Lignite

Classification：Sedimentary Rock

Lignite is the mineral coal with the lowest coalification degree. A brownish black and lustrous low rank coal between peat and bituminous coal. Chemical reaction is strong, it is easy to weathering in air, it is not easy to store and transport, and air pollution is serious when burning. However, because the high quality coal is almost taken out of the air, Lignite has become the main coal used in our country, but because of the low degree of coalification of Lignite, there will be a large amount of black ash floating in the air when burning. If no coal washing and refining, a large number of inferior Lignite will lead to the increasingly serious haze problem in our country.

Physical property editing
Because it is rich in volatile matter, it is easy to burn and smoke. On the section, we can clearly see traces of original wood (formed by gymnosperms). Contains humic acids that are soluble in lye. The carbon content is 60% ~ 77%, the density is about 1.1-1.2g/cm3, and the volatile component is more than 40%. There is no thickness of the glial layer. The high calorific value of the constant humidity and ashless foundation is about 23.0-27.2 MJ / kg (5500-6500 kcal / kg). Most of them are brown or brown, and the relative density is 1.2 to 1.45g/cm3.
Lignite has high moisture content (15-60%) and high volatile content (>40%), and contains free humic acid. The air is easy to be weathered and cracked with low ignition point (around 270 degrees). After storing for more than two months, it is easy to get angry and spontaneous combustion, and the stacking height should not exceed two meters, which determines that Lignite is not suitable for transportation. So the market for Lignite is also limited.

It is mainly used for fuel in power plants. It can also be used as chemical raw material, catalyst carrier, adsorbent, purifying sewage and recovering metals.
There are usually two kinds:
(1) soil Lignite (brown coal) is loose and soft.
(2) dark Lignite (lignite) is dense and hard. It can be directly used as fuel for household fuels, industrial heat sources and power generation, and can also be used as raw materials for gasification, low temperature carbonization, etc.
In some parts of the world, Lignite is used as raw material for heat sources, fuels and chemicals, as well as for gaseous and liquid fuels. In the United States, first in the north of the Great Plains (North Dakota, eastern Montana, north-east Wyoming, north-west of Wyoming, and South Dakota) and the Gulf coast of Mexico (Alabama, Arkansas, Kansas, Luis Anna S, Oklahoma and Texas) and the states of the Pacific coast. Lignite was discovered in California, Oregon and Washington state.
China's Lignite volume is only 2118 million tons, compared with the world's Lignite resources (26229 million tons) accounting for the total amount of world coal resources (107539 billion tons) of 24.4%, the proportion is also very low, accounting for 13% of the total coal resources in the country, mainly in eastern Inner Mongolia and Eastern Yunnan, northeast and Southern China also have a small amount.
The burning value of Lignite is low, at 3000 big cards or below. The latest development technology at home and abroad is Lignite drying, which can increase its combustion value to 4800 or even 6000 calories.