Accelerating leaching of copper ore with surfactant and the analysis of reaction kinetics

To solve the problem of low permeability and lower extraction rates of high-mud ores, a surfactant was added as a penetrant to the pregnant leaching solution during column leaching tests. On the basis of the theories of physical chemistry and seepage flow mechanics, the mechanism by which seepage is enhanced under the effects of the surfactant was analyzed. The results show that the action modes of the surfactant were divided into four aspects: changing the wettability of the ore, reducing the viscosity of the leaching solution, adsorbing onto the surface of ore, and enhancing the permeability effect. The findings of column leaching tests demonstrated that permeability was substantially improved by the surfactant. In the later period of leaching, the permeability coefficient was two times higher than that of the control group. Meanwhile, the ore extraction rate increased by approximately 10%. During the leaching process, the surface tension of the solution did not substantially change, and that of the solution with surfactant increased slightly. The kinetics analysis of ore column leaching illustrated that the leaching processes were controlled by both internal diffusion(principal factor) and chemical reaction.

Study on synergistic leaching of potassium and phosphorus from potassium feldspar and solid waste phosphogypsum via coupling reactions

To achieve the resource utilization of solid waste phosphogypsum(PG)and tackle the problem of utilizing potassium feldspar(PF),a coupled synergistic process between PG and PF is proposed in this paper.The study investigates the features of P and F in PG,and explores the decomposition of PF using hydrofluoric acid(HF)in the sulfuric acid system for K leaching and leaching of P and F in PG.The impact factors such as sulfuric acid concentration,reaction temperature,reaction time,material ratio(PG/PF),liquid–solid ratio,PF particle size,and PF calcination temperature on the leaching of P and K is systematically investigated in this paper.The results show that under optimal conditions,the leaching rate of K and P reach more than 93%and 96%,respectively.Kinetics study using shrinking core model(SCM)indicates two significant stages with internal diffusion predominantly controlling the leaching of K.The apparent activation energies of these two stages are 11.92 kJ·mol^(-1)and 11.55 kJ·mol^(-1),respectively.

Kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium

The kinetics of oxidative leaching of ocean polymetallic nodules in molten potassium hydroxide medium was investigated in terms of the gas-flow rate, stirring rate, reaction time, reaction temperature and partial pressure of oxygen on the ratio of manganese conversion in ocean polymetallic nodules. The category of the rate controlling step was determined. The process of the liquid-phase oxidation reaction can be described by surface chemical reaction-controlled non-reaction shrinking core model(SCM), the apparent activation energy was achieved and the rate equation was put forward. From the equation, it can be concluded that the reaction rate mainly depends on the reaction temperature and the partial pressure of oxygen.

Extraction and kinetic analysis of Pb and Sr from the leaching residue of zinc oxide ore

NH4HCO3 conversion followed by HCl leaching was performed and proven to be effective in extracting Pb and Sr from zinc extracted residual.The mechanism and operating conditions of NH4HCO3 conversion,including molar ratio of NH4HCO3 to zinc extracted residual,NH4HCO3 concentration,conversion temperature,conversion time,and stirring velocity,were discussed,and operating conditions were optimized by the orthogonal test.Experimental results indicate that NH4HCO3 conversion at temperatures ranging from 25 to 85°C follows the shrinking unreacted core model and is controlled by inner diffusion through the product layer.The extraction ratios of Pb and Sr under optimized conditions reached 85.15%and 87.08%,respectively.Moreover,the apparent activation energies of Pb and Sr were 13.85 and 13.67 kJ·mol^−1,respectively.

Oxygen pressure acid leaching of artificial sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation

The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.

Kinetics of indium dissolution from marmatite with high indium content in pressure acid leaching

The kinetics of oxygen pressure acid leaching marmatite with high indium content was studied. The effects of particle size, agitation rate, temperature, HSOconcentration, and oxygen partial pressure on leaching rate of indium were investigated. The results show that when the agitation rate is above 600 r-min, its influence on indium leaching rate is insignificant. It is determined that the leaching rates increase with the increase in sulfuric acid concentration, temperature, partial oxygen pressure, and the decrease in particle size. Moreover, the results demonstrate that the process of indium leaching is controlled by interface chemical reaction, with apparent activation energy of 65.7 k J-mol. The apparent reaction orders of sulfuric acid and oxygen partial pressure are determined to be 0.749 and 1.260, respectively. The leaching reaction process follows shrinking unreacted core model. And finally, the kinetics model equation is established for indium.

Leaching Kinetics of Calcium Vanadate by Na_2CO_3 Solution

Leaching kinetics of calcium vanadate by Na2CO3 solution was studied. Kinetic equation was established according to the variation of VO3-concentration with time during the leaching process. The influences of initial pH value and stirring speed on reaction rate constant were examined and the corresponding apparent activation energy was calculated. The results indicate that the leaching process is a 0.68 order reaction, and the reaction rate constant 8.64×10-6 mol/(L-s). It increases with the increase of pH value and stirring speed. And the dissolution rate of calcium vanadate also increases. The apparent activation energy is 38.98 kJ/mol, and temperature has great influence on the leaching rate of calcium vanadate.

