IMPROVED PROCESSES AND APPARATUS. FOR THE TREATMENT OF ORES
Year: 1885

page_text: I, CUMMINGS CHERRY, of Chicago, Illinois, United States of America, Geologist,
Mineralogist and Chemist, do hereby declare the nature of my invention for
IMPROVED PROCESSES AND APPARATUS. FOR THE TREATMENT OF ORES to be as
follows:-
My invention relates to improvements in the processes and apparatus described
in the specification of former Letters Patent dated 18th December A D. 1883
N° 5788 and more particularly to the roasting or calcining of the ores and to the:
treatment thereof by heated air and superheated steam.
The object of my present invention is to thoroughly purify ores by removing
or separating therefrom the sulphur, arsenic, phosphorus, antimony, and other
metalloids or impurities which may be combined with the said ores in their
natural state. I accomplish this result by treating the ores as hereinafter set forth
and thus forming chemical combinations and carrying off or expelling the same
from the ores. Moreover, when desired, I save the gaseous or volatile products by
condensation in suitable cooling vessels or chambers. This condensation is
effected when the different fusing or vaporizing points of the respective metalloids
are attained but the temperature is at all times kept below the fusing point of the
metal in the ores, thus precluding any possible waste or loss of such metal.
Heretofore ores have been more or less purified by roasting then in heaps in the
open air or in kilns or ovens; also by heated air in furnaces; and by superheated
steam, as in Rivot's process. There have also been various combinations of these
processes. But the treatment by heated air and superheated steam in distinct and ;
continuous sub-processes, one following the other has not heretofore been known.
Various methods have been heretofore adopted for purifying ores in the process
of fusion or reduction. The most noted of these are the "Bessemer" and the
"Thomas-Gilchrist" processes. But all of these methods have failed or have met
with partial success at great expense, by reason of the loss of the metal, and
without the essential quality of uniformity of the product. By my process every
particle of ore receives necessarily the same treatment as every other part of the
charge, and, when the process is correctly carried on, the result is uniform to a
remarkable degree. The most refractory ores are made easy of reduction without‍
DJI

page_text: and cause a continuous current through the same and a continuous escape or the
vapors evolved. This treatment is continued for from one to three hours, or until
the gases of the steam have formed chemical combinations with any sulphur,
phosphorus, arsenic, or other metalloids that may have been combined with the
ores and such chemical combinations have been carried off or expelled through the
escape pipe in the form of vapors, such as sulphuretted bydrogen, phosphuretted
hydrogen, phosphine, antimonial and arsenical vapors, and occluded oxygen and
the like, and the ores have been deoxidized. This condition may readily be ascer-
tained from the odour of the escaping vapors.
When it is desired to save the bye-products, the escape pipe is terminated in
condensing chambers or cooling vessels. This sub-process is theu prolonged in
steps or stages carefully regulated with respect to temperature to the vaporizing
points of the different combined metalloids; commencing with the metalloid
having the lowest point of fusion or vaporization and increasing in temperature in
steps or stages to that of the highest point of fusion or vaporization, thus
vaporizing and carrying off and condensing the sulphur, arsenic and other
metalloids separately.
3rd SUB-PROCESS.
2
The steam is now shut off and heated air is again forced through the ores in the
retort at a temperature of from 300 to 750 degrees Fahrenheit and under a
pressure within the retort of not less than 5 pounds per square inch and passing
out through the escape pipe in a continuous current for from one to three hours.
This additional treatment with heated air is for the purpose of oxidizing and
carrying off any portion or trace of the metalloids which may remain in an
amorphous condition or otherwise, such as the red oxide of phosphorus and the
like, and also to nitrogenize the ores and thoroughly reoxidize such as are capable
of reoxidation if desirable.
:
With some classes of ores, and where the principal object is to extract and save
the metalloids, and presumably where ores are to be used for other purposes than
reduction, treatment by the first and second sub-processes only is required.

