Effect of Upgraded Lignite Product Water Content on the Propensity for Spontaneous Ignition

The spontaneous ignition that occurs with upgraded lignite products is a concern for its storage, handling, and transportation. The Basket testing method and Oxidation Kinetics testing method were used to identify the propensity for upgraded lignite products to spontaneously ignite. The evaluation index for the Basket testing method was spontaneous ignition temperatures and duration. The fundamental evaluation index (I) for the Oxidation Kinetics testing method was used to evaluate the propensity for spontaneous ignition. For both testing methods, all three of the lignite samples (Huolinhe lignite, Hailaer lignite, and Indonesia lignite) showed that the propensity for spontaneous ignition decreased linearly with the increase in water content of the upgraded lignite product. Commonly used Chinese bituminous coals, which are not prone to spontaneous ignition, were used as a benchmark for determining the recommended water content for upgraded lignite products. For Huolinhe lignite, Hailaer lignite, and Indonesia lignite, the recommended water contents of the upgraded products are 6.53%, 4.28%, and 7.83%, respectively. The method that was developed to determine the recommended water content could be used to guide engineering design and operations when using upgraded lignite that is highly susceptible to spontaneous ignition.