IMPROVEMENTS IN THE TREATMENT OF ORES OR METALLIC MIXTURES AND IN APPARATUS THEREFOR
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 IMPROVEMENTS IN
THE TREATMENT OF ORES OR METALLIC MIXTURES AND IN APPARATUS
THEREFOR
PROVISIONAL SPECIFICATION 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 IMPROVEMENTS IN THE TREATMENT OF ORES OR METALLIC MIXTURES
AND IN APPARATUS THEREFOR
This Invention relates to improvements in treating ores and metallic mixtures of
lead and zinc either with or without the admixture of silver or copper or other
metal or metals and in apparatus therefor and is founded in part upon the
improvements described in the Specifications of previous Patents granted to
F. Maxwell Lyte and dated respectively 15th February 1877 N° 633, 23rd July 1877
N° 2807, 22nd January 1879 N° 269, 10th March 1880 N° 1051, and 26th November
1880 N° 4932 and our present improvements relate to apparatus to be used in the
systematic treatment of some of such ores as are referred to in the Specifications
above mentioned and to a systematic treatment of the said ores so as to ensure
more advantageous result by the extraction of the metallic constituents at
diminished cost more rapidly and in a more readily available form.
The ores to which the invention specially applies are those consisting of
mixtures or compounds of sulphides of lead and sulphides of zinc with other
metals or with sulphides or oxides of other metals which have not been hitherto
successfully treated on a commercial scale by any process other than those included
in the Patents hereinbefore referred to and the apparatus is specially adapted
to the treatment of these ores but it is also in part applicable to the treatment
of other Ores whether mixed or not,
We will first describe the process as applied to an ore consisting of mixed lead
and zinc sulphide.
After the ore has been powdered it is necessary to calcine it as directed in
.

page_text: the Specifications of Patents herein before referred to; the object of this calcination
being to drive off the greater part or all of the combined or free sulphur so as to
leave the metals which are present as far as possible in the form of oxides.
This calcination is a somewhat difficult process and we have found that it is
best to calcine the powdered ore in a revolving calciner, constructed in such a
way that the ore being repeatedly lifted by convenient arrangements during its
passage through the calciner and allowed to fall through a current of hot air and
flame proceeding from a suitable furnace may be exposed repeatedly in a fine state
of division to the action of the gases proceeding from the furnace.
To carry this out in practice we make a closed furnace adapted for burning coal
or slack provided with suitable doors and other openings as hereinafter described.
In the front part of the furnace there are suitable apertures provided with doors
for regulating the admission of air, first, below the fire bars into the ash pit,
secondly immediatly or nearly so upon the top of the bars or bed plate in front of
the bars this opening being so constructed that it forms an ordinary fire door
capable of being used for firing and is also capable of adjustment so as to allow a
certain amount of draught of air when necessary to pass through it, and thirdly at
an elevation of a few inches above the level of the burning fuel on the fire bars so
that an excess of atmospheric air can be allowed to pass through the furnace over
the top of the incandescent fuel whenever necessary.
"
At the back of this furnace we construct a circular opening or flue with the
necessary fittings to connect it to a " revolver or revolving calciner constructed as
hereinafter described and we make another opening below this circular one leading
into a close chamber or reservoir which we construct by preference at the back or
side of the ash pit of the furnace in order to receive and collect the calcined ore.
This chamber is provided with doors to enable the collected contents of calcined
ore to be removed from time to time.
The revolver which we prefer to use is somewhat similar to a "black ash
revolver" and consists of a tube of iron supported upon wheels or rollers in a
sloping position with its lowest end near to the furnace and provided with driving
gear and machinery so as to be capable of rotation on its own axis at a requisite
speed. This iron tube is lined with fire brick or other refractory lining to protect
it from the heat and at intervals projecting bricks or pieces of fire clay are so
placed that they lift the powdered ore by the rotation of the revolver and drop it
again through the current of hot air and flame after a certain portion of the
rotation.
07
At the 'upper end this revolver is. adjusted to a circular opening in a chamber
connected with a chimney or other source of draught and this chamber (which is
constructed of fire brick or other refractory material) serves three different
purposes, first, in the top of the chamber there is fixed a hopper through which the
powdered ore is allowed to run slowly into the revolver and is there calcined and
finally delivered into the closed chamber or receiver at the lower end of the
revolver at the back of the furnace.
Secondly. The lower. part of the chamber forms a pocket to catch and retain
most of the calcined ore which may be blown or drawn over by the draught.
Thirdly. The further side of the chamber forms the outlet or chimney of the
revolver and is connected to a flue leading to a chimney or some other suitable
source of draught. A suitable chamber or condenser being interposed to intercept
the gases.
The mode of using this calciner is to feed the powdered ore through the hopper
in a steady regulated stream (the amount of which must be determined by previous
experiment) into the revolving calciner and to adjust the furnace and the draught
so that during the passage of. the powdered ore through the revolver the sulphur
shall be so far eliminated as to bring the ore into a state fit for subsequent
treatment by this process while the draught shall not be so excessive as to cause
waste of ore or allow it to be drawn into the chimney.
:

page_text: This calcined and powdered ore is, then transferred to the attacking tub or
cistern for treatment with hydrochloric acid as described in the specifications of the
Patents hereinbefore referred to but we have found it advantageous to modify the.
construction of the attacking tubs or cisterns. We prefer to construct them of
stone slabs jointed together in a special way with india rubber.
We will describe the manner in which we prefer to construct an attacking cistern
suitable for the treatment of such an ore as that hereinbefore referred to..)
We take a slab of stone of 9 inches in thickness to form the bottom of the attacking
cistern and we take 6 or 8 or 10 slabs of stone to form the sides each of them of
7 inches thickness.
་ ་
The stone must be of such a character that it is practically unacted upon by:
boiling solutions of hydrochloric acid and salt. Stone from many of the Yorkshire
quarries answers well.
The slabs of stone forming the sides of the attacking cistern are fitted one to
another and they all fit to the bottom to form a vessel having a flat bottom with 6
or 8 sides or of other form as the case may be.
In order to make this attacking cistern thus constructed acid tight and prevent
the leakage of the liquors from it each of the edges where they meet one another
and the bottoms of the sides where they meet the stone bottom must be grooved in
such a way that a piece of solid india rubber or other suitable substance may be
pressed into the groove and squeezed between the stone sides and bottom as the
case may be so as to make a water tight joint and leave as little as possible of the
india rubber itself exposed to the action of the acid and the whole of the pieces of
stone forming the sides must then be clamped together.
In treating ores containing much lead we find that it is essential to maintain the
heat of the acid solutions in the attacking cistern and of the brine solutions in the
attacking cisterns as nearly as possible at boiling point and for this purpose we
provide these stone attacking tubs with suitable pipes conveying live steam of high
pressure and covers so as to retain the heating effect of this steam. We also jacket
these cisterns and apply heated air or steam to the same.
It is desirable that the acid or brine liquor after the attack should be drawn off
from the attacking cistern at the highest temperature which is possible after the
gangue has settled.
But when these liquors are drawn off they contain metallic chlorides in solution
which are held in solution mainly owing to the temperature of the liquor and it is
therefore desirable to cool them as quickly and economically as possible in order to
separate the metallic chlorides contained in them.
In the specification of patent N° 1051 of 1880 one method is described which we
propose to employ for cooling these liquors namely that of the use of compressed
air but we find that in many cases it is more advantageous to employ open troughs
through which acid brine or liquor is allowed to run with a very small depth and
exposing a large surface to the action of the atmosphere so that the evaporation
may cause the reduction of the temperature to a sufficient extent to enable the
crystallized chloride of lead or other salt to be deposited more rapidly in the
crystallizing tanks into which the liquor runs after leaving the attacking
cisterns.
These cooling troughs are interposed in the course of the liquor between the
attacking cisterns and the crystallizing tanks.
It is desirable if not essential in connection with this process that the silver (if
any is contained in the ore) should be extracted and methods by which this may
be done, namely by treating the acidulated liquor with zinc are described in the
specifications herein before referred to, but we find that it is advantageous that the
solution containing the silver should be kept continually in circulation by some
suitable means in order to bring all particles of the solution in contact with the
zinc, so that that zinc reducing the salts of lead contained in the solution would
form a spongy lead and may more rapidly absorb the silver which may be present
in the solution.

page_text: The apparatus we employ for this purpose consists of a vat to receive the
solution. In this vat is fitted a vertical tube in which a screw is caused to rotate
and thereby lift the solution and discharge it into the first of a number of shallow
troughs in which the solution passes to and fro until it is finally returned to the
vat. Within these troughs are placed or fixed pieces of zinc or spelter which
intercept the solution and cause every particle thereof to come into contact with
the zinc or spelter.
When the solution has been sufficiently de-silverized it is again raised and run
by another trough or "launder" into receiving or stock tanks.
In reference to the zinc oxide we prefer to separate the water by means of a
filter press.

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 "IMPROVEMENTS IN THE TREATMENT OF ORES OR METALLIC MIXTURES
AND IN APPARATUS THEREFOR
This invention relates to improvements in treating ores and metallic mixtures of
lead and zinc either with or without the admixture of silver or copper or other
metal or metals and in apparatus therefor and is founded in part upon the
improvements described in the specifications of previous Patents granted' to
Farnham Maxwell Lyte and dated respectively 15th February 1877 N° 633,
23rd July 1877 N° 2807, 22nd January 1879 N° 269, 10th March 1880 N° 1051
and 26th November 1880 N° 4932 and our present improvements relate to apparatus
to be used in the systematic treatment of some of such ores as are referred to in
the specifications above mentioned and to a systematic treatment of the said ores
so as to ensure more advantageous results by the extraction of the metallic con-
stituents at diminished cost more rapidly and in a more readily available form.
The ores to which the invention specially applies are those consisting of mixtures
or compounds of sulphides of lead and sulphides of zinc with other metals or with
sulphides or oxides of other metals which have not been hitherto successfully,
treated on a commercial scale by any process other than those included in the
Patents bereinbefore referred to and the apparatus is specially adapted to the
treatment of these ores but it is also in part applicable to the treatment of other
ores whether mixed or not.
We will first describe the process as applied to an ore consisting of mixed lead
and zinc sulphide.
After the ore has been powdered it is necessary to calcine it as directed in the
specifications of Patents herein before referred to the object of this calcination
being to drive off the greater part or all of the combined or free sulphur so as to
leave the metals which are present as far as possible in the form of oxides. This
calcination is a somewhat difficult operation and we have found that it is best to
calcine the powdered ore in a revolving calciner constructed in such a way that the
ore being repeatedly lifted by convenient arrangements during its passage through
the calciner and allowed to fall through a current of hot air and flame proceeding
from a suitable furnace may be exposed repeatedly in a fine state of division to the
action of the gases proceeding from the furnace.
To carry this out in practice we adopt the arrangement represented at Figures 1
and 2 in which we use a closed furnace adapted for burning coal or slack
provided with suitable doors and other openings as hereinafter described. In the
front part of the furnace a there are suitable apertures a¹. a. a³ provided with
doors for regulating the admission of air; first (a¹) below the fire bars into the ash
pit, secondly (a) immediately or nearly so upon the top of the bars or bed plate
in front of the bars this opening a² being so constructed that it forms an ordinary
fire door capable of being used for firing and is also capable of adjustment so as to
allow a certain amount of draught of air when necessary to pass through it and a
few inches above the level of the burning fuel on the fire bars so that an excess of
atmospheric air can be allowed to pass through the furnace over the top of the
incandescent fuel whenever necessary, and thirdly (a³) above the top of the furnace
for sight hole and to admit air.
