Influence of crystal structure on mechanical activation effect

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｗｅｌｌａｃｋｎｏｗｌｅｄｇｅｄｔｈａｔｉｎｔｅｎｓｅｍｅｃｈａｎｉｃａｌａｃ ｔｉｏｎｍａｙｃａｕｓｅｒｅｍａｒｋａｂｌｅｉｎｃｒｅａｓｅｉｎｒｅａｃｔｉｖｉｔｙｏｆｓｏｌｉｄｓ .Ａｌｏｔｏｆｂａｓｉｃｒｅｓｅａｒｃｈｉｎｆｉｅｌｄｓｏｆｇｅｏｌｏｇｙ[1] ,ｍｅｔａｌｌｕｒ ｇｙ[2 6] ,ａｓｗｅｌｌａｓｃｈｅｍｉｃａｌｅｎｇｉｎｅｅｒｉｎｇ[3 ] ,ｈａｓｓｈｏｗｎｔｈａｔｐｒｅｓｓｕｒｅａｎｄｓｔｒｅｓｓａｒｅｃｏｎｃｅｎｔｒａｔｅｄａｔｔｈｅｃｏｎｔａｃｔｓｉｔ…     

含铝废LiFePO4正极粉在H2SO4溶液中的浸出性能

研究含铝废LiFePO4(LFP)正极粉中LFP和Al的浸出行为及浸出动力学.考察温度(273～368 K)、搅拌速率(200～950 r/min)、反应时间(0～240 min)、酸料比(0.1:1～1:1 mL/g)和液固比(3:1～9:1 mL/g)对浸出过程的影响.结果表明,反应物浓度和温度对Al浸出影响较大....     

机械活化对铟铁酸锌溶解动力学及物化性质的影响

以人工合成的高纯度铟铁酸锌为研究对象,采用搅拌球磨对其进行机械活化。以锌的浸出率为评价指标,研究不同活化试样在硫酸溶液中的浸出特性和溶解动力学,并利用X射线衍射仪、扫描电镜、激光粒度分析仪和比表面积分析仪分别考察机械活化对铟铁酸锌晶体结构、颗粒形貌、粒度和比表面积的影响。结果表明:机械活化使铟铁酸锌的物化性质发生明显改变,并由此提高了铟铁酸锌的反应活性。经机械活化30和60 min后,铟铁酸锌与硫酸反应的表观活化能由未活化时的76.4 kJ/mol分别降至58.6和51.8 kJ/mol,表观反应级数也由原来的0.79分别降至0.62和0.59。未活化铟铁酸锌的酸溶过程受化学反应控制,活化后则为混合控制。     

Leaching kinetics of antimony-bearing complex sulfides ore in hydrochloric acid solution with ozone

The leaching kinetics of Sb and Fe from antimony-bearing complex sulfides ore was investigated in HCl solution by oxidation–leaching with ozone. The effects of temperature, HCl concentration, stirring speed and particle size on the process were explored. It is found that the recoveries of Sb and Fe reach 86.1% and 28.8%, respectively, when the reaction conditions are 4.0 mol/L HCl, 900 r/min stirring speed at 85 °C with <0.074 mm particle size after 50 min leaching. XRD analysis indicates that no new solid product forms in the leaching residue and the leaching process can be described by shrinking core model. The leaching of Sb corresponds to diffusion-controlled model at low temperature (15–45 °C) and mixed-controlled model at high temperature (45–85 °C), and the apparent activation energies are 6.91 and 17.93 kJ/mol, respectively. The leaching of Fe corresponds to diffusion-controlled model, and the apparent activation energy is 1.99 kJ/mol. Three semi-empirical rate equations are obtained to describe the leaching process.     

