AN IMPROVED PROCESS FOR OBTAINING ZINC FROM ITS ORE AND FROM OTHER MATERIALS
Year: 1881

page_text: LETTERS PATENT to Henry Harris Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of "AN IMPROVED PROCESS FOR OBTAINING ZINC FROM ITS ORE AND FROM
OTHER MATERIALS." A communication from abroad by Léon Létrange, of
Paris France. Manufacturer.
PROVISIONAL SPECIFICATION left by the said Henry Harris Lake at
the Office of the Commissioners of Patents on the 22nd July 1881.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS FOR OBTAINING
ZINC FROM ITS ORE AND FROM OTHER MATERIALS." [A communication from
abroad by Léon Létrange, of Paris, France, Manufacturer.]
This Invention relates to an improved process for reducing to the metallic stato
by means of electricity the zinc contained in ores or in other materials produced in
manufacturing processes.
This process, which was not possible when electricity was produced only by the
dissolution of zinc by an acid, now becomes practicable and economical, as electricity
may be obtained abundantly without other expenditure than that required to
procure motive power.
Zinc ores in their natural state are ordinarily found in two forms, viz., as blende
(sulphuret of zinc), or as calamine (carbonate of zinc). Blende is ordinarily roasted
for the purpose of converting the same into oxide by expelling the sulphur. The
latter is very seldom collected, being ordinarily allowed to escape into the
atmosphere in the form of sulphurous acid vapor, to the great peril of the vegetation
and the health of human beings in the neighbourhood. This inconvenience renders
the treatment of blende impossible in many places.
Calamine, if it has to be treated at a very great distance from the mine, is
converted into oxide by calcination, which has for its object to expel the carbonic
acid so as to diminish its weight and to economise, in proportion to such reduction,
the cost of transport. The ore being thus reduced to the state of an oxide is

page_text: subjected in closed vessels, and for a considerable length of time, to a high tem-
perature in a great number of delicate apparatus, in which the zine is imperfectly
collected by distillation. This treatment has the following disadvantages,
viz-
The quantity of coal required for the reduction being almost twice the weight of
the ore, the zinc-works have to be established near to coal-mines, and the ore has
to be brought there, which entails frequently very high cost of transport.
The fuel forms an important item in the expenses of treatment.
The consumption of refractory material constantly requiring to be renewed is
somewhat considerable.
The manual labor is rendered expensive and difficult by the very arduous
operations requiring great skill on the part of the workinen.
A considerable part of the zinc contained in the ore (from one fifth to one sixth)
is not collected in the processes at present in use, and is consequently lost.
The establishment of zinc-works requires a very considerable first expense, and
the operations cannot economically be worked on a small scale; moreover, they are
very inconvenient for the neighborhood.
All the inconveniences which I have above indicated are avoided by the process
to which this Invention relates.
The said Invention is carried into practice as follows, that is to say :-
If I have blende to treat I first roast it, but instead of expelling the sulphur by
rapid roasting and a very hot fire so as to decompose the sulphates which are
formed, I conduct the operation at a very moderate temperature, and with such
precautions as are necessary for transforming the sulphuret of zinc into sulphate of
zinc, allowing as little sulphur to escape into the air as possible. I may even use
calamine for absorbing, either in the roasting furnace itself or in a tower placed in
the path of the fumes (between the furnace and the chimney), the sulphurous acid
and sulphuric acid that are produced by the roasting.
The sulphate of zinc thus produced by the roasting of the blende is dissolved in
water and subjected to the decomposing action of an electric current, which
precipitates the zinc in a metallic state, and renders the acid derived from the
decoinposed salt available for use.
When blende alone is treated a large quantity of sulphuric acid will be produced
which may be profitably used apart from the treatment of zinc.
But this acid may
_ also be again used an indefinite number of times for dissolving fresh quantities of
oxide of zinc.
. When calamines or oxides of zinc are treated it will suffice to introduce in their
treatment such a quantity of blende as will furnish, by the process I have herein-
before described, the quantity of sulphuric acid requisite to the formation of the
permanent bath of sulphate of zinc, and also for compensating for the losses caused
by combination with the foreign matters contained in the ores, or by absorption of
the residues.
'
In all cases I am enabled to collect from the residues lead, silver, and other
useful matters which the ore contains.
The apparatus required for reducing to the metallic state sulphates and oxides of
zinc are the following, that is to say -
A series of basins or reservoirs in which the material containing the zinc is
transformed into sulphate.
