Economical biobinders and their blends suitable for the production of coal briquettes, heat insulating materials and other industrial applications

The aim of this study is to find a biobinder for the production of waterproof or at least water-resistant coal briquettes from the Slater coal slurry of South Africa. From an economic point of view, molasses and crude glycerol were used as raw materials for the production of binders. To obtain comparable results, the binders were prepared from either pure or crude glycerol. The results indicated that crude glycerol citric acid ester-based binders resulted in briquettes with higher tensile strength than pure glycerol citric acid ester-based binders. The optimum citric acid to glycerol molar ratio for producing the briquettes with the highest tensile strength was found to be 1:2. All the briquettes produced with the glycerol citric acid ester-based binders, regardless of the molar ratios, were water resistant but not waterproof. To produce waterproof briquettes, the binders were prepared by blending phosphoric acid-hardened molasses with glycerol citric acid ester-based binders. Waterproof briquettes with the maximum tensile strengths were obtained when the molasses-based binder to glycerol citric acid ester-based binder was blended at 50%. To confirm these results obtained with Slater coal, pumice was used in place of coal for brick production