High strength clean briquettes production from long‐flame coal fines by using polyvinyl alcohol and coal slime as binders

Abstract

AbstractHigh strength clean briquettes production by using recycling coal fines is of great realistic significance in saving coal resources and protecting the environment. Blends consisting of a long‐flame coal fines and coal slime (CS) and polyvinyl alcohol (PVA) as binders were used in the preparation of briquettes. To produce a qualified clean briquette with enough briquette strength, the effects of the binder content, briquetting pressure, and moisture content were systemically investigated. The results indicated that the briquettes prepared by using blended binder with 20 wt.% of CS and 1 wt.% of PVA showed better compressive strength (10.2 MPa) and drop strength (98.3%). CS with particle size less than 0.2 mm could fill in the gap between the coarse coal particles uniformly, thus reinforcing the embedded state and leading to a higher briquette strength. Moreover, the strength of the briquettes was also affected by the briquetting pressure and moisture content. At briquetting pressure of 60 kN and optimum moisture content of 14%, the highest briquette strength was achieved. The hydroxyl content of the briquettes by adding CS and PVA increased significantly. In this condition, a highly viscous network colloid was formed when the PVA and water were mixed together. When the briquettes were dried, the colloid could produce a dendritic structure, which was mechanically embedded between adjacent coal particles.