Abstract
In order to effect enrichment of phosphorus in the converter slag, phosphorus enrichment was researched by slag modification with SiO2. The SiO2 modification process was evaluated thermodynamically, and phosphorus rich phase was separated from experimental slag by magnetic separation. The results show that n2CaO.SiO2–3CaO.P2O5 (nC2S–C3P) solid solution is generated by the reaction of Ca3(PO4)2 phase in the slag with precipitated Ca2SiO4 phase at 1623 K, and Ca2SiO4 in the solid solution is reduced with increasing SiO2; hence, the phosphorus content in the solid solution is increased. If the addition of SiO2 is excessive, the amount of Ca2SiO4 precipitation in the slag is decreased remarkably (and even disappeared), CaSiO3 phase is generated and the generation of nC2S–C3P solid solution is reduced, which is not favourable to phosphorus enrichment. Through magnetic separation, the non-magnetic fraction was increased by 10–74·68% compared with the original slag. The distribution ratio of P2O5 was increased from 2·71 to 5·48. As 84·57% of the phosphorus in the slag is in the collected non-magnetic substances, the work demonstrates that most of the phosphorus is able to be effectively recycled.
Published Version
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