Improvements in Obtaining Precious Metals from Solutions.
Year: 1895

page_text: Date of Application, 5th Sept., 1895
Complete Specification Left, 4th July, 1896-Accepted, 5th Sept.. 1896
PROVISIONAL SPECIFICATION.
Improvements in Obtaining Precious Metals from Solutions.
I, JOHN STEWART MACARTHUR, of 12 Knowe Terrace, Pollokshields, in the
County of Renfrew, North Britain, Technical Chemist, do hereby declare the
nature of this invention to be as follows:-
My said invention has for its object the obtaining of precious metals from
solutions by improved means which will yield satisfactory results with economy in
cost, time, and labor.
My improvements will be principally applied in dealing with cyanide solutions
obtained from ores and the like; the application of them is not however limited to
such solutions.
In carrying out my invention according to one modification, I obtain or separate
the precious metal from solution by precipitating it by means of an electric current
applied in a vat or box provided with special plates of a kind hereinafter described.
The plates to be used as anodes are of iron or steel and coated with graphite or
other suitable form of carbon. Plates of the same kind may be used as cathodes;
or the cathode plates may consist of iron or steel coated with lead. Or iron or
steel plates coated with lead oxide or other suitable oxide may be employed for
either auodes or cathodes or for both.
The construction of the vat or box and the forms of the plates may be varied,
but in one modification the vat or box is of an elongated form, and is of an
approximately square section internally; and the plates are placed transversely
and are shaped to fit the bottom and sides closely, being supported in grooves or
otherwise. The plates are made with parts extending above the parts to be
immersed, the extensions having holes formed in them and serving as handles and
also to receive conducting bars. Each plate is formed with a notch at a bottom
corner or at an upper corner, and a series of plates is arranged with lower notches
at one side of the vat alteruating with upper notches at the other side. The lower
and upper notches are thus diagonally apart; and the solution admitted at one end
of the vat flows in a general diagonal direction between each plate and the next on
its way to the other end of the vat. The plates are, by preference, placed near
each other, the spaces between them being, for example, about a quarter of an inch
thick and non-conducting buttons or distance pieces may be attached to the
plates, or otherwise applied, so as to keep the plates the desired distance apart.
The electric current may be supplied or distributed to the plates according to
various arrangements, the arrangement chosen in each case depending on the kind
of current employed and other circumstances. Thus the plates may be made
alternately anodes and cathodes; or the plates at the end of a series may be
.connected respectively to the positive and negative poles of the electric source; or
with alternating anode and cathode plates in one vat or series, the cathode plates
may be severally connected to anode plates of a second vat or series, the cathode
plates of which are connected to a negative conductor. Any other suitable known
arrangement of the plates and current connections may be adopted.
Dated this 5th day of September 1895.
ALLISON BROS.,
Agents for the Applicant.

page_text: Improvements in Obtaining Precious Metals from Solutions.
I, JOHN STEWART MACARTHUR, of 12 Knowe Terrace, Pollokshields, in the
County of Renfrew, North Britain, Technical 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 :-
The said invention has for its object the obtaining of precious metals from
solutions by improved means which will yield satisfactory results, with economy in
cost, time, and labor.
The improvements will be principally applied in dealing with cyanide solutions
obtained from ores and the like; the application of them is not however limited to
such solutions.
In carrying out the invention according to one modification, the precious inetal
is obtained or separated from solution by precipitating it by means of an electric
current applied in a vat or box providel with special plates of a kind hereinafter
described. 'The plates to be used as anodes are of iron or steel and coated with
graphite or other suitable form of carbon. Plates of the same kind may be used
as cathodes; or the cathode plates may consist of iron or steel plates conted with
lead. Or iron or steel plates coated with lead oxide or other suitable oxide may
be employed for either anodes or cathodes, or for both.
The object of coating the anodes and cathodes in the manner above described is
that it is desired as far as possible to prevent the formation of ferro-cyanides, or
their insoluble salts, or insoluble salts derived therefrom, at the anode, and to
prevent the undue adhesion of the precipitated gold to the iron of the cathode, so
that all or nearly all of the precipitated gold may be easily removed.
The construction of the vat or box and the forms of the plates may be varied.
In a modification which may be described by way of example, the vat or box, made
of wood, is of an elongated form and of an approximately square section internally;
and the plates are placed transversely and are shaped to fit the bottom and sides
closely, being supported in grooves or in any other suitable manner. The plates
are made with parts extending above the parts to be immersed, the extensions
having holes formed in them to serve as handles and also to receive conducting
bars. Each plate is formed with a notch or cut-away part at a bottom corner or
at an upper corner; and a series of plates is arranged with lower notches at one
side of the vat alternating with upper notches at the other side. The lower and
upper notches are thus diagonally apart; and the solution admitted at one end of
the vat flows in a general diagonal direction between each plate and the next on
its way to the other end of the vat. The plates, which may be of a thickness of
about inch, are by preference, placed near each other. They may be inch,
apart, or even less provided the electric current cannot get across from plate to
plate (in consequence of contact of irregularities of surface, or of conducting
substances between the plates) without passing through the solution. The plates
may be kept at the proper distance apart by means of non-conducting buttons or
distance pieces attached to the plates. A convenient size of vat is one to contain
40 plates; and a convenient size of plate is one the immersed part of which
measures 12 inches by 12 inches. The coating of the plates with graphite may be
effected by mixing the graphite in a powdered condition with an extremely small
quantity of a varnish or resin diluted with a volatile solvent, and brushing the
mixture on the plates; or the graphite may be mixed with any other suitable
medium.
The electric current may be supplied or distributed to the plates according to
various arrangements, the arrangement chosen in each case depending on the kind
of current employed and other circumstances. Thus the plates may be made

page_text: alternately anodes and cathodes; or the plates at the ends of a series may be
connected respectively to the positive and negative poles of the electric source; or
with alternating anode and cathode plates in one vat or series, the cathode plates
may be severally connected to anode plates of a second vat or series, the cathode
plates of which are connected to a negative conductor. Any other suitable known
arrangement of the plates and current connections may be adopted. Electric
currents of various strengths and kinds may be employed; it may however be
stated by way of example and as a guide, that with a vat and set of plates such as
is hereinbefore described a current cf 5 amperes and 2 volts, has been found to act
satisfactorily with a solution containing one part of cyanide of potassium
per thousand parts of water, and to deposit therefrom a large percentage of what
recious metal it may contain.
The precious metal is deposited on the cathode plates and may be removed by
brushing or other means when the accumulation of it on the plates is considered to
be sufficient. If the electric working is interrupted, as at night for example, care
must be taken to prevent reversal of current, by withdrawing the solution, or by
any of the means for the purpose known to electricians.
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 obtaining precious metals from solutions by precipitating them
by means of an electric current applied in connection with iron or steel plates
coated with graphite or other suitable form of carbon or with lead oxide or other
suitable oxide, the apparatus being arranged and operating substantially as herein-
before described.
2. In the process referred to in the first claim, employing iron or steel plates
coated with lead, substantially as hereinbefore described.
3. In apparatus for separating precious metals from solutions by means of an
electric current, employing coated iron or steel plates placed inch, or less, apart,
and arranged substantially as herein before described.
Dated this 3rd day of July 1896.
ALLISON BROS.,
Agents for the Applicant.