Development of membrane based technology for the separation of coal from organic solvent

In this work, non-coking coal was extracted using of organic solvent mixture of n-methyl-2-pyrrolidone (NMP) and ethylenediamine (EDA). The coal extraction experiments were carried out at different ratios of coal to organic solvent mixture for 1 h under total reflux conditions. The optimum conditions for solvent extraction were determined. Ceramic membrane in microfiltration range was used for recovery of organic solvent from coal organic solvent mixture. Characterization of the prepared inorganic membrane was done in terms of pore size distribution, membrane porosity and chemical stability. Membrane experiments were carried out in batch cell. The mixture of coal and organic solvent obtained after extraction process was passed through ceramic membrane and recovered organic solvent was reused further for extraction process. Same steps were repeated continuously three times. The fabricated ceramic membrane showed solvent recovery of 71%, 68% and 66%, respectively, for successively three stages. The information provided in this study will be helpful to the steel making industries where pure carbon is extracted from coal using energy intensive distillation process. The amount of solvent recovery is quite high in this membrane based technique and will improve the economy of the process in a large extent compared to the existing distillation process.

► Membrane based technique proposed to improve non-coking coal to coke making economy.
► Prepared ceramic membrane had good chemical stability in pH solutions and pure NMP.
► The membrane used for recovery of organic solvent from coal organic solvent mixture.
► Recovered organic solvent, free from coal used for next extraction process.