电镀污泥中铬的无害化处理及动力学分析

以某表面处理工业园电镀废水处理污泥为研究对象,以铬浸出率为指标,通过对重金属的浸出,分步回收达到无害化、资源化的目的.将污泥干燥、研磨,在不同浓度硫酸溶液中浸出,控制浸出时间、浸出温度和搅拌速率;浸出完成后抽滤使浸出液与残渣分离.采用正交试验法,确定对铬浸出效果影响因素的顺序为:硫酸浓度>搅拌速度>浸出时间>固液比.通过单因素优化试验,结果显示:当浸出温度为25 ℃、固液比为1∶15、浸出时间为20 min、搅拌速率为800 r/min、硫酸体积分数为30%时,铬的浸出率最高.最后用黄钠铁矾法除铁,用焦亚硫酸钠还原六价铬,用氢氧化钠分步沉淀铬、镍重金属,锌则继续留在溶液中.电镀污泥的浸铬实验的浸出动力学研究结果表明硫酸作为浸出剂的反应级数为1,反应的速率常数为:k=0.053 2e-4.52/RT.     

Leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system

The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69μm, holding at 80℃ for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2：1, and the ratio （g/mL） of solid to liquid being 1：10.     

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.     

Extraction of nickel from molybdenum leaching residue of metalliferous black shale by segregation roasting and acid leaching

The recovery of nickel from molybdenum leach residue by the process of segregation roasting-sulfuric acid leaching-solvent extraction was investigated. The residue was characterized by microscopic investigations, using X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD) techniques and the residue after segregation roasting was characterized by chemical phase analysis method. A series of experiments were conducted to examine the mass ratio of activated carbon (AC) to the residue, segregation roasting time and temperature, sulfuric acid concentration, liquid-to-solid ratio, leaching time, leaching temperature, addition amount of 30% H₂O₂, stirring speed (a constant) on the leaching efficiency of nickel. A maximum nickel leaching efficiency of 90.5% is achieved with the mass ratio of AC to the residue of 1:2.5, segregation roasting time of 2 h, segregation roasting temperature of 850 °C, sulfuric acid concentration of 4.5 mol/L, liquid-to-solid ratio of 6:1, leaching time of 5 h, leaching temperature of 80 °C, addition of 30% H₂O₂ of 0.6 mL for 1 g dry residue. Under these optimized conditions, the average leaching efficiency of nickel is 89.3%. The nickel extraction efficiency in the examined conditions is about 99.6%, and the nickel stripping efficiency in the examined conditions is about 99.2%.     

Dissolution kinetics of malachite in ammonia/ammonium sulphate solution

The dissolution kinetics of malachite was investigated in ammonia/ammonium sulphate solution. The effects of ammonia and ammonium sulphate concentration, pH, leaching time, reaction temperature, and particle size were determined. The results show that the optimum leaching conditions for malachite ore with a copper extraction more than 96.8% are ammonia/ammonium concentration 3.0 mol/L NH₄OH + 1.5 mol/L (NH₄)₂SO₄, liquid-to-solid ratio 25:1 mL/g, leaching time 120 min, stirring speed 500 r/min, reaction temperature 25 °C and particle size finer than 0.045 mm. The dissolution process of malachite with an activation energy of 26.75 kJ/mol is controlled by the interface transfer and diffusion across the product layer. A semi-empirical rate equation is obtained to describe the leaching process and the reaction orders with respect to concentration of ammonia and ammonium sulphate are 2.983 0 and 0.941 1, respectively.     

电镀污泥中铜的浸出工艺及其动力学

以硫酸为浸出剂,对某表面处理工业园电镀废水处理污泥中的铜做了浸出试验研究.将污泥干燥、研磨,X射线衍射和X射线能谱仪分析表明污泥中含铜19.03%.采用单因素优化试验探讨了固液比、反应时间、浸出温度、硫酸质量分数、搅拌速度对铜浸出率的影响.结果表明:当硫酸质量分数为20%,固液比为1∶10,搅拌速率为700r/min时,在20℃下反应40min,铜的浸出率可达97%以上;根据未反应核收缩模型,对硫酸浸铜过程的动力学机理进行了研究,结果表明:硫酸浸铜过程的控制步骤为固体膜扩散控制,其反应级数为0.828 2,浸出活化能为11.809kJ/mol.研究为含铜电镀污泥安全处置提供理论依据.     

Leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate as oxidant

The leaching kinetics of molybdenum from Ni-Mo ore in sulfuric acid solution with sodium peroxodisulfate was studied.The effects including leaching temperature, reaction time, particle size, stirring speed, and concentrations of sulfuric acid and sodium peroxodisulfate were investigated. The leaching process of molybdenum from Ni-Mo ore is controlled by the chemical reaction through the solid layer across the unreacted shrinking core. The apparent activation energy of the leaching of molybdenum is calculated to be 41.0 k J/mol and the leaching kinetics equation of molybdenum from Ni-Mo ore is expressed as1-(1-a)1/3=3405.7exp[-41030.0/(RT)]t.     

Study on hydrometallurgical process and kinetics of manganese extraction from low-grade manganese carbonate ores

In order to utilize low-grade manganese ore resources effectively, a hydrometallurgical process was developed for manganese extraction in dilute sulfuric acid medium, and the kinetics of leaching manganese was also investigated. At room temperature, manganese from low-grade manganese carbonate ores was extracted by sulfuric acid leaching without reductants. During the extracting process, single-factor analysis method was used to evaluate the effects of grinding fineness, sulfuric acid concentration, liquid-to-solid ratio, agitation rate and leaching time on the leaching efficiencies of Mn and Fe. The optimal leaching conditions are determined as coarse particles of below 2 mm size (without ball-milling), sulfuric acid concentration of 0.86 mol/L, liquid-to-solid ratio of 5:1, agitation rate of 150 r/min and leaching for 180 min at room temperature. Under the optimal conditions, the leaching efficiencies of Mn and Fe are 96.21% and 13.35%, respectively. In addition, through the experiments at different temperatures, it is found that the leaching process follows the shrinking core model under the conditions of changing acid concentration and intermittent reaction device. Moreover, the apparent activations of effective diffusion and chemical reaction in the kinetic model are calculated to be 18.83 and 27.15 kJ/mol, respectively.     

Leaching kinetics of acid-soluble Cr（VI） from chromite ore processing residue with hydrofluoric acid

Leaching kinetics of acid-soluble Cr(VI) in chromite ore processing residue (COPR) using hydrofluoric (HF) acid solution as a leaching agent was investigated for potential remediation of COPR with industrial waste water containing HF. The results show that HF can effectively destabilize the Cr(VI)-bearing minerals, resulting in the mobilization of Cr(VI) from COPR into the leachate. Particle size significantly influences the leaching of acid-soluble Cr(VI) from COPR, followed by leaching time, whereas the effects of HF concentration and leaching temperature are slight and the influence of stirring rate is negligible. The leaching process of acid-soluble Cr(VI) from COPR is controlled by the diffusion through the product layer. The apparent activation energy is 8.696 kJ/mol and the reaction orders with respect to HF concentration and particle size is 0.493 8 and −2.013 3, respectively.     

二氧化硫液相浸取低品位软锰矿的动力学

研究了液相中二氧化硫对低品位软锰矿的浸出行为。考察了液相搅拌转速、温度、二氧化硫浓度及pH对锰浸出率的影响,研究了软锰矿粒径及表面元素相对含量随锰浸出率的变化,并对其浸出的动力学模型进行了分析。实验结果表明,搅拌转速为400r/min时可消除外扩散对锰浸出率的影响。锰浸出率随温度、二氧化硫浓度的升高而增大,随pH的增大而减小。当锰浸出率为80%时,软锰矿粒径减小约20%,表面锰含量减小73%,硅元素含量增大18%。动力学研究结果表明,软锰矿的浸出过程为扩散-化学反应混合控制过程,反应的活化能为36.85KJ/mol,二氧化硫浓度、氢离子反应级数分别为1.5595和0.5884。     

