降低锌电积外排酸雾的生产实践

Production practice to minimize acid mist discharge from zinc electrowinning

湿法炼锌过程中酸雾的产生主要发生在锌电积车间,酸雾会刺激人的呼吸道与皮肤,腐蚀人的牙齿,污染周边空气和土壤。丹霞冶炼厂针对锌电积车间外逸酸雾严重的问题,通过严控新液质量,改进电解槽通风系统,改进风冷塔布液系统、捕滴器,并增加捕沫器等措施,使得外排酸雾减少了99.5%以上,厂房四周的酸雾浓度小于0.025 mg/m^(3),风冷塔外排酸雾0.3 mg/m^(3),不但达到了国家限值排放的要求,而且在行业内遥遥领先。同时,由于风冷塔增高、喷淋系统改进,风冷塔的降温幅度也达到5~6℃,满足了锌电积正常稳定生产的要求。

Generation of acid mist mainly occurs during electrowinning of the hydrometallurgical zinc refining process.Acid mist irritates respiratory tract and skin,corrodes teeth and contaminates ambient air and soil.Fugitive acid mist in zinc electrowinning operations has been a major concern in Danxia Refinery.Control measures are taken including strict control of the quality of purified solution,optimized ventilation system of electrolysis cells,improved liquid distribution system and spray trap of air-cooled tower and provision of foam trap.As a result,acid mist discharge to atmosphere decreases by more than 99.5%.Ambient acid mist concentration drops to lower than 0.025 mg/m^(3) and acid mist discharge from air-cooled tower declines to 0.025 mg/m^(3).It is not only in compliance with state discharge limits but also far ahead in the industry.Meanwhile,the increased height and optimized spray system of the air-cooled tower improves the cooling range to 5-6℃,which meets the requirements of normal and stable operations of zinc electrowinning.