Wet Phosphoric Acid-phosphogypsum Flotation Purification Combined New Process

ObjectiveIn order to improve the production process of wet-process phosphoric acid, shorten the purification process of phosphogypsum, and achieve the harmless treatment of phosphogypsum, the combined purification process of wet-process phosphoric acid and phosphogypsum by flotation was studied. MethodBy the reaction of sulfuric acid and phosphate ore, the leaching behavior of phosphate rock was studied, and the phosphogypsum slurry was studied by reverse flotation process to improve the quality and reduce impurity. ResultWhen the particle size of phosphate ore is less than 178 µm, the stirring speed is 350 r/min, the reaction temperature is 75 ℃, the sulfuric acid concentration is 25%, and the reaction time is 4 h, the decomposition rate of phosphate ore reaches 96.12%.The shrinkage unreacted core model is used to determine the solid film diffusion as the final rate control step. At the conditions of activator dosage 0.18 kg/t, activation time 10 min, self-made complex ether collector dosage 0.36 kg/t and pulp temperature 60 ℃, the flotation concentrate whiteness reaches 65.7% and the purity reaches 96.2%. ConclusionThe contents of water-soluble P₂O₅ and water-soluble F^- meet the requirements of GB/T 23456-2018 first-grade gypsum indexand the quality of phosphoric acid meets HG/T 4068-2008 standard.