A NEW OR IMPROVED PROCESS FOR TREATING SULPHO-ARSENICAL SULPHO- ANTIMONIAL AND TELLURIDE ORES FOR THE EXTRACTION OF GOLD, SILVER
Year: 1882

page_text: LETTERS PATENT to Walter Alfred Barlow of 6 St. Pauls Churchyard
in the city of London Patent Agent and Engineer for an invention of
A NEW OR IMPROVED PROCESS FOR TREATING SULPHO-ARSENICAL SULPHO-
ANTIMONIAL AND TELLURIDE ORES FOR THE EXTRACTION OF GOLD, SILVER
A communication from abroad by Charles de
AND RESIDUAL MATTERS
Vaureal of Paris France.
PROVISIONAL SPECIFICATION left by the said Walter Alfred Barlow at
the Office of the Commissioners of Patents on the 23rd February 1882.
Walter AlfreD BARLOW of 6 St. Pauls Churchyard in the city of London
Patent Agent and Engineer. "A NEW OR IMPROVED PROCESS FOR TREATING
SULPHO-ARSENICAL, SULPHO-ANTIMONIAL AND TELLURIDE ORES FOR THE EXTRAC-
TION OF GOLD SILVER AND RESIDUAL MATTERS A communication from abroad
by Charles de Vaureal of Paris France.
This Invention relates to a new or improved process for treating sulpho-arsenical
sulpho-antimonial and telluride or complex ores for the extraction therefrom of
gold silver and residual matters.
The chief object of this process is the treatment of the above named complex
ores.
In treating these ores by amalgamation as is well known, there is an important
loss of the gold and silver which they actually contain. For a great number of these
ores, especially for such as are poor and possess a refactory gangue the treatinent
by the dry method is impossible.
This improved process which resembles in some respects the treatment by the wet
method has an undoubted superiority over all processes hitherto known, both on
account of the complete extraction of the precious metals and on account of its
economical results in working. For the sake of greater clearness and precision in
the description of the process, I divide it into two parts. In the first part the
object of the treatment is (1) the extraction of the Gold (2) the olimination of
the arsenic and of the antimony.

page_text: In the second part the treatment consists essentially in the extraction of the
Copper and of tho silver; the residual matters being treated for as may be desirable.
The ore is pulvarised sufficiently fine to pass through a sieve of from 40 to 60
mesh.
Mixture. Having determined by analyses the precise quantity of arsenic and of
antimony in the ore I mix with the ore thus powdered an equivalent quantity of
tetra-sulphide of sodium (tetra sulfure de sodium). By an equivalent quantity I
mean the quantity that by calculation I find to be sufficient to transform the sul-
phides of arsenic and of antimony contained in the ore into sulpho-arsenite of
sodium and sulpho-antimoniate of sodium
Calcination. I introduce the mixture thus carefully prepared into a gas retort
heated to a dark red heat,
The proper duration of the calcination must be ascertained by assays made from
time to time upon the mass.
When the calcination is completed the ore is discharged and immediately
plunged into a recipient containing water, without coming into contact with the
outer air.
Lixiviation. The lixiviation is effected methodically with warm water holding in
• solution a quantity of polysulphide of sodium equal to one half of the quantity
which was previously employed in the calcination of the ore.
Extraction of Gold. After these washings the liquid contains all the soluble
sulphosalts and the sulphurate of sodium if the ore contained any gold When the
ore contains gold the liquid is run off and passed through a small filter made from
a mixture of fine sand and of pulverised antimony. At proper times the filter is
changed and its contents are treated for the extraction of the gold from them.
Extraction of antimony The liquid is evaporated to dryness. The sulpho-
antimoniate of sodium (schlippes salt) thus obtained is reduced by scrap or old iron
at a red heat.
The metallic antimony thus obtained is of good quality. During this operation
there has been a formation of double sulphide of iron and sodium which is treated
by moist air and carbonic acid and under the influence of their combined attack it
is decomposod and corbonate of sodium is produced.
As sulphate of sodium has been used in the beginning to form the polysulphide
of sodium the production of carbonate of sodium which has a higher commercial
value must be taken into account in estimating the economical features of the
process, as must also and especially the value of the antimony extracted from the
schlippes salt (sel de schlippe.)
In the second part. The residue of the lixiviation which contains no antimony
or only an infinitesimal quantity is roasted at a low temperature in order to convert
the sulphides into sulphates. The roasted ore is first subjected to a lixiviation with
water to which has been added two or three thousandths by weight of the ore, of
chloride of sodium. The sulphate of silver which was formed is converted into
chloride of silver which is insoluble while the sulphate of copper the sulphate of
iron and the sulphate of zinc are dissolved.
