碱性谷氨酸钠体系处理低品位氧化锌矿的基础理论和工艺

【作者】 任晋；

【导师】 杨天足；

【作者基本信息】 中南大学 ， 有色金属冶金， 2010， 硕士

【摘要】 本文针对高碱性脉石型低品位氧化锌矿的处理现状,提出了碱性谷氨酸钠体系处理高碱性脉石型氧化锌矿的新工艺。该工艺可以消除高碱性脉石对锌资源有效利用的影响,而且实验过程无环境污染问题。论文的主要研究内容和结果如下：根据配位化学理论绘制了谷氨酸根(Glu2-)和碳酸根(CO32-)在溶液中的形态分布图,采用双平衡法研究了Zn(II)-Glu2--CO32--H2O体系中锌(Ⅱ)的配合平衡热力学,并绘制了谷氨酸钠浓度在0～5mol·L-1范围和pH在7-14范围内变化时的热力学平衡图。结果表明,在一定的谷氨酸钠浓度下,当pH=10时,溶液中总锌浓度达到最大值。用实验验证了热力学计算结果,锌离子浓度理论计算值与实验值之间相对误差的绝对平均值为11.39%；同时研究了Ca、Mg等主要杂质元素在Zn(Ⅱ)-Glu2--CO32--H2O体系处理氧化锌过程中的溶解行为和平衡规律,结果表明,当7<pH<12时,溶液中总钙、总镁浓度随着pH的增大而降低,当pH>12时,溶液中的总钙和总镁浓度逐渐增加。研究了碱性谷氨酸钠浸出氧化锌矿的工艺条件,在液固比5：1、谷氨酸钠浓度1.5mol·L-1、pH=9、反应时间5h、反应温度80℃、不加入氧化剂的优化条件下浸出两批氧化锌矿,锌的浸出率分别为64.52%、66.60%,浸出液的锌浓度分别为7.97g·L-1、7.90g·L-1。浸出液采用锌粉置换法净化除去Cu、Pb、Cd等杂质,在常温、锌粉加入量3g·L-1、净化时间1h的条件下,溶液中的Cu、Pb、Cd含量分别为1.1.88mg·L-1、1.88mg·L-1、0.88mg·L-1。探索了从浸出液中提取锌的工艺研究,通过循环浸出-净化-电积提锌工艺和直接沉锌工艺的对比可知,直接沉锌工艺为较好的提锌工艺。以磷酸为沉淀剂从净化后浸出液中直接沉锌得到磷酸锌钠,并对最优条件下制得的产品进行粒度分析和扫描电镜分析可知,磷酸锌钠的粒度呈正态分布,平均粒径为4.146μm；磷酸锌钠的形状基本为球形,没有气孔。更多还原

【Abstract】 In this work,a new process of treating low grade zinc ores bearing high basic gangues in the alkaline solution of monosodium glutamate was proposed in accordance with the existing zinc metallurgical way. The influence of high basic gangues to effectively extract zinc could be eliminated by the technique,and the pollution problem could be avoided in the process.The basic contents and results were shown as follows:Species distribution disgrams of glutamate (Glu2")and carbonate ion(CO32-)in the solution were obtained based on the coordination chemistry theory.Thermodynamics of Zn(Ⅱ)complex equilibrium in the system of Zn(Ⅱ)-Glu2--CO32--H2O were studied by the double equilibrium theory.When the concentration of monosodium glutamate and pH value varied accordingly in ranges of 0～5mol·L-1 and 7～14,the equilibrium thermodynamic diagrams were constructed.It is indicated that total zinc concentration reaches the maxium value when the pH value is 10 under a certain monosodium glutamate concentration.The theoretical calculation results were testified by solubility experiments.The absolute average value of relative error between them is 11.39%.Meanwhile,the behavior and equilibrium law of major impurities such as Ca、Mg were studied in the leaching of zinc oxide ores in the Zn(Ⅱ)-Glu2--CO32--H2O system.The results show that the total concentration of calcium and magnesium gradually decreases when th pH value changes in ranges of 7～12,while increases when the pH value reaches above 12.The technique conditions of leaching zinc oxide ores were studied in the alkaline solution of monosodium glutamate.Two batches of zinc oxide ores were leached under the following optium conditions:the ratio of liquid to solid being 5:1,monosodium glutamate concentration of 1.5 mol·L-1,pH value of 9,leaching time for 5 h at 80℃without oxidant.The leaching yield of zinc was 64.52% and 66.60%,and the concentration of zinc in the leaching solution was 7.97g·L-1、7.90g·L-1,respectively.The leaching solution was purified to remove impurities such as Cu、Pb、Cd with zinc powder displacement. When the purification process followed the condition of 1 h at ambient temperature in the presence of 3g·L-1 zinc powder,the contents of Cu、Pb、Cd in the solution were 0.18mg·L-1、1.88mg·L-1 and 0.88mg·L-1,respectively.The technique conditions of extracting zinc were explored from purified leaching solutions.Compared with the technique of cycle leaching-purification-electrowinning,direct zinc precipitation technique could be a better one. Sodium zincophosphate was obtained by direct precipitation with phosphate from purified leaching solutions.The product prepared under optium conditions was characterized by laser particle sizer and scanning electron microscopy.The particle of sodium zincophosphate showed normal distribution,and the average particle size was 4.146μm;the sodium zincophosphate particle was spherical shape and had no porosity.更多还原