碳酸盐体系中砷酸复盐选择性沉砷研究  

Study on selective arsenic precipitation by arsenate double salt in carbonate system

作　　者：田佳 王宇峰 彭竣 张荥斐 孙伟[1] 刘勇[3] 韩海生[1] 胡文吉豪 沈吉峰 李光梅 TIAN Jia;WANG Yufeng;PENG Jun;ZHANG Xingfei;SUN Wei;LIU Yong;HAN Haisheng;HU Wenjihao;SHEN Jifeng;LI Guangmei(School of Minerals Processing and Bioengineering,Central South University,Changsha 410083,China;Tidu Environmental Protection Co.Ltd.,Lengshuijiang 417500,China;Hunan Gold Group Co.Ltd.,Changsha 410083,China)

机构地区：[1]中南大学资源加工与生物工程学院,湖南长沙410083 [2]冷水江锑都环保有限责任公司,湖南冷水江417500 [3]湖南黄金集团有限责任公司,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2023年第1期1-12,共12页Journal of Central South University:Science and Technology

基　　金：2022博士后创新人才支持计划(BX20220354);十三五重点研发计划(2020YFC1807800,2018YFC1901601,2018YFC1901602)。

摘　　要：针对碳酸盐体系下常规金属砷酸盐沉淀法无法高效选择性除砷这一难题,提出通过砷酸复盐选择性沉淀实现砷酸盐与碳酸盐选择性分离的方案。基于25℃时Mg^(2+)-NH_(4)^(+)-AsO_(4)^(3-)-CO_(3)^(2-)-OH^(-)-H_(2)O体系的热力学平衡图,研究通过砷酸复盐(MgNH_(4)AsO_(4))沉淀实现砷酸盐和碳酸盐选择性分离的理论基础,并结合具体砷酸复盐沉砷实验,分析体系中CO_(3)^(2-),Mg^(2+)和NH_(4)^(+)初始质量浓度对最终除砷效率及砷渣品位的影响。研究结果表明:增大CO_(3)^(2-)质量浓度会降低砷酸复盐除砷率和砷渣品位,增加Mg^(2+)初始质量浓度虽可提高除砷率,但会增加砷渣中MgCO_(3)的摩尔分数,进而降低砷渣品位;增大NH_(4)^(+)初始质量浓度不仅能够提高除砷率,而且还会增加沉淀中MgNH_(4)AsO_(4)的摩尔分数,从而提高砷渣品位。在Na_(2)CO_(3)质量浓度为150 g/L的含砷溶液中,控制Mg^(2+)与As(Ⅴ)物质的量比为1.2:1.0,NH_(4)^(+)与As(Ⅴ)物质的量比为4.0:1.0,砷酸复盐矿化沉淀的除砷率和砷渣品位分别达到90.83%和29.75%。In view of the difficulty that the conventional metal arsenate precipitation method can not remove arsenic efficiently and selectively in carbonate system,a scheme of selective separation of arsenate and carbonate by arsenate double salt selective precipitation was proposed.Based on the thermodynamic equilibrium diagram of Mg^(2+)-NH_(4)^(+)-AsO_(4)3--CO_(3)^(2-)-OH^(-)-H_(2)O system at 25℃,theoretical basis was studied for the selective separation of sodium arsenate and sodium carbonate through the mineralization and precipitation of arsenate double salt,and the effects of initial concentrations of CO_(3)^(2-),Mg^(2+)and NH_(4)^(+)on the final content and proportion of each component in the system were also studied.The results show that increasing the mass concentration of CO_(3)^(2-)will reduce the arsenic removal rate of arsenate double salt and the grade of arsenic slag.Increasing the initial mass concentration of Mg^(2+)will increase the arsenic removal rate,but will increase the molar fraction of MgCO_(3)components in arsenic slag,thereby reducing the grade of arsenic slag.Increasing the initial mass concentration of NH_(4)^(+)will not only improve the arsenic removal rate,but also increase the molar fraction of MgNH_(4)AsO_(4)components in precipitation,thereby increasing the grade of arsenic slag.In the arsenic solution with Na_(2)CO_(3)concentration of 150 g/L,by controlling the mole ratio of Mg^(2+)and As(V)at 1.2:1.0 and the mole ratio of NH_(4)^(+)and As(V)at 4.0:1.0,the arsenic removal rate and arsenic slag grade can reach 90.83%and 29.75%,respectively.

关 键 词：含砷废水 高碱盐 热力学 砷酸复盐 砷碱分离 

分 类 号：X505[环境科学与工程—环境工程]