Abstract:According to the features of the sintering dust with various valuable elements, a selective coordination leaching process realizing the selective separation and recovery of lead was studied. The SEM–EDS and XRD analysis results show that lead is absorbed on the surface of iron oxide compounds, aluminosilicate and carbon grain exist in sintering dust in the form of flocculent KPb₂Cl₅, and iron mainly exists in the form of Fe₂O₃ and Fe₃O₄. The effects of pH value, leaching temperature, Cl^- concentration, leaching time and liquid-to-solid (L/S) on the leaching ratio of lead were investigated. The results show that, under the optimal conditions such as the pH value of 3.0, leaching temperature of 80 ℃, Cl^- concentration of 6mol/L, liquid-solid ratio of 10:1 and leaching time of 2 h, the lead compounds such as KPb₂Cl₅ are adsorbed on the surface of iron oxide compounds, and the aluminosilicate and carbon grains react with chlorine to form soluble complexes such as (i=1-4). The leaching ratio of lead is up to 95.7%. The selective coordination leaching process is achieved. Iron, carbon, silicon and aluminum, which are useful for iron and steel smelting, are enriched in leaching residue, while lead is leached and dissolved in the leaching solution. The lead in the leaching solution is crystallized by cooling crystallizing, washing and purification, the lead chloride product with purity of 99% is obtained.

Key words: sintering dust; coordination leaching; resource utilization; lead recycling