IMPROVE MENTS IN THE TREATMENT OF ORES AND OTHER SUBSTANCES CONTAINING METALS, TO OBTAIN PRODUCTS THEREFROM, AND THE APPARATUS USED THEREIN."
Year: 1853

page_text: David Zemmer, of the boroug
County
Newcastle-upon-Tyne, Chemist, for the Invention of "IMPROVE
MENTS IN THE TREATMENT OF ORES AND OTHER SUBSTANCES CONTAINING
METALS, TO OBTAIN PRODUCTS THEREFROM, AND THE APPARATUS USED
THEREIN."
MENTS IN THE TREATMENT OF ORES AND OTHER SUBSTANCES CONTAINING
METALS, TO OBTAIN PRODUCTS THEREFROM, AND THE APPARATUS USED
THEREIN."
Sealed the 7th June 1853, and dated.the 14th April 1853.
PROVISIONAL SPECIFICATION left by the said David Zenner at
the Office of the Commissioners of Patents, with his Petition, on
the 14th April 1853.
I, DAVID ZENNER, of the Borough and County of Newcastle upon
5 Tyne, Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE TREATMENT OF ORES AND OTHER SUBSTANCES CON-
TAINING METALS, TO OBTAIN PRODUCTS THEREFROM, AND THE APPARATUS USED
THEREIN," to be as follows:-
The first part of my improvements refers to ores which contain iron,
combined with sulphur or arsenic, or both together, generally called
pyritical ores, which may sometimes contain small quantities of gold,

page_text: silver, copper, cobalt, nickel, and bismuth, besides the usual earthy or
carbonaceous matters, and the apparatus used in their treatment.
Firstly, my Invention consists in the use of a vertical retort, which is
heated by means of flues circulating round the outside of it. The ores
to be heated are introduced at the top, and gradually moving down-
wards are (when sufficiently heated) discharged by an opening or door
near the bottom of the retort. By this operation the ores are freed
from a portion of their volatile matters without coming in contact with
atmospheric, air, and leave, a, combination of iron and other metals
with sulphur, called sulphurets or sulphides, mixed with earthy or car-
bonaceous matters. When the substances to be treated do not contain
sufficient sulphur, it is supplied by any means capable of rendering it.
The volatile fumes of arsenic or sulphur are condensed and collected as
usual.
Secondly, I use the heated ore for the production of salts of
iron and the concentration of the precious or valuable metals which
may be contained in the ore. For this purpose I dissolve the heated
ore in a close vessel with diluted sulphuric or any other acid (with or
without the application of heat), which dissolve the sulphuret of iron
by preference first; and when the quantity of acid has been properly
calculated, so as to be rather less than necessary to dissolve all the sul-
phuret of iron, it will leave the other substances undissolved. When
an excess of acid has been applied, some of the valuable metals may be
dissolved, which I obtain from the solution by adding some sulphuret of
irou (either in the dry or in the hydrated state) or some substance con-
taining sulphuret of iron, which precipitates the valuable substances out
of the solution; or sulphuret of iron may be produced by precipitating
a part of the solution itself with the sulphurets of an alkali, or an alka-
line earth. The solutions containing the iron in combination with the
acid used are either crystallized or otherwise made use of: The con-
centrated residues or precipitates are removed and treated further,
according to known methods, whether they contain one or more of
valuable substances.
The sulphuretted hydrogen- gas which is disengaged is conducted
into a proper apparatus for converting it into sulphuric acid by the
usual means..

page_text: The second part of my Invention refers to the separation of valuable
metals out of solutions which are not obtained by dissolving sulphuretted
substances, as above described.
When the ores or other substances are in a metallic state, or are
naturally oxygenized, or whether they have been roasted and have then
dissolved in an acid, I pass a stream of sulphuretted hydrogen through
the solution, and then put a quantity of sulphuret of iron proportionate
to the valuable metals which are to be precipitated. Or another modi-
fication is, that I precipitate the solution of the ore partly or entirely
with the sulphide of an alkali or an alkaline earth, and after some
time the precipitate will contain all the valuable metals, beside a part or
all of the iron contained in the solution. This sulphuretted precipitate
is treated, as above described, with diluted acids.
The third part of my Invention consists in the employment of proto-
sulphuret of iron, or any substance containing it, instead of the metallic
iron hitherto used in the manufacture of copperas. To reduce the
tersulphate of peroxide of iron (or what is called the free acid) con-**
tained in the solutions or liquors obtained from the pyrites beds, or
obtained by dissolving slags, or other substances containing iron in
sulphuric acid, for the purpose of making copperas.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said David Zenner, in the Great Seal Patent Office,
on the 13th October 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME,
DAVID ZENNER, of the Borough and County of Newcastle upon Tyne,
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of April, in the year
of our Lord One thousand eight hundred and fifty-three, in the six-
teenth year of Her reign, did; for Herself, Her heirs and successors,
give and grant unto me, the said David Zenner, Her special licence

