中和—絮凝法回收硝酸型退锡废水中的锡

将传统的中和法和絮凝法相结合,采用中和—絮凝法回收硝酸型褪锡废水中的锡,考察了反应终点体系pH、碱液浓度、絮凝剂浓度等因素对锡回收效果的影响。实验结果表明,在NaOH溶液浓度为6 mol/L、反应终点体系pH为0.8、聚丙烯酰胺溶液质量浓度为3 g/L的工艺条件下,可得到干基锡含量54.6%（w）的高品位锡泥。与传统的单一中和/絮凝法相比,采用中和—絮凝法不仅可以有效提高生产效率,而且减少了碱液和絮凝剂用量,回收锡之后体系中大量的硝酸可进一步回收利用。

Recovery of tin from spent nitric tin-stripping solution by neutralization - flocculation process

Tin in spent nitric tin-stripping solution was recovered by neutralization - flocculation process. The factors affecting tin recovery were investigated,such assystem pH at reaction end point,alkali liquor concentration and flocculant concentration. The experimental results show that the tin sludge with 54.6%（w） of dry base content can be obtained under the process conditions of NaOH solution concentration 6 mol/L,reaction end point system pH 0.8 and polyacrylamide solution mass concentration 3 g/L. Compared with the traditional single neutralization/flocculation process,the neutralization - flocculation process can not only effectively improve the production efficiency,but also reduce the amount of alkali liquor and flocculant,furthermore,a large amount of nitric acid in the tin-recovered system can be reused.