Sustainable Mining and Metallurgy

A lead smelter adopts the process of “oxygen-enriched bottom blown oxidation-oxygen side blowing reduction” for crude lead smelting. The high lead slag produced by the bottom blown furnace has a high sulfur content of 1.3%~1.6%, which has a certain impact on the subsequent tail gas desulfurization system and increases the cost of environmental protection treatment. In order to solve this problem, this paper analyzed the main reasons for the high sulfur content of high lead slag in lead smelting bottom blown furnace based on theory and production practice. It can be seen that the sulfur in high lead slag mainly exists in the form of sulfate. Some of these sulfates come from the sulfate lead materials in the furnace materials, and the other part is generated by the oxidation reaction of lead sulfide concentrate in the smelting process. The main way to reduce the sulfur content of high lead slag is to increase the temperature of molten pool smelting and reduce the partial pressure of SO₂ in the system.Combined with the production practice, the ways and methods to reduce the sulfur content of high lead slag in bottom blown furnace were discussed from the aspects of slag type, oxygen-to-material ratio, sulfur content in granular ore and SO₂ partial pressure of the system. Under the condition such as lead-containing slag material ratio of about 30%, slag temperature 1050~1100℃, slag type FeO/SiO₂ 1.4~1.8, CaO/SiO₂ 0.4~0.6, oxygen-to-feed ratio of 100~110Nm³/t, effective sulfur content in pellet ore12.5%~13.5% and appropriate negative pressure, the residual sulfur content of high lead slag can be kept below 1.2%.