Research on the Solubility of Radioactive Elements in the Ashes from the Soma in Turkey

Abstract

Coal combustion results in wastes such as fly ash, slag, and flue gases. In Turkey, approximately 45 million tons of coals are fired annually and consequently around 20 million tons of fly ashes are produced. Such large volumes of ash pose a significant problem both for society and the environment. Furthermore, significant amounts of uranium and thorium are often encountered in these ashes. These concentrations are relatively higher for ashes from younger age lignites. Within the scope of this study, a series of characterization tests were performed on samples taken from Soma thermal power plant, one of the largest in Turkey. Characterization studies include particle size analysis, moisture analysis, density determination, pH profile measurements, chemical analyses, and mineralogical analyses. Leach tests with sulfuric acid (H2SO4) were then performed. The leaching of the radioactive minerals (uranium and thorium) with the help of sulfuric acid in the ashes was examined and the optimum leaching parameters were investigated. The recovery opportunities of uranium and thorium metals in the ashes were addressed. The results indicated that under optimum conditions, 94.71% uranium dissolution efficiency and 93.21% thorium dissolution efficiency were obtained.