Manufacture of high density carbon blocks by self-sintering coke produced via a two-stage heat treatment of coal tar

High-strength and high-density carbonized carbon blocks from self-sintering coke were manufactured using coal tar and two-stage heat treatments (1(st) and 2(nd) stage treatments). First, the molecular weight distribution of the refined coal tar was controlled through a pressured heat treatment (1(st) stage treatment). Second, the 1(st) stage heat-treated coal tar (1S-CT) was treated using a delayed coking system (2(nd) stage treatment) to become the self-sintering coke. Finally, carbon blocks were molded from 2(nd) stage heat-treated coke (2S-C) and carbonized at 1200 °C for 1 h. Through rapid decomposition of the high molecular weight components in the coal tar at 360 °C in the 1(st) stage treatment, the molecular weight distribution of coal tar was confirmed to be controllable by the 1(st) stage treatment. Swelling during carbonization was observed in carbon blocks manufactured from 2S-C containing more than 15 wt% of volatile matter from 150–450 °C. The optimum conditions of the two-stage heat treatments were confirmed to be 300 °C for 3 h and 500 °C for 1 h. The highest density and flexural strength of the carbonized carbon blocks manufactured from 2S-C were 1.46 g/cm(3) and 69.2 MPa, respectively.