Arizona republican. [volume] (Phoenix, Ariz.) 1890-1930, 1903-10-27
T H E ::
MINING INDUSTRIES
Low GRADE ORE.
Its Value Increased by Modern Methods
Of Concentrating.

| The dump. and even the ore which Il
few years ago was commercially value
less. can often be made today a source
of profitable income by reason of n
more perfect understanding of methods
Of ore treatment says the Mining and
Scientific Press.
Among other branches of ore treat
rlcnt that of concentration is advanc-
ing. and taking an important place.
in Europe ore dressing has been an art
for decades past but in the western
United States the low grade ores had
been neglected because the add
vantages and practice of concentration
were not we'll understood, but it is
finding a constantly widening applica-
ton. Still in many districts too little
attention is given this important mat
ter. Ores are shipped in bulk or rudely
hnnd-sorted and the best portion sent
10 the smelters, at profit, 1t is true.
bnt at a greater cost than would be
necessary if concentration by mechani-
cal means were first employed. The
second grade ores remain on the dump
in many cases, practically waste.
though containing good values. In
some mines the ores are so distributed
Tie lHdl SOihiil6
can be carried on rapidly and econom-
ically. but this is only the case where
the ore occurs in considerable masses.
Hand sorting is not economically prae-
ticable when the mineral occurs in the
form OF disseminated grains
Concentrating machinery is designed
for specific purposes. but has consid-
cradle range Of application. Most ores
a.. ell cd a lnKN hut
some complex ores. such as those con-
tanning an intimate mixture of pyrite,
galena and blende. afford unsatisfac-
tory results. Fortunately the latter
class OF ores do net occur universally.
though found in large quantity in some
mining regions, but even this class Of
orc is now successfully treated by the
electromagnetic separator. Generally
a plant consisting of rock breakers,
rolls, trommels. jigs and concentrating
tables, huddles or belt machines are
better adapted to concentrating ores
than stamps and concentrating ma
chimes alone, for the reason that a large
percentage of the mineral is obtained
I'm the first parts of the operation, the
PARTICLES being comparatively coarse,
the fine material being collected in the
latter part of the process. Stamps crush
all portions so fine that the subsequent
recovery of the smallest PARTICLES which
In some ores crushed by stamps form
the largest portion Of the valuable min
ersl becomes a matter of great difficult
ty. In che treatment of this character
of material the hydraulic sizing cones
ana boxes are invaluable. Rolls usu-
ally MAKE - more uniform product, as
they have q tendency to crack and
NOT to grind the ore: and as most sui
phide minerals break alon~ the lines
of their natural cleavage when sub
1eoted to crushing force, the small
grains have angular faces which seem
to facilitate their separation from the
gangue. It Is the aim of the successful
concentrated to make as few shines as
possible.
When ores high grade enough to ship
without sorting are concentrated by
machinery. the gangue. if containing
values in gold and silver, may be sepa-
rately treated subsequently by ANAL
ganation or some teaching process. II
they will not pay for this subsequent
manipulation they certainly will not
pay the transportation and reduction
charges when shipped TO the smelter.
1t is a mistake which many miners
make TO send poor ore with rich. even
though the average be high. for If the
poor ore alone will not pay. it pays no
better when mingled with the high
grade ore This is a simple proposition
which seems to be lost sight of in the
desire to secure quantity. In shipping
ores the aim should be to get as high
value in as small bulk as possible.