The effect of substituting fractions of imported coking coals with coke oven tar on coal blend, carbonization, and coke properties
SS Makgato, R.M.S. Falcon
In this study, coke oven tar additions over a range of 0–8 wt.% were
evaluated as a possible substitute for imported coal fractions. The
coke oven tar used was collected from tar decanters in the byproducts
section of the coking plant. The moisture content in the tar
varied depending on the residence time and water carryover from the
coke oven tar separators to the storage tanks. Moisture contents of 1
wt.%, 3 wt.%, and 6 wt.% were investigated in order to evaluate the
effect on coal blend, carbonization, and coke properties. At 6 wt.%
moisture content with 6 wt.% coke oven tar, although the coke
quality improved the yield showed a 4% decrease. On the other hand,
1 wt.% moisture content with coke oven tar of 6 wt.%, increased the
yield by 1% and the coke quality improved. However, the latter
process was characterized by an excessive increase in wall pressure
and pushing energy, both of which are detrimental to the oven walls.
The optimum moisture content in coke oven tar was found to be 3
wt.% with a coke oven tar addition of 6 wt.% in the coal blend. With
these conditions, the coke properties improved and wall pressure and
pushing energy were acceptable. However, a decrease in coke yield of
up to 2% was observed. Despite this, coke oven tar addition is
considered to be a viable option based upon economic factors of a
reduction in the quantity and cost of imported coking coals that is
required to achieve the same optimum final coke product.
Keywords
coal substitution, coke oven tar, tar moisture, coal blend, coke, coke
quality.