Biomass is a kind of fuel that is more and more often used in the energy industry. It supplements coal and allows it to meet the requirements of producing “green” energy and limit CO₂ or sulphur emissions. Research refers to the ash originated from the combustion of the lignite with and without the wood biomass in the CFB boiler. This article shows the results of research into physical-chemical properties of fly ash obtained from the combustion of the lignite with and without the wood biomass (wood pellet). The possibilities of the use of this ash include in suspension technologies widely used in coal mines.