Leaching of chromite ore in concentrated KOH by catalytic oxidation using CuO as catalyst

CuO was used as a catalyst in the concentrated KOH solution to enhance the leaching of chromium from the chromite ore. The impacts of temperature, KOH-to-chromite ore mass ratio, CuO-to-chromite ore mass ratio, and gas flow rate on the chromium leaching rate were investigated. The results indicated that CuO played an important role in improving the chromium leaching rate. The leaching rate reached 98% after leaching for 6 h when CuO was applied, whereas it was only 60.8% without CuO under the same reaction conditions: temperature 230 °C, KOH-to-ore mass ratio 6:1, stirring speed 700 r/min, gas flow rate 1 L/min. According to the kinetics study, the catalytic oxidation was controlled by surface chemical reaction and the activation energy was calculated to be 15.79 kJ/mol when the temperature was above 230 °C. In contrast, without CuO, the rate-determining step was external diffusion and the apparent activation energy was 38.01 kJ/mol.     

湿法炼锌废渣中硫脲浸出银的动力学

探讨了从湿法炼锌废渣中用硫脲浸出回收银的浸出反应动力学,从这种难浸的含银炼锌废渣中用硫脲浸出回收银,浸出反应是一种典型的氧化还原反应并可充分进行,同时,通过动力学推导得出,从湿法炼锌废渣中用硫脲浸出银的反应动力学模型为收缩核动力学模型,同时计算出浸出活化能为13．26kJ/mol。该模型反映了浸出过程中控制整个反应速率的决定步骤是固膜扩散速率,并较好地说明了浸出机理。     

表面机械活化粉煤灰提取氧化铝及其动力学研究

采用高能球磨活化粉煤灰,并对球级配、球料比、转速以及球磨时间进行正交试验,将经不同时间活化的粉煤灰与Na2CO3按一定比例煅烧溶出,得到Al2O3.通过测试分析,研究了高能球磨活化各工艺参数对Al2O3溶出率的影响,得到了最优化工艺条件,并对Al2O3溶出过程的动力学进行了验证分析.结果表明:当表面机械活化6h、溶出温度90℃、液固比L/S=6、硫酸浓度4 mol/L时,效益最高;此反应属于收缩未反应芯模型,表观活化能为60.87 kJ/mol,反应级数为0.1701.     

Effect of temperature,oxygen partial pressure and calcium lignosulphonate on chalcopyrite dissolution in sulfuric acid solution

The pressure leaching mechanism of chalcopyrite was studied by both leaching tests and in-situ electrochemical measurements. The effects of leaching temperature, oxygen partial pressure, and calcium lignosulphonate, on copper extraction and iron extraction of chalcopyrite pressure leaching were investigated. The leaching rate is accelerated by increasing the leaching temperature from 120 to 150 °C and increasing oxygen partial pressure to 0.7 MPa. The release of iron is faster than that of copper due to the formation of iron-depleted sulfides. Under the optimal leaching conditions without calcium lignosulphonate, the copper and iron extraction rates are 79% and 81%, respectively. The leaching process is mixedly controlled by surface reaction and product layer diffusion with an activation energy of 36.61 kJ/mol. Calcium lignosulphonate can effectively remove the sulfur passive layer, and the activation energy is 45.59 kJ/mol, suggesting that the leaching process with calcium lignosulphonate is controlled by surface chemical reactions. Elemental sulfur is the main leaching product, which is mixed with iron-depleted sulfides and leads to the passivation of chalcopyrite. Electrochemical studies suggest that increasing the oxygen partial pressure leads to increasing the cathodic reaction rate and weakening the passivation of chalcopyrite.     

Effect of processing history of pyrite on its leaching kinetics

1　INTRODUCTIONThereliableknowledgeaboutleachingkineticofmineralsisofgreatimportancefordevelopinghy drometallurgical processes .Butmanyatime ,re searchersobtainedscatteredresultsforthesamepro cess .Forexample ,theapparentactivationenergyforthedigestionofpyritebyoxygeninsulfateacidsolu tionrangeswidelyfrom 39to 84kJ/mol[13] .Usual ly ,thedifferenceisascribedtothevarietyinmineralresource ,chemicalcompositionand ,accuracyofex perimentalmethods.Howeveronlythisisstillunsat isfactoryforexplain…     

Effect of mechanical activation on dissolution kinetics of neutral leach residue of zinc calcine in sulphuric acid

Neutral leach residue of zinc calcine (NLRZC) was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation (MA) induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H₂SO₄ concentration were found to be 0.34, 0.30, and 0.29, respectively.     

