Improved Process and Apparatus for Extracting Gold from Ores and other Auriferous Substances.
Year: 1895

page_text: Date of Application, 10th Sept., 1895-Accepted. 21st Dec., 1895
COMPLETE SPECIFICATION.
Improved Process and Apparatus for Extracting Gold from Ores and
other Auriferous Substances.
I, BERTRAND CHASE HINMAN, of No. 22 Cliff Street, New York City, New
York, United States of America, Chemist, do hereby declare the nature of
this invention, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
In the extraction of gold from ores and other auriferous substances by bromine,
a larger quantity of bromine must be employed than is necessary to combine with
the gold. There are always present in the ore many other elements which combine
with the bromine so that the use of an excess of this element becomes imperative
to completely extract the gold. An excess of bromine attacks and dissolves the
gold very quickly and this is an important feature in the treatment of gold bearing
ores. Unless, therefore, means are provided to prevent the loss of the bromine and
to regenerate it from its combinations, the process would become too expensive and
therefore practically prohibitive.
The object of my invention is to extract the gold from ores by the use of an
excess of bromine and to regenerate the bromine.
In the accompanying drawing:
Fig. 1 is an elevation, partly in section, of an apparatus for carrying my invention
into effect.
Fig. 2 is a similar view of a modification.
The pulverized ore is mixed with water and is thrown into a revolving cylinder a.
I then add from three to twenty pounds of bromine to each tou of ore, or so much
as may be necessary to speedily dissolve the gold. The water is added for the
purpose of obtaining a strong aqueous solution of bromine that permeates through
the whole mass of the ore and reaches the particles of gold contained therein.
When the gold is so dissolved it must be leached out by a second solution in order to
separate the dissolved gold from the ore. For this second leaching solution I prefer
to use water charged with one or more of the halogens (excepting fluorine) which
prevents the possibility of the gold being precipitated in the ore.
The leached and
filtered solution is run through a pipe b, into a separating tank or still
which can
be hermetically closed. A pipe d, leads from the top of the tank c, to a condenser e,
which is filled with cold water or other cooling medium. The contents of the tank c,
are now heated to such a temperature that the bromine distils over as vapor through
pipe d, into the condenser e. Here these bromine vapors are condensed into liquid
bromine which is collected in receiver f.
C,
The heat by which the distillation is effected may be applied in any suitable way,
such as an open fire, or immersed steam or hot air pipes. I prefer, however, to use
live steam which is injected directly into the liquid from a suitable generator /,
through a pipe g, which opens into tank c, below the surface of the liquid. By the
use of the live steam the solution is not only quickly raised to the distilling
point of the bromine, but the separation of the bromine is also mechanically greatly
expedited.
If other elements have been present in the ore with which the bromine has
combined, the solution in tank c, will contain such of them as are soluble in water.
To set the bromine free from these combinations, I introduce chlorine through
pipe i, from cylinder j, or the chlorine may be directly generated in the tank. The
hlorine may be admitted simultaneously with the steam and will displace the
bromine from its combinations. Or I may introduce into the solution or produce
uit any other oxidizing agent sufficiently powerful to set free the bromine from

page_text: its combinations. Such an oxidizing action will be produced for instance by the
use of potassium permanganate and an acid. The liberated bromine vapors are o
course carried through the condenser and collected in the receiver f. In some
instances it may be desirable to introduce the liberating re-agents directly
into the cylinder with the ore, which will prevent the formation of the bromide
salts.
After all the bromine vapors have been expelled from the tank c, and
condensed, the steam is turned off and the gold solution is allowed to run through
tap k, into a precipitating tank 1, where the gold may be precipitated in any
manner.
e,
If desired, the cylinder a, may be directly connected with the condenser and
with the steam and chlorine pipes. In this case the cylinder a, will itself constitute
the still, and the tank c, may be dispensed with.
In the modification illustrated in Fig. 2, the bromine is recovered by driving air
through the body of the liquid in the tank c. The compressed air is introduced
into the tank from compressor m, through pipe n. The air will drive out the
bromine through pipe o, into a tank or vessel p, containing an alkaline hydrate
capable of absorbing the bromine.
Bromide and bromate salts are thereby formed from which the bromine may be
recovered in any suitable manner.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. The process of extracting gold from ore which consists in dissolving the gold
by bromine, separating the free bromine from the solution, recovering the bromine
and then precipitating the gold, substantially as specified.
2. The process of extracting gold from ore which consists in dissolving the gold
by bromine, distilling the free bromine, condensing the bromine vapors and
precipitating the gold, substantially as specified.
3. The process of extracting gold from ore which consists in dissolving the gold
by bromine, distilling the free bromine by steam, condensing the bromine vapors and
precipitating the gold, substantially as specified.
4. The process of extracting gold from ore which consists in dissolving the gold,
by bromine, foreing steam into the solution beneath the surface thereof, to vaporize
the bromine and charge the steam with such vapors, driving the charged steam into
a condenser to liquefy both the steam and bromine, and precipitating the gold,
substantially as specified.
5. The process of extracting gold from ore which consists in dissolving the gold
by bromine, driving the free bromine in the form of vapors out of the body of the
solution by the action of compressed air and into an alkaline solution to form a salt,
regenerating the bromine from such salt, and precipitating the gold, substantially as
specified.
6. The process of extracting gold from ore which consists in dissolving the gold
by bromine, adding an oxidizing agent, to liberate the bromine from the combinations
formed during the treatment of the ore, separating the liberated bromine, recovering
the same, and precipitating the gold, substantially as specified.
7.. In the process of extracting gold from ore, a leaching solution charged with one
or more of the halogens, substantially as specified.
8. An apparatus for extracting gold from ore which consists of a vaporizing
tank, a vapor outlet pipe and a condenser or regenerating tank, substantially as
specified.
9. The process of extracting gold from ore, substantially as herein described.
Dated this Twenty-first day of June 1805