page_text: that I, the said David Zenner, my executors, administrators, and
assigns, or such others as I, the said David Zenner, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the, term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN THE TREATMENT OF ORES AND OTHER SUBSTANCES CONTAINING METAIS,
TO OBTAIN PRODUCTS THEREFROM, AND THE APPARATUS USED THEREIN," upon
the condition (amongst others) that I, the said David Zenner, by
an instrument in writing under my hand and seal, should particu-
larly describe and ascertain the nature of the said Invention, and in
what manner the same was to be performed, and cause the same to be
filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said David Zenner, do hereby de-
clare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by
the following statement thereof (that is to say):
The first part of my improvements refers to ores which contain iron,
combined with sulphur or arsenic, or both together, generally called
pyritical ores, which may sometimes contain small quantities of gold,
silver, copper, cobalt, nickel, and bismuth, besides the usual earthy or
carbonaceous matters, and the apparatus used in their treatment.
Firstly, my Invention consists in the use of a vertical retort, which is
heated by means of flues circulating round the outside of it. The ores
to be heated are introduced at the top, and gradually moving down-
wards are, when sufficiently heated, discharged through an opening or
door near the bottom of the retort. By this operation the ores are
freed from a portion of their volatile matters without coming in contact
with atmospheric air, and leave a combination of iron and the other
valuable metals with sulphur, called sulphurets or sulphides, mixed
with earthy or carbonaceous matters. When the substances to be
treated do not contain sufficient sulphur it is supplied by means capable
of rendering it. The volatile fumes of arsenic or sulphur are. condensed

page_text: and collected as usual. This furnace is also applicable to other
chemical or metallurgical operations.
Secondly, my Invention consists in the production of salts of iron
from the heated ore, and concentration of precious or valuable metal
which may be contained in the ore. For this purpose I dissolve the
heated ore in a close vessel, with diluted sulphuric acid or any other
acid (with or without the application of heat), which dissolve the
sulphuret of iron by preference first; and when the quantity of acid has
been properly calculated, so as to be rather less than necessary to
dissolve all the sulphuret of iron, it will leave the other substances
undissolved. When an excess of acid has been applied, some of the
valuable metals may be dissolved, which I obtain from the solution by
adding some sulphurét of iron, either in the dry or in the hydrated state,
or some substances containing sulphuret of iron, which precipitate the.
valuable metals out of the solution; or sulphuret of iron may be pro-
duced by precipitating a part of the solution itself with the sulphurets
of an alkali or an alkaline earth. The solutions containing the iron, in
combination with the acid used, are either crystallized or otherwise
made use of. The concentrated residues or precipitates are removed
and treated further according to known methods, whether they contain
one or more of the valuable substances mentioned. The sulphureted
hydrogen gas which is disengaged is conducted into a proper apparatus
for converting it into sulphuric acid by the usual means.
The third part of my Invention refers to the separation of valuable
metals out of solutions which are not obtained by dissolving sulphureted
ores, as above described. When the substance has been roasted or is
naturally oxygenized, or when it contains no oxygen, and has been
dissolved in an acid, I pass through the solution a stream of sulphureted
hydrogen gas, and then I put into the solution a quantity of sulphuret
of iron proportionate to the valuable metals which are to be precipitated.
Or another method is that I precipitate the solution of the ore, partly or
entirely with the sulphide of an alkali or an alkaline earth, and after
some time, the precipitate will contain all the valuable metals, besides
part or all the iron contained in the solution. This sulphureted pre-
cipitate is treated, as above described, with diluted acids.

