Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-11-11
Phosphate Rock: Its Uses and
Value.
BY CHAs. C. ScHNATTERBEcK.

@OA-So WAN
nually equivalent to 100000 ton of
available phosphoric acid. Fully one
half of this is supplied by the United
States, and the remainder is produced
in Algeria, Tunis, the Polynesian is
lands, France, Belgium and other
countries.
American phosphates carry from 55
to SO per cent. bone phosphate of lime,
and generally between and per cent.
sesquioxide of iron and alumina. The
price f. o. b. domestic shipping ports
ranges from SO to $7.25 per long ton
equivalent to to cents per unit of
bone phosphate of lime), while the quo
tation C. i. f. European ports is 1888
to $11.85 per ton III to Is cents per
until. The variation in value is eX-
planned by the difference of grade, the
higher the percentage of bone phosphate
of lime and the lower the content of
iron and alumina, the better the market
price. Iron and alumina are objection
able impurities in rock intended for the
manufacture of superphosphate or acid
phosphate for use as fertilizer. The
agricultural industry consumes by far
the largest part of the worlds produc
ton of phosphate rock, although fair
quantities are also converted into phos-
phorus and other substances which
command remunerative price.
The occurrence of phosphate has long
been the bone of contention among geo.
logical experts, and while some enter
tain the hypothesis that all phosphate
materials originated in animal life,
others are of the opinion that as apatite
in varying quantities is widely distri-
buted through eruptive rocks of all
kinds and ages its occurrence is not of
fore, leaves to the cultured imagination
of the reader the narrow path of indie
pendent research, in order that contem-
poraneous literature on this interesting
subject may be enriched, if possible.
The methods of mining and preparing
phosphate rock for market are being
gradually modified with view to mini
MIXING the cost of producing better
grade of mineral at current low prices.
Doubtless consideration is also given to
the fact that no new deposits of high
grade rock have been discovered in
Florida-the foremost producer today
in recent years. This statement sug.
gests that the life of the industry in
that section will be exhausted in the
not distant future.
Mining generally is by hand or steam
shovel, sometimes hydraulicking is more
advantageous, and when mines are
worked at water level, dredges are en-
ployed. Both steam and electricity
furnish power. When the rock has
been brought to the surface it is usually
dressed by crushing with rolls and
treated in log washers (similar to those
used for dressing iron ore). From these
washers the material is discharged into
revolving screens where careful rinsing
with clean water eliminates the sand
and reduces the percentage of sesqui-
oxde of iron and alumina. In drying
the phosphate rotary cylinders, are gen
orally used. This rotary dryer, made
by the American Process company, is a
cylindrical steel shell, 4S to So inches in
diameter and 80 feet long. 1t is pro
vided in the interior with longitudinal
shelves resting on angle irons, and near
each end of the shell is a steel tire
which rests on chilled, friction roller
wheels. These wheels are rotated by
gearing or chain betting. The dryer is
set on gentle slope to facilitate the
work The wet material and the fur
mace gases enter at the higher end.
The wet material falls to the bottom OF
the dryer, is caught by shelf elevated
to almost the highest point of the ro-
tation, and is showered through the
furnace gases. When sufficiently dried
the material is discharged at the lower
end of the dryer.
Prospecting for phosphate deposits is
perhaps not as interesting as for pre-
cious metals. A method which has re-
ceived favor is to use l 1-2 inch augei
to bore and determine whether a de-
post exists which contains enough mer.
camille phosphate to pay development
work. When the land has been proved
to be of value inch core auger is in
serted in the phosphate stratum, anC
the material raised is carefully analysed
So many discoveries have lately beer