Testing of briquettes made from Witbank coal fines with polyvinyl alcohol as binder

Abstract

Approximately 12% of South Africa’s mined coal can be classified as fine coal. Fine coal is primarily formed through mechanical mining methods and can cause blockage in equipment, transportation mechanisms and silos. Agglomeration methods are therefore used to simplify the handling of coal fines as well as enable the use of the fines in industrial processes. This report focuses on the briquetting of coal fines from the Witbank area. Polyvinyl alcohol (PVA) was used as the binder and mechanical strength tests, i.e. compressive strength, impact resistance, abrasion resistance and water resistance, were used to determine the effectiveness of the binder. Thermogravimetric analysis (TGA) was used to determine the reactivity of the briquettes and the estimated cost of the briquettes was compared to binderless briquettes to determine the financial feasibility of the binder. The optimal briquette was determined to have a formulation (PVA vs. water) of 5% and a dosage (binder vs. coal) of 0.9% with a 7% increase in compressive strength and a 3% increase in price. The calorific value, 20.7 MK/kg, and the ash content, 26%, of the coal was not impacted by the PVA in the binder. However, neither the paraffin nor the spray increased the water resistance of the briquettes and other waterproofing methods should be investigated