低温焙烧法还原废铅膏中PbO_(2)的研究

Study on Reduction of PbO_(2) in Waste Lead Paste by Low Temperature Roasting

传统火法冶金工艺可将PbO_(2)直接还原为铅,然而这需要高温条件且易产生铅挥发等问题。湿法冶金虽可在低温下高效地将PbO_(2)还原为二价铅化合物,但需要消耗较多的强酸和还原试剂。提出了一种PbO_(2)绿色转化的方法,利用(NH_(4))_(2)SO_(4)在低温下分解成NH_(4)HSO_(4)将PbO_(2)还原为PbSO_(4)。结果表明,NH_(4)HSO_(4)和PbO_(2)反应过程会生成中间产物Pb(NH_(4))_(2)(SO_(4))2。废铅膏与(NH_(4))_(2)SO_(4)反应的最佳条件为:摩尔比n(SO_(4)^(2-))/n(T_(Pb))=1、焙烧温度340℃、焙烧时间1.5 h,在该条件下PbO_(2)的还原率为96.64%,焙烧产物的PbSO_(4)含量为96.38%。

Conventional pyrometallurgical processes can directly reduce PbO_(2) directly to lead,however,this requires high temperature conditions and is easy to cause problems such as lead volatilization.Although hydrometallurgy can efficiently reduce PbO_(2) to divalent lead compounds at low temperatures,it requires the consumption of strong acids and reduction reagents.A green conversion method of PbO_(2) was proposed,which utilized(NH_(4))_(2)SO_(4) decompose into NH_(4)HSO_(4) at low temperatures to reduce PbO_(2) to PbSO_(4).The results indicate that the reaction process between NH_(4)HSO_(4) and PbO_(2) will generate the intermediate product Pb(NH_(4))_(2)(SO_(4))2.The reduction rate of PbO_(2) is 96.64%,and PbSO_(4) content of the roasting product is 96.38% under the optimum conditions for the reaction of spent lead paste with(NH_(4))2 SO_(4) including molar ratio of n(SO_(4)^(2-))/n(T_(Pb))=1,roasting temperature of 340℃,and roasting time of 1.5 h.