Improvements in or relating to Solvents for Metals and the Treatment of Gold and other Ores.
Year: 1897

page_text: Date of Application, 14th Dec., 1907
Complete Specification Left, 14th Oct., 1898-Accepted, 10th Dec., 1898
Dale ApplicatioIT,
Complete Specification Left, 14th Oct., 1898-Accepted, 10th Dec., 1898
PROVISIONAL SPECIFICATION.
Improvements in or relating to Solvents for Metals and the Treatment
of Gold and other Ores.
I, JAMES CHARLES RICHARDSON, of 19, Claremont Square, London, N., Electro-
chemical Engineer, do hereby declare the nature of this invention to be as
follows:-
-
According to this invention, for the purpose of dissolving gold and other metals
(including mercury), and treating gold and other ores, with the view of extracting
the more valuable metals therefrom, use is made of the well-known commercial
chemicals, perchloride of iron and permanganate of potash (which are obtainable
as innocuous solids, stable, and therefore practicable and cheap products, readily
transportable), soda, or their equivalents, dissolved in water, alone, or carrying
another salt in solution, as common salt, nitrate of soda, an acid salt, acid, or
the like.
Or I may employ a mixture of pernitrate, and (or) persulphate, and perchloride
of iron, or aluminie chloride, or a similar halogen acid-salt.
By bringing together concentrated solutions of ferric chloride and potassium per-
manganate, in water, even at normal temperatures, I am able to produce a most
powerful oxidising and chloridising compound, chlorine being given off, so that
few, if any, metals can resist its solvent action. They may of course be brought
together in any proportions suitable and convenient apparatus or way, order-as
the ferric salt added to the permanganate, which I find useful, or the reverse-
or form, as solid or liquid, or one solid and the other liquid. For treating gold
and other ores, I find adding the permanganate to the pulverised ore, and after-
wards the perchloride, useful.
The solution may be diluted as found desirable; applied under increased
pressure, of steam, air, carbon dioxide, or otherwise; or increased temperature,
by steam or otherwise; or the chlorine gas produced by the reactions used
separately.
The metals obtained in solution I precipitate or deposit electrolytically, by
other metals, or otherwise; and the solution, which, in virtue of its chemical (man-
ganese) constitution, is an excellent carrier of oxygen, may be revivified by air,
or carbon dioxide, acids, electrolytically, or otherwise; and any precipitate formed
during the reactions may be redissolved in soda or acid, if desired, or filtered or
settled out in well-known manner.
I also employ the permanganates or manganic salt (or, as applies to the fore-
going, manganate, chromate or bichromate, chromic, or their equivalents) alone,
or mixed with the halogen ferric or equivalent salt, or other per-salt, or with
caustic soda, or acid soda-salt, or in conjunction with air, or a blast of air, carbon
dioxide, or the like, under pressure if desired, for the purpose of sweetening the
ores, neutralising any free or loosely combined elements, or compounds, like, or
of, sulphur, arsenic, tellurium, and so rendering the ore free, stable and (the gold
particularly) clean, without roasting, preparatory to, and fit for, amalgamation
or evanidation treatment.

page_text: For the latter treatment I add permanganates or manganates of the alkalis,
or manganic or permanganic acid, to the solvènts or wash liquors, or to the ore
or slimes, which act as excellent neutralisers and oxygen carriers, and therefore
depolarisers of hydrogen, the element set free or molecularly displaced in the
reaction, and which polarises the gold; impeding or stopping its solution; and
bicarbonates of the alkalis, as bicarbonate of soda, or carbon dioxide under pressure,
which I may also use, as well as caustic soda, quicken the solvent in a most marked
degree, saving much time in the process, say, from the present four days required,
to one day; the bicarbonates, like carbon dioxide of the atmosphere or true carbonic
acid in water, carbonating the hydroxide, and so forming an alkali-carboxyl com-
pound which holds the (CN), OH(CN), or H(CN), more loosely than the hydroxyl
compound of the alkali, which renders it a quicker solvent, particularly if the
polarisation by hydrogen be prevented as before stated.
I would here observe, that the hydrocyanic acid does not liberate carbon dioxido
from the solutions of potassium or sodium carbonate, nor is any carbon dioxide
gas liberated from the solution when strong solutions of potassium cyanide and
bicarbonate are brought together 'at normal temperatures.
Dated this 14th day of December 1897.
Improvements in or relating to Solvents for Metals and the Treatment
of Gold and other Ores.
