Carbothermal Upgrading of the Awaso Bauxite Ore using Waste Pure Water Sachets as Reductant*

Abstract

Waste Pure Water Sachets (PWS) are currently among the fastest growing solid wastes generated in Ghana. Government’s attempt at banning its production and usage has been thwarted by the realisation that such a measure will increase the unemployment rate since the sachet water business employs a significant proportion of people. Meanwhile, the country currently exports its bauxite raw, without any value addition. Gradual depletion of high grade bauxite (with high alumina content) and the emergence of low grade bauxite with high iron oxide content calls for novel and inexpensive ways to upgrade these low ores. This project investigates a simple way of generating carbonaceous materials from PWS and their subsequent utilisation as reductants in the carbothermal upgrading of the Ghana Awaso bauxite. Samples of PWS were heat-treated in the temperature range 130-180 °C and the resulting molten material was cooled to render it brittle. The brittle mass was then pulverised and characterised by XRD and SEM. Composite pellets of bauxite sample and pulverised PWS were then formed, oven dried, placed in a fireclay crucible and heated in a gas-fired furnace. The magnetic fraction after reduction was separated by a Low Intensity Magnet and weighed. XRD analyses of the pulverised PWS showed peaks identical to those of high density polyethylene (HDPE). It was further observed that after about 30 min of firing, a large portion of the sample could be attracted by the magnet, indicating the suitability of the waste polymer as an important carbonaceous material for bauxite upgrading. The use of PWS as reductant prevented the formation of hercynite (FeAl₂O₄).

Keywords: Pure water sachets, Bauxite, Gas-fired furnace, Magnetic fraction, High density polyethylene