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中南大学学报(自然科学版)

Journal of Central South University

第43卷    第5期    总第213期    2012年5月

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文章编号:1672-7207(2012)05-1610-06
钼酸铵溶液镁盐沉淀法除砷的热力学分析
杨亮,赵中伟,何利华,霍广生,陈爱良

(中南大学 冶金科学与工程学院,湖南 长沙,410083)

摘 要: 湿法处理镍钼矿所得钼酸铵溶液砷含量较高。针对镁盐沉淀法除砷的工艺,进行热力学分析。根据同时平衡原理和质量守恒定律,进而绘制在25 ℃ 时Mg-NH4-As-H2O系热力学平衡图,并考察工艺参数对除砷的影响。研究结果表明:溶液中总氨浓度的升高及镁盐用量增大,平衡时砷含量降低。当钼酸铵溶液中 [N]T=5 mol/L,[As]T=0.1 mol/L, [Mg]T=0.12 mol/L时,整个pH范围存在4个平衡固相的稳定区即MgHAsO4稳定区(4.0<pH<6.0),MgNH4AsO4稳定区(6.0<pH<9.5),MgNH4AsO4和Mg(OH)2稳定区(9.5<pH<11.7)及Mg(OH)2稳定区(pH>11.7);当溶液pH为9时,砷质量浓度可除至2×10-6 g/L,溶液中残留镁浓度为0.02 mol/L。

 

关键字: 镍钼矿;除砷;砷酸铵镁;热力学

Thermodynamics analysis on removal of arsenic from ammonium molybdate solution by chemical precipitation with magnesium salt
YANG Liang, ZHAO Zhong-wei, HE Li-hua, HUO Guang-sheng, CHEN Ai-liang

School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China

Abstract:The coarse ammonium molybdate solution obtained by hydrometallurgical treatment of Ni-Mo ore contains high arsenic. Thermodynamic analysis of removing arsenic from the ammonium molybdate solution with addition of MgCl2 was studied. According to the principle of simultaneous equilibrium and the law of conservation of mass, thermodynamic equilibrium diagrams of Mg-NH4-As-H2O system were established at 25 ℃. The effect of technical conditions on removal of arsenic was investigated. The results indicate that the concentration of arsenic decreases with the increase of total ammonium concentration and dosage of MgCl2. There are four stable areas of various solid phases in the whole pH of the system, when total ammonium is 5 mol/L, total arsenic is 0.1mol/L and total Mg is 0.12 mol/L in the system. The first one is MgHAsO4 (4.0<pH<6.0), the second one is MgNH4AsO4 (6.0<pH<9.5), the third one is MgNH4AsO4 and Mg(OH)2 (9.5<pH<11.7), and the forth one is Mg(OH)2 (pH>11.7). Adjusting the pH to 9, the arsenic concentration can be thermodynamically decreased to 2×10-6 g/L and residual magnesium concentration is 0.02 mol/L in the solution.

 

Key words: Ni-Mo ore; arsenic removal; MgNH4AsO4; thermodynamics

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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