•
At the back of this furnace a we construct a circular opening or flue a' with

page_text: the necessary fittings to connect it to a "revolver" or revolving calciner con-
structed as hereinafter described and we make another opening a5 below this
circular one a leading into a close chamber or reservoir a6 which we construct by
preference at the back or side of the ash pit of the furnace in order to receive and
collect the calcined ore.
This chamber a is provided with doors to enable the collected contents of
calcined ore to be removed from time to time.
"black ash
The revolver which we prefer to use is somewhat similar to a
revolver" and consists of a tube b of iron supported upon wheels or rollers 6² in a
sloping position with its lowest end near to the furnace a and provided with
driving gear and machinery as shown so as to be capable of rotation on its own
axis at a requisite speed. This iron tube b is lined with fire brick or other
refractory lining to protect it from the heat and at intervals projecting bricks or
blocks 6 of fire clay are so placed that they lift the powdered ore by the rotation
of the revolver and drop it again through the current of hot air and flame after a
certain portion of the rotation. Thus far the calcining apparatus is similar to that
known as the Oxland and Hocking calciner used for roasting copper tin and other
ores containing sulphur, arsenic and other volatile matters:
At the upper end this revolver is adjusted to a circular opening in a chamber c
connected with a chimney d or other source of draught and this chamber c (which
is constructed of fire brick or other refractory material) serves three different
purposes, first, in the top of the chamber there is fixed a hopper c¹ through which
the powdered ore is allowed to run slowly into the revolver and is there calcined
and finally delivered into the closed chamber or receiver a at the lower end of the
revolver at the back of the furnace.
'
Secondly The lower part of the chamber forms a pocket c² to catch and retain
most of the calcined ore which may be blown or drawn over by the draught.
Thirdly. The further side of the chamber c forms the outlet or chimney of the
revolver and is connected to a flue leading to the chimney d or some other suitable
source of draught a suitable chamber. or condenser es being interposed to abstract
the sulphurous acid gas.
This chamber or condenser c³ is provided with circuitous passages formed by a
number of trays or shelves ct as shown on which is placed oxide of iron or other
suitable absorbent.
The mode of using this calciner is to feed the powdered ore through the
hopper c' in a steady regulated stream (at a rate to be determined by previous
experiment) into the revolving calciner b and to adjust the furnace and the draught
so that during the passage of the powdered ore through the revolver the sulphur
shall be so far eliminated as to bring the ore into a state fit for subsequent
treatment by this process while the draught shall not be so excessive as to cause
waste of air or allow it to be drawn into the chimney d.
This calcined and powdered ore is then transferred to the attacking tub or
cistern E for treatment with hydrochloric acid as described in the specifications of
the Patents hereinbefore referred to but we have found it advantageous to modify
.the construction of the attacking tubs or cisterns. We prefer to construct them of
stone slabs jointed together in a special way with india rubber as represented at
Figures 3 and 4 which are respectively a plan and side elevation.
We will describe the manner in which we prefer to construct an attacking
cistern suitable for the treatment of such an ore as that herein before referred to.
We take a slab e of stone of 9 inches in thickness to form the bottom of the
'attacking cistern and we take 6 or 8 or 10 slabs e' of stone to form the sides each
of them of 6 inches thickness. The stone must be of such a character that it is
practically unacted upon by boiling solutions of hydrochloric acid and salt. Stone
from many of the Yorkshire quarries and known as Yorkshire stone answers well.