+
I, JAMES CHARLES RICHARDSON, of 19, Claremont Square, in the County of
London, N., Electro-Chemical Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed; to be particularly described
and ascertained in and by the following statement:-
The object of the present invention is the production of a solvent for gold and
the like and other metals, in the preparation of which solvent no liquid acids
shall be required, and which shall be cheap and effective for treating gold and
other ores by wet methods. In this I claim to have succeeded, as is hereinafter
shown.
The characteristic feature of my invention is the use of two solids, hereinafter
specified, which, when added to water, produce a solution' having remarkable
solvent powers.
The use of perchloride of iron' as a solvent for metals and for treating certain
classes of crushed metalliferous ores; including; gold ores, has been proposed from
time to time, and liquid acids, and mixtures thereof, have also been proposed.
It is, however, now known to metallurgical chemists and others, that, for the
purpose of, dissolving the precious metals, as gold, perchloride of iron solution,
prepared by dissolving the commercial solid salt in water, is not, per se, a practic-
able industrial gold solvent, even in the presence of air, which assists solution, and
the addition to it, or the direct use, of liquid acids of any description is greatly to
be objected to in the case of treating gold ores, and the like, on such grounds as
cost, difficulties and expense of transport, and chemical effects.
According to this invention, liquid acids are entirely dispensed with,, inasmuch
as solid perchloride of iron of commerce is rendered suitable and efficient for use
as a solvent for gold and like metals, and other metals, and for treating gold
and other ores in a crushed condition, with or without previous concentration
and (or) roasting, in the following manner, namely, by the addition of another
compound, an alkali permanganate, or alkaline earth permanganate, for example,

page_text: the well known commercial chemical, permanganate of potash, which, like the
perchloride of iron, is obtainable as a solid salt.
The remarkable chemical reactions between these two compounds when brought
together in solution in water at normal or elevated temperatures will be duly
appreciated by chemists and metallurgical technologists.
In carrying out my invention, to obtain a markedly powerful effect, I'prepare
and. bring together in any suitable containing vessel, tank, barrel, or equivalent
(as of wood, glass, slate, enamelled iron or Doulton 'tile-lined iron, brick, stone,
stone-ware, cement, or other suitable material) concentrated aqueous solutions
of these salts, for example, equal volumes of saturated solutions of ferric chloride
(perchloride of iron) and potassium permanganate (permanganate of potash), at
normal temperatures, and thereby I produce a most powerful oxidising and chlorid-
ising compound, chlorine being liberated chemically in the solution, part of which
is evolved as gas (which may be collected and used in that form, or retained in
solution under pressure in well-known manner), so that few, if any, metals, as
gold, copper and the like, can resist its solvent action.
The advantages following the liberation of the chlorine in a fresh, and active,
electrified condition, "nascent," so called, and concentrated form; in contact, say,
with crushed metalliferous ores, as gold.'ores, and 'the like, are well known and
appreciated.
Of course in some cases a preliminary treatment of the crushed virgin ore may.
be necessary, as will be understood, as,; for example, where certain sulphides,
arsenides, tellurides, and such like, exist.
After treatment with a smaller quantity of such a stronger solution, water
may be employed for leaching purposes in well known manner.
I apply my.
process with more or less success to all gold-bearing. ores.
A precipitate of oxides (manganese and iron) is produced if the compounds
are brought together in concentrated form, as first mentioned, or in chemical
excess, as would be expected, and this precipitate may be re-dissolved by alkali
or acid, if desired, or filtered or settled out in the usual way.
But obviously. the compounds may be brought together in proportions other
than saturated solutions, to suit specific requirements or conditions, and in different
order, that is to say, the ferric chloride solution may be added to the manganic
salt in solid form, as for example,, previously intimately mixed with pulverised
ore, or in the reverse order, and the solutions brought together in dilute form so
as to retain the chlorine (and, or, oxygen) in unstable chemical combination or
equilibrium or in solution, when the compound 'will be a clear solution having
great solvent power, dissolving, by. way of illustration, gold leaf greedily (and
therefore float-gold would be taken up).
A ten-per-cent. solution of perchloride and a five-per-cent., solution of perman-
ganate, when brought together in equal quantities by volume, produce such a
solution, in which gold is rapidly dissolved, and this, when broken down; diluted;
with water, produces a suitable compound for percolation or equivalent treatment
of crushed ores, or the like, carrying gold or other valuable metals; but I do not
confine myself to these proportions.