page_text: The fourth part of my Invention consists in the employment of
proto sulphuret of iron, or any substance containing it, instead of the
metallic iron hitherto used, to reduce the tersulphate of peroxide of iron,
or to saturate what is called the free acid contained in the solutions or
liquors obtained from the pyrites beds, or obtained by dissolving slags or 5
other substances containing iron in sulphuric acid, for the purpose of
Figure 2, is a vertical
Figures 4, and 5, are
.Figure 1, is a front elevation of the furnace.
section. Figure 3, is a transverse section.
horizontal sections from 4, to 4, and from 5, to 5. Figure 6, shewing
half of the outside of retort, with the arch above the fireplace, from
whence the spiral flues begin. The same letters indicate similar parts
in each of these figures.
. a, a, is the retort, being either of circular, oval, or polygnol basis,
and with conical or pyramidical ascending sides or walls, or partly
conical or pyramidical. It may be made of any suitable material, but
I prefer fireclay. B, B, are the narrow spirally ascending flues, for
conducting the flame and heated gases one or more times around the
outside of the retort to heat it, and escaping by C, C, into the chimney
or flue. A', A', is the door or slider, closing the top of retort, which
moves in a close case to prevent the escape of noxious vapours. E, E,
is the pipe for conducting the volatile matters (which may be separated)
to the condensing chamber or flues. This pipe may be at any other
point of the retort, or there may be more than one such pipe. F, F,
is the discharge door by which the heated substances are withdrawn.
Figure 7, is a longitudinal section, and Figure 8, is a transverse
section of decomposing vessel. These vessels may be constructed of
any suitable material, and may or may not be lined with lead, and may
be provided with a perforated false bottom.
The scale of these drawings is half an inch to the foot.
I use this furnace (Figures 1, to 6, inclusive) as follows:-After it has
been first brought slowly to a bright red heat, the discharge door. F,
being closed, the retort is charged quite full, by means of the hopper

page_text: and the slider A', with the inatters or ores to be heated, and-the top of
retort is then closed, and another charge put into the hopper, which is
then also covered. The charge is then exposed for a space of two or
more hours, according to the nature of the ores, to a bright red heat, by
which they are deprived of their volatile matters, such as sulphur or
arsenic, which escape by the vapour escape pipe E, into a close chamber,
for being condensed there, as well understood by refiners of sulphur or
arsenic. When the ores under treatment are bisulphurets of iron, I
prefer having two or more vapour pipes communicating with the con-
densing chamber; but when the ores are arsenical pyrites, such as are
known by the name of mispikel, which contain sulphur or arsenic in
combination with the iron and other metals, I prefer having only one
vapour escape pipe at the lower part of the retort: this arrangement
forces all fumés set free, even in the higher parts of the retort, to pass.
through the lower and hotter part of it, by which they are more perfectly
decomposed into arsenic, which escapes, and sulphureted metals, whicli
remain in the retort. When the ores to be treated consist of arsenical
pyrites containing no sulphur, or a lesser quantity than required to
leave the metals in the state of proto sulphurets, I mix with it a
quantity of bisulpliuret of iron, or any other substance capable of
rendering sulphur, sufficient to leave all the metals in combination
with sulphur, and thereby rendering the arsenic free to escape.
proper quantity in such cases must be found by trials. When the time
for discharging has arrived, the sliding doors of the fume case are suffi-
ciently opened to introduce a rake or stirring tool, and then the dis-
charge door F, is raised by means of its chain and pulley, and the
heated ore is easily withdrawn. A discharge may average from one-
sixth to one-third of the whole contents of the retort, and must stop as
soon as the pieces of ore shew themselves in the discharge opening not
of a bright red heat; the discharge door is then closed and well fastened;
the slider A', is then withdrawn, and the charge already in the hopper is
thereby dropped into the retort; the slider is then replaced, and the
hopper immediately filled, as before. After some time, which must be
ascertained by experience, another portion of heated ore is withdrawn
and the operations above described repeated.
The

page_text: .
The ore withdrawn from the retort may be allowed to fall into a
water trough supplied with a constant stream of cold water; by this
means the worknien are less exposed to noxious vapours, and the
ore is also made brittle, and more suitable for future operations. The
.ore is raked from the trough when sufficiently cool.
It is understood that the quantity of a charge may vary according to
the size of the retort or other arrangements made; or rather according
to the quantity of heated ore withdrawn. It is well to keep the retort
always full, or nearly so, but not to put so much into it so as to prevent
the closing of the slider A'.
The second part of my Invention refers to the decomposing of the
heated ores and substances which contain proto sulphuret of iron,
whether they are produced by means of the furnace just described, or
by any other means, such as a blast furnace, as used by Mr. Isaac Bell
in his patent process for the recovery of sulphur from alkali waste, or
any other furnace.
I prefer to conduct the decomposition as follows:-I fill the decom-
posing vessel, Figures 7, and 8, about three-quarters full with the heated
matters, by spreading it on the false bottom B, B; and after closing the
manhole A, air-tight, I allow diluted sulphuric acid of not exceeding
1.24 specific gravity to run in till nearly full; but so as to allow room
for ebullition and the escape of gases. At the same time with the acid,
high pressure steam is turned into the decomposing vessel, by means of
the steam pipe D, D, for the purpose of heating and agitating the con-
tents, which I continue to boil until the evolution of sulphureted
hydrogen ceases. When the ores contain other valuable metals, such
as cobalt or nickel, the boiling is continued until the solution no longer
contains either of these metals dissolved, which may be ascertained by
the usual chemical tests.
When the evolution of sulphureted hydrogen gas has ceased, the
steam is turned off, and the contents of the vessel are allowed to settle,
and the liquor is then drawn off through the tap, or by a syphon, or by
any other means, into coolers, for crystallization, as understood by
copperas makers. I now run into the vessel another quantity of
diluted sulphuric acid, and proceed the same as just described; and

