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磷硫混酸脱除磷矿中镁杂质的动力学研究

Kinetics Study of Magnesium Impurity Removal from Phosphate Rock by Mixture of Phosphoric and Sulfuric Acid

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【作者】 陈宇金梦圆王晔王琪崔鹏刘荣沈浩

【Author】 Chen Yu;Jin Mengyuan;Wang Ye;Wang Qi;Cui Peng;Liu Rong;Shen Hao;Anhui Key Laboratory of Controllable Chemical Reaction & Material Chemical Engineering,School of Chemical Engineering,Hefei University of Technology;Anhui Liuguo Chemical Industry Corporation,LTD;

【机构】 合肥工业大学化工学院可控化学与材料化工安徽省重点实验室安徽六国化工有限公司

【摘要】 为了提高磷矿脱镁过程的效率,对磷硫混酸选择性脱除磷矿中镁杂质的过程进行了研究。采用扫描电镜、能谱分析及X射线衍射等方法对反应过程的产物进行了微观分析,并通过实验,利用动力学经验模型进行动力学分析,推导磷硫混酸脱镁反应机理。研究表明,脱镁反应的表观活化能为41.78 kJ/mol,属于化学反应控制。在脱镁过程中,CaCO3·MgCO3与Ca5(PO43F均先与H3PO4反应,反应生成产物Ca(H2PO42再与H2SO4反应;且由于反应体系中磷酸的大量存在,生成了大量可透性的Ca(H2PO42,并促使CaSO4·2H2O由原来的针状、细长瓦楞状或片状变为棒状或斜六面体状,两种晶体交替堆积,在Ca(H2PO42酸解与析出的动态变化中,增加了矿石表面固相附着层的可透性,在促进脱镁反应的同时,抑制了固相中的磷损失,增加了固相中磷的有效利用率。

【Abstract】 For increasing efficiency of MgO removal,the process of remove magnesium impurities from phosphate rock by the mixture of phosphoric and sulfuric acid was investigated to understand the reaction mechanism of magnesium removal via the mixed acid.Scanning electronic microscopy and energy dispersive X-ray spectroscopy were utilized to characterize the intermediate and final products.And semi-empirical model was suggested to analyze the experimental data.It was found that the ratio of magnesium removal was controlled by the chemical reaction step.The apparent activation energy for this process was found to be 41.78 kJ/mol.It also turned out that both CaCO3·MgCO3 and Ca5(PO43F in phosphate ore first reacted with H3PO4,then the generated product Ca(H2PO42 reacted further with H2SO4.A large number of solid phase,alternate accumulation of permeable Ca(H2PO42 and CaSO4-2H2O were obtained due to the application of mixed acids.Existence of Ca(H2PO42 in the solid layer can change the shape of CaSO4-2H2O from needle-like,long and thin corrugated shape,or sheet structure into rod-like shape or rhombohedron shape,reducing the diffusion resistance of ore surface for H+ permeation and promoting the reaction of magnesium removal efficiently.At the same time,the loss of P2O5 was decreased obviously using the mixed acids.

【基金】 安徽省科技攻关项目(1106b0105073)
  • 【文献出处】 化学反应工程与工艺 ,Chemical Reaction Engineering and Technology , 编辑部邮箱 ,2013年04期
  • 【分类号】TQ126.3
  • 【被引频次】6
  • 【下载频次】97
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