金河磷矿在硫、磷混酸中的溶解动力学

参考二水物湿法磷酸的生产工艺条件,进行了金河磷矿在硫、磷混酸中的酸解动力学研究．考察了矿粉粒度、硫酸浓度及反应温度对酸解过程的影响;选用考虑了自阻化因素的德罗兹多夫方程描述酸解过程的动力学;利用修改后的Gioia酸解模型求得了磷矿酸解过程的有效扩散系数．     

高镁磷尾矿在硫酸中的溶解动力学

对高镁磷尾矿在硫酸中的溶解动力学进行了研究.考查了硫酸质量分数及反应温度对酸解过程的影响;选用考虑了自阻化因素的德罗兹多夫方程1/tln100/100-α-βα%/t=k描述酸解过程的动力学.研究结果表明:反应速率常数随温度的升高而增加,随硫酸质量分数的增加而减小.该反应属于扩散控制,反应活化能约为4～7kJ/mol.     

硫磷混酸分解磷矿反应动力学研究

采用四川清平磷矿和金河磷矿、贵州福泉和开阳磷矿为原料，试验研究了用硫磷混酸分解磷矿制取富过磷酸钙的反应动力学，分析了影响反应速度的主要因素，导出了用硫磷混酸分解磷矿的动力学方程式及判别过程的控制步骤。     

硫磷混酸分解清平磷矿第二阶段解特性研究

采用四川清平磷矿，研究了硫磷混酸分解磷矿第２阶段的酸解反应特性，实验结果表明扩散对过程影响严重，在此基础上提出了强化第２阶段反应过程的措施。     

磷矿浮选尾矿在硫磷混酸中的分解动力学研究

对硫磷混酸分解磷矿浮选尾矿的动力学进行了研究,结果表明,随着反应温度和P2O5浓度的提高,尾矿中MgO和P2O5的浸出率提高,在相同条件下,MgO浸出率高于P2O5浸出率,且由于磷酸的加入,生成了溶解度较大的Ca(H2PO4)2,降低了硫酸钙固体膜层的影响,有效改善了反应物和生成物通过固体膜层的扩散过程.硫磷混酸分解磷矿浮选尾矿的动力学,可用形成致密固体反应物膜的收缩未反应核模型来描述,动力学模型与实验结果拟合直线的相关系数均在0.97以上.通过.Arrhenius方程计算,MgO的表观活化能为9.95 kJ/mol,P2O5的为12.84 kJ/mol,说明硫磷混酸分解磷矿浮选尾矿容易进行,也说明酸解过程属于扩散控制过程.     

硫磷混酸分解清平磷矿第二阶段酸解特性研究

采用四川清平磷矿，研究了硫磷混酸分解磷矿第２阶段的酸解反应特性。实验结果表明扩散对过程影响严重，在此基础上提出了强化第２阶段反应过程的措施。     

超声波对磷矿酸解过程的强化

本文主要研究了超声波对硫酸分解磷矿过程的影响.讨论了超声的声强、时间、温度对磷矿酸解的影响.实验结果表明,磷矿分解率随着超声功率、反应时间和水浴温度的增加而提高.超声波对分解率的影响很大,特别是在酸解过程后期,可以提高16%左右.反应速率常数与温度的关系符合阿累尼乌斯方程.利用固体粒度不变的缩芯模型回归实验数据,得到宏观动力学模型.     

高镁磷尾矿在磷酸中的溶解动力学

对高镁磷尾矿在磷酸中的溶解动力学进行了研究,考查了磷酸中P2O5质量分数及反应温度对酸解过程的影响.选用考虑了自阻化因素的德罗兹多夫方程1/tln100/100-α-βα%/t=k来描述该过程的酸解动力学.研究结果表明:反应速率常数随温度的升高和磷酸中P2O5质量分数的增加而增加.该反应属于扩散控制,反应活化能约为29.2kJ/mol.     