Leaching kinetics of selenium from copper anode slimes by nitric acid-sulfuric acid mixture

The leaching kinetics of selenium from copper anode slimes was studied in a nitric acid-sulfuric acid mixture. The effects of main parameters on selenium leaching showed that the leaching rate of selenium was practically independent of stirring speed, while dependent on temperature and the concentrations of HNO₃ and H₂SO₄. The leaching of selenium includes two stages. The activation energy in the first stage is 103.5 kJ/mol, and the chemical reaction is the rate controlling step. It was almost independent of H₂SO₄ concentration and dependent on HNO₃ concentration since the empirical reaction order with respect to HNO₃ concentration is 0.5613. In the second stage, the activation energy is 30.6 kJ/mol, and the process is controlled by a mixture of diffusion and chemical reaction. The leaching of selenium was almost independent of HNO₃ concentration.     

微波作用下铝酸钙炉渣非等温浸出动力学

研究了微波作用下铝酸钙炉渣非等温浸出动力学，考察了不同微波辐射功率对炉渣中氧化铝浸出率的影响以及相应微波功率下反应体系温度随时间的变化规律。结果表明：该浸出动力学过程的控制步骤为界面化学反应控制，表观反应活化能为40kJ／mol左右；微波作用可改变反应的频率因子，对反应活化能影响不明显；随着微波辐射功率的增大，频率因子增加，宏观表现出微波功率的增加对反应有促进作用。     

含Ti高炉渣酸解动力学

研究了363-383 K范围内,使用稀硫酸(20％-60％)酸解含Ti高炉渣的酸解动力学.实验条件下的化学反应过程为化学反应控制,用生成固体产物层的未反应核缩减模型可描述为1-(1-x)1/3=kMBcnAt/(roρwB)=Kt.将实验结果与模型关联,求出的酸解反应级数n=1.222,表观活化能为87.01 kJ/mol,K=5.090×104×(10.59+1/r0)cA1.222e-10.465×103/T.通过实验验证,TiO2酸解率低于90％时与模型很好符合.     

Preparation of sodium manganate from low-grade pyrolusite by alkaline predesilication–fluidized roasting technique

Low concentration alkaline leaching was used for predesilication treatment of low-grade pyrolusite. The effects of initial NaOH concentration, liquid-to-solid ratio, leaching temperature, leaching time and stirring speed on silica leaching rate were investigated and the kinetics of alkaline leaching process was studied. The results show that silica leaching rate reached 91.2% under the conditions of initial NaOH concentration of 20%, liquid-to-solid ratio of 4:1, leaching temperature of 180 °C, leaching time of 4 h and stirring speed of 300 r/min. Shrinking-core model showed that the leaching process was controlled by the chemical surface reaction with activation energy E_a of 53.31 kJ/mol. The fluidized roasting conditions for preparation of sodium manganate were optimized by the orthogonal experiments using the desiliconized residue. The conversion rate of sodium manganate was obtained to be 89.7% under the conditions of silica leaching rate of 91.2%, NaOH/MnO₂ mass ratio of 3:1, roasting temperature of 500 °C and roasting time of 4 h, and it increased with the increase of silicon leaching rate.     

