Accessibility and effects of binder types on the physical and energetic properties of ecological coal

The objective of this paper was to determine the effects of binders on the physical and energetic properties of briquettes as well as their accessibility. Proximate analysis and investigation on binder cost on local market were conducted. The results show that the addition of binder increases the durability and density, but decreases the LHV of briquettes. However, when the LHV of the binder is higher than that of the biomass used for briquette making, the LHV will increase. Among the binders used, cassava starch contains more LHV (19.082 ± 0.381 MJ/kg), followed by cow dung (17.088 ± 0.274 MJ/kg), arabic gum (16.015 ± 0.631 MJ/kg), bark of Grewia bicolor comes last with 14.020 ± 0.272 MJ/kg, and black clay does not contain energy. For a piece of briquette which weighs 20 g, bark of G. bicolor gives a better hardness with a crushing limit load of 22 kg, followed by arabic gum with 19.5 kg, and cow dung with 14 kg. Similarly, bark of G. bicolor gives the higher density, followed by arabic gum. A kg of gum arabic, G. bicolor and starch costs between US$ 1.60 and 3.17. It is important to afforest the plant species that produce binders.