">
A motor-engine.
A "Gramme
a prime motor.
or any
other machine capable of producing electricity by means of
A second series of basins or reservoirs in which the precipitations of the zinc is
effected by the action of the electric current.
The ore consisting either of blende roasted in the hereinbefore indicated manner,
or of a mixture in definite proportions of blende, and of calamine or oxide of zinc
is placed into any number of vessels which communicate. This apparatus may be
arranged in various ways, one of which is as follows:-

page_text: I will assume the apparatus to consist of four basins or reservoirs made of
brick work and lined with bitumen in their interior, so that they may be quite
watertight. They communicate with one another by means of pipes, which receive
the liquid at the bottom of each reservoir and deliver it at the top of the next one,
the latter containing somewhat less of the liquid.
The basins or reservoirs may if desired be five or more in number, and arranged
in a circle or parallel to each other.
The four reservoirs hereinbefore mentioned being filled with ore, I pour into the
first one the acidulated liquor, which dissolves the oxide of zinc, and then
successively passes into each of the other reservoirs, leaving the last one completely
saturated with sulphate of zinc.
When the ore in the first reservoir which receives the acid liquid is altogether
deprived of the oxide of zinc, its communication with the second reservoir is cut
off, so that the first may be emptied and refilled. The acid water is then intro-
duced into the second reservoir. When the first basin or reservoir is refilled, it
is put in communication with the last one, and then the sulphate flows out of
the apparatus from the first one. The second reservoir which thus becomes the :
first is in its turn cut out of the circuit or course for being emptied and refilled,
and the third reservoir becomes the first.
The operation is thus continued for each of the reservoirs; each one after having
been the last, vist, the one in which the liquid becomes completely saturated with
sulphate of zinc, advances in order to become the first, exhausting its ore by
receiving the acid after having been cut out of the current of the liquid for being
emptied and re-charged. The water charged with sulphate of zinc, which leaves
the above described apparatus, then flows into another reservoir which serves for
regularly feeding another set of basins or reservoirs, in which the zinc is to be
precipitated by electricity.
This intermediate reservoir is placed at a level lower than that of the first named
or dissolving reservoirs, so as to receive the produce of the latter by simple gravity.
In this intermediate reservoir or in specially arranged reservoirs connected there-
with, the sulphate of zine may be purified by known processes from foreign matter
which it may be profitable to collect, or which may advantageously be eliminated
so that zinc free from any admixture may be produced.
The lead and silver which are very frequently found in zinc ore are not lost, as
is the case in the dry process.
They are collected in the residues from the dissolution which are withdrawn
from the reservoirs, and which are if necessary heated by special methods.
The reservoirs of the second set consist of wooden vats lined with lead, of glass,
sandstone, brick work lined with bitumen, or of any other material capable of
resisting the corrosive action of sulphuric acid.
In these reservoirs are placed a series of thin sheets of zinc which serve as
cathodes upon which the zine is precipitated, and the surface of which must be
proportioned according to the electric power which is employed, and according to
the quantity of zinc to be deposited.
The cathodes may be of copper or of polished brass from which the zinc deposited
thereon can easily be detached.
In front of each cathode I place an anode of carbon or of other material which is
a conductor of electricity, and naturally insoluble in sulphuric acid or coated so as
to be insoluble therein.
For producing zinc by my process any arrangements may be used which are
applied for depositing other metals by means of electricity.
•
The solution of sulphate of zinc is by dip-pipes conveyed to the bottom of the
precipitating reservoirs in a regular manner and in determined quantities.
The zinc which is precipitated in the metallic state on the cathodes by this
decomposition of the sulphate sets free a proportionate quantity of sulphuric acid,
which goes to the upper part of the bath above the sulphate which possesses a
greater density.

page_text: The upper part of the bath which becomes continually acid is emptied by outflow
through openings provided for the purpose, and in proportion as sulphate is
introduced at the bottom of the reservoir.
This sulphate is designed to replace it in restoring zinc to the bath in the same
degree as it is abstracted therefrom by precipitation.
"By means of this continuous stream. the sulphate bath is maintained at the
most suitable degree of concentration and acidity and the production of zinc is
regular.
The acid liquid, which is exhausted from the upper part of the bath, is allowed
to pass directly to the heaps of ore, or preferably into a special reservoir, where the
degree of its acidity can be controlled at all times.
