Product distributions and characterizations for integrated mild-liquefaction and carbonization of low rank coals

•An integrated mild-liquefaction and carbonization of low rank coal is proposed.•The proposed technology is suitable to the efficient conversion of low rank coal.•The produced semi-cokes can be suitably used as solid fuels and even coking coals.•The caking property of semi-coke seems to depend directly on its asphaltenes.

This paper proposed an integrated mild-liquefaction and carbonization technology for the efficient conversion of low rank coals. Simultaneously, preliminary investigations on the product distributions and characterizations of the proposed technology were made in simulated process conditions. In suitable mild-liquefaction conditions (390-450 °C, 8.4-11.6 MPa), the yields of liquid products and semi-cokes are up to 23.4-33.3% and 49.6-68.7%, respectively. The produced liquid products, which are predominantly abundant with paraffins (i.e., alkanes and alkanes), alkyl benzenes (i.e., benzene and its derivatives), and alkyl naphthalenes (i.e., naphthalene and its derivatives), are potentially utilized to produce liquid fuels by further refining. The produced semi-cokes are suitably utilized as high carbonaceous solid fuels. Also, some semi-cokes can be potentially utilized for the coking of blending coals. The adopted carbonization process in the proposed technology is convenient and efficient for the separation of liquid and solid mixtures from liquefaction. Summarily, the proposed technology is greatly potential for the conversion of low rank coals into liquid products and semi-cokes.