The slabs of stone forming the sides e' of the attacking cistern are fitted one to
another and they all fit to the bottom to form a vessel having a flat bottom with
6 or 8 sides or of other form as the case may be. --

page_text: In order to make this attacking cistern thus constructed acid tight and prevent
the leakage of the liquors from it each of the edges where they meet one another
and the bottoms of the sides where they meet the stone bottom must be grooved
in such a way that a piece of solid india rubber cord e³ or other suitable substance
may be pressed into the groove and squeezed between the stone sides and bottom
as the case may be so as to make a watertight joint and leave as little as possible
of the india rubber itself exposed to the action of the acid and the whole of the
pieces of stone forming the sides must then be clamped together. We do not
however lay claim to this construction of attacking cistern as such is well known
for other purposes.
In treating ores containing much lead we find that it is essential to maintain the
heat of the acid solutions in the attacking cisterns and of the brine solutions in
the attacking cisterns as nearly as possible at boiling point and for this purpose
we provide these stone attacking tubs with suitable pipes (not shown) conveying
live steam of high pressure and covers so as to retain the heating effect of this
steam without however being steam tight. We also jacket these cisterns and
apply heated air or steam to the space between the jacket and cistern as will be
well understood.
It is desirable that the acid or brine liquor after the attack should be drawn off
from the attacking cistern at the highest temperature which is possible after the
gangue has settled..
But when these liquors are drawn off they contain metallic chlorides in solution
which are held in solution mainly owing to the temperature of the liquor and it
is therefore desirable to cool them as quickly and economically as possible in order
to separate the metallic chlorides contained in them.
In the specification of Patent N° 1051 of 1880 one method is described which
we propose to employ for cooling these liquors, namely, that of the use of compressed
air but we find that in many cases it is more advantageous to employ .open
troughs see Figure 5 through which acid brine or liquor is allowed to run with a
very small depth and exposing a large surface to the action of the atmosphere so
that the evaporation may cause the reduction of the temperature to a sufficient
extent to enable the crystallized chloride of lead or other salt to be deposited more
rapidly in the crystallizing tanks G into which the liquor runs after leaving the
attacking cisterns E. These cooling troughs are interposed in the course of the
liquor between the attacking cisterns E and the crystallizing tanks G
It is desirable if not essential in connection with this process that the silver (if
any is contained in the ore) should be extracted and methods by which this may be
done namely by treating the acidulated liquor with zinc are described in the
specifications herein before referred to but we find that it is advantageous that the
solution containing the silver should be kept continually in circulation by some
suitable means in order to bring all particles of the solution in contact with the
zinc so that zinc reducing the salts of lead contained in the solution would form
a spongy lead and may more rapidly abstract the silver which may be present in
the solution.
The apparatus we employ for this purpose is represented at Figures 5 and 6 and
consists of a vat H to receive the solution. In this vat is fitted a vertical tube h
in which a screw h' is caused to rotate and thereby lift the solution and discharge
it into the first of a number of shallow troughs h² in which the solution passes to
and fro until it is finally returned to the vat. Within these troughs are placed or
fixed pieces of zinc or spelter which intercept the solution and cause every particle
thereof to come into contact with the zinc or spelter.
When the solution has been sufficiently de-silverized it is again raised and run
by the last of the troughs or launders h³ into receiving or stop tanks I suitable
sluice valves being employed to direct the solution from the troughs or launders h³
into the vat H or I as may be required.
In reference to the zinc oxide we prefer to separate the greater portion of the
water by means of a filter press.

page_text: 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 what we
claim is :-
First The process and apparatus for calcining ores or metallic mixtures by a
revolving calciner connected with a chamber c formed with a pocket c² and
condenser substantially as herein shown and described and for the purpose
stated.
Second The process and apparatus for rapidly cooling the liquors drawn off
from the attacking cistern by causing the said liquors to circulate in a series of
shallow troughs substantially as herein shown and described and for the purpose
stated
Third-The process and apparatus for maintaining a circulation of the acidulated
liquor or solution in order to bring all particles of the solution into contact with
zinc immersed therein substantially as herein shown and 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.