磷酸盐分解钼酸钙的热力学

针对磷酸盐分解钼酸钙的过程,根据同时平衡原理和质量守恒定律,绘制了25℃时Ca-Mo-P-H₂O体系溶解组分的lg_C-pH图,以及不同总磷浓度条件下溶液中总钙、总钼的lg_C-pH图和钼酸钙稳定区.结果表明,在溶液中总磷浓度一定的条件下,随着pH的增大体系中会依次出现H₂MoO₄(s)、CaMoO₄(s)、Ca₅(OH)(PO₄)₃(s)和Ca(OH)₂(s)稳定存在的区域.总磷浓度直接影响到钼酸钙的分解过程,随着总磷浓度的增加,钼酸钙的稳定区域不断减小甚至消失,使得钼酸钙更加易于分解,因此溶液中总钼浓度不断增大,而总钙浓度不断降低;但总磷浓度过高会导致溶液中残留游离含磷离子过高.从热力学角度来看,在钼酸钙分解过程中,添加磷酸盐比碳酸盐更加有利于钼酸钙的分解.     

钼精矿真空分解热力学分析

对钼精矿真空分解过程进行了热力学分析。结果表明,在分解温度1 500~1 800℃、炉内压力0.1~100 Pa条件下钼精矿内的各种含硫化合物都能实现分解或升华,主物相MoS_2遵循逐级分解规律,PbS、As_2S_3直接变为气态挥发,SnS_2、Bi_2S_3分解和挥发的可能性都有,CuS较容易分解为Cu_2S,但Cu_2S分解需要更高的温度和更低的压力。     

高压浸出钼酸钙中钼的实验研究

用高压碱性浸出的方法研究了钼酸钙型矿中钼的浸出性能。通过比较不同浸出剂和研究了不同浸出条件（如温度、时间）对钼浸出率的影响，找到了浸出时的最佳试验条件，实现了钼酸钙矿中钼镍的分离。     

硫化钠分解彩钼铅矿热力学研究

通过热力学计算,在考虑的pH范围内绘制了25℃时彩钼铅矿在总硫浓度为10～11mol／L时溶液中主要离子的1gC—pH图,以及不同总硫浓度条件下溶液铅、钼总浓度的1gC—pH图;据图分析了硫化钠分解钼酸铅矿的热力学条件,并与氢氧化钠分解彩钼铅矿的条件进行了对比,表明硫化钠浸出不但浸出充分,而且对溶液的碱浓度要求相对较弱,还可抑制可溶的羟基配合铅的形成及其对后续工序的不利影响;根据不同硫离子条件下铅、钼离子的1gC—pH图,分析了硫化钠用量对钼浸出的影响。     

硫化钠分解彩钼铅矿热力学研究

通过热力学计算,在考虑的pH范围内绘制了25℃时彩钼铅矿在总硫浓度为10～11mol／L时溶液中主要离子的1gC—pH图,以及不同总硫浓度条件下溶液铅、钼总浓度的1gC—pH图;据图分析了硫化钠分解钼酸铅矿的热力学条件,并与氢氧化钠分解彩钼铅矿的条件进行了对比,表明硫化钠浸出不但浸出充分,而且对溶液的碱浓度要求相对较弱,还可抑制可溶的羟基配合铅的形成及其对后续工序的不利影响;根据不同硫离子条件下铅、钼离子的1gC—pH图,分析了硫化钠用量对钼浸出的影响。     

钼酸钙直接还原动力学的研究

研究了碳与碳化硅两种还原剂对CaMoO4还原动力学的影响规律。结果表明：碳还原CaMoO4的反应级数为一级，反应表观活化能为197kJ／mol，碳的还原性能由于碳化硅，更适宜还原钼酸钙。     

钼酸钙废渣液相催化制备工业氧化钼

采用低温液相催化去钙工艺将含钼40%~41%的钼酸钙转变为氧化钼。结果表明,经处理后的废水钼含量为0.1g/L以下,生产的氧化钼各项指标达到了工业氧化钼行业标准。     

高压氧分解-萃取法回收铜钼中矿中的钼

对从铜钼中矿中回收钼的新工艺进行了研究。其主要过程为：中矿首先在碱性条件下高压氧分解，使钼以钼酸钠的形式进入溶液，而铜保留在残渣中渣作为回收铜的原料，含钼溶液用萃取回收钼。实验表明，在一定条件下，钼和铜的回顾收率分别达到95.6%和99%。     

苛性钠分解黑钨矿的热力学分析

对于不涉及电子得失的复分解反应,除了使用ε-pH图分析问题,也可将竖轴改用来表示浓度变化关系,这样得到了lgC-pH图。本文运用热力学数据,绘制了25℃时Fe-W-H2O体系和Mn-W-H2O体系的溶解组分lgC-pH图。热力学分析结果表明:黑钨矿既可以被酸分解,又可以被碱分解。苛性钠分解黑钨矿时,碱性的增加有利于黑钨矿的分解;只要维持一定的碱度,就可有效进行黑钨矿的碱分解。     