New technique of comprehensive utilization of spent Al2O3 -based catalyst

A new technology was developed to recover multiple valuable elements from the spent Al2O3-based catalyst by X-ray phase analysis and exploratory experiments. The experimental results show that in the condition of roasting temperature of 750 ℃ and roasting time of 30 min, molar ratio of Na2O to Al2O3 of 1.2, the leaching rates of alumina, vanadium and molybdenum in the spent catalyst are 97.2%, 95.8% and 98.9%, respectively. Vanadium and molybdenum in sodium aluminate solution can be recovered by precipitators A and B, and the precipitation rates of vanadium and molybdenum are 94. 8% and 92. 6%. Al（OH）3 was prepared from sodium aluminate solution in the carbonation decomposition process, and the purity of Al2O3 is 99. 9% after calcination, the recovery of alumina reaches 90. 6% in the whole process; the Ni-Co concentrate was leached by sulfuric acid, a nickel recovery of 98. 2% and cobalt recovery over 98.5% can be obtained under the experimental condition of 30% H2SO4, 80 ℃, reaction time 4 h, mass ratio of liquid to solid 8, stirring rate 800 r/min.     

一种改性钛渣钛组分的分离方法

研究了碱浸出过程中的影响因素,考察了浸出温度,NaOH溶液的浓度,以及物料粒度和液固比等因素对于浸出效果和回收率的影响.得到了碱浸阶段适宜的工艺条件为：溶液中NaOH的质量分数为15%、浸出温度100℃、浸出时间6 h、液固比20 mL/g、钛渣粒度小于38μm,搅拌速度500 r/min.采用三段浸出的方法获得了品位为91.42%,回收率为78.47%的人造金红石产品.     

Simulation of solute transportation within porous particles during the bioleaching process

A mathematical model,accounting for the sulfuric acid and ferric ions diffusion and the copper sulfide mineral leaching process, was developed for an ore particle by considering its porous structure.It was simulated with the simulation tool COMSOL Multiphysics.The simulation results show that the highest acid and ferric concentrations near the particle surface are apparent,while the concentrations in the central particle increase slightly as the less-porous ore core with low permeability prevents the oxi...     

Leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system

The leaching kinetics of low grade zinc oxide ore in NH3-NH4Cl-H2O system was studied. The effects of ore particle size,reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined.The leaching kinetics of low-grade zinc oxide ore in NH3-NH4Cl-H2O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69μm, holding at 80℃ for 60min, sum ammonia concentration of 7.5mol/L, the molar ratio of ammonium to ammonia being 2:1, and the ratio (g/mL) of solid to liquid being 1:10.     

Nickel extraction from low grade laterite by agitation leaching at atmospheric pressure

This research work deals with the extraction of nickel from a low grade nickel laterite ore, taken from a deposit located in southwestern of Iran, through agitation leaching at atmospheric pressure. The assaying and mineralogical studies carried out on the nickel laterite sample, showed the 0.88% Ni, and principally consisted of oxide and silicate crystalline phases i.e. dolomite, quartz, magnetite, and goethite. Among numerous factors affecting such process, four major parameters i.e. temperature, agitator speed (r/min), leaching agents and their concentration were considered in a two-level full factorial experimental design. The agitation leach tests showed that the ore could be leached at atmospheric pressure with sulfuric acid while citric acid was almost unpromising. Analysis of variance (ANOVA) using DX7 software was employed to identify effective parameters. Sulfuric acid concentration and temperature were the most effective parameters on Ni extraction. Furthermore, the factorial models for experiment responses were developed. The results showed 83% Ni extraction after 4 h leaching, under optimized conditions i.e. temperature at 95 °C, acid concentration at 5 N and agitator speed at 1000 r/min. This study revealed that factorial experimental design can be implemented to identify effective parameters on the agitation leaching process of nickel laterite.     

