【作者】 邵延海；

【导师】 冯其明；

【作者基本信息】 中南大学 ， 矿物加工工程， 2009， 博士

【摘要】 废铝基催化剂是一种以氧化铝为载体,富含钒、钼、镍、钴等有价金属的失效催化剂。对废铝基催化剂进行综合利用,不仅可避免有价金属的大量流失,又减轻了对环境的污染,具有重大的经济和环境意义。本文以一种废铝基催化剂为研究对象,在热力学分析基础上,开展了废催化剂中铝和其他金属的提取与分离、以及高品质特种氧化铝的制备研究,提出了由废铝基催化剂制备高纯超细氧化铝的综合利用新技术。论文的主要研究内容与创新点如下:1.废铝基催化剂中铝与镍、钴的分离热力学计算及分析结果表明,铝、钒、钼在温度大于962.2K后均能与碳酸钠发生反应,生成的钠盐可以离子形态转入碱性介质;镍、钴则不与碳酸钠发生反应,以氧化物或氢氧化物的固体形态存在于碱性介质中。这为废铝基催化剂钠化焙烧—浸出实现铝、钒、钼与镍、钴的分离提供了理论基础。在碳酸钠与（Al₂O₃+V₂O₅+MoO₃）的摩尔比为1.1,焙烧温度1000℃,焙烧时间30 min,浸出温度80℃,浸出时间30 min,液固比4:1,搅拌速度400 rpm的焙烧—浸出条件下,废铝基催化剂中铝、钒、钼的浸出率均在96%以上,镍、钴则完全富集在浸出渣中。2.碱性介质中铝与钒、钼的分离VO₄^3-、MoO₄^2-、Al（OH）₄^-与钙、钡反应体系的热力学分析结果表明,在铝、钒、钼共存的碱性介质中,钙将优先与VO₄^3-发生反应,使钒与铝、钼分离;钡随后与MoO₄^2-反应,使钼和铝分离。在此基础上,提出了分步沉淀法从碱性介质中分离铝与钒、钼的新方案:即在铝酸钠溶液中分步加入CaO和BaAl₂O₄,钒、钼的沉淀率可分别达到97%和99%,铝与钒、钼的分离效果好,并使铝酸钠溶液得到深度净化。3.高纯超细氧化铝的制备碳酸氢钠中和铝酸钠溶液可制备出多晶型的微米级氢氧化铝粉体,铝酸钠溶液碳分法则可制备出单一晶型的纳米级氢氧化铝粉体。铝酸钠溶液碳分过程中,反应温度是影响氢氧化铝粉体粒度的主要因素,降低反应温度可显著减小粉体粒度;反应终点pH对粉体粒度的影响次之;CO₂流量和分散剂PEG-1000用量的影响则不显著。氧化铝或氢氧化铝添加试剂焙烧—水洗后,都可使大部分的Na₂O得以脱除。氢氧化铝粉体添加NH₄F的脱钠效果最好,在适宜条件下,可得到纯度99.99%、平均粒径155nm的α相氧化铝粉体。4.废渣中钒和镍、钴的利用通过碳酸氢钠浸出、浸出液两段净化和铵盐沉钒处理,沉钒渣中92.5%的钒以五氧化二钒形式得到回收,制取的产品纯度达98.25%。镍钴渣硫酸浸出实验结果表明,在适宜条件下,镍和钴的浸出率分别达到97.8%和98.6%。对浸出液做进一步处理,可有望得到硫酸镍和草酸钴产品。5.由废铝基催化剂制备高纯超细氧化铝的综合利用技术在理论分析和实验研究基础上,提出了以制备高纯超细氧化铝为主要目的的废铝基催化剂综合利用工艺流程。该流程可实现废铝基催化剂的综合利用,得到氧化铝、钼酸钡、五氧化二钒和硫酸镍钴混合溶液四种产品,铝、钒、钼、镍、钴的回收率可分别达到83.73%、86.64%、91.8%、95.47%和96.53%。制备的氧化铝为纯度99.99%、平均粒径134nm的高纯超细α-Al₂O₃。更多还原

