铝电解电解质初晶温度及分子比槽前在线测定仪

一种铝电解电解质初晶温度分子比槽前在线测定仪。本发明通过功能集成，能在实际数据的基础上建立符合实际情况的电解质成分与初晶温度的关系，电解质成分与其分子比的关系，电解质初晶温度与其分子比的关系，从而实现了通过测定电解质初晶温度这个物理量来测定电解质的分子比。本发明包括信号采集系统的炉体和温度传感器；     

铝电解质初晶温度检测及其数模拟合的研究

直接测定了铝电解质实际样品的初晶温度。根据分析结果拟合出该体系初晶温度与分子比数学模型。试验了不同材质的高温传感器及保护套管 ,石墨坩埚作盛样器 ,对其测温的准确度作了验证 ,并对其形状作了改进 ,使传感器的使用寿命得到了延长。     

直接测定铝电解质初晶温度的研究

用冷却曲线法测定了实际铝电解质的初晶温度。为确证测温的准确性 ,与差热分析的结果进行了对比。自配电解质样品与文献所述的初晶温度值相当符合 ,实际样品的初晶温度要低于文献值。分析了产生误差的原因 ,对温度测定的重复性也作了研究。操作方式对电解质测温的重复性有很大的影响 ,处于同一操作情况下测得的结果吻合。冷却曲线法测定铝电解质初晶温度快速、准确 ,可为初晶温度的在线检测提供依据。     

基于响应曲面法的Na3AlF6-Al2O3-LiF-KF-CaF2体系初晶温度实验研究

本文在实验室条件下,研究了氧化铝中Li、K、Ca对电解质初晶温度和电解槽热平衡的影响,应用响应曲面法,建立了Na₃AlF₆-Al₂O₃-LiF-KF-CaF₂五元系初晶温度数学模型,得出结论：在实验条件范围内,对于电解质初晶温度的影响大小依次为：LiF的主效应>分子比的主效应>KF的主效应>CaF₂的主效应。     

新型功能介孔材料的合成及其对铅离子吸附性能研究

2O3-3 %CaF2-KCl体系的初晶温度,并对测定数据进行回归分析,得到初晶温度的回归方程。研究结果表明,在铝电解质中添加氯化钾能够降低电解质的初晶温度。本文旨在获得铝电解质初晶温     

铝电解质初晶温度测定装置及初晶点数模的研究

电解质初晶温度是铝电解生产过程中的一个重要参数,本文研究了直接测定铝电解质初晶温度的装置。整套装置由进样系统、高温炉、炉温控制系统、计算机测控系统组成。采用新装置可以在线实时读取数据并自动绘制温度曲线,获取结果方便准确,减少了人为误差。同时采用均匀设计法进行试验设计,考察了Na3AlF6-Al2O3-MgF2-CaF2-LiF五元体系的初晶温度,并由此建立了该体系初晶温度的数学模型。由此模型得出的预报值与实测值之间的绝对误差在±5℃以内。     

高锂钾铝电解质的初晶温度

为了研究Na₃AlF₆-AlF₃-Al₂O₃-CaF₂-LiF-KF体系的初晶温度,基于130组高可靠性铝电解质初晶温度的文献数据,采用非线性拟合法得到了适用于计算高锂钾复杂铝电解质体系初晶温度的经验公式.采用差热分析法测定了32组铝电解质的初晶温度,与本文中的公式计算值进行对比分析,结果表明,计算值与实验值之间的最大绝对误差仅为2.7℃.该经验公式可用于预测高锂钾铝电解质的初晶温度.     

铝电解三度寻优控制技术应用的可行性

在铝电解的生产过程中,电解质温度、电解质初晶温度和过热度(简称"三度")的控制是核心.现有计算机只进行氧化铝浓度的控制,氧化铝浓度仅是影响电解质初晶温度和阳极效应系数的一个因素,对"三度"的控制很难形成统一的认识和标准化的管理,要取得好的电解生产指标是比较困难的."三度寻优"控制技术是以计算机为核心对电解槽的电解质温度、电解质初晶温度和过热度进行控制而形成的一套标准化生产管理模式.     

