Study on Low-temperature Oxidation Heating Rate Regularity of Coal Samples with Different Particle Size

The low-temperature oxidation heating rate regularity of coal samples with six particle sizes in ningtiaota coal mine was studied based on temperature-pr ogrammed experiments system. The contrastive analysis results showed that: the heat rate would increase while the particle size of coal samples decreased, the heatin g rate curves of six particle sizes were similar and presented a W shaped trend. And each curve presented obvious stage characteristics: the normal temperature to criti cal temperature (less than 65 °C)，oxidation heating rate increased slowly; critical temperature to xerochasy temperature (65 ~ 105 °C) , oxidation heating rate decrease d firstly and then increased; more than xerochasy temperature (more than 105 °C) , the oxidation heating rate declined sharply and reached its minimum value near the chapped temperature, and then continued to grow. From micro level analysis, the various stages involved in the reaction of reactive groups, different types and quantitie s of chemical bond was the main reason to cause the heating rate presents stage characteristics.