Acidolysis kinetics and RE leaching mechanisms of RE-bearing phosphorite ores

The kinetics behaviors and leaching mechanisms of rare earths by acidolysis were studied for Zhijin Xinhua phosphorite ores. It is shown that the ∑REO conversion ratio increases with increasing temperature and sulfuric acid concentration in the reacting solution, which is similar to the kinetics process of P₂O₅. The acidolysis kinetics of ∑REO reveals that the Drozdov equation can describe the dissolution progress of the ores quite well. The correlation coefficient fitting experimental data is more than 0. 99. The reaction apparent activation energy of P₂O₅ calculated by the Arrhenius equation indicates that the main reaction of Zhijin Xinhua phosphorire ores dissolved by sulfuric acid is a solid-film diffusion control process, as well as for ∑ REO because of its special presentation in the form of ions in the lattices of collophanite. In addition, studies on the leaching mechanisms of ∑REO dissolved by sulfuric acid show that RE₂(SO₄)₃ is the main existence state in the solution, while RE₂(SO₄)₃ and rare earths enwrapped by calcium sulphate crystals are the main existence state in phosphogypsum.