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历来研究磷矿还原机理,都是考虑 Ca_3(PO_4)_2,主要提出以下几种机理:1.Ca_3(PO_4)_2→CaO+P_2O_5,H_2O_5+C→P_2+CO;2.Ca_3(PO_4)_2+C→Ca_3P_2+CO,Ca_3(PO_4)_2+Ca_3P_2→P_2+CaO;3.Ca_3(PO_4)_2+CO→P_2+CaO+CO_2,CO_2+C→CO;4.Ca_3(PO_4)+SiO_2→P_2O_5+CaSiO_3,P_2O_5+C→P_2+CO。但是,这几种机理都没有充分的根据,不能圆满解释实际过程。因为根据文献资料来看,一般认为 Ca_3(PO_4)_2 的分解是不可能的,Ca_3P_2 大概在高于1600℃才能形成,CO 很难还原 Ca_3(PO_4)_2。在磷矿中,磷多以 3Ca_3(PO_4)_2·CaF_2 的形式存在。本工作直接研究原矿的还原,讨论3Ca_3(PO_4)_2·CaF_2 的还原机理,而不是 Ca_3(PO_4)_2。以下三个方面是本工作重点:
Historically, the mechanism of phosphate rock reduction has been studied considering Ca_3 (PO_4) _2. The main mechanisms are as follows: 1.Ca_3 (PO_4) _2 → CaO + P_2O_5, H_2O_5 + C → P_2 + CO; 2.Ca_3 (PO_4) _2 + C → Ca_3P_2 + CO, Ca_3 (PO_4) _2 + Ca_3P_2 → P_2 + CaO; 3.Ca_3 (PO_4) _2 + CO → P_2 + CaO + CO_2, CO_2 + C → CO; 4.Ca_3 (PO_4) + SiO_2 → P_2O_5 + CaSiO_3, P_2O_5 + C → P_2 + CO. However, none of these mechanisms are fully substantiated and can not satisfactorily explain the actual process. Because according to the literature, it is generally considered that the decomposition of Ca_3 (PO_4) _2 is impossible, Ca_3P_2 is probably formed above 1600 ° C, and CO is hard to reduce Ca_3 (PO_4) _2. In phosphate rock, phosphorus mostly exists in the form of 3Ca_3 (PO_4) _2 · CaF_2. This work directly studies the reduction of ore, and discusses the reduction mechanism of 3Ca_3 (PO_4) _2 · CaF_2 instead of Ca_3 (PO_4) _2. The following three aspects are the focus of this work: