P 2 O 5 Solubility of Dephosphorization Slag in Citric Acid.

The dephosphorization slag produced by the duplex steelmaking process is suited for making steel slag phosphate fertilizer. The factors influencing P2O5solubility of dephosphorization slag in citric acid were studied and a series of CaO-SiO2-FetO-P2O5quaternary slag samples were prepared and analyzed. It was demonstrated that the corresponding P2O5solubility varies from 81.6% to 97.9%. The P2O5solubility increases with the increase of CaO/SiO2, CaO/P2O5, CaO/(SiO2+P2O5) and SCA (Surplus Calcium Alkalinity), and decreases with the increase of both FetO and P2O5content. Halide content has a notable negative effect on solubility in citric acid. The P2O5solubility decreases from 92.5% to 47.1% with 1.0% CaF2added. When the content of CaF2reaches 6.0%, the solubility of slag is only 13.7%. With 2.0% and 5.0% CaCl2added, the P2O5solubility decreases from 92.5% to 81.9% and 79.8%, respectively. In order to get a higher soluble slag, fluorine-containing and chlorine-containing substances cannot be added into the steelmaking converter. The addition of MgO and MnO has a positive influence on the P2O5solubility in citric acid. The addition of Al2O3shows an opposite influence. Na2O can significantly improve the P2O5solubility in citric acid solution. [ABSTRACT FROM PUBLISHER]