Elimination of cadmium from wet process phosphoric acid with Alamine 336

Cadmium (Cd) is a toxic heavy metal which can be found in trace quantities (< 100 ppm) in phosphate rocks, and wet process phosphoric acid (WPA). In the experimental studies described in this paper, Cd was removed from WPA by solvent extraction, using amine extractants, notably Alamine 336 as a tertiary amine extractant. In batch tests, Cd extraction from WPA under optimal conditions was calculated as 74 +/- 2.54% (95% confidence limit). It is concluded that the organic phase, containing 1% (vol) Alamine 336 + 1.5% (vol) iso-dodecanol in B-65 kerosene, has good stability and a high efficiency for Cd removal from WPA. The average Cd extraction, with 20 recyclings of organic phase to the solvent extraction circuit was calculated as 68.57%. (c) 2005 Elsevier Ltd. All rights reserved.