制备碳酸锂结晶的工艺优化

主要针对含锂卤水通过氯化锂与碳酸钠反应结晶制备高纯度碳酸锂过程中存在的结晶问题做了实验研究。通过考察反应结晶初始浓度、反应温度、进料速率、晶种用量、搅拌速率、进料浓度以及添加剂等对碳酸锂产品的平均粒度及晶体形貌的影响,优化了反应结晶制备碳酸锂的工艺参数。研究表明：在不同优化参数的作用下,通过调控碳酸锂的反应结晶过程,可改变碳酸锂晶体的形貌、粒度及固液分离效果。     

响应曲面法优化碳酸锂反应结晶工艺

碳酸锂是制备各种锂化合物的基础锂盐,碳酸锂的制备是锂产业链当中的承前启后的关键技术。以察尔汗盐湖老卤为原料,采用响应曲面法中的central composite design（CCD）设计实验,分别考察了温度、碳酸钠加料速度、碳酸钠浓度和锂离子浓度4个因素及交互作用对反应结晶工艺中碳酸锂的收率和粒度的影响,并分别建立了响应值与影响因素之间的回归方程。响应预测最佳值为：碳酸锂收率93.68%、粒径（d₅₀）16.73 μm;相应的实验值分别为94.01%和16.91 μm。预测值与实验值接近,误差较小,说明响应曲面法建立的预测碳酸锂反应结晶的模型可靠,在最佳工艺条件下分析所制得的产品,用ICP-AES分析纯度为99.52%,用XRD分析基本无杂峰,说明反应结晶生成Li₂CO₃晶体,其主要晶面为（-1 1 0）、（-2 2 0）和（0 0 2）。     

氯化锂与碳酸钠反应结晶制备碳酸锂的研究

中国主要以矿石为原料生产碳酸锂（Li2CO3）,而从锂含量丰富的盐湖卤水中直接生产优质的碳酸锂产品具有广阔的前景。对氯化锂（LiCl）和碳酸钠（Na2CO3）反应结晶生产碳酸锂的过程做了研究,考察了碳酸钠加入量、搅拌速度、温度、氯化锂浓度、添加剂及加料方式对反应结晶过程的影响。得到了较佳的工艺条件：以反加料的方式进行反应,碳酸钠加入量为理论加入量的110%,搅拌速度为400 r/min,反应温度为80 ℃,c（LiCl）=3.2 mol/L。结果表明,搅拌转速对产品产率的影响不明显,碳酸钠加入量、温度和氯化锂浓度对产品的产率有影响,其中温度和氯化锂浓度的影响显著。加料方式和加入聚丙烯酸（PAA）作为添加剂可以得到不同的产品形貌;搅拌速度、反应温度、LiCl浓度以及PAA作为添加剂对Li2CO3纯度均有一定程度的影响。     

反应结晶制备碳酸锂的粒度及形貌控制

碳酸锂的粒度及形貌决定其性能和应用。通过考察反应结晶温度、进料速率、晶种用量和搅拌速率对碳酸锂产品平均粒径的影响以及添加剂的用量对产品形貌的影响,提供了一种经过优化的制备碳酸锂的反应结晶工艺。通过正交实验确定了反应结晶制备碳酸锂的最佳实验条件：200 mL质量浓度为90 g/L的氯化锂溶液一次性加入反应结晶器内,质量浓度为260 g/L的碳酸钠溶液的加料速率为0.5 mL/min,晶种用量为2%（占碳酸锂理论产量的分数）,搅拌速率为400 r/min,反应温度为80 ℃,添加剂六偏磷酸钠用量为2%（占碳酸锂理论产量的分数）。在此条件下制得的碳酸锂为平均粒径为132 μm、变异系数为51.53%的密实球形产品。研究表明,反应温度对晶体粒度的影响最大,添加剂对晶体的粒度和形貌起到调控作用。     

碳酸锂气液固三相反应结晶过程研究

碳酸锂的气液固三相反应结晶过程包含碳酸锂碳化反应和碳酸氢锂溶液的热析分解两个过程。首先对于碳化过程,考察了碳酸锂碳化转化率和反应速率的影响因素;建立并求解构建碳化微观机理模型,进而确定了碳酸锂碳化过程为气体传质控制。对于热析分解过程,研究了碳酸锂晶体产品的粒度分布、晶体形貌和聚结程度等与反应物浓度、温度、搅拌、晶种以及外场等因素的关系,尤其是在超声结晶条件下能够获得形貌完整且不聚结的碳酸锂棒状晶体。最后,揭示了碳酸锂的结垢机理,并基于实验验证提出了光滑表面、介稳区控制和晶种添加等方案可有效抑制结垢。     

