Introduction

Lignite is a crude form of coal, which is peat by diagenesis formed humic coal, low degree of coalification, brown, dark brown, dark or asphalt luster, no caking. Its physical and chemical properties between peat and bituminous coal. High moisture, large volatile matter, small density, containing humic acid, the oxygen content is often 15 ~ 30%, easy weathering fracture in the air, spontaneous combustion in the air. According to the Chinese coal, classification standard is divided into two small categories: light transmittance PM 30-50% of old age lignite and PM less than or equal to 30% of young lignite. China and Indonesia lignite are elderly lignites.