负压蒸发和吹脱处理铅锌冶炼污酸废水的试验研究

Treatment of Waste Acid Water from the Lead-zinc Smelting Industry by Vacuum Evaporation and the Stripping Method

污酸废水酸性强,重金属离子种类多,处理难度大,目前常用的处理方法主要有硫化-石灰中和法、混凝沉淀法、离子交换法、电渗析法等,但这些处理方法存在易产生大量难处理的二次危险废物,出水水质难以达到回用要求等缺点。针对铅锌冶炼污酸废水的特性,通过负压蒸发试验和吹脱试验,研究了采用负压蒸发回收水资源和吹脱除氟、氯的可行性,并对负压蒸发和吹脱过程的主要影响因素及其反应动力学进行了研究。试验结果表明:负压蒸发试验加热温度为100℃、真空度为0.095 MPa、浓缩倍数为3倍左右时,冷凝液中氟、氯离子的浓度在50mg/L以下,符合工业回用水标准;吹脱试验加热温度为100℃、风温为100℃、吹脱终点的酸度为21.5时,污酸废水中氟、氯离子可以达到较理想的去除效果,氟的去除率在95%以上,氯的去除率在90%以上;反应动力学研究表明,负压蒸发和吹脱过程均符合拟一级动力学模型。负压蒸发法和吹脱法处理污酸废水具有较好的应用前景。

The treatment of contaminated acid water is difficult because of strong acidity and various heavy metal ions.Sulfide precipitation,lime neutralization,coagulant sedimentation,ion-exchange and elector-dialysis methods are being used at present.Those methods have some deficiencies such as producing a lot of hazardous,unwieldy solid wastes,and the unqualified effluent for reusing.This paper studies the treatment of vacuum evaporation and the feasibility of recovering water and valuable metals according to characteristics of waste acid from lead-zinc smelting.The paper explores the feasibility of recycling water resources under the condition of vacuum evaporation and removal of fluorine and chlorine by the stripping method.The results show that fluorine and chloride have good removal rates from contaminated acid by vacuum evaporation.With temperature at 100℃,vacuum degree at 0.095 MPa and enrichment ratio in around 3.0,the concentration of fluorine,chlorine in liquor condensate are both below50 mg/L which meets the reuse standards.Moreover,the removal rate of fluorine can reach 95%and that of chlorine can reach 90%in condensate liquor with the hot air temperature of 100℃,the heating temperature of 100℃,and the ending acidity of 21.5.Through the kinetic analysis,negative pressure evaporation and stripping experiments are in accordance with the pseudo-first order kinetic equations.Overall,the results indicate that vacuum evaporation and stripping has good application prospects to treat waste acid water from the lead-zinc smelting industry.