【作者】 陈宇；

【导师】 崔鹏；

【作者基本信息】 合肥工业大学 ， 化学工程， 2013， 硕士

【摘要】 本文以湖北宜昌磷矿为主要研究对象，采用磷硫混酸化学浸提法对磷矿进行脱镁研究。通过脱镁试剂的选择与优化，对脱镁工艺参数进行研究，并选择合适的动力学模型，设计动力学实验，利用SEM、EDX及XRD等微观表征方法对混酸脱镁过程及动力学进行研究与分析，推导脱镁反应控制步骤，为磷矿脱镁研究及工业应用提供技术支持。在利用单一硫酸、磷酸及一定配比的磷硫混酸对磷矿进行脱镁浸提时，混酸浸提的脱镁效果明显优于单酸浸提脱镁，混酸组成为：V（H₂SO₄）/V（H₃PO₄）为3/7，体积浓度为15%。且在混酸浸提过程中，矿石颗粒表面生成CaSO₄·2H₂O和Ca（H₂PO₄）2两种晶体交替堆积，在Ca（H₂PO₄）2的析出与溶解的动态平衡中，有利于促进脱镁反应的进行及磷损失的控制。利用V（H₂SO₄）/V（H₃PO₄）为3/7，体积浓度为15%的混酸对MgO含量为3.0%左右的磷矿进行浸提，优化工艺条件，结果表明在pH值为2³，反应液固比为2cm³/g,反应温度为50oC，搅拌速率为200rpm下脱镁反应30min后，固相中MgO含量均降至1.0%以下， P₂O₅含量均有所增加，且CaO/P₂O₅<1.6，MgO/P₂O₅<0.08，能够满足湿法磷酸生产的需要。对磷硫混酸浸提的脱镁过程及动力学进行研究与分析可知，未反应收缩芯模型能够准确的描述磷硫混酸脱镁过程。混酸脱镁速率与混酸中硫酸用量、混酸浓度、反应液固比、粒径与不同粒径下MgO含量的乘积以及反应温度成正比，脱镁反应表观活化能大于40kJ·mol，脱镁反应过程整体表现为化学反应控制。更多还原

【Abstract】 Yichang phosphate rock from Hubei province was selected as the standard samples.The process of magnesium impurities removal from phosphate rock through leaching bymixture of phosphoric and sulfuric acid was investigated. The main factors in the process ofmagnesium impurities removal from phosphate rock by mixture of phosphoric and sulfuricacid were studied based on the selected leaching agents selection and optimization.Scanning electronic microscopy, energy dispersive and X-ray spectroscopy were utilizedto characterize the intermediate and final products. The kinetics of magnesium removalfrom phosphate rock through leaching by mixture of phosphoric and sulfuric acid wasinvestigated in order to provide technological support to industrial applications.The process of magnesium impurities removal from phosphate rock through leachingby sulfuric acid,phosphoric acid and mixture of phosphoric and sulfuric acid wereinvestigated. The results showed that the effects of mixed acid was the best. The ompositionof mixed acid as V （H₂SO₄）/V （H₃PO₄） for3/7, and acid concentration of15%. A largenumber of solid phase, alternate accumulation of permeable Ca（H₂PO₄）2and CaSO₄·2H₂Owere obtained due to the application of mixed acids. Existence of Ca（H₂PO₄）2in the solidlayer can promoting the reaction of magnesium removal efficiently and decreased the lossof P₂O₅obviously.The main factors in the process of magnesium impurities removal from phosphate rock（which the content of MgO is about3.0%） by mixture of phosphoric and sulfuric acid werestudied. Under optimized working conditions: pH value of2-3, liquid/silid2cm³/g,temperature50oC, stirring speed200rpm and leaching time30min, the result showed thatcontent of MgO was reduced to less than1.0%. After the leaching process,the CaO/P₂O₅ratio less than1.6and MgO/P₂O₅ratio less than0.08in the solid phase meet therequirements of the phophate industry.The kinetics of magnesium removal from phosphate rock through leaching by mixtureof phosphoric and sulfuric acid was investigated. The results showed that the removal rateof magnesium increased with increasing sulfuric acid in the mixture, acid concentration,liquid/solid ratio, temperature, product of the particle size and MgO content. The kineticacould be described by the unreacted core shrinking model. The apparent activation energyfor this process was found to be move than40.0kJ/mol, so that the rate of magnesium removal was controlled by chemical reaction.更多还原