采用碳基还原实现氧化锌烟尘中铅锡与锌的同步分离回收,考察了预处理脱氟氯硫(Na2CO3碱洗、煅烧)和配加添加剂(CaO、膨润土)对碳基还原过程铅锡挥发率的影响。结果表明,当烟尘未经预处理,实验条件为温度1300℃、焦粉用量14.04%和保温时间120min时,铅锡挥发率分别为78.58%和95.97%。同一实验条件下,相比于无预处理,碱洗和煅烧均能使铅锡挥发率降低。烟尘经碱洗后,铅锡挥发率分别降至12.97%、16.99%;煅烧使铅锡挥发率分别降至30.46%、57.83%。CaO用量增加有利于降低铅锡挥发率,当CaO用量为5%时,铅锡挥发率分别降至32.16%、57.7%;膨润土用量增加促进铅挥发率的降低,对锡挥发率无明显影响,当膨润土用量为5%时,铅锡挥发率分别降至37.44%、83.25%。采用该工艺,最终同时获得铅锡合金(Pb>70%,Sn>5%)和粗锌(Zn>63%,Pb>9%)。
A carbothermic reduction peocess was used to achieve the simultaneous separation and recovery of lead, tin and zinc in zinc oxide dust. The effects of pretreatment to remove fluorine, chlorine and sulfur (Na2CO3-alkali washing and calcination) and adding additives (CaO and bentonite) on the volatilization rate of lead and tin in carbothermic reduction process were investigated. The results show that the volatilization rate of lead and tin were 78.58% and 95.97% respectively when the dust was not pretreated and the conditions were the temperature of 1300℃, the reductant dosage of 14.04% and the holding time of 120min. Under the same conditions, alkali washing and calcination could reduce the volatilization rate of lead and tin. After alkali washing, the volatilization rate of lead and tin reduced to 12.97% and 16.99% respectively. After calcination, the volatilization rate of lead and tin reduced to 30.46% and 57.83% respectively. Increasing the dosage of CaO is beneficial to reduce the volatilization rate of lead and tin. When the dosage of CaO was 5%, the volatilization rate of lead and tin drops to 32.16% and 57.7% respectively. Increasing the dosage of bentonite promotes the volatilization of lead, but has no obvious effect on volatilization of tin. When the dosage of bentonite was 5%, the volatilization rate of lead and tin drops to 37.44% and 83.25% respectively. Using this process, lead-tin alloy (Pb>70%,Sn>5%) and crude zinc (Zn>63%,Pb>9%) are finally obtained at the same time.