【作者】 黄雪莉；

【导师】 吕秉玲；

【作者基本信息】 大连理工大学 ， 化学工艺， 2008， 博士

【摘要】 本文针对298.16K下，六元水盐体系Na⁺，K⁺，Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O和其下属的次级体系的液固相平衡及其在我国新疆硝酸钾型卤水矿开发利用中的应用基础进行了研究。依据相图原理并结合实验结果，确定了可以用于实践的简化六元体系相图的表示方法，即以氯化钠为投影顶点的干盐图，图形为正四面体或正三棱柱形，其中点线面各具不同含义。相图的指数单位为mol／mol(2K⁺+Mg²⁺+SO₄^2-+2NO₃^-)或mol／mol(2K⁺+Mg²⁺+2NO₃^-)，水值和氯化钠值根据相图原理进行内插获得。采用等温溶解平衡法并借助于其他手段，测定了298.16K下，上述六元体系下属的五个四元体系(Na⁺，Mg²⁺／／SO₄^2-，NO₃^--H₂O、Na⁺，Mg²⁺／／Cl^-，NO₃^--H₂O、K⁺，Mg²⁺／／Cl^-，NO₃^-H₂O、Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O和Na⁺，K⁺，Mg²⁺／／NO₃^--H₂O)、两个五元体系(Na⁺，Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O、Na⁺，K⁺，Mg²⁺／／Cl^-，NO₃^--H₂O)和该六元体系本身的溶解度数据，并绘出了相应的平衡相图和投影图。298.16K时，Na⁺，Mg²⁺／／SO₄^2-，NO₃^--H₂O体系相图有七个单盐结晶区、十一条单变量溶解度曲线和五个零变量点；Na⁺，Mg²⁺／／Cl^-，NO₃^--H₂O体系相图有四个单盐结晶区、五条单变量溶解度曲线和两个零变量点；K⁺，Mg²⁺／／Cl^-，NO₃^--H₂O体系相图有五个单盐结晶区、七条单变量溶解度曲线和三个零变量点：Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O体系相图有四个单盐结晶区、五条单变量溶解度曲线和两个零变量点；Na⁺，K⁺，Mg²⁺／／NO₃^--H₂O体系相图有三个单盐结晶区、三条单变量溶解度曲线和一个零变量点。298.16K时，Na⁺，Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O体系相图中有十个单盐结晶区和六个零变量点；在氯化钠饱和的区域里，有八个两盐结晶面、十三条单变量溶解度曲线和六个零变量点；单变量溶解度曲线中，有五条反应线；零变量点中一个为共结点，其余为反应点。Na⁺，K⁺，Mg²⁺／／Cl^-，NO₃^--H₂O体系相图中，在氯化钠饱和的区域里，有六个两盐结晶面、九条单变量溶解度曲线和四个零变量点；单变量溶解度曲线中，有两条反应线：零变量点中一个为共结点，其余为反应点。298.16K时，Na⁺，K⁺，Mg²⁺／／Cl^-，SO₄^2-，NO₃^--H₂O体系相图中，在氯化钠饱和的区域里有15个两盐结晶区，25个零变量点；零变量点中只有一个为共结点，其余为反应点。在上述工作的基础上，本文进行了硝酸钾型卤水制取硝酸钾半成品的工艺相图分析计算、卤水的等温蒸发和自然蒸发实验。揭示了不同组成的新疆硝酸钾型卤水蒸发析盐序列。蒸发前期析盐序列为NaCl→NaCl+Na₂SO₄→NaCl+Na₂SO₄+白钠镁矾，后期的蒸发析盐序列依据组成的不同而不同。硝酸钾型卤水矿在等温蒸发和自然蒸发过程中，析盐顺序、液相点组成变化接近相图分析结果，但并不完全依照相图规律移动，表明该六元水盐体系存在介稳行为。制定出了该卤水有效成分提取分离的原则工艺流程，获得了除镁点卤水组成确定的方法。并对其中的盐田自然蒸发过程进行了研究。通过物料衡算和相图推导，建立了以硝酸根损失量为函数，以盐田级数、盐田各级浓度分布为自变量的盐田蒸发数学模型。通过优化，获得了在进行盐田自然蒸发时不同盐田级数和卤水浓度分布规律的关系，同时讨论了盐田级数和沉积盐夹带液相量对硝酸钾损失的影响。硝酸钾型卤水矿进行多级盐田蒸发浓缩时，硝酸根浓度在各级盐田中的分布及盐田的级数对硝酸盐收率有很大影响，合适的盐田级数为3～4级，硝酸根浓度分布因盐田级数而异。更多还原

