Effect of Heat Treatment on Water Resistance of Lignite Briquettes

The briqutting of coal is a widely applied method for coal utilization. Water resistance of briquettes plays an important role in the storage and transportation of briquette products. In order to improve the water resistance of binderless lignite briquettes, the briquettes were heat treated and the effect of heating temperature and holding time on the water resistance of briquettes were investigated. FT-IR was employed to determine the surface characteristics change during the heat treatment process. The results showed that after heat treatment, the water resistance of samples was improved significantly. The heating temperature and holding time play different roles on the water resistance of briquettes, the higher temperature, the better the water resistance, however, a longer holding time would not guarantee a better water resist performance when the briquette had already gained water resistance through the heat treatment process. During the heat treatment process, desorption of water in the briquettes and decomposition of the active oxygen functional groups make the heat treated briquettes less hydrophilic and porous, therefore the water resistance of the briquettes is improved.