Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Degradation of Coke due to Alkali Adsorption
Tongshik CHANGMitsuru TATE
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1979 Volume 65 Issue 5 Pages 479-487


A fundamental study on the degradation by alkali adsorption of two cokes made from ordinary (A) and specially inferior (B) coal blends, which had been used in the 26th run of the experimental blast furnace, was carried out.
Following results were obtained:
1) The rate of alkali adsorption at the temperature ranging from 800 to 1000°C in N2 atmosphere depends on the initial porosity of coke.
2) Alkali is adsorbed by either coke and its rate near 1% of enough to generate macro-cracks. The degree of macro-crack formation increases with the increase of alkali adsorption, and it is higher in the less porous coke (A) than in the more porous one (B) under the same rate of alkali adsorption.
3) The presence of CO2 in the atmosphere diminishes macro-cracks due to alkali adsorption, and the crack formation is completely prevented at some PCO2 higher than 0.05-0.06atm.
4) Micro-strengths of every macro-cracked cokes and of coke fines generated by alkali adsorption decrease extremely.
Alkali adsorption is considered to be a cause of degradation common to all kinds of coke, but it is difficult to regard it as the cause of remarkable degradation of coke (B) in the 26th run.

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