http://worldcat.org/entity/work/id/137501787

Final Report for Contract AT-30-1-Gen-127 (United Carbon Products Company, Inc.). Part 2. Technical

A plant for processing graphite to high purity by the United Carbon Products Company Inc. method was established at Bay City, Michigan. The facilities were capable of producing 900 lbs per day of high purity graphite. Graphite having a total ash content of 600 ppm and a boron content of <0.6 ppm was purified so that the total ash was 410 ppm and the boron was <10 ppm <0.10 ppm. The processing was carried out in electric granular carbon resistance furnaces. The purification was achieved by reacting most of the elements out by the use of carbon tetrachloride with nitrogen introduced into the heated zone up to 2000 deg C, the removal of boron is accomplished by the use of a fluorinated hydrocarbon such as difluoro-dichloro-methane (i.e. "F-12") at temperatures above 2000 deg C. The "F-l2" is used only at the high temperature level to avoid reformation of carbon tetrafluoride in the graphite being processed. jg p.4.

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