The effect of zinc dust particle size distribution on optimizing of impurities cementation in zinc ammoniacal leaching solutions by Taguchi method

摘要

The Taguchi method was used as the experimental design to determine the optimum conditions of purification behavior of leach solution obtained from ammoniacal ammonium carbonate leaching of none - sulphide 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. The orthogonal array (OA) L25 (55), five parameters each with five levels, was chosen and each experiment was repeated twice under the same conditions at different times in order to observe the effects of noise sources in the purification process. Five particle size distributions were selected by innovative method for determination of particle size distribution effect on the purification process. One hundred milliliters of leach liquor was put into the beaker. When the desired temperature of the beaker content was reached, a predetermined amount of zinc dust with defined size distribution was added into the solution while the content of the beaker was being stirred at a certain speed. Results showed that, the series 1 distribution had been proper for Cd and Co, and the series 4 distributions had been optimum for Ni and Pb. Optimum purification conditions of Cd, Pb, Ni, and Co removal were found to be T2 (35°C), S1 (series 1), t3 (45 min), M5 (1.6 g/l), and R4 (450 rpm). In these conditions, all of impurities (Cd, Pb, Ni, Co) were completely removed. These results were accepted by confidence limits that were calculated in each case.