Improvements in the Separation of Gold and Silver from Ores or Materials containing them.
Year: 1890

page_text: Date of Application, 28th Feb., 1890
Complete Specification Left, 15th Dec., 1890-Accepted, 7th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Separation of Gold and Silver from Ores or
Materials containing them.
I, WILLIAM DUNSMORE BOнм of 51 The Avenue, Acton in the County of
Middlesex, Metallurgical Chemist and Engineer, do hereby declare the nature of
this invention to be as follows:-
'My invention has for its object to provide means whereby gold or silver or both
are obtained in a more ready perfect and efficient manner than hitherto and my said
invention has reference more particularly to the, leaching process known as the
"Hungarian process."
When
The
According to the said Hungarian process the ground ores after being roasted
with chloride of sodium and with added copper pyrites or sulphide of copper (if
copper be not present in the ore) are treated with a sclution of chloride of sodium
and chloride of copper which is caused to percolate through the ore. The liquid is
conducted into vessels in which the gold and silver are precipitated by means of a
solution of oxide of calcium and sulphur with or without chloride of sodium.
precipitation has taken place the supernatant liquor is run off for re-use.
According to my invention I add to the aforesaid leaching solution hydrochloric
acid or bromine, or both, before the solution is passed through the ore.
solution is by preference used in a heated condition which heating may be effected
by passing the solution: through chambers surrounded by a hot water jacket heated
by the roasting furnace or by other suitable means. The solution is then passed
through the divided ore preferably by means of a force pump and in an upward
direction in a vessel chaving a filter at top. The liquid is then passed into a
precipitating vessel in which it is agitated with a precipitant which I prefer to be
sulphide of sodium. The liquid is then by preference forced up through a filter and
may be passed to the heating vessel for re-use. The precipitate may then be pressed
and treated for the obtainment of the metals in the usual or any suitable way. The
ore from the leaching vessel may be washed over a plate of zinc or alloy of zinc
with other suitable metal, by acidulated water so that hydrogen is evolved and
thence over an amalgamated copper plate.
Ditadushi ooth 1
1000
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London,. W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Separation of Gold and Silver from Ores or
Materials containing them.
I WILLIAM DUNSMORE BOHм of 51 The Avenue, Acton in the County of
Middlesex, Metallurgical Chemist and Engineer 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 has for its object to provide means whereby gold and silver can
simultaneously be obtained from ores or materials containing them in a more ready
perfect and efficient manner than hitherto and my said invention has reference to
leaching processes in which chloride of copper is present in the solution used in
leaching (whether the same is purposely added thereto or is present in the ore when
subjected to the leaching) such as that known as the Hungarian process.
• According to the said Hungarian process the ground ores or materials after being
roasted with chloride of sodium and with added copper pyrites or sulphate of copper
[ Q77

page_text: (if copper be not present in sufficient quantity in the ore or material) are treated
with a solution of chloride of sodium and chloride of copper in water which is caused
to percolate downwards through the 'ore or material the proportion of chloride of
sodium being usually sufficient to-make a solution of 1150 density reckoning water
at 1000 and the chloride of copper being added as a strong solution usually in about
the proportion of not more than one per cent. of the chloride of sodium solution.
The liquid is conducted into vessels in which the gold and silver are precipitated
by means of a solution of oxide of calcium and sulphur with or without chloride of
sodium. When precipitation has taken place the supernatant liquor is run off
for re-use.
According to my invention in carrying out the process I add to the aforesaid
leaching solution hydrochloric acid and bromine before the solution is passed
through the divided ore or material.
=
The solution is forced through the divided ore or material by means of a force
pump in an upward direction in the leaching vat having a filter at the top. The
pressure necessary to effect this is considerable and greater than atmospheric
pressure. The liquid from the leaching vat is then passed into a precipitating
vessel in which it is agitated with a precipitant which I prefer to be sulphide of
sodium in quantity sufficient to throw down the greater part of the gold and silver
from the solution copper being left in solution. The reactions in this precipitation
are expressed by the following equations:-8. Au Br, + 12 ON, +3 Cu S = 8
Au +3 Cu SO, +24 H Br and 2 Ag. Cl + Na, S
Ag, S+ 2 Na Cl. The
quantity of sulphide of sodium should therefore be in accordance with the amount
of precious metals in solution and the quantity necessary can be ascertained by
taking a sample of the solution with the precipitate in suspension, filtering and
testing the filtrate with ammonia for the presence of copper. If the test shews that
the copper of the leaching solution has been thrown down the quantity of precipitant
must be lessened until the test indicates that the solution retains its normal amount
of copper.
The liquid is then forced up by a force pump through a filter for the
purpose of collecting the precipitate and the solution which passes from the filter is
strengthened for re-use in the leaching vats by adding (in addition to the chlorides
of sodium and copper) bromine and also hydrochloric acid if required and is again
forced as described through the leaching vats being first (if the solution is to be
used in a heated condition which I prefer) passed through the heating vessel.
I find in most cases one part; of bromine (added gradually to the solution as it
circulates) to each two thousand parts of the ore or materiali under treatment
sufficient but in dealing with some ores or materials which are very rich in finely
divided gold it is advantageous to increase the quantity of bromine for instance to
as much as one part of, bromine to each one hundred parts of the ore or material
under treatment. The hydrochloric acid should be added in such quantity as to
make the solution just sufficiently. acid to react on test.paper. The heating of the
solution (if it is to be used in a heated condition for leaching) may be effected in
any suitable way for example by passing the solution through a chamber surrounded
by a hot water jacket or having in it a coil and the water supplied to this jacket or
coil may be heated by the roasting furnace or by other suitable means.. . The hydro-
chloric acid keeps the solution free from carbonate of copper and renders it more,
active. The addition of the bromine causes the following: reaction to take place
Au 3 Br
Au Br-3. The precipitate may be pressed and treated for the-
obtainment of the precious metals in the usual or any suitable way. The ore or
material from the leaching vessel may after leaching be washed with warm or cold,
water to remove the last traces of the solution and such wash water, and solution
removed by it may be run into an evaporator to be concentrated before being added
to the solution for re-use. The ore may then be washed out from the vat, over a
plate or surface of zinc or alloy of zinc. by acidulated water so that hydrogen is.
evolved and thence into contact. with mercury preferably in the form of.an
amalgamated copper plate or surface which retains any gold and silver, which may
remain in the ore in the vat and which would otherwise be lost.
=

page_text: I do not limit myself to any one precise form of apparatus for carrying out my
invention, but the apparatus described in the Specification of my application for
Letters Patent No. 3246 of even date herewith is well adapted for the purposes of
my present invention.
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. In the processes such as herein specified the use in the leaching solution of
bromine with or without hydrochloric acid substantially in the manner and for the
purpose herein before described.
2. In processes such as herein specified wherein bromine with or without hydro-
chloric acid is used as claimed in the first claim the conducting the processes in the
following manner :- -The leaching solution is pumped upwards as described through
the leaching vat and its filter and then through the precipitating vessel and its filter
and is then brought up to normal strength and again forced upwards through the
said vat vessel and filters as described.
3. The combination of processes such as herein specified wherein bromine with or
without hydrochloric acid is used as claimed in the first claim with the use of
sulphide of sodium as a precipitant for the solution after leaching substantially as
described.
Dated this 27th day of November 1890.
J. H. JOHNSON & Co.,
Agents.