Improvements in and connected with Solvents for Metals and the Treatment of Gold and other Ores for the Extraction of the Contained Metal.
Year: 1899

page_text: Date of Application, 1st May, 1899
Complete Specification Left, 30th Jan., 1900-Accepted, 24th Mar., 1900
PROVISIONAL SPECIFICATION.
Improvements in and connected with Solvents for Metals and the
Treatment of Gold and other Ores for the Extraction of the
Contained Metal.
I, SIDNEY TRIVICK, of Durham House, Clapham Common, in the County of
Surrey, Metallurgist, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in and connected with solvents for
metals and the treatment of gold and other ores for the extraction of the con-
tained metal therefrom in a cheap, efficient and simple manner, by a new and
improved method of chlorination without the use of liquid acids.
The process consists in dissolving a suitable per-chioride and hypochlorite or
other salt in water alone or carrying, another or other salts, in solution such as
chloride of sodium or the like. 1 prefer to use per-chloride of iron and hypo-
chlorite of lime (bleaching powder) and with the solution treating gold and other
ores, tailings, concentrates, slimes or other material amenable to the process
when in a powdered or pulverised condition, with or without previous roasting
or preparation, the metals being brought into such a condition that their pre-
cipitation and separation can easily be effected.
To carry out my invention 1 place the ground or pulverised ore, tailings, con-
centrates, slimes or other material to be treated into any convenient vessel, vat,
barrel or cylinder which may be kept in motion or not, or any other suitable
apparatus can be used. I then, treat the material with a leaching solution com-
posed of perchloride of iron and hypochlorite of lime or other salt dissolved in
water, or separate solutions of perclitoride of iron and hypochlorite of lime may
be used, and added one after the other to the material under treatment, of
course, the perchloride of iron and hypochlorite of lime or other salt may be
brought together in various ways, for instance, the per-chloride of iron may
be added in a solid form, well mixed with the material under treatment, and
a solution of hypochlorite of lime may then be used as lixiviating liquor, or
the reverse may be done. In any case, allow the leaching solution to be in
contact with the material under treatment until the extraction or lixiviation is
complete, the duration of which depends upon the class of material under
treatment.
When the operation is complete the liquid after filtration may be brought
away by any suitable means to the precipitation tank, vat, or barrel and treated
by any of the well-known methods suited to the metals present for their
precipitation and separation.
In case of the material under treatment containing silver, chloride of sodium
may be added to the leaching solution, or a brine solution may be used after
the leaching solution has been removed from the material under treatment and
in this way more effectually recovering the silver chloride formed in the ore by
the chloridising leaching solution.
The strength of the leaching solution or solutions and the methods of appli-

page_text: cation depends on the nature and class of material to be acted upon; a solution
of per-chloride of iron and a solution of hypochlorite of lime when brought
together at ordinary temperature produces a most powerful chloridising com-
pound, nascent chlorine being at first quickly, then gradually and continuously
evolved.
It may further be noted that the hydrated ferric oxide formed on mixing
the two solutions, re-dissolves and probably forms ferric oxychloride.
Such a solution dissolves gold and other metals with great rapidity. Obviously
the solution may be brought together in different strengths and proportions to
suit specific conditions.
Whether a preliminary roasting, washing or other treatment would be advan
tageous for a larger, or practicably complete extraction of the valuable metals.
would depend on the nature and composition of the ore or material to be
treated.
SIDNEY TRIVICK..
Improvements in and connected with Solvents for Metals and the
Treatment of Gold and other Ores for the Extraction of the
Contained Motal.
1, SIDNEY TRIVICK, of Durham House, Clapham Common, in the County of
Surrey, in England, Metallurgist, do hereby declare the nature of this invention
and in what manner the same is to be performed, to he particularly described
and ascertained in, and by, the following statement:-
This invention has for its objects improvements in, and connected with,
solvents for metals and the treatment of gold and other ores for the extraction
of the contained metals, in a cheap, efficient, simple and rapid manner.
In the usual methods of chlorination for the extraction of metals by the use
of chloride of lime and an acid, the process is exceedingly crude, wasteful, and
expensive, for the commercial chloride of lime contains not only the chlorine
producing compound calcium hypochlorite, hat also the worse than useless acid
absorbing compounds, in quantities varying in good samples from 25% to 30%.
