磷石膏制备硫酸铵反应动力学研究

以磷石膏和碳酸铵为原料制备硫酸铵 ,对反应过程的动力学进行了研究。按照收缩未反应芯模型导出了化学反应控制的模型方程 ,并确定了化学反应控制步骤的实验条件。在化学反应控制条件下进行实验研究 ,结果表明反应过程符合收缩未反应芯模型。测定了反应级数和反应活化能 ,建立了反应动力学方程。     

苯热解渗透炭抑制焦炭劣化反应动力学

进行苯热解渗透炭抑制焦炭劣化反应动力学实验,用未反应收缩核模型表征动力学实验数据,建立苯热解渗透炭抑制焦炭劣化反应动力学模型,确定模型参数.依所建动力学模型,计算出抑制焦炭劣化反应过程中的相对外扩散阻力ηg/Ση、相对内扩散阻力ηD/∑η和相对界面反应阻力ηC/∑η.研究结果表明:按Arrhenius方程得到苯热解渗透炭抑制焦炭劣化反应的活化能Ea=217.0 kJ/mol和有效扩散活化能ED=162.9 kJ/mol,均大于空白焦炭劣化反应的活化能Ea-142.0 kJ/mol和有效扩散活化能ED=96.30 kJ/mol;苯热解炭抑制焦炭劣化反应起始阶段主要受界面化学反应和外扩散影响,随着反应进行,劣化反应由内扩散、界面化学反应和外扩散同时影响;在较低温度下,焦炭劣化反应主要受界面化学反应控制,随反应温度升高,界面化学反应的相对阻力逐渐下降.     

热酸浸出黄钠铁矾渣工艺

以黄钠铁矾渣为原料,研究硫酸浸出过程的工艺条件,分析浸出过程的热力学和动力学机理.实验结果表明,在液固比为5∶1,搅拌速率为350 r/min条件下,浸出黄钠铁矾渣的最佳工艺条件为:硫酸质量浓度为225 g/L,反应温度为95 ℃,反应时间为2.5 h,该条件下多组实验的渣中Fe、Zn浸出率均大于96%.黄钠铁矾渣硫酸浸出过程在动力学上属于收缩核模型,受化学反应控制.     

石煤钠化焙烧料酸浸动力学

研究了石煤钠化焙烧料硫酸浸出过程中,浸出剂初始浓度、搅拌速度和浸出温度对浸出率的影响,并对浸出过程动力学进行了分析. 结果表明:浸出剂初始浓度和浸出温度对钒浸出率有显著影响,搅拌速度对钒浸出率影响不大;该浸出过程符合核收缩模型,与化学反应控制动力学方程式相吻合,浸出反应的表观活化能为50.88kJ·mol-1,浸出过程控制步骤为化学反应控制.     

合成三硝酸六尿素合铁的部分化工参数研究

在尿素铁生产中,铁与硝酸的反应和硝酸铁与尿素的反应,假设可简化为“收缩未反应芯模型颗粒大小不变”的情况进行讨论,以便于推导它们的宏观反应动力学方程,供生产过程参考.为此,本文用点热源比较瞬时法测定了硝酸铁与尿素铁溶液的导热系数,用电极法分别研究了硝酸铁和尿素铁的反应动力学,用腐蚀方法研究了硝酸与铁反应生成硝酸铁时铁颗粒大小与反应时间关系。     

锰锌铁氧体废料的浸出工艺

以锰锌铁氧体废磁芯粉料为原料,研究硫酸浸出过程的工艺条件,分析浸出过程的动力学机理.实验结果表明,在液固比为3:1,搅拌速度为300 r/min的条件下,锰锌铁氧体废磁芯粉料硫酸浸出过程的最佳工艺条件是:硫酸用量为其理论量的1.15倍,反应温度为95～100℃,反应时间为4.5 h.在此优化条件下,4次综合实验的Fe,Mn和Zn平均浸出率分别为98.83%,98.80%和98.82%;锰锌铁氧体废磁芯粉料的硫酸浸出过程在动力学上属收缩核模型,受化学反应的控制,反应活化能为85.6 kJ/mol.     

