twenty-four-hour
inches, The grade was light, and dump for the tailings could be
obtained only by means of direct connection made with the Patricksville
main sluice line.
With
any decrease of the radius the sluice would not run uniformly, but
would deposit tailings. The smallest radius of the curve having been
ascertained by experiment, the next question that presented itself
was. Would the main sluice carry the tailings discharged into it ? As
the main sluice was straight, and the general fall of the ground
slight, an attempt was made to economize grade and run this sluice,
with its original grade of 3 inches to 16 feet, below the junction, but
the experiment was unsuccessful. The main sluice was then taken up,
and a 1-1/2-inch drop was given from the turn-in sluice at the
junction, and the first two boxes from this point were set on a grade
of 4 inches to 16 feet, while the remaining boxes had a 3-1/2-inch
grade to 16 feet. This improved matters, but material still accumulated
in the main sluice at the junction and in the one box below. The
turn-in sluice was then given a drop of 4 inches at the junction, and
the discharge opening was increased from 11 to 14 feet; the sluices
then ran uniformly.
The
outer curve of the sluice was set a half-inch higher than the inner
side. The boxes forming the curve were made in lengths of 8 feet each,
and a grade of 2 inches given to each length. The head of the sluice
was straight, as well as the lower end below the junction.
Turn-out Sluice.—The
" turn-out " sluice is generally used when the dump-room is very
limited. It is more difficult to operate on a light grade than a "
turn-in " sluice.
At
the La Grange Company's mines the grades varied from 2-1/2 inches to 4
inches per 16 feet, and the dump-room was very limited, necessitating
many turn-out sluices and frequent sharp curves. As the dumps filled up
the sluices were extended, and every available space was utilized which
could be reached with a branch sluice.