硫磷混酸分解马边磷矿的反应过程动力学特性

采用四川马边磷矿,研究硫磷混酸分解磷矿的反应温度、磷矿粒度与分解率的关系。指出过程属扩散和化学反应的联合控制,并得到了过程传质系数及反应活化能（Ｅａ＝４２．８７ｋＪ／ｍｏｌ）。经归纳整理,提出混酸分解四川马边磷矿生产磷酸的动力学模型Ｋ＝１．０７４８×１０５ｅｘｐ（ｌ－４２．８７）／ＲＴ）,并对模型进行了检验。     

金河磷矿中磷、铁、铝和镁的酸解动力学研究

研究用大量磷酸分解磷矿的反应过程,并对金河磷矿中的磷、铁、铝和镁的酸解动力学过程进行了分析.研究表明,随着反应温度、磷酸浓度、颗粒细度的增加,磷矿分解速率均有增加,同时揭示了金河磷矿中铁、铝、镁杂质的分解规律.因铁杂质的赋存形态为FeS2,其最大分解率低于20%;而铝杂质分解率较高,其最大分解低于45%,并且它们的分解过程在一定的酸浓度范围内呈负温度效应.     

高镁磷尾矿中磷和镁在硫酸中的溶解动力学

对高镁磷尾矿中磷和镁在硫酸中的溶解动力学进行了研究,考察了固膜产物的物相形态变化及搅拌强度、反应温度和硫酸质量分数对溶解过程的影响. 结果表明,包含自阻化因素的德罗兹多夫方程能较好地描述P2O5和MgO的溶解过程,且二者溶解的阻缓系数均大于1.6,其表观活化能分别为14.881和11.908 kJ/mol,为固膜内扩散控制.     

低冰镍转炉渣中钴的氧压酸浸行为及其动力学

研究了转炉渣中钴氧压硫酸体系选择性浸出过程的行为及其动力学。通过改变搅拌速度、反应温度、硫酸浓度、氧分压、物料粒度以及反应时间等浸出条件,考察钴浸出率的变化及影响,获得转炉渣中钴的浸出动力学规律。结果表明,钴的浸出率随着温度、酸度、氧分压的增加而增加;硫酸质量浓度大于0.4 mol·L^-1会导致铁大量溶出;浸出过程符合未反应芯收缩核模型,前期受化学反应控制,然后转变为混合控制,后期受固体产物层扩散控制。化学反应控制和固体产物层扩散控制过程的活化能分别为43.19 kJ·mol^-1 和10.49 kJ·mol^-1。化学反应控制过程对硫酸浓度、氧分压及粒度的反应级数分别为0.79、0.85和 -0.95。     

硫酸分解钾长石的探讨

建立钾长石-硫酸常压水热反应体系,考查了反应温度、硫酸浓度、固液比以及反应时间对反应过程的影响。实验结果表明,硫酸能够分解钾长石,但常压下,硫酸分解钾长石溶出率只能在12%左右。在仅有硫酸和钾长石的常压体系下很难得到较高的钾溶出率。     

石煤灰渣酸浸提钒工艺中钒的浸出动力学

采用液-固多相反应的缩芯模型研究了石煤灰渣中V2O5的浸出动力学,考察了酸浸温度、硫酸浓度对V2O5浸出反应速率的影响. 结果表明,在实验温度范围内,V2O5的浸出过程为固膜扩散控制,浸出反应的表观活化能为29.96 kJ/mol. 当硫酸浓度小于6 mol/L时,浸出属化学反应控制过程;当硫酸浓度大于6 mol/L时,浸出过程为固膜扩散控制,其表观反应级数为1.199. 提高酸浸温度可提高V2O5的浸出率;在硫酸浓度小于6 mol/L时提高硫酸浓度,可提高V2O5的浸出率;而高于该值提高硫酸浓度对V2O5浸出率的提高无明显作用.     

A novel hydrometallurgy of molybdenite concentrate and its kinetics

BACKGROUND: In recent years, there has been an increasing focus on the hydrometallurgical processing of molybdenite, with the decline of high‐grade and easily handled molybdenum minerals. In this work, the technology of molybdenum extraction from molybdenite concentrate using sodium chloride electrolyte and its kinetics have been investigated. RESULTS: The results show that leaching temperature, sodium chlorate and sulfuric acid concentration significantly affected molybdenum extraction compared with other experimental parameters. With a NaClO₃ concentration of 320.39 g L^?1; sulfuric acid concentration of 73.3 g L^?1, a liquid‐solid ratio of 5:1, temperature 70 °C, agitation speed 500 rpm, the molybdenum dissolution rate achieved was 99.67% in 240 min. The activation energy of the dissolution reaction was 104.57 kJ mol^?1. CONCLUSION: The synthesized sodium chlorate electrolyte, an effective leaching agent, was used directly for the treatment of molybdenite concentrate. Removal of the crystallization and purification of sodium chlorate significantly reduced production costs. The results indicated that the inner diffusion and external diffusion control models were not suitable for this leaching reaction and the dissolution process was controlled by chemical reaction. Copyright © 2012 Society of Chemical Industry     

