Abstract:
With the increasing scarcity of high-quality coking coal resources, biomass (wood chips) as a renewable resource can be used to replace part of coking coal, significantly reducing the reliance on fossil fuels. Co-coking experiments were conducted on two types of coking coal (Kunpeng fat coal and Hongsheng coking coal) and biomass wood chips using a self-made experimental coke oven. Samples were taken at 350, 450, 550, and 650°C. The carbon microcrystalline structure during the process of mixing coking coal with wood chips for coking was analyzed through characterization methods such as thermogravimetric analysis (TG), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The TG results indicated that coking coal began to lose weight at around 400°C, and the thermal decomposition temperature decreased with the increase in the proportion of wood chips. The XRD results showed that the stacking height (
Lc) and aromaticity (
fa) gradually increased with the increase in temperature, while the lateral size (
La) and microcrystalline structure layer spacing (
d002) gradually decreased. With the addition of wood chips,
Lc and
La gradually increased. In the Kunpeng fat coal and wood chip mixture sample at 650°C, when the wood chip addition ratio increased from 0% to 8%,
Lc increased from 1.62 nm to 1.87 nm, and
La increased from 2.97 nm to 3.18 nm. The Raman results show that in the fat coal sample with 8% wood chips addition, the degree of graphitization decreases with increasing temperature, from 1.81 to 1.59, while the carbon structural order increases by 0.055 and the cross-linked structure increases by 0.74. With the increase in the proportion of wood chips, the graphitization degree decreases by 0.83, and the carbon structural order increases by 1.15, indicating that the addition of sawdust affects the order degree of the coking coal carbon structure. The XPS analysis results revealed that the aromatic structure of the coke samples increased with the increase in temperature, while the aliphatic structure gradually decreased. The thermal performance analysis results showed that when the wood chip addition ratio was 8%, the particulate coke reactivity (PRI) of the coking coal and wood chip mixture sample decreased by 2.11%, and the post-reaction strength (PSR) value increased by 6.9%. For the fat coal and wood chip mixture sample, the PRI value decreased by 6.02%, and the PSR value increased by 7.06%.