Gold Hill daily news. [volume] (Gold Hill, N.T. [Nev.]) 1863-1882, 1880-05-25
C0uCEHrRArIoN.

Il
In the working Of large bodies OF low
Grade ores such a. are known to exist oil
along the Comstock. the object Is OF
course to make the ore pay for the work
ing. The reason Why those large bodies
OF low grade ore are not being worked at
the present time Is because former work.
ings have practically demonstrated that
n cannot be done with profit ct present
cost Of extraction, milling. Transports
ton. mining supplies, etc. For this
reason II 10 that such persistent search
has been and il being made through
deep shafts. at immense expense. for
rich ore bonanzas in the deepest work.
ipgs. such - have already been found
and worked out. But a. no moro OF
such desirable bonanza arrangements
are tansibly apparent just now. and
the prospect for eneounterins any Is
not particularly encouraging. tho natural
desire Of all interested In the resources
Of the country and especially Of the
Comstock IL to see these low grade ores
worked II capital can be induced to mako
the attempt. The idea Of concentrating
these ores before milling has never been
taken into practical consideration. The
cost Of extraction il much less Of q point
for consideration than the Transports
ton. milling. sto. II ten tons OF low
Grade ore can DO concentrated into n
Of high grade. 1t Is easy to sse what q
vast saving would be the result in trans
p~ortation and milling. The best. cheap.
est and most effective method OF con-
csntration Ia the main point to be con.
sidsred. Various devices have been in
vented and brought into use for the
purpose. but the most successful thus
far, Of which we have read or heard. Is
one which has been for many years in
use in the old country. and which Is
thus described In the San Francisco
Stock Report:
There Is In use In Cornwall. England. .
machine called Q 'jig." II 10 used for the
concentration. or. a. they call ID there. the
..dressing' Of ores. Though . somewhat
crude c~ontrivance. 10 involves . correct
principle. The principle on which the jig
acts 10 that OF gravitation. Granulated ore
10 placed on Q screen set In . box partially
allied with water. This screen 10 given .
Jumping motion. and the water. forcing
through the meshes OF the screen shakes
the mass. The gangue, being the lighter
stun. 10 forced to the top, while the heavy
particles Of ore gravitats to the bottom.
Az the gangue forms . layer ct tho top II
Is scrsped OF until at last nothing 10 left
In the Jig but the motal.
The Stock Report then goes on to say :
We have recently examined . concsn-
trating machine in this city. which may
properly bs described ~ an air,jig. The
principle 10 the same. but the agent used
Il compressed air in place Of water, and
the machine. though simple, Is not crude.
like the Cornish Jig. This machine is
known a. the Stephens Concentrator. Its
inherent principle 10 the action Of air
through graduated metal-bearing material
with . partial return vacuum. The mate
rial 10 fed into . hopper. which feeds 1t
automatically on the concentrating table.
The bed OF this table 10 composed OF. nrst
asheet Of punched metal screen then .
layer Of cotton cloth and then . sheet Of
wire cloth. This table Is called the ore
bed. Il 10 superimposed upon an air.box.
In which rides . horizontal blastplate. hav-
ing . vertical motion. and which acts ~ .
piston-hesd.
The compressed air from beneath gives
. series Of intermittent impulses to the
dry ore pulp passing over the ore bed.
which BY differences In specific gravity hus
heavier. sinking to the bottom and resting
upon the orc bed. while the lighter gangus
roc. rises :, 70 .ns '0P anu fe'" upon 'H'
The thus strstiled material upon reach.
ing the front OF the ore bed 10 divided at
,ins LIZ ,Sa ha.,;s, m,nsr.ib..
ing drawn Oh BY an adjustable gate under
meath the knife and diverted ey Al apron
Ssnaus roet nassss over the Made Of tho
separating knife or apron into another re-
eeSsse,e, sna inc sep.,auOn - Somp,e,sa,
BE- separated from quart pulp. or sand, or
placer dirt. only one machine in limo Is
USED. the dinsrense IN sPeeine grsvity %,
remains upon the horizontal ore bed,
whence an hourly removal. BY lifting the
o 0se osu ~ i canc .nV ma anne IN, n"r 1d"p In,a 50
pounds. with q gold saving Of over 95 per
cent. The taiiings Of this operation 90 TO
ana rseoncensrssrd until spnroIims,e
purity 10 obtained.
for sulphursts, quartz or gravel tailings,
black sand, or beach ssud. and Il IL