The precipitating reservoirs can be placed at a level lower than that of the
intermediate reservoir, and the acid from the precipitating reservoirs is raised by a
pump to another reservoir; or the precipitating reservoirs may be higher than the
intermediate reservoir, and then a pump is used; when the precipitating reservoirs
are above the reservoir for receiving the acid the acid flows naturally into the
same.
In cases where blende is specially designed to be treated and the treatment
produces a quantity of acid which the ore is incapable of absorbing the excess of
acid is taken from this reservoir to be used in any manufacture, or is reduced
to a condition suitable for commercial purposes by the ordinary well known
processes.
In some cases, and more especially when very pure calamine is to be treated, or
in the treatment of oxides of zinc produced in the fusion of metal, the above
described arrangements may be simplified. In this case the ore or the ash is
dissolved in the same reservoir in which the zinc is precipitated under the action
of the electric current.
For this purpose the plant comprises in addition to the motor engine and the
electric machine only one series of receivers coupled together and serving to
receive, one the anode surrounded by the material to be attacked, the other the
cathode upon which the zinc is to be precipitated. The one of the recipients
contained within the other has to be made of some porous material, such as
porcelain, stone, terra cotta, or woven fabric, so as to prevent the deposited zinc
being soiled by the ore.
Or I may use long basins or reservoirs divided in the interior by porous
partitions, between which are placed alternately the anodes surrounded-by-oro-and-
the cathodes upon which the zinc is deposited.
The apparatus thus construed is placed in connection with the electric machine
by conducting wires in the manner practised in metal plating.
In all cases the number of the surfaces of the anodes and cathodes has to be
increased sufficiently to exhaust the power of the electric current, so as to obtain
therefrom the maximum production, and the porous partitions or vessels have to be
removable so as to facilitate the periodical cleaning out of the accumulating
residues.
The ore, or the oxide of zinc, which are bad conductors of electricity, are
mixed with a small quantity of carbon, which, being a good conductor of
electricity, connects the anode with the whole mass and facilitates its disso-
lution.
If zinc-ash, or skimmings or residues of the fusion of zinc, are to be treated,
the quantity of metal contained therein will form a soluble anode and contribute
to the increase of the deposition of zinc on the cathode.
1
A "gramme," or any other machine generating electricity by means of motive
power, transmits electricity by conducting wires into the special workshop in which
the precipitating reservoirs are situated.
The machine for producing the electricity is set in motion when required by
steam, or preferably by a water course, which is frequently found in proximity to
mines.

page_text: The said process is characterized by the following features, viz. :-The use of
electricity for treating zinc ores; the production of electricity for this purpose by
motive power; the treatment by the wet process of zinc ores for manufacturing
purposes; the extraction of the sulphuric acid required for its dissolution from the
ore itself; the utilization of all the useful materials contained in the ore; and the
production of absolutely pure zinc.
F
The advantages my process offers when compared with the usual process of
distilling are as follows, viz. :-
The roasting of the blende at a very low temperature for producing sulphates is
much less costly than heretofore in use, in which great heat has to be applied for
decomposing the sulphates, the formation of which cannot be avoided. In the very
rare cases in which a steam engine will have to be used I require a quantity of
coal for each hundred kilogrammes of produced zinc, which is almost equal to that
required in distillation for each hundred kilogrammes of ore, but the expense for
coal is nil when a hydraulic motor is available. The consumption of refractory
material in comparison to that in the distilling process is almost nil. The manual
labor is of much less importance and is less difficult, consequently it is less
expensive. The deficit in the quantity of zinc obtained is reduced. The lead,
silver, and all useful materials contained in the ore are collected. I produce an
excess of acid which can be utilized. The treatment of the ore at the mines
produces considerable economy with respect to transport; I can, by treating them
at the mines, utilize poor ores which cannot bear the heavy expense for transport
and treatment in the dry process, and the zinc produced even from impure ores is
a new product purer than that furnished by distillation; it is consequently of
greater value.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Harris Lake in the Great Seal Patent Office on the
21st January 1882.
HENRY HARRIS LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS FOR OBTAINING
ZINC FROM ITS ORE AND FROM OTHER MATERIALS." A communication from
abroad by Léon Létrange, of Paris, France, Manufacturer.
This Invention relates to an improved process for reducing to a metallic state by
means of electricity the zinc contained in ores or all zineiferous materials produced
in manufacturing processes.
This improved process, which was impracticable when clectricity could only be
produced by the dissolution of zinc in an acid, is now practicable and economical, as
the requisite amount of electricity may be obtained without other expenditure than
that required for motive power.
