石煤提钒碱浸过程动力学研究

研究了石煤空白焙烧料NaOH溶液浸出过程中液固比、NaOH溶液初始浓度、反应搅拌速率、矿石粒径、温度对浸出速率的影响,确定了石煤提钒碱浸过程动力学方程式,计算了反应的表观活化能.结果表明:液固比、反应搅拌速率对浸出速率的影响不大,NaOH溶液初始浓度、矿石粒径、浸出温度对浸出速率的影响显著;V2O5的浸出动力学适用于收缩未反应芯模型,浸出反应服从化学反应控制过程;根据Arrhenius公式,使用曲线拟合法,近似求得该反应表观活化能约为58.5 kJ·mol-1,进一步表明该反应属于化学反应控制.     

硫酸镁浸出离子型稀土矿动力学研究

为提高硫酸镁作为浸矿剂浸出稀土时的稀土浸出效率,对其浸出动力学进行研究.采用搅拌浸出的方式进行动力学实验,明晰浸出过程动力学控制步骤,并结合Arrhenius方程求取反应的表观活化能及动力学方程,此外,考察了浸出温度、硫酸镁浓度、搅拌速度以及矿石粒径对稀土浸出过程的影响.结果 表明:硫酸镁浸出离子型稀土矿动力学符合未反...     

从云母型含钒石煤中酸浸钒、铝的动力学

采用"核收缩"模型研究了湖北某地含钒石煤硫酸浸出过程中钒、铝的浸出动力学。结果表明,钒的浸出动力学过程与钒的转价有密切关系:在25~45℃条件下,浸出初期,钒的浸出以五价钒及颗粒表面四价钒为主,受化学反应控制,表观反应活化能为36kJ/mol;浸出后期,反应界面向颗粒内部推移,钒的浸出转化为内扩散控制,以四价钒为主,表观反应活化能升高为64kJ/mol。在55~95℃条件下,三价钒亦被活化,钒的浸出过程受内扩散控制,表观反应活化能最高,为91kJ/mol。铝由于赋存状态单一,始终受晶格束缚,其浸出动力学过程受内扩散控制,表观反应活化能较高,为68kJ/mol。钒、铝浸出均为二级反应,对硫酸浓度依赖性较大。     

蛇纹石酸浸提镍过程动力学研究

研究了在蛇纹石硫酸浸出镍过程中,浸出剂初始浓度、搅拌速度、矿石粒径和浸出温度对镍浸出率的影响,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、浸出温度和矿石粒径对镍浸出率有显著影响,搅拌速度对镍浸出率影响不大.硫酸浸镍过程符合关系式1-(1-η)1/3=kt,反应频率因子为190.56,表观活化能为48.79 kJ/mol,浸出过程受化学反应控制.     

从复杂多金属硫化矿中提取铋的浸出动力学研究

研究了采用盐酸和氯化铁从低品位复杂多金属硫化矿中提取铋的浸出动力学。分析了反应时间、粒度及盐酸浓度对铋浸出率的影响,依据试验数据计算出浸出反应的表观活化能为31.32 kJ/mol。研究表明,收缩核模型可以描述盐酸浓度超过1 mol/L时的浸出过程,无论在产物层或边界流体膜,浸出率由一个扩散过程(抛物线浸出)控制,得出了相关的动力学方程。     

用草酸从赤泥中浸出钪、镧试验研究

研究了用草酸从赤泥中浸出钪和镧,考察了草酸用量、反应时间、温度、液固体积质量比对浸出的影响,分析了浸出动力学。结果表明：在赤泥质量1 g、草酸用量4.5 g,反应时间120 min、温度90℃、液固体积质量比12/1条件下,钪、镧平均浸出率分别为66.68%和78.23%;钪浸出过程符合多相液-固反应模型,反应受扩散控制,表观活化能为25.68 kJ/mol;镧浸出过程符合未反应收缩核模型,受化学反应控制,表观活化能为55.10 kJ/mol。     

