化学沉淀法去除稀土湿法冶炼废水中钙与高浓度氨氮研究  

Removal of Calcium and High-strength Ammonia Nitrogen from the Wastewater of Rare-earth Elements Hydrometallurgical Process by Chemical Precipitation

作　　者：王浩[1,2] 成官文[1,2] 宋晓薇[1] 徐子涵[1,2] 蒙金结[1,2] 董传强[1,2] 

机构地区：[1]桂林理工大学环境科学与工程学院,桂林541004 [2]桂林理工大学广西环境污染控制理论与技术重点实验室,桂林541004

出　　处：《环境科学》2013年第7期2718-2728,共11页Environmental Science

基　　金：广西重点实验室基金项目(桂科能1201Z028)

摘　　要：离子型稀土湿法冶炼过程中会产生大量氨氮废水,由于废水中含有大量Ca2+,而Ca2+是影响磷酸铵镁沉淀法脱氮效率的重要因素.向废水中投入Na2CO3固体生成CaCO3沉淀物,去除废水中的Ca2+,再利用磷酸铵镁(MAP)沉淀法去除废水中的氨氮.实验采用响应面实验设计方法中的中心复合设计法,利用响应面分析法对磷酸铵镁沉淀法反应参数进行优化,得到最优反应条件及最优反应条件下沉淀产物.利用扫描电子显微镜(SEM)及X射线衍射(XRD)对最优反应条件下两种沉淀物进行分析.结果表明,当n(Ca2+)∶n(CO23-)=1∶1.05,搅拌速率为1 500 r.min-1,反应时间为30 min时,Ca2+去除率接近100%;对除钙后废水进行磷酸铵镁法脱氮处理的最优反应条件为:pH=9.03,n(Mg)∶n(N)=1.20,n(P)∶n(N)=1.1,反应时间为30 min,搅拌速率为1 000 r.min-1,氨氮去除率达到95.40%,剩余总磷浓度为5.65 mg.L-1;沉淀物分别为纯净的CaCO3及MgNH4PO4.6H2O.A lot of high-strength ammonia nitrogen wastewater is generated in the ion-type rare-earth elements hydrometallurgical process. Magnesium ammonium phosphate （MAP） precipitation was chosen to remove the ammonia nitrogen from the wastewater after Ca2＋ was eliminated using Na2CO3 to generate CaCO3 precipitate, because the wastewater contained a lot of Ca2＋, and Ca2＋ was an important impact factor for MAP precipitation. Central composite design （CCD） is a principal response surface methodology （RSM） used in experimental design. Response surface methodology （RSM） was used to optimize the factors in MAP precipitation, achieving the optimal conditions and the precipitates under such conditions. Two kinds of precipitates were analyzed by scanning electron microscope （SEM） and X-ray diffraction （XRD）. The results showed that when n（Ca2＋）：n（CO2-3）=1：1.05, mix rate and reaction time were 1500 r·min-1 and 30 min, respectively, the removal ratio of Ca2＋ reached 100%; the optimal condition of MAP precipitation was pH=9.03, n（Mg）：n（N）=1.20, n（P）：n（N）=1.1, with a reaction time of 30 min and a mix rate of 1000 r·min-1, the removal ratio of ammonia nitrogen reached 95.40% and the residual total phosphorus concentration was 5.65 mg·L-1. SEM and XRD analysis showed that the two kinds of precipitates were pure CaCO3 and MgNH4PO4·6H2O, respectively.

关 键 词：磷酸铵镁沉淀法 响应面 除钙 稀土废水 扫描电子显微镜 X射线衍射 

分 类 号：X703.1[环境科学与工程—环境工程]