Zinc ores in their natural state are ordinarily found in two forms, namely, as
blende (sulphide of zinc) or as calamine (carbonate of zinc). Blende is ordinarily
roasted or calcined in order to convert the same into oxide by the expulsion of the
sulphur. The latter is very seldom collected, being ordinarily allowed to escape
into the atmosphere in the form of sulphurous acid vapor, to the great detriment
of the vegetation and the health of persons dwelling in the neighbourhood. This
inconvenience renders the treatment of blende impossible in many localities.
Calamine, if it has to be treated at a very great distance from the mine, is con-
verted into oxide by calcination in order to expel the carbonic acid, so as to reduce
its weight and economise in proportion to such reduction the cost of transport.
The ore being thus reduced to the state of an oxide is subjected for a considerable
length of time to a high temperature in a series of closed vessels, in which the zinc
is imperfectly collected by distillation. This treatment has the following dis-
advantages, namely:-The quantity of coal or fuel required for the reduction being
nearly double the weight of the ore, the zinc-works must, in order to ensure
economical working, be-established-near-a-coal-mine,_and_the_ore must be brought
there;
this necessity frequently entails a very great expense for carriage; the fuel
forms an important item in the expenses of treatment, and the consumption of
refractory material, which constantly requires to be renewed, is considerable.
The manual labour is rendered expensive and difficult by reason of the very
arduous operations, requiring great skill on the part of the workmen.
A considerable part of the zinc contained in the ore (from one sixth to one fifth)
is not collected in the processes at present in use, and is consequently lost.
The establishment of zinc-works requires a very considerable outlay, and the
operations cannot economically be worked on a small scale; moreover they are a
nuisance to the neighbourhood.
All the inconveniences above indicated are obviated by my improved process,
which is carried into practice as follows, that is to say:-
If blende is to be treated I first roast or calcine the same, but instead of expelling
the sulphur by rapid roasting and a very intense fire, so as to decompose the
sulphates which are formed, I conduct the operation at a very moderate tem-
perature and with such precautions as are necessary for transforming the sulphide
of zinc into sulphate of zinc, allowing as little sulphur to escape into the atmosphere
as possible. I may even use calamine for absorbing, either in the roasting or
calcining furnace or in a tower placed in the path of the fumes (between the furnace
and the chimney), the sulphurous acid and sulphuric acid that are produced by the
roasting or calcining. I may employ for the roasting of the material any suitable

page_text: form of apparatus, such as a reverberatory or other furnace, or the said material
may be roasted in heaps.
The sulphate of zinc thus produced by the roasting of the blende is dissolved in
water and subjected to the decomposing action of an electric current, which preci-
pitates the zinc in a metallic state and renders the acid derived from the decomposed
salt available for use.
When blende alone is treated a large quantity of sulphuric will be produced,
which may be profitably used apart from the treatment of zinc. This acid may
however be again used an indefinite number of times for dissolving fresh quantities
of oxide of zinc.
When calamine or oxides of zinc are treated it will suffice to introduce in their
treatment such a quantity of blende as. will furnish by my improved process the
quantity of sulphuric or sulphurous acid requisite for the formation of a permanent
bath of sulphate or sulphite of zinc, and also for compensating for the losses caused
by combination with the foreign matters contained in the ores or by absorption of
the residues.
In all cases I am enabled to collect or recover from the residues, lead, silver, and
other useful materials which the ore contains.
The apparatus required for reducing to the metallic state sulphates and oxides of
zinc are as follow, that is to say:-A series of vessels or reservoirs in which the
zinciferous material is transformed into sulphate, a motor or driving engine, a
'Gramme," or any other machine capable of producing electricity by the employ-
ment of a motor or mechanical energy, and a second series of vessels or reservoirs
in which the precipitation of the zinc is effected by the action of the electric
"
current.
In carrying the said Invention into practice the ore, consisting either of blende
roasted in the manner described, or of a mixture in definite proportions of blende,
and calamine, or oxide of zinc, is placed into any suitable number of vessels which
communicate with each other. This apparatus may be arranged in various
manners, one of which is shewn in the accompanying Drawing, in which
Figure 1 is
vertical section, and
Figure 2, a plan.
Figures 3 and 4 are diagrams, hereinafter described.
