Coke strength is an indicator of physical strength of a coke made from a particular coal. Coke
needs to be strong to support the iron ore and coke mix above it in the blast furnace.
Reactivity and Strength After Reaction
The test is based on a procedure developed by Nippon Steel Corp in the 1970's as an attempt to
get an indication of coke performance and is used widely throughout the world evaluate coke “hot”
strength. The test studies the effects of one of the key coke reactions in the blast furnace on the
strength of the coke. In the testa 200g sample of –21mm +19mm square hole coke (usually
prepared by crushing 10kg of +25mm coke) is heated at 1100 C under 1atm pressure of carbon
dioxide for 2 hours. The coke is cooled under nitrogen and the weight loss during reaction is
determined. The percentage weight loss is known as the reactivity (CRI). The reacted coke is
placed in an I drum (no lifters) and subjected to 600 revolutions. The percent of material removed
from the drum that is +10mm square hole is known as the coke strength after reaction (CSR). The
test procedure is shown the figure below.
Generally a high CSR indicates a strong coke.
Reifensteinin (2003) examined the standard, with particular reference to a set of variables which
were possible sources of variation within the coke reactivity test.
The earlier work of
Pearson (1989) examined the influence of geology on CSR.
