Prospects for Obtaining Carbon Sorbents from D and DG Grade Coals

The industrial production of carbon sorbents from coal is a promising and relevant direction. The starting material is mainly brown coal, which is characterized by a high yield of volatile substances and low ash content. Of particular interest to the coal industry is the development of technology for producing sorbents from low-grade coals with a large specific surface area, high adsorption activity, and low cost. Existing methods for producing sorbents from coals that meet such criteria should be based on various thermophysical principles of influence on the source material. The work investigated one-stage and two-stage methods for producing sorbents from coal grades D and DG mined in Kuzbass. The one-stage technique consisted of steam gasification of the starting material in a fluidized bed. The two-stage technique was based on preliminary decarbonization in a muffle furnace followed by activation with superheated water vapor in a fluidized bed. As a result of experimental studies, samples of carbon sorbents were obtained from coals of low metamorphism. Analysis of textural characteristics showed that the specific surface area of the sorbents is up to 250 m²/g and adsorption activity up to 100 mg/g. It has been established that the composition of the mineral mass of the original coals significantly affects the adsorption activity of the resulting sorbents. Estimates show that the higher the ash basicity index, the higher the adsorption activity of the resulting carbon sorbent. With a one-stage method for producing sorbents from coal grades D and DG in a fluidized bed, a fairly high specific surface area is achieved with a relatively low adsorption activity in comparison with a two-stage method.