Effect of Coal Gangue Particle Size on Its Leaching Characteristics

Coal gangue is the largest residues produced during the mineral processing phase of coal mining. Owing to their ever-increasing production, coal gangue utilization is a matter of great concern due to the carbon emissions and costs associated with its disposal. Therefore, its utilization in geotechnical engineering applications allows bulk consumption. However, understanding the leaching behavior of trace elements prior to its application is essentially. Accordingly, in the present study, the leaching characteristics of coal gangue were analyzed with varying the sizes of the specimen. The coal gangue was pulverised and the fraction passing 0.425 mm, 1 mm, and 4.75 mm sieve sizes was considered for the study. The toxicity characteristic leaching procedure (TCLP) has been adopted for studying the leaching phenomenon of selected trace elements like As, Cu, Se, and Ni. The study has revealed that the rate of leaching of these elements was observed to vary with size of the specimen and higher amount of leaching was noticed for smaller size specimen (0.425 mm). The decrease in pH of the extracted leachate for smaller size fraction enables the amenable mobilisation of trace elements. Further, the increase in interaction time also contributed for greater mobilisation.