Improvements in the Manufacture of Manganese and Manganese Alloys Free from Carbon.
Year: 1893

page_text: Date of Application, 3rd Jan., 1893-Accepted, 11th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Manganese and Manganese
Alloys Free from Carbon.
We, WILLIAM HOUSTON GREENE of 204 North 36th Street in the City of
Philadelphia, State of Pennsylvania United States of America Chemist and
WILLIAM HENRY WAHL of 1436 North 13th Street also in the said City of
Philadelphia Chemist do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
The object of our invention is to manufacture on a commercial scale manganese
and manganese alloys which will be wholly free from carbon.
The industrial application of manganese in the operation of steel making, and
recently in the manufacture of the alloys known as manganese steel, manganese
bronze and other metallic mixtures into which manganese enters as an essential
constituent, has made it desirable to produce metallic manganese on a commercial
scale in a state of the highest possible purity, and cheaply enough to permit of its
use in these operations. For the want of the pure metal manufacturers have
hitherto been compelled to employ the alloys of manganese and iron made in the
blast furnace and known as spiegel-eisen and ferro-manganese, these alloys
containing from six to eighty five per cent. of manganese with five or six per cent. of
carbon and small quantities of silicon phosphorous and other impurities. The most
persistent efforts heretofore made to produce, cheaply enough for industrial
purposes a manganese practically free from carbon and iron have failed.
The processes heretofore employed or proposed for the production of manganese
may be placed in two groups.
In one, an oxide of the metal (either in the form of the sesqui-oxide, or the
di-oxide) or the carbonate is intimately incorporated with finely divided carbon, and
subjected to an intense heat in crucibles whereby the reduction is effected.
As a result of many experiments conducted on this plan of reduction we have
satisfied ourselves that it is impossible to produce by it a metal free from carbon.
The manganese we have produced by numerous nodifications of this general. plan
invariably contained about six per cent. of combined carbon even when the quantity
of carbon employed was insufficient to effect a complete reduction of the oxides,
nor could this carbon be eliminated from the metal by fusing it, in the presence
of sundry fluxes with more oxides. These results confirm those of other
experimenters.
In another group may be placed those processes in which the chloride or fluoride
of manganese is reduced by subjecting it under various circumstances to the action
of sodium. By methods of this class manganese may be obtained chemically pure
but they have proved far too costly to be used commercially.
The electrolytic method of reduction has been experimentally attempted on a
small scale, but the impossibility of using a carbonaceous anode in this operation
because of the certainty of forming a carbonide of the metal is one of the several
difficulties which the electro-metallurgist has not been able to overcome.
Alloys of copper containing varying proportions of manganese have indeed been
made successfully on a commercial scale by the electric furnace method, but the
necessity of using electrodes of carbon in this method renders the production of the
pure metal impossible.
We will now proceed to describe our invention of a process for producing metallic
manganese entirely free from carbon and containing only such slight quantities of
iron and other impurities such as silicon, phosphorous, etc., as are within the

page_text: permissible limit in the manufacture of metals on a large scale, where the term
commercially pure is used to designate the product.
In the operation of our process the manganese ore composed substantially of
manganese di-oxide, and contaminated with more or less iron, is finely ground and
digested with sulphuric acid (Sp. Gr. 1.84) diluted with two or three times its volume
of water. The iron passes into solution while the oxides of manganese are only
slightly affected. We have found that the above named proportions of dilution for
the acid should be adhered to in order to obtain the most satisfactory results, since,
if a more concentrated acid solution be used, the manganese oxide will be powerfully
attacked and dissolved, while if a more dilute acid he employed the time
consumed in the removal of the iron will be unduly prolonged. The operation is
facilitated by constant agitation of the mixture so as to expose fresh portions of the
ore to the action of the acid.
When the removal of the iron is accomplished, the liquor is drawn off and the
purified ore is washed with water to remove all traces of the acid and is then dried.
If the operation has been conducted properly the percentage of iron in the ore is
thereby reduced to a few tenths of one per cent. The acid liquid may be treated
by well known methods for the recovery of the waste in the form of copperas.
In operating with a commercially pure ore, or where the presence of iron in the
metal is not objectionable, this preliminary purification will not of course be
necessary.
The ore is now to be reduced to the condition of a lower oxide, preferably to
that of manganese mon-oxide, by any convenient method. The reduction to
manganese mon-oxide presents several important practical advantages. Manganese
mon-oxide being the lowest known oxide of manganese, will demand less of the
reducing substance to subsequently remove its oxygen and this oxide is better
adapted for such subsequent reduction by reason of its being fusible at a much
lower temperature than are the other oxides of the metal.
For the reduction of the manganese di-oxide to a lower oxide we have found the
following method to answer satisfactorily.
The commercially pure native ore, or the commercially purified ore is introduced
into an oven having preferably the form of a horizontal cylinder and mounted so as
to permit of being rotated about a horizontal axis. The oven is provided with
suitable openings for the admission and exit of gases. In an oven answering to this
general description, the ore is heated to redness in a current of reducing gas, for
which purpose we may employ a petroleum vapour, hydro-carbon gases, carbon
monoxide, or water gas. By this operation, di-oxide and sesqui-oxide (corre-
sponding respectively to the chemical formulæ MnO₂, Mn,O) are converted
first to the protosesquioxide (Mn,O,) and then to the gray oxide or monoxide of
the composition MnO.
!
The final step of our process consists in reducing the manganese protosesqui-
oxide or manganese monoxide to the metallic state.
We accomplish this by heating it in contact with a metal capable of removing
and appropriating its oxygen and setting free the manganese. The presence of a
flux facilitates the reaction and the gathering into a single mass of the resulting
metal, which when no flux is used in the operation, is found disseminated
through the mixture in the form of globules or shot, which require to be separated,
collected, and re-melted.
In this operation we use a crucible or chamber formed of, or lined with, a
material free from carbon and preferably also free from silica.
For certain uses for which the metal may be found suitable, the presence of
silicon in small quantity, say to the amount of three per cent. is not detrimental and
for metal of this quality, the reduction of the manganese protosesquioxide or mon-
oxide may be performed in siliceous crucibles.
We have found the following mode of operation to yield the best results.
Manganese monoxide is introduced into a crucible or chamber lined with lime or
magnesia or other material free from carbon and silica and capable of resisting

