降低铅冶炼底吹炉高铅渣含硫量的生产实践

Production Practice of Reducing the Sulfur Content of High Lead Slag in Bottom Blown Furnace of Lead Smelting

某铅冶炼厂采用“富氧底吹氧化-氧气侧吹还原”工艺进行粗铅冶炼,底吹炉产出的高铅渣含硫量较高,达到1.3%~1.6%,对后续尾气脱硫系统造成一定影响,环保处理成本升高。为了解决该问题,本文结合理论和生产实践分析了铅冶炼底吹炉高铅渣含硫高的主要原因。高铅渣中的硫主要以硫酸根形态存在,这些硫酸根一部分来自入炉物料中的硫酸盐类铅物料,另一部分则是在熔炼过程中由硫化铅精矿发生氧化反应生成的。降低高铅渣含硫量的主要途径是提高熔池熔炼的温度和降低系统中SO_(2)的分压。结合生产实践从渣型、氧料比、入炉粒矿含硫、系统SO_(2)分压等方面探讨了降低底吹炉高铅渣含硫量的途径和方法。在含铅渣料搭配比例30%左右,控制渣温1050~1100℃,控制渣型FeO/SiO_(2)1.4~1.8,CaO/SiO_(2)0.4~0.6;氧料比100~110 Nm^(3)/t,入炉粒矿有效硫12.5%~13.5%及适当负压等相关工艺参数组合条件下,可使高铅渣残硫保持在1.2%以下。

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 SO_(2)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 SO_(2)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/SiO_(2)1.4~1.8,CaO/SiO_(2)0.4~0.6,oxygen-to-feed ratio of 100~110 Nm^(3)/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%.