This, naturally, canses a great waste of acid, and the poorer the chloride of
lime in available chlorine the greater the waste of acid. Even under the best,
and cheapest conditions the process is very crude, wasteful, and expensive, one
hundredweight of good commercial chloride of lime containing one third its
weight of available chlorine, requires about one hundred and forty pounds of
liquid sulphuric acid to evolve the available chlorine, and this would treat,
under favourable conditions only four to five tons of ore; there is also the
danger, difliculty and expense of transporting liquid acids. I am aware several
processes have been proposed, substituting the liquid acid by a neutral or acid
salt of some of the metals, but all more or less labour under similar disadvantages.
In carrying out my invention. I use a solution of calcium hypochlorite, O'L
solution of the hypochlorite of one of the alkalies, with a solution of a suitable
salt, such for instances as ferric chloride, ferric sulphate, manganese sulphate
(especially the crude sulphate containing ferric sulphate), manganese chloride.
(especially the crude chloride containing ferric chloride), aluminium chloride
aluminium sulphate, many of the alums, oxalic acid, and in fact the number
of suitable salts is so large that it is impossible to name them all, but, it may
be taken that any salt which on the addition of either calcium hypochlorite
or the hypochlorite of any of the alkalies, evolves either chlorine, or any of

page_text: the oxy-acids of chlorine, is suitable, and under such conditions many dissolve
gold readily.
Such salts may be classified as follows:
I. Salts which on the addition of one of the above named hypochlorites form
oxychloride and evolve chlorine, at first quickly, and then slowly, such as ferric
chloride.
II. Salts which on the addition of one of the above named hypochlorites evolve
chlorine quickly, such as hydric oxalate (oxalic acid).
III. Salts which on the addition of one of the above named hypochlorites
evolve any of the oxyacids of chlorine, such as aluminium sulphate.
It is important to observe, that, in the case of salts capable of forming soluble
oxychlorides, when acted on by the hypochlorites. the latter should be added
to the former only so long as the precipitate formed redissolves, as it is under
these conditions that the chlorine is gradually evolved so as to act most effec-
tively on the material under treatment.
Solutions of the above mentioned hypochlorites, and salts, are made either in
water alone or in water carrying some salt, as for instance, sodium chloride,
for dissolving any silver chloride that may occur in the material under treatment.
I avoid the use of sulphates or acid sulphates of potassium. sodium, and
ammonium, for they are apt to form salts with compounds in the material under
treatment which are detremental to the process.
It is obvious, that, the selection of the reagent to be used with the calcium
hypochlorite, or hypochlorite of the alkali metals, to obtain the maximum result,
at a minimum cost, will, to a great extent, depend, on the material to be treated,
and on the geographical position of the works, and the distance from a chemical
manufacturing centre, or other source of supply, but preference should be given
in most cases to those salts which on the addition of one of the hypochlorites,
causes the chlorine to be gradually evolved.
Generally, I prefer to use a solution of ferric chloride in water, and a solution
of calcium hypochlorite in water.
The solutions may be prepared as follows:-
It
Three hundred and twenty-four pounds of commercial ferric chloride
(Fetl.610) is dissolved in one ton, or thirty six cubic feet of water; this may
be considered as equivalent to a 10% stock solution of ferrie chloride.
should be noted that the chlorine in the excess of terrie chloride, in this solution,
necessary to redissolve the hydrated ferric oxide formed on the addition of the
hypochlorite for the purpose of forming the ferric oxychloride is made avail-
able, thus considerably increasing the chlorodirising power of the lixiviating
solution.
Three hundred and thirty-five pounds of chloride of lime containing say 35%
of available chlorine, is well mixed with rather more than a ton of water, (say
37 cubic feet), and allowed to settle, the clear liquor being separated from the
insoluble residue, may be considered as a 9% to 10% or saturated stock solution
of calcium hypochlorite.
These stock solutions may be diluted with water s0 as to form solutions
varying in strength from 2% upwards, as occasion may require; the strength
of the solutions used depending on the nature and composition of the material
to be treated.
