Briquetting optimization method for the lignite powder using response surface analysis

Abstract With the vigorous development of lignite in the global region, the upgrading technology of lignite has gradually matured and a large amount of pulverized coal is produced during the upgrading process. And the pulverized coal is special in nature and difficult to process and utilize. In this paper, the briquetting of upgraded lignite powder was carried out by cold pressure methods with external binder. Response Surface Methodology (RSM) by Design Expert software was used to analyze the briquetting of the upgraded lignite powder with PVA solution as binder. It revealed that the interaction between the molding pressure and the amount of water addition as well as the drying time and the binder mainly affected the falling strength of briquettes. Regression analysis indicated that the optimum molding conditions were: 19.70 MPa of molding pressure, 0.52% of PVA binder addition, 21.61% of water addition and 5.65 h of drying time. Simultaneously, the predicted value of falling strength of the model is 98.67%. This is close to the experimental value (98.72%). The analysis of wettability, SEM and zeta potential shows that these briquetting conditions can make briquettes better.