田口实验设计法优化TPGS单酯与双酯的柱层析分离工艺

采用田口设计法对TPGS单酯与双酯的柱层析分离工艺进行优化。采用Minitab 15软件设计正交试验方案,并分析不同因素不同水平下的信噪比值。实验结果表明TPGS单酯与双酯回收率的最优方案分别为上样量1.5 g、上样浓度0.4 g/mL、流速4 mL/min、柱温30℃和上样量1.5 g、上样浓度0.3 mg/mL、流速3 mL/min、柱温30℃。田口方法预测的TPGS单酯与双酯回收率最优结果分别为95.19%和96.12%,验证实验结果分别为94.89±0.56%和95.08±0.31%。结果表明所优化方案具有较好稳定性,为工业分离提供了参考。     

碳酸锂结晶动力学研究

为了更好地指导生产,采用无蒸发恒容间歇反应器对Li2CO3自LiHCO3溶液中的结晶动力学进行了研究。实验结果表明,温度的升高及质量浓度的增大能显著提高结晶速率,低的系统压力及搅拌有利于结晶反应的进行。根据实验数据拟合得到了该结晶过程的宏观动力学方程。晶体的生长机制表明,扩散控制机制是Li2CO3自LiHCO3溶液中生长的主导机制。     

反应结晶过程研究（Ⅰ）——激光法研究结晶热力学与反应动力学

采用激光测量装置研究了普鲁卡因青霉素在不同温度,不同浓度,不同ｐＨ值的氯化钠水溶液中的溶解与超溶解特性,以及其生成反应的反应动力学,为系统研究普鲁卡因青霉素反应结晶过程提供了一定的热力学和反应动力学基础。     

碳化法制备电池级碳酸锂工艺优化研究

碳化法因具有反应高效、工艺简单等特点,已成为电池级碳酸锂生产的主流工艺。但是,在以盐湖锂精矿为原料采用碳化法制备电池级碳酸锂的过程中,还存在碳化过程二氧化碳利用率低、碳化液杂质去除效果不好以及锂的收率低等问题。以盐湖锂精矿为原料,从碳化、净化、热解3个主要环节进行了工艺优化实验,即由常压碳化改为加压碳化、采用化学净化和离子交换树脂吸附相结合的方法去除碳化液中的杂质、由常规热解改为加压热解,可将碳化过程二氧化碳利用率提高到87.4%、净化过程钙镁去除率分别提高到97.92%和96.09% 、全流程锂的直收率提高到82.27%。     

反应结晶制备硼氢化钾

针对Schlesinger法生产碱金属硼氢化物工艺存在的结晶母液循环成本较高和副产物累积导致产品质量降低等问题,设计开发了反应结晶制备硼氢化钾这一过程,用于处理生产过程中的结晶母液,以提高硼氢化物收率,同时生产出具备一定经济效益的硼氢化钾。采用了容量分析中的碘量法、光学显微镜分析技术和马尔文粒度分析仪、X射线粉末衍射仪等设备,考察了反应结晶过程各项因素对最终产品性质的影响。结果表明：控制反应物质的量之比为1.05~1.10,反应温度为50℃,降温速度10℃·h^-1,养晶温度0℃,可以得到符合行业标准的硼氢化钾产品。     

Optimization of preparation conditions of poly(vinylidene fluoride)/graphene oxide microfiltration membranes by the Taguchi experimental design

Poly(vinylidene fluoride) (PVDF)/graphene oxide (GO) microfiltration membranes were prepared via phase inversion process. The Taguchi experiments were designed to optimize the preparation conditions of composite membranes. PVDF content, solution type, GO content, and poly-(N-vinyl-2-pyrrolidone) (PVP) content were chosen as important effecting parameters. Membrane filtration resistance was optimized by calculating the signal-to-noise (S/N) ratio of the parameters. The group of PVDF = 12 wt.%, solution type = N, N-dimethylacetamide (DMAC), GO = 3 wt.%, and PVP = 5 wt.% was the optimal combination, and solution type was the most effective factor. Scanning electron microscope (SEM) images showed that all membranes had thicker finger-like substructures. To further investigate the influence of GO on antifouling and mechanical properties, the pure PVDF and PVDF/GO composite membranes (3.0 wt.%) were prepared according to the optimum conditions. The PVDF/GO composite membranes presented better antifouling performances due to the improvement of membrane hydrophilicity. The tensile strength and Young's modulus reached values of 10.33 and 148.47 MPa, which corresponded to a 55.11% and 67.14% increase, respectively.     