【Abstract】 In this work, the liquid-solid equilibria of the hexa-component system Na⁺, K⁺, Mg²⁺//Cl^-, SO₄^2-, NO₃^--H₂O, to which the nitrate brine close to Lop Nur of Xinjiang belongs, and its subsystems are studied at 298.16K. Study on them can provide theoretical guidance for the comprehensive utilization of the nitrate deposits in Xinjiang.The isothermal isobaric phase behavior for the system Na⁺, K⁺, Mg²⁺//Cl^-, SO₄^2-, NO₃^--H₂O saturated with NaCl at 298.16K can be used to guide technology. As a result, the free-solvent and free-NaCl projection for the hexa-component system at 298.16K can be plotted in form of regular tetrahedron or trigonal prism. The unit of J（?）necke index for this diagram is mol/mol(2K⁺+Mg²⁺+SO₄^2-+2NO₃^-) or mol/mol(2K⁺+Mg²⁺+2NO₃^-). The values of water and NaCl are obtained by insertion according to principle of phase diagram.At 298.16 K, the phase diagram of Na⁺, Mg²⁺//SO₄^2-, NO₃^--H₂O system consists five invariant points, eleven univariant curves which divide the phase diagram into seven regions of crystallization with one salt; the phase diagram of the system Na⁺, Mg²⁺//Cl^-, NO₃^--H₂O includes four crystallization regions with one salt, five univariant curves and two invariant points; the phase diagram of the system K⁺, Mg²⁺//Cl^-, NO₃^--H₂O at 298.16K includes five crystallization regions with one salt, which are being separated from each other by seven univariant curves which intersect in three invariant points; in the phase diagram of Mg²⁺//Cl^-, SO₄²⁺, NO₃^--H2O, there are two invariant points, five univariant curves and four regions of crystallization with one salt; in the phase diagram of Na⁺, K⁺, Mg²⁺//NO₃^--H₂O, there are one invariant point, three univariant curves and three regions of crystallization with one salt.In the phase diagram of Na⁺, Mg²⁺//Cl^-, SO₄²⁺, NO₃^--H₂O system at 298.16K there are six invariant points, and ten regions of crystallization with one salt. The phase diagram saturated with NaCl consists of eight crystallization regions with two salts, thirteen univariant curves and six invariant points.The phase diagram of the system Na⁺, K⁺, Mg²⁺//Cl^-, NO₃^--H₂O saturated with NaCl at 298.16K, consists of four invariant points, nine univariant curves and six crystallization regions with two salts.In the phase diagram of the system Na⁺, K⁺, Mg²⁺//Cl^-, SO₄^2-, NO₃^--H₂O saturated with NaCl at 298.16K, there are twenty-five invariant points with five salts and fifteen crystallization regions with two salts. One invariant point is co-crystallizing point, the others are reaction points.Based on the studies above and isothermal evaporation experiment, the sequences of salt crystallization during evaporation process at 298.16 K were determined for two kinds of the nitrate brine. At the earlier stage, the sequence of crystallization is NaCl→NaCl+Na₂SO₄→NaCl+Na₂SO₄+Na₂SO₄·MgSO₄·4H₂O; at the later stage, the sequences of salt crystallization are different due to different composition of brine.During the isothermal evaporation experiment at 298.16K and natural evaporation experiment, at the earlier stage, the sequence of crystallization and the changes of composition of liquid are close to the analysis of phase diagram to a great extent for two kinds of typical brine. Metastable phase equilibrium behavior exists in the system Na⁺, K⁺, Mg²⁺//Cl^-, SO₄^2-, NO₃^--H₂O.Under the guidance of the results, basis technological process of comprehensive utilization for the nitrate brine was dertermined. For the sunning process of the brine, a model, in which the lose ratio of NO₃^- is function, the number of the solar ponds and the concentration in the solar ponds are independent variables, has been established by material balance and phase diagram calculation. Combining with industrial data, and utilizing the optimizing method of MatLab, the model has been optimized, the regulation of concentration distribution in the solar ponds has been obtained, and the effect of the number of the solar ponds and the quantity of the brine carried by the salts deposited on the lose ratio of NO₃^- has been also discussed.更多还原