After this first lixiviation I dissolve the chloride of silver by the chloride of
magnesium. The great solvent power of this chloride permits the use of but a very
small quantity of liquid.
Forasmuch as this dissolution of the chloride of silver by the chloride of magnesium
is the interesting peculiarity of this second part of the process, it is not necessary
for me to describe the known steps by which the copper and the silver are
obtained.
I would however especially observe that in consequence of the dimination of the
arsenic and of the antimony I obtain all the silver contained in the ore and this
for the reason that none of it is retained in the form of antimoniate and of arseniate
of silver both of which are insoluble.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter Alfred Barlow in the Great Seal Patent Office on the
23rd August 1882.
WALTER ALFRED BARLOW of 0 St. Paul's Churchyard in the city of London
Patent Agent and Engineer. A NEW OR IMPROVED PROCESS FOR TREATING
"
SULPHO-ARSENICAL SULPHO-ANTIMONIAL AND TELLURIDE ORES FOR THE EXTRAC-
TION OF GOLD SILVER AND RESIDUAL MATTERS A communication from abroad
by Charles de Vaureal of Paris France.
This invention relates to a new or improved process for treating sulpho-arsenical
sulpho-antimonial and telluride or complex ores for the extraction of gold silver and
residual matters.
The chief object of this process is the treatment of the above named complex
ores.
In treating these ores by amalgamation there is an important loss of the precious
metals which they actually contain. For a great number of these ores especially
for such as are poor and have a refractory gangue the treatment by the dry method
is impossible.
This improved process which resembles in some respects the treatment by the
wet method has an undoubted superiority over all processes hitherto known both
on account of the complete extraction of the precious metals which is effected
thereby and on account of its economical results in working.
This process in its entirety comprises the following operations:-1st Pulveriza-
tion-The ore is reduced to powder sufficiently fine to pass through a sieve No 60
that is to say a sieve containing about 3600 holes to the square inch.
2nd Mixture The ore is mixed either during the pulverization or afterwards
with a sufficient quantity of sulphide of sodium to form soluble sulphosalts with
the sulphides of arsenic of antimony of tellurium and of gold which the ore
contains. The necessary proportion of this reagent which must be added will vary
according to the quantity of arsenic, of antimony of tellurium and of gold which
the ore contains.
This proportion may be established in the following manner;
Take of monosulphide of sodium a quantity, the weight of which must be equal
to twice the weight of arsenic and once the weight of metallic antimony and once
the weight of tellurium and once the weight of metallic gold which the ore contains
together with ten per cent of the weight of the gangue of the ore, and if the ore
contains iron there must be added also:-once the weight of metallic iron which
the ore contains; having thus established the weight of the monosulphide of
sodium it is necessary to add a quantity of sulphur equal to one quarter of the
weight of the nonosulphide of sodium but an excess of sulphur has no deleterious
effect.
The mixture of the ore of the monosulphide of sodium and of the sulphur is
carefully prepared so as to present a perfectly homogeneous mass.
3rd Calcination-The mixture is placed in a gas retort made of refractory earth.
This retort is to be provided with a trap door so arranged as to allow of the
introduction of a rake but so as to prevent as far as possible the entrance of air
into the retort, as it is an indispensable condition that the calcination should take
place with exclusion of the air, the retort is hermetically closed save in so far as
it is absolutely necessary for the_introduction of the rake above mentioned and is
heated to a dull red heat.
The mixture in the retort must be frequently stirred with the rake in order that
it be equally beated throughout the entire mass.

page_text: For this purpose it is necessary so to regulate the loading of the retort that the
layer of the mixture in the retort should not be above three or four inches thick.
At the end of three hours it is necessary to commence drawing samples from the
mixture in order to follow the progress of the operation. These samples are
washed with warm water in which a small quantity of sulphide of sodium has been 5
dissolved and by adding to the waters of these washings hydrochloric acid they
give a precipitate of the sulphides of arsenic, antimony and so forth which the ore
contains, and the quantity of this precipitate indicates the progress of the operation
and this will be terminated when the quantity of this precipitate of sulphides of
arsenic, antimony and so forth formed in these waters, corresponds to the quantity 1
of these sulphides contained in the ore as indicated by a previous analysis of the
ore.
The duration of the calcination is generally from threo to six hours.
When from the examination of the samples drawn from the retort, the calcina-
tion that is the action upon the ore appears to be complete the ore is discharged
from the retort and plunged immediately into a current or a bath of water
without coming into contact with the outer air, in order to avoid the decomposition
by the air of the sulphosalts formed during the calcination.