钛酸钙化合物合成热力学与溶出动力学行为

对不同钛酸钙化合物Ca Ti O3、Ca4Ti3O10和Ca3Ti2O7的生成热力学和酸溶动力学进行了研究,结果表明,烧结温度在473~2 000 K时,Ca4Ti3O10、Ca3Ti2O7和Ca Ti O3均能生成;溶出温度在273~573 K时,Ca4Ti3O10、Ca3Ti2O7、Ca Ti O3的酸溶性逐渐减弱.溶出温度在338~358 K范围内,溶出过程受化学反应控制;溶出温度在403~443 K范围内,溶出过程受固膜扩散控制..     

Thermodynamic study of the effect of calcium on removal of phosphorus from silicon by acid leaching treatment

The interaction between calcium and phosphorus in molten silicon was investigated for predicting the removal of phosphorus from silicon by an acid leaching treatment with calcium addition. In the present study, two immiscible liquids of silicon and lead were equilibrated, and the interaction parameter between calcium and phosphorus and the self-interaction parameter of phosphorus in molten silicon at 1723 K were determined.

Thermodynamics of the sublimation of calcium molybdate

The sublimation of CaMoO_4(s) is studied by high-temperature mass spectrometry at 1530–1770 K. CaMoO_4(g) and MoO_3(g) molecules are found to be present in the vapor; their vapor pressure is determined. The pressure of the CaMoO_4(g) molecule vapor is determined to be logp = ? 19 685/T + 5.52. The heat of sublimation ΔH _{s, 0} ^o (CaMoO_4(s)) = 446 ± 40 kJ/mol has been determined using the third law of thermodynamics. The atomization energy of the CaMoO_4(g) molecules is calculated to be ΔH _{at, 0} ^o (CaMoO_4(g)) = 2910 ± 40 kJ/mol.     

Thermodynamic study on calcium treatment of “liquid phase window” and inclusions modification

It is important to study the “liquid phase window” and control non metallic inclusions modification for prevention of submerged entry nozzle blocking during continuous casting. Based on the production practice of medium and high carbon steel in a steel plant, the “liquid phase window” during calcium treatment was studied by combining thermodynamic theoretical calculation and industrial test, which was based on considering the influence of silicon element and temperature on the “liquid phase window”. The results show that the “liquid phase window” varies with T［O］, T［Al］, ［S］ content and temperature, and the low temperature “liquid phase window” must be within the range of high temperature “liquid phase window”, and the silicon content in molten steel has a great influence on the “liquid phase window”. The concepts of “partial liquid phase window” and “complete liquid phase window” are proposed, and the optimum calcium content range of S50C production in a steel plant is determined to be (18-27)×10-6。     

Molybdenum metal by the aluminothermic reduction of calcium molybdate

This investigation deals with a process for extracting molybdenum metal in well consoli-dated form and in good yield from calcium molybdate, by open aluminothermic reduction. Aluminothermic molybdenum has been further processed both by electron-beam melting and by molten salt electrorefining for the removal of aluminum. The final metal compares very favorably with commercial molybdenum obtainable by other routes.     

Thermodynamic properties of calcium hexaboride

The temperature dependence of the heat capacity of CaB₆ in the range 20–2500 K was calculated. The calculated results were confirmed by experimental measurements in the range 198–673 K, and standard enthalpy and entropy values were calculated. A recommended standard enthalpy of formation of CaB₆ was obtained from data in the literature. Equations for the thermodynamic functions of CaB₆ in the range 298.15–2500 K were obtained, which are suitable for the thermodynamic analysis of processes involving calcium hexaboride. Institute for Materials Science Problems, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 63–66, July–August, 1997.     

Thermodynamic analysis of the formation and decomposition of intermetallic hydrides

Powder Metallurgy and Metal Ceramics - The formation and decomposition of LaNi5H6, TiFeH2, Ti2NiH, TiNiH2, Ti2CuH2.7, TiCuH, Ti3AlH3, Mg2NiH4, Mg2CuH3, and ZrMn2.8H4 intermetallic hydrides are...     

钙-5-Br-PADAP-Triton X-100显色反应的研究和应用

在 pH8 0～ 10 0范围内 ,有非离子表面活性剂TritonX 10 0存在下 ,钙与 5 Br PADAP生成 1∶1稳定的有色络合物 ,其最大吸收波长λmax=5 5 5nm ,ε =3 6 7× 10 4,钙量在 0～ 2 0 μg/2 5mL范围内符合比尔定律 方法灵敏 ,准确 ,快速 ,可用于测定球墨铸铁、合金钢中的微量钙