Effects of Vibratory Disc Milling Time on the Physiochemical and Morphological Properties of Coal Fly Ash Nanoparticles Omolayo M. Ikumapayi 1,a* and Esther T. Akinlabi 2,b 1,2 Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park Kingsway Campus, Johannesburg, 2006, South Africa *Corresponding Email: oikumapayi@uj.a.c.za a , ikumapayi.omolayo@gmail.com a , etakinlabi@uj.ac.za b Keywords: SEM-EDX, Milling Time, Nanoparticle, Vibratory Disc Milling, Coal Fly Ash Abstract. In this study, the mechanical disc milling of coal fly ash (CFA) produced by ESKOM thermal station in South Africa has been investigated. The present work covers the effects of milling time on the characteristics such as crystal phases, particle sizes, morphology and physiology of the powder. The produced nanoparticle powders were characterized by SEM-EDX, XRD, and XRF. The milling time was carried out at ( = 0, 20, 40, 60 )at a constant milling speed of 940 rpm. The results showed that mean area of the particles of the particle sizes increased from 75 µm size to approximately 200 nm which revealed that there was 62.5 % increase in the number of particle size as a result of disintegration of the area of particle sizes. The crystal phases detected by the XRD in CFA are hexagonal, orthorhombic, rhombohedral and anorthic. XRD analysis showed that the most dominant minerals in coal fly ash are Quartz (SiO2), Mullite (Al2.32Si0.68O4.84), Sillimanite (Al2(SiO4)O, Calcite high (CaCO3), Hematite (Fe2O3), Microcline (KAlSi3O8). It was also revealed by EDX that the main elemental compositions present in CFA are silicon, aluminium, calcium, iron, titanium and magnesium. It was established in the study that the duration of the milling affects volume, surface area, particle size, pore size distributions, as well as microstructure. 1. Introduction The fly ash (FA) is a powdery particulate biomaterial which is driven in the flue gas thereby collected either by mechanical or electrical means. Coal Fly ash (CFA) is a fly ash generated from thermal power stations in most countries of the worlds [1]. It was proven that combustion of CFA in thermal plants produces the emission of NOx, SOx and other toxic gases alongside with ample of FA. It is a storage for essential minerals but is deficient in phosphorus and nitrogen which are needed for agricultural productivity[2]. Fly ash has proved to have a good performance and is environmental friendliness; and is also as an economical substitute for the costly raw materials [3]. In recent years, many researchers have developed interest in exploiting the utilization and advances in up-cycling technologies of fly ash, by so doing promoting the value-added applications of fly ash such as reinforcements, fillers, additives, purifiers, as well as a suitable raw materials in brick making and concrete[4], [5], zeolite synthesis, geopolymers, remover of acid mine drainage[6], organic fertilizers, ceramic glazes, landfilling, forestry and agricultural applications, catalysis, soap making as caustic potash, roads and embankment, wasteland reclamation, waste treatment, adsorptions of metals and colours from wastewater, prevent topsoil loss etc [7], [8]. It was revealed that FA particles are fundamentally controlled by the temperature of the combustion, rate of cooling and particles compositions[9]. In the past to date, a huge amount of fly ash generated from the coal power station has pose challenges in storage and handling environmentally and economically. In the past, the fly has either been disposed of into the dams and lagoon or utilized in making bricks[10]. Fly ash has been proven to have high potent pesticides. FA has a porosity of nanopores and nano dimensions which will help to hold and load other nano-compounds, as a result serves as value-addition and lowering the cost of tiles lining floor and walls, kitchens, public toilets, hospitals, bathing ghats, as well as railway stations where bacterial contaminations are high[10], [11]. Key Engineering Materials Submitted: 2018-08-19 ISSN: 1662-9795, Vol. 796, pp 38-45 Revised: 2018-11-26 doi:10.4028/www.scientific.net/KEM.796.38 Accepted: 2018-12-27 © 2019 Trans Tech Publications, Switzerland Online: 2019-03-22 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.scientific.net. (#113275199-11/03/19,11:35:25)