Extraction and transformation of elements in phosphogypsum by electrokinetics

Abstract

Phosphogypsum (PG), as a typical industrial solid waste produced in the wet production process of phosphoric acid, is harmful to the environment and difficult to utilize. In order to explore the migration behavior of impurities in PG under electrokinetic treatment and provide a new treatment technology for the purification and harmless treatment, this paper studied the distribution of soluble impurities (PO43−, F−, Sr, Pb, Cr, Cu, and Mn) in PG under different electrokinetic treatment conditions. The results indicated that most of water-soluble impurities demonstrated obvious migration distribution laws at different voltages. Under the influence of electroosmotic flow, F− accumulated continually at the cathode. Positive MF+ was produced in acidic circumstances by combining F− and metal ions and travelled to the cathode under the combined action of electric field force and electroosmotic flow. Under electrokinetic treatment, the concentration of PO43− in the anode chamber increased while that of in the cathode chamber decreased. A large number of anions in PG were attached to the anode by coulomb force, reducing the potential. PO43− was s largely enriched in the anode chamber, which is controlled by the free diffusion effect of ions. Heavy metals exhibited higher leaching efficiency under anodic acid conditions. With the increase of applied voltage, the concentration of heavy metals in the anode chamber gradually increased, which was related to the activity of solution, pH and other factors. The above results indicate that electrokinetic treatment is a novel and efficient PG treatment technology, which has a broad application prospect in impurity removal and PG resource recovery.