Copper, and other Metals or Useful Compounds thereof.
Year: 1887

page_text: Date of Application, 19th May, 1887
Complete Left, 17th Feb., 1888
Complete Accepted, 23rd Mar., 1888
Copper, and other Metals or Useful Compounds thereof.
We, JOHN STEWART MAC ARTHUR, of 15 Princes Street, Pollokshields, in the
County of Renfrew, North Britain, Metallurgist, ROBERT WARDROP Forrest, M.D.,
and WILLIAM FORREST, M.B., both of 319 Crown Street, Glasgow, in the County of
Lanark, North Britain, do hereby declare the nature of this Invention to be as follows,
that is to say :-
This Invention comprises improved processes or a combination of processes which
whilst applicable to various ores is suitable for the treatment of complex ores and ores
which cannot be very satisfactorily treated by previously known processes.
The ores to be treated by this Invention may be such as contain all or any of the
metals, lead, zinc, iron, copper, gold, silver, and other metals; and the Invention is
especially applicable when the ores are in the form of or comprise pyrites, mundic, or
sulphurets.
In carrying out the Invention the first stage consists in treating the ore in a state
of fine division with a persalt or mixture of persalts of iron (such as perchloride or
persulphate) in solution and at a suitable temperature, and under pressure if necessary.
This solution (of perchloride of iron for example) acts by dissolving some of the
metals, chiefly copper, zinc, lead, and silver as corresponding salts (chlorides). As
salts of lead are generally only sparingly soluble in cold water it is advisable to wash
them out with hot water; and likewise a hot strong solution of common salt or other
suitable solvent should be used for washing out silver salts.
The solution of iron which has become wholly or partly reduced to a protosalt is
drawn off and allowed to cool (if necessary) and settle in the first of a series of tanks,
and afterwards in the other tanks of the series in order. The most of the lead and
silver will settle in the first two or three of the tanks, or the settling may be
accelerated by the addition of a suitable precipitant such as an iodido. When the
most part of the lead and silver has been thrown down, the solution is run into the
next tank or tanks and the copper is precipitated by means of metallic iron, sulphide
of sodium or other convenient agent.
The solution freed from copper is run into other tanks and the zinc is precipitated
by adding oxide of zinc, sulphide of sodium or other convenient agent. If sulphide
of sodium or other alkaline sulphide is used, a quantity not more than sufficient for
precipitating the zinc or rather a little less should be used, or if nickel and cobalt
are present, a quantity rather less than what corresponds to the three metals together
should be used.

page_text: The washings which follow the original solution are to be similarly treated
according to the quantity and variety of metals they contain.
The protosalt of iron which is now the principal substance left in solution, is to be
regenerated for further use by any of the known oxidising processes, for example, by
injecting air or chlorine; in many cases, however, it will be best to regenerate the
liquor by running it into the anode compartment of an electrolysing tank common
salt or other suitable compound or compounds if not already present, being added to
both the anode and cathode compartments. When an electric current is passed
through the tank the protosalt will become a persalt again ready for further use.
If copper, lead, zinc, silver, and other metals are present in the ore in small
quantities only it will not be necessary to separate them each time the iron solution'
is used. They do not interfere with the regeneration of the solution; and may be
allowed to accumulate until in quantities convenient for being separated.
In the second stage of the treatment of the ores, that is after removing the copper,
lead, zinc, silver, and other similarly separable metals, the ores may be treated with
chlorine, bromine, or iodine in a solution also containing salts which will not to any
material extent absorb the chlorine, bromine, or iodine, nor precipitate gold from
solution but will prevent base metals and pyrites from dissolving, as described in the
Provisional Specification relative to the Application for a patent, No. 11817 of 1886.
Or the ores may be treated according to a modification of that process with a quantity
of perchloride, perbromide, or periodide of iron, or with any suitable mixture of a
persalt of iron with a chloride, bromide, or iodide with the aid of heat and pressure
if required. The gold which is obtained in solution may be precipitated by any
suitable known means, such as treatment with sulphuretted hydrogen, protosulphate
of iron, or electrolysis, and the chlorine, bromine, or iodine may also be regenerated
by known methods such as treatment with with bleaching powder and an acid or with
a bichromate and an acid or electrolysis.
In many cases it may be found advisable to further purify the ore before treating
it to extract the gold. For this purpose when required we use the solution of soda
or other alkali or alkaline earth found in the cathode compartment of the electrolysing
tank. A suitable temperature with pressure if necessary is employed in this treatment
which yields a variety of salts corresponding to the constituents of the ores and to
the particular alkali or alkaline earth used. The solution obtained is to be treated
according to its composition for the separation of any of its ingredients which may be
useful or valuable.
