Petroleum coke with very low sulfur content is used to produce graphite electrodes abroad. About 1.0% Fe: 03 was added to the mixture,
It mainly suppresses the gas expansion in the graphitization process, which is conducive to reducing crack scrap.
The blank is installed in the graphitization furnace. When the temperature rises above 1400 ℃, hydrogen, nitrogen, sulfur and other elements will be expressed as H:, H: s, CS2,
N:,NH。 A large number of studies show that nitrogen is released at 1400 ~ 1900 ℃, and sulfur is released at 1400 ~ 1900 ℃
The element is released in the range of 1700-2100 ℃. At this time, the plastic coke pore wall is subjected to the pressure of the exhaust gas,
The volume expands. It can be inferred that the expansion is mainly caused by the escape of sulfur, nitrogen and their compounds. Therefore, in the
The expansion of the electrode during 1700 ~ 2100 ℃ is called gas expansion. The mechanism of inflation is still under in-depth study, and most scholars
It is believed that the gas expansion of petroleum needle coke is caused by sulfur. A small amount of inflation inhibitor is added during batching to delay impurities
For the release of qualitative gas, the expansion inhibitor usually uses iron oxide powder, and the inhibitor reacts with sulfur to form sulfide, then at a higher
It decomposes elemental sulfur at a relatively low speed at the temperature of. The effect of metal oxide on preventing gas expansion is due to the stability of its sulfide
Qualitatively, when iron oxide is used as the inflation inhibitor, the sulfur escape is delayed to 2100 ~ 2500 ℃.