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题名	铬盐清洁生产新技术体系中联产高纯铬酸酐与硝酸钾工艺的基础研究
作者	陈恒芳
学位类别	博士
答辩日期	2004
授予单位	中国科学院过程工程研究所
授予地点	中国科学院过程工程研究所
导师	李佐虎
关键词	高纯铬酸配 清洁生产 相图 重铬酸钾 硝酸钾 热力学
其他题名	Fundamental Study on the Preparation of High-purity Chromium Trioxide and Potassium Nitrate in the New Cleaner Chromate Production Process
学位专业	化学工艺
中文摘要	中国科学院过程工程研究所开发的低温熔盐液相氧化法铬化工清洁生产集成技术首次实现了资源的高效利用、废弃物零排放和反应介质内部循环的工业化学体系，与铬盐传统生产工艺相比，降低了反应温度和能耗，勿须外购纯碱与硫酸，从而也大幅度降低了铬盐的生产成本。本文根据钾系铬盐清洁生产新工艺的技术集成要求，以铬盐系列的重要产品CrO3清洁生产为对象，以其母产品重铬酸钾为原料，研究了硝酸分解重铬酸钾制备高纯铬酸醉并联产具有高附加值的KNO3的清洁生产一绿色工艺过程，以取代现行的重铬酸钠硫酸熔融转化的传统工艺。本文主要研究内容和结论如下：（1）对硝酸分解重铬酸钾联产高纯铬酸配和硝酸钾的工艺过程进行了可行性实验研究，首先确定了工艺流程，并研究了反应、分离等主要单元操作中反应物初始配料组成、浓度和温度等，对反应过程和产物分离的影响，初步确定了工艺参数。此联产工艺的主反应是在溶液中进行的复分解反应，工艺过程的关键在目标产物的有效分离与精制纯化。实验结果表明，分离CrO3宜在硝酸浓度为72.2％左右溶液中进行，而分离KNO3宜在35-40％的稀硝酸中实现。由此工艺可制得纯度）99.9％的铬酸配和比工业一级品纯度更高的硝酸钾产品。（2）通过实验测定并绘制了由硝酸分解重铬酸钾反应体系的子体系CrO3-HNO3-H2O（0℃）及KZCr2O7-CrO3-H_2O（25℃）和主体系KZCr2O7-CrO3-KNO3-HNO3-H2O（0℃、25℃、45℃）的相图。（3）由实验测得的相图分析结果确定了最优的工艺流程，并确定了Cr6＋、K+一次结晶率最大的条件，可实现反应物闭路循环全利用的清洁生产理想目标。根据相图分析结果，原料初始配料量K2Cr2O7：HNO3摩尔比为1：4.95，反应完成后冷冻至0℃分离KNO3，能达到最大的钾结晶率；原料初始配料量K2Cr2O7：HNO3摩尔比为1：5.44时，反应完成后冷却至45℃分离CrO3，能达到最大的铬结晶率。分析结果与实验结果吻合。优化后的工艺流程是一个密闭循环的清洁工艺，整个过程物料平衡。工艺流程中各单元操作所用的设备已初步选型。（4）对硝酸分解重铬酸钾反应体系的相图进行热力学研究。从应用角度出发，讨论了有关电解质溶液的统计热力学理论、半经验模型以及含挥发性电解质（如HNO3，HCl）的混合水盐体系的汽液平衡及其和固液平衡同时关联计算等现状和进展。结合硝酸分解重铬酸钾反应体系的具体组成，在考虑溶液中离子缔合平衡后，将以摩尔分率为基准的Clegg＆Pitzer（1992）模型进行扩展应用。关联了35个单一电解质水溶液体系的活度系数实验数据，并可在全浓度范围内关联常压下HNO3-H2O和HCl-H2O体系的汽液平衡，结果与实验数据吻合。扩展后的模型能用于关联含挥发性强电解质的三元混合体系的固液平衡或与其汽液平衡同时关联，如HNO3-KNO3-H2O和HNO3-NaNO3-H2O体系的固液平衡关联结果与实验测得的溶解度数据基本吻合，HCl-KCl-H2O体系的固液平衡与汽液平衡同时关联的结果也很接近实验结果。关联了硝酸分解重铬酸钾反应体系K2Cr2O7-CrO3-KNO3-HNO3-H20（25℃）复杂体系的固液平衡，绘制其相图与实验结果进行比较，结果一致。
英文摘要	The cleaner production technology of chromate (CPTC) developed by the Institute of Process Engineering, Chinese Academy of Sciences, based on the original kernel technology of the sub-molten liquid oxidation in an alkaline medium, implements an industrial chemical system with comprehensive utilization of the valuable components in chromite, the zero emission of the chromium containing residue and reaction medium recycling in inner system for the first time. Compared with the conventional technics, it doesn't need to buy calcined soda and sulfuric acid as raw materials and it improves the conversion of chromium in chromite ores greatly and decreases the reaction temperature and the energy consumption and therefore cost of production significantly. The thesis exploited a cleaner production technique to manufacture chromium trioxide (CrO3) of high purity tlirough nitric acid (HNO3) decomposing potassium dichromateaccording to the requirement of potassium-route CPTC, whose prime product is 7, to replace the traditional conversion method of sodium dichromate (Na2Cr2O7) by sulfuric acid (H2SO4). The main study contents and the conclusions are as follows: 1. The process flow of jointly producing CrC>3 and potassium nitrate (KNO3) by using HNO3 to decompose K2Cr2O7 was explored and the process parameters, such as the concentration and the mixture ratio of reactants, the temperature of reaction and so on, were determined. The main reaction of this technique