Study on remediation effect of radioactive-heavy metal contaminated soil in stone coal mines by chemical elution

Stone coal contains a relatively high content of natural radionuclides. Its development and utilization will cause radioactive pollution and associated heavy metal pollution to the environment. In recent years, the development and utilization of stone coal has caused radioactive pollution and heavy metal pollution to the environment. More and more public attention has been paid to Jiangxi. As one of the provinces with the most abundant stone coal reserves in the country, most stone coal mines are open-pit mining. The long-term rainwater leaching and surface runoff of abandoned mines have caused serious damage to the surrounding soil environment. In order to study the remediation technology of the radioactive and heavy metal compound contaminated soil around the stone coal mine area, the vibration leaching method was used to conduct the indoor test. According to the soil test results collected on site in a stone coal mine area in Jiangxi Province, the main pollutant indexes were radionuclide uranium and heavy metal zinc and cadmium. According to previous studies, in view of its unique radioactive and heavy metal compound pollution characteristics,hydrochloric acid, citric acid, oxalic acid, EDTA and ferric trichloride were selected as eluents, and the better leaching conditions were determined by controlling leaching concentration and mixed leaching. The results show that in eluents the best comprehensive decontamination effects on compound polluted soil were oxalic acid, hydrochloric acid and ferric trichloride. The best leaching rates under different concentration gradients were 1 mol/L oxalic acid and 1 mol/L hydrochloric acid solution, and the elution effect of combined eluent was improved to some extent compared with a single eluent. The leaching rate of U, Cd and Zn with the mixture of 1 mol/L oxalic acid solution and 1 mol/L hydrochloric acid solution was the highest achieved 99.2%, 97.8% and 43.7%. The research results can be used for the small-scale trial of on-site leaching of remediation of compound contaminated soil, and the potential environmental risks of the soil after leaching and remediation still need to be considered.