A NEW OR IMPROVED PROCESS FOR THE EXTRACTING OF SILVER, LEAD, COPPER AND ZINC FROM BLUESTONE AND OTHER MIXED ORES AND APPARATUS EMPLOYED THEREIN
Year: 1883

page_text: LETTERS PATENT to James Cross and George Isaac James Wells both of
Widnes in the County of Lancaster for an Invention of A NEW OR
IMPROVED PROCESS FOR THE EXTRACTING OF SILVER, LEAD, COPPER AND
ZINC FROM BLUESTONE AND OTHER MIXED ORES AND APPARATUS EMPLOYED
THEREIN
PROVISIONAL SPÉCIFICATION left by the said James Cross and George
Isaac James Wells at the Office of the Commissioners of Patents on the
10th May 1883.
JAMES CROSS and GEORGE ISAAC JAMES WELLS both of Widnes in the County
of Lancaster A NEW OR IMPROVED PROCESS FOR THE EXTRACTING OF SILVER,
LEAD, COPPER AND ZINC FROM BLUESTONE AND OTHER MIXED ORES AND
APPARATUS EMPLOYED THEREIN
This invention relates to the treatment of Ores containing various metals in
admixture.
The method hitherto adopted in wet processes for the extraction of metals from
complex Ores, is first to roast the Ore, with a view to eliminate the Sulphur
contained therein and then to extract the metals, such as Zinc and Copper, by
Hydrochloric Acid, Sulphuric Acid and other agents and afterwards the metals
such as Silver and Lead, by Brine or the Chlorides of the Alkaline earthy metals,
but these metals are only imperfectly separated by this method.
-
This invention consists in digesting the unroasted Ores (reduced to a fine state
of division) in hot Hydrochloric Acid, in vessels which we prefer to be constructed
of stone. The lead is then converted into Chloride which becomes soluble in
certain Menstrua. The liquor is then nearly neutralized with Lime or Carbonate
of Lime but leaving only a slight excess of Acid, then well boiled, settled, and
run off whilst hot, through a suitable Filter, into a tank where it is allowed
to cool.
The filter we propose to use is according to our Invention made of cakes of soft
peat laid close together on a sheet of asbestos cloth or other suitable woven

page_text: material or on perforated tiles or slabs supported on a wooden or other suitable
platform in a suitable tank, the filter being kept warm by hot air or steam and in
order to hasten the filtering process we prefer to apply a vacuum to the underside
of the filtering bed but if desired pressure can be applied to the top of the liquor.
This operation if necessary is repeated until all the Lead is extracted.
The tank Liquor after being cooled by artificial means or allowed to stand until
sufficiently cooled, deposits Crystals of Chloride of Lead, and is then run off into
another tank and the remaining Lead in solution is precipitated by the addition
of a solution of soluble Sulphide, the complex solution obtained from the drainage
of Alkali waste, being especially suitable for the purpose; or Sulphuretted
Hydrogen obtained directly from Alkali waste by the action of Hydrochloric
Acid thereon, or the Lead may be extracted in the metallic state by treatment
of the Liquor with Scrap Iron by the mode so extensively used for the extraction
of Copper.
The residue left in the stone vessels is taken out, washed, dried, and calcined
so as to drive off the Sulphur which goes off much more readily than from the Ore,
in its original state.
The calcined Ore is now treated with Hydrochloric Acid of a suitable strength
and quantity (according to the composition of the Ore) which dissolves out the
Zinc, Copper and Silver. This operation is repeated if necessary and the resulting
liquors are partially neutralized with Lime and completed with Chalk or Limestoně
Dust, or altogether neutralized with Chalk or Limestone Dust, as the case may be
according to the composition of the Liquors.
If there remain any Lead not extracted by the first treatment it now separates
as Sulphate together with oxides of Iron and Alumina.
The Liquor after deposition of the Sulphate of Lead and other matters is drawn
off and treated with drainage of Alkali Waste or other Sulphides (as before
mentioned) in exactly sufficient quantity to precipitate as sulphides the Copper,
Silver, and any Lead still remaining.
If necessary this precipitate is treated with hot Hydrochloric Acid which
dissolves out the Lead and converts the Silver into Chloride, the Silver Chloride
is then separated from the Copper Sulphide by a boiling solution of Calcium or
Sodium Chlorides and the Metals precipitated from their respective solutions as
Sulphides or obtained in the metallic state as before mentioned.
The clear liquor from the deposit of Copper and other Sulphides (which deposit
we partially dry by means of a Filter Press) is treated with more alkali waste
liquor, or other sulphides to precipitate the Zinc as white sulphide.
When it is desired to obtain the Zinc as Oxide, the process is varied as follows.
Previous to the completion of the neutralization of the Solution, obtained by
treatment of the calcined ore, with Hydrochloric Acid, there is added sufficient
Bleaching Powder or any cheap oxidizing agent to convert any ferrous iron
present, into the ferric state. The neutralization by Limestone Dust or Chalk is
then completed, and a sufficient quantity added to completely remove from the
solution the Iron Oxide and Alumina. After separation of these by means of a
Filter press, the clear liquor obtained is treated with drainage of alkali waste or
other sulphide in sufficient quantity to throw out the Lead, Copper and Silver.
After deposition of these and pressure of the precipitate the clear liquor is
treated with Milk of Lime in a boiling state in quantity sufficient to throw down
the whole of the Zinc as Oxide;