电解质体系变化对初晶温度的影响研究

在分析国内多家企业电解质成分和测定初晶温度的基础上,通过统计分析和拟合计算,分析了电解质成分与初晶温度之间的关系,给出了电解质体系变化对初晶温度的影响规律,并改进了Solheim A和Rolseth S初晶温度经验数模拟合计算公式,提高了计算值与实测值的吻合度。     

水浸液电导法测定新型铝电解质的分子比

将低温烧结-水浸液电导法用于低温铝电解所用的碱性和含钾新型铝电解质分子比的测定。考察了碱性和含钾电解质对于电导法以及电导法计算公式的适用性,并对水浸液的电导温度系数进行回归拟合,建立了碱性和含钾新型铝电解质分子比测定的计算公式。研究表明, 新型铝电解质通过配入过量NaF并经低温烧结后充分溶解在水溶液中,用工业型电导率仪可快速测定其电导率,用重新拟合计算公式可计算碱性和含钾的新型铝电解质的分子比。本方法适用于电解质分子比为1.8～4.0、KF含量为0～15%的碱性和含钾的新型铝电解质分子比的测定,测定结果的相对标准偏差小于0.40%。     

Liquidus Temperatures of Cryolite Melts With Low Cryolite Ratio

The effect of calcium fluoride on liquidus temperatures of the cryolite melts with a low cryolite ratio (CR) was studied. The systems KF-NaF-AlF₃ and KF-LiF-AlF₃ with CRs of 1.3, 1.5, and 1.7 have been investigated. The liquidus curves of systems containing CaF₂ are different and depend on the K/(K + Na) and K/(K + Li) ratios. In potassium cryolite with CRs of 1.3 and 1.5, the calcium fluoride solubility is low and increases with NaF (LiF) concentration.     

Liquidus Temperature Depression in Cryolitic Melts

The electrolyte in Hall-Héroult cells for the manufacture of primary aluminum nominally contains only cryolite (Na₃AlF₆) with additions of AlF₃, CaF₂, and Al₂O₃. However, impurities are present, entering the process with the feedstock. The effect on the liquidus temperature by the impurities cannot be calculated correctly by the well-known equation for freezing-point depression in binary systems simply because the electrolyte cannot be regarded as a binary system. By extending the equation for freezing-point depression to the ternary system NaF-AlF₃-B, it appeared that the acidity of the impurity B plays a major role. Some calculations were made using an ideal Temkin model, and for most types of impurities, the effect on the liquidus temperature will be larger in an industrial electrolyte than what can be estimated from the equation for freezing-point depression in cryolite. Experimental data on the liquidus temperature in the system Na₃AlF₆-AlF₃-Al₂O₃-CaF₂-MgF₂ show that the effect of MgF₂ on the liquidus temperature increases strongly with decreasing NaF/AlF₃ molar ratio, and it is suggested that MgF₂ forms an anion complex, probably MgF ₄ ^2? .     

Investigation of Freeze-Linings in Aluminum Production Cells

The molten cryolite bath creates chemically a very aggressive environment in the Hall–Héroult cell, and thus, the formation of a protective solid layer (freeze-lining) on the cell wall is essential for the operation of the present cell designs. To provide further information on the formation of the freeze-lining deposit in this system, laboratory-based studies were undertaken using an air-cooled probe technique The effects of process conditions, i.e., time, bath agitation, and superheat on the microstructures, morphologies of the phases, and the phase assemblages adjacent to the deposit/bath interface were investigated. A detailed microstructural analysis of the steady-state deposits shows that a dense sealing primary-phase layer of cryolite solid solution was formed at the interface of the bath deposit for the process conditions examined. The formation of sealing primary-phase layer at the bath/deposit interface explicitly indicates that the deposit/liquid bath interface temperature is equal to that of the liquidus of the bulk bath. The experimentally investigated liquidus temperature and subliquidus equilibria differ significantly from those previously reported.     

