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The hold‐up of molten pig iron and slag melt in the coke packed bed of blast furnace (BF) causes a decrease of void between coke lumps and inhibits gas permeability. Smooth dripping of those liquids in the coke bed is desirable to keep the productivity of BF. Herein, the conditions for smooth flowing of molten iron on coke surface are calrified, and the falling angles of Fe‐C and actual pig iron droplets on coke and graphite are measured at high temperature. It is found that Fe‐C droplet easily slids down on coke because of small falling angle, and the falling angle of actual pig iron is even smaller, while those droplets adhere to a graphite substrate. The carbon in iron has only a small effect on the static contact angle with coke, but has a great influence on the falling angle. From the viewpoint of the roughness of coke surface, the variation of static contact angle and falling angle is discussed. [ABSTRACT FROM AUTHOR]

Steelmaking slag is considered an attractive phosphorus secondary resource since it contains relatively high phosphorus content and a fairly fixed composition with the negligibly small hazardous element. The carbothermic reductions of CaO–SiO2–FeO–P2O5 slags were carried out to investigate the reduction behavior of phosphorus from steelmaking slags. During the carbothermic reduction process of the slags, iron oxides and phosphorus oxides were reduced to metallic iron and phosphorus gases. The generated phosphorus gases dissolved into the reduced iron, and some escaped into the gas phase. The phosphorus content in the reduced iron increased until Fe2P is formed but could not dissolve anymore. It was found that the amount of phosphorus dissolution into the reduced iron and that escaped into the gas phase was comparable. The phosphorus content in the reduced iron is possibly determined by the balance between the carbon and phosphorus dissolution rates into the reduced iron. In other words, the phosphorus content in the reduced iron was determined by kinetics but not thermodynamics. The findings in the present study indicate that the carbothermic reduction of 2CaO·SiO2–3CaO·P2O5 solid solution separated from steelmaking slags will be the plausible approach to recover phosphorus from steelmaking slags. [ABSTRACT FROM AUTHOR]

The crystallography of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization slag in current steelmaking process was determined in this study. Understanding the physical and chemical properties of these Ca2SiO4-Ca3P2O8 solid solutions is a preliminary step towards understanding the role of the Ca2SiO4-Ca3P2O8 solid solutions in the dephosphorization process. The range of Ca3P2O8 in the Ca2SiO4-Ca3P2O8 solid solutions synthesized for analysis varied from 10 to 90 mol pct, with an incremental increase of 10 mol pct per solid solution. In solid solutions with a Ca3P2O8 content of up to 40 mol pct, the crystal structure at 1773 K was found to be hexagonal, while the solid solutions with a Ca3P2O8 content over 70 mol pct had a trigonal structure. The silicocarnotite solid solutions observed when the Ca3P2O8 content was 50 to 60 mol pct were likely formed by phase transformation during cooling. In the stable solid solution with a Ca3P2O8 content of 50 to 60 mol pct at 1773 K before the occurrence of transformation, the crystal structure is trigonal since it is in the Ca3P2O8-rich range. A linear increase in the lattice parameters c of the solid solutions in the range of (0, 40 mol pct) and (70 mol pct, 100 mol pct) was found with increasing Ca3P2O8 content. The lattice parameter a, however, was almost independent of the Ca3P2O8 content in the solid solutions. [ABSTRACT FROM AUTHOR]