Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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第18卷    第2期    总第107期    2008年2月




(中南大学 冶金科学与工程学院,长沙 410083)

摘 要:

通过热力学计算,绘制了25 ℃下白钨矿在总碳浓度为1 mol/L Na2CO3溶液中各主要溶解组分的lg c—pH图,以及白钨矿在不同总碳浓度下Na2CO3溶液中 和 的lg c—pH图。利用这些热力学平衡图对Na2CO3分解白钨矿的工艺条件进行了分析,认为溶液中 浓度直接影响白钨矿分解,而当碱度较低时,Na2CO3将水解生成 ,从而降低 浓度,进而降低白钨矿的分解率;故在工业实践中,为使钨最大限度地转入溶液,除了保证足够的Na2CO3用量,还必需添加NaOH以维持一定碱度。利用热力学分析所得结论,重新解释了前人的实验现象,认为以过多的NaOH代替Na2CO3造成钨浸出率回落的原因在于,溶液中 浓度的较大幅度下降,而不是钨矿中脉石分解所引起的Na2CO3消耗。


关键字: 白钨矿;碳酸钠分解;热力学;浓度对数图

Thermodynamics on soda decomposition of scheelite
ZHAO Zhong-wei, CAO Cai-fang, LI Hong-gui

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

Abstract: The lg c—pH diagrams at 25 ℃ for containing ions when the total carbon concentration being 1 mol/L are established according to thermodynamic calculation. The lg c—pH diagrams for and at different total carbon concentrations are also established. Using these diagrams, thermodynamic analysis is carried out to show the effect of technical conditions on soda decomposition of scheelite. It appears that the concentration of has direct effect on soda decomposition of scheelite. When the alkalinity is low, will hydrolyze to , accordingly the decomposition rate of scheelite becomes lower because of the decrease of . So in order to get higher leaching rate in industry practice, it is necessary to use enough amount of soda to serve as digestion reagent and, certain amount of NaOH to maintain high enough alkalinity. A re-explanation of experimental phenomenon reported in literature is derived, which shows that the reason causing the decrease of tungsten extraction when using overhigh degree of substitution of NaOH for Na2CO3 lies in the sharp decrease of the concentration, not the increasing attack of gangue constituents, which would consume Na2CO3 that otherwise would have been available to digest scheelite.


Key words: scheelite; soda decomposition; thermodynamics; concentration logarithm diagram

ISSN 1004-0609
CN 43-1238/TG

ISSN 1003-6326
CN 43-1239/TG

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