Solubility of aluminum in cryolite-alumina electrolytes

The complex influence that additives of aluminum, calcium, lithium, and potassium fluorides have on the total solubility of aluminum in the cryolite-alumina melt is studied. The investigations were performed at a constant overheating of the melt saturated by alumina (15°C relative to the liquidus temperature). The aluminum solubility was determined via the prolonged holding of metal in the melt at a specified temperature with the subsequent sampling of the specimen, which was rapidly frozen, and the metal content in it was determined by a gas-volumetric analysis. It was seen that, as the cryolite ratio (CR) decreases from 2.5 to 2.2, the aluminum solubility in the electrolyte drops by a factor of 1.7, while the further decrease in CR to 2.1 does not cause its substantial variation. The introduction of 3 wt % LiF and 5 wt % KF into the melt with a constant overheating of the melt substantially decreases the metal solubility, namely, by a factor of 2.9 and 1.5, respectively.     

Thermodynamics of the System NaF-AlF3: Part V. Solid Solution in Cryolite

Electrical resistivity measurements have been used to demonstrate the existence of solid solutions of AlF₃ in the high-temperature form of cryolite above the transition at 565°C. An expression was derived for the resistivity of single-phase mixtures as a function of composition and temperature, and it was then used to deduce the composition at the solid-solid phase boundaries. At the NaF-cryolite eutectic temperature (880°C) the boundary lies at 74.8 mole pct NaF, and at the chiolite peritectic temperature (737°C) the other boundary lies at 74.4 mole pct NaF. The variation of composition with activity of NaF is reasonably consistent with the hypothesis that solid solution leads to formation of AlF ₄ ¹ ions and cation vacancies. On this basis extrapolation is made for the solid-liquid boundaries, and the solid solution region is found to touch the liquidus at 74.0 mole pct NaF. On the above hypothesis the anomalous heat content of cryolite between 888°C and the melting point can be accounted for.     

Interaction of sintered aluminum nitride with the KF-AlF3 melt at 700–800°C

Interaction kinetics of the aluminum nitride-based sintered composite material with the potassium cryolite melt with the cryolite ratio KO = 1.3 at 700–800°C is investigated by the continuous weighing method. It is established that the composite is almost unaffected by the melt at t = 700°C. The corrosion rate increases as the temperature increases. The material interacts with the molten salt through its oxidation stage by oxygen dissolved in the melt. This is also accompanied by the dissolution of oxygen-containing impurities that are initially present in the material. No interaction of sintered aluminum nitride with the melt under study was observed in the absence of the oxidant and with the concentration of alumina dissolved in cryolite close to saturation.     

Na3AlF6-AlF3-Al2O3-CaF2-KCl系铝电解质初晶温度的研究

采用常用的步冷曲线法测量电解质的初晶温度。采用最小二乘法对实验数据进行二次拟合,得到了初晶温度的回归方程。同时,采用二次回归正交试验设计的方法,测定了Na₃AlF₆-AlF₃-3 %Al₂O₃-3 %CaF₂-KCl体系的初晶温度,并对测定数据进行回归分析,得到初晶温度的回归方程。研究结果表明,在铝电解质中添加氯化钾能够降低电解质的初晶温度。本文旨在获得铝电解质初晶温度的基础数据,为提高电流效率、降低生产成本服务。     

关于低分子比冰晶石取代氟化铝问题的探讨

本文对低分子比冰晶石和氯化铝在调节铝电解质分子比过程中，进行了理论分析和理论计算，表明暂得不出低分子比冰晶石能取代氟化铝的结论。     

Understanding the bottom buildup in an electric copper smelting furnace by thermodynamic calculations

Thermodynamic calculations were used to investigate the liquidus temperature of the slag and the possible influence on the buildup formation in an electric copper smelting furnace. The impact of parameters such as Fe/SiO₂ ratio, partial pressure of oxygen and the content of the oxides ZnO, Al₂O₃ and Cr₂O₃ in the slag were investigated with respect to the liquidus temperature of the slag. Results show that the chromium content in the slag has the greatest impact on the liquidus temperature and on the formation of solid particles. The characterisation of the buildup done earlier showed that spinel phases were among the dominating phases. This is supported by the thermodynamic calculations in the present paper, where the chromite solid solution was found to be the primary precipitation phase.