page_text: Improved Processes and Apparatus for the Treatment of Ores.
I, CUMMINGS CHERRY, of Chicago, Illinois, United States of America, Geologist,
Mineralogist and Chemist, do hereby declare the nature of my invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to improvements in the processes and apparatus described
in the specification of former Letters Patent, dated 18th. December, A.D. 1883,
N° 5788.
The chief object of my present invention is to provide, in a more efficient manner
than heretofore, for thoroughly purifying the ores, to prepare them for smelting,
amalgamation or other treatment, by removing or separating therefrom the
sulphur, arsenic, phosphorus, antimony, or other metalloids, acid salts, and other
impurities capable of volatilization which may be combined with, or present in, the
said ores in their natural state. Metalloids" may generally be recognized by the
following characteristics:-They are gaseous or capable of vaporization, have no
metallic lustre, are bad conductors of electricity, have a relatively low density, and
their oxides, on combining with water, ordinarily produce acids. In addition to
the above impurities, when metals other than the ultimate metal or metals to be
obtained by my process are present in the ore, I may volatilize the same at their
respective temperatures of vaporization up to, and not exceeding, 1200 degrees
Fahrenheit.
According to my present invention, I effect the purification of the ores and
prepare the same for smelting, amalgamation or other treatment by subjecting
them to the action of currents of heated air under pressuro and superheated steam
under pressure in a closed retort or other vessel as hereinafter set forth, with the
effect that the said impurities are carried off and expelled from the ores.
My present process is carried on without the application of external fire to the
retort for the purposes described in my specification of Letters Patent No 5788,
A.D. 1883, and, in this respect, differs from the process described in the said former
specification. The temperature within the retort, therefore, depends upon that of
the heated air or steam admitted thereto, and is consequently more easily controlled
than when the retort is heated externally. In some cases, however, if desirable,
the waste heat or gases from the retort inay be applied externally to the retort
for the purpose of preventing the radiation of heat therefrom and for assisting to
maintain the desired temperatures.
Moreover, according to my present invention, I so regulate the temperature that
it is gradually raised to the different points of vaporization of the various
metalloids, or other substances capable of volatilization below the temperature
above mentioned, contained in the ores, or to the various degrees of temperature at
which the hydrogen of the steam will combine with the said metalloids or other
volatile impurities.

page_text: Each metalloid or substance may be thus, generally speaking, in its turn,
vaporized and carried off separately or nearly so. Thus the formation of chemical
combinations which would injuriously affect the quality of the ultimate product of
my process, is, in many cases, avoided.
When desired, I save or recover the gaseous or volatile products by condensation
in suitable vessels or chambers. By careful regulation of the temperature, as
above described, I am enabled to accomplish this result in a very advantageous
manner.
In dealing with the above-mentioned volatile or gaseous products, I find it
advisable, in some instances, to introduce the same into vessels, or other apparatus
usual in such operations, containing chemicals in solution which retain the said
volatile or gaseous products in chemical combination. In other instances, I pass
the said volatile or gaseous products over trays containing chemicals capable of
retaining or absorbing the same. By this method, in the treatment of iron or
other ores containing phosphorus, I may obtain phosphate of lime or other
alkaline earth by causing the volatile phosphorus or phosphoretted hydrogen to
combine with lime or other alkaline earth or to replace an equivalent in some
chemical combination of the same.
:
In most of the processes heretofore, adopted for the purification of ores, there is a
loss of metal and a want of uniformity of the product; but, in my process, the
temperature can, at all times, be very easily kept below the fusing point of such
metals in the ores as are not intended to be vaporized, thus precluding waste or
loss of such metals. Moreover, by my process, uniformity or homogeneity of the
product is ensured.
In the accompanying drawing, I have shewn, in vertical central section, an
apparatus for carrying on my process, but other suitable apparatus may be used.
A is a retort or purifier, which has a boiler-plate casing a provided with two
linings b, c. The inner lining c is of fire-brick and is about nine inches thick. The
outer lining b is about two inches thick, and is composed of asbestos or of cinders
or the like or of any other suitable material which will permit the expansion and
contraction of the fire-brick lining without affecting the casing a.
B, C, are plates at the upper and lower ends of the retort; these plates are made
with flanges B, C, which project into, and are rivetted to, the cusing a.
C' is a
cast metal tube or annular piece secured by bolts Cs to the plate C, so that it can
be detached therefrom when necessary. D, E are caps or covers for closing the
upper and lower ends of the retort. These caps or covers are secured respectively
to the plate B and tube C by bolts D¹, E¹.
F is an escape-pipe secured to the top plate B and connected with the interior of
the retort by a passage F1 through the lining c. This pipe is provided with a
pyrometer d and a pressure-gauge e, whereby the temperature and pressure in the
top of the retort may be ascertained at any time. The escape-pipe F is also
provided with a valve f for regulating the escape of the vapors from the retort and
for controlling the temperature and pressure within the same as required.
The tube C has a circular pipe or cavity g formed therein, which pipe com-
municates with the inlet-pipe h and has holes, as at g³, whereby an action is
produced similar to that of a series of tuyeres. These holes may be situated at
any suitable intervals around the tube C³ and may be of any desired diameter.
They admit the steam or air into the retort so that it will ascend uniformly
through the ore. If desired, the said retort is provided, for this purpose, with
tuyeres like an ordinary blast-furnace.
The inlet-pipe h is provided with a pyrometer i and a pressure-gauge k, whereby
the temperature and. pressure of the steam or air as it enters the retort may be
ascertained at any time. The joints are all made gas-tight.
When it is desired to save the bye-products, the escape-pipe F is conducted
into vessels or chambers containing chemicals as herein before mentioned. Such

