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磷矿的碳还原
刘明
Subtype硕士
Thesis Advisor萧骅昭
1989-06-30
Degree Grantor中国科学院研究生院
Abstract本工作对磷矿的碳还原作了较为系统的研究。热力学计算表明,以下反应从化学热力学角度是无法进行的:2Ca_3(PO_4)_2 = 6CaO + P_4O_(10) 2Ca_3(PO_4)_2 + 6SiO_2 = 6CaO·SiO_2 + P_4O_(10) 2Ca_3(PO_4)_2 + 6Al_2O_3 = 6CaO·Al_2O_3 + P_4O_(10) Ca_3(PO_4)_2 + 5CO = 3CaO + 5CO_2 + P_2 2Ca_(10)(PO_4)_6F_2 = 3Ca_3(PO_4)_2 + CaF_2 2Ca_(10)(PO_4)_6F_2 = 18CaO + 3P_4O_(10) + 2CaF_2 2Ca_(10)(PO_4)_6F_2 = 18SiO_2 = 18CaO·SiO_2 + 3P_4O_(10) + 2CaF_2 2Ca_(10)(PO_4)_6F_2 + 18Al_2O_3 = 18CaO·Al_2O_3 + 3P_4O_(10) + 2CaF_2 Ca_(10)(PO_4)_6 + 15CO = 9CaO + 15CO_2 + 3P_2 + CaF_2 当存在SiO_2和在较高的温度及较低的CO_2和P_2分压条件下,CO还原Ca_3(PO_4)_2和Ca_(10)(PO_4)_6F_2的反应是可能的,但它不是还原反应的主流。降低环境中P_2和CO的分压,有助于碳还原Ca_3(PO_4)_2和Ca_(10)(PO_4)_6F_2反应的平衡温度的降低。实验结果否定了固体氟磷灰石热分解的可能性,同时表明在1500 ℃ 以上的温度下,Si~(4+)可以取代氟磷灰石中P~(5+)的晶格位置,而Al~(3+)则不能。这个现象可从晶体化学上得以解释。根据X-射线衍射分析和显微物相分析的结果,作者确定了反应产物的物相组成和变化,并用相图作了解释。另外,根据还原失重计算了还原率、比较了不同条件下反应的活化能。最后作者提出固体碳直接还原氟磷灰石的机理,并指出了反应的控制步骤,认为大量熔体产生造成碳的过早熔离不利于还原反应的进行。
Other AbstractInvestigations have been systematically made on the reduction of phosphate are by carbon. Thermodynamical calculations show that the following reactions cannot proceed according to chemical thermodynamics: 2Ca_3(PO_4)_2 = 6CaO + P_4O_(10) 2Ca_3(PO_4)_2 + 6SiO_2 = 6CaO·SiO_2 + P_4O_(10) 2Ca_3(PO_4)_2 + 6Al_2O_3 = 6CaO·Al_2O_3 + P_4O_(10) Ca_3(PO_4)_2 + 5CO = 3CaO + 5CO_2 + P_2 2Ca_(10)(PO_4)_6F_2 = 3Ca_3(PO_4)_2 + CaF_2 2Ca_(10)(PO_4)_6F_2 = 18CaO + 3P_4O_(10) + 2CaF_2 2Ca_(10)(PO_4)_6F_2 = 18SiO_2 = 18CaO·SiO_2 + 3P_4O_(10) + 2CaF_2 2Ca_(10)(PO_4)_6F_2 + 18Al_2O_3 = 18CaO·Al_2O_3 + 3P_4O_(10) + 2CaF_2 Ca_(10)(PO_4)_6 + 15CO = 9CaO + 15CO_2 + 3P_2 + CaF_2 Under the circumstance of high temperature, low pressures of CO_2 and P_2 and in the existence of SiO_2, it is possible for CO to reduce Ca_3(PO_4)_2 and Ca_(10)(PO_4)_6F_2. But this process is not essential to the reduction of phosphate ore. The equilibrium temperature of reduction of Ca_3(PO_4)_2 and Ca_(10)(PO_4)_6F_2 can decrease while decreasing the pressures of CO and P_2. Experiments indicate that there is no possibility of thermo-decomposition of solid fluorapatite and when the temperature is higher than 1500 ℃, Si~(4+) can substitute P~(5+) in the crystal lattice of fluorapatite but Al~(3+) cannot. This phenomenon can be explained by crystal chemistry. By means of X-ray diffractions and microanalyses, the compositions and changes of phases of reaction products have been determined and explained by phase diagrams. With the decrease of gravity after the reaction, the fractions of reduction were calculated, then the reaction rates under different circumstances compared, the kinetic equations established and activation energies calculated. At last, the mechanism of direct reduction of fluorapatite by solid carbon and the control steps were proposed. It is thought that the presence of lots of melts can lead to the early seperation of carbon which is not beneficial to the reduction.
Pages77
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8387
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
刘明. 磷矿的碳还原[D]. 中国科学院研究生院,1989.
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