硫化铅矿闪速熔炼过程的热力学分析

Thermodynamic analysis of lead sulfide flash smelting process

基于最小吉布斯自由能原理,建立硫化铅矿闪速熔炼过程多相平衡热力学模型,考察熔炼温度(T)、吨矿氧量(VOVPTO)对粗铅含硫量、炉渣含铅量、烟气含铅量及铅在各平衡相中分配比的影响。结果表明:对一定用量和一定成分的硫化铅矿,随着T和VOVPTO的增大,粗铅含硫量可降至0.1%(质量分数)以下,但过高的VOVPTO会使渣含铅量升至60%(质量分数)以上,铅在粗铅中的分配比低于30%(质量分数);烟气中的铅主要以PbS形式存在,其含量随着T的升高及VOVPTO降低而增高。综合考虑铅的直收率及产物处理的难易程度,闪速炉直接炼铅应采取分区分步熔炼方式,先在氧化区制"低硫铅",然后在还原区造"低铅渣",且氧化区熔炼温度宜较低。

Based on the principle of Gibbs free energy minimization,the thermodynamic model of the lead sulfide flash smelting multi-phase equilibrium system was built.Then,the effects of the smelting temperature（T） and the oxygen volume per ton ore（VOVPTO） on the lead distribution rate and the equilibrium compositions of crude lead,slag and gas were studied.The results show that,for the lead sulfide with a certain amount and a certain composition,the sulfur content in the crude lead can be reduced to be less than 0.1% with the rise of T and VOVPTO,but the lead content in the slag exceeds 60% and the lead distribution rate in the crude lead is less than 30% when VOVPTO is excessive.The lead volatile in the gas,mainly in the form of PbS,rises with the rise of T and the decrease of VOVPTO.Therefore,taking into account the recovery rate of lead and the processing difficulty of products,the lead flash direct smelting furnace should be divided into oxidation and reduction zones,and the low-sulfur lead is produced firstly in the oxidation zone,the low-lead slag is produced secondly in the later zone,and the oxidation smelting temperature should be low.