钒酸钾钙化沉钒法制备钒酸钙

针对钾系亚熔盐法分解钒渣的中间产品钒酸钾,提出通过添加CaO实现钒酸钾中钾、钒分离,并同步实现钾再生循环的新方法,考察了各工艺参数对钙化沉钒的影响,得到钙化沉钒的最佳工艺条件. 结果表明,在KOH浓度140 g/L及CaO添加量为理论计算量的1.2倍、反应温度90℃、反应时间2 h的最佳工艺条件下,钒酸钾中钒转化率达95.9%以上,生成的钙化产物为Ca10V6O25,可直接用于钒铁冶炼,钾生成KOH返回用于分解钒渣.     

碱性介质多元体系中钒酸钠结晶分离

测定了NaOH-NaNO_3-NO_3VO_4-Na_2CrO_4-H_2O五元体系各盐在碱中的相平衡浓度,根据所得数据对该体系中的Na_3VO_4进行了冷却结晶分离.通过研究NaOH浓度、NaNO_3浓度、结晶终点温度、降温速度、搅拌速度、晶种对钒酸钠结晶分离的影响,得到的最优实验条件为:结晶液中NaOH浓度200~250g/L,NaN0_3浓度200g/L左右,搅拌转速200r/min,80~40℃自然降温,添加晶种量1%(ω),该条件下Na_3VO_4结晶率为61%,晶体纯度可达95%,且晶体颗粒人(147μm),沉降分离速度快(10min).     

由铬酸钾制备铬酸钠结晶分离过程研究

以铬酸钾中间体为原料,系统地研究了采用结晶分离等常规手段制备铬酸钠产品的清洁制备方法。应用等温法分别测定了KNO3在Na2CrO4水溶液中和Na2CrO4在KNO3水溶液中的相平衡数据,绘制了溶解度曲线,确定采用先冷却结晶后蒸发结晶的方法制备铬酸钠晶体产品。考察了冷却结晶终点温度和物料配比,分析了分步蒸发结晶产品,确定了结晶最佳操作条件:K2CrO4与NaNO3的质量比在1∶(0.9～1.2),冷却结晶的终点温度控制在4℃。提出铬酸钾通过结晶方式转化为铬酸钠的整体工艺流程,并进行了全流程循环实验。采用重结晶法对铬酸钠产品进行精制,获得高纯度的铬酸钠晶体,质量分数由81.4%提高到92.2%,且粒径较大,粒度均匀。     

铬酸钾-碳酸钾高效分离研究Ⅱ.结晶工艺实验研究

针对铬酸钾碳化法生产重铬酸钾母液利用过程,研究了K2CO3-K2CrO4-H2O体系蒸发-冷却结晶过程工艺条件。发现控制过饱和度的产生速率是过程控制的关键,少量铝、硅杂质的存在会在一定程度上抑制成核。铬酸钾的回收率可达95%以上,实现了碳酸钾与铬酸钾的高效分离。     

高纯偏钒酸钾制备工艺研究

以偏钒酸铵为原料,采用碱溶除杂、浓缩脱氨、溶析结晶的方法,制备的偏钒酸钾产品纯度大于99.5%。分析了制备过程的工艺原理,考察了pH、脱氨浓缩温度和钒浓度对偏钒酸钾成分的影响,探讨了溶析结晶的工艺条件。结果表明,影响偏钒酸钾质量的主要因素是碱溶除杂的pH和浓缩终点pH。制备过程的最佳工艺条件为：碱溶除杂pH为9~10、脱氨温度为95 ℃、浓缩终点pH为7.5~8.5、浓缩终点总钒质量浓度为180 g/L、溶析剂与溶液体积比为1∶1、结晶时间为30 min。滤液中残留的钒质量浓度低于3.0 g/L,钒收率达到98%以上。     

