Lignite is a type of coal that contains relatively high amounts of moisture and ash. The utilization value of lignite is relatively low, but through upgrading processes, lignite can be converted into fuels with more economic value.

  The process flow of lignite upgrading mainly includes the following steps:

  First, the coal mine sends the raw lignite ore to the washing plant for the washing process. Washing is the process of separating impurities and moisture from raw ore. First, the raw ore is broken into suitable particle sizes, and then flotation is carried out through a shaker, funnel or trough selector. These devices use the different physical and chemical properties of the ore to separate impurities and lignite. With the action of vibration or water flow, lignite particles float upward, while impurities sink. In this way, impurities and moisture in lignite can be separated.

  After washing, the impurities and moisture in lignite have been greatly reduced, but it still cannot be directly used for combustion and industrial production. Next comes drying and dehydration. The process of putting lignite into a lignite dryer and using hot air to dry it. The high-temperature air generated by the hot blast furnace is blown into the equipment, and the moisture in the lignite is evaporated through heat and mass transfer. In this way, the moisture content of lignite can be further reduced and its combustion value improved.

  After drying, the quality of lignite has improved considerably, but further purification is still needed. The next step is grinding and sifting. Grinding is to crush the dried lignite to make the particles more uniform and fine. This can increase the specific surface area of lignite and improve its activity and flammability. Then, the lignite is screened through screening equipment to separate out the required particle sizes, while the rest is ground back and finely crushed.

  Through this series of treatments, not only the ash content of lignite is reduced and the calorific value is increased, but also the volatile content is reduced, the fixed carbon index is improved, and the properties of the coal are closer to the long-flame coal standard. In addition, flammable objects such as hydrogen and oxygen will be recovered during the process for combustion and recycling, thereby achieving energy conservation and emission reduction.