QQ客服 官方微博 反馈留言

题名	磷矿还原机理研究
作者	张进荣
学位类别	硕士
答辩日期	1984-06-30
授予单位	中国科学院研究生院
导师	袁孝惇
中文摘要	关于磷酸钙的还原机理至今还没有一致的结论，而磷矿的还原过程尤其没有定论。我国磷矿贮量丰富，但磷肥生产远远不能满足国民经济需要。现在高炉炼磷的重要性越来越被人们认识到，研究磷矿的还原过程很有现实意义。本实验主要研究了英坪、开原、永济三种磷矿的还原过程。通过分析气体成份，物相鉴定，分析残渣五氧化二磷，还有过程中重量变化，基本搞清了一氧化碳还原磷矿的可能性，碳还原过程还原反应的级数，过程中物相的变化，在此基础上提出了可能的还原机理。结果表明一氧化碳可以还原磷矿，有好的扩散条件可达显著的速度。通过分析气象成份，求出了还原3Ca_3(PO_4)_2·CaF_2在1437、1481、1545（°K）下的平衡常数，并进而求得反应的自由能变化：ΔG°＝300600－172.6T（卡）。在纯一氧化碳中还原焙烧过的永济矿在1200 ℃最高可达20％的还原率。由X－ray分析和差热分析表明，在高温下和还原过程3Ca_3·(PO_4)_2CaF_2是很稳定的一个相，它既不能分解，也很少相变，只是和矿中的Fe, Mn等发生少量固熔作用；在二氧化硅存在下，渣的主要相为Ca_2SiO_2F_2；而对于Ca_5(PO_4)_3(OH)的还原过程，则有Ca_4P_2O_9, Ca_2P_2O_7, CaO, C_3P等主要相。对3Ca_3(PO_4)_2·CaF_2用C还原估计有下述两种可能：I: 3Ca_3(PO_4)_2·CaF_2 + Fe, Mn → (Fe, Mn, Ca)_X(PO_4)_y (1) 3Ca_3(PO_4)_2·CaF_2 + C → P_2+CO+CaO+CaF_2 (2) II: 3Ce_3(PO_4)_2·CaF_2+C <-> Ca_3P_2+CO+CaF_2 (1) 3Ca_3(PO_4)_2·CaF_2+C <-> CaC_2+CO+CaF_2+P_2 (2) Ca_3P_2+C <-> CaC_2+P_2 (3) Ca_3P_2+3Ca_3(PO_4)_2·CaF_2 → P_2+CaO+CaF_2 (4) CaC_2+3Ca_3(PO_4)_2·CaF_2 → P_2+CaO+CO+CaF_2 (5) 其中(1)、(2)为控制步骤，(4)、(5)进行相当快，Ca_3P_2和CaC_2的形成起自动催化作用。对Ca_3(PO_4)_2 的还原，高温和较你温有所不同，高温时(1568℃)有：I：Ca_3P_2O_8+C → CaO+P_2+CO (1) CaO+Ca_3P_2O_8 <-> Ca_4P_2O_9 (2) Ca_4P_2O_9+C → CaO+P_2+CO (3) 反应(1)为限制环节，由于(3)进行快，Ca_4P_2O_9的形成将促进还原的进行。在较低温度时(1468℃)II: Ca_3P_2O_8+C → P_2+CaO+CO (1) Ca_3P_2O_8+O_2+P_2 <-> Ca_2P_2O_7 (2) Ca_3P_2O_8 <-> CaO+Ca_2P_2O_7 (3) Ca_2P_2O_7+C → CaO+CO+P_2 (4) 矿石中磷是以3 Ca_3(PO_4)_2CaF_2存在，可见以Ca_3(PO_4)_2来讨论磷矿的还原是不合理的。用碳还原磷矿无论以还原率考虑还是以失重率考虑，还原过程表现为零级反应；对英坪、永济、开阳三种矿还原反应的表现活化能分别是54000、45600、41000（卡）。
英文摘要	Production of phosphorus by blast furnace are both suitable and needful in our country. Unfortunate is that the mechanism of the reduction of phosphate is still not well reserched. Attention was paid in this work on the nation-abundant deposits, considering that most delivered papers about this subject were based on tricalcium phosphate, novertheless phosphorus is found in form of flourapatite in at most all natural minerals. Two kinds of reducing agent were used. Experiments indicated that reduction of phosphate rock by carbonmonoxide could reach a marked rate if good diffusion condition is maintained. By analysis of gaseous concentration the equilibrium constant of following reaction 3Ca_3(PO_4)_2·CaF_2+15CO=3P_2+15CO_2+9CaO+CaF_2 was 958-11E, 264-9Eand 155-7E corresponding to 1437, 1481 and 1545 (~Ok), and by means of Freeenergy-Function method, its other thermodynamic properties was calculated. X- ray analysis showed that in the course of the reduction 3Ca_3(PO_4)_2·CaF_2 is very stable, it neither decomposes nor becomes other phase, while Ca_3(PO_4)_2 has different beheaviors, It would transform to Ca_2P_2O_7 and / or Ca_4P_2O_9, the amount of which depends on conditions, primaryly on temperature and composition. For Ca_3P_2O_8 the mechanism of reduction is as following: Ca_3P_2O_8 + C → CaO + P_2 + CO (1) I: CaO + Ca_3P_2O_8 → Ca_4P_2O_9 (2) at 1568~OC Ca_4P_2O_9 + C → CaO + P_2 + CO (3). Controlling step is reaction (1), reaction (2) proceed at considerably high rate, and reaction (3) goes more faster than (1), so the formation of Ca_4P_2O_9 promotes the reduction; Ca_3P_2O_8 + C <-> CaO + P_2 + CO (1) Ca_3P_2O_8 <-> CaO + Ca_2P_2O_7 (2) II: at 1468(~OC) Ca_3P_2O_8 + O_2 + P_2 <-> Ca_2P_2O_7 (3) Ca_2P_2O_7 + C → CaO + CO (4) For 3Ca_3(PO_4)_2·CaF_2, the mechanism may be: 3Ca_3(PO_4)·CaF_2 + (Fe, Mn,…) → (Fe, Mn, Ca,…)_x(PO_4)_y + CaF_2 I: 3Ca_3(PO_4)_2·CaF_2 (1) + C → P_2+CO + CaO + CaF_2 (2) (Fe,Mn,Ca,…)_x(PO_4)_y + C → P_2 + CO +(CaO,MnO,…)(3) 3Ca_3(PO_4)_2·CaF_2 + C <-> Ca_3P-2 + CO + CaF_2 (1)3Ca_3(PO_4)_2·CaF_2+ <-> CaC_2 + CO + CaF_2 + P_2 (2) II: Ca_3P_2 + C <-> CaC_2 + P_2 (3) Ca_3P_2 + 3Ca_3(PO_4)_2·CaF_2 → P_2 + CaO + CaF_2 (4) CaC_2+3Ca_3(PO_4)_2·CaF_2 → P_2+CaO+CO+CaF_2 (5) Reaction (1) and (2) are limiting steps of the course. When SiO_2 was added following reactions took place: CaO + SiO_2 + CaF_2 → Ca_2SiO_2F_2 CaO + SiO_2 → CaSiO_3 CaF_2 + SiO_2 → SiF_4 + CaO CaF_2 + H_2O → HF + CaO.
语种	中文
公开日期	2013-09-28
页码	73
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/2085]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	张进荣. 磷矿还原机理研究[D]. 中国科学院研究生院. 1984.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。