For treatment of gold ores for the extraction of the metals, the strength of
the lixiviating solution is, on an average, half to three quarter per cent., it being
borne in mind that the chlorine being in the nascent state it is at its fullest
strength, thus enabling weak solutions to be employed with advantage, indeed,
in some cases the chlorination may be carried on in open vats, so that almost
any existing plant may be used, as the chlorine being under control only suffi-
cient of the solution need be employed to bring the metals into solution. Experi-
ments on gold leaf show that these dilute solutions dissolve gold rapidly, in
fact, in about one third the time required by cyanide of potassium solutions.

page_text: It should be observed, that, the solutions should not be mixed, excepting for
immediate use, as when mixed decomposition commences at once.
With a lixiviating solution composed of a dilute solution of calcium hypo-
chlorite, or other suitable hypochlorite, and ferric chloride, or other suitable
salt, treat materials amenable to the process when in a powdered or pulverised
condition with, or without, previous roasting, or preparation, of course, in the
treatment of gold or other ores, unless the gold or other metals present in the
ore are accessible to the action of the chlorine they must be made so by previous
preparation, therefore, with ores and concentrates containing a considerable
amount of heavy sulphides carrying the gold, a preliminary roasting would, no
doubt, be necessary for a practically complete extraction of the gold, some of
the other objectionable substances which should be eliminated from ores con-
taining them for their successful treatment are, ferrous salts, and carbonates,
if present in considerable quantities, metallic iron, arsenical ores, antimonial
ores. zine blende, and tale. this may be done by roasting with, or without.
chloride of sodium as may be necessary, or by any other means, but whether
it would be most profitable to treat an ore raw, or after roasting, or preparation
by any other menus, should be determined in each case, by actual experiment.
The general treatment of gold or other ores for the extraction of the metals
is as follows:-
-
The finely pulverized ore. tailings, concentrates, slimes, or other materials
amenable to the process, is placed into any convenient vessel, vat, barrel, or
cylinder, which preferably, may be kept in motion, I then add to the material
under treatment the prepared solution of a suitable salt with a suitable hypo-
chlorite, either together, or separately which, preferably, should be in sufficient
quantity to thoroughly saturate the charge, and each solution of such strength
that equal volumes may be sufficient for the complete reaction required, and
allow the solution to remain in contact with the material until the metals
desired are brought into solution, the time necessary for the completion of this
operation depends upon the class of material treated.
When the solution of the desired metals is effected, the liquor is separated
by filtration, or by any other suitable method, and is treated for the extraction
of the metals it contains by any of the well known means suitable to the
metals present for their precipitation and separation.
If silver be present sodium chloride should be added, unless there be some
other solvent for silver chloride, such as calcium chloride, present in the solution
in quantities sufficiently large to dissolve the silver chloride. If desirable, or
preferred, a brine leaching solution may be used after the material has been
freed from the gold dissolving solution, and from the brine liquor the silver
may be recovered by any of the well known methods. Should the material
under treatment contain copper, the copper may be obtained from the lixiviating
solution by precipitation with metallic iron.
It is olivious, that, instead of the lixiviating solutions above mentioned,
chloride of lime, and any other of the suitable salts may be brought together
in various ways, taking care they are added in sufficient quantities, and proper
proportions, for complete reaction, as for instance, chloride of lime may be
added solid to the ore, the two well mixed, and the solution of the other salt added,
or the reverse may be done, or both may be added solid to the ore, and water
used as a
lixiviating liquor, which should in every case be. in suflicient quantity
to saturate the charge to a thick pulp, so as to bring every particle of the
material under treatment in contact with the solvent solution, which could not
be the case, if only 5% or 10% of solution were added.
I am aware that certain metallic salts have already been proposed, for use
in a somewhat similar manner, but as before shown, when chloride of lime is
used in the solid state. it is, at best. but a crude, wasteful, and expensive
method, and in some cases inadequate for efficient and rapid working, as a large
quantity of calcium chloride is often brought into solution, which greatly inter-
feres with the subsequent recovery of gold from the solution.

