Assessment of fly ash based sand as a perspective alternate backfill material for stowing in mining activity

Due to the paucity of river sand and increased regulations on sand mining, mine fill voids are kept emptied, fostering the demand for alternate backfilling material. This study attempts to develop fly ash based sand (FAB Sand) using abundantly available fly ash alone as resource material and explores its suitability as a stowing material in mine void applications, including both underground and open mining activity. Since sand within particle sizes from 4.75 to 0.075 mm is explicitly used for stowing applications, FAB Sand is developed within the same particle size range. Its applicability is evaluated in terms of physical, chemical, mechanical, morphological and mineralogical properties, and suitability is assessed by comparing vis-à-vis with river sand. Towards environmental acceptability, leaching characteristics and human health risks of FAB Sand are examined comprehensively. The findings of the study reveal that FAB Sand is not only doable and promising but could also become a sustainable alternate backfilling material for stowing in mining activities. Results pertaining to environmental acceptability endorse that FAB Sand poses no threat to ecology and human health. Overall, the proposed novel alternate backfill material and its employability alleviates the mining of sand from rivers while concurrently accentuating sustainable solutions for mining practices.