Comparative study on the leaching of gallium and phosphorus from phosphorus flue dust

In this work the effect of reaction temperature, sulfuric acid concentration, liquid-to-solid ratio and Fe²⁺ concentration on sulfuric acid leaching of gallium and phosphorus from phosphorus flue dust was studied. The results showed that gallium and phosphorus extraction increased with the increase of temperature, sulfuric acid concentration and liquid-to-solid ratio. Fe²⁺ concentration did not significantly affect the recovery of gallium and phosphorus. Gallium was relatively more difficult to extract than phosphorus, higher reaction temperature, sulfuric acid concentration and liquid-to-solid ratio were required for the leaching of gallium from the flue dust. The acid-soluble gallium and phosphorus could be completely extracted with the leaching solution containing 20% sulfuric acid and 0 to 50 g/L Fe²⁺ at temperature of 80°C, liquid-to-solid ratio of 10:1.