Chen Hongliang, Liu Renlong, Shu Jiancheng, Li Wensheng
a College of Chemistry and Chemical Engineering, Chongqing University , Chongqing , P. R. China.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2015;50(12):1282-90. doi: 10.1080/10934529.2015.1055157.
Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)2SO4 and (NH4)3H(SO4)3. The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8 wt.% added CaO, 60°C, 800 mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).
电解锰渣（EMR）的浸出试验表明，其中高含量的可溶性锰和氨氮带来了很高的环境风险。本文报道了在氧化钙辅助下利用空气同时脱除氨氮并沉淀锰的结果。氨氮的脱除率随氧化钙用量、空气流速以及电解锰渣浆液温度的增加而提高。脱除的氨氮被硫酸溶液吸收，形成可溶性的硫酸铵[(NH₄)₂SO₄]和硫酸氢铵[(NH₄)₃H(SO₄)₃]。影响可溶性锰沉淀的主要参数是氧化钙的添加量和浆液温度。综合考虑这两个方面，高效的操作条件应为添加8 wt.%的氧化钙、温度60°C、空气流速800 mL min⁻¹以及反应时间60分钟。在此条件下，99.99%的可溶性锰以四氧化三锰（Mn₃O₄）的形式沉淀，这通过X射线衍射（XRD）和扫描电子显微镜-能谱分析（SEM-EDS）得以证实。此外，氨氮的脱除率为99.73%。浸出试验表明，处理后的电解锰渣中浸出的有毒物质浓度符合中国的综合废水排放标准（GB8978-1996）。
