|Budget Amount *help
¥2,800,000 (Direct Cost : ¥2,800,000)
Fiscal Year 1999 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1998 : ¥1,300,000 (Direct Cost : ¥1,300,000)
The leaching of steel-making dust with sulfuric acid and hydrochloric acid has been conducted, and its kinetics has been studied. High grade steel-making dust in zinc were crushed to minus 200 mesh, and treated to extract metals under several conditions, and leaching percentages of zinc, iron and lead were investigated.
The extraction degree of iron is less than 10% even when zinc is leached out about 80% by the weak leaching condition. The leaching of iron largely depends on leaching conditions such as acid concentration and leaching temperature. The extraction of lead is very small in the sulfuric acid, while lead is preferentially leached in the hydrochloric acid. This fact may be attributed to the difference of the solubility of lead in these acid. The leaching rate obeys the logarithmic function rule, which is expected to the volume reaction model.
Sulfating roasting of steel-making dust has been conducted, and caustic soda leaching of the roasted dust has been done. The dust was roasted in the mixed gas of oxygen and sulfur dioxide, and the characteristic change was investigated.
When the dust is roasted at 600℃ in the mixed gas of oxygen and sulfur dioxide, almost all zinc is leached out by caustic soda solution. For selective leaching of zinc and lead from the dust, sulfating roasting and caustic soda leaching is effective.