Evaluation and optimization of preparation for semi-coke briquette with alkali-heat treated wheat straw binder

Semi-coke briquette used in stoves could reduce the primary PM2.5 emission and lower the material cost advantages. While the manufacturing cost of semi-coke briquette is relatively high due to the weak cohesiveness of semi-coke. The cost-effective and environment-friendly briquetting technology still needs to be developed for clean utilization of fine semi-coke. A novel preparation method of semi-coke briquette with alkali-heat-treated wheat straw (AH-WS) binder was put forward in this study. The physical characteristics of the semi-coke briquette were analyzed experimentally. Infrared spectroscopies indicated that AH-WS obtained in the mixed lye comprised 4% Ca(OH)(2) and 0.04% NaOH featured higher cellulose and O-H group concentrations than those in 4% Ca(OH)(2). Therefore, the mixed lye could play a better role in briquette binding. Scanning electron microscope images revealed that higher AH-WS ratio enlarged the area of solid bridges during densification and improved the strength and density of briquette. The orthogonal analysis determined the optimum briquetting parameters were 8% moisture, 25% AH-WS, 5% clay and as low as 15 MPa forming pressure, which could obtain the semi-coke briquette with compressive strength above 20 MPa and bomb calorific value beyond 19 MJ/kg. Present work could promote the application of semi-coke briquette for household.