page_text: apparatus being well known in gas-works and chemical manufactories, I do not
consider it necessary to describe, or furnish drawings of, the same.
My process is divided into the following three sub-processes, viz :—
1st SUB-PROCESS.
The ores to be treated are broken or crushed into particles of suitable size,
preferably of the size of hazel-nuts, and are put into the retort. Whenever the
fluxes to be used in sub: equent reduction of the ores contain any impurities of the
nature herein before mentioned, I put the same into the retort and treat and purify
the same simultaneously with the said ores.
The caps D, E at the top and bottom of the retort being securely fastened, air is
forced by an air-compressor through a heater or hot-blast stove and through the
inlet pipe into the retort A at temperatures as required of from 212 to 1200 degrees
Fahrenheit, and under a pressure of say from 5 to 25 pounds per square inch. The
ores are thus gradually heated until the temperature in the top of the retort
reaches any required elevation not exceeding 1200 degrees Fahrenheit, the valve f
of the escape-pipe and the superheating being so adjusted as to maintain the desired
pressure and temperature within the retort. Heated air is forced in this manner
into the retort in a sufficient quantity to cause a continuous current thereof to pass
through the ore in the said retort, under the desired pressure and temperature, for
from one to three hours, or until all the acids, salts and part of the occluded
oxygen of the ores are broken up or separated, and the ores are thoroughly
disintegrated. By this sub-process, the water of constitution and the water of
crystallization, combined with the various gases which may be given off at this
stage of the process, are expelled from the ores, together with part of the sulphur,
phosphorus and other impurities capable of vaporization. The ores are thus
rendered porous or spongy and are brought into the most favorable condition to be
acted upon by superheated steam as hereinafter described in the sub-process next
mentioned.
The air is now shut off and the ores in the retort are maintained at a temperature
not exceeding 1200 degrees Fahrenheit, but care must be taken to preserve such a
temperature as will prevent the oxygen uniting with the ores in the retort to form
metallic oxides of the said ores. This is best effected by admitting the steam
immediately on the termination of the first sub-process. If, by the cooling of the
said ores, metallic oxides have been formed, the heated air must be again introduced,
as described in the first sub-process, and then superheated steam again admitted.
The superheated steam is forced through the inlet-pipe h and through the ores in
the retort under a pressure, within the retort, of not less than 5 pounds per square
inch, but preferably of from 40 to 100 pounds per square inch. The supply and
superbeating of the steam are regulated and the valve f of the escape-pipe adjusted
in such a manner as to maintain the desired pressure and temperature within the
retort, and cause a continuous current of steam to pass through the ores.
The
superheating of the steam is, moreover, so regulated that the temperature within
the retort will be raised by successive steps or stages to the different degrees of
temperature at which the hydrogen of the steam will combine with the metalloids
or other volatile impurities contained in the ores, thus substantially eliminating
each metalloid (save as hereinafter mentioned) or other volatile impurity in its
turn, commencing with that having the lowest point of vaporization and ter-
minating with that having the highest point of vaporization. This treatment is
continued for from one to three hours, or until the hydrogen of the steam has
formed chemical combinations with the remaining sulphur, phosphorus, arsenic or
other metalloids that may have been combined with the ores, and such chemical
con binations have been carried off or expelled through the escape-pipe in the form