Separation of copper ions by electrodialysis using Taguchi experimental design

With the aid of atomic absorption, a systematical and analytical evaluation method called Taguchi's quality engineering has been applied for the separation of copper ions from a solution using a laboratory electrodialysis set-up to evaluate the optimal experimental conditions and hence to achieve the highest removal percentage and the best robustness of the quantitation from the least number ofexperimental runs. Fourparameters at three levels were studied: concentration (100, 500, 1000 ppm), temperature (25, 40, 60°C), flow rate (0.07, 0.7, 1.2 mL/s) and voltage (10, 20, 30 V). Two types of different membranes with different ion-exchange capacities were used. The optimal levels thus determined for the four influential factors were: concentration 1000 ppm, temperature 60°C, flow rate 0.07 mL/s and voltage 30 V. It has also been found that using a membrane pair with higher ion-exchange capacity improves performance. The highest removal percentage was found to be 94.94% and 97.33% for the two types of membranes.     

应用田口方法设计苯酐精制的最佳控制参数

采用田口品质设计方法来达到苯酐在精制过程中杂质参数的控制,找出顺酐、苯甲酸、苯酞、蒽醌及重组分的最佳控制指标,得到苯酐精制产品.首先设置可控因子水平表,由方差分析确定最佳试验条件;其次以信噪比作为稳健性指标,采用望小设计方案,就模拟参数的稳健性进行了望小分析;最后以试验对分析结果进行了验证,确认此设计方法在本工程领域中创新应用的可行性.将此设计方法得到的参数控制结果应用于化工生产实践,给出了精馏塔塔顶的最佳工艺控制指标,使苯酐的优等品率显著提高,对优化苯酐生产工艺具有直接指导意义.     

Optimization of experimental conditions based on Taguchi robust design for the preparation of nano-sized TiO2 particles by solution combustion method

This investigation was aimed at preparing nanocrystalline TiO₂ powder by solution combustion method, and searching the optimum preparing conditions by employing Taguchi robust design method. Taguchi robust design method with L₁₈ orthogonal array was implemented to optimize experimental conditions for preparing nano-sized titania particles. Titanium IV n-butoxide was hydrolyzed to obtain titany1 hydroxide [TiO(OH)₂], and titanyl nitrate [TiO(NO₃)₂] was obtained by reaction of TiO(OH)₂ with nitric acid. Finally, the aqueous solution containing titanyl nitrate [TiO(NO₃)₂] and a fuel, glycine, were mixed and combusted to obtain the nano-sized titania. The optimum conditions obtained by this method are as follows (based on 1 mol of TiO₂ per batch): concentration of HPC, 0.053 mg cm⁻³; mole ratio of Ti:H₂O:IPA, 1:4:10; hydrolysis time, one hr; the amounts of HNO₃ and glycine are 10 ml and 0.5 g, respectively; nitrated temperature, 298 K and nitrated time, 2 h. TiO₂ nanocrystalline (∼15 nm) with high BET surface area (350 m² g⁻¹) and narrow band gap energy (2.7 eV) were thus obtained.     

Synthesis and characterization of magnesium hydroxide by batch reaction crystallization

Magnesium hydroxide with high purity and uniform particle size distribution was synthesized by the direct precipitation method using MgCl₂ and NaOH as reactive materials and NaCl as additive to improve the crystallization behavior of the product. The particle size distribution, crystal phase, morphology, and surface area of magnesium hydroxide were characterized by Malvern laser particle size analyzer, X-ray diffraction (XRD), scanning electron microscope (SEM) and Branauer-Emmett-Teller (BET) method, respectively. The purity of products was analyzed by the chemical method. The effects of synthesis conditions on the particle size distribution and water content (filtration cake) of magnesium hydroxide were investigated. The results indicated that feeding mode and rate, and reaction temperature had important effects on water content and the particle size distribution of the product, and sodium chloride improved the crystallization behavior of magnesium hydroxide. The ball-like magnesium hydroxides with the particle size distribution of 6.0–30.0 μm and purity higher than 99.0% were obtained. This simple and mild synthesis method was promising to be scaled up for the industrial production of magnesium hydroxide.     

碳化法制备高纯碳酸锂

以工业级碳酸锂为原料,采用碳化法进行提纯,对碳化温度、碳化时间、碳化压力等重要影响因素进行了实验研究及分析,并确定了最佳反应条件。最佳工艺参数：碳化压力为6×105～6.5×105 Pa,碳化时间为2～3 h,碳化温度为30～40 ℃,树脂牌号为D110,母液流出速度为120～140 g/h,分解搅拌速度为30 r/s以上,此工艺条件下制得的碳酸锂纯度为99.991%。     

基于正交试验和MPI二次开发技术多目标优化注射工艺参数

工艺条件是影响注射成型制品质量的重要因素,采用CAF模拟软件进行注射成型的工艺优化不但能降低成本,提高效率,而且能提高注射制品的质量。本文通过MPI二次开发技术开发出注射成型工艺方案优选分析器,采用正交试验方法为用户提供多目标值下的最优工艺参数组合,进一步提高了工艺优化的效率,也为用户提供了实用方便的工艺优化工具。