickel, also potassium and magnesium if present in the feed. Part of the nickel raffinate is refluxed to the dissolution step in order to reduce the amount of metals to be extracted into the organic phase. A nitrate strip step separates the cobalt and manganese from the lanthanoid content, since lanthanoid nitrate complexes are extracted.

► We develop separation routes for three cases of NiMH battery waste recycling ► The solvating extractants in Cyanex 923 can separate the 13 metals into 4 groups ► The initial step separates and purifies nickel from the other high value metals ► Selective stripping of the loaded organic phase is possible ► High concentration leach liquors, approximately 4 M metal and 8 M chloride