Upgrading mild gasification liquids to produce electrode binder pitch: Final technical report, September 1, 1993--October 31, 1994

The objective of this program is to investigate the production of electrode binder pitch, valued at $250--$300/ton, from mild gasification liquids. In the IGT MILDGAS process, the 400 C+ distillation residue (crude pitch) comprises up to 20 wt% of maf feed coal. The largest market for pitch made from coal liquids is the aluminum industry, which uses it to make carbon anodes for electrolytic furnaces. In this project, crude MILDGAS pitch is being modified by flash thermocracking to achieve binder pitch specifications. A 1-kg/h continuous unit has been built for operation up to 900 C at 2.5 atm, and parametric tests were conducted in N{sub 2}, H{sub 2} and 50% H{sub 2}/N{sub 2}. In general, thermocracking at 750--850 C in N{sub 2} resulted in a pitch which meets binder pitch requirements for QI, TI, softening point, and C:H ratio. Further improvements in density and sulfur content are required. Test anodes were prepared by Alcoa using the upgraded mild gasification pitch. All of the key anode properties (density, strength, resistivity, thermal properties, permeability, and reactivity) compared very favorably with those of electrodes made from a standard pitch binder