废旧印刷线路板两步浸出有价金属

为回收废旧印刷线路板中的有价金属,采用两步浸出的方法对其进行处理.先用双氧水-硫酸浸出贱金属,再用王水浸出贱金属浸出渣中的金.10 g废旧印刷线路板贱金属最佳浸出条件为双氧水20 mL,固液比1:5,硫酸浓度5 mol/L,反应温度60℃,反应时间90 min,原料溶损率达90.0%;金最佳浸出条件为反应温度40℃,反应时间30 min,浸出率达97.5%,研究证明两步浸出法能有效处理废旧印刷线路板,金溶出过程受扩散控制。     

硼铁矿中硼镁铁的硫酸法共浸出研究

提出一种采用硫酸酸浸硼铁矿使其中的硼、镁和铁元素共同浸出的方法．硫酸酸浸硼铁矿时,主要是与矿物中的硼镁石[Mg（BO2）（OH）]、磁铁矿[Fe3O4]、蛇纹石[Mg3Si2O5（OH）4]反应．通过热力学分析,验证采用硫酸共溶硼铁矿中的硼、镁和铁元素的可行性,并考察硫酸浓度、液固比、酸浸时间和酸浸温度对酸浸的影响,确定硫酸酸浸硼铁矿的最佳工艺条件：硫酸的质量分数30％,液固比（质量比）8：1,浸出温度90℃,浸出时间120min,搅拌速度大约100r／min．在最佳浸出条件下,硼铁矿中的硼、镁和铁元素的浸出率分别达到99．0％,91．0％,92．9％以上,达到了硼铁矿中硼、镁和铁元素共浸出的目的．     

Zinc leaching from electric arc furnace dust in alkaline medium

Physical and chemical properties of electric arc furnace (EAF) dust from Tianjin seamless Pipe Company were measured and analyzed. The zinc leaching tests in alkaline medium were carried out under variation of leaching agent concentration, leaching temperature, leaching cumulative time and solid-to-liquid ratio. The thermodynamics and kinetics of the zinc leaching process were also analyzed. The results show that the EAF dust contains 10% (mass fraction) zinc and the median particle size is 0.69 μm. The zinc recovery of 73.4% is obtained under the condition of 90 °C, 6 mol/L NaOH, and 60 min leaching time. With the increase of concentration of NaOH and the cumulative time, zinc leaching will be significantly increased. The kinetics study demonstrates that the leaching reaction is chemically controlled and the reaction activation energy is 15.73 kJ/mol.     

亚磷酸钠的生产工艺及结晶动力学研究

采用酸碱中和法制备亚磷酸钠并利用间歇动态法对亚磷酸钠的结晶动力学进行研究. 借助电位滴定法分析亚磷酸中和过程的跃迁点,确定产物主要为亚磷酸氢二钠. 探讨了中和反应温度、摩尔比和亚磷酸浓度等因素对反应产物的影响. 利用激光粒度分析仪测试产品的粒度体积分数,根据粒数衡算和质量衡算关系经矩量变换法回归得到动力学方程,并探索影响产物晶体粒径的因素. 结果表明:亚磷酸氢二钠生成的优化工艺为控制亚磷酸和氢氧化钠的摩尔比为1∶2,亚磷酸的浓度应控制在8.54 mol/L以下,反应温度对其影响很小;亚磷酸和氢氧化钠很容易形成均匀细小的亚磷酸氢二钠,当粒度大于15 μm后,其晶体的生长与粒度无关,获得了亚磷酸氢二钠成核速率方程和成长速率方程;在亚磷酸氢二钠溶液结晶过程中,在介稳区的中部偏超溶解度曲线的位置加入少量粗晶径的晶种,控制蒸发温度在150 ℃左右,在200 r/min搅拌速度下进行结晶,可以得到晶粒较大的亚磷酸氢二钠晶体.     

Effect of stirring on preparation of hollow copolymer particles by alkali/cooling method

Hollow particles were prepared by the treatment of styrene-methacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position (in aqueous phase or at the interface of O/W) and stirring speed (90, 110 and 240 r/min) on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles. Foundation item: Project supported by China Scholarship Council; Project(09JJ3100) supported by Hunan Provincial Natural Science Foundation of China