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 SiO
2 by added CaO were carried out. The results of thermodynamic calculations of the reaction between SiO
2 and CaO show that: the Gibbs free energy values of generating CaO·SiO
2, 2CaO·SiO
2, 3CaO·SiO
2 and 3CaO·2SiO
2 are less than zero, when the temperature in 900~1700 K range and molar ratio of(SiO
2∶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. Ca
2SiO
4, Ca
3SiO
5in the upper layer and Fe
2P in the lower layer when the pressure between 10~40 Pa and the temperature 1573 K and molar ratio of SiO
2∶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.