is a double decomposition reaction conducted in solution. Therefore, the key procedures are the effectively segregation of reaction product and the refinement of objective production. The results of experiment shows that CrO3 should be separated when the concentration of nitric acid is about 72.2% and for KNO3, 35-40% is suitable. By the technique developed in the thesis, the CrO3 product with purity higher than 99.9% and the KNO3 byproduct better than industrial first-class quality can be obtained. 2. The solubilities of system K2Cr207 - CrO3 - KNO3 - HNO3 - H2O(0°C, 25 °C ^ 45 °C) and its subsystem CrO3 - HNO3 - H2O(0°C)and K2Cr207 - CrO3 - H2O(25°C)were determined by experiment and the phase diagrams were plotted according to the experimental results. 3. To achieve the maximum crystallization ratio of Cr and K, the effective production conditions were decided and the material balance was made by analyzing the phase diagrams of system K2Cr2O7 - CrO3 - KNO3 - HNO3 - H2O (0°C. 25°C, 45°C). If the initial mole proportion of raw materials K2Cr207 : HNO3 is 1:4.95, the solution after reaction finished is frozen to 0°C to crystallize KNO3, the maximum crystallization ratio of K is achieved. Similarly, if the initial mole proportion of K2Cr207: HNO3 is 1:5.44, the reacted solution is cooled to 45 °C to crystallize CrO3, the maximum crystallization ratio of Cr is achieved. The analysis outcome coincides with the experimental result. The efore, the objective of a cleaner production process with closed recycling and total utilization of reactants can be realized. The equipment for all unit operation was recommended. 4. The thermodynamics research of phase diagram of the reaction system of decomposing K2Cr2O7 by HNO3 was made. Firstly, the statistical thermodynamics theories and semi-empirical equations related to electrolyte solution were reviewed and discussed. Also, the vapor-liquid equilibrium (VLE) and/or solid-liquid equilibrium (SLE) correlations of solution which include volatile strong electrolytes like HNO3 and HC1 were summarized. Then, combined with the concrete system, after considering ion association equilibrium in solution, the Clegg & Pitzer (1992) model was extended. The single electrolyte model parameters of 35 electrolytes were correlated by their activity coefficient experimental data. In addition, the VLE of HNO3 - H2O and HC1 - H2O of the whole concentration range were successfully correlated. The extended model can be used to fit VLE and/or SLE of ternary system including volatile strong electrolytes. The SLE of HNO3 - KNO3 - H2O and HNO3 - NaNO3 -H2O and the VLE and SLE of HC1 - KCi - H2O were fitted, whose results coincide with the experimental data well. The SLE of system K2Cr207 - CrO3 - KNO3 - HNO3 - H2O (25 °C) was correlated and the phase diagram was plotted, which is in accordance with the experimental results.
语种	中文
公开日期	2013-09-16
页码	134
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1391]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	陈恒芳. 铬盐清洁生产新技术体系中联产高纯铬酸酐与硝酸钾工艺的基础研究[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2004.

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