Purification of zinc ammoniacal leaching solution by cementation: Determination of optimum process conditions with experimental design by Taguchi's method

The Taguchi method was used as the experimental design to determine the optimum conditions of purification behavior of the leach solution obtained from ammoniacal ammonium carbonate leaching of nonsulphide zinc ores in Angoran region (Iran). Cementation was performed using zinc dust. The experimental conditions were studied in the range of 25–65 °C for reaction temperature (T), one to five series for zinc dust particle size distribution (S), 15–75 min for reaction time (t), 0.3–1.6 g/l for zinc dust value (M), and 300–500 rpm (R) for stirring speed. Experimental parameters and their levels were determined in the light of preliminary tests. Orthogonal array (OA) L25 (55) consisting of five parameters each with five levels, was chosen. The total optimum purification conditions obtained from this study were T2 (35 °C), S1 (series 1), t3 (45 min), M5 (1.6 g/l), and R4 (450 rpm), respectively. In these conditions, all of the impurities (cadmium, lead, nickel, and cobalt) were completely removed.