page_text: SPECIFICATION' in pursuance of the conditions of the Letters Patent filed
by the said James Cross and George Isaac James Wells in the Great Seal
Patent Office on the 10th November 1883.
JAMES CROSS and GEORGE ISAAC JAMES WELLS both of Widnes in the County
of Lancaster "A NEW OR IMPROVED PROCESS FOR THE EXTRACTING OF SILVER,
AND ZINC FROM BLUESTONE
OTHER MIXED
LEAD, COPPER
APPARATUS EMPLOYED THEREIN
T
"
AND
ORES, AND
This invention relates to the treatment of ores containing various metals in
admixture.
The method hitherto adopted in wet processes for the extraction of metals from
complex ores is first to roast the ore with a view to eliminate the sulphur
contained therein and then to extract the metals such as zinc and copper by
hydrochloric acid, sulphuric acid and other agents and afterwards the metals such
as silver and lead, by brine or the chlorides of the alkaline earthy metals, but
these metals are only imperfectly separated by this method.
The Drawings hereunto annexed represent a convenient arrangement of
apparatus we employ in carrying our present invention into effect.
Figure 1 is a plan, Figure 2 is a front elevation and Figure 3 is a cross
section.
The present invention consists in digesting the unroasted ores (reduced to a fine
state of division) in hot hydrochloric acid, in vessels B which we prefer to be of
stone. The lead is then converted into chloride which is soluble in certain
menstrua. The liquor in such vessels B is then partially neutralized with lime or
carbonate of lime but leaving an excess of acid, it is then well boiled, settled and
run off from B whilst hot, through a suitable filter C from which it is raised by
a screw pump D into a trough d whence runs into a tank E where it is allowed
to cool. If a second filtration is found necessary the liquor is allowed to run back
into the filter C suitable sluice valves d² d³ being employed for controlling the
flow of the liquor.
The filter we propose to use is according to our invention made of cakes of soft
peat c laid close together on a sheet of asbestos cloth or other suitable woven
material or on perforated tiles or slabs supported on a wooden or other suitable
platform c¹ in a suitable tank C the filter being kept warm by hot air or steam
and in order to hasten the filtering process we prefer to apply a vacuum to the
underside of the filtering bed but if desired pressure can be applied to the top of
the liquor in the filtering vessel C in which case the latter will require as is well
understood to be made close at the upper part so as to enable the required pressure
to be applied.
The operation of attacking the ore with acid is repeated if necessary until all
the lead is extracted.
The liquor in tank E after being cooled by artificial means or allowed to stand
until sufficiently cooled deposits nearly all of the lead as crystals of chloride of
lead and is then run off into another tank G where the remaining lead in solution
and any silver it may contain in solution are precipitated by the addition of a
solution of soluble sulphide which is conveniently contained in tank O; the
complex sulphide solution obtained from the drainage of alkali waste or a solution
of a similar composition or alkali waste itself is what we use throughout our
process but the former is preferred.
The liquor and precipitate in G are then passed through a filter press I whence
the clear liquor or filtrate passes into the tank J from which it is run to waste..
If however such liquor contain any zinc the latter can be recovered as a white

