Experimental study on phosphorus distribution ratio and capacity of environment-friendly dephosphorization slag for high-phosphorus hot metal pretreatment

摘要

In this investigation, the phosphorus distribution ratios in the CaF_2 system and B_2O_3 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 B_2O_3 slag system is much greater than that of the CaF_2 system. It is demonstrated thatB_2O_3 can completely replace CaF_2 as fluxing agent for high-phosphorus hot metal pretreatment. With CaF_2 as fluxing agent, the phosphorus capacity increases with increasing CaO content in the slag, but the phosphorus distribution ratio decreases. B_2O_3, when used as fluxing agent, can react with high melting point phases such as 2CaOSiO_2 and 3CaOP_2O_5 in the slag to form new phases with low melting points such as 11CaO-B_2O_3.4SiO_2,2CaOB_2O_3.SiO_2,and Ca_(9.93)(P_(5.84)B_(0.16)O_(24)) (B_(0.67)O_(1.79)), thereby acting as a fluxing agent. When the ratio of iv(B_2O_3)/H'(CaO) is 0.16, the phosphorus distribution ratio reaches its maximum value, that is, the dephosphorization ability of the slag is at its maximum.