I would point out and emphasise this fact, namely, that the addition of the
merest pinch of permanganate to a comparatively large volume of the ferric salt'
solution, either dilute, say of specific gravity 1'010, or more concentrated, up to
saturation, raises it from an impracticable gold solvent to an efficient industrial
gold solvent, applicable to gold-ore and other metalliferous treatments in the wet
way, the formation of, or continuance of, ferrous salt in solution being avoided,
as may be anticipated; and that the permanganate can be added in smaller
quantities at a time up to the point of neutralisation to obtain a maximum yield
of chlorine at a not too rapid rate. But obviously the addition of the perman-
ganate need not exceed the yield of available chlorine actually required in the
solution at any stage of, or complete, operation.
.
If it be desired to extract the commoner metals, as copper and the like, first, the

page_text: addition of the permanganate may be left to the last or later applications of the
solvent, that is to say, the perchloride alone will dissolve certain of the commoner
metals, and the permanganate would be added to a fresh volume of solvent to obtain
the gold and the like in solution from the residue.
Such procedure, however, would be discretionary.
I sometimes employ extra pressures and temperatures on the solvent, with agita-
tion of the material or liquid; the reactions are hastened and rendered more com-
plete thereby, and the rate of solvent action generally accelerated.
For example, if the solid perchloride be melted by heating it in a stoneware
or stone closed chamber or still; and the permanganate added to it, or the two
introduced together, there will be very strong reaction and a copious evolution of
chlorine gas of very active quality.
Such increase of temperature, however, is not essential, whether produced by
direct heat or steam or by the reactions, except where the gases are so required to
be produced, or where exceptionally powerful oxidation or chloridisation is
required.
The essential and simple feature of my invention, it will be seen, is the addition
of a manganic salt, as permanganate of potash (and this I employ on account of
its efficiency, convenience, and cost, although in the course of my investigations
I find similar results are produced by the alkali metal and alkaline earth metal
peroxides, and some other like compounds, as chromic and alkali- ferric compounds,
hydrogen peroxide, but these are usually less adaptable, excepting, perhaps, sodium
or barium peroxide, certain alkali or alkaline earth chromic or ferric compounds,
and the like) to the ferric chloride, or equivalent haloid salt, which renders it
serviceable for the purposes indicated, and this even at normal temperatures;
and both salts being obtainable commercially and in a solid form, stable com-
pounds, and practically innocuous, no liquid acids, hydrochloric, sulphuric, or the
like, having to be used or carried-water alone being required-they are, from
these considerations, and from their remarkable chemical reactions one with the
other, in water, or when heated together, as already stated, peculiarly suited for
treating virgin or concentrated ores, tailings, slimes, or auriferous dirt, clays or
rock, in a crushed, divided condition, by wet methods, at a distance from chemical
manufacturing centres, and particularly gold ores carrying copper and other metals
or compounds which are not easily treated, or untreatable at a profit, by cyanide,
amalgamation and other methods, before or after concentration, oxidation by
furnace heat, and (or) weathering. Common salt or equivalent may of course
be added for the better obtaining silver chloride, and the like, in solution.
to an
I also employ solutions prepared by adding a smaller quantity of perchloride
excess of permanganate for the purpose of supplying oxygen to and
sweetening ores, before or after partial roasting or scorching, treating them in
a finely divided or crushed condition, as applies throughout this specification,
in the usual way, oxidising both organic and inorganic bodies, sweetening the ore,
and supplying oxygen to the solution, so that the gold in particular is freed and
cleaned, and the crushed ore or equivalent better fitted for subsequent treatment
by the present solvent process, by cyanide, or amalgamation extraction.
The solvent solution, prepared by adding the permanganate to the perchloride
in excess, dissolves mercury readily, so that this fact must be considered in
amalgamation methods.
The sweetening liquor, or residue thereof, may be washed out by water, if
desired, and the ore rendered alkaline or neutral, in the usual way, for cyanidation
or amalgamation. But this sweetening solution reacts with cyanide as to improve
its solvent action, when not in excess. At the same time, or at intervals, a blast
of air may also be employed, the manganese being an excellent carrier of oxygen,
which element, as known, facilitates, and in some processes is essential to, gold
solution, as by cyanide and the like, and necessary to the oxidation of unstable
sulphides.
I will now describe the treatment of, say, five tons of stable, crushed or finely

page_text: ground auriferous ore. I prepare a solution of perchloride of iron of 5 Twad.
