Treatment of Syrian Phosphogypsum using Acids and Bases

Abstract

Phosphogypsum is a technologically enhanced naturally occurring radioactive material (TE-NORM) that contains radionuclides from ²³⁸U and ²³²Th decay series which are of most radio-toxicity. The reduction in concentration of radionuclides content from PG was based on leaching of ²²⁶Ra, ²¹⁰Pb, U and ⁴⁰K using different chemicals.The factors which affect the leaching process such as leaching reagent, concentration of the proposed reagent, liquid-solid ratio, contact time, temperature and multi leaching effect were optimized. Based on the experimental results, about 79.4%, 57.9%, 65.7% and 89.8% of U, ²²⁶Ra, ²¹⁰Pb and ⁴⁰K respectively, were successfully removed from the PG under optimum conditions ( HNO₃, concentration (4M), liquid-solid ratio mL-gr(1-1), contact time (2h), temperature (60°C) and three leaching steps). Using this treatment of PG waste leads to obtain a decontaminated product that can be safely used in many industrial applications.

Keywords: Phosphogypsum waste, Leaching process, Radioactive materials, TENORM.