【Abstract】 Spent Al₂O₃-based catalyst is a kind of catalyst,using Al₂O₃as the carrier and vanadium,molybdenum,nickel and cobalt as active constitutent,but which can not be regenerated.Comprehensive utilization of spent catalyst shows great economic and environmental significance, not only for avoiding unacceptable drains of valuable metals,but also for alleviating environmental pollution.Aimed at a spent Al₂O₃-based catalyst,on the basis of thermodynamic analyses,the extraction and separation of aluminum and other metals in spent catalyst and the preparation of high purity ultrafineα-Al₂O₃ from purified sodium aluminate solution were studied.A comprehensive utilization technology for preparing high purity ultrafine alumina from spent Al₂O₃-based catalyst was proposed,and good results were achieved by pilot experiments.Main conclusions are obtained as follows:1.The separation of Al and Ni,Co in spent Al₂O₃-based catalystAccording to the thermodynamic calculation and analysis result, alumina,vanadium and molybdenum can react with sodium carbonate when the temperature is above 962.2K,and the sodium salts generated can be converted into respective ionic forms.Having no reaction with sodium carbonate at higher temperature,nickel and cobalt occur in solid forms of oxide or hydroxide in alkali medium.This provides theoretical basis for separation of aluminum,vanadium,molybdenum and nickel, cobalt from spent Al₂O₃-based catalyst.After roasting the mixture of Na₂CO₃ and spent catalyst with mol ratio of 1.1 at 1000℃for 30 min,the roast was leached at 80℃for 30 min with liquid to solid ratio 4 and stirring speed 400 rpm.Under this condition,the extractions of Al,V and Mo all could reach above 96%, while Ni and Co were totally enriched in leaching residue.2.The separation of Al and V,Mo in alkali mediumThe thermodynamic analyses for reaction systems of VO₄^3-,MoO₄^2- and Al（OH）₄^- with calcium and barium indicate that,in the alkali medium containing Al,V and Mo,calcium will be inclined to react with VO₄^3- firstly,thus V is separated from Al and Mo;barium will react with MoO₄^2- successively,and Mo is separated from Al.Based on this result,a new technique to separate Al and V,Mo in alkali medium by step precipitation is proposed.By adding CaO and BaAl₂O₄ successively in sodium aluminate solution,Al is considerably sperated from V and Mo. Under optimum condition,the precipitation rate of V and Mo reaches 97%and 99%,respectively,moreover,the sodium aluminate solution is highly purified.3.The preparation of high purity ultrafine alumina from purified sodium aluminate solutionThe neutralization process of sodium bicarbonate with sodium aluminate solution can prepare micron spherical Al（OH）₃ particle with multiple crystals;the carbonation decomposition of sodium aluminate solution can prepare well-distributed nano spherical Al（OH）₃ particle with single crystal.In the carbonation decomposition process,temperature is the dominating factor influencing the particle size of Al（OH）₃ powder,the effect of final pH on particle size is secondary,while CO₂ flow velocity and PEG-1000 dosage have no remarkable effect.By roasting alumina particle or aluminum hydroxide particle with reagent and water-washing roasted product,most Na₂O can be removed. The Na₂O removal effect of Al（OH）₃ particle roasting with NH₄F is the best,under proper condition,fineα-Al₂O₃ particle with purity near 99.99%and average diameter of 155nm can be obtained.4.Recovery of V and Ni,Co from residue V-bearing residue is treated by sodium bicarbonate leaching, purification of leach liquor and vanadium precipitation with ammonium salt,92.5%vanadium in V-bearing residue can be recycled in the form of V₂O₅ with purity of 98.25%.Sulfuric acid leaching Ni-Co residue indicates that,under suitable condition,97.8%nickel and 98.6%cobalt can be leached.Nickel sulfate and cobalt oxalate may be obtained with the further treatment of leach liquor.5.Research on the comprehensive utilization technology for preparing high purity ultrafine alumina from spent Al₂O₃-based catalyst Based on theoretical analyses and experimental research,a comprehensive utilization technology for preparing high purity ultrafine alumina from spent Al₂O₃-based catalyst was proposed and pilot experiment in terms of lkg spent catalyst was carried out.The results show that,by this technology,spent Al₂O₃-based catalyst can be comprehensively utilized,and four kinds of products including Al₂O₃, BaMoO₄,V₂O₅ and Ni-Co sulfate solution can be obtained.The integrated recovery of Al,V,Mo,Ni and Co is 83.73%,86.64%,91.8%, 95.47%and 96.53%,respectively.The preparedα-Al₂O₃ particle with purity of 99.99%and average diameter of 134nm has a higher added value.更多还原