Unreduced Ore Passing Through a Blast-Furnace. [Volume: 8, Issue: 5, 1889, pp. 303-305]

304

UNITED STATES ASSOCIATION 'OF

[Vol,. 8,

in fair working order. An examination showed that the brickwork on the west side of the furnace about the top of the bosh
was only 2 to 3 inches thick, while on the east side it was 9 to 10
inches. This was determined by drilling holes at intervals through
the furnace walls. In order to fill up and restore the bosh to something approximating suitable proportions, it was decided to run the
furnace on silver-gray iron in hopes that a graphitic bosh could be
formed. It was while this effort was being made that the samples
of unreduced ore were obtained from the tuyeres on the east side.
We noticed that the tuyeres on the west side worked much better
and brighter than those on the east side. The temperature was experimentally determined by driving bars of wrought-iron into the
centre of the furnace through the plug-holes of the several tuyeres.
On the west side the bars became white-hot and melted off before
they could be drawn out, while on the east side similar bars were
bright red at the points, but only dull red for the greater part of
their length. About the same time the tuyeres on the east side were
rapidly cut, exploding with reports similar to pistol shots. As these
tuyeres were removed, the stock in front of them was shovelled out
and preserved. It was from this stock that the specimens of unreduced ore were selected. At this time the stock was passing through
the furnace in about sixteen to eighteen hours, and the iron made
was chiefly No. 1. The slag was uniform and hot, the furnace was
working fairly regular, but not with the usual fuel economy or
average yield of iron. Owing to the shape of the furnace being
oblong instead of circular, it was supposed that a much larger volume
of gas ascended on the west side than on the east side. The gas
currents thus established thoroughly reduced the ore on that side,
but were deficient in quantity on the east side, and thus the ore on
this side descended without being properly acted upon, and reached
the tuyeres and crucible unreduced. The presence of unreduced
ore naturally made that side of the furnace work cold, and this again
facilitated still further arrivals of unreduced ore in the crucible.
The frequent loss of tuyeres was due to the formation of pockets
under the tuyeres, which filled with iron as it was melted, and this
iron, coming into contact with the bronze of the tuyeres, produced the
explosions. In order to correct this condition of affairs, a long
tuyere was placed on the west side, projecting 20 inches or more