Leaching of cuprite through NH_4OH in basic systems

Cuprite is a difficult oxide to leach under acidic conditions(for the maximum extraction of50%).In this research,the feasibility of leaching cuprite in an ammoniacal medium was studied.The working conditions addressed here were the liquid/solid ratio(120:1-400:1mL/g),stirring speed(0-950r/min),temperature(10-45℃)and NH4OH concentration(0.05-0.15mol/L).In addition,different ammoniacal reagents(NH4F and(NH4)2SO4)were analyzed.The experiments were performed in a2L reactor with a heating mantle and a condenser.The most important results were that the maximum leaching rate was obtained at pH10.5,0.10mol/L NH4OH,45℃,4h,850r/min and a liquid/solid ratio of400:1,reaching a copper extraction rate of82%.This result was related to the non-precipitation of copper in solution by the formation of copper tetra-amine (Cu(NH2)4^2+).The liquid/solid ratio and stirring speed were essential for increasing the cuprite leaching.The maximum leaching rate was achieved at higher temperatures;however,significant copper leaching rate occurred at temperatures near the freezing point of water(17.9%over4h).Increasing NH4OH concentration and decreasing particle size increased the cuprite leaching rate.The two ammoniacal reagents(NH4F and(NH4)2SO4)had low extraction rate of copper compared with NH4OH.The kinetic model representing cuprite leaching was a chemical reaction on the surface.The order of the reaction with respect to the NH4OH concentration was1.8,and it was inversely proportional to the radius of the ore particles.The calculated activation energy was44.36kJ/mol in the temperature range of10-45℃.

铅银渣混配铅精矿直接还原熔炼成渣特性及动力学解析

利用铅火法熔炼资源化消纳铅银渣等含铅固废已成为大势所趋。然而,由于原料结构明显差异导致常规高铅渣直接还原控制理论并不适用于混配铅银渣的反应过程。为此,在原料赋存状态及热力学分析基础上,结合还原实验对资源化消纳铅银渣的直接还原过程成渣特性及反应动力学规律进行了研究。结果表明,还原初期及还原后期(>30 min)均受界面反应控制,还原20~30 min内受外扩散控制,可通过增大反应界面及降低黏度来强化还原反应效率。随还原过程进行,渣中含铅相不断减少,锌黄长石相和铁锌尖晶石不断增加,硅酸盐结构由简单SiO_(4)^(4-)变为Si_(2)O_(7)^(4-),还原渣熔化温度及黏度均有所增加;控制终渣FeO/SiO_(2)=1.6,CaO/SiO_(2)=0.6,ZnO≤20 wt.%,可满足还原熔炼生产要求。

难选氧化锌矿氨浸动力学

兰坪氧化锌矿氨浸的动力学实验表明,氧化锌矿的氨浸动力学遵从不生成固体产物层的未反应核缩减模型,即符合1(1a)1/3=[MkCn/(brd0)]t方程. 通过研究氨水的浓度、温度以及矿石粒度对难选氧化锌矿浸出速率的影响,发现氧化锌矿氨浸反应为一级反应,得到反应的活化能为11.1 kJ/mol,为边界层扩散控制.

机械活化对磁黄铁矿浸出动力学的影响

利用X线衍射仪、比表面积测试仪、扫描电镜和粒径分析仪对未机械活化和经振动磨机械活化后的磁黄铁矿进行分析和表征。在FeCl3-HCl体系中对未机械活化和经机械活化后的磁黄铁矿的浸出动力学进行研究。研究结果表明:机械活化增加磁黄铁矿的微观结构缺陷和比表面积,粉末粒度减小,形成的团聚体非常明显;与未活化的磁黄铁矿相比较,经机械活化10,20和40 min后的磁黄铁矿化学反应活性提高,反应速度加快,表观活化能降低,其中表观活化能由未活化时的150 kJ/mol分别降至58,49和45 kJ/mol。

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 k J·mol–1和10.49 k J·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。

难选高硅氧化锌矿碱浸出动力学

研究了氢氧化钠处理难选高硅氧化锌矿的浸出动力学,考察了搅拌强度、浸出反应温度、氢氧化钠初始浓度对锌的浸出速率的影响。利用等浸出率法来确定其表观活化能和反应级数,得到表观活化能E=45.7 kJ/mol,属于化学反应控制;其反应级数K=1.4。实验结果表明,提高反应温度可显著提高锌的浸出率,而增大搅拌强度却对锌的浸出率基本无影响。

微生物催化大洋多金属结核和黄铁矿共同浸出及反应动力学模型

为了直观地表征大洋多金属矿微生物浸出过程中各因素的相互关系,进行了微生物催化MnO2-FeS2-H2SO4体系的好氧和厌氧浸出实验,利用DLVO理论建立厌氧条件下微生物催化浸出氧化锰矿物中有价金属的动力学模型——收缩核模型.微生物在厌氧条件下催化大洋多金属矿和黄铁矿的氧化还原反应,浸出锰的机理是细菌催化铁离子在二价和三价的循环转化;微生物吸附在矿物表面加速反应的进程,矿物颗粒在反应中不断缩小.进一步实验表明收缩核模型曲线与实验曲线拟合较好,验证了模型的可靠性.

