含钒钛转炉渣氧压酸浸过程V-Ti-H2O系的电位-pH图

为了分析含钒钛转炉渣氧压酸浸过程的热力学特点,根据高温水溶液中计算标准摩尔吉布斯自由能和活度系数的经验公式,通过计算得到了氧分压0.5MPa、对应离子的质量浓度0.1mol/kg、温度60～200℃条件下V-Ti-H2O系的电位-pH图。在pH〈2的酸性条件下,可溶性V3＋,VO2＋,VO2＋的稳定区几乎全部包含在TiO2的稳定区范围内,随着温度由60℃升高到200℃,钒、钛稳定共存区对应的氧化还原电位逐渐增大,pH逐渐降低。钒、钛稳定区的共存特点从热力学角度为转炉渣采用氧压酸浸工艺通过一步酸浸将钒浸出的同时使钛富集在渣中提供了理论依据。含钒钛转炉渣的氧压酸浸实验结果表明,在浸出温度140℃、氧分压0.5MPa、粒度0.055～0.075mm、液固比15：1、浸出时间120min、搅拌速度500r/min、初酸浓度200g/L的条件下,钒的浸出率为96.87%,钛的浸出率为8.76%。钒与钛通过氧压酸浸工艺能够得到有效分离,实验结果与热力学计算结果一致。     

基于同时平衡原理的Au-I~--H_2O系热力学分析

采用同时平衡原理对Au-I--H2O系的浸金热力学进行分析,分别研究溶液与固体Au以及Au I沉淀与固体Au平衡时的φ-p H关系、Au I存在条件和溶液中含金组分的变化规律。结果表明:随着溶液中含金组分的总浓度cT(Au)的降低或含碘组分的总浓度cT(I-)的增加,还原电位φsol/Au迅速降低,Au3+/Au2O3的平衡p H值增大,非常有利于金的碘化浸出;随着溶液中cT(I-)逐渐增加,出现Au I沉淀且其沉淀量呈先增大后减小的趋势;在cT(Au)为1×10-4 mol/L的条件下,当溶液中cT(I-)浓度大于0.0021 mol/L时,可避免Au I沉淀的生成,金主要以Au I2-络合离子形式存在。Au-I--H2O系的浸金热力学分析为金的高效碘化浸出提供了理论依据。     

铜水体系电位-pH图与发电机内冷水pH调节防腐

研究了铜水体系电位－pH之间的关系.结果表明,以10-6.2mol/L作为划分腐蚀发生与否的界限较合适,并据此作出了铜水体系的新的简化电位－pH图.     

Li-Mn-H2O系热力学分析

绘制了25.℃时Mn-H2O与Li-Mn-H2O系的ε-pH图, 并对锂离子电池用正极材料锰酸锂的湿化学制备以及溶液中锂的回收问题从热力学上进行了分析, 指出了可能的技术途径和对策; 计算发现, LiMn2O4完全或部分地占据了各种价态锰离子化合物的稳定区域, 在水溶液中的稳定性很好. 这对湿法制备LiMn2O4十分有利; 而LiMnO2的稳定性较差, 仅在溶液中维持较高锂离子浓度时才可存在. 湿法制备LiMnO2的条件较为苛刻; 对于从溶液中回收锂, 锰的固体氧化物如MnO2无疑是极佳的吸附剂, 理论上有很高的回收率. 吸附的锂宜采用提高溶液电势的方法进行氧化性解吸.     

转炉钒渣氧压酸浸过程V-Fe-H_2O系的电位—pH图

根据高温水溶液中计算各反应电位、pH及电解质活度因子的经验公式,通过热力学计算,得到氧分压为0.5 MPa、对应质量浓度为0.1mol/kg的离子活度以及温度分别为60、100、150和200℃条件下V-Fe-H2O系的电位—pH图。在pH<2的酸性条件下,V3+、VO2+和VO2+的稳定区一直位于Fe3+和Fe2+的稳定区范围内。随着温度由60℃提高到200℃,可溶性钒铁离子稳定共存区的pH值逐渐降低,氧化还原电位逐渐提高,钒铁尖晶石及氧化物的稳定区变化不大。热力学研究结果表明:采用氧压酸浸工艺能够将转炉渣中的钒充分浸出,但不能通过一步浸出在提钒的同时将钒、铁分离,浸出液还需要进一步净化来生产钒制品。转炉钒渣氧压酸浸的实验结果表明:在浸出温度140℃、氧分压0.5 MPa、粒度0.055～0.075 mm、液固比15-1(体积与质量比)、浸出时间120 min、搅拌速度500 r/min及初酸浓度200 g/L H2SO4的条件下,钒的浸出率为96.87%,铁的浸出率为89.25%,实验结果与热力学计算结果相符合。     

Fe系E(pE)-pH图及随时间变化规律

利用Fe-H2O二元平衡图的原理,测定铁在不同环境中长时间的腐蚀规律,通过研究Fe-H2O系平衡图在水,人造海水、盐酸、氢氧化钙中长时间观测溶液的氧化还原电位和pH值在腐蚀区和钝化区之间的变化,探索铸铁在不同溶液中防锈的可能途径.     

