The Solubilityof Phosphogypsum and Recovery ofHeavy and Radioactive Elements

Abstract

The essential purpose of this paper is to illustrate and inspect the leaching characteristics of Iraqi Phosphogypsum (PG). The paper presents the results of the dissolution characteristics of heavy and radioactive elements from PG, which is a by-product result from the industry of phosphate fertilizers. Leachability of heavy and radioactive elements in deionizedwater that has been inspectedunder various states of leaching, including solid/liquid ratio (10, 20and 50 /1g/L) and temperatures (25, 45and 85 °C), with constant other parameters such as string speed (300 rpm) and contact time (60 minutes). For the most analysis elements, the progressiverelease of the metals, in addition to the majorelements reflects high mobility. The mobility of trace metals in PG has been generally classifiedinto three main degrees: (1) high mobility elements such as Pb, Zn,Mn, and Cr; (2) moderate mobility elements such as Sr, V, Ba,Y,Hg,K and Ni; and (3)low mobility elements like Ca,Cu,Fe, and Ag. The maximum concentrations of the most ofthe metals were attainedfrom a leaching state of 10/1g/L. Regardingtemperature, the experimental results revealed that the PG solubility to leaching out elements increases noticeably as the applied temperature ranges from 25 to 45°C; after this degree,the leaching efficiency decreases. Chloride had a positive and negative effect on the solubility of phosphorus. Calcium chloride had an adverse effect onsolubility and observed reduced solubility with increased chloride. While the positive effect of sodium and magnesium chloride was observed, the solubility ratio increased with the increase of chlorides. However, theeffect of magnesium chloride was highercompared to the sodium chloride one.