Leaching kinetics of silver from sintering dust with thiourea

Using the sintering dust containing Ag from iron and steel metallurgical process as raw material, on the basis of phase analysis, an efficient leaching process of silver with thiourea from the dust was proposed. The effects of particle size, temperature, concentration of thiourea, leaching time and stirring speed on leaching rate of silver were examined. The results showed that silver leaching rate from water washed sintering dust could reach 90% under the conditions of ratio of liquid volume to solid mass 8 mL/g, 22 g/L thiourea and stirring speed at 400 r/min for 120 min. The leaching of silver conformed well to the shrinking core model with internal diffusion control. The apparent activation energy of silver reaction was calculated as 29.7 kJ/mol and the reaction order in acidic thiourea solution was approximately 1.