硫铁矿制酸净化工序废稀酸回用的探讨

Discussion on reuse of waste dilute acid from purification process during producing sulfuric acid by pyrite

为了考察硫铁矿制酸净化工序产生的废稀酸回用于湿法磷酸萃取系统的可行性问题,将经简单沉淀和经深度处理的废稀酸分别回用于制取磷酸。结果表明,未经深度处理的废稀酸直接回用将导致磷酸产品中砷及重金属元素铅、镉的浓度明显升高,分别升高34.13、0.22、0.50倍;废稀酸经化学沉淀法深度处理后,砷及重金属元素达到GB 8978—1996《污水综合排放标准》中相关指标的要求,将其回用后所得的磷酸产品中砷及重金属元素浓度不会升高。选择合适的工艺将净化工序产生的废稀酸处理达标后再回用于湿法磷酸生产系统,能够同时取得良好的经济效益和环保效益。

For the purpose of investigating the feasibility of reusing waste dilute acid from purification process of sulfuric acid production by pyrite to extract wet-process phosphoric acid, preliminarily precipitated waste dilute and advanced treated waste dilute was reused to produce phosphoric acid. The results showed that, directly reusing the waste dilute acid without deep treatment in sulfuric acid producing system may cause obvious in- crease of arsenic and heavy metal elements such as lead and cadmium concentrations in the phosphoric acid product, which were respectively 34.13, 0.22 and 0,50 times higher than before. The concentrations of arsenic and heavy metal elements in the advanced treated waste dilute acid met the requirement of GB 8978--1996 Integrated wastewater discharge standard, therefore, reuse it to produce phosphoric acid, the concentrations of arsenic and heavy metal elements in the product would not be increased. It was suggested that waste dilute acid from purification process of phosphoric acid production by pyrite could be reused in phosphoric acid producing system when its quality up to the standard after being treated by proper process, which could achieve good eco-nomic and environmental benefits.