In Figures 1 and 2 the apparatus is shewn as provided with four vessels or
reservoirs A, A', A2, A³, which are preferably formed of brickwork or masonry
and lined with bitumen, so as to render them perfectly water-tight. These vessels
communicate with one another by means of pipes a, a, which receive the liquid at
the bottom of each reservoir and deliver it at the top of the next reservoir, which
contains a somewhat less quantity of the liquid.
The vessels or reservoirs may if desired be five or more in number, arranged in
a circle as in Figure 3, or parallel to each other, as indicated in Figure 4.
When the four vessels or reservoirs A, A1, A2, A3, are filled with ore I pour into
the first vessel A the acidulated liquid which dissolves the oxide of zinc, and then
successively passes into each of the other reservoirs A¹, A2, A3, and passes out of
the last one completely saturated with sulphate or sulphite of zinc according to
whether sulphuric or sulphurous acid is employed.
When the ore in the first reservoir A, which receives the acid liquid, is altogether
deprived of the oxide of zinc, its communication with the second reservoir A¹ is
cut off, so that it may be emptied and refilled. The acid water is then introduced
into the reservoir A'. When the vessel or reservoir A is refilled it is put in com-
munication with the last vessel A", and then the sulphate flows out of the
apparatus from the vessel A. The reservoir A', which thus becomes the first, is in
its turn cut out of the current or course of the liquid, to enable it to be emptied
and refilled, and the reservoir A² becomes the first. The operation is thus
successively continued for each of the reservoirs, so that each one after having
constituted the last reservoir, namely, the one in which the liquid becomes completely
saturated with sulphate of zinc advances in order to become the first, exhausting

page_text: its ore by receiving the acid liquid after having been cut out of the current of the
liquid to enable it to be emptied and recharged with ore.
The water charged with sulphate of zinc, which leaves the above described
apparatus, flows into a reservoir B which serves for regularly feeding the vessels
or reservoirs C, C, in which the zinc is to be precipitated by electricity.
This reservoir B is placed on a lower level than that of the vessels or reservoirs
A, A1, A2, A3, so as to receive the produce of the latter simply by gravitation. In
this reservoir, or in specially arranged reservoirs connected therewith, the sulphate-
of zinc may be purified by known processes from foreign matters which it may be
profitable to recover, or which may with advantage be eliminated in order to
produce zine free from any admixture. The lead and silver which are very
frequently found in zinc ore are not lost, as is the case in the dry process. They
are collected in the residues from the dissolution which are withdrawn from the
reservoirs, and which are if necessary subjected to a special treatment.
-
As a continuation of the apparatus above described, in which the zinc is extracted
from the ore and transported in the form of sulphate, I arrange in a separate
building the reservoirs C, C, in which the metallic zinc, produced by the reduction
of the sulphates by means of electricity, is collected. These reservoirs consist of
wooden vats lined with lead, or of glass, stoneware, or brickwork or masonry
lined with bitumen, or' of any other material capable of resisting the corrosive
action of sulphuric acid. In these reservoirs are placed a series of thin sheets or
plates b, b, of zinc, which serve as cathodes upon which the zinc is precipitated;
the surface of these sheets must be proportioned to the electric power employed.
The cathodes may be formed of copper or polished brass from which the zinc
deposit may be readily removed. In front of each cathode I place an anode c of
carbon; platinum, lead, or of other material which is a conductor of electricity,
and naturally insoluble in sulphuric acid or coated so as to be insoluble therein.
In the production of zinc by my process any arrangements may be used which
are utilized for depositing other metals by means of electricity.
The solution of sulphate of zinc is conducted by dip-pipes d, d, to the bottom of
the said precipitating reservoirs C, C, in a regular manner and in determined
quantities. The zinc which is precipitated in a metallic state upon the cathodes
by the decomposition of the sulphate sets free a proportionate quantity of sulphuric
acid which passes to the upper part of the bath above the sulphate which is of
greater density.
.
The-liquid-at-the-upper-part-of-the-bath,-which-becomes-continually acid, flows
away through the openings o, o, in proportion as sulphate is introduced at the
bottom of the reservoir. This sulphate is designed to replace it'in restoring zinc
to the bath in the same degree as it is abstracted therefrom by precipitation.
By means of this continuous stream the sulphate bath is maintained at the
most suitable degree of concentration and acidity, and the production of zinc is
regular.
The acid liquid which is exhausted from the upper part of the bath is allowed
to pass directly to the heaps of ore, or preferably into a special reservoir where
the degree of its acidity can be controlled at all times.
