| Abstract [eng] |
The purpose of this master’s final degree project was to determine the conditions at the hydrothermal environment of purification of element sulfur from its waste and sulfur conversion to soluble compounds. During experiments the aim was to investigate the chemical / mineral composition of the waste composed in sulfuric acid production during the filtration of molten sulfur, to apply hydrothermal treatment for purification of sulfur waste, to determine the effective conditions for mentioned process in 120–200 °C temperature range and to propose the principal technological scheme of sulfur waste purification. Furthermore, it was aimed to investigate the possibilities and reaction mechanism of sulfur waste conversion to soluble compounds during hydrothermal synthesis and confirm hypothesis by thermodynamic calculations. During the experiments the developed method of chemical analysis was applied for identifying sulfur compounds in liquid medium. Furthermore, the instrumental analysis methods such as XRD, XRF, STA, SEM were also applied. In this master’s final degree project, it was identified that the sulfur waste mainly consisted of orthorhombic system sulfur and quartz. Moreover, it was established that the hydrothermal treatment could be effectively used to purify sulfur waste. It was determined that after hydrothermal treatment and rapid cooling of suspension, by varying water and solid material mass ratio from 3 to 10 and in 120–200 °C temperature, the fraction of particles bigger than 1000 μm size consisted of orthorhombic sulfur. According to the established optimal conditions of sulfur waste sample treatment, by using the proposed industrial technology of sulfur waste purification, 444,8 t of elemental sulfur could be purified every year. Moreover, according to thermodynamic calculations and performed chemical analysis, the sulfate, thiosulfate and sulfide anions were formed in liquid medium during hydrothermal treatment of sulfur waste. The highest achieved sulfur conversion rate to soluble compounds was 51.8 %. |