Li-Fe-P-H2O系热力学分析

运用同系线性规律对Li-Fe-P-H2O系中缺少的LiFePO4和Li3PO4的ΔG■进行估算。结合已有的热力学数据,运用φ—pH图的绘制原理,得到25℃时Li-Fe-P-H2O系在不同浓度下的φ—pH图。结果表明,在水溶液中,LiFePO4具有较大的热力学稳定区域,这对湿法制备LiFePO4很有利。根据所绘制的热力学平衡图,详细讨论了各种LiFePO4软化学制备方法的可行性途径,并就液相法制备LiFePO4可能的技术途径和条件进行分析,为在水溶液中用软化学法制备LiFePO4提供理论依据。     

电位—pH平衡图的习惯表达方法

电位-PH图是著名的比利时腐蚀学家M.布拜(M.Pourbaix)教授于1938年首先提出来的,也被人称之为Pourbaix图.该图以元素的电极电位(E)为纵坐标,水溶液的pH值为横坐标,将一给定的元素-H_2O体系中全部反应物和生成物的热力学平衡条件,即元素、元素离子和元素化合物的稳定化条件,集中地表示在这个图上.在金属腐蚀过程中,电位是控制金属离子化过程的因素,表征溶液酸度的pH值则是控制腐蚀产物的稳定性的因素.应用这两个参数,可以将金属与水溶液之间大量的复杂的均相和非均相化学反应以及电化学反应在给定条件下的平衡关系简单明了地图示在一个很小的平面或空间里.这对于推断反应的可能性及生成物的稳定性,特别是对金属腐蚀的研究,提供了极大的方便.几十年来,布拜及其合作者已绘制了周期表中90多个元素在室温下的二元E-pH图,并向多元以及高温方向发展,为腐蚀科学作出了卓越的贡献.     

Bi^3＋—Cl^——H2O系热力学平衡

运用同时平衡原理和质量平衡原理对Ｂｉ＾３－Ｃｌ－Ｈ２Ｏ体系进行热力学分析和计算，在此基础上绘制了Ｂｉ＾３＋－Ｃｌ－Ｈ２Ｏ体系在２５℃下的各种涫淀物的平衡浓度对数－ＰＨ图，分析确定了各大相沉淀物稳定存在的ＰＨ。结果表明，溶液中铋离子和硝酸根离子的浓度及溶液的ＰＨ值是影响各固相稳定存在的重要参数。由热力学图得出，可以直接从溶液中沉淀的Ｂｉ２Ｏ３，要得到高纯工的ＢｉＯＣｌ必须严格控制溶液的ＰＨ范围。     

298.15K下Li-Ti-H_2O系φ—pH图及Li_4Ti_5O_(12)的合成

运用双参数模型和同系线性规律对Li2Ti3O7、Li4Ti5O12和Li4TiO4的标准生成吉布斯自由能进行估算,并绘制在298.15 K时,不同离子浓度下Ti-H2O系和Li-Ti-H2O系的φ—pH图。结果表明:在水溶液中,Li4Ti5O12在pH为4.1～13.7之间具有较大的热力学稳定区域,从热力学角度预测了从水溶液合成Li4Ti5O12的可能性,并通过实验在pH为9～10之间,采用TiCl4水溶液强制水解法制备出纯相尖晶石Li4Ti5O12,验证水溶液中合成Li4Ti5O12的可行性。     

Potential-pH diagrams of Cr-H2O system at elevated temperatures

The potential—pH diagrams of the Cr-H₂O system at temperatures of 298, 323, 373 and 423 K were established through thermodynamic calculation with coupling of experimental results. The potential—pH diagram at 298 K agrees well with the previously reported results. Based on the potential—pH diagrams of the Cr-H₂O and Fe-H₂O systems, IR spectra and XRD pattern, the existence forms of iron in the potassium chromate were analyzed, and the methods of iron removal were investigated. The results show that the existence forms of iron in the potassium chromate are potassium ferrate. These results are instructive and helpful to the hydrometallurgical processing of chromite ore.     

POTENTIAL-pH DIAGRAMS OF Al-H_2O SYSTEM

ＰＯＴＥＮＴＩＡＬｐＨＤＩＡＧＲＡＭＳＯＦＡｌＨ２ＯＳＹＳＴＥＭ①ＺｅｎｇＷｅｎｍｉｎｇ，ＣｈｅｎＮｉａｎｙｉＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＭｅｔａｌｕｒｇｙ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｓｈａｎｇｈａｉ２０００５０...     

Primary study of the isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ in air

The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction (XRD) and in situ high-temporature XRD quantitative analysis, in addition to scanning electron microscopy measurement, the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem, the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area, the approximate composition areas of two two-phase regions and one three-phase region, (L2 + Cr), (L2 + M), and (L1 + L2 + Tr), were determined. Moreover, the precise composition areas of both of the three-phase regions (L2 + Cr + M) and (L2 + M + A) were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.     

