Kinetics of leaching lithium from α-spodumene in enhanced acid treatment using HF/H2SO4 as medium

An enhanced leaching of Li from α-spodumene was carried out using a mixture of hydrofluoric and sulfuric acid (HF/H₂SO₄) as the medium. Based on the optimized leaching conditions, the leaching kinetics of Li was investigated in an ore/HF/H₂SO₄ ratio of 1:3:2 g:mL:mL with leaching temperature ranging from 50 to 100 °C. The results indicate that the leaching kinetics of Li fitted well with a model based on the shrinking core model. In addition, the leaching rate of Li was controlled by chemical reactions and diffusion through the product layers. The apparent activation energy E_a was calculated to be 32.68 kJ/mol. Solid films were formed because of the generation of insoluble products such as cryolithionite (Na₃Li₂Al₂F₁₂), cryolite (Na₃AlF₆), calcium fluoride (CaF₂), potassium cryolite (K₂AlF₅), aluminum fluoride (AlF₃), and fluorosilicates (Na₂SiF₆ or KNaSiF₆). Furthermore, the effects of the ore/HF ratio and leaching temperature on the leaching behavior of Li, Al and Si were investigated. The results indicate that the ore/HF ratio and leaching temperature could clearly affect the distribution of HF molecules on the leaching of Li, Al and Si, which are important for the selective leaching of Li over Al and Si with this fluorine-based chemical method.     

锂云母连续管式反应器中混酸H2SO4+H2SiF6体系强化溶出锂

采用硫酸(H2SO4)和氟硅酸(H2SiF6)的混酸浸出剂强化锂云母中锂的浸出.氟硅酸(H2SiF6)作为氢氟酸的副产物,可以提供反应所需的氟化氢(HF)分子.而氟化氢是氟硅酸实际参与反应的主要成分,对锂的强化溶出具有关键作用.探究矿石/硫酸/氟硅酸质量比、硫酸和氟硅酸浓度、浸出温度(40～80℃)、浸出时间(15～7...     

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....     

H2SO4分解铁-FeCl3浸出焙烧金精矿中金

采用硫酸分解焙烧金精矿,金从黄铁矿中解离的同时金得到了富集,可采用氯化铁溶液非氰浸出金。研究了硫酸浓度及过量系数、分解温度对铁分解率的影响,优化工艺条件为,焙烧温度180 ℃,反应时间90 min,硫酸过量系数1.2,在此条件下,铁分解率为92.14%,金含量从原来的51.7 g/t提高到106.1 g/t;研究了反应温度、液固比对氯化铁溶液浸出硫酸浸出渣中金的影响,优化浸出条件为,液固比1.5,80 ℃浸出90 min,在此条件下,金浸出率96.8%。     

木薯淀粉三元接枝共聚物对钢在H2SO4溶液中的缓蚀性能研究

将两种烯类单体烯丙基磺酸钠(SAS)和丙烯酰胺(AA)同时接枝共聚在木薯淀粉(CS)上制备出木薯淀粉三元接枝共聚物CS-SAS-AAGC;用失重法、电化学法、扫描电镜(SEM)和接触角测试研究了CS-SASAAGC对冷轧钢在H2SO4溶液中的缓蚀性能。结果表明,CS-SAS-AAGC的缓蚀性能远远优于CS,SAS和AA,最大缓蚀率可超过90%,且在钢表面的吸附符合Langmuir吸附等温式。缓蚀性能随温度和酸浓度的增加而逐渐下降,但随腐蚀浸泡时间的延长而基本保持不变。CS-SAS-AAGC为抑制阴极为主的混合抑制型缓蚀剂;添加CS-SAS-AAGC后钢电极表面的电荷转移电阻显著增大,腐蚀微观形貌显著降低,且具有较强的疏水性。     

向日葵盘提取物在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用

以超声辅助法提取得到的向日葵盘提取物(HALE)为缓蚀剂,采用腐蚀浸泡试验、电化学试验研究HALE在0.5mol/L H2SO4溶液中对碳钢的缓蚀作用。结果表明:HALE对碳钢缓蚀效果良好,缓蚀率随HALE加量增加而增大,但随温度升高而降低;HALE在碳钢表面的吸附符合Langmuir吸附模型,是以物理吸附为主的混合吸附;电化学测试结果表明HALE是偏阳极混合抑制型缓蚀剂。     

