Experiment Study on Ammonia System Leaching Zinc from Blast Furnace Dust

For the purpose of effectively leaching zinc from blast furnace dust by means of NH₃-(NH₄)₂SO₄-H₂O ammonia system,the effects of liquid-to-solid ratio,leaching time,leaching temperature,total ammonia concentration and stirring rate on the zinc leaching rate had been experimentally investigated,and the phase of the leaching residue had been determined.Through experimental study the optimized leaching parameters had been obtained as follows: liquid-to-solid ratio of 6 m L/g,leaching time of 60 min,leaching temperature of 20℃,total ammonia concentration of 6.0 mol/L,stirring rate 200 r/min.Under the optimized leaching condition,the leaching rate of zinc is 85.6 %.Phase analysis showed that the main components of leaching residue are SiO₂,Fe₂O₃、Fe₃O₄ and CaO,which indicated highly effective selectivity of zinc from blast furnace dust and effective separation of zinc from iron,silicon and calcium.