[specific gravity 1025], sufficient to completely wet the ore (the solution may be
weaker than this). I then add the permanganate crystals in the proportion of
one lb. of permanganate to one ton of ore, afterwards agitating the mass as in
barrel treatment. [This permanganate may be added in solution.] The same
may be under pressure or heated, as before stated; but I prefer working at ordinary
temperatures. After the ore is so treated for an hour or two (and sometimes less,)
the gold will be obtained in solution, which solution is afterwards separated from
the quartz or other residue by settling, filtration, or equivalent, in the usual way,
any adhering solution carrying gold being leached or washed out with water, or
water carrying a trace of salt. If after this treatment any gold is found undis-
solved in the residue it may be treated as before. But I arrange as a rule that
one treatment only is necessary, increasing the chemicals if and when they are
required stronger. Such solutions, however, may be used over again, after the
manner of cyanidation, adding either more permanganate or perchloride as
required.
The process may also be carried out by percolation methods, passing the solution
[e.g., perchloride solution, specific gravity 1008 filtered rapidly through a layer
of permanganate crystals] through and through the ore, or series of batches of ore,
in well known manner, common to such methods, also employing the solution or
solutions over and over again.
For sweetening ores preparatory to or in conjunction with amalgamation or
cyanidation, I prepare the solution by adding to every 100 gallons of water 20 lbs.
of permanganate and 5 lbs. of solid perchloride, and add this solution to the
powdered ore in the usual way as and when required, with or without a blast of
air as an auxiliary oxidising agent.
But it will be understood and conceded by technologists, that, without departing
from the spirit of my invention, the quantities and proportions of the two particular
chemical compounds specified, and the physical conditions attending their applica-
tion, may be varied considerably to suit different ores, a preliminary trial or trials
being invariably necessary with any and every class of ore, to establish the best
conditions of treatment on a large scale, in different geographical positions, to
obtain a maximum yield at a minimum cost for chemicals and manipulation.
In brief, however, I may say that, in applying my solvent and sweetening compound
to auriferous and argentiferous and other ores, I adopt as far as possible the known
and well-tried mechanical methods of treating ores in the wet way.
Metals obtained in solution according to this invention may be precipitated
by other metals, as iron, zinc, and the like, by organic reagents, as carbon mon-
oxide, formic acid, formalin, aldehydes, and the like, or inorganic reagents, as
ferrous sulphate, sulphurous acid, and the like, or by electricity, which in some
cases, as where insoluble anodes are employed, would have the effect of revivifying
the solution to some extent for re-use. Such methods, however, are not the
subject of the present application, and need not be further referred to.
In conclusion, I would again observe that, unlike some other wet methods,
the only liquid required, in addition to the two solids named, for the successful
carrying out of my invention is water, liquid acids, as hydrochloric, nitric, sul-
phuric, or otherwise, being entirely dispensed with, as hereinbefore shown. [I am
aware that it has previously been proposed to use a permanganate in conjunction
with hydrochloric acid.]
.Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
(I.) The improved solvent for metals and for treating metalliferous ores by wet
methods, characterised by the employment of a haloid ferric salt, as ferric chloride,
or equivalent, in conjunction with a manganic salt, as potassium permanganate,
or equivalent, in the manner and substantially as set forth.

page_text: (II.) In preparing aqueous solutions of commercial solid perchloride of iron
for the purpose
of dissolving metals, including the precious metals,
as gold, thereby, and for treating virgin, concentrated, roasted or weathered
gold and other ores or earths in a crushed or finely divided condition,
with the view of obtaining gold and the more valuable commoner metals, as copper
and the like, therefrom, in solution, the addition to such solutions of alkali or
alkaline earth permanganates, as permanganate of potash, or equivalent, substan-
tially as set forth.
(III). The production of chlorine as gas or unstable compounds of chlorine
in solution, for the purpose of dissolving metals and treating gold and
-other metalliferous ores, or equivalents, by heating together or bringing together
in water the two compounds, perchloride of iron and permanganate of potashi,
or their equivalents, substantially as set forth.
(IV.) The employment of ferric chloride solution in conjunction with an alkali
permanganate solution, with or without a blast of air, for the purpose of supplying
oxygen to and sweetening gold and other ores, and as auxiliaries in amalgamation
and cyanidation, substantially as set forth.
(V.) The addition to ores of a manganate and (or) permanganate of any of
the alkali or alkaline earths in the manner and substantially as set forth.
(VI.) The herein described process for dissolving metals and treating auriferous
and other ores, consisting in the employment of the combination of the two solids,
perchloride of iron and an alkali or alkaline earth permanganate, such as perman-
ganate of potash, and water, without and in lieu of any liquid acids, substantially
as specified.
Dated this 14th day of October 1898