Improved Process of Producing Metallio Alloys.
Year: 1893

page_text: Date of Application, 31st Jan., 1893-Accepted, 4th Mar., 1893
GOBLE LETE OF FOLEVATION.
Improved Process of Producing Metallio Alloys.
We WILLIAM HOUSTON GREENE of 204 North 36th Street and WILLIAM
HENRY WAHL of 1436 North 13th Street in the City of Philadelphia and State
of Pennsylvania, United States of America Chemists 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 provide a cheap and efficient means for the pro-
duction of certain metallic alloys and the process according to our invention consists
substantially in utilizing metallic silicides for the reduction of certain difficultly
reducible oxides, or of such as cannot be reduced by means of carbon without the
introduction of an objectionable quantity of carbon into the resulting metal.
In the term metallic silicides we wish it to be understood that we include all
metallic compounds or mixtures in which the element silicon is present in such
quantity as to justify their designation as siliciferous alloys, or siliconized alloys
terms which are well understood by metallurgists. It is not practicable in this
definition to name a minimum quantity of silicon that would suit all cases, for the
reason that silicon effects the physical properties of differout metals differently and
what would be a small proportion for one metal would be a large proportion for
another, and because the presence of other elements may materially alter the pro-
perties of the alloy. Thus in commercial cast iron the proportion of silicon may
vary from a trace to about 3-5 per cent. as a maximum. Ordinary cast iron cou-
taining 3-5 per cent. of silicon we would therefore not consider to be a silicate but if'
an iron containing 3-5 per cent. silicon at the same time contain a proportion of
carbon, not exceeding one per cent., we would consider it for our purposes to be a
silicate. Other metals than iron we consider to be silicides whoo they contain as
much as two per cent. of silicon.
When such silicides are heated with metallic oxides in the presence of a suitable
base, such as limo, magnesia or alumina the oxygen of the oxide combines with the
silicon forming silica which at once unites with the base forming a fusible silicate
that separates as slag while tho motals set free then combine together forming an
alloy.
By suitable regulation of the proportions and character of the silicide, nictallio
oxide and flux, or by repeating the operation of fusion with fresh additions of ore,
or by the addition of any given metal to the original charge, or to the product of
the first reaction, we can produce metallic alloys or mixtures having any required
composition.
Our process it will be observed enables us to effect the reduction of numerous
metallic oxides without the aid of carbon, a circumstance which in certain cases,
especially in the manufacture of metals used in the production of certain special
steels is of vital importance. In fact we effect the reduction of metallic oxides under
entirely new conditions which enable us to produce with advantage not only well
known and useful metallic alloys and compositions, but also others heretoforo
unknown having new and valuable properties.
As an example we will cite the case of manganese steel. By the present method
of manufacturing this alloy, which consists in the addition of ordinary ferro-
manganese to fluid iron, the proportion of manganese that can usefully be introduced
into the product is limited by the carbon which to the amount of five to six per cent.,
is present in the ferro-manganese and which cannot be eliminated therefrom because
of its affinity for manganese.
By our process we are able to produce an alloy of iron and manganese containing
on amall
mamit nf the introduction of a much larger

