Improvements in the Treatment of Gold Ores.
Year: 1893

page_text: Date of Application, 28th Dec., 1893
Complete Specification Left. 21st Sept., 1894-Accepted, 8th Dec., 1894
Improvements in the Treatment of Gold Ores.
I, HENRY LIVINGSTONE SULMAN of 60 Gracechurch Street, in the County of
Middlesex, Analytical Chemist, do hereby declare the nature of this invention to
be as follows:-
My process relates to improvements in the treatment of ores containing gold,
whereby the loss of the finely divided metal technically known as "Hoat gold " is
greatly or entirely prevented.
The loss which occurs from this source is mainly due, to the great difficulty
which exists in getting minute and finely divided particles and flakes of gold to
penetrate the surface of the water used in milling gold ores during the passage of
the crushed wet ore over mercury, or mercury amalgamated surfaces.
This float gold in many cases also partially escapes further processes designed to
retain it and such residual portions of gold as are not caught by the amalgamation
plant.
I have found by numerous experiments that the addition of certain substances
to the water, either before or after the mixing of the latter with the ore during
crushing, that the float gold may be made to enter the water and to subside
through it, in such a manner and with such readiness that the particles of the
metal shall be brought into contact with mercury during the passage of the crushed
and wetted ore over mercury amalgamated surfaces, whereby the said particles of
gold are arrested and retained by the mercury. Among the substances which I
have found to produce this effect to some extent, are the caustic alkalis and their
carbonates; but the substance I prefer to use and which possesses this property to
a much greater extent is soap.
The soap used may be made from any of the ordinary fats or fatty acids, resins,
or resin acids commercially known and used for such purposes, and may contain
either potash or soda as their base.
If desirable other substances may be added to the soap, but such must not
contain lime, or any other material capable of destroying or hindering the lathering
power of the soap.
The soap may be added to the milling water before crushing or at any period
subsequent to that operation, as may be desired; and this addition may be of the
solid substance, or more conveniently by means of a solution.
I have found that the employment of soap in the ways I have described, renders
the treatment of aluminous and talcose gold ores and of such other gold bearing
ores which are not readily wetted by water, much more easy and complete.
I have also found the presence of soap to be very beneficial during the
amalgamation of many varieties of sulphuretted ores, in keeping the surface of
the mercury clean and promoting the absorption of the gold.
A comparatively small quantity of soap is required relatively to the ore and
milling water employed and its action in rendering the float gold amenable to
retention by mercury is sufficiently powerful for practical purposes in the cold,
though hot water may be employed with the ore and soap if thought desirable.
The amount of soap necessary, will vary with the nature and hardness of the
milling water, and considerable economy in soap is to be effected by a preliminary
softening of the water supply, which may be done by any suitable method. The
quantity of soup required also varies with the nature of the ore, which latter may
be used raw, or may be roasted partially or completely, as found desirable. It is
of course necessary that the ore should not decompose the dilute soap solution
D

page_text: in which it is suspended during its passage through the usual milling and
amalgamating machinery processes or that it should only do so with great
slowness.
The actual amount of soap to be used with a given ore and milling water must
be determined at each mill by direct experiment, but the quantity need not be
large enough to produce any considerable amount of frothing. In certain cases I
have found the addition of Icwt. of a good soda soap to every 10,000 gallons of
water, employed in milling, to give a good result; but these quantities may be
varied considerably according to requirements.
If found necessary further proportions of soap, or of soap solution may be added
at later periods during the passage of the ore and water through and over the
various amalgamating machines and processes.
After this has been effected, and the non-gold-bearing portions of the ore have
been separated from the soapy liquor, by deposition filtration etc., the said liquors
may be treated with any suitable precipitant for the purpose of recovering the
fatty and resin acids, of the saponaceous material used as insoluble soap or soaps.
Lime water or a soluble salt of lime effects this precipitation by forming
insoluble lime soaps with the above acids; these form curds in the liquor, and
may be retained by straining filtration deposition or by any other suitable means.
This recovered curd will retain any portions of float gold which may have
escaped, and these and the fatty acids of the insoluble soaps may both be recovered
by any suitable means-as for example-by treatment with a dilute mineral acid,
such as sulphuric; this liberates the fatty acids which float on the surface and
may be collected and utilised for making fresh soap whilst the gold remains with
the acid liquor and calcium sulphate precipitate below and may be recovered by
any desirable means.
Dated this 28th day of December 1893.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Gold Ores.
I, HENKY LIVINGSTONE SULMAN of 60 Gracechurch Street, in the County of
Middlesex, Analytical 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 :-
This invention relates to the recovery of precious metals, especially gold, from
ores, the invention being particularly directed to the recovery of "float" and inely
divided gold. The ores may be treated by the ordinary processes such as crushing
and amalgamating bydraulic and similar processes which need not be further
described here. It is well known that in these processes a very large quantity
of the float and finely divided gold escapes in the effluent water, some of it being
carried upon the surface and some in suspension in the water. Now I have found
that by destroying (or, more accurately, diminishing) the "surface tension" of th
water the gold which was previously supported upon the surface of the
water, will be precipitated, and can be easily collected. The destruction of
the surface tension may be effected by the addition to the water of substances
such as the caustic alkalies and their carbonates, soda cresylate, alkaline dextrins,
and albumens, saponin, and quilloa-bark, but the cheapest and most satisfactory
substance appears to be soap. This may be made from any of the ordinary fats
or fatty acids, resins or resin acids commercially known and used for such purposes
and may contain either potash soda or ammonia as its base. I prefer to apply the
soap in a fluid condition through suitable pipes or jets as found most convenient

