Abstract

YANG, F.; BI, X.G.  and  ZHOU, J.D.. Experimental study on phosphorus distribution ratio and capacity of environment-friendly dephosphorization slag for high-phosphorus hot metal pretreatment. J. S. Afr. Inst. Min. Metall. [online]. 2016, vol.116, n.6, pp.581-585. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2016/v116n6a14.

In this investigation, the phosphorus distribution ratios in the CaF₂ system and B₂O₃ system dephosphorization slags for high-phosphorus hot metal pretreatment were measured by an indirect method under laboratory conditions. Firstly, the phosphorus distribution ratio between liquid slag and solid iron was measured, and then the phosphorus distribution ratio between liquid slag and hot metal was calculated. Phosphorus capacity was calculated in terms of the composition and optical basicity of the slag. Dephosphorization slag was also studied by scanning electron microscopy, energy dispersive analysis, and X-ray diffraction analysis. The experimental results show that the phosphorus capacity of the B₂O₃ slag system is much greater than that of the CaF₂ system. It is demonstrated thatB₂O₃ can completely replace CaF₂ as fluxing agent for high-phosphorus hot metal pretreatment. With CaF₂ as fluxing agent, the phosphorus capacity increases with increasing CaO content in the slag, but the phosphorus distribution ratio decreases. B₂O₃, when used as fluxing agent, can react with high melting point phases such as 2CaOSiO₂ and 3CaOP₂O₅ in the slag to form new phases with low melting points such as 11CaO-B2O3.4SiO2, 2CaO^O3.SiO2, and Ca_9.93(P_5.84Bo₁₆O₂₄) (B_0.67 O_1.79), thereby acting as a fluxing agent. When the ratio of w(B₂O₃)/w(CaO) is 0.16, the phosphorus distribution ratio reaches its maximum value, that is, the dephosphorization ability of the slag is at its maximum.

Keywords : hot metal pretreatment; dephosphorization; phosphorus distribution ratio; phosphorus capacity.

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