不锈钢酸洗废水中有价组分梯级分离及酸再生研究

不锈钢酸洗废水通常采用石灰中和,产出大量危险固体废弃物(硫酸钙渣)。对不锈钢酸洗废水有价组分梯级分离及硫酸再生硝酸/耦合制备硫酸钙晶须展开研究。考察了高酸环境氟离子脱除、有价金属梯级分离及酸再生三个工序不同因素对试验结果的影响。借助SEM对酸再生过程耦合产出的硫酸钙晶须形貌进行分析,确定了各工序的最佳工艺条件。结果表明,氟离子在高酸环境下脱除率97%;铁、镍和铬的选择性沉淀率均99.9%;硝酸高效再生并耦合产出硫酸钙晶须,硝酸再生率95%,再生硝酸浓度超过143g/L。为不锈钢酸洗废水处理提供了一种可靠的新技术,且工艺稳定。

Study on Gradient Separation of Targeted Components and Acid Regeneration from Stainless Steel Pickling Wastewater

Stainless steel pickling liquor is usually neutralized by lime, which produces a large amount of hazardous solid waste (calcium sulfate slag). Gradient separation of targeted components in stainless steel pickling liquor, regeneration of nitric acid by sulfuric acid and coupling synthesis calcium sulfate whiskers with high aspect ratio were studied. Effects of factors on experimental results during fluoride ion removal in high acid environment, gradient separation of valuable metals, and acid regeneration were systematically investigated. Morphology of calcium sulfate whiskers synthesized by coupling reaction in acid regeneration was analyzed by SEM to determine the optimum technological conditions of each process. The results show that fluoride ion removal rate under high acid environment is 97% above, precipitation rate of iron, nickel and chromium is all 99.9% above. Nitric acid is efficiently regenerated and calcium sulfate whiskers are synthesized by coupling reaction. Regeneration rate of nitric acid is 95% above and concentration of nitric acid regenerated exceeds 143 g/L. A reliable and stable new technology to treat stainless steel pickling wastewater is provided.