Development and characterization of coal fly ash through low-energy ball milling

Abstract

A paradigm shift from monolithic materials to composite materials has been observed in recent times to achieve the ever changing demands of the manufacturing sector. The composites are being explored in terms of industrial and thermal power plant wastes used as reinforcements. Being a prominent thermal power plant waste, fly ash disposal and utilization is gravitating environmentalists and researchers to propose innovative ideas and feasible implementations. To trace and adjoin an effort to add value to aforementioned cause, an investigation was conducted on fly ash which was milled in tumbler ball mill with predefined input parameters viz. spindle speed, ball-to-powder ratio, and milling time. Low-energy mill has an extensive application in preparation of new materials, their activation and process of synthesis for potential merits like cost-effectiveness, reliability, low maintenance and ease of operation over its contemporary high-energy mill. The modifications in chemical and morphological properties of milled fly ash sample were characterized through X-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results inferred that the ball-milling process aimed at reducing crystallite domain size of milled fly ash, and also affected the microstructure, functional groups and led to decline in degree of crystallinity. The milling time was observed as a significant factor to impact extent of these changes. The particles of the raw spherical-shaped fly ash (regularly 5 μm size) were broken down into smaller particles of average crystallite domain size ∼ 30 nm, this change indicated an increase in amorphousness which helped in achieving better compatibility and significantly higher reactivity. The pattern and peaks of XRD for original crystallinites significantly diminished and resulted in broadened peaks. This can be interpreted by the smaller particle size and low degree of crystallinity. The research defined the achievement of nanostructured fly ash with low energy mill technique.