It is critical for clean and efficient utilization to study the effects of the demineralization process on the chemical structure and reactivity of coals. In the study

Zhundong raw coal was processed using HCl-HF-HCl and HF-HNO3-HCl methods. The structures of both the raw coal and demineralized-coal were characterized by FT-IR

and their reactivities were analyzed by using a micro fluidized bed multistage gas-solid reaction analyzer. The results show that acid treatment is able to reduce the ash content of coal to the level under 0.2%. The intensity of absorption peaks near OH and COOH in demineralized coal was significantly enhanced. The aliphatic side chains and the substituent on aromatic ring became shorter. A huge amount of silicon and aluminum minerals were removed by the HF treatment process. HNO3 can react with organic matter in coal which leads to further increase in the content of oxygen functional groups. The combustion reactivity of demineralized coal is significantly lower than the raw coal at 600℃ and 700℃

but as the temperature rises to 800℃ and 900℃

the difference of combustion reactivity between the two kinds of demineralized coal and the raw coal becomes smaller.