南方重稀土矿浸取动力学分析

探讨了浸取反应温度、浸取剂初始浓度，矿石粒度及搅拌强度对浸取速率的影响，并进行了浸取动力学分析。结果显示，其浸取过程可用收缩未反应芯模型表达，属内扩散控制，求出了表观活化能，导出了动力学方程，为高效，低耗合理地开采南方重稀土提供了科学的途径和理论依据。     

钢铁厂铁鳞硫酸的浸出过程

为制备高纯氧化铁,以钢铁厂铁鳞为原料,考察液固比、温度、时间和硫酸用量对铁浸出率的影响.研究确定硫酸浸出过程的工艺条件,分析浸出过程的动力学机理.确定硫酸浸出铁鳞的最佳工艺条件为:液固比3:1,温度100℃,时间6.0 h,硫酸用量为理论量的1.25倍.在此优化工艺条件下,铁鳞中Fe的平均浸出率为91.69%.动力学研究结果表明,铁鳞的硫酸浸出过程在动力学上属收缩核模型,即满足1/2(1-a1)-2/3-1/2=Kt,受化学反应的控制,反应活化能为70.40 kJ/mol.     

低含铟浸出渣中铟的氧压酸浸实验及动力学研究

采用氧压酸浸的方法浸出低含铟浸出渣中的铟,研究铟的氧压酸浸过程及动力学;研究搅拌速率、浸出温度、初始硫酸浓度、氧分压、物料粒度对铟浸出率的影响。研究结果表明:在浸出温度为220℃,物料粒度为75~80μm,硫酸浓度为1.53 mol/L,转速为650 r/min,氧分压为0.60 MPa时,铟、锌和铜的浸出率分别为99.5%,95.36%和95.94%;铟的浸出过程符合未反应收缩核模型,前期受化学反应控制,然后转为混合控制,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表观活化能分别为46.09 k J/mol和11.62 k J/mol。     

机械活化硫铁矿还原Fe 3+反应动力学

硫铁矿烧渣是生产硫酸时产生的固体废弃物.在50%的硫酸溶液中加入硫铁矿烧渣,于115 ℃反应4 h后过滤得到硫铁矿烧渣酸浸液.当酸浸液中Fe 3 和Fe 2 的浓度分别为2.016 mol/L和0.138 mol/L时,取酸浸液500 mL,加入40 g硫精矿,在90 ℃下反应240 min,Fe 3 被还原成Fe 2 的转化率只有26.30%;加入40 g机械活化硫精矿,在90 ℃下反应240 min,Fe 3 被还原成Fe 2 的转化率达到76.75%.实验结果表明:通过机械活化,硫铁矿反应活性大大提高;机械活化硫铁矿与硫铁矿烧渣酸浸液中Fe 3 反应符合收缩未反应芯模型,属化学控制;反应动力学方程为1-(1-x) 1/3=kt,其活化能E-0为35.12 kJ/mol.     

高硅硫铁矿烧渣浸出过程动力学机理

研究了高硅硫铁矿烧渣在硫酸浸出过程中的动力学机理,考察了液固比和温度对Fe浸出速率的影响.实验结果表明在液固比y<4.7时,y对浸出过程几乎没有影响;当y≥4.7时,增大γ,浸出率下降;硫酸浓度的反应级数为1.22;温度对Fe浸出速率的影响较大,提高温度有利于Fe的浸出;浸出1 h后浸出率能够很好地满足产物层扩散控制收缩核模型,即1+2(1一x)-3(1-x)2/3=kt;表观活化能为55.469 kJ/mol.此外,通过化学分析和EPMA分析,进一步证明了反应被产物层所控制.     

斑铜矿在酸性溶液中的浸出动力学行为

以斑铜矿为研究对象,在H₂SO₄酸性体系中,以NaS₂O₈为氧化剂,详细考察浸出时间、温度、矿物尺寸、液固比、H₂SO₄浓度和NaS₂O₈浓度对铜浸出率的影响.浸出行为表明,斑铜矿浸出动力学行为符合固体膜层的界面传质和扩散的混合控制,表观反应活化能为33.97 kJ/mol,浸出动力学方程为（ln(1-x)）/3-1+(1-x)^-1/3=k_mt.     