page_text: the action of the flux, metallic aluminium is added in the proportion required to
effect the reduction of the manganese monoxide present (that is to say, in the
proportion of 55 parts of aluminium to 213 parts of manganese monoxide) and there
is also added a quantity of some suitable flux. This may consist either of fluorides
such as fluor-spar or cryolite or mixtures of both or in case the operation be
conducted in siliceous vessels of silicates of potassium sodium, calcium aluminium
and magnesium in various proportions. The mixture is then heated to the
temperature at which the reaction takes place. If desired however the manganese
monoxide intimately incorporated with a convenient quantity of the flux may be
introduced into the reducing chamber or crucible together with the aluminium in
the proportions above named and the mixture be then heated to the temperature
at which the reaction takes place. If instead of monoxide the protosesquioxide is
under treatment the proportion of oxygen-appropriating metal should be corre-
spondingly increased in accordance with the change in chemical equivalence
involved.
When the presence in the metal of silicon in small proportion is not objectionable
the reduction may easily and effectively be accomplished by either of the foregoing
procedures by the use of a readily fusible siliceous flux such for example as
powdered glass and the reduction may be effected in siliceous crucibles.
To avoid the contamination of the resulting metal with aluminium we have found
it preferable to add in the reducing operation somewhat less aluminium than would
be required to reduce the manganese oxide completely.
By careful observance of this precaution the quantity of aluminium remaining in
the product will be inappreciable.
By the several operations above described there results metallic manganese
entirely free from carbon and containing only such small quantities of iron, silicon
and other impurities that for commercial purposes it may be considered to be pure.
A product of such high grade of purity has not yet to our knowledge been made
on a commercial scale and we are enabled by our process to manufacture it at a
lower cost than has heretofore been possible.
The resulting metal exhibits the property of being quite stable in the air an
evidence of its freedom from carbon while all the so called manganese reduced in
contact with carbon after exposure to the air for a few days only disintegrates and
falls to powder.
The residium containing the aluminium oxide may be treated if found desirable
to regenerate the aluminium.
If instead of pure manganese an alloy of manganese is desired the metal which
it is wished to alloy with the manganese may be introduced either with the
aluminium which is used as the reducing agent or with the ore as in the herein
described case where a ferruginous manganese ore is employed in the manufacture
of a ferromanganese entirely free from carbon.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
First. In the manufacture of metallic manganese or manganese alloys free from
carbon the herein described process which consists in reducing the ore to the
condition of a lower oxide and then reducing such lower oxide to the metallic state
by heating it, in a reducing chamber free from carbon in contact with substantially
the chemically equivalent quantity of a metal capable of removing its oxygen
substantially as hereinbefore described.
Second. In the manufacture of metallic manganese or manganese alloys free from
carbon the herein described process which consists in reducing the ore to the
condition of a lower oxide and then reducing the said lower oxide to the metallic
state by heating it in a reducing chamber free from carbon and silica in contact
with substantially the chemical equivalent quantity of a metal capable of reducing
its oxygen substantially as herein before described.

page_text: Third. In the manufacture of metallic manganese or manganese alloys free from
carbon the herein described process which consists in digesting the manganese ore
with diluted sulphuric acid then reducing the purified ore to the condition of a
lower oxide and then reducing such lower oxide to the metallic state by heating in
a reducing chamber free from carbon, in contact with substantially the chemically
equivalent quantity of a metal capable of removing its oxygen substantially as
herein before described.
Fourth. In the manufacture of metallic manganese or manganese alloys free
from carbon the herein described process which consists in digesting the manganese
ore with diluted sulphuric acid then reducing the purified ore to the condition of a
lower oxide and then reducing such lower oxide to the metallic state by heating it
in a reducing chamber free from carbon and silica in contact with substantially the
chemically equivalent quantity of a metal capable of removing its oxygen substan-
tially as hereinbefore described.
Fifth. In the manufacture of metallic manganese or manganese alloys free from
carbon the herein described process which consists in reducing the ore to
manganese monoxide then reducing said monoxide to the metallic state by
heating it in contact with substantially the chemically equivalent quantity of a
metal capable of removing its oxygen substantially as hereinbefore described.
Dated this 3rd day of January 1893.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.