page_text: proportion of manganese into steel than by the present method without introducing
so much carbon as to overstep the permissible limit.
It is evident that in all our operations whether performed on the hearth of a
furnace or in crucibles, the presence in either, or in the flux, of free carbon, must
strictly be avoided.
Wo will now describe our process in detail taking as an example its application
to the manufacture of manganese steel. In this case we employ the commercial
products known under the names of ferro-silicon, silico-spiegel and silico-ferro-
manganese which may be described as silicides of iron or of iron and manganese
containing a variable proportion of silicon usually from six to thirty per cent., and a
comparatively low percentage of carbon. Since, for reasons previously stated the
absence of carbon in notable proportion is of great importance in manganeso stecl
we employ for our purpose a silicide containing as high a proportion of silicon and
as low a proportion of carbon as possible. Silicon irons and spiegels containing as
much as fifteen or twenty per cent. of silicon and with carbon not exceeding one per
cent. can readily be obtained and by special selection of ores and fluxes can be made
even richer than this in silicon. As a rule, also the quantity of carbon present in
such silicides varies with the silicon in an inverse ratio, carbon decreasing as silicon
increases and vice versa.
A silicide which may be either ferro-silicon or silico-spiegel of suitable
composition having been selected, it is melted on the hearth of a furnace
having preferably a lime or maguesia lining, and when melted a quantity of the
monoxide or protosesqui-oxide of manganese (preferably the former) with which
there has previously been incorporated a quantity of any suitable flux, is added
thereto.
The reaction takes place promptly, the silicon of the ferro-silicon seizes upon
the oxygen of the manganese ore, and is thereby converted into silicic oxide which
forms with the flux a liquid slag, while the manganese set free by the reduction of
the ore combines with the molten iron set free from the silicide.
Agitation of the charge will of course faciltate the operation by bringing more
quickly the ingredients of the charge into intimato contact. The whole charge of
manganese ore and flux may be added to the ferro-silicon at once, or the addition
may be made by portions until a sufficient quantity of the oxide has been employed
to utilize the reducing power of all of the silicon that was present in the ferro-
silicon, thus reducing a chemically equivalent quantity of manganese oxide to the
metallic state.
00
Iron
Silicon
Carbon
00 per
10
1
per cent,
per cent.
As the reaction will take place according to the equation
2 MnO + Si = SiO, + 2 Mn.
we employ silicide and manganese oxide in quantities that satisfy the above
proportions i.e. for every 28 parts of silicon in the silicide, 142 parts of manganese
monoxide are added and the quantity of lime, magnesia or alumina or a mixture of
these, that will completely combine with the silica to form a fusible silicate. We
havo found it necessary to use a larger quantity of manganese ore than that
required by theory, for the reason that a certain quantity of the manganese oxide
is always seized upon by the silica and passes into the slag in the form of manganese
Bilicate.
We have found the following proportions by weight of charge to yield good

page_text: In the preparation of a manganese steel containing the same percentage of carbon
by melting decarburized iron with ordinary ferro-manganese containing 80 per cent.
manganese and 5-5 per cent. carbon the resulting metal would contain 92.23 per cent.
iron and only 7.27 per cent. manganese. Or making the comparison on the basis of
equivalent quantities of manganese the manganese steel made from the ordinary
ferro-manganese would contain for 20°7 per cent, manganese, 1·4 per cent. carbon
that made by our process would contain for 7-27 per cent. manganese only
0.18 per cent.
By strictly analogous methods of operation other special steels or alloys of iron
may be formed, thus the substitution of tungstic oxide for the manganese oxide in
the previously described operation will result in the formation of an alloy of iron
and tungsten applicable to the manufacture of tungsten stool.
In many cases it is obvious that a metal of the desired composition may be
obtained directly by one operation on the furnace hearth. Thus for the production
of a manganese steel of a given composition the required proportions of scrap
wrought iron and forro-silicon of a suitable composition may be melted on the
hearth, in contact with the manganese oxide.
In the manner described, alloys of copper with difficultly reducible metals may be
obtained by fusing appropriate oxides with copper silicide, and other silicides will
doubtless be found useful for similar purposes.
We are aware that in the manufacture of steel by what is commonly known as
the open hearth process pig iron and scrap containing a small and varying proportion
of silicon are melted in contact with oxides of iron, and that the chemical reaction
which takes in this operation is similar to that which occurs in the operation of our
process. The carbon and silicon of the iron, both of which but essentially
the first, it is the object of the open hearth steel process to remove, are burned out
by the oxygen of the iron ores. But with the similarity of the chemical reactions
the analogy between our process and the open hearth steel process ceases.
In the open hearth the process is essentially one of decarburization, and the
separation of the small quantity or silicon from the pig iron of the charge is
merely an incident. The presence of silicon in the pig irons employed in this
operation is wholly unnecessary, and in the choice of such pig irons those which
contain but little silicon are preferred, and its total absence does not in the
least affect the operation of the process.
In the open hearth process the silicon of the cast iron is an accidental and
objectionable constituent which it is desirable to remove.
On the contrary for our purpose the silicon is absolutely essential, and the higher
its per centage the more efficient does our process become.
We are also aware that in the commercial reduction, remelting and casting, of
many metals and alloys it is difficult, or impossible, to prevent the retention or the
formation of small quantities of oxide and the absorption of certain gases such as

