【作者】 边雪；

【导师】 涂赣峰； 吴文远；

【作者基本信息】 东北大学 ， 有色金属冶金， 2008， 博士

【摘要】 包头混合型稀土精矿作为世界储量最丰富、产量最大的稀土资源,由于其成分复杂且含有难分解的独居石,因此处理困难。目前工业上应用的硫酸分解法和NaOH分解法都不同程度的存在成本和环境保护等问题。因此,合理开发、综合利用包头混合型稀土精矿对我国的经济建设具有很重要的意义。本论文以CaO-NaCl-CaCl2焙烧包头混合稀土精矿的产物为研究对象构思了一个全新的从包头稀土精矿中回收稀土,磷和氟的清洁生产工艺,并对流程的工艺条件、反应机理进行了研究。pH值滴定法、分光光度法以及红外光谱法证明了柠檬酸与混合稀土元素在溶液中通过柠檬酸的羧基和羟基配位存在REH2AOH2+、REHAOH+、REAOH、REAO-四种配合物形式,随着pH值的升高柠檬酸稀土的配位方式由单齿配位转变为桥连配位而后又转变为单齿配位。pH值电位滴定法测定柠檬酸稀土配合稳定常数分别为lgβ1=9.1,lgβ2=13.4,lgβ3=14.2,lgβ4=16.1。而在Ca2+、F-、PO43-多离子存在时,柠檬酸稀土溶液中稀土与柠檬酸仍能够形成配合物。溶液中含有与稀土等摩尔的Ca2+时条件配合稳定常数为lgβ1=6.9,lgβ2=10.8,lgβ3=12.9,lgβ4=13.1；含有与稀土等摩尔的F-时条件配合稳定常数为lgβ1=6.1,lgβ2=9.3,lgβ3=11.5,lgβ4=12.2；含有与稀土等摩尔的PO43-时条件配合稳定常数为lgβ1=6.5,lgβ2=9.7,lgβ3=12.3,lgβ4=12.7。研究了HCl-H3AOH酸洗包头稀土矿焙烧产物磷溶出以及酸洗液体碱化回收磷的工艺条件和动力学过程。结果表明,磷溶出率达到99.45%时的优化实验条件为：盐酸浓度0.5mol·L-1,柠檬酸浓度0.05mol·L-1,温度30℃,液固比10：1,时间25min,搅拌速度200 r·min-1；酸洗液经NaOH碱化调节pH值为9、控制温度为室温、时间为25min,磷的回收率达到99.51%,稀土的损失率仅为0.98%。沉淀理论计算及XRD分析确定碱化的沉淀物为羟基磷酸钙。酸洗及碱化的过程符合1-(1-α)1/3=Kt的动力学方程,反应速度随温度升高由化学反应速度控制(20～40℃)变为扩散和化学反应速度混合控制(40～50℃)直至扩散速度控制(50～60℃)。酸洗过程上述三段控制步骤的表观活化能分别为E1=42.35kJ·mol-1、E2=21.31kJ·mol-1、E3=1.18kJ·mol-1。碱化过程上述三段控制步骤的表观活化能分别为E1=43.3 kJ·mol-1、E2=27.4 kJ·mol-1、E3=3.03kJ·mol-1。研究了HCl-AlCl3浸出酸洗矿以溶解稀土氧化物和氟化钙的工艺条件和动力学过程。盐酸浓度3mol·L-1、Al3+浓度0.5mol·L-1、温度60℃、液固比10：1、时间60min、搅拌速度200 r·min-1的条件下,酸洗矿中RE2O3的浸出率为70.8%,CaF2的浸出率为55.8%。依上述条件经五级逆流浸出后酸洗矿中RE203的浸出率为99.62%,CaF2的浸出率达到98.56%。浸出的反应过程符合1-2/3α-(1-α)2/3=Kt的动力学方程,反应速度始终受扩散和化学反应速度混合控制。酸洗矿中稀土氧化物浸出和氟化钙浸出过程的表观活化能分别为ERE2O3=33.64 kJ·mol-1,ECaF2=23.68 kJ·mol-1。采用P204萃取回收浸出液中稀土,回收率达到98.6%。萃余液加NaOH回收氟铝酸钠,氟的回收率达到93.8%。对CaO-NaCl-CaCl2焙烧包头混合型稀土精矿产物的处理工序进行了全流程实验验证,结果表明：包头矿焙烧产物经酸洗、碱化、浸出等工序后,稀土直接回收率为98.28%,氟的直接回收率为84.30%,磷的直接回收率为96.36%,钙的直接回收率为41.17%。全流程中稀土主要损失方向为：稀土萃取余液中0.7%、浸出渣中0.36%、回收的氟铝酸钠中0.16%、回收氟铝酸钠余液中0.29%、其余0.21%为操作过程损失。焙烧矿中氟的主要损失方向为：碱化渣中8.16%、浸出渣中1.36%、回收氟铝酸钠的余液中5.69%、其余0.49%为操作过程损失。焙烧矿中磷的主要损失方向为：浸出渣中2.69%、碱化回收磷的滤液中0.13%、其余0.82%为操作过程损失。焙烧矿中钙的主要损失方向为：回收的稀土氧化物中1.39%,回收的氟铝酸钠中0.4%,回收稀土的余液中7.63%,回收氟铝酸钠的余液中48.9%,其余0.51%为操作过程损失。综上所述,论文所构思的新工艺既可以满足工业生产,又符合资源综合利用和环境保护的要求。更多还原

