Concentration of Iron Ores. No. 3. [Volume: 8, Issue: 3, 1889, pp. 188-195]

192 UNITED STATES ASSOCIATION OF [VOL. 8.
the ore to about three and a-half inches in size; the material from
the crusher also passing into the bin. From the bin the ore is
fed under the rams of two Ball stamps. These, as many of our
readers are aware, are practically vertical steam hammers, the admission of steam being controlled, and the number of strokes
therefore regulated, by a belt from the shafting of the plant. The
cylinders of these stamps are 15 inches in diameter by 26 inches
stroke, and the weight of the moving parts is 4,300 pounds.
These stamps are set up on.heavy timber foundations, forming
a solid frame work sixteen feet square and twelve feet deep, on
which are placed iron beams, and a timber cushion under the pan.
When visited the stamps were making 75 strokes per minute,
reducing the ore so as to pass through holes three-eighth inch in
diameter in steel plates. The material from under the stamps is
run into an iron boot in a cemented tank built below the floor
level, from which it is elevated bv buckets secured to a belt, and
washed to remove the talcose material which interferes with successful jigging From the washer the pulp is again elevated into
wooden tanks, and from these fed to five Conkling jigs of the design shown on page 8, Vol. VIII, the tails being carried away from
the building by suitable spouts, and the concentrates elevated into
a receiving tank, at the side of which runs a conveyor for automatically loading the product into cars.
The volume of water required for this plant is quite large, and
is obtained by pumping from one of the reservoirs of the Croton
water works system adjacent to the mines. The water is returned
to this reservoir from the concentrating plant.
For treating lean ores, particularly magnetites, we believe that
magnetic separation is decidedly preferable to jigging, but in
either method a careful study of the ore is essential to success.
MAGNETIC CONCENTRATION.
The number of experiments now being made with apparatus
in which magnetism is used as a medium for separating iron
ores will shortly bring results which will demonstrate its value.
These experiments are being made upon various magnetic iron
ores, as well as upon some hematites which have been subjected
to heat to change the sesquioxide into magnetic oxide of iron..While in some ores magnetic concentration which answers