Briquetting and its mechanism of anthracite under low mass ration of binder

Anthracite briquette, possessing certain particle size, cold strength and ther-mal strength, can partially replace lump coal for gasification in ammonia synthesis.Shanxi anthracite is high-quality raw material for coal gasification, and the related stud-ies are of great significance because of the limited resource reserves.Herein, using Shanxi anthracite powder as the raw material, the briquettes were prepared using a manual briquetting machine based on the binders of modified biomass and bentonite as well as small amount of additive.The influence of the binder ratio on the briquette properties was investigated according to the cold strength and thermal strength of as-prepared briquettes.The corresponding briquetting mechanism was also studied by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron micros-copy (SEM).The results indicate that with the increase of the additive amount of modi-fied biomass or additive solution concentration, the cold strength and thermal strength of as-prepared briquettes both increase first and then decrease, which will increase with the additive amount of bentonite.The optimal process parameters of briquette were de-termined as follows:anthracite 95.3%, modified biomass 1.5%, bentonite 3%, additive 0.2%.The as-prepared briquette exhibits a cold strength of 589 N/ball and a thermal strength of 220 N/ball, with the similar coal analysis results to the raw coal, and its physicochemical properties can meet the gasification requirements.The additive cannot only help to partially hydrolyze the biomass to generate small molecular compounds and other substances, but also convert the silicon oxide in the coal into sodium silicate, resulting in an improvement of the bonding effect between the coal particles and the binders.Large coal particles in the briquette are surrounded and fixed by small coal par-ticles, binders and the additive.Noticeably, the additive amount of briquette binder is less than 5%, the production cost is approximately 30 Chinese yuan per ton of briquette, which is superior to that reported in the literature and in the industrial production.