Co-Pyrolysis Characteristics and Product Distributions of Coal Tailings and Biomass Blends

In order to make better utilization of coal tailings (low quality production after coal preparation) as the resources, the pyrolysis characteristics and product distributions during co-pyrolysis of coal tailings together with biomass at different ratio (20%, 40%, 60% and 80%) were determined in thermogravimetric analysis (TGA) and a fixed bed reactor in this paper. Coal tailings (TC) selected was provided by Hexi coal in Shanxi province, and pine branch wastes (PBW) were used as biomass samples. The result of TGA experiments indicates that the temperature corresponding to the maximum pyrolysis rate exhibited a significant difference between TC and PBW, and the value of the calculated TGA and DTG curves is similar to the experimental ones. In a fixed bed experiments within a temperature range of 25-900°C, gas product yields of co-pyrolysis of TC and PBW are higher than those of the sum of them individually, while tar and char yields were on the contrary. It shows some synergetic effect exists during co-pyrolysis process of TC and PBW blends, and the maximum synergy exhibits with a PBW blending ratio of 40%. CO yield increases up to 30% at 400°C and CH4 yield increases up to 11.33% at 700°C compared with the calculated value. These findings can potentially help to understand and predict the behavior of coal tailings/biomass blends in practical systems.