A New or Improved Method of and Process for Treating Antimonial Ores containing Precious Metals.
Year: 1897

page_text: A New or Improved Method of and Process for Treating Antimonial
Ores containing Precious Metals.
I, NATHANIEL WALLABI EDWARDS, of 26, Jewin Crescent, in the City of London,
Merchant, do hereby declare the nature of this invention to be as follows:
My invention relates to a method of and process for treating antimonial ores
whether auriferous, argentiferous or antimonial only.
Hitherto antimonial ores have been treated by clectrolysis or by smelting, and
both methods are costly and inefficient. The presence of antimony in gold-
bearing ore has such neutralising and deleterious effects upon the mercury used
for amalgamation that amalgamation does not take place and the bulk of the
gold passes away and is lost in the tailings. According to my new or improved
method I first dissolve by the action of sulphide of calcium the antimony
(stibnite" or sulphide of antimony) and remove same from its matrix leaving
the gangue and its contained gold or precious metal free for further treatment. by
known and working methods. The ore can then be treated by any process while
both the antimony and the solvent are recovered. According to my new or
improved process I suitably comminute the dry ore and then treat it with a
solution of sulphide of calcium (or "yellow liquor") of proper strength and pre-
ferably in a cold state:
The treatment is continued with successive quantities of the solution until the
sulphide of antimony is dissolved out of the ore which is then washed with water
and the residue carrying the gold or metal and gangue is ready for pan amalga-
mation, cyaniding or other method of treatment. In carrying out my process in
order to economise the solution the ore is best worked in dissolving vats arranged
in series and provided with suitable mechanical agitators to accelerate the result.
Eventually, I thus obtain a concentrated solution of antimony in the sulphide of
calcium solution. Then to recover the sulphide of calcium the solution is sub-
jected in closed vats to the action of carbonic acid gas. This first precipitates
the lime as carbonate which is settled or filtered off; then the continued addition
of carbonic acid gas precipitates the sulphide of antimony in a merchantable
form.
Under the action of the carbonic acid gas upon the antimony solutions as
described, sulphuretted hydrogen is given off. This is in turn passed through
milk of lime forming a fresh quantity of sulphide of calcium solution which is
available for treating further quantities of crushed antimonial ore as above
indicated.
For the precipitation of the antimony it is convenient to employ vats adapted
to hold a quantity of solution equal to the capacity of the dissolving vats, and
also to provide a stock of sulphide of calcium solution of at least equal quantity.
By thus completely dissolving and removing the antimony from the ore the
great trouble and cost previously experienced in getting the gold or precious
metal therefrom is overcome, and more of it is got since none or practically none

page_text: is lost. No furnacing is needed in the operations, and the cost of my treatment
is much less than that of any method or process hitherto practised. By my inven-
tion low-grade gold-bearing ores such as have hitherto been neglected on account
of the expense and uncertainty of their successful treatment by existing methods,
can be profitably utilised.
A New or Improved Method of and Process for Treating Antimonial
Ores containing Precious Metals.
I, NATHANIEL WALLABI EDWARDS, of 26, Jewin Crescent, in the City of London,
Merchant, 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:-
-
My invention relates to a method of and process for treating antimonial ores
(in which the antimony exists as sulphides), whether auriferous, argentiferous or
antimonial only.
Hitherto antimonial ores have been treated by electrolysis or by smelting, and
both methods are costly and inefficient. The presence of antimony in gold-
bearing ore has such neutralising and deleterious effects upon the mercury used
for amalgamation that amalgamation does not take place and the bulk of the
gold passes away and is lost in the tailings..
According to my new or improved method I first dissolve by the action of
sulphide of calcium the antimony ("stibnite" or sulphide of antimony) and
remove same from its matrix leaving the gangue and its contained gold or precious
metal frce for further treatment by known and working methods. The ore can
then be treated by any process while both the antimony and the solvent are
recovered. According to my new or improved process I suitably comminute the
dry ore by any of the well known methods, and then treat it with a solution of
sulphide of calcium (or "yellow liquor."). I have found that good working
results attend the use of "yellow liquor" of a strength equal to 12° Twaddell
(Sp. Gr. 1060) and containing about 7% of mono-sulphide of calcium. I do not
however confine myself to the exact strength and may vary same so as to be
best suited to the particular ores under treatment. I also find that the best
results are obtained by using cold solutions.
The treatment is continued with successive quantities of the solution until the
sulphide of antimony is dissolved out of the ore which is then washed with water
to free the last of the liquor therefrom, and the residue carrying the gold or
precious metal and gangue is ready, according to its character, for treatment by
pan amalgamation, cyaniding or other method of treatment. In carrying out my
process in order to economise the solution it is convenient and effective to add
same and work the ores in dissolving vats of ordinary kinds (such for example
as are used for "black ash") arranged in series and provided with suitable and
preferably slowly revolving mechanical agitators to prevent settling and accelerate
the result. Thus the antimony is dissolved out of the ore, and eventually I obtain
a concentrated solution of antimony in the sulphide of calcium solution. Then to
recover the sulphide of calcium, the antimony sulphide solution according to my
invention is subjected in closed vats to the action of carbonic acid gas (obtained
preferably as lime kiln gas produced by burning limestones passed through same).

page_text: The result of thus passing carbonic acid gas through the solutions is first to pre-
cipitate the lime as calcium carbonate which is settled or filtered off; then the
continued addition and action of carbonic acid gas serves to precipitate the sulphide
of antimony contained in the solutions in a merchantable form.
Under the action of the carbonic acid gas upon the antimony solutions as
described, sulphuretted hydrogen is given off. This is in turn passed through
milk of lime forming a fresh quantity of sulphide of calcium solution which is
available for treating further quantities of crushed antimonial ore as above
indicated.
For the precipitation of the antimony it is convenient to employ vats adapted
to hold a quantity of solution equal to the capacity of the dissolving vats, and
also to provide a stock of sulphide of calcium solution of at least equal quantity.
By thus completely or as far as practicable dissolving and removing the anti-
mony from the ore the great trouble and cost previously experienced in getting
the gold or precious metal therefrom is overcome, and more of it is got since none
or practically none is lost. No furnacing is needed in the operations, and the
cost of my treatment is much less than that of any method or process hitherto
practised. By my invention low-grade antimonial gold-bearing ores such as
have hitherto been neglected on account of the expense and uncertainty of their
successful treatment by existing methods can be. profitably utilised.
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:-
1. The herein described method of treating antimonial and antimonial gold ores
which consists in dissolving by the action of sulphide of calcium the antimony con-
tained therein and removing same from the ores, leaving said ores and their contained
gold or precious metal free for further treatment by known working methods, and
subsequently treating the solution with carbonic acid gas, for the recovery of the
dissolved antimony sulphide.
2. The improved process. for the treatment of antimonial and anti-
monial gold bearing ores, consisting essentially in treating pulverized
antimonial or antimonial gold. ores, with a solution or solution of
sulphide of calcium, then treating the resulting solution or solutions
with carbonic acid gas to produce a precipitate of calcium carbonate,
then mechanically separating such precipitate and again treating the solution
with further carbonic acid gas to effect the precipitation of the antimony sulphide
therein contained, and removing the latter as a mechantable product and thus
leaving the ore residues to be treated in any approved or suitable manner, with
a view to the recovery of the gold therein contained whilst the evolved sulphu-
retted hydrogen is collected by passing the same through milk of lime forming
therewith a fresh supply of yellow liquor as and for the several purposes herein
set forth.