【作者】 杨宏辉； 李春； 梁斌； 吴潘； 邱礼有； 吕莉；

【Author】 Yang Honghui Li Chun Liang Bin Wu Pan Qiu Liyou Lv Li (School of Chemical Engineering,Sichuan University,Chengdu,Sichuan 610065,China)

【机构】 四川大学化工学院；

【摘要】 对回转窑中球团内外的反应进行了系统的热力学分析与工艺研究。结果表明,多硅配料磷矿起始还原温度为1417K,较多钙配料低211.6K。球团中炭烧损和磷矿吸收P2O5(称为P2O5反吸)主要发生在球团预热阶段。炭烧损主要源于窑气中残余氧气对炭的氧化,而布多尔反应的影响很小;反吸生成了焦磷酸钙和低熔点的偏磷酸钙(Ca(PO3)2)。窑气中O2、CO2、H2O和P2O5均能氧化磷蒸汽,其反应热力学趋势为O2>P2O5>CO2≈H2O。在现有窑法磷酸工况下回转窑内P2O5不能生成磷酸,偏磷酸的出现可能是P2O5直接水合形成。更多还原

【Abstract】 A systematic thermodynamic analysis and process study of the reactions occurred in and out of the pellets in rotary kiln was conducted.The results show that with more silica feed the initial reduction temperature of phosphate ore in the pellets is 1417K,which is lower than that with more lime feed by 211.6K.The carbon burning and reaction of P2O5 with phosphate ore(the so-called P2O5 back absorption)take place mainly during the preheating stage of pellets.The carbon burning is primarily due to oxidation of carbon by the residual O2 instead of carbon dioxide present in the kiln gases.The back absorption mainly forms Ca2P2O7 and low melting point Ca(PO3)2.The gaseous phosphorus can be oxidized by O2、CO2、H2O or P2O5 in the kiln gases,and their reaction tendency is O2>P2O5>CO2≈H2O.Under the present klin phosphoric acid process conditions,the gaseous P2O5 can not form phosphoric acid in the rotary kiln,thus the metaphosphoric acid being formed is probably by direct hydration of P2O5.更多还原