Recovery of valuable materials from phosphorus slag using nitric acid leaching followed by precipitation method

摘要

PS, the principal waste of phosphorus production, comprises some elements such as Si, Ca, Fe, Al, rare earth metals (REMs), etc. Due to the high annual production volumes of PS, it is discarded in disposal areas, leading to severe environmental pollution and ecosystem damage. Therefore, the most important objective of this work was to present a recovery process for valuable materials including Sigma REMs2O3, SiO2, and Ca(NO3)(2). These materials have a critical role in various industries. In the present study, they were recovered by the leaching process with 8 M nitric acid, the S-to-L phase ratio of 1:3, the contact time of 120 min, and the temperature of 75 degrees C. Afterward, precipitation with oxalic acid and pH adjustment by ammonia were performed. The elemental analysis as well as the structural, morphological, and molecular properties of PS and the extracted products were characterized using ICP-MS, XRD, FESEM, EDS, FT-IR, SAXS, and nitrogen adsorption-desorption measurement. The results indicated that the recovery efficiencies of Sigma REMs2O3, SiO2, and Ca(NO3)(2) from PS were 88.14%, 97.64%, and 92.37%, respectively. Moreover, the purities of Sigma REMs2O3, SiO2, and Ca(NO3)(2) were 99.04%, 99.16%, and 99.03%, respectively.