Al 2 O 3 and high Al 2 O 3 content composite oxides are the main types of inclusions in aluminium killed bearing steel, and these also have the most significant impact on rolling contact fatigue (RCF) life. The calculation results in the phase diagram by using the FactSage showed that the activity of Al 2 O 3 reached the minimum with the slag composition in a low melting point area at a MgO content less than 5%; a basicity of 5 to 8 and a ratio of CaO/Al 2 O 3 of 1?5 to 2?0 in slag. This slag was most effective in improving the absorption ability of slag for inclusions in bearing steel. By using the experimental slag, the total oxygen could be reduced to 7-10 ppm at Hangzhou Iron and Steel Group Company (HIRGC).

In order to effect enrichment of phosphorus in converter slag, phosphorus enrichment was researched by Al 2 O 3 melting modification, the Al 2 O 3 modification process is discussed according to the thermodynamic analysis, and phosphorus rich phase was separated from experimental slag by magnetic separation. The results show that gehlenite (Ca 2 Al 2 SiO 7 ) and high phosphorus solid solution (n9C 2 S-C 3 P) are generated by the continuous reaction of n2CaO.SiO 2 -3CaO.P 2 O 5 (nC 2 S-C 3 P) solid solution precipitated in the slag with Al 2 O 3 at 1623K. The early precipitated solid solution (nC 2 S-C 3 P) is reduced with increasing content of Al 2 O 3 , and even disappeared. If the addition of Al 2 O 3 is increased or excess in the slag, the high phosphorus solid solution (n9C 2 S-C 3 P) that was generated by the above mentioned reaction will continue to react with Al 2 O 3 to produce gehlenite, then the phosphorus content in the phosphorus rich phase is increased. Through magnetic separation the amount of non-magnetic substance of no. 2 slag after modification is raised 26?88% compared to the original slag, the distribution ratio of P 2 O 5 is raised from 0?96 to 4?61, and the amount of separated non-magnetic substance is 68?47% of the total no. 2 slag, 84?57% of the phosphorus in slag is entered into collected non-magnetic substance, thereby most phosphorus element was recycled.

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