The Grindability of Biochars from Agroforestry Biomass Prepared under Different Torrefied Conditions

The torrefaction experiments of four biomass including agricultural biomass (corn straw (CS) and wheat straw (WS)) and forestry biomass (polar wood (PW) and cedar wood (CW)) were carried out in a fixed bed reactor at torrefaction temperature of 200-300°C and holding time of 10-60min, the effects of torrefaction temperature and holding time on biochar grindability based on the component analysis and the particle size distribution of ground biomass and biochars. The obtained results indicated that the mass fraction of ground biochar with particle size less than 150 μm increases with increasing torrefaction temperature, and the mass fraction of ground biochar with particle size less than 150 μm achieves 100%. The larger the λC, the better the grindability of biochar. The correlation between the grindability of the woody biochar and the λC is not as good as that of the straw biochar. The grindability of corn straw biochar and cedar wood biochar is improved with the increase of holding time at the same torrefaction temperature, however, the grindability of wheat straw biochar and polar wood biochar gets a little change, which can keep good grindability at higher torrefaction temperature large than 275°C.