page_text: repeat the operation thus one or more times, until the ore is entirely
exhausted. The last boiling may contain considerable quantities of free
or uncombined acid, and in this case may be run on a new quantity of
ore, and boiled with it until it is fully saturated; but when the quantity
of free acid is only small, it will be found preferable to run it at once
into the crystallising vessel, and return only the mother liquor after
crystallisation.
When the ores under treatment contain other valuable metals which
could be dissolved by the acid used, the solution ought to be tested,
before drawing it off, by the usual chemical tests, and the liquor must
be boiled for some time longer when any other valuable metal has got
dissolved.
When the proto sulphuret of iron has been all exhausted, a con-
tinued boiling, with an excess of acid, is very liable to dissolve a part
of some of the valuable metals, and in this case a small quantity of
ore, containing proto sulphuret of iron, must be added, and again
boiled, to saturate all the acid, and precipitate all the valuable metals
which may have become dissolved. But I find it always preferable to
regulate the quantity of acid so as to leave a small quantity of sulphuret
of iron undissolved in the residue with the valuable metals, which is
always the case when, for every part of pure proto sulphuret of iron
in the ore or matter under treatment, not more than three and three
quarter parts of diluted sulphuric acid of 1.22 specific gravity, or three
and one half parts of hydrocholric acid of 1.123 specific gravity, is
used.
When hydrocholric acid is used the liquor need not be crystallized.
The sulphureted hydrogen gas disengaged during these operations is
conducted away by the gas escape pipe, either into a proper burner,
to be burned and converted into sulphuric acid, as well known to
chemists, or may otherwise be made use of.
When the solution or succession of boilings of the solution are
concluded, and before the last boiled liquor is drawn off, I throw into.
the vessel a jet of steam, (Figures 7, and 8, E.) above the level of the
liquor, to drive out all the remaining sulphureted hydrogen gas, which

page_text: would otherwise- inconvenience the workmen when removing the
residues.
When the matters under treatment contain, besides the proto sul-
phuret of iron, no other valuable or precious metals, or their sulphurets,
the residues, consisting of the usual carthy or carbonaceous matters,
must be removed from the decomposing vessels, after being washed with
water from the solution adherent to it. But when the matters or ores
do contain any other valuable metals in combination with the sulphur,
beside the remaining iron, such as gold; silver, copper, and bismuth,
either any one of these substances alone or several of them together,
as above mentioned; they may be subjected to a smelting process, or
dissolved from the residue by acids or any other suitable means,
as well known to chemists.
When the residues contain cobalt or nickel, beside the remaining
iron sulphuret or excess which has been added for the purpose of
precipitation, and it is desired to remove the iron from them, I place
this residue in a vessel made of stone, brick, or glazed earthenware,
with sufficient sulphuric acid or hydrocholric acid, and also some nitric
acid, or substances capable of rendering it, or nitric acid alone, and
apply heat until all these metals have been dissolved. Or it may be
preferable to roast an oxide the residues first, by access of atmo-
spheric air, and then dissolve them in a suitable acid; the solution is
then withdrawn from the earthy or other matters left undissolved,
which latter must be well washed with water to remove all the solution
of the valuable metals. These washings are added to the main part of
the solution, which is now precipitated with a previously prepared
solution of a proto sulphuret of an alkaline base, or alkaline earthy
base, such as sulphide of sodium, pottassium, barium, strontitum, or
calcium. When sulphuric acid has been used, I prefer the use of the
sodium sulphuret, but when hydrochloric or nitric acid has been used
any of the three other sulphides may be used with advantage, as
thereby salts of the respective basis are formed, namely, hydrochlorate
or nitrate of baryta, or strontia. The liquor containing the acid used for
the solution of the residues, in combination with the base of the precipi-