page_text: sulphide by the further addition of sulphide liquor so long as the black sulphide of
iron redissolves on agitation. Instead however of depositing the lead in the
manner above described as crystals of chloride of lead it may be extracted in the
metallic state by treatment of the liquor with scrap iron by the mode now
extensively used for the extraction of copper.
The residue left in the stone vessels B is there washed with boiling water or
with chloride liquor which is conveniently contained in tanks A and is run
therefrom as required into the stone vessels B, the washed residue is then taken
out from the stone vessels B dried and calcined so as to drive off sulphur which
latter is driven off much more readily from the said residue than from the ore in
its original state.
The calcined ore is now treated in stone vessels B' with hydrochloric acid of a
suitable strength and in proper quantity (according to the composition of the ore)
which dissolves out the zinc, copper and silver contained therein; this operation is
repeated if necessary and the resulting liquors are run into the filtering vessel C¹
for filtration, they are then raised by the screw pump D' into a trough d¹ whence
they are run into a tank El to cool; these cooled liquors are then run into the
vessel or well G' where they are partially neutralized with lime and the
neutralization is completed with chalk or limestone dust, or they are altogether
neutralized with chalk or limestone dust as the case may be according to the
composition of the liquors.
If a second filtration is found necessary the liquor is allowed to run back into
the filter Csuitable sluice valves d d being employed for controlling the flow of
the liquor.
.
The muddy liquor is then passed through filter press I¹ where the precipitates
are separated and the clear solution thence passes into vat J¹ whence it runs into
the vessel or well K. Here it is treated with sulphide liquor (as before mentioned)
in exactly sufficient quantity to precipitate as sulphides the copper silver and any
lead still remaining.
The liquor in the vessel or well K together with the deposit of copper and other
sulphides is passed through filter press N to separate, in a partially dry condition,
the deposit from the liquor which latter runs into the tank M the clear liquor is
then treated in a suitable vessel with more alkali waste liquor or other sulphides
to precipitate the zinc as white sulphide.
If necessary the precipitate obtained from the filter presses I¹ and N is treated
in a suitable stone vessel with hot hydrochloric acid which converts the lead and
silver into chloride, the silver and lead chloride is then separated from the copper
sulphide by a boiling solution of calcium or sodium chlorides.
When it is desired to obtain the zinc as oxide the process is varied as
follows:-
Previous to the completion of the neutralization of the solution in G³ obtained.
by the treatment of the calcined ore with hydrochloric acid there is added
sufficient bleaching powder or any cheap oxidizing agent to convert any ferrous
iron present into the ferric state. The neutralization by limestone dust or chalk
is then completed in G¹ and a sufficient quantity added to completely remove from
the solution the iron oxide and alumina. After separation of these by means of a
filter press I¹ the clear liquor obtained is then treated in K with the sulphide
liquor as before mentioned in sufficient quantity to throw out the lead copper and
silver.
After deposition of these and pressure of the precipitate the clear liquor is
treated in a suitable vessel with milk of lime in a boiling state in quantity
sufficient to throw down the whole of the zinc as oxide.
H H¹ and L represent the positions of the pumps for the presses I I' and M.
Communication is made between the various tanks and vessels as required by
means of suitable channels pipes and cocks whilst the various chambers B B' G G¹
and K are provided with suitable stirrers or agitators to which rotary motion is
given as shewn or by other suitable means.

page_text: The treatment of metallic solutions as above described is the practical appli-
cation of the part of our invention which is essentially that of fractionally
precipitating from complex metallic solutions by means of a decomposable
sulphide, firstly the metals lead copper and silver from zinc and secondly zinc
from iron.
Having thus described the nature of our said invention and the mode in which
we carry the same into effect we would have it understood that we do not confine
ourselves to any particular form of apparatus nor to any specific mode of working
the details of the process but what we claim as our invention is:-
First. The new or improved process for the extracting of silver, lead, copper
and zinc from bluestone and other mixed ores substantially as herein described..
Second. The treatment of raw complex ores with hot hydrochloric acid to
extract the lead.
Third. The treatment of a complex metallic solution with the complex sulphide
solution obtained from the drainage of alkali waste or a solution of similar
composition or alkali waste itself or other decomposable sulphide so as to separate
the metals by fractional precipitation.
Fourth. The novel construction of filter substantially as herein described and
for the purpose stated.
In witness whereof we the said James Cross and George Isaac James Wells
have hereunto set our hands and seals this Fifth day of November in the year of
our Lord. One thousand eight hundred and eighty three.
JAMES CROSS