MnO_2-FeS_2-H_2SO_4浸出体系下H^+和Fe^(3+)对MnO_2浸出的影响

在MnO2-FeS2-H2SO4浸出过程中,通过监测溶液中Mn2+浓度的变化,考察不同初始浓度下H+和Fe3+对MnO2浸出率和浸出速率的影响,并通过电化学研究对浸出过程中H+和Fe3+的作用进行分析。对Fe3+催化Mn O2-FeS2-H2SO4浸出过程进行电化学研究;同时对Fe3+催化MnO2-FeS2-H2SO4浸出过程进行了动力学分析。结果表明:硫酸浓度与MnO2浸出率和浸出速率存在密切关系;在硫酸浓度低于1 mol/L时,MnO2的浸出率随着硫酸浓度的上升而缓慢上升;硫酸浓度超过1 mol/L时,Mn O2的浸出率不再随硫酸浓度上升,甚至存在略微下降;同时发现反应初期MnO2的浸出速率与硫酸浓度呈正比关系,而在反应后期MnO2的浸出速率与硫酸浓度却呈反比关系。Fe3+在MnO2-FeS2-H2SO4浸出体系中具有重要作用,尤其是在反应初期有一定催化作用,Fe3+催化MnO2-FeS2-H2SO4浸出的过程完全符合产生固体反应物的固-液反应动力学,MnO2-FeS2-H2SO4浸出过程主要受FeS2表面反应及反应产物控制。

煤灰酸浸渣烧结反应试验

为了实现煤炭资源化分级利用,以东北某热电厂循环流化床锅炉灰渣硫酸酸浸提铝后的酸浸渣为原料,研究以碳酸钠为助剂烧结过程中可能发生的化学反应.基于热力学计算结果,研究酸浸渣-碳酸钠体系的焙烧配比、焙烧时间和焙烧温度对二氧化硅溶出率的影响.实验结果表明:当焙烧温度为1 153 K、焙烧时间为1.5h、酸浸渣∶碳酸钠质量比为2∶3时,酸浸渣中二氧化硅的溶出率达到86%.对酸浸渣热分解过程的动力学研究结果表明,该过程符合Crank-Ginstling-Braunshtein方程,由实验结果计算可得,表观活化能为156.46kJ/mol.

钛铁矿的机械活化及其浸出动力学

对攀枝花钛铁矿的机械活化及其浸出动力学进行了研究。结果表明:活化矿的浸出速率控制步骤随浸出的进行而发生变化,在浸出前期为液膜扩散和表面化学反应混合控制,而在浸出后期则为表面化学反应控制。这说明钛铁矿的机械活化过程是由颗粒外层向内层逐步推进的,存在一个未活化的芯层,而且在活性层中活性由表至里下降。对活化层进行了估算,其厚度约为40nm。

高铁闪锌矿加压浸出过程中Fe的动力学研究

进行了高铁闪锌矿加压浸出过程Fe的动力学研究。考察了温度、压力、始酸浓度、矿样粒度、溶液中Fe ^(2+)浓度对Fe浸出率的影响。结果表明,在试验条件下,浸出初期Fe的漫出速率受化学反应控制,遵循“未反应核减缩型”表面化学反应控制的动力学规律,浸出后期受固膜扩散控制,浸出中期由二者共同控制。

常压酸浸高冰镍的动力学研究

本文是关于常压酸浸高冰镍的动力学研究.实验考察了粒度、温度、硫酸浓度和氯离子浓度对镍浸出速率的影响.结果表明,在硫酸体系中选择性地浸出镍不仅在热力学上是可能的,而且反应速率快,完全能达到一次分离镍铜的目的.本文采用特殊的处理方法,将总镍浸出率R转换为Ni_3S_2中镍浸出率R^(?),从而导出实验条件下的动力学方程式.而浸出过程受通过产物层的固膜扩散控制.

輝锑矿浸出动力学的研究

本文针对目前湿法炼锑工艺过程研究的需要,对类似于辉锑矿浸出过程的液-固间歇式多相反应动力学模型进行了推导。用实际高价氯盐浸出辉锑矿的实验数据进行了验证。结果表明模型能较好地反映出实际过程的规律,并可以表示为:φ(R)=Kt。