During the calcination the sulphides of arsenic, of antimony, of tellurium and of
gold combine with the sulphide of sodium and form sulpho-arsenite sulpho-
antimoniate, sulpho-tellurite and auro-sulphide of sodium which are all soluble in
water. The sulphides of silver and of copper are not effected or if they are
effected they form double sulphides, and these are decomposed by the action of the
water which separates them into an alkaline sulphide which is soluble and
metallic sulphides which are insoluble.
4th. Lixiviation-The lixiviation takes place first in the cold water which receives
the ore as it is discharged from the retort.
This water removes from the ore a large part of the soluble salts. It is continued
afterwards in warm water at about 80° C. in order to complete the elimination of
the soluble parts. For this second washing it is advisable to dissolve previously in
the water a small quantity of sulphide of sodium and generally the addition to
this water of two to five per cent of sulphide of sodium is sufficient to give the
best results.
As it is desirable to reduce as far as is possible the quantity of water necessary
for the lixiviation, it will be found useful to pass the last waters of one washing
over ore newly calcined.
This lixiviation is terminated when the examination of samples drawn from the
washed ore shows that it contains no more arsenic or antimony or tellurium or
gold.
The waters of the lixiviation then contain in the form of sulpho-arsenite sulpho-
antimoniate, sulpho-tellurite and auro-sulphide of sodium all the arsenic, the
antimony the tellurium and the gold which the ore contained.
5th. Extraction of Gold. When the ore contains gold the waters of the lixi-
viation are passed through a filter made of a mixture of fine sand and of pulverised
metallic antimony. The antimony of the filter precipitates the gold contained in
these waters as cement gold which is mixed with the antimony of the filter. At
proper times the filter is changed and the gold is separated from the antimony by
any of the known processes of metallurgy. I do not claim any especial process
for this separation.
6th. Extraction of arsenic of antimony of tellurium-The waters of the lixi-
viation after the extraction of the gold if the ore contained gold and if not then
immediately after the lixiviation are treated for the extraction of the arsenic of
the antimony and of the tellurium
Ordinary sulphuric acid of commerce is added to these waters and the arsenic
the antimony and the tellurium are precipitated in the form of sulphides.
This precipitate is filtered and these sulphides are collected as such
7th. Regeneration of sulphate of soda.-The waters then remaining after the

page_text: extraction of the above sulphides are then evaporated to dryness. The residue of
this evaporation is sulphate of soda.
The commercial value of this product should be taken into account in estimating
the cost of the process.
The residue of the ore which remain after the lixiviation above described contains,
with the gangue all the sulphides of silver and of copper. These sulphides will
not have been effected by the various operations which the ore has undergone.
The extraction of these metals from the ore can be then made by any process
known in metallurgy. I do not claim for this extraction any special process but I
would call attention to the facts--that the ore has been rendered easier and more
economical for treatment for these metals and that in consequence of the elimination
of the arsenic antimony and tellurium it will yield in silver a larger proportion
than could have been otherwise obtained inasmuch as no silver will be carried off
by arsenic or by antimony or by tellurium, and it will yield in copper a metal
of a quality superior to that which could have been otherwise obtained from
the ore.
Having thus described the process at length I claim as new this process the
object of which is to extract gold antimony arsenic and tellurium from sulpho-
antimonial sulpho-arsenical and telluride ores and to render the treatment of these
ores for the extraction of silver and of copper easier inore economical and more
advantageous in increasing their yield in silver and in improving the quality of the
copper obtained.
It is to be understood then that this process consists in the following operations
in the order stated.
1st. Pulverization of the ore.
2nd. Mixture of the pulverized ore with sulphide of sodium and with sulphur in
the proportions given and in the manner described.
3rd. Calcination of the mixture without contact with the air in the manner
described.
4th. Discharge of the calcinated ore into water without contact with the air in
the manner described.
5th. Washing of the calcinated ore first in cold water and then in warm water
slightly charged with sulphide of sodium all in the manner described.
6th. Precipitation of the gold by metallic antimony in the manner described.
7th. Precipitation of the sulphides of arsenic antimony and tellurium by sulphuric
acid in the manner described.
8th. Regeneration as sulphate of soda of the soda contained in the sulphide of
sodium employed as set forth.
And while I claim this process as a whole and in the order above described as
new I also claim as new the third and fourth operations as hereinbefore set forth
but the other six operations in themselves and taken separately or apart from the
others I do not lay claim to as new.
In witness whereof I the said Walter Alfred Barlow have hereunto set my
hand and seal this twenty first day of August in the year of our Lord
one thousand eight hundred and eighty-two.
WALTER A. BARLOW. (L.S.)