Study on the Influence of Different Preheating Conditions on Carbon Structure of 1/3 Coking Coal

The 1/3 coking coal, a kind of typical coking coal in the cokemaking process, was used as raw materials in this study. Coal materials were preheated to 200 °C, 300 °C, 350 °C, 380 °C, 400 ℃, and 420 °C, respectively, by two ways, one way was putting them at room temperature in a heating furnace and let their temperature rise with the heating of furnace (slow preheating), another way was heating coal with hot gas heated to a certain temperature (quick preheating). The heating rate of coal was about 2–4°C/min in the former way and ranged from 14.40 to 28.44 °C/min in a second way. The Raman spectra of coal chars over the range of 800–1800 cm⁻¹ were curve-fitted with 1 structural ordered band (G) and 4 defect bands (D₁, D₂, D₃, D₄). In temperature range of 200–350 °C, the degree of organization of coal chars raised with increasing temperature and the quick preheating made the carbon structure of coal more disordered than those of raw coal and slow preheated coal chars. When preheated to 380–420 °C, the plastic mass emerged in coal bed and the degree of organization of samples under all preheating conditions increased overall.