焙烧氟碳铈矿硫酸浸出稀土的动力学(英文)

研究了硫酸浸出德昌稀土与天青石共伴生矿的焙烧矿过程。考查粒度、搅拌速度、硫酸浓度和温度对稀土浸出率的影响,并对稀土的浸出动力学进行分析。在选定的浸出条件下:粒径0.074～0.100mm、硫酸浓度1.5mol/L、液固比8:1、搅拌速度500r/min,稀土浸出反应受内扩散控制,表观活化能为9.977kJ/mol。     

湿法炼锌净化渣酸浸的动力学

对湿法炼锌净化渣的浸出动力学进行了研究,并探讨了硫酸浓度、反应温度、粒度等对钴、锌浸出率的影响规律。从动力学的角度分析了整个浸出过程,得到优化条件：液固比50：1(mL/g),硫酸浓度100 g/L,反应温度70°C,粒度75~80μm,反应时间20 min。在此优化条件下钴的浸出率为99.8%,锌的浸出率为91.97%。结果表明：在硫酸体系中钴的浸出符合不生成固体产物层的“未反应收缩核”模型。通过 Arrhenius 经验公式求得钴和锌表观反应活化能分别为11.693 kJ/mol和6.6894 kJ/mol,这表明浸出过程受边界层扩散控制。     

低钒转炉钢渣提钒湿法工艺的动力学研究

为了提高湿法浸出低钒钢渣中钒的浸出效率,并对湿法浸出低钒钢渣中钒提供理论依据,从动力学角度分析整个浸出过程。考察温度、液固比、硫酸质量分数和搅拌速率对浸出过程的影响。研究结果表明:在90℃、液固比为10?1以及硫酸浓度6.0mol/L时,浸取9h,低钒钢渣中钒的浸出率可达到95.3%。通过正交实验和动力学推导,得到描述浸出过程的经验方程,低钒钢渣湿法浸出钒的动力学模型为收缩核动力学模型,浸出过程的表观活化能为12.794kJ/mol,该模型表明浸出过程中的控制步骤取决于固膜扩散速率。提高温度、液固比和硫酸质量分数,均可加速钒的浸出速度,提高钒的浸出率。     

Reductive acid leaching of valuable metals from spent lithium-ion batteries using hydrazine sulfate as reductant

Hydrazine sulfate was used as a reducing agent for the leaching of Li, Ni, Co and Mn from spent lithium-ion batteries. The effects of the reaction conditions on the leaching mechanism and kinetics were characterized and examined. 97% of the available Li, 96% of the available Ni, 95% of the available Co, and 86% of the available Mn are extracted under the following optimized conditions: sulfuric acid concentration of 2.0 mol/L, hydrazine sulfate dosage of 30 g/L, solid-to-liquid ratio of 50 g/L, temperature of 80 °C, and leaching time of 60 min. The activation energies of the leaching are determined to be 44.32, 59.37 and 55.62 kJ/mol for Li, Ni and Co, respectively. By performing X-ray diffraction and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy, it is confirmed that the main phase in the leaching residue is MnO₂. The results show that hydrazine sulfate is an effective reducing agent in the acid leaching process for spent lithium-ion batteries.     

Dechromization and dealumination kinetics in process of Na2CO3-roasting pretreatment of laterite ores

A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na₂CO₃ roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na₂CO₃-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99% and 82%, respectively, under the optimal particle size of 44–74 μm, Na₂CO₃-to-ore mass ratio of 0.6:1, and temperature of 1000 °C. Dechromization within the range of 600–800 °C is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 °C with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8% Ni and 95.6% Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.     

铟的还原浸出动力学及分步沉淀选择性分离（英文）

开展硫化锌精矿还原浸出高铁锌浸出渣高效浸铟及浸出液中铟选择性分离的研究。结果表明：在固体物料粒度74～105μm、反应温度90℃、浸出时间300 min、硫酸浓度1.4 mol/L的条件下,铟的浸出率达95%以上。采用收缩核模型对还原浸出动力学进行分析,不同条件下的浸出实验结果表明反应受穿过固体产物层的扩散控制,活化能为17.96 k J/mol,相对于硫酸浓度的反应级数为2.41。铁粉置换沉铜过程铜和砷的沉淀率均达99%以上。98%以上的铟从含高亚铁离子浓度的硫酸锌溶液中选择性分离,获得铟含量约为2.4%的富铟渣,经酸浸-萃取-电积工艺流程进一步处理后可得到纯铟。