The question you pose is "can you use it".  The answers given so far only address whether it is useful to do so.  These are 2 different questions.  Whether you "can" is dependent on the quality of the Lignite.  Since it is derived by diagenesis of plant material (plants -> peat -> lignite), most of it should be acceptable from an environmental risk standpoint.  Depending on the environment in which it was formed, there may be some that is contaminated with heavy metals, high sulpher (causing acidification), etc.  So, if you do plan on using it, you should have it tested for metal content and make sure it passes local environmental standards.  Standards exist for land applications of biosolids from wastewater treatment plants - and what is regulated here is primarily metal content (Pb, Hg, Cd, As, etc.), so I assume if it meets these standards, it would be acceptable.  

Yes lignite can be effectively used as a soil amendment from the angle of its multiple utility. Earlier researches established  the use of lignite aided in improving the soil temperature. It also acts as good nutrient source , besides an effective carrier of different microbial inoculants. High amount of sulphur acts as a strong antagonists against number of soil borne diseases  caused by  Phytophthora, Rhizoctonia, Fusarium ..

It would depend on the coal, and the site specific conditions, and, if sodium or any other impairment, the application rate. In principle coal could be used directly, or in a processed form, as a soil amendment. 

For more detail refer these papers.

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwia4b2wrNzVAhVCP48KHeA9BugQFggsMAE&url=https%3A%2F%2Fwww.researchgate.net%2Ffile.PostFileLoader.html%3Fid%3D55101748d5a3f291118b45de%26assetKey%3DAS%253A273741534171139%25401442276475545&usg=AFQjCNF9Ggym5_d1K12mLCT0DPKPqrN2FQ

http://repozytorium.p.lodz.pl/bitstream/handle/11652/283/Advantages_of_lignite_Krol-Domanska_2012.pdf?sequence=1

Article Lignite amendment has limited impacts on soil microbial comm...

It would depend on the coal, and the site specific conditions, and, if sodium or any other impairment, the application rate. In principle coal could be used directly, or in a processed form, as a soil amendment. 

For more detail refer these papers.

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwia4b2wrNzVAhVCP48KHeA9BugQFggsMAE&url=https%3A%2F%2Fwww.researchgate.net%2Ffile.PostFileLoader.html%3Fid%3D55101748d5a3f291118b45de%26assetKey%3DAS%253A273741534171139%25401442276475545&usg=AFQjCNF9Ggym5_d1K12mLCT0DPKPqrN2FQ

http://repozytorium.p.lodz.pl/bitstream/handle/11652/283/Advantages_of_lignite_Krol-Domanska_2012.pdf?sequence=1

Article Lignite amendment has limited impacts on soil microbial comm...

Dear Mudammad,

yes, it is probably possible. Here is a publication on relation between humic substances and seed germination. The best substance for the seed stimulation was isolated from lignite.

Best regards, Bozena

Sera and Novak (2011) Biologia 66: 470—476. DOI: 10.2478/s11756-011-0037-y

Abstract:

In order to understand the biological activity of humic substances (HS), the effect of four humic acids (HA) and one fulvic acid (FA) on seed germination and early growth of cosmopolitan weed Chenopodium album agg. were tested. Humic substances of diverse origin were used, namely purified commercial HA, HA isolated from lignite, cambisol and podzol, and FA from mountain spruce forest soil. Data processing by two-way ANOVA has shown that type of the tested substances was a more important factor on seed development than used concentration. The major differences in germination and length of shoots were found in the first days of the experiment. Commercial and lignite HA stimulated

theseed germination andgrowth, while podzol HAinhibited them.After this initial phase, all humic substances stimulated the seed development, but these stimulations were not significant (P

I agree with Anoop, it has multiple utility. But after processing lignite can be used as a soil amendment.

Another conspicuous utility of lignite , we can visualise in developing a dynamic substrate for a variety of indoor as well as outdoor perennial crops...since it acts as an effective carrier of microbial inoculants because of high specific surface area...

Many use lignite as oxidised form of lignite called more activated version of lignite ...

The question you pose is "can you use it".  The answers given so far only address whether it is useful to do so.  These are 2 different questions.  Whether you "can" is dependent on the quality of the Lignite.  Since it is derived by diagenesis of plant material (plants -> peat -> lignite), most of it should be acceptable from an environmental risk standpoint.  Depending on the environment in which it was formed, there may be some that is contaminated with heavy metals, high sulpher (causing acidification), etc.  So, if you do plan on using it, you should have it tested for metal content and make sure it passes local environmental standards.  Standards exist for land applications of biosolids from wastewater treatment plants - and what is regulated here is primarily metal content (Pb, Hg, Cd, As, etc.), so I assume if it meets these standards, it would be acceptable.  

As earlier stated by other learned colleagues, one can, in principle, use lignite for soil amendment. However, environmental regulations in many parts of the world discourage it's use for purposes other than coal power generation. Even at that, there is a growing global campaign on the outright utilization of lignite (and coal in general) in particular for ANY purpose at all due to its high potential for GHG emissions. That said, researchers need to explore more sustainable ways to utilize the world's abundant supply of coal in the future to safeguard the planet. #My2Cents

Yes. Lignite / brown coal is high in carbon content, hence it will improve the soil C. It also has high CEC to improve utilization of added nutrients (especially N). You should however be mindful of its low pH / high acidity in determining your application rate. Some lignites have pH as low as 3.0