Abstract
The seepage and diffusion of acid mine drainage (AMD) generated from self-heating coal gangue tailings caused acid pollution to the surrounding soil and groundwater. Red mud derived from the alumina smelting process has a high alkali content. To explore the feasibility of co-disposal of coal gangue and red mud for prevention of AMD, coal gangue and red mud were sampled from Yangquan (Shanxi Province, China), and dynamic leaching tests were carried out through the automatic temperature-controlled leaching system under the conditions of different temperatures, mass ratios, and storage methods. Our findings indicated that the heating temperature had a significant effect on the release characteristics of acidic pollutants derived from coal gangue, and that the fastest rate of acid production corresponding to temperature was 150 °C. The co-disposal dynamic leaching tests indicated that red mud not only significantly alleviated the release of AMD but also that it had a long-term effect on the treatment of acid pollution. The mass ratio and stacking method were selected to be 12:1 (coal gangue: red mud) and one layer was alternated (coal gangue covered with red mud), respectively, to ensure that the acid-base pollution indices of leachate reached the WHO drinking-water quality for long-term discharge. The results of this study provided a theoretical basis and data support for the industrial field application of solid waste co-treatment.
Highlights
Coal gangue is a by-product of coal mining and washing and its discharge amount accounts for approximately 10–15% of total coal production [1,2]
The principal aim of passive treatment is to prevent the acid mine drainage (AMD) produced by the oxidation of pyrite in coal gangue, and it can be obtained by removing sulfide, isolating water and air, directly passivating pyrite, and adding antibacterial agents and alkaline components [36]
Under condition of the fastest fastest release release rate rate of of acidic acidic components in coal gangue, dynamic leaching tests were performed on the co-disposal of red mud and components in coal gangue, dynamic leaching tests were performed on the co-disposal of red mud coal gangue to research the co-disposal effect
Summary
Coal gangue is a by-product of coal mining and washing and its discharge amount accounts for approximately 10–15% of total coal production [1,2]. The active remediation, that is, adding the neutralizer, adsorbents, and sulfate-reducing bacteria into the collected wastewater, both increases the pH value of the wastewater through acid-base neutralization and reduces the content of sulfates by the adsorption and precipitation of heavy metals [23,24,25,26,27,28,29,30,31]. The principal aim of passive treatment is to prevent the AMD produced by the oxidation of pyrite in coal gangue, and it can be obtained by removing sulfide, isolating water and air, directly passivating pyrite, and adding antibacterial agents and alkaline components [36]. Red mud added to prevent acid pollution caused by coal gangue could be a potential method for solid waste’s co-treatment projects. An optimal co-disposal program of red mud and coal gangue was proposed to ensure that water meets the quality standards so that it could be discharged outward
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