高铬铁素体不锈钢447在浓H_2SO_4溶液中的腐蚀电化学行为

采用电化学技术研究了高铬铁素体不锈钢447(以下称447不锈钢)在40~80℃,85%~98%H_2SO_4(质量分数)溶液中的腐蚀电化学行为。结果表明:在80℃,85%~95%H_2SO_4溶液中,447不锈钢呈现出周期性的活化-钝化腐蚀的特性,这种电化学振荡主要是由自钝化态下形成的p型半导体钝化膜的产生和溶解与电化学反应的耦合而导致的;在40~80℃,85%~98%H_2SO_4溶液中,447不锈钢的耐蚀性随温度的升高和H_2SO_4含量的减少而降低;随温度的升高,波动性加强,H_2SO_4质量分数小于98%时,随其含量的升高波动性加强,H_2SO_4质量分数不小于98%时,可使447不锈钢在H_2SO_4溶液中处于稳定的钝态,447不锈钢在自钝化态下的腐蚀主要由电荷转移步骤所控制。     

十二烷基二羟乙基氧化胺在0.5 mol·L~(-1) H_2SO_4中对A3钢的缓蚀性能

通过失重法、电化学方法和量子化学计算法研究了十二烷基二羟乙基氧化胺(OAE-12)在0.5mol·L~(-1)H_2SO_4中对A3钢的缓蚀性能和作用机理。结果表明,在0.5mol·L~(-1)H_2SO_4中OAE-12能同时抑制A3钢的阴、阳极反应,缓蚀性能显著,当OAE-12质量浓度仅为200mg·L-1时,失重试验所得缓蚀率可达93.59%,且失重法、动电位极化曲线法、电化学阻抗谱法测试结果具有一致性;通过量子化学计算结果可知,OAE-12缓蚀作用机理可能是源于其分子内的氮、氧与钢表面的铁的相互作用。     

Degradation characteristics of Ti/(IrO2+Ta2O5) coating anodes in H2SO4 solution

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｂａｓｅｄＩｒＯ2 ｃｏａｔｉｎｇａｎｏｄｅｓｗｅｒｅｗｉｌｄｌｙｕｓｅｄｉｎｅｌｅｃｔｒｏｃｈｅｍｉｃａｌｉｎｄｕｓｔｒｙｆｏｒｔｈｅｉｒｈｉｇｈｅｌｅｃｔｒｏｃａｔａｌｙｔｉｃａｃｔｉｖｉｔｙａｎｄｓｔａｂｉｌｉｔｙ[1] .Ｉｎａｎｅｘｔｒｅｍｅｃｏｎｄｉｔｉｏｎ ,ｓｕｃｈａｓｈｉｇｈ ｓｐｅｅｄｅｌｅｃｔｒｏｄｅｐｏｓｉｔｉｏｎ ,ｈｏｗｅｖｅｒ ,ｔｈｅｓｔａｂｉｌｉｔｙｏｆＩｒＯ2 ｉｓｎｏｌｏｎｇｅｒｓａｔｉｓｆｉｅｄ .Ｔｈｅｒｅｆｏｒｅ ,ｔｈｅｍｏｄｉｆｉｃａｔ…     

在H2SO4-HCl-H2O复合体系中氧化浸出镍钼矿冶炼烟尘中的硒

对在H2SO4-HCl-H2O复合体系中氧化浸出镍钼矿冶炼烟尘中的硒进行热力学分析,确定从镍钼矿冶炼烟尘中浸出硒的新工艺及其最优技术参数.采用XRD对镍钼矿冶炼烟尘及其浸出渣进行表征.结果表明:在最佳技术条件下,硒浸出率达到98%,浸出渣含硒0.16%(质量分数);冶炼烟尘中硒以单质形式存在,未见硒及其化合物出现,表明烟尘中的硒浸出较完全;浸出渣主要由SiO2、CaSO4、A12SiO5、As2O3和KAlSi3O8组成.     

