Iron-Ore Concentration, No. 5. [Volume: 8, Issue: 6, 1890, pp. 349-353]

No. 6.]

CHARCOAL IRON WORKERS.

349

Iron-Ore Concentration, No. 5.
CONCENTRATED iron-ores are usually considered as those which
have passed through sizing and jigging or sizing and magnetic
separating processes, and the term is more commonly applied to
magnetites than to hematites, but we may properly consider any
method of beneficiating iron-ores in this discussion.
In other words, we may refer here to any means of increasing the
percentage of iron in an ore by separating from it all or a part of
its gangue under the general caption of concentration, and therefore
in this category, washing or jigging processes may be considered.
The roasting of iron-ores is to a certain extent a concentrating
process, but their purpose is seldom one of separating the gangue
from the ore, but rather of driving off moisture, sulphur, or carbonic
acid; and this treatment is generally recognized as that of " roasting or calcination." The system of washing brown hematites
approaches in results those obtained by jigging and may fairly be
considered under the general head of concentration.
Various forms of ore-washers have been referred to in the
JOURNAL, vol. v., page 102, in the description of the Cripple creek
region in Virginia. In vol. v., page 366, as used in the Salisbury
region, Connecticut. One in use at the Shelby Iron Works,
Alabama, was illustrated in vol. vi., page 578, and one used at the
Copake Iron Works was illustrated and described in vol. vii., pages
6 to 11.
The use of the washer has developed more largely in Virginia,
Georgia, Alabama and Tennessee, than elsewhere lately, but the
forms principally employed are either the shaft or the cone
washers. The shaft washers are single or double, the latter being
preferred, and consist of one or two logs of wood iron bound and
fitted with blades; these logs revolve in a trough in which the ore
and water are placed, the revolving blades cutting up the clay
lumps, and forcing the ore up the inclined bottom of the trough,
the water carrying away the clay to suitable settling reservoirs or
mud dams.
In some instances iron shafts have been used in place of logs, and
the most approved arrangement is to have paddles which slip into