Thermodynamic Analysis of Removing Phosphorus from High Phosphorus Oolitic Hematite

Abstract

According to the law of mass balance and charge balance, the lg[P]T-pH diagram of hydroxyapatite in the system of P-Ca-H2O is plotted on the basis of thermodynamic data at 298K and 373K. The thermodynamics condition of hydroxyapatite decomposition is analyzed by thermodynamic equilibrium diagram. The analysis results show that the pH value of solution is a very important factor for the decomposition of hydroxyapatite, and hydroxyapatite can be decomposed on the acid or alkaline condistions. In addition, reaction temperature also has important effect on the hydroxyapatite decomposition. In the acid solution, low reaction temperature can facilitate the decomposition of hydroxyapatite. But in the alkaline conditions, high temperature is beneficial to the decomposition. On the base of thermodynamics analysis results, the verification experiments are carried out on same decomposition conditions. The experimental results accords with the theoretical analysis. The theoretical analysis can guide the research of removing phosphorus from high-phosphorus iron ores.