含COD高盐废水冷冻脱硝-蒸发浓缩技术的开发研究  

Research and development of freezing denitrification-evaporation concentration technology for COD high salt wastewater

作　　者：曹敏 付国燕 刘苏宁 李诺 孙宁磊[1] CAO Min;FU Guo-yan;LIU Su-ning;LI Nuo;SUN Ning-lei

机构地区：[1]中国恩菲工程技术有限公司,北京100038

出　　处：《中国有色冶金》2021年第3期85-90,共6页China Nonferrous Metallurgy

摘　　要：有色金属湿法冶金废水中含有大量的有机物及硫酸盐、氯化钠等盐分,冷冻脱硝技术利用固液相平衡原理实现冷冻分离,可使低温条件下溶解度较低的溶质析出,得到高纯盐结晶和浓缩废水,但剩余浓缩废水中依然含有高浓度的Na_(2)SO_(4)、NaCl与COD,依然不能外排。本文针对含Na_(2)SO_(4)与Na Cl两种物质的含COD高盐废水,提出了冷冻脱硝-蒸发浓缩技术,并对冷冻脱硝温度和NaCl初始含量对产物的影响进行了分析,得出以下结论:在0~10℃冷冻温度范围内,冷冻结晶中COD残留量低于30%,最佳冷冻温度为8℃;Na_(2)SO_(4)/NaCl质量含量比值越高,析出的Na_(2)SO_(4)结晶纯度越高;利用氯化钠-硫酸钠-水三相体系中物质浓度比和溶解度的不同,有效实现了硫酸钠与氯化钠的分离,实验产物为芒硝、Na_(2)SO_(4)结晶及杂盐产品。采用此技术处理Na_(2)SO_(4)及粗盐工业产品,可实现含COD高盐废水资源化利用,并实现零污染排放。Non-ferrous metal hydrometallurgical wastewater contains a large amount of organic matter,sulfate,sodium chloride and other salts.Frozen denitrification technology uses the principle of solid-liquid equilibrium to achieve freezing separation,which can precipitate low-solubility solutes under low temperature conditions to obtain high-purity salt crystallization and concentrated wastewater,but the remaining concentrated wastewater still contains high concentrations of Na_(2)SO_(4),NaCl and COD.Still can’t discharge outside.In this paper,freezing denitrificationevaporation concentration technology is used to treat COD high-salt wastewater containing Na_(2)SO_(4) and NaCl,and the effects of freezing denitrification temperature and initial concentration of NaCl on the product are analyzed.Concluded as follow:In the freezing temperature range of 0~10℃,the residual COD in frozen crystal is less than30%,and the best freezing temperature is 8℃;The higher the ratio of Na_(2)SO_(4)/NaCl mass content,the higher the purity of the precipitated Na_(2)SO_(4) crystals;Taking advantage of the difference in the concentration ratio and solubility of the substances in the sodium chloride-sodium sulfate-water three-phase system,the separation of sodium sulfate and sodium chloride is effectively realized.The experimental products are Glauber’s salt,Na_(2)SO_(4) crystals and hetero salt products.Using this technology to treat Na_(2)SO_(4) and crude salt industrial products can realize the resource utilization of COD-containing high-salt wastewater,and realize zero pollution discharge.

关 键 词：含COD高盐废水 冷冻脱硝 蒸发浓缩 芒硝纯度 Na_(2)SO_(4)纯度 冷冻温度 冷冻电耗 NaCl初始含量 

分 类 号：TF803.2[冶金工程—有色金属冶金] X758[环境科学与工程—环境工程]