AN IMPROVED PROCESS AND APPARATUS FOR CHLORINATING GOLD, SILVER, AND COPPER ORES
Year: 1870

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine,
Lake, & Co., Southampton Buildings, London, Patent Agents,
for the Invention of "AN IMPROVED PROCESS AND APPARATUS FOR
CHLORINATING GOLD, SILVER, AND COPPER ORES."-A communication
from abroad by Charles Stetefeldt, of Austin, Nevada, United States
of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 30th June 1870, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Southampton
Buildings, London, Patent Agents, send greeting.
WHEREAS I am in possession of an Invention for "AN IMPROVED
PROCESS AND APPARATUS FOR CHLORINATING GOLD, SILVER, AND COPPER ORES,"
and have petitioned Her Majesty to grant unto me, my executors,
administrators, and assigns, Her Royal Letters Patent for the same, and
have made solemn Declaration that it has been communicated to me

page_text: America.
NOW KNOW YE, that I, the said William Robert Lake, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed, in and by the fol-
lowing statement, reference being had to the accompanying Drawing
forming a part of this Specification :-
My Invention consists in dropping a mixture of pulverized ore and
salt through a vertical or nearly vertical shaft, through which the
products of combustion are ascending, whereby an almost instantaneous
chlorination of the ore is effected which leaves silver ores ready for
amalgamation or lixiviation, prepares copper ores for lixiviation and sets
the gold in gold sulphurets free for amalgamation. I take any ore and
mix it with from one to eight per cent. or more of its weight of common
salt, more or less, according to the character of the ore, after which I
pulverize the mixture to the degree of fineness commonly required to
prepare ore for amalgamation or lixiviation, I then introduce this mixture
into the top of a furnace, the shaft of which is vertical or nearly so, and
which is heated by fire-places at or near the bottom, so that a current
of heated air, gases, and other products of combustion is continually
ascending through the shaft. Care must be taken to introduce the mix-
ture so that it shall fall in separate and finely divided particles and not
in lumps. As the pulverized mixture falls through the current which
rises from the fire the ore and salt are both instantly decomposed, the
action of the heat separating the silver, copper, and gold from the sulphur,
antimony, or other substance combined or mixed with it, and the salt
being also at the same time decomposed by the gases which are formed
by the decomposition of the ore. The chlorine of the salt then instantly
unites with the silver and copper, and partly with the gold, so that the
chlorination of the ore is completed, while the ore falls down the shaft.
The chlorination of the silver is not so perfect. With proper care as
much as ninety-six per cent. is changed to chloride of silver. The gold
is chloridised in the upper part of the shaft, but in the lower part the
chloride of gold is again decomposed, and metallic gold formed which,
however, amalgamates much better than if the ore had been roasted
without salt. In case copper ores are treated by this process the tem-
perature must be kept low. As a large part of the copper is in the

page_text: shape of the chloride Cu, Cl, which is insoluble in water, the ore has
to be washed with acidulated water. This can be easily obtained by
the process itself. The gases in escaping from the furnace are highly
charged with hydrochloric acid, which can be condensed in water and
used for the purpose
indicated.
The said Invention further consists in an improved furnace for roast-
ing and treating ores in a finely pulverized state. This furnace is con-
structed with a shaft heated by fire plates near the lower end, the fall of
the ore through which is retarded by the upward motion of the heated
air and gases, and a flue leaving the shaft near the upper end, which is
heated by a separate fire-place. The flame or heated air passing up the
shaft heats the particles of the falling ore, and effects their perfect
desulphurization or chlorination, which latter takes place in case the
ore pulp has been mixed with salt. As the ore has to be pulverized very
fine, that is to say, so fine that it will pass through a wire screen with
forty holes per
linear inch, a part of the ore will necessarily be carried
by the draft through the flue near the top of the furnace. To effect
a perfect roasting of this part of the ore a fire-place is connected with
the fluc, through the flame of which the ore has to pass. Between the
flue and chimney a system of large chambers is arranged to allow the
Just to cattle
Figure 1 is a section on the line A, A; Figure 2 is a section on the
line C, C; Figure 3 is a section on the line B, B.
D represents the shaft of the furnace covered at the top with proper
machinery for feeding the ore as follows:-A hollow cast-iron frame
kept cool by a small stream of water rests on top of the furnace. In
this frame is inserted a cast iron grate, which is covered by a punched
screen of Russia iron No. 0, for wet crushing. Close to the punched
screen moves inside of the hopper a coarse wire screen, No. 3, which is
fastened to a frame. The frame has flanches resting upon adjustable
friction rollers outside of the hopper, and receives its motion from a
crank with 1%, inch excentricity. To avoid the motion of a stratum of
pulp with the coarse screen a number of thin iron blades is so arranged
across the hopper that their lower edges reach close down to the coarse
screen and keep the pulp in place. When the crank is set in motion
the meshes of the coarse wire screen cut through the pulp and drive it

page_text: through the openings of the punched screen. In this way the ore is
introduced in a continuous stream into the furnace. E, E, are the fire-
places near the lower end of the shaft, from which the flame and gases
pass up the shaft and through the flue F into the dust chambers. G is
the fire-place for heating the lower part of the flue F, where the fine
dust is roasted. In the lower part H of the shaft D the roasted ore
accumulates and is discharged through the door I. The larger part of
the dust accumulates at H, and is discharged through the doors L. The
operation of my furnace is as follows:-Fire is made in the fire-
places E, E, and G, and as soon as the furnace is hot the feeding machine
is put in motion. The only attention which the furnace requires is the
keeping up of a regular roasting heat, which has to be varied according
to the nature of the ore treated. The ore is discharged through the
door as soon as it accumulates too much.
Having thus fully described the said Invention as communicated to
me by my foreign correspondent, and shown how the same may be
conveniently and advantageously carried into practice, I claim,―
First. The process of chloridizing silver, copper, and gold ores by
dropping a mixture of pulverized ore and salt through a vertical or
nearly vertical shaft through which the products of combustion are
ascending.
Second. The combination of a shaft, vertical or nearly so, with fire-
places at or near the bottom, a flue leading from the upper part of the
shaft, and an auxiliary fire-place for heating said flue for the purpose
described.
Third. The machinery for feeding the oro into the furnace, consisting
of the wire screen and the blades operating as described, either with or
without the punched screen.
In witness whereof, I, the said William Robert Lake, have here-
unto set my hand and seal, the Thirtieth day of June, in the
year of our Lord One thousand eight hundred and seventy.
Witness,
WILLIAM ROBERT LAKE. (L.S.)
D. L. WAGNER.