Abstract:

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.

Key words: Zhundong coal, demineralized coal, acid leaching, FT-IR, micro fluidized bed, reactivity

摘要：

研究酸洗脱灰过程对煤的化学结构和反应活性的影响对煤的清洁高效利用十分重要。采用HCl-HF-HCl和HF-HNO₃-HCl两种方法对准东次烟煤进行处理，利用傅里叶红外光谱对原煤及其酸洗处理得到的脱灰煤进行结构表征，并用微型流化床多阶段气固反应分析仪对煤粉样品燃烧反应性进行分析。结果表明，酸洗处理可使煤中灰分含量降低到0.2%以下，脱灰煤中OH和COOH附近的吸收峰强度显著增强，脂肪侧链变短，芳香环上取代基减少。HF使得煤中硅铝类矿物质被大量脱除，HNO₃会与煤中有机物发生硝化反应，导致部分含氧官能团含量进一步增加。当温度在600和700℃时，脱灰煤燃烧反应性与原煤相比显著降低，但随着温度升高至800和900℃，脱灰煤与原煤的反应性差距变小。

关键词: 准东煤, 脱灰煤, 酸洗, 红外光谱, 微型流化床, 反应活性