含钒钢渣中钒在KOH亚熔盐介质中溶出行为

对含钒钢渣中的钒在KOH亚熔盐介质中的溶出行为进行了研究,实验考察了反应温度、反应时间及碱渣质量比等因素对溶出过程的影响,并探讨了溶出机理. 结果表明,随反应温度、反应时间及碱渣比增加,钒的溶出率增加. KOH亚熔盐溶出含钒钢渣中钒的过程,是分解其中Ca2SiO4, Ca3SiO5, Ca2Fe2O5等固溶钒的物相,生成可溶性钒酸钾及不溶性的Ca(OH)2的过程. 并可通过控制浸出液中的KOH浓度避免钢渣中高CaO含量对钒沉淀的影响. 反应温度220~240℃、反应时间1 h、碱渣质量比为4时,钒浸出率高于90%. 与传统焙烧法相比,不仅显著降低了能耗,且提高了溶出效率.     

钾碱脱碳液中五价钒测定方法的商榷

通过试验证明钾碱脱碳液测定前不预分离试样中的低价硫化物，采用常规方法，直接在酸性体系中进行五价钒的测定，所得结果必然偏低或不能检出，无法指导脱碳工序的安全运行。     

钒酸钠钙化-碳化铵沉法清洁制备钒氧化物新工艺

钒酸钠的后续产品转化是钒渣亚熔盐法钒铬共提清洁生产工艺的关键环节,针对钒酸钠产品转化提出了钒酸钠钙化-碳化铵沉法清洁制备钒氧化物新工艺,系统研究了钒酸钠钙化、钒酸钙碳化铵化、偏钒酸铵冷却结晶等几个重要工序。结果表明：通过钙化-碳化铵化-偏钒酸铵结晶可实现钒酸钠产品清洁制备钒氧化物,钒回收率达96.99%,所得钒氧化物产品V₂O₅质量分数达98.53%以上,且从源头避免了高盐氨氮废水的产生,工艺清洁环保。     

铬酸钾-碳酸钾高效分离研究Ⅰ.相图分析与溶解度计算

铬酸钾-碳酸钾的高效分离是铬盐清洁工艺亚熔盐介质再生的重要环节.据K2CrO4-K2CO3-H2O体系溶解度分析,蒸发结晶是该分离过程控制的关键,对此进行了详细的相图分析.选用Pitzer模型的HW公式,以二元电解质溶液的Pitzer参数推算了100℃时K2CrO4-K2CO3-H2O体系相平衡情况,理论计算结果与实验结果吻合较好,最大相对误差为16.26%,平均相对误差为7.39%.     

铬盐清洁工艺亚熔盐介质脱除铝酸钾、碳酸钾研究Ⅱ结晶工艺

针对铬盐清洁工艺亚熔盐介质净化过程,研究了KOH-K2CO3-Al2O3-SiO2-H2O体系铝酸钾、碳酸钾混合盐的结晶行为.发现冷却时间、搅拌速率、冷却方式对结晶平均粒径具有重要影响,对晶种浓度也有一定影响.与控制冷却相比,线性冷却方式产生的结晶粒径稍小,除杂效果较好.在最佳工艺条件下亚熔盐介质中碳酸钾、铝酸钾的质量分数可分别降至4.67%、0.98%(以Al计),实现了亚熔盐介质的有效净化.     

铬酸钠与氯化钠的分离

研究了铬酸钠和氯化钠双饱和溶液在不同温度下的液相组成,提出了铬酸钠与氯化钠分离的新方法,并根据相图,确定了分离操作的工艺条件和循环流程。实验结果表明,重结晶法对除去铬酸钠中的氯化钠是有效可行的。     

铬酸钾碳酸化回收钾碱的初步研究

探讨了铬酸钾碳酸化制备钾碱的反应过程中铬酸钾初始浓度、二氧化碳分压和反应温度对碳酸化结果的影响. 结果表明,在铬酸钾浓度为40%、二氧化碳分压0.6 Mpa、反应终点温度18℃的条件下, 所得碳酸氢钾的浓度可达225 g/L以上. 并推导了其反应机理和动力学方程.     

