The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1899-08-01
THE PATIO PROCESS.
One-Half of Mexico's Silver Product Has
Been Obtained by 1t.

In an article written for the En-
cheering and Mining Review of San
Francisco, E. j. Molera, c. E. and M.
F., describes the patio process as fol-
lows:
The patio process consists of first
grinding the ores to a very fine powder
by means of large cylindrical stones
somewhat like huge grinding stones,
which, rolling over the ore, grind it,
mixed with water, into a fine pulp The
apparatus which produces this result
is called the "tahona." After this Is
done the mass of wet ore, like an enor-
nous mud pie, is taken to the patio, q
large yard, generally enclosed by walls
and paved with stone. Spread over the
cake is mixed with about or per
cent. of salt and is left in that state
for several days. After that the mag
istral' is prepared; this consists of q
mixture of oxide of iron and sulphate
of copper, which is generally obtained
by grinding pyrites of copper to a fine
powder. About / or IL per cent. of
ma gistral is added to the ore.
After the magistral has been intro
duced into the torta or cake, quicksilver
in small amounts is added to the mass
The quantity of quicksilver varies with
the richness of the ore; generally
about six or eight parts of mercury to
one part of silver. When the quick
silver has been added horses are made
to tramp over the mass with the object
of mixing well and to divide the whole
The 'headman" of the patio takes
from time to time a small amount of
the mixture and with his fingers rubs
it. If it looks gray and comes together
easily, making paste, then the work Is
being done well. If the quicksilver is
seen in small globules and Of a dark
color, then there is too much magistral
in the torta, or, as the miners call it,
1t is too warm: 1t is necessary then to
add some lime to cool it. If the mer-
curry is clean and shining and shows
itself in large amounts, then the torta
is cold and more magistral has to be
added.
After some days, when taking some
of the stuff and washing it with water,
it will be found very finely divided like
powder, and with the appearance of sill
Yer filings. Then some more quicksil-
YER is introduced. When it is thought
that the amalgamation is complete, a
little more quicksilver is added, and
the horses are kept tramping for three
or four hours, when the pulp is gathered
and the hose played on 1t. until all the
shines are washed away and only the
amalgam remains: then the amalgam
is strained through cloth and after
wards distilled.
The theory of the patio process is as
follows: The sulphate of copper, in
presence of salt, is transformed into BIZ
chloride of copper: this compound re-
acts on the silver sulphurates and
changes them into silver chlorides, and
is itself changed into copper sulphurate.
The silver chlorides, dissolved in the
liquor which contains sodium chloride.
produces double salt which is easily
reduced by the quicksilver. Santa go
Ramirez. a mining engineer from Min
eral del Orc. Mexico, has given an cleo
tro- chemical theory of the patio process
which shows great ingenuity and no
doubt explains some of the phenomena
of it's workings otherwise unexplained.