磷矿中稀土浸出的动力学研究

研究了硝酸浸出磷矿中稀土的动力学,考察了温度、浓度、粒度对稀土浸出率的影响。结果表明,提高温度和浓度、减小粒度均能提高稀土浸出率。浸出过程符合未反应收缩核模型,受界面化学反应控制,表观活化能为70.6 kJ/mol,表观反应级数为0.83级。     

磷酸法中稀土溶出的动力学模型研究

利用磷酸浸出伴生稀土磷矿,研究了温度、时间、酸度、粒度与稀土浸出动力学的关系。结果表明,升高温度、延长反应时间、增大酸度、减小初始粒度均有利于稀土的浸出。界面化学反应控制为稀土浸出的控制步骤,表观反应级数0.993,表观活化能44.6kJ/mol,稀土浸出过程近似为基元反应。按反应核收缩核模型通过统计分析建立了关联温度、浓度、粒度三因素的稀土浸出数学模型。     

含碳酸盐脉石氧化铜矿的酸浸动力学

针对碳酸盐脉石对氧化铜矿酸浸动力学的影响进行探讨,研究了温度、酸度、矿石粒径、液固质量比、振荡速度等因素对含碳酸盐脉石氧化铜矿浸出的影响.结果表明,高温、高酸度、高液固质量比、小粒径和高振荡速度利于矿石的浸出,但碳酸盐脉石使得酸耗增加.考虑浸出成本确定合理的浸出条件为温度303 K、酸度35 g·L^-1、矿石粒径0.074~0.125 mm、液固质量比3∶1以及振荡速度180 r·min^-1,浸出180 min后铜浸出率达53.6%.对浸出前后矿石表面形貌进行分析.结果显示碳酸盐脉石与酸反应后在矿石表面形成CaSO₄·2H₂O沉淀,覆盖在颗粒表面,限制了矿石颗粒孔裂隙的发育.基于收缩未反应核模型对浸出动力学进行分析,发现碳酸盐脉石反应生成的沉淀阻碍了浸出反应,固体产物层扩散为浸出反应的控制步骤,反应的表观活化能为8.65 kJ·mol^-1.     

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50.88 kJ·mol^-1,浸出过程控制步骤为化学反应控制.     

Investigation of Leaching Kinetics of Copper from Malachite Ore in Ammonium Nitrate Solutions

The production of metallic copper from low-grade copper ores is generally carried out by hydrometallurgical methods. Leaching is the first prerequisite of any hydrometallurgical process. Solutions containing ammonia may allow for selective leaching of the copper from the ore. In this study, the leaching kinetics of malachite, which is an oxidized copper ore, in ammonium nitrate solutions was examined. The effects of some experimental parameters on the leaching process were investigated, and a kinetic model to represent the effects of these parameters on the leaching rate was developed. It was determined that the leaching rate increased with increasing solution concentration, temperature, and agitation speed, as well as decreasing particle size. It was found that the leaching reaction followed the mixed kinetic controlled model, which includes two different leaching processes including the surface chemical reaction (303?K to 323?K [30?°C to 50?°C]) and diffusion through a porous product layer (323?K to 343?K [50?°C to 70?°C]). The activation energies of these sequential steps were determined to be 95.10 and 29.50?kJ/mol, respectively.     

Treatment of a Nigerian covellite ore. Part I: Dissolution kinetics study by ammonia solution

In the present work, the leaching kinetics of covellite ore in ammonia solution was studied and the following variables, the solution concentration, reaction temperature and particle size were considered. A kinetics model representing the effects of these variables on the leaching rate was developed and it was ascertained that the leaching rate increases with increasing solution concentration, reaction temperature and decreasing particle size. At optimal conditions, 75.1% of covellite ore was reacted within 120 min and the leaching reaction was diffusion controlled by surface chemical mechanism. The calculated activation energy of 56.98 kJ/mol supported the proposed dissolution process.     