Influence of K2CrO4 Doping on the Structural,Optical and Dielectric Properties of Polyvinyl Alcohol/K2CrO4 Composite Films

Polyvinyl alcohol/potassium chromate (K₂CrO₄) composite films were prepared by solution casting technique using distilled water as a solvent, and were further investigated using Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction, thermogravimetric analysis, optical microscopy, scanning electron microscopy, and dielectric measurements. Microscopic studies reveal that K₂CrO₄ was homogenously mixed with polyvinyl alcohol matrix due to interfacial interaction between polyvinyl alcohol and K₂CrO₄. The composite films showed very high dielectric constant and relatively low dielectric loss. Hence, such composite materials with improved dielectric properties could be useful for fabrication of electrical charge storage device.     

铬酸钾-甲醇/乙醇-水体系溶解度研究

通过对铬酸钾-甲醇／乙醇-水三元体系在25，40，60℃下铬酸钾溶解度的研究和比较，及铬酸钾-甲醇／乙醇在25℃时铬酸钾的溶解度的测定，为采用溶析结晶方法从含有铬酸钾的水溶液体系中分离铬酸钾提供了基础数据，为铬酸盐的清洁分离提供了新的思路。     

KMnO4在碱性介质中与Na2SO3反应实验的探讨

从高锰酸钾在碱性介质中与亚硫酸钠反应实验入手,探讨了该反应的影响因素（试剂加入顺序、试剂的浓度,以及试剂加入量等）;对按照现行教材进行该实验,不能得到稳定的锰酸钾溶液情况,结合理论和具体实验加以分析和讨论,并在保证实验效果、节约药品的前提下提出了改进措施。     

Phase Separation and Crystallization in Glasses of the Na2O–K2O–Nb2O5–SiO2 System

The structure of initial glasses in the Na₂O–K₂O–Nb₂O₅–SiO₂ system with an Nb₂O₅ content ranging from 5 to 39 mol % and their structural transformations in the course of isothermal treatments at different temperatures are investigated using small-angle X-ray scattering (SAXS) and X-ray powder diffraction. It is demonstrated that, in glasses containing 15 mol % Nb₂O₅ and more, the metastable phase separation is the primary process responsible for the formation of a microinhomogeneous structure. With further heat treatment of these glasses, NaNbO₃ crystals precipitate in regions with a high Nb₂O₅ content. In this case, each region has a heterogeneous structure and consists of NaNbO₃ microcrystals surrounded by layers of the high-silica matrix. These layers hinder transfer processes and, consequently, recrystallization, which ensures the stability of the heterogeneous structure and, correspondingly, constant sizes of microcrystals at temperatures up to 750–800°C. The intensity of light scattering is determined primarily by the sizes of regions formed upon phase separation. A decrease in their size with an increase in the niobium oxide content leads to a decrease in the light scattering loss and an increase in the transparency of heat-treated samples. The interference effects associated with the heterogeneous structure of high-niobate phase regions also favor an increase in the transparency of the prepared materials.     

On the Phase Separation and Crystallization of Glasses in the MgO–Al2O3–SiO2–TiO2 System

The changes in the structure and phase composition of glasses in the MgO–Al₂O₃–SiO₂–TiO₂ system (at different TiO₂ contents and ratios MgO : Al₂O₃) upon their heat treatment in the temperature range 700–960°C are investigated by small-angle X-ray scattering (SAXS) technique and X-ray powder diffraction analysis. The influence of gallium oxide additives on the phase separation and crystallization is analyzed. It is demonstrated that the heat treatment results in the phase separation, which occurs through the spinodal decomposition mechanism. A regular structure formed upon phase separation is retained after the completion of crystallization in inhomogeneity regions. The interference effects due to the regularity in the distribution of nanocrystals in the vitreous matrix bring about a decrease in the light scattering intensity and provide transparency of glass-ceramic materials.