ASSESSMENT OF CLAY PROCESSING RESIDUE FOR ABRASSIVE APPLICATION

Abstract

Clay deposits are normally processed for the clay mineral content, while the residues from the processing are often dumped as earthen wastes. This work was carried out towards obtaining value added application for this residue. Residue from processing a clay deposit was characterized via quantitative XRD and XRF to identify the mineral and elemental makeup while the grains morphology (size and shape) were studied via optical microscopy, sieve and image analyses. The residue was found to be 97.26% quartzite occurring at nominal particles sizes (d^) below 600μm and the X-ray fluorescence spectrometer that was used to confirm the mineralogy of the residue shows the abundance of silicon to be 93.81% at the same nominal particle sizes (d^) below 600μm, while circularity values and the ferret dimensions indicate equant, angular and sub-angular particle shapes. Quartz being with Mohs hardness of 7, and the residue being in this fine size range, the residue was considered a probable raw material for abrasive application, although, some extent beneficiation or purification was considered necessary. This prospect was explored in the second stage of the investigation. Acid leaching was experimented to leach some ferrous matter, and the abrasiveness of the residue was actually assessed, endeavoring to follow the ASTM F735 specification, using a modification of the ASTM G-105 rotary abrasive tester constructed in the department. The grains were found to effectively abrade the test mild steel box, attaining a mass loss of 0.003 g/min at 80% pulp density of residue over 25 minutes of abrasion. This is a definite indication that the residue can surely serve for abrasive purpose. Typical abrasive products, coated abrasive sheets of varying grits (P220, P80, P40 and P30) were then produced using the residue, adapting literature procedure within facility constraints. The performance of the abrasive sheets was evaluated, by adapting the polishing table as a rotary wheel abrasive tester. The sheets effectively grinded test aluminum and mild steel alloys, with a wear of 0.39045g and 0.4109g per 10g of aluminum and mild steel alloys respectively in 25 minutes of 120rpm. From the characterization, the abrasiveness test and the test product, clay processing residue will effectively serve for many abrasive applications, such as the coated abrasive sheet (sand paper, grinding paper, polishing paper). The residue are in fine sizes ranges and this is a notable plus in this prospect, as sizing operation is a major cost component in processing solid minerals for direct industrial application. Mineralogical composition analysis, dissemination size, and shape description of the grains have been assessed and the results indicate that the residue deserves being classified as raw material resources for abrasive grains.