The addition of a suitable quantity of a solution of the metallic salts, such as those
of lead, zinc, copper, or silver, formed during the first stage of the process, or even
of a salt of iron, will precipitate the arsenic, antimony, and part of the sulphur, leaving
hyposulphites and thiosulphates in solution. This remaining solution may be used
very advantageously in washing out the salts of silver instead of common salt, the
silver being subsequently precipitated therefrom by means of zinc, copper, or sulphide
of sodium or of other alkali or alkaline earth, the treatment last indicated serving to
regenerate the hyposulphite and thiosulphate solution.
The actions hereinbefore described are not all absolutely distinct or completely
confined each to one result, as, for example, a little gold may be got along with the
silver or vice versû; the actions and results are however substantially distinct and
sufficiently so for practical purposes.
When any of the metals is separated as an oxide or salt it is not necessary in every
case to reduce it to the metallic state, as it will in some cases be more convenient and
profitable either to dispose of it as an oxide or salt, or to directly convert it into some
useful product such as white lead, or zinc-white, or rouge, or a pigment such conversion
being effected by well known processes.
Dated this Eighteenth day of May 1887
EDMUND HUNT,
Applicants' Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in Treating Ores to Obtain Gold, Silver, Lead, Zinc,
Copper, and other Metals or Useful Compounds thereof.
We, JOHN STEWART MAC ARTHUR, of 15 Princes Street, Pollokshields, in the
County of Renfrew, North Britain, Metallurgist, ROBERT WARDROP FORREST, M.D.,
and WILLIAM FORREST, M.B., both of 319 Crown Street, Glasgow, in the County of
Lanark, North Britain, do hereby declare the nature of this invention and in what
manner the same is to bo performed, to be particularly described and ascertained
in and by the following statement, that is to say :-
This Invention comprises improved processes or a combination of processes which
whilst applicable to various ores is suitable for the treatment of complex ores and
ores which cannot be very satisfactorily treated by previously known processes.
The ores to be treated by the Invention may be such as contain all or any of the
metals lead, zinc, iron, copper, gold, silver, and other metals; and the Invention is
especially applicable when the ores are in the form of, or comprise pyrites, mundic,
or sulphurets.
In carrying out the Invention the ore having been reduced to a state of fine
division in any suitable known manner, is first treated with a persalt or mixture of
persalts of iron (such as perchloride or persulphate) in solution and at a suitable
temperature and under pressure if necessary. The temperature which is believed to
give the best results is that at which the solution boils in each case; at a lower
temperature longer time is required. The solution (of perchloride of iron for example)
acts by dissolving some of the metals, chiefly copper, zinc, lead, and silver, as corre-
sponding salts (chlorides) and these salts are separated from the other matters by
washing. If lead is present in the ore it is advisable to use hot water to wash out its
salts, or any of the solvents known to have the desired action; and if silver is present
a hot strong solution of common salt or other suitable solvent should be used for
washing out its salts.
The persalt of iron used in treating the ore as described becomes wholly or partly
reduced to protosalt. The solution is drawn off and allowed to cool (if necessary)
and to settle in the first of a series of tanks, and afterwards in the other tanks of the
series, in order. The most of the lead salt and silver salt will settle in the first two
or three of the tanks, or the settling may be accelerated by the addition of a suitable
precipitant such as an iodide. When the most part of the lead salt and silver salt
has been thrown down, the solution is run into the next tank or tanks, and the copper,
if present, is precipitated by means of metallic iron, or sulphide of sodium or other
convenient agent.
The solution having been freed from copper is next run into other tanks and the
zinc is precipitated by adding oxide of zinc, or sulphide of sodium, or other convenient
agent. If sulphide of sodiuin or other alkaline sulphide is used, a quantity not more

page_text: than sufficient for precipitating the zinc, or rather a little less should be used, or if
nickel and cobalt are present, a quantity rather less than what corresponds to the three
metals together should be used.
The washings which follow the original solution are to be similarly treated
according to the quantity and variety of metals they contain.
The protosalt of iron which is the principal substance left in the solution, is
regenerated for further use by any of the known oxidising or chloridising processes,
for example, by injecting air or chlorine, acid being added if necessary. In many
cases, however, it will be best to regenerate the liquor by running it into the anode
compartment of an electrolysing tank, common salt or other suitable compound or
compounds, if not already present, being added to both the anode and cathode com-
partments. When an electric current is passed through the tank the protosalt of iron
will become a persalt again ready for further use.
