Hw. Gudenau et al., TRIALS TO INJECT PULVERIZED COAL IN COMBI NATION WITH FINE-GRAINED IRON-ORES INTO BLAST-FURNACES, Stahl und Eisen, 117(6), 1997, pp. 61
Objective. In view of the increasing share of fines accruing worldwide
in the mining and dressing of iron ores, it was investigated and disc
ussed whether a direct use of fine-grained iron oxides in blast furnac
es is realisable without any agglomeration. The combined injection of
pulverised coal and are fines was researched by basic experiments to d
etermine the reaction mechanism, by calculations of the name temperatu
re, and by means of pilot trials at a char coal blast furnace. Summ. T
he findings of the laboratory experiments confirm the evaluations reac
hed in previous work, namely that fine-grained iron ores can be reduce
d,within a matter of milliseconds, to the state of metallic iron. Coal
grades with a high proportion of volatile constituents displayed a lo
wer reduction potential than low-volatile coal grades, which can be at
tributed mainly to the differing devolatisation, ignition and combusti
on behaviour. The calculations of the adiabatic name temperature revea
led that a fall in the flame temperature can be counteracted by oxygen
enrichment. In the pilot trials a facility was developed with which i
t was possible to achieve continuous injection rates of up to 500 kg o
re fines/h through an experimental tuyere over several hours. No incre
ase in pressure to indicate a loss of permeability in the raceway was
observed at the experimental tuyere.