In this study, coke oven tar addition over a range of 0 – 8 wt.% was evaluated as a possible
substitute for imported coals fractions. Coke oven tar used was collected from coke oven tar
decanters of the by-products section of the coke making plant. Moisture content in coke oven
tar varied depending on the residence time and water carryover from coke oven tar separators
to storage tanks. Therefore, various moisture ranges were considered in order to observe its
effect on coal blend, carbonization and coke properties. The optimum moisture content in
coke oven tar was found to be 3% with a coke oven tar addition of 6 wt.% in the coal blend.
At the same coke oven tar addition of 6 wt.% in the coal blend but with 6% moisture content
in coke oven tar, coke properties improved, coke yield showed up to 4% decrease. On the
other hand, with 1% moisture content in coke oven tar of 6 wt.% in the coal blend, coke
yield increased by 1% and low coke properties such as I40 of 42.9 and Stability of 50.3 were
achieved. The latter process was characterized by excessive increased in wall pressure and
pushing energy. Both wall pressure and pushing energy increase are less desirable due to
their detrimental effect on the physical condition of the oven walls. Furthermore, addition of
coke oven tar with 1% moisture content to coal blend can be prohibited by its high viscosity.
At 3% moisture content in coke oven tar addition of 6 wt.% in the coal blend, coke properties
improved. When the amount of coke oven tar was increased to 8 wt.% at the optimum coke
oven addition, coke yield was not affected but low CSR of 57.8 against a target of ³60 was
achieved as opposed to CSR of 65.4 at 6 wt.%. Also, coke stability of 52.2 at 8 wt.% as
opposed to 56.1 at 6 wt.% was achieved. Moreover, the highest I40 of 50.9 was achieved at 6
wt.% whereas with 8 wt.% coke oven tar, I40 of 47.9 was achieved. However, up to 2%
decrease in coke yield was observed. Despite this 2% decrease in coke yield, coke oven tar
addition is a positive and viable option based upon economic factors (i.e. this reduces the
quantity and cost of imported coals and still achieves improved coke quality which result in
improved blast furnace operation and better hot metal quality).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/16732 |
| Date | 23 January 2015 |
| Creators | Makgato, Seshibe Stanford |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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