If copper, lead, zinc, silver, and other metals are present in the ore in small
quantities only, it will not be necessary to separate them each time the iron solution
is used. They do not interfere with the regeneration of the solution, and may be
allowed to accumulate until in quantities convenient for being separated..
In the second stage of the treatment of the ore, that is after dissolving and
wasbing out the copper, lead, zinc, silver, and other similarly separable metals in the
manner hereinbefore described, the ores may be treated as described in the Complete
Specification of Patent No. 11817 of 1886, that is to say, the ores may be treated
with chlorine, bromine, or iodine, in a solution also containing salts which will not to
any material extent absorb the chlorine, bromine, or iodine, nor precipitate gold from
solution, but will prevent base metals and pyrites or mundic from dissolving. Or, as
we now prefer, the ore is treated with a solution containing perchloride, perbromide,
or periodide of iron, or any mixture of a persalt of iron with a chloride, bromide, or
iodide, heat and pressure being used if required. If gold is present it will be obtained
in solution as a salt, provided a sufficiently large excess of the perchloride, per-
bromide, or periodide is present, and may be precipitated by any suitable known
means, such as treatment with sulphuretted hydrogen, or protosulphate of iron, or by
electrolysis, and the chlorine, bromine, or iodine, may also be regenerated by known
methods, such as treatment with bleaching powder and an acid, or with a bichromate
and an acid, or by electrolysis.
In many cases it is advisable to further purify the ore before treating it to extract
the gold. For this purpose we may use the solution of soda or other alkali or alkaline
earth formed in the cathode compartment of the electrolysing tank. A suitable
temperature with pressure if necessary is employed in this treatment, which yields a
variety of salts corresponding to the constituents of the ore, and to the particular
alkali or alkaline earth used. Tho solution obtained is to be treated according to
its composition for the separation of any of its ingredients which may be useful or
valuable.
be
The addition of a suitable quantity of a solution of the metallic salts, such as those
of lead, zinc, copper, or silver, formed during the first stage of the process, or even
of a salt of iron, will precipitate arsenic, antimony, and part of any sulphur present,
leaving hyposulphites and thiosulphates in solution. This remaining solution may
used very advantageously in washing out the salts of silver instead of a solution of
common salt, the silver being subsequently precipitated therefrom by means of zinc,
or copper, or sulphide of sodium or of other alkali or alkaline cartlı, the treatment
last indicated serving to regenerate the hyposulphites and thiosulphates in the
solution.
The actions herein before described are not all absolutely distinct or completely
confined each to one result, as-for example-a little gold may be got along with the
silver, or vice versu; the actions and results are, however, substantially distinct and
sufficiently so for practical purposes.
When any of the metals is separated as an oxide or salt, it is not necessary in every
case to reduce it to the metallic state, as it will in some cases be more convenient and
profitable either to dispose of it as an oxide or salt, or to directly convert it into some

page_text: useful product, such as white-lead, or zinc-white, or rouge, or a pigment, such
conversion being effected by well known processes.
Having now particularly described and ascertained the nature of our said Inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The combination of processes for treating ores according to which firstly,
copper, lead, zinc, silver, and other similarly separable metals or such of them as are
present in the ores, are converted into soluble salts by treating the ores with a persalt
of iron in solution and are separated in solution; and secondly gold is converted into
a soluble salt by treating the remainder of the ores with a solution of soda or other
alkali or alkaline earth and subsequently with perchloride, perbromide, or periodide
of iron substantially as herein before described.
2. The combination of processes for treating ores according to which firstly,
copper, lead, zinc, silver, and other similarly separable metals or such of them as are
present in the ores, are converted into soluble salts by treating the ores with a persalt
of iron in solution and are separated in solution; and secondly gold is converted into
a soluble salt by treating the remainder of the ores with perchloride, perbromide, or
periodide of iron substantially as hereinbefore described.
3. The combination of processes for treating ores, according to which, firstly,
copper, lead, zinc, silver, and other similarly separable metals, or such of them as are
present in the ores, are converted, into soluble salts by treating the ores with a persalt
of iron in solution and are separated in solution; and secondly, the remainder of the
ores is treated with chlorine, bromine, or iodine, in a solution also containing salts
which will not to any material extent absorb the chlorine, bromine, or iodine, nor
precipitate gold from solution, but will provent base metals and pyrites or mundic
from dissolving, the processes being conducted substantially as hereinbefore
described.
EDMUND HUNT,
Applicants' Agent.