Desilicification Reclying Ferrophosphorus Slag under Vacuum

Abstract

This is an article in the field of metallurgical engineering. For recycling theferrophosphorus slag which a by-products of phosphorus chemical industry,the thermodynamic calculations and experimentally investigations of the removal of SiO2 by added CaO were carried out. The results of thermodynamic calculations of the reaction between SiO2 and CaO show that: the Gibbs free energy values of generating CaO·SiO2, 2CaO·SiO2, 3CaO·SiO2 and 3CaO·2SiO2 are less than zero, when the temperature in 900～1700 K range and molar ratio of(SiO2∶CaO)= 1∶1～3. It is feasible to generate calcium silicate by adding CaO, which can be used as a method of desilicification for ferrophosphorus slag. The experimental results show that:there are two layers of the products,i.e. Ca2SiO4, Ca3SiO5in the upper layer and Fe2P in the lower layer when the pressure between 10～40 Pa and the temperature 1573 K and molar ratio of SiO2∶CaO = 1∶1. The final products were testified to be ω（Si）<0.07%, which can be served as the precursor of transition metal phosphide and the potential feasibility of ferrophosphorus recycling.

Keywords

• metallurgical engineering
• ferrophosphorus
• desilicification
• metal phosphide
• vacuum