Investigation of kinetics of zinc leaching from electric arc furnace dust by sodium hydroxide

Kinetics of zinc leaching from electric arc furnace dust from a strip mill plant in Thailand was investigated. The studied variables were stirring speeds, sodium hydroxide concentrations, reaction temperatures and percent solid. The experimental results indicate that the rate of zinc leaching from the electric arc furnace dust increases with increasing sodium hydroxide concentration. The order of reaction with respect to sodium hydroxide concentration was determined by initial rate method and found to be 0.76 at 60 degreesC. At higher temperature, the rate of zinc leaching increases. Plot of 1-(1-F)(1/3) versus reaction time giving linear relationship indicating that a chemical reaction is the rate-determining step. The apparent activation energy was measured to be 10.78 kcal mol(-1) (45.28 kJ mol(-1)). With increasing percent solid in the leaching solution, the rate of zinc leaching decreases. At high percent solid, the maximum zinc extraction obtained depends on the zinc solubility in sodium hydroxide solution, which is lower at lower concentration of sodium hydroxide. (C) 2002 Elsevier Science B.V. All rights reserved.