Corrosion and wear behaviors of Al-bronzes in 5.0% H2SO4 solution

Steady-state corrosion and wear behaviors of two Al-bronzes, Cu-14Al-X and QAl9-4, in 5.0% H2SO4 solution were investigated. It is found that wear loss of bronzes in 5.0% H2SO4 solution is lower than that in water or in air, namely, it exhibits negative synergy between corrosion and wear. Further analysis shows that corrosive solution plays an important role in cooling of specimen during the sliding wear to prevent the reduction of the surface hardness of specimen, induced by frictional heat. On the other hand, the bronzes suffer a de-alloying corrosion, and a noble copper subsurface and patina form on the specimen surface in corrosive solution, which has a passive function for further corrosion. The noble copper subsurface experiences strain hardening during the corrosion and wear, resulting in the increase of the surface hardness thus the increase in wear resistance.     

锆合金在HCl和H2SO4溶液中的耐蚀性能研究

采用化学浸泡、电化学测试和物理检测技术,研究了HCl和H2SO4溶液中锆合金的腐蚀行为.结果表明,锆合金在还原性的HCl和低浓度H2SO4溶液中,具有优异的耐蚀性,而在高浓度的氧化性H2SO4溶液中腐蚀速率显著增大.物理检测结果显示,腐蚀的锆合金表面均匀地覆盖着弥散分布的微小颗粒状ZrO2.还原性的HCl和低浓度H2SO4溶液中ZrO2膜保持了原有的致密性,增强了锆合金的耐蚀性能.而高浓度H2SO4溶液中,在其强氧化作用下,锆合金基体/膜界面处不断生成ZrO2.当膜增加到一定厚度时,氧化膜的晶格参数与金属的晶格参数不一致,产生内应力,降低了氧化膜的附着力,直至氧化膜破裂,露出新鲜的锆合金表面.继之,新鲜的锆合金再次被氧化,以此循环往复,导致锆合金在浓H2SO4溶液中腐蚀加剧.     

Synthesis and character of spinel LiMn2O4

1　INTRODUCTIONTheincreasingconcernsonportableelectricele mentsdemandmoreandmoreelectrochemicalener gy .Countriesallovertheworldhaveputlargequan tityofmanuallabors ,materialresourcesandfinancialresourcesonbasicresearchanddevelopmentonnewtypeofrechargeablebatteries[1,2 ] .However ,thisnewtypeofbatteriesisbasedonstudyinganddevel opingperfectperformanceofmaterials ,especiallyonmaterialsofthelithiumbatteries.LixMn2 O4 cathodematerialshavebeenwidelystudiedoverthelasttwodecadesasapotentialcand…     

Solid reaction mechanism of CaHPO4·2H2O + CaCO3 with and without yttria

The effect ofyttria on the solid reaction mechanism ofa CaHPO4·2H2O + CaCO3 system at different temperatures was experimentally stud-ied. The samples with and without yttria were subjected to thermogravimetric/differential scanning calorimetry measurement. The samples were heat treated at the temperatures corresponding to the peaks on the DSC spectra, and the resulted phase compositions were identified by X-ray diffraction. The transformation mechanism was deduced by comparing the phases obtained at different temperatures. The results show that the transformations at below 1073 K are not affected by yttria, but all those at above 1073 K are completely altered. The formation tem-perature of hydroxyapatite decreases by 134 K, and the decomposition temperature increases by 38 K. The polymorphous transformation of Ca3(PO4)2 from β phase to α phase increases by 47 K. The thermodynamic properties of the transformations at above 1073 K are also modi-fied by the addition of yttria; that is, the endothermal peaks are substituted by exothermal peaks.     

Synergistic effect of iodide ions and bark resin of Schinus molle for the corrosion inhibition of API5L X70 pipeline steel in H2SO4

The synergistic effect of bark resin of Schinus molle (BRSM) and iodide ions in 0.5 M sulfuric acid has been studied for the first time by potentiodynamic polarization and electrochemical impedance spectroscopy measurements; also, the surface morphology has been analyzed by scanning electron microscopy–energy-dispersive X-ray spectroscopic analysis in the present work. The results show that the BRSM and iodide ions have an evident synergistic inhibition effect in a 0.5-M sulfuric acid solution. The adsorption of the BRSM/iodide ion system follows the Langmuir adsorption isotherm and acts as a mixed-type inhibitor in sulfuric acid. The BRSM/iodide ion system is an effective inhibitor for API5L X70 pipeline steel in the 0.5-M sulfuric acid solution. The maximum percentage inhibition efficiency is equal to 99% at 1 g/L BRSM + 2 mM KI.     

