Departmental Bulletin Paper マルチフェイズフォーメーションによるリン資源の高効率回収法の要素研究(学内特別研究および国外研修,学内特別研究費報告書)

内田, 祐一  ,  Yu-ichi, Uchida

Steelmaking Slag is a promising resource of phosphorus though it is utilized as a landfill or road construction materials in common. Phosphorus-concentrated phase (P-phase) in steelmaking Slag is [2CaO・SiO2-3CaO・P2O5] solid solution. Aiming to obtain an extensive information on P-phase, laboratory experiments were carried out for relatively lower basicity (mass%CaO/mass%SiO2) slag compared to previous works. The slag sample was prepared by mixing reagents and heating them to 1573K in a resistance furnace. EPMA observation of the slag showed different mineral phases corresponding to the slag basicity ranging from 0.87 to 1.6. When the slag basicity was 1.2 and 1.6, P-phase was observed. The phosphorus content of P-phase in the slag with basicity of 1.2 is higher than that in the slag with basicity of 1.6. No P-phase is observed in the slag with basicity of 0.87 and phosphorus was distributed through liquidus matrix. Based on a thermochemical consideration with the phase diagram of the [CaO-SiO2- P2O5] system, lowering the slag basicity to CaO・SiO2 saturation would come to coexistence of a higher P-phase such as 5CaO・SiO2・P2O5.This would possibly lead to an effective phosphorus recovery from steelmaking slag.

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