page_text: carbonic oxide and atmospheric oxygen by the metals, and that the presence of
even very minute quantities of such oxide and occluded gases has a very
unfavourable influence on the strength, ductibility and other desirable qualities
of the metal aud renders it extremely troublesome to roll or obtain castings from
it free from blow-holes. These difficulties are due to the fact that the presence of
slight quantities of oxides and occluded gases prevents the intimate coalesence of
particles of the metal and the production of a perfectly homogeneous texture.
We are also aware that it has long been the practice to counteract the
deleterious influences, above named by subjecting the metal prior to its with-
drawal from the furuace, or cupola, or crucible, or in the ladle just before pouring
into the mould to a species of purification or refining in which the objectionable
traces of oxides or harmful occluded gases are removed by the addition to the
reduced or re-melted metal or alloy while in the molten state, of minute quantities
of some powerful deoxidising agent. For the purpose of such purification, or
refining, phosphorous, manganese, aluminium, magnesium and silicon are more or
less commonly used sometimes in the form of compounds or alloys, and sometimes
in the elementary form.
As examples we cite the addition of phosphorous in small quantity generally in
the form of phosphor-copper or phosphor tiu to copper brass, and bronze, to burn
out the traces of cuprous oxide and make a stronger and tougher metal or alloy the
addition of minute quantities of metallic magnesium to metallic nickel to remove
occluded carbonic oxide of small quantities of ferro-manganese or ferro-silicon to
molten steol in the open hearth process at the close of the melting and of copper
tin and zinc silicides to metallic copper tin and zinc for the same general purpose
to insure the production of homogeneous metal and sound castings.
These operations though depending on the general principle of chemical reduction
are not comparable with our invention which differs radically in the object attained
in the mode of procedure and in the scope of its application.
The silicides in the cases above referred to, are added to metals previously
reduced by agents other than silicon, and are used in a finishing operation for the
purpose of removing small and generally minute quantities of certain objectionable
impurities unavoidably contracted in the previous operation of reduction by carbon
or in the re-melting, and if they are added in quantities greater than they may be
required for the purification of the metals this is done for the purpose of forming a
silicon alloy, which is foreign to the purpose of our invention.
Our process relates exclusively to the reduction of oxidized ores of metals by
bringing such oxides in proper proportion in contact with metallic silicides, and
effecting the reduction of the ores solely by the silicon of the silicides with the aid
of heat.
This metallurgical operation which we have invented differs substantially and
radically from the above described operation of purification of metals contaminated
with small quantities of oxide or by occluded gases acquired in the process of their
reduction by carbon, or in the re-melting and we accordingly disclaim such uses of
metallic silicides as being foreign to the purpose of our invention.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manuer the same is to be performed we declare that what we
claim is :-
1. In the manufacture of metallic alloys the herein described process; which
consists in heating to a suitable temperature, and in presence of suitable fluxes, a
metallic oxide, in contact with a silicide of a metal capable of alloying with the
reduced metal whereby the primary reduction of the metallic oxide to the metallic
state is effected by the silicon of the silicide employed and the reduced metal alloys
with the base of the silicide.
2. In the manufacture of metallic alloys the herein described process; which
consists in heating to a suitable temperature in a furnace, chamber, or crucible free
Samahan

page_text: silicide of a metal capable of alloying with the reduced metal whereby the primary
reduction of the metallic oxide to the metallic state is effected by the silicon of the
Bilicide employed and the reduced metal alloys with the base of the silicide.
Dated this 31st day of January 1893.
J. H. JOHNSON & Co.,
Agents.