Iron-Ore Concentration. No. 4. [Volume: 8, Issue: 4, 1889, pp. 236-240]

238

UNITED STATES ASSOCIATION OF

[VOL. 8,

lower portions of the furnace, may we not properly anticipate
increased results from a plant using them? The amount and character of the gangue of an iron-ore is of great importance to a blastfurnace manager, and one of his constant problems is the fluxing
off of the impurities. If, then, these can be be largely eliminated,
and at the same time the percentage of iron in the ore increased,
there would seem just reason for expecting that a given furnace
would require less flux, less fuel per ton of metal, less labor per
ton of iron, and less expense handling cinder, as well as less
anxiety for the manager, while an increased product from a given
furnace would reduce the charges for interest, superintendence, insurance, repairs, etc., per ton of metal made.
We have knowledge of blast-furnaces using fully one-half of the
charge of ore which averages as fine as concentrates, and doing
unusually good work; and in one case where 40 to 50 per cent. of
quite fine ore is employed, the manager is experimenting to remove
much of the magnesia and alumina, because he finds that the associated materials forming the gangue and not the comminuted ore
causes him trouble. We believe it practical to build furnaces to
work all concentrated ore, provided the mixture is not so rich as to
produce less cinder than is essential in our present knowledge for
satisfactory operation, and' we believe that a plant of moderate size
would produce as much iron with concentrates as a larger plant
with ores in the ordinary condition in which they are delivered to
furnaces, thus opening a field for most important investigation.
We are not prepared to assert that in a finely comminuted form
magnetite would smelt as easily as hematite in the same condition,
for we generally find nature breaks up with reluctance the compounds in which the element to be removed is in the smallest proportion, but we are firm in the belief that a compact magnetite is
hard to reduce on account of the difficulty of the reducing gases
reaching each particle of magnetic oxide of iron, and therefore
claim that concentrates will reduce and smelt more readily than
lumps of magnetic ore. Mr. Valentine demonstrates the fact that
dense magnetites are troublesome to desulphurize in roasting on
account of the sulphur being unable to escape. See his paper on
"Roasting Sulphurous Iron Ores," in this issue of the JOURNAI,.
We have referred only to the possibility of using concentrated