【Abstract】 The biggest storage and output of rare earth resource is Baotou mixed rare earth concentrate in world. This mineral is not easy to process due to its complex constituents and containing monazite which is difficult to be decomposed. Up till now the widely used methods of processing the Baotou mixed rare earth concentrate are to decompose it with sulfuric acid or NaOH, but these methods have the questions of cost and environmental protection. Therefore, exploitation and utilization of Baotou mixed rare earth concentrate with and reasonable and optimized method means a great deal to our country. In this thesis, the products from calcined Baotou mixed rare earth concentrate by CaO-NaCl-CaCl2 is investigated, a new clean technology of recovery RE, P and F from the products is designed, and the technology parameters and reactions mechanics of the new technology are studied.The results of pH value titration, spectrophotometric and FT-IR analysis testify that the mixed rare earth elements coordinate with citric acid through carboxyl and hydroxyl in water solution, and the coordination substances of REH2AOH2+, REHAOH+, REAOH and REAO-is coexistence in solution. With increasing pH value, the coordination modes change from monodentate ligands to bridiging ligands, and to monodentate ligands again. The coordination stability constants (β) of rare earth and citric acid are studied by pH potentiometric titration, and the results are lgβ1=9.1 for REH2AOH2+, lgβ2=13.4 for REHAOH+, lgβ3=14.2 for REAOH and lgβ4=16.1 for REAO- respectively. Rare earth still coordinates with citric acid when exists Ca2+, F- and PO43-. The conditional coordination stability constants are lgβ1=6.9,lgβ2=10.8,lgβ3=12.9,lgβ4=13.1 as existing Ca2+,lgβ1=6.1,lgβ2=9.3,lgβ3=11.5, lgβ4=12.2 as existing F-, and lgβ1=6.5,lgβ2=9.7,lgβ3=12.3,lgβ4=12.7 as existing PO43-.The technology parameters and the kinetic of the calcination products washed by HCl-H3AOH and basified by NaOH are studied. The results show that, when HCl concentration 0.5mol·L-1,citric acid concentration 0.05mol·L-1,liquid to solid 10:1,stirring speed 200 r·min-1.30℃and 25min, the phosphorus dissolution ratio is optimized to 99.45%. At the conditions of pH value 9, room temperature,25min, the recovery ratio of phosphorus from alkali acid washing solution is 99.51%,and the loss ratio of rare earth is only 0.98%. The hydroxyl calcium phosphate in processing of alkali precipitation is determined by theoretical calculation and XRD analyze. The process of acid washing and alkalization match to kinetic equation of 1-(1-α)1/3=Kt, and the reaction rate is controlled by chemical reaction control mode(20～40℃),mixed control mode(40-50℃) and diffusion control mode(50～60℃) respectively. The apparent activation energy of acid washing are E1=42.35kJ·mol-1for chemical reaction control mode, E2=21.31kJ·mol-1 for mixed control mode, E3=1.18 kJ·mol-1 for diffusion control mode respectively, and those of alkalization process are E1=43.3 kJ·mol-1, E2=27.4 kJ·mol-1,E3=3.03 kJ·mol-1 respectively.Furthermore, the technology parameters and the kinetic of acid washing minerals leaching by HCl-AlCl3 to dissolve RE2O3 and CaF2 are studied. The leaching ratio of RE2O3 and CaF2 is up to 70.8% and 55.8% respectively at the optimization parameters of HCl concentration 3 mol·L-1,Al3+ concentration 0.5 mol·L-1,liquid to solid 10:1,stirring speed 200 r·min-1,60℃with 60min. The leaching ratio of RE2O3 and CaF2 is to 99.62% and 98.56% respectively when quinternary contraflow leaching at the same parameters.The leaching process match to kinetic equation of 1-2/3α-(1-α)2/3=Kt, and the reaction rate is controlled by mixed control mode. The apparent activation energy of RE2O3 and CaF2 leaching process are ERE2O3=33.64 kJ·mol-1,ECaF2=23.68 kJ·mol-1.The studying results of kinetic show that the reaction rate increases with the increase of temperature, reactant concentration and stirring speed. Rare earth is recovered by P204 extraction from leaching solution, and the recovery ratio is 98.6%. The sodium fluoaluminate is recovered from faffinate adding NaOH, and the recovery ratio of fluorine is 93.8%.The treating procedures of calcined Baotou mixed rare earthconcentrate by CaO-NaCl-CaCl2 are verified by full-flow experiments. The results show that the direct recovery ratio of rare earth is 98.28%,fluorine is 84.3%,phosphorus is 96.36% and calcium is 41.17%. The loss of rare earth in full-flow is 0.7% in rare earth faffinate,0.36% in leaching slag,0.16% in filtrate of recovery sodium fluoaluminate and 0.21% when operation. The loss of fluorine is 8.16% in alkali precipitation,1.36% in leaching slag,5.69% in recovery filtrate of sodium fluoaluminate, and 0.49% when operation. The loss of phosphorus is 2.69% in leaching slag,0.13% in filtrate of recovery phosphorus, and 0.82% when operation. The loss of calcium is 1.39% in recovery rare earth oxide,0.4% in recovery sodium fluoaluminate, 7.63% in filtrate of recovery rare earth,48.9% in filtrate of recovery sodium fluoaluminate, and 0.51% when operation.The new clean technology of recovery RE, P and F from calcinations products satisfy the requirement of industry production, resource utilization, and environmental protection.更多还原