Effect of ferric ions in AISI 316L stainless steel pickling using an environmentally‐friendly H2SO4‐HF‐H2O2 mixture

A mixture of hydrogen peroxide, sulphuric and hydrofluoric acids has been used as pickling solution at pH 2.0 for AISI 316L austenitic stainless steel (SS). The stability of the H₂SO₄‐HF‐H₂O₂ mixture is assessed varying the ferric ions content from 0 to 40 g/L, the temperature from 25 to 60°C, and with and without stirring of the pickling solution. The AISI 316L SS pickling rate at 50°C was 2.6 and 0.2 mg/dm² day (mdd) in the absence and presence of 40 g/L ferric ions, respectively. p‐toluene sulphonic acid (PTSA) has been used as stabiliser of hydrogen peroxide.     

硫酸体系有色金属电沉积用3D-Pb阳极的制备与性能（英文）

研究Pb²⁺浓度、电流密度、沉积时间和温度对沉积Pb结构的影响。在低Pb²⁺浓度条件下(～0.15 mol/L),Pb沉积物呈杨桃状,而在高Pb²⁺浓度条件下(≥0.30 mol/L),Pb沉积物呈立锥状。进一步对比研究杨桃状Pb阳极(Cara-Pb)、立锥状Pb阳极(Pyra-Pb)和Pb阳极的氧化膜层和阳极电位。在160 g/L H₂SO₄溶液中恒流极化(50 mA/cm²)72 h后,Pyra-Pb阳极氧化膜层厚度大于Cara-Pb和Pb阳极,进而显著减缓金属基底的晶界腐蚀。此外,Pyra-Pb阳极氧化膜层具有更大表面积和更高Pb O₂含量,因此,极化72 h后Pyra-Pb阳极电位较Cara-Pb和Pb阳极的低40mV。综上,在Pb阳极表面构建立锥状3D-Pb结构具有降低电沉积能耗、延长阳极寿命的潜力。     

Synthesis of large diamond crystals with C3H8N4O2 as organic additive under HPHT conditions

Diamond crystals were successfully synthesized in a NiMnCo-C system by adding Malonic acid dihydrazide (C₃H₈N₄O₂) as an organic additive. The synthesized conditions in a series of experiments were about at 1300 °C–1400 °C and 6.0 GPa–7.0 GPa. The color, morphology, and inclusions of the synthetic diamond crystals were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscope and Raman spectroscope, respectively. The color of the synthesized diamonds changes from light yellow to green with increasing amounts of C₃H₈N₄O₂. The morphology of the synthesized diamonds exhibited triangular shape with abundant {111} faces. The FTIR spectra indicated that the nitrogen concentration increased whereas the hydrogen and oxygen concentration decreased with increasing concentration of the C₃H₈N₄O₂ additive. The Raman peak positions exhibited a systematic downshift with increasing amounts of C₃H₈N₄O₂ additive. According to the synthesized resultant, with increased the content of the C₃H₈N₄O₂ additive, the quality of synthesized diamond gets worse. It is interesting that the diamond content more nitrogen and less hydrogen and oxygen with increasing the C₃H₈N₄O₂ additive. By studying the effects of nitrogen, hydrogen and oxygen coexistence on the synthesis of diamond, it is would to speculate that the natural diamond nucleation and growth environment may be content more nitrogen source and less hydrogen and oxygen.     

Hydrothermal synthesis of Zn4SO4(OH)6·5H2O and its application as anode material for nickel/zinc batteries

The anode material Zn4SO4 (OH)6 · 5H2O for nickle/zinc batteries was synthesized by hydrothermal method and was identified by XRD techniques. TG/DAT measurements reveal that the products lose lattice water at 145 ℃ and decompose to 3ZnO · ZnSO4 at 274 ℃. Cyclic voltammetry and recharging/discharging results show thatCV curves have good symmetry, the ratio of oxidation area to reduction area for each curve is about 1, and the peak potential EPa and EPc have little change with the scanning rate. At 50th circle, more than 65 % of theoretical capacity is obtained while at the same condition, zinc oxide electrode only remains 35% of theoretical capacity.