New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1880-08-15
MINES OF COLORADO.

|
SUCCESSES AT SILVER CIIFP-rHE VALUE or
HE EXPERIENCE ACQUIRED-FUrURE OF TIE
CAMP.
Iron 4 STAFF CORRESPONDENT or THE rEIBuNEI
SILVER CLIFF, Colorado, July 23.-The chloride
ores of this camp free milling" For the bene-
fit OF those not familiar with the processes OF redu
cling gold and silver ores. brief explanation of
what this expression. 30 often used by mining men,
| means may not be out of place. In separating ny
anal gamaton the precious metals from the gangu"
| or waste rock with which they are almost always
associated il is necessary to the success OF the pro
cess to present the PARTICLES of gold or silver
contained in the ore, to the mercury with which
they are TO be alleged in such form that the latter
! can seize upon them readily If these metals al
| ways occurred in nature in their pure metallic
| state this would he "a very easy matter. In Tree
milling gold it is frequently only necessary 10
place the quicksilver beneath the stamps OF the
battery in which the ore is crushed and upon an
inclined copper plate over which tho pup Is carried
| by water after it leaves the battery. The stamps
| by reducing the rock fine PARTICLES release the
minute scales and crystals of gold which arc readily
| taken up by the quicksilver while the rock for
| which the mercury has affinity is carried away
| as tailings."
| But silver rarely in native or pure
| metallic state. 1t is usually mixed with chlorine
lead iron. sulphur, manganese, copper, ant'mony.
and other base metals, and is found in the form OF
chloride of silver, argentifcrous galena, In when
the silver is in the form of sulphIde, and IN many
other compounds for most of which quicksilver has
no more affinity than it has for the common rock OF
the gangue. In most cases therefore, If the silver
| ore was simply crushed and brought into contact
| with an amagamating surface little or mono oil the
| metal would be caught by the quicksilver ana
saved. Mercury has strong affinity for netalnc
sill, err stronger even than that Of chlorine, so that
if chloride of silver and quicksilver brought
together the mercury will seize the silver forming
| an amalgam, and the chlorine which is released
| Will escape rs gas or unto with some other sub
stance which presents itself and for which it
has an affinity; but sulphur VIII not give up silver
with which it il chemically mixed TO mercury
unless the sulphur has first been driven oft by
fire. This process of converting chloride of silver
| into an amalgam is not an instantaneous one like
the amagamaton of free gold. but requires sew
cral hours to be perfected. and it is fastened by
the presence OF other chemicals, such as sulphate
Of copper, sulphuric acid, AMI cyanide of potas-
sum- the action of which it is unnecessary to ex
plain here.
THE FIRST ESSENTIAL.
In order TO reduce silver ores by malgamatiOn, it
is necessary as will he understood from the above
| explanation. to have the particles Of metal either
in pure or chlortic state. When they are found
in nature in either of these conditions they need
no special treatment before being put into the mill
! and the treatment Of them is called raw amalga-
| nation The process employed is to crush the ore
| to fine pulp and then transfer it to a large round
iron tub where it is agitated for several hours in
hot water with quicksilver, some or all of the
chemicals l have named being added with COM
! mon salt to promote the union of the mercury and
the silver If the silver in the ore is in tho form
of a sulphidc. it frequently IS, and the amalga
nation process of reduction is to be employed the
ores have to be roasted with common salt for sew
cral hours after they crushed Without eX-
planning in full the chemical reactions, l may
simply say that the heat .voatlizes the sulphur
mixed with tho silver, and separates the salt into
its constituents of chlorine and sodium, the first Of
which unites with the silver from which the sui
phua has been driven of and forms chloride which
is then ready for the amagamating pan. The de-
sulphurization and chlorination of an is ex-
pensve process and greatly increases the cost Of
duction.
When such metals lead, zinc or copper are
present in ores in large quantities, it is usually
cheaper to reduce them by smelling. and by that
process the lead and copper also generally saved
and add to the value Of the product. Almost any
ore can be reduced by f-e if it is mixed in small
proportions with other smelling ores. In large
smelling establishments like those at Denver,
| Omaha, and Newark, n. j.. where great varieties
of ores are purchased, even free milling rock can
| be used to advantage but the reduction of most
free milling ores by fire, without mixture with
| others would be ruinOusy expensive if not physlc-
| ally impracticabe.
The ONLY PRACTICABLE METHOD OF REDUCTION
| havo entered into this explanation because of
the bearing it has upon the important question of
the best method of reducing the immense bodies of
chloride in this camp. When a prospector dis
| covers new mine in Colorado that shows up" a
considerable body of ORE the first thing he generally
] does is to ship few tons of it to Senator Hills
smelling works in Denver. There it is assayed,
price per ton flor reducing is determined according
to tho character of the Orc and the owner is paid
the value of the silver and gold which it contains
after the price and fixed percentage of loss have
been deducted. If the rock is not itself smelling
ore il is mixed with other that is and is easily
| duced.
The first ores that were mined at Silver Cliff
were sent to Canon City and reduced in the smeter
| at that place, and until mill was erected here
| whatever ore was sold went to some smcter Tho
| owners Of reduction works never complained that
the ore was hard to reduce. If it not a smel-
| ing ore they simply added something to the price
charged for treating IT, and took all they could get
When the Silver Cliff mill started. and in its
| performance disaI pointed the company and all
who were interested in the chloride mines of this
| camp, persons at a distance. knowing little
about the character of the except that they
different from those found elsewhere in the
| United States, and remembering that that
| were shipped away rom Silver Cliff had been re-
| duced in smelters without trouble, jumped to the |
conclusion that the process of milling and raw |
| amagamaton employed by that company not
one adapted to the ores. and that smclter odght
| to have been built instead of stamp mill
No greater mistake was ever made To smelt |
these chloride ores by themselves would cost more
| t1,n tha hest of Them overaOe tn Weld ,yithnut