Analysis on Spontaneous Combustion Characteristics of Adding Associated Sulfur Minerals in Coal

ABSTRACT

In order to further study the influence of associated sulfur minerals on spontaneous combustion and ignition characteristics of coal, four coal samples with different sulfur contents were prepared by adding different sulfur minerals to raw coal, and through Thermogravimetric Analysis (TG) experiment, Differential Scanning Calorimeter (DSC) test and X-ray diffraction (XRD) analysis, the influence of associated sulfur minerals on spontaneous combustion and ignition characteristics of coal was studied. Experimental results show that with the increase of associated sulfur minerals, the characteristic temperature of coal decreases, while the oxygen absorption, flammability and incombustibility stability index increase gradually, indicating that the coal is more prone to spontaneous combustion after being mixed with the associated sulfur minerals. Based on Coats–Redfern method to calculate the activation energy of coal during combustion stage with different associated sulfur minerals in coal, the calculation shows that the activation energy of coal combustion stage decreases with the increase of the associated sulfur minerals in coal and makes it easily to burn. Through the XRD and DSC analysis of associated sulfur minerals, it is found that the main components of the associated sulfur minerals are melanterite and copiapite, which can react with water and oxygen at room temperature, and the exothermic reaction makes coal more prone to spontaneous combustion. The associated sulfur minerals are exothermic after 200°C and reach an exothermic peak at 565°C, which makes the activation energy of coal in combustion stage decrease and coal easily to burn.

KEYWORDS:

• Coal spontaneous combustion
• associated sulfur minerals
• flammability index
• incombustibility stability index
• activation energy

Additional information

Funding

This paper was supported by the National Scientific Foundation of China (Nos. 51304069 and U1361205): No. 51304069: Person in charge: Minggao Yu; project type: Joint fund projects; Department of Engineering and Materials Science; approved in 2013. No. U1361205: Person in charge: Hailin Jia; project type: Youth Science Fund Project; Department of Engineering and Materials Science; approved in 2013.Other fund projects are school or national projects, and the authors guarantee that they are true and effective.