page_text: tant and the precipitate in the state of sulphurėts, must be well
agitated, and may also be warmed, and the precipitate is then allowed
to subside, after which the supernatant clear liquor may be either
drawn off or not. I then put into the vessel containing the deposit
cold diluted sulphuric acid of 1.13 specific gravity, or thereabouts, in
excess, and after stirring it often and briskly, during several hours,
it is allowed to subside, and then the clear liquor is drawn off, and the
undissolved portion is well washed with cold water; and it will be found
that the residue contains the valuable metals' mentioned, which are
collected and separated or made further use of, as understood by
chemists, while the solution contains iron only, and may be used for
the manufacture of copperas.
}
When it is required to treat substances which are naturally. oxidized,
such as gossans or oxides of iron or slags, or roasted ores or substances
which contain no oxygen, such as alloys or matts, but other of the
valuable metals above mentioned, either for the manufacture of proto-
salts of iron, or the separation of the other valuable substances, or both
purposes together, and such substances have been dissolved in a suit-
able acid, I introduce into it a quantity of sulphuret of iron, or any
substance containing it, proportionate to the quantity of the metals to
be precipitated, and boil for some time, until all the peroxide of iron in
solution has been reduced to the state of proto salt of the acid contained
in it; or the solutions of nonsulphurised ores or matters may be pre-
pared by dissolving, together with them, a quantity of sulphuret of iron,
or any substance containing it. When all the valuable metals have been
precipated, and will be found with the excess of the sulphureted pre-
cipitant from which it is separated, as above described, by the treatment
of the residues derived from the solution of sulphureted ores. But as
this method of separation involves a great number of successive opera-
tions, I prefer, for solutions obtained from nonsulphurised ores or
matters, the following method:-I first introduce into the solution
a stream of sulphureted hydrogen gas, by which gold, silver, copper,
and bismuth are precipitated, when contained therein. I then intro-
duce into the liquor a quantity of hydrated sulphuret of iron (the

page_text: preparation of which is well known to chemists) or a quantity or part
of the solution may be precipitated by the sulphuret of an alkaline, or
alkaline earthy base, and digest or even heat to boiling during some
lours, during which I often agitate, by which the cobalt and nickel are pre-
cipitated as sulphurets, and a corresponding quantity of the sulphuret
of iron is dissolved. The supernatant liquor may be drawn off or not.
When quite cold, I introduce cold diluted sulphuric acid, of 1 13 spe-
cific gravity, or thereabouts, or its equivalent of hydrochloric acid, so
that the acid is slightly in excess, for the purpose of dissolving the
hydrated sulphuret of iron which is yet contained in the precipitate.
After some hours the liquor is drawn off, and the precipitate containing
the cobalt or nickel, or both, is well washed, and treated as usual.
The fourth part of my Invention consists in the substitution of proto-
sulphuret of iron, or any substance containing it, whether it be made
in the furnace described above, or in a blast furnace, as under Mr. Isaac
Bell's Patent, for the recovery of sulphur from alkali waste, or by any
other way or means, instead of the metallic iron hitherto used in the
manufacture of copperas to reduce the tersulphate of peroxide of iron,
or to saturate what is called the free acid contained in the solutions or
liquors obtained from the pyrites beds; or the liquors obtained by dis-
solving slags or other substances containing iron in sulphuric acid, for
the purpose of making green copperas. "The protosulphuret of iron to
be used in the same manner as the metallic iron.
Having thus described the nature of my Invention, and the manner
in which the same is performed, I would have it understood that I do
not confine myself to the dimensions of the apparatus or other details
herein described, so long as the peculiar character of any part of my
Invention is retained. I am aware that sulphur or arsenic has been
obtained by heating pyritical ores in close vessels or horizontal retorts,
such being done on a small scale only with a great expenditure of fuel,
labour, and vessels, and a comparatively imperfect result, arising from
the low temperature used. But what I claim is,
First, the improvements in retort furnaces by the employment of an
upright retort of conical or pyramidical shape, heated on the outside by

page_text: means of flues, and the application of this retort furnace to metallur-
gical and other chemical operations.
Secondly, I claim the manufacture of green copperas or other salts
of iron by dissolving protosulphuret of iron in diluted sulphuric or any
other acid, as above described.
Thirdly, I claim the concentration and separation of precious or
valuable metals, obtained in or combined with pyritical ores or proto-
sulphuret of iron, as herein described.
Fourthly, I claim the method of precipition and separation of
precious or valuable metals from nonsulphurized ores or matters, and
from solutions by means of protosulphuret of iron, or hydrated proto-
sulphuret of iron.
Fifthly, I claim the use of protosulphuret of iron, instead of metallic
iron, in the manufacture of copperas.
In witness whereof, I, the said David Zenner, have hereunto
set my hand and scal, this Eighth day of October, in the year
of our Lord One thousand eight hundred and fifty-three.
Witness,
ROBERT BLACKETT,
of the Town and County of
Newcastle on Tyne.
DAVID ZENNER. (L.S.)