Tonopah bonanza. [volume] (Butler City [i.e. Butler], Nev.) 1901-1909, 1908-08-29
SILVER METHODS ARE
VERY MUCH IMPROVED

The remarkable advance during
the last few years in the treatment Of
silver ore in Mexico says w. A.
Caldecott in the New York CONNER
cial, may be largely attributed to
the replacement Of the old and costly
patio process by cyanide treatment
preceded by very fine crushing, to
railway development and to water
power installations, which provide
electric power cheaply for remote
mines, where the cost of fuel would
be prohibitive. Power is now being
transmitted up to 10 miles, and
supplied at sos a horsepower q
month, or considerably less than the
average cost of electric power on the
Rand.
THE patio process, invented at
Pachuca by Bartolome de Medina in
1857, nearly a century before Van
Riebeek landed at the cape, is still in
operation at the same mine in that
district, but is now mainly of his
torical interest. The wretched con-
dition of the mules at present en-
ployed in working it, in place of the
men who used to tread the torta,
makes its disappearance less regret-
table than II animals had been re-
placed by the efficient mechanical
digging appliances which have been
invented for the purpose.
"The process of cyanide teaching
preceded by a chloridizing roast is
also now a thing of the past, and
much of the same applies to hypo-
sulphite l%ixiviation.
"The pioneer work of Charles
Buffers is indissolubly associated
with the advance in Mexican cyanid-
ing and fine grinding practice, while
the FL Orc company is famous
throughout the mining world for its
enterprise in developing m%etallurgi-
cal methods. But apart from these
well known mines, the results of the
skill and energy of our fellow-work-
ers in charge Of various ore reduc-
ton plants are obvious in every min
ing district. While these last are
without the great advantage of the
cumulative experience and resources
of the group organization, this is in
some measure Offset by the judicious
foresight of individual companies in
providing means for carrying on ex-
~tensive experimental work. and also
adequate plants for handling the ore
under routine working conditions.
"The average Mexican silver ore is
usually a hard fiinty quartz contain
ing little extraneous base metal min
eral. The bulk of the silver exists in
the for moi sulphide, associated at
times with a little arsenic or anti
mony, while occasionally silver chlOr-
ide and native silver occur A small
percentage Of gold is found with the
silver and constitutes a considerable
proportion Of the bullion value. As
a rule the gold Is extracted during
cyanide treatment a good deal more
readily than the silver, so that spec
ial attention during treatment is not
paid to it. Manganese Is occasional
ly found associated with silver ore.
and is reported to exercise a detri-
mental effect on the extraction.
1.-THE essential features of present
day treatment of silver ore In Mexi;
co consist in very fine crushing with
cyanide solution, treating the bulk Of
the resultant pulp as a slime by de-
cantation. followed by mechanical
altering and zi~nc-shaving precipita.
tion of the solution. While the fore.
going broad statement may be taker
as correct, there exists, as Is natural
ly the case with a progressive art.
considerable diversity Of opinion
among competent operators as to the
advisability of many details of prac
tice, and hence the following more
detailed description must be consid.
cred as universally applicable.
1.-THE fine state of division and un.
form distribution Of the precious
metals in the ore render finer crush.
ing necessary than in common prac.
tice on the Rand, but the means
adopted for this purpose naturally
vary with the existing equipment Of
mills and with the views OF those IN
charge"