常压碱性介质预处理中低品位铝土矿应用基础研究
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摘要
针对我国特色的高硅中低品位一水硬铝石铝土矿难分解、能耗物耗高、投资大以及高碱赤泥污染严重等瓶颈问题，提出了常压下高浓碱液浸取铝土矿预脱硅新工艺，并进行了其应用基础研究与过程优化，主要创新性结果如下：
1、为提高高硅铝土矿的品位，提出了常压下高浓碱液处理铝土矿的新方法。并对此体系的溶解特性及处理效果进行了应用基础研究。实验研究结果表明，采用此方法进行铝土矿预脱硅反应速度快，预脱硅时间在5～20min内，远远短于其它预脱硅方法。且脱硅效果理想，足以满足拜耳法生产氧化铝工艺对铝土矿品位的要求；
2、对常压下采用高浓度的NaOH溶液直接浸取铝土矿预脱硅的主要影响因素进行了研究。结果表明：SiO_2和Al_2O_3的溶出率随温度、初始碱液浓度和液固比的增大而增大，并且Al_2O_3的溶出率受温度影响比受NaOH初始浓度影响大；
3、研究了常压下高浓碱液浸取铝土矿的动力学特性，测定了铝土矿快速预脱硅反应的表观活化能为23．4kJ／mol，反应级数为0．9，得出脱硅动力学方程为：
4、对铝硅酸钠溶液中二氧化硅和氧化铝的溶解性及稳定性进行了基础性研究。结果表明，含氧化硅的铝酸钠溶液相当稳定，亚稳区间很宽。因此，饱和的铝硅酸钠很难结晶析出，液相中氧化硅浓度降低困难。但在延长处理时间的情况下，液相中二氧化硅浓度也可以达到较低的水平，从而能够实现碱液的循环利用；
5、根据上述基础性研究结果，提出了常压下高浓碱液浸取铝土矿预脱硅新工艺的适宜流程，优化了高浓碱液浸取铝土矿预脱硅新工艺的主要工艺参数。
常压下采用高浓氢氧化钠溶液处理中低品位铝土矿进行预脱硅，液固低，苛性碱使用量少，且常压操作，有望为开发利用我国典型的中低品位铝土矿提供技术支持。
A new process of pre-desiliconization of bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure was basically investigated and optimized, which was especially developed to resolve the key problems of great investment of equipments, high energy consumption and pollution of red mud with high alkaline content existing in the alumina industry of China, whose most of bauxite resources with high silica content. Creative points of the study are as follows:
1. In oder to increase the grade of bauxite ore, pre-desiliconization of bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure was proposed in the first time. The dissolving characters and treatment effects of this system was basically studied. The result showed that pre-desiliconization of bauxite ore by this method was speediness, the time of leaching was about 5～20 min, far more quickly than any other method of pre-desiliconizition. The effect was good enough to meet the need of the requirement of the Bayer process on the grade of bauxite ore.
2. The effects of primary factors on this new process were investigated. The results shoued that the leaching rate of Al_2O_3 and SiO_2 were increased with the accretion of temperature, initial concentration of alkali and mass ratio of alkali to ore , and the affect of temperature on the leaching rate of Al_2O_3 was great than initial concentration of alkali did.
3. The kinetic characters of this process was studied, apparent activation energy of bauxite ore was 23.4kJ/mol, reaction order of desilicization for it was 0.9,the kinetic equation was obtained as
4. The basic research were also carried out about dissolving character and stability of Al_2O_3 and SiO_2 in sodium aluminate solution. The result was that sodium alumnate solution with SiO_2 in it was very steady, stable period of metastable was very long, it was uneasily for sodium aluminosilicate hydrate to separate out as crystal, and the concentration of SiO_2 was decreased slowly. However, through desiliconizition treatment , the leaching solution can be cyclic used, but the treatment would last a long time.
5. Based on the research results above, the principle flowsheet on the pre-desiliconizition of bauxite are by high-concentratied NaOH solution under atmospheric pressure was proposed, and the primary technical parameters of the pre-desiliconizition of bauxite by high-concentratied NaOH solution was optimized.
Pre-desiliconization of middle and low grade bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure has the advantagements of low ratio of solution to bauxite, low consumption of alkali, and without pressure in production process, may provide technical support for the expliotage of our typical middle and low grade bauxite ore.
1、为提高高硅铝土矿的品位，提出了常压下高浓碱液处理铝土矿的新方法。并对此体系的溶解特性及处理效果进行了应用基础研究。实验研究结果表明，采用此方法进行铝土矿预脱硅反应速度快，预脱硅时间在5～20min内，远远短于其它预脱硅方法。且脱硅效果理想，足以满足拜耳法生产氧化铝工艺对铝土矿品位的要求；
2、对常压下采用高浓度的NaOH溶液直接浸取铝土矿预脱硅的主要影响因素进行了研究。结果表明：SiO_2和Al_2O_3的溶出率随温度、初始碱液浓度和液固比的增大而增大，并且Al_2O_3的溶出率受温度影响比受NaOH初始浓度影响大；
3、研究了常压下高浓碱液浸取铝土矿的动力学特性，测定了铝土矿快速预脱硅反应的表观活化能为23．4kJ／mol，反应级数为0．9，得出脱硅动力学方程为：
4、对铝硅酸钠溶液中二氧化硅和氧化铝的溶解性及稳定性进行了基础性研究。结果表明，含氧化硅的铝酸钠溶液相当稳定，亚稳区间很宽。因此，饱和的铝硅酸钠很难结晶析出，液相中氧化硅浓度降低困难。但在延长处理时间的情况下，液相中二氧化硅浓度也可以达到较低的水平，从而能够实现碱液的循环利用；
5、根据上述基础性研究结果，提出了常压下高浓碱液浸取铝土矿预脱硅新工艺的适宜流程，优化了高浓碱液浸取铝土矿预脱硅新工艺的主要工艺参数。
常压下采用高浓氢氧化钠溶液处理中低品位铝土矿进行预脱硅，液固低，苛性碱使用量少，且常压操作，有望为开发利用我国典型的中低品位铝土矿提供技术支持。
A new process of pre-desiliconization of bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure was basically investigated and optimized, which was especially developed to resolve the key problems of great investment of equipments, high energy consumption and pollution of red mud with high alkaline content existing in the alumina industry of China, whose most of bauxite resources with high silica content. Creative points of the study are as follows:
1. In oder to increase the grade of bauxite ore, pre-desiliconization of bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure was proposed in the first time. The dissolving characters and treatment effects of this system was basically studied. The result showed that pre-desiliconization of bauxite ore by this method was speediness, the time of leaching was about 5～20 min, far more quickly than any other method of pre-desiliconizition. The effect was good enough to meet the need of the requirement of the Bayer process on the grade of bauxite ore.