page_text: and its effect is to promptly destroy the surface tension of the water and pre-
cipitate the gold floating thereon, which will then readily adhere to the
amalgamating surfaces.
The soap may be added to the milling water before crushing or at any period.
subsequent to that operation as may be desired, and it may be in the form of a
solid substance but more conveniently as a solution.
The finely divided gold in suspension in the milling water I recover by mixing
with the water a substance which can be made to form a coagulum and to
precipitate so as to draw down with it the finely divided gold. This affords
another reason for preferring soap or a saponaceous substance for the purpose of
destroying the surface tension. The soap is soluble in the milling water and mixes
with the whole of it, so that by subsequently precipitating or coagulating the
soap I can secure in the manner above referred to the finer particles of gold which
are in suspension in the water. It is however not necessary that soap should be
selected for this purpose.
Various substances may be employed to effect this
precipitation such as lime, alum, magnesia, and many other metallic salts. Acids:
also inay be used for this purpose such as dilute sulphuric or muriatic acid, but as
many of these substances are difficult to obtain at the mines and expensive, [
prefer to employ soap and to coagulate it with lime water or a soluble salt of lime.
The saponaceous material is thus recovered as an insoluble soap or soaps and the
fine particles of gold are found entangled in the curd thus formed.
As the water obtained in the mines and used in the treatment of the ores is
usually hard and would therefore require a large quantity of the saponaceous
substance to give the desired results I prefer to soften the water before using it as
less soap
is required and a larger proportion of gold is recovered. Adding a larger
proportion of soap to hard water is not nearly so effective as softening the water
first.
Any of the well known processes may be employed for this purpose say for
example by treatment with lime, soda ash, aluminate of soda etc.
I have found in several cases that from 1 to 2 cwt. of soap when dissolved in
water and run into the stamp boxes of a battery is sufficient to prevent the
formation of float material during the treatment of such a quantity of ore as can
be treated by 20,000 gallons of milling water properly softened as before described;
and it is also sufficient to effect the precipitation of suspended matters, after
amalgamation, arising from the same amount of ore, in the manner to be now
specified. I do not limit myself to these proportions but give them as a guide to
quantities in average cases.
The subsequent precipitation may be effected when the soapy water is run into.
tanks, the water after the precipitation being strained through coarse strainers and
the coagulum dug out and thrown aside to drain, after which the gold may be
recovered from it in any desired mauner, conveniently by burning and subsequent
treatment by one of the well known processes. Acids may be used for this
purpose, but owing to the difficulty of obtaining them at mines, burning is
preferable.
Where it is not necessary to destroy the surface tension, another kind of
coagulating substance may be employed, such for example as alumn sulphate of
iron, silicate of soda, aluminate of soda and other substances which when dissolved
in water produce a gelatinous or flocculent precipitate upon the addition of a
decomposing substance such as lime. This precipitate or coagulum will entangle
or contain the finely divided gold and may be recovered by straining as before.
Having now particularly described and ascertained the nature of the said inveu-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The process of recovering Hoat gold by the addition to the milling water of
substances which diminish the surface tension of the water so as to cause the float
gold to leave the surface and deposit.

page_text: 2. The process of recovering finely divided gold in suspension in the milling
water by dissolving therein substances capable of being precipitated in the form of
a curd or coagulum and precipitating the same so as to cause them to bring down
with them the gold in suspension.
3. The use of soaps or saponaceous matter for the purpose of recovering float
gold as above described.
4. The use of soaps or saponaceous matter for the purpose of recovering finely
divided gold in suspension as above described.
5. In a process for recovering float gold by means of soaps or saponaceous,
matter as above described softening the water and in the milling process previously
to adding the soap or saponaceous matter thereto.
6. In a process for recovering finely divided gold in suspension by means of
soaps or saponaceous matter as above described the employment of lime water or
salts of lime for the purpose of subsequently precipitating the same.
7. The herein described process for recovering gold in milling operations
consisting of the following steps:-
(1) (If necessary) softening the water to be used in milling.
(2) Adding soap or sapouaceous inatter to precipitate the float gold.
(3) Precipitating the soap or saponaceous matter by the addition of lime water
or salts of lime to bring down the finely divided gold in suspension.
Dated this 20th day of September 1894.
HENRY LIVINGSTONE SULMAN.
W. P. Thompson & Boult,
Agents for the Applicant.