Study On Characteristic And Comprehensive Utilization Strategy Of Coal Gangue In Ordos Mining Area

Coal gangue,as the by-product of coal resources development with huge output,has been the focus of academic research on its environmental effects and comprehensive utilization.In this paper,the coal gangue of a coal mine in Ordos is taken as the research object.The content of heavy metals in coal gangue is analyzed firstly,and the potential ecological risk assessment was carried out.The release pattern of heavy metals under the conditions of soaking and leaching of coal gangue.NaX zeolite based on coal gangue is successfully synthesized by using silicon and aluminum in coal gangue with suitable synthesis conditions without adding extra silicon and aluminum sources.The synthesized products are characterized by XRD,SEM and other methods.The synthetic NaX zeolite is used as adsorbents to adsorb Cd?II?and Cu?II?simulated wastewater.The effects of zeolite dosage,initial pH of wastewater and adsorption temperature on adsorption were studied.The isothermal adsorption model and adsorption kinetic model were fitted and the isothermal adsorption model and adsorption kinetic model are fitted.Firstly,the characteristics of heavy metals in coal gangue are studied.The results show that the comprehensive potential ecological risk of the coal gangue is slight and the release concentration of heavy metals meets the maximum allowable daily emission mass concentration of toxic substances in coal industrial wastewater,which has little risk to the environment and can be put into resource utilization.Subsequently,NaX zeolite is synthesized from coal gangue by alkali fusion method under the conditions of 3.5Na₂O:Al₂O₃:2.9SiO₂:150H₂O,aging time of 6 hours,crystallization temperature of 100?and crystallization time of 12 hours.The formation of NaX zeolite is confirmed by XRD,FTIR and SEM results.The BET test results show that the product molecular sieves have large specific surface area and pore volume.At last,NaX zeolite is used as adsorbent in the adsorption experiments.The results show that the adsorption capacity of Cd?II?and Cu?II?on NaX zeolite is more consistent with Langmuir isothermal adsorption model,and the maximum adsorption capacity is 100.11 and95.29 mg·g^-1,respectively.The adsorption process is more in line with the pseudo-second-order kinetic model.The fitting results of W-M model show that the adsorption rate is controlled by both external diffusion and intraparticle diffusion.The study in the paper shows that the risk of heavy metal pollution of coal gangue in this area is slight and can be put into resource utilization.The NaX zeolite synthesized from coal gangue has good adsorption capacity for heavy metals.The synthesis of zeolite from coal gangue can be an effective complement to the comprehensive utilization strategy of coal gangue.