Primary study of the isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ in air

The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction （XRD） and in situ high-temperature XRD quantitative analysis,in addition to scanning electron microscopy measurement,the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem,the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area,the approximate composition areas of two two-phase regions and one three-phase region,（L2＋Cr）,（L2＋M）,and （L1＋L2＋Tr）,were determined. Moreover,the precise composition areas of both of the three-phase regions （L2＋Cr＋M） and （L2＋M＋A） were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.     

硫化镍精矿熔炼的热力学分析

广泛地搜集了ＮｉＣｕＦｅＳＯ 体系热力学数据, 严格地进行了筛选, 并充分考虑各物质的分解温度, 借助已开发的优势区图自动绘制系统, 完整地绘制了ＮｉＳＯ, ＣｕＳＯ, ＦｅＳＯ, ＮｉＣｕＳＯ 和ＮｉＦｅＳＯ几个体系不同温度下的ｌｇｐＳＯ２ —ｌｇｐＯ２ 优势区图。从一系列优势区图发现, 在高温下（１ ５００ Ｋ以上） , 镍冶炼过程的稳定成分主要是金属、低价金属硫化物、低价金属氧化物, 其它物种均会发生分解。从理论上重新阐述了镍高温火法熔炼的热力学原理。     

Thermodynamic equilibrium of CaSO4-Ca（OH）2-H2O system

The pc-pH diagrams of the CaSO4-Ca(OH)2-H2O system and its two subsystems at 298.15 K were constructed according to the theory of thermodynamic equilibrium. The interaction characteristics between the solubility of CaSO4(s) and Ca(OH)2(s) can be found out from the diagrams. CaSO4(s), Ca(OH)2(s) and solution coexist when the pH value of solution is about 13.2. CaSO4(s) with the minimum solubility of 0.411 g/L is in equilibrium with solution when the pH value is lower than 13.2, and Ca(OH)2(s) with the minimum solubility of 2.749 g/L is in equilibrium with solution at the pH value over 13.2, which provides a theoretical basis for the treatment and reuse of industrial wastewater, especially for the wastewater containing sulfate which can be treated by lime-milk neutralization.     

Equilibrium of hydroxyl complex ions in Pb^2＋-H2O system

The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions (pc) vs pH, the distribution ratio of lead hydroxyl complex ions (αn) vs pH, and the conditional solubility product of Pb(OH)2 vs pH in the Pb2+-H2O system. The relationship between the equilibrium concentration of each kind of lead hydroxyl complex ions in equilibrium with Pb(OH)2(s) and pH value was shown in the system. The minimum solubility of lead is at the pH value of 10.096-10.997. The distribution ratio of each kind of the lead hydroxyl complex ions is determined as a function of the pH value and the total lead concentration ([Pb]T). The diagram for the conditional solubility product, pKSP vs pH, shows that each kind of lead hydroxyl complex ions existing in the system is dependent upon an optimized pH value at the established concentration of [Pb]T, and that pKSP reaches the minimum at the pH value of 10.3-11.2. The results can provide a theoretical basis for removing lead ions from wastewater by the neutralization and hydrolyzation technology.     

温度和O2含量在CO2/H2S/O2体系中对输气管道的腐蚀行为研究

目的 为给新疆油田输气管道的腐蚀防控提供依据,揭示L360NS钢在CO₂/H₂S/O₂共存体系中不同O₂含量(物质的量分数0%～2%)和不同温度(60～180℃)工况下的腐蚀行为。方法 以新疆油田HN区块输气管道为研究背景,基于现场运行工况设计高温高压反应釜试验方案,选择L360NS钢为试样进行失重法、腐蚀产物表征、基体形貌表征、腐蚀缺陷深度测试等试验。结果 随O₂含量增大,L360NS钢的均匀腐蚀速率从0.299 1 mm/a逐渐增大到0.912 3 mm/a。试样表面出现腐蚀缺陷,且随O₂含量升高有逐渐扩大的趋势,腐蚀产物膜呈楔形、多方晶体状,大小不一。温度(60～180℃)升高,L360NS钢的均匀腐蚀速率从2.103 4 mm/a逐渐降低到0.457 0 mm/a,腐蚀缺陷逐渐减小,产物膜结构由稀松多孔逐渐转为致密。结论 由于O₂具有强氧化性及去极化效应,导致在产物中出现Fe的高价氧化物,结构疏松多孔。另一方面,H_2...     

Fe2O3／Al体系制备Al2O3粒子增强铝基复合材料

对Fe2O3与Al合金反应合成法制备Al2O3粒子增强铝基复合材料进行了研究.对所得复合材料进行组织观察,OM观察发现Fe以网状合金相形式存在;SEM观察显示原位颗粒分布均匀,颗粒细小,直径小于0.5 μm;TEM观测显示Al2O3颗粒边角圆滑、界面干净,与基体结合良好.对复合材料进行力学性能测试,硬度略有提高,室温抗拉强度略低,300℃时抗拉强度达到92.18 MPa,比基体提高了26%.