Nitration of nitrobenzene at high‐concentrations of sulfuric acid: Mass transfer and kinetic aspects

This article reports studies on mass transfer and kinetics of nitration of nitrobenzene at high concentrations of sulfuric acid in a batch reactor at different temperatures. The effects of concentration of sulfuric acid, speed of stirring, and temperature on mass transfer coefficient were investigated. The kinetics of nitration under homogenized conditions was studied at different sulfuric acid concentrations at these temperatures. The reaction rate constants were determined. The variation of rate constant with sulfuric acid concentration was explained by the M_c function. The activation energies of the reactions were determined from the Arrhenius plots. The regimes of the reactions were determined using the values of the mass transfer coefficients and the reaction rate constants. A model was developed for simultaneous mass transfer and chemical reaction in the aqueous phase. The yields of the three isomers of dinitrobenzene were determined, and the variation of isomer distribution with sulfuric acid concentration and temperature was analyzed. This work demonstrates that more than 90% conversion of nitrobenzene is possible at high‐sulfuric acid concentrations resulting in high yield of the product even at moderate temperatures and at low speeds of stirring. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Electro-dissolution of 30Nb–Ti alloys in methanolic sulfuric acid—Optimal conditions for electropolishing

The electro-dissolution behaviour of a (30 at.%) Niobium–Titanium (NbTi) alloy in non-aqueous methanolic sulfuric acid solution using the rotating disc electrode (RDE) was ascertained. The optimal condition for electropolishing and the mechanism were proposed. The influence of the rotation rate, process temperature and sulfuric acid concentration on the dissolution kinetics was investigated. The dissolution rate (limiting current) increases linearly with increase in rotation rate and follows a Levich behaviour confirming a mass transport controlled process. The temperature dependence in terms of Arrhenius plot renders an activation energy value of E_a = 16.1 kJ mol⁻¹ for the process. The dissolution rate shows a strong dependence on the sulfuric acid concentration (1 M, 3 M and 5 M). Higher sulfuric acid concentrations lead to decreased dissolution rates (limiting current). The dissolution process is mass transport controlled in all concentrations of sulfuric acid. From an electrochemical perspective, a 3 M sulfuric acid was chosen as optimum owing to better controllability of the material removal rate. The dissolving ions are the probable rate limiting species, indicating a compact salt-film mechanism. The average root mean square (RMS) roughness value for an electropolished surface was approximately 10 nm, which is significantly lower than a mechanically polished surface.     

包钢选矿厂尾矿中稀土与铁共提取

研究了包钢选矿厂尾矿经稀硫酸-稀盐酸溶解、溶解液在乙醇作用下结晶共提取稀土与铁的新工艺. 实验考察了稀硫酸溶解稀土尾矿时,溶解温度、硫酸浓度等对稀土和铁溶解率的影响. 最佳条件下稀硫酸溶解液中稀土溶解率低于8%,铁的溶解率大于94%. Fe3+经工业铁屑还原为Fe2+,在室温下用乙醇提取FeSO4,FeSO4纯度为98.21%,尾矿中铁回收率达89.51%. 稀盐酸不溶物中稀土氧化物(REO)品位为43.60%,稀土回收率达78.82%,新工艺实现了稀土和铁资源的提取分离.     

5-羟甲基糠醛在稀硫酸催化下的降解反应动力学

5-羟甲基糠醛脱羧生成乙酰丙酸是生物质资源出发制备乙酰丙酸过程中的关键步骤之一。为了研究低硫酸浓度下水解生物质制备乙酰丙酸工艺的可行性,系统地测定了在压力5 MPa、初始浓度1～9 mg·ml^-1、硫酸浓度0.05%～0.4%（质量分数）、温度150～190℃条件下,5-羟甲基糠醛在稀硫酸催化下的降解反应动力学数据,并以主反应生成乙酰丙酸、副反应生成腐黑质的平行反应动力学模型对数据进行了拟合,拟合结果表明,在实验范围内,主、副反应对5-羟甲基糠醛均为一级反应;主反应对H⁺浓度为1.16级,反应的活化能为78.5 kJ·mol^-1;副反应对H⁺浓度为0.722级,反应的活化能为98.0 kJ·mol^-1。研究结果表明,降低温度和提高硫酸浓度有利于提高生成乙酰丙酸的选择性。