微波活化铜精矿加压浸出动力学

铜精矿经微波活化后,在初始硫酸浓度1.23 mol/L,液固比（mL/g）30/1,氧分压0.6 MPa,搅拌转速度500 r/min条件下,在408～453 K范围内研究了加压浸出动力学,并与微波活化前浸出动力学进行比较.结果表明,微波活化前后,铜精矿铜、锌浸出行为规律基本一致.在408～438 K范围内,铜精矿微波活化前后,铜浸出速率未见明显变化,而当温度升高至453 K后,铜浸出速率较微波活化前略有增大.当温度低于423 K时,锌浸出速率较微波活化前略有增大;当温度高于438 K时,锌浸出过程反而略有放缓.微波活化铜精矿铜、锌浸出反应的表观活化能分别为56.33、49.77 kJ/mol,铜、锌浸出过程均遵循界面化学反应控制的收缩核模型.与活化前相比,铜精矿经微波活化后铜、锌浸出过程得以促进.     

Kinetics of copper dissolution during pressure oxidative leaching of lead-containing copper matte

The kinetics of pressure oxidative leaching of lead-containing copper matte with sulfuric acid was investigated. The effects of particle size, leaching temperature, oxygen partial pressure and sulfuric acid concentration on the kinetics and mechanism of copper extraction were studied. It was found that the reaction kinetic model follows the shrinking core model of chemical reaction control and the apparent activation energy was determined as 39.1 kJ/mol. The order of the reaction with respect to total pressure was found to be 0.64. The kinetic equations for the effect of particle size, leaching temperature, total pressure and sulfuric acid concentration were obtained and a mathematical model of copper extraction from lead-containing copper matte was developed as:

This equation estimates the extraction of copper with very good agreement (r = 0.99) between the experimental and calculated values.     

Reaction Kinetics of magnesite ore in dilute ethanoic acid

The leaching of naturally occurring magnesite in dilute ethanoic acid is achieved to optimize the reaction conditions affecting the reaction kinetics. In the current study effect of various reaction parameters (The particle size of ore, concentration of leaching agent, the reaction temperature and rate of stirring) on the dissolution of magnesium carbonate ore with aqueous solutions of acetic acid is probed. It is inferred that the rate of leaching reaction of magnesium carbonate ore in the aqueous solutions of acetic acid rises with a rise in temperature of reaction medium, acetic acid solution strength and decreases with the increase in particle size of the magnesite ore samples. The analysis of kinetic data done by the application of graphical and statistical approaches reveals that the leaching kinetics of magnesite ore in dilute solutions of acetic acid follows a surface chemically controlled mechanism. The calculated value of energy of activation for the dissolution reaction of magnesium carbonate in acetic acid is 46.39 kJ mol^–1.     

Dissolution kinetics of argentian plumbojarosite from old tailings of sulfatizing roasting pyrites by Hcl-CaCl2 leaching

The nature of argentian plumbojarosite contained in old tailings of sulfatizing roasting pyrites has been studied. HCl-CaCl₂ leaching has been investigated over a temperature range of 60 to 90 °C with 0.175 to 1 M HC1 and 0 to 200 g/1 CaCl₂ as a means of selective leaching. The analysis of experimental data, independent of the stirring speed and cinder particle size, shows that the chemical reaction on the surface of the plumbojarosite crystals is the rate limiting step. This is supported by an activation energy of 96 kJ/mole. A first-order dependence with respect to the hydrochloric acid activity was found with or without the addition of calcium chloride. A micrograin model was applied to explain the leaching behavior, which is in satisfactory agreement with the experimental data.     

Kinetics of sulphuric acid leaching of a zinc silicate calcine

Recent developments of acid leaching and solvent extraction of zinc silicate ores have produced renewed commercial interest. However, the leaching kinetics of these concentrates has received little attention. This work, therefore, addresses the leaching of a zinc silicate concentrate in sulphuric acid. The effects of particle size (0.038–0.075mm), temperature (30–50°C) and initial acid concentration (0.2–1.0mol/L) were studied. The results show that decreasing the particle size while increasing the temperature and acid concentration increase the leaching rate. As leaching occurs, there is a progressive dissolution of willemite while the quartz and iron-containing phases remain inert. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control successfully described the zinc leaching kinetics. The model enabled the determination of an activation energy of 51.9 ± 2.8kJ/mol and a reaction order of 0.64 ± 0.12 with respect to sulphuric acid, which are likely to be a consequence of the parallel nature of diffusion and chemical reaction in porous solids.