2. The effects of primary factors on this new process were investigated. The results shoued that the leaching rate of Al_2O_3 and SiO_2 were increased with the accretion of temperature, initial concentration of alkali and mass ratio of alkali to ore , and the affect of temperature on the leaching rate of Al_2O_3 was great than initial concentration of alkali did.
3. The kinetic characters of this process was studied, apparent activation energy of bauxite ore was 23.4kJ/mol, reaction order of desilicization for it was 0.9,the kinetic equation was obtained as
4. The basic research were also carried out about dissolving character and stability of Al_2O_3 and SiO_2 in sodium aluminate solution. The result was that sodium alumnate solution with SiO_2 in it was very steady, stable period of metastable was very long, it was uneasily for sodium aluminosilicate hydrate to separate out as crystal, and the concentration of SiO_2 was decreased slowly. However, through desiliconizition treatment , the leaching solution can be cyclic used, but the treatment would last a long time.
5. Based on the research results above, the principle flowsheet on the pre-desiliconizition of bauxite are by high-concentratied NaOH solution under atmospheric pressure was proposed, and the primary technical parameters of the pre-desiliconizition of bauxite by high-concentratied NaOH solution was optimized.
Pre-desiliconization of middle and low grade bauxite ore through leaching by high-concentratied NaOH solution under atmospheric pressure has the advantagements of low ratio of solution to bauxite, low consumption of alkali, and without pressure in production process, may provide technical support for the expliotage of our typical middle and low grade bauxite ore.
引文
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[2] 张论和，何静华，张颖．我国氧化铝工业现状及发展对策[J]．轻金属，2006，2：3-7
[3] Laskou M, Margomenou- Leonidopoulou G, Balek V. Thermal Characterization of Bauxite Samples[J]. Journal of Thermal Analysis and Calorimetry,2006,84:141-145
[4] 杨重愚编．氧化铝生产工艺学[M]．北京：冶金工业出版社，1993
[5] 邱竹贤．泥土中的铝—科技腾飞的使者[M]．清华大学、暨南大学出版，2000，12：5-6
[6] 申慧．世界铝土矿及氧化铝的发展趋势[J]．有色金属工业．2003年第8期：24-28
[7] 姜涛，邱冠周，李光辉等．中低品位铝土矿选矿预脱硅的新进展[J]．矿冶工程，1999，2：3-6
[8] 罗建川．基于资源约束的氧化铝发展战略[J]．矿业研究与开发，2006，11：129-132
[9] 杨纪倩．我国铝土矿与氧化铝生产的现状与探讨[J]．世界有色金属，2006，(11)：17-19
[10] 于之春等．我国氧化铝生产技术及其发展趋势[J]．轻金属，1997，(4)：4-6
[11] 曾庆猛．对氧化铝工业可持续发展的再认识[J]．世界有色金属，2004，11：17-21
[12] Eric L, Bernard B, Odysseas K. Alumina Production from Diasporic Bauxites[J]. Light Metals, TheMinerals, Metals & Material Society, 1999, 55-61
[13] Seidel A, Zimmels Y. Mechanism and Kinetics of Alluminum and Iron Leaching from Coal Fly Ashby Sulfuric Acid[J]. Chem. Eng. Sci., 1998,53(22): 3835-3852
[14] BurmesterH. Aluminium-herausforderung and perspektiven[J].Erzmetall 2000, 53, 10, 629-636
[15] Capron T L. An Evaluation of Alternative Bauxites for Kaiser's Bayer Plant in GramercyLouisiana[J]. Light Metals, The Minerals, Metals & Materials Society, 1998, 11-14
[16] Reddy B R, Mishre S K,Banerjee G N. Kinrtics of Leaching of a Gibbsitic Bauxite withHydrochloric Acid[J]. Hydrometallurgy,1999, 51:131-138
[17] Fass R, Geva J, Shalita Z P, White M D, Fleming J C. Bioleaching for Recovery of Metal Valuesfrom Coal Fly Ash Using Thiobacillus Strains[J]. Israel Electric Corp. Isreal, Can. Pat. Appl., 1993
[18] 陈万坤，彭关才．一水硬铝石型铝土矿的强化熔出技术[M]．冶金工业出版社，1997,(21)
[19] (美)Errol．D．Shenke．王向丽译．二十世纪九十年中期世界铝土矿和氧化铝生产能力[A]．氧化 铝生产文集[C]．中国长城铝业公司科技部，1997：1-9
[20] 管永诗，张云．我国铝土矿资源及氧化铝工业的现状[J]．矿产保护与利用，1998，9：41-44
[21] 王桂琴，王继永．烧结法粗液与拜尔法溶出液进行合流脱硅的工艺研究[J]．世界有色金属， 2000，2：26-29
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