page_text: The regulation of the temperature within the retort in the manner above
described is an important feature of my present invention, as I am thus enabled
to avoid the formation of many chemical combinations in the retort which would
be adverse to the complete purification of the ores.
3rd SUB-PROCESS.
The steam is now shut off, and cold or heated air is then forced through the ores
in the retort under a pressure, within the retort, of not less than 5 pounds per
square inch. The cold or heated air is thus introduced into the retort in a sufficient
quantity to cause a continuous current thereof to pass through the ores for from
one to three hours.
This additional treatment with cold or heated air is for the purpose of oxidizing
and carrying off any portion or trace of the metalloids which may remain in the
retort in an amorphous condition or otherwise, such as the red oxide of phosphorus,
or amorphous phosphorus, and the like, which readily combine with the oxygen
and take fire spontaneously, and also to nitrogenize the ores and thoroughly
re-oxidize such as are capable of re-oxidation, if desirable.
With some classes of ores, and also where the principal object is to extract and
save the metalloids, and, in some cases, where ores are to be used for other
purposes than reduction, treatment by the first and second sub-processes only.is
required.
The third sub-process may be applied to ores which have previously been subjected
to treatment by processes having the same or similar objects as those described in
the second sub-process above mentioned.
During the whole of the process and sub-processes, the temperature must not be
permitted to attain the fusing point of the metals in the ores subjected to treatment,
except in cases where a metal of low fusible point exists as an impurity which
requires elimination as herein before stated.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I wish it understood
that I do not claim broadly or irrespectively of my improvements as above set
forth, the treatment of ores in a closed vessel or retort by means of either heated
air or superheated steam as 1 am aware that various processes for this purpose
have been described in which heated air or superheated steam are used either alone
or mixed with other vapours or gases, nor do I claim the employment of heated
air and superheated steam in consecutive sub-processes when such sub-processes
are carried on in a closed retort, muffle or oven, to which external fire is applied,
as, for example, in the manner described in my specification N° 5788, A.D. 1883,
and into which a current of beated air in the first sub-process is not admitted, but
what I claim is :-
First. The above described process of purifying ores, or fluxes or both, consisting
in subjecting them, under pressure in a closed vessel or retort, without the application
to the vessel or retort of external fire, first to the action of heated air, secondly
to the action of superheated steam, the temperature of which is so regulated that
the metalloids or other impurities will be separately and successively vaporized and

page_text: expelled from the ores, and thirdly to the action of cold or heated air, substantially
as, and for the purposes, described.
Second. The above described process consisting in subjecting oras or fluxes, or
both; under pressure in a closed vessel or retort, without the application to the
vessel or retort of external fire, first to the action of heated air and then to
the action of superheated steam as above described, for the purpose of purifying
the ores or fluxes, or both, or for the purpose of recovering bye-products therefrom
by the condensation or absorption of the vapors evolved, substantially as herein-
before described.
Third. The treatment by the 3rd sub-process, substantially as, and for the
purposes, herein before described, of ores or fluxes, or both, which have been
previously subjected to the action of steam.or hydrogen.
Dated this 12th dow of Art 1006
HASELTINE, LAKE & Co.,
Agents for the Applicant.