【作者】 张艳丽；

【导师】 张宝林；

【作者基本信息】 郑州大学 ， 化学工艺， 2004， 硕士

【摘要】 由磷矿制取磷酸和磷肥的化学加工方法可分为用无机酸分解和高温处理两大类，其中用硫酸分解磷矿是磷酸和磷肥生产的最主要方法。在酸分解磷矿的生产过程中长期以来存在着诸多问题，比如磷酸生产过程中，不稳定或细小的硫酸钙晶体，不仅使过滤发生困难，洗涤不完全，而且容易在过滤或洗涤过程中结块，影响操作正常进行；生产过磷酸钙、重钙以及尿基复合肥料等含磷产品时，在磷矿颗粒和溶液界面层里会生成过饱和度很高的硫酸钙溶液，从而导致大量细小的硫酸钙结晶生成，沉积于磷矿颗粒表面，所形成的固态膜将反应颗粒包裹起来，增大了磷酸向磷矿表面的扩散阻力，使磷矿的继续分解受到影响，减慢磷矿的分解速度，甚至中止溶解过程。国内外对于改善硫酸钙结晶状况做了不少研究，大都是定性描述添加剂及杂质对结晶的影响，对添加物作用下结晶过程和结晶动力学的研究很少。本课题就是在此基础上提出来的，从定性和定量两个角度出发，研究活化疏松剂作用下酸解磷矿过程中的结晶机理和结晶动力学，并探讨各种因素对其影响情况，为改善产品性能，选择适宜工艺条件，设计合理反应器提供依据。 工业生产中酸解磷矿的过程是一个极其复杂的伴有结晶的反应过程。由于磷矿中杂质的存在，结晶物中除硫酸钙以外还含有其它成分，并且不同的酸解过程所发生的反应和结晶的环境也有所不同，为了避开这些因素的影响，以便对硫酸钙的结晶过程作系统的研究，本课题采用化学纯碳酸钙、硫酸和磷酸为主要原料，模拟工业生产中酸解磷矿过程中的结晶环境，采用自行设计的改进型MSMPR结晶器（等温混合悬浮排料结晶器）模拟工业反应器，在模拟环境下，通过对影响硫酸钙结晶过程的各个因素的系统试验研究与考察，分别讨论了结晶温度、平均停留时间、游离硫酸浓度和活化疏松剂等因素对结晶过程的影响情况，利用数学回归的方法建立二水硫酸钙结晶的宏观动力学方程： G=3.83×10⁵ exp（-1126.89／T）Cs^1.25τ^-1.70 采用郑州大学磷肥与复肥研究所最新开发的活化疏松剂ZL-01为添加物，研究了添加物的加入和用量对结晶过程的影响，采用系数校正的方法进一步建立了活化疏松剂作用下结晶过程的半经验数学模型： G’一5·658·e月0131 .G 结果表明，在本文所讨论的影响结晶过程的4个主要因素中，活化疏松剂的添加对结晶过程的影响最为显著，可以使晶体的成长速率成倍增加，晶体的形状整体改观，结晶质量明显提高;平均停留时间对结晶过程的影响次之;游离酸浓度对结晶过程的影响又次之:温度对结晶过程的影响相对较小。 本课题进行的结晶动力学研究属于酸解磷矿生产过程中的基础理论研究，掌握了活化疏松剂作用下二水硫酸钙结晶的动力学规律，就能够更好的控制结晶环境，更高效、更合理的利用活化疏松剂:就能够预测二水硫酸钙的结晶速度，为结晶器的设计提供理论依据，同时为进一步研究半水硫酸钙和无水硫酸钙的结晶规律打下坚实的理论基础。进而完善了酸分解磷矿生产过程中基础理论，对指导生产具有重要的现实意义。更多还原

【Abstract】 The chemical processing methods of phosphoric acid and phosphorus fertilizer produced by using phosphorus rock can be divided into two big classes: acidulating with inorganic acid and high temperature disposing. In the producing of phosphoric acid and phosphorus fertilizer, the main method is to acidulate phosphorus rock by using sulphuric acid. A great deal of questions exist for a long time while the acid acidulates phosphorus rock, for example: in the production process of the phosphoric acid, the unstable or tiny crystal of calcium sulfate not only make it difficult to filter and wash, but also easily lump in the course of filtering or washing, so that the operating can not be going on normally; While producing the products containing phosphorus, such as calcium superphosphate, heavy calcium superphosphate and carbamide compound fertilizer etc, it will produce highly saturated solution of calcium sulfate in the interface layer between the phosphorus rock particle and the solution, thus lead to produce a large amount of tiny crystals of calcium sulfate. These crystals can deposit on the particle surface of phosphorus rock. The formed solid membrane shall wrap up reactive particles, increase the diffusion obstruction of phosphoric acid to phosphorus rock surface, affect the continual decompose of the phosphorus rock, slow down the speed of resolving of the phosphorus rock, even discontinue the dissolving course. There are many studies about improving calcium sulfate crystallization both at home and abroad, most of which qualitatively describe the impact of the additives and impurities on crystallization. It is rarely researched on the crystallization course and the crystallization kinetics under the function of additives. This subject is put forward on this basis, which study the crystallization mechanism and the crystallization kinetics under the function of additives from two angles of qualitative analysis and quantitative analysis. And it probes into the influences of various kinds of factors on crystallization in order to improve the physical property of the products, choose suitable process conditions and design rational reactor.The course of acidulating phosphorus rock is an extremely complicated reaction course with the crystallization in industrial production. Because of the existence of impurities in the phosphorus rock, there are also other compositions besides calcium sulfate in the crystallization. And different responses have different environments of the crystallization. In order to avoid the influences of these factors and makesystematic study of the calcium sulfate crystallization course, this subject simulates crystallization environment in the industrial production by adopting the raw materials of calcium carbonate, sulphuric acid and phosphoric acid and the improved MSMPR crystallizer. Under the imitating environment, the influences of many factors on crystallization course of calcium sulfate are discussed including crystallization temperature, the average staying time, dissociative sulphuric acid density and active & porous agents(APA), etc. And the macro-dynamics model of the crystallization of dehydrate calcium sulphate is set up by utilizing mathematics method:G = 3.83 X 105 exp(-1126.89/T) Cs1.25 -1.70This thesis has studied the impact of APA on crystallization from two aspects, which are the joining and consumption of APA. Further, the half experience mathematics model of crystallization course is set up at the base of the function of APA.G’= 5.658 .CA0.131.GThe result shows that the impact of APA on crystallization course is most remarkable in four main factors. It can make increase crystal growth speed, change the form of crystals wholly and improve crystallization quality obviously. The impact on crystallization course takes second place in the average time of staying; in turn, dissociative sulphuric acid density, crystallization temperature.The Crystallization dynamics is a part of the basic theoretical researches during the course of discomposing phosphorus rock with更多还原