The reservoirs C, C, may be placed on a level lower than that of the reservoir B,
and the acid from the said reservoirs C, C, may be raised by a pump P to the
reservoir R, or the reservoirs C, C, may be arranged above the reservoir B, in
which case the acid will flow by gravity into the said reservoir R.
In cases where blende is specially designed to be treated, and the treatment
produces a quantity of acid which the ore is incapable of absorbing, the excess of
acid is taken from this reservoir to be used in any manufacture, or is reduced
to a condition suitable for commercial purposes by the ordinary well known
processes.
In some cases, and more especially when very pure calamine is to be treated, or
in the treatment of oxides of zine arising from the fusion of metal, the above
described arrangements may be simplified. In this case the ore or the zinc-ash is

page_text: dissolved in the same reservoir in which the zinc is precipitated by the action of
the electric current. For this purpose the plant comprises in addition to the motor
engine and the electric machine only one series of receivers coupled together, and
designed to receive, one, the anode surrounded by the material to be attacked, and
the other the cathode, upon which the zinc is to be precipitated. The one of the
recipients contained within the other should be made of porous material, such as
porcelain, stone, terra-cotta, or woven fabric, so as to prevent the deposited zinc
becoming soiled or stained by the ore.
Or I may use long vessels or reservoirs divided in the interior by a series of
porous partitions, between which are placed alternately the anodes surrounded by
ore and the cathodes, upon which the zinc is deposited.
The apparatus thus constructed is connected with the electric machine by
conducting wires in the manner practised in plating metals.
In all cases the surfaces of the anodes and cathodes must be increased sufficiently
to exhaust the power or intensity of the electric current, so as to obtain therefrom
the maximum production, and the porous partitions or vessels should be removable,
so as to facilitate the periodical cleaning out of the residues which accumulate.
The ore or the oxide of zinc, which are bad conductors of electricity, are mixed
with a small quantity of carbon, which being a good conductor of electricity
connects the anode with the whole mass and facilitates its dissolution.
If zinc-ash or skimmings or residues of the fusion of zine are to be treated, the
quantity of metal contained therein will form a soluble anode, and contribute to
the increase of the deposit of zinc upon the cathode.
A "Gramme " or any other machine for generating electricity by means of
motive power transmits electricity by conducting wires into the special building
wherein the precipitating reservoirs are situated. The machine for producing the
electricity is set in motion when required by a steam-engine, or preferably by a
fall of water, which is frequently found in proximity to mines.
The said process is characterized by the following features, viz. :-The employ-
ment of electricity for treating zinc ores, the production of electricity for this
purpose by a prime mover, the treatment by the wet process of zinc ores for
manufacturing purposes, the extraction of the sulphuric acid required for its
dissolution from the ore itself, the utilization of all the useful materials contained
in the ore, and the production of pure zinc.
The advantages my process offers when compared with the usual process of
distilling are as follow, namely:-The roasting of the blende at a very low tempe-
rature for producing sulphates is much less costly than that heretofore practised,
in which great heat must be applied for decomposing the sulphates, the formation
of which cannot be avoided. In the very rare cases in which a steam-engine will
have to be used a quantity of coal is required for each one hundred kilogrammes
of zinc produced, which is almost equal to that required in distillation for each one
hundred kilogrammes of ore, but the cost of coal is nil when a hydraulic motor is
available, the consumption of refractory material in comparison to that in the
distilling process is almost nil, the manual labour is of much less importance and
is less difficult, and consequently less expensive, the deficit in the quantity of zinc
obtained is reduced, the lead, silver, and all useful materials contained in the ore.
are collected, an excess of acid is produced which can be utilized, and the treatment
of the ore at the mines produces considerable economy with respect to transport.
I can, by treating them at the mines, utilize poor ores which cannot bear the
heavy expense for transport and treatment by the dry process, and the zinc
produced is purer than that obtained by distillation; it is consequently of greater
value.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,-
First. The transformation or conversion of zinciferous materials into soluble
sulphate or sulphite by means of the sulphur contained in blendes.

page_text: Second. The reduction in a manner useful for industrial or manufacturing
purposes of sulphates or sulphites of zine by means of electricity developed from
mechanical force or energy, substantially as above described.
In witness whereof, I, the said Henry Harris Lake, have hereunto set my
hand and seal, this Twenty first day of January, in the year of our Lord
One thousand eight hundred and eighty two.
HENRY H. LAKE.
(L.S.)