盐酸浸取高岭土中氧化铝的动力学研究

以安徽省淮北地区高岭土为原料,对盐酸浸取高岭土中氧化铝的反应动力学进行了研究。采用最小二乘法由微机进行数据处理,精确度高。文章建立了盐酸浸取高岭土中氧化铝的反应速率方程,得出了反应速率常数和温度的关系式,并在一定的条件下,对速率方程进行了验证。     

硝酸“催化”分解黄铁矿的动力学研究

本文在333～363K,硝酸根浓度0.1～0.5mol/L的条件下,实验研究了常氧压下硝酸“催化”分解黄铁矿的动力学。结果表明,黄铁矿分解后其中所含硫主要转化为硫酸根,浸出过程受化学反应控制,符合收缩未反应核模型,其表观活化能为39.87kJ/mol。根据实验结果推导出浸出速率的数学模型为: 1-(1-α)~(1/3)=6.30×10~2C_(NO_3)~(0.83)·C_H~(0.81)·r_0~(-1)·exp(-39.87×10~3/RT)t     

Sulfuric acid leaching kinetics of South African chromite

The sulfuric acid leaching kinetics of South African chromite was investigated. The negative influence of a solid product layer constituted of a silicon-rich phase and chromium-rich sulfate was eliminated by crushing the chromite and by selecting proper leaching conditions. The dimensionless change in specific surface area and the conversion rate of the chromite were observed to exhibit a proportional relationship. A modified shrinking particle model was developed to account for the change in reactive surface area, and the model was fitted to experimental data. The resulting model was observed to describe experimental findings very well. Kinetics analysis revealed that the leaching process is controlled by a chemical reaction under the employed experimental conditions and the activation energy of the reaction is 48 kJ·mol-1.     

Kinetic modeling of copper bioleaching from low-grade ore from the Shahrbabak Copper Complex

The copper recovery from low-grade copper sulfide ore was investigated using microbial leaching. Several parameters substantially affect the bioleaching of copper; among them, pulp density and nutrient media were selected for investigation. The optimum conditions for copper recovery were a pulp density of 5 g/mL, a mixed-mineral salt medium of Acidithiobacillus thiooxidans (70vol%) and Acidithiobacillus ferrooxidans (30vol%), and 10vol% of inoculum. Under these conditions, the maximum bioleaching capacity of the medium for copper recovery was determined to be approximately 99%. The effect of pulp density on the kinetics of the bioleaching process was surveyed using both da Silva's method and constrained multilinear regression analysis. The kinetics of copper dissolution followed the shrinking core model, and the process was diffusion controlled at a pulp density of 5 g/mL. Nevertheless, at higher pulp densities, the process was controlled by chemical reaction.     

低水工况氧化铁脱硫动力学的研究

采用收缩核模型,用热重法研究了无氧低水条件下常温氧化铁的脱硫动力学。研究结果表明,脱硫初末期控制转移,初期为表面反应控制,随着产物层不断加厚扩散阻力的增大,末期为扩散控制,并计算出初末期活化能。     

Isothermal reduction kinetics and mineral phase of chromium-bearing vanadium-titanium sinter reduced with CO gas at 873-1273 K

Reduction of chromium-bearing vanadium-titanium sinter (CVTS) was studied under simulated conditions of a blast furnace, and thermodynamics and kinetics were theoretically analyzed. Reduction kinetics of CVTS at different temperatures was evaluated using a shrinking unreacted core model. The microstructure, mineral phase, and variation of the sinter during reduction were observed by X-ray diffraction, scanning electron microscopy, and metallographic microscopy. Results indicate that porosity of CVTS increased with temperature. Meanwhile, the reduction degree of the sinter improved with the reduction rate. Reduction of the sinter was controlled by a chemical reaction at the initial stage and inner diffusion at the final stage. Activation energies measured 29.22-99.69 kJ/mol. Phase transformations in CVTS reduction are as follows:Fe₂O₃→Fe₃O₄→FeO→Fe; Fe₂TiO₅→Fe₂TiO₄→FeTiO₃; FeO·V₂O₃→V₂O₃; FeO·Cr₂O₃→Cr₂O₃.     

硫酸中香蕉皮还原低品位锰矿的浸出行为及动力学模型

Manganese was leached from a low-grade manganese ore (LGMO) using banana peel as the reductant in a dilute sulfuric acid medium. The effects of banana peel amount, H₂SO₄ concentration, reaction temperature, and time on Mn leaching from the complex LGMO were studied. A leaching efficiency of ~98% was achieved at a leaching time of 2 h, banana peel amount of 4 g, leaching temperature of 120°C, manganese ore amount of 5 g, and sulfuric acid concentration of 15vol%. The phase, microstructural, and chemical analyses of LGMO samples before and after the leaching process confirmed the successful leaching of manganese. Furthermore, the leaching process followed the shrinking core model and the leaching rate was controlled by a surface chemical reaction (1 ? (1 ? x)1/3 = kt) mechanism with an apparent activation energy of 40.19 kJ·mol?1.