page_text: As many of the telluride of gold ores yield readily to this process, with no
preparation beyond being finely pulverised, I will, as an example, of the practical
application of this invention describe the treatment of twenty-five tons of such
an ore, for the extraction of gold and tellurium, by the use of a solution of
ferric chloride. and calcium hypochlorite.
A portion of the ore is tested in the laboratory to ascertain the strength of
the solutions to be used, which it may be assumed will be one per cent. ferric
chloride solution, and one per cent. calcium hypochlorite solution, the combined
solutions containing about 28 litres of available chlorine to the cubic foot.
The finely pulverised ore is placed in a revolving barrel, or cylinder, and
equal volumes of one per cent. ferric chloride solution, and one per cent. calcium
hypochlorite solution are run in separately, but simultaneously, until the ore
has become thoroughly saturated: the quantity of each solution usually required
for a charge of twenty-five tons of such an ore is between four and five tons.
The cylinder, or barrel, is then set revolving for two or three hours, when,
usually, a test shows the solution to be clear and colourless, its contents are
then thrown into a large filter tank. the cylinder or barrel, being carefully
washed out with water into the filter tank, and the whole is then exhausted by
filtration. the filtrate being passed into a precipitating tank. There being still
a quantity of liquor containing gold in solution mechanically retained by the
exhausted ore, this must be displaced by an equivalent quantity of water, and
the filtrate run into the precipitating tank.
Should there still be traces of gold in solution in the ore, it must be washed
out, the washings being retained in a separate tank.
If the solution in the precipitating tank contains much calcium, or lead.
sulphuric acid, or the like must be added, and it must be allowed to stand till
the precipitate has settled, when the clear liquor is separated, in any case, the
solution should be slightly acid. as, if neutral calcium chloride is present it
will cause a bulky precipitate on the addition of ferrous sulphate for the precipi-
tation of the gold.
Sufficient ferrous sulphate to precipitate all the gold in solution is now added,
but not in large excess. the whole being allowed to stand till the gold has
settled down, which will take place in a few hours, the clear solution is now
passed through a bed of charcoal to remove any traces of gold, which may be
in the liquor, and then run into the tellurium precipitating tank.
The pre-
cipitated gold may now be collected, washed and fused, and the gold recovered
periodically from the charcoal, by burning to an ash, and fusing the ash with
Hux.
The clear solution in the tellurium precipitating tank may be treated with
metallic zinc, which will precipitate the tellurium in a spongy state, the spongy
precipitate after rapid washing with water acidulated with hydrochloric acil.
may be fused as crude tellurium.
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
1 claim is
1. Improved solvent for metals, and for the treatment of gold and other ores
for the extraction of the contained metals, consisting of a solution of ferric
oxychloride, formed by the addition of a solution of calcium hypochlorite obtained
by adding water to chloride of lime, and then mixing the clear solution thus
obtained with aqueous solution of ferric chloride, so long as the hydrated ferric
oxide precipitate redissolves. substantially as described.
2. Improved solvents for metals, and for the treatment of gold and other
ores for the extraction of the contained metals, consisting of an aqueous solution
of one of the salts as classified herein, (with the exception of sulphates and acid
sulphates of alkali metals), as for instances, ferric sulphate, manganese sulphate,
manganese chloride, aluminium chloride, aluminium sulphate, oxalic acid and

page_text: the like, which on the addition of one of the hypochlorites either calcium or
alkali metals, evolves chlorine, or oxyacids of chlorine, substantially as sel
forth.
3. Improved solvents for metals, and for the treatment of gold and other ores
for the extraction of the contained metals by the addition of one of the salts,
as herein classified, in the solid state, well mixed with the ore or other material,
and by adding thereto a solution of calcium hypochlorite, or of one of the hypo-
chlorites of the alkali metals, dissolved in water alone and used as a lixiviating
solution or chloride of lime may be mixed in the solid state with the ore or
material, and a solution of one of the salts used as a lixiviating solution: or both
the salt and chloride of lime may be mixed in the solid state with the ore or
other material, and water alone, or mixed with sodium chloride, used as a
lixiviating solution, substantially and for the purpose as set forth.
1. The process, as fully described in the above specification, for the purposes
specified.
SIDNEY TRIVICK.
Applicant.