Improvements in the Manufacture of Alloys and in the Purification of Metals and Alloys.
Year: 1892

page_text: Date of Application, 25th July, 1892-Accepted, 25th Aug., 1893
Improvements in the Manufacture of Alloys and in the Purification
of Metals and Alloys.
I, Dr. JOSEPH BAXERES TORRES, of 7 Rue Lafitte, Paris in the Republic of
France, 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 :-
This invention is based upon the employment of the following bodies or compounds,
or alloys thereof, no matter whether they are alloyed with each other, or with
other bodies, or metals.
Silicon.
To combine with nitrogen, and to free from it such alloys and metals to which is
might prove injurious to their physical properties; to reduce the acids of phosphorus
and to drive this element from such alloys and metals to which it may impart
brittleness and prove objectionable. These bodies reduce a great number of salts
among others the chlorides, the sulphurets, the phosphor compounds forming volatile
compounds aud consequently driving these metalloids from the metallic alloys
under treatment. They also form readily fusible alloys with some high melting
metals.

page_text: making it possible to alloy metals which do not unite easily, by lowering the melting
point of that one of the metals most difficult to melt. In several instances if either
antimony or bismuth remains in the alloy they may be found useful on account of
their hardening properties but if found injurious they may be easily driven off by
calcination.
To absorb the nitrogen from metals and alloys in which this element may prove
injurious to form easily-fusing compounds with phosphorus and sulphur and to
drive such bodies from alloys and metals which are thus purified; to reduce the
oxides which may be present in the alloy so as to render more homogeneity; to form
compounds rich in carbon so as to introduce this element into such metals or alloys
when needed.
In the whole the bodies herein named will be found useful on account of their
peculiar properties of 1stly, absorbing oxygen or nitrogen thus reducing the oxides
which form impurities and impart brittleness to metals and alloys; 2ndly, of
decomposing some carbon compounds such as carbonic acid and carbon oxide which
destroy the homogeneity of such metal and alloys; 3rdly of reducing the oxides and
salts; 4thly of driving off phosphorus arsenic and sulphur by forming easily fusible
compounds with these elements; 5thly of forming easily fusing alloys with some
metals and alloys on account of their low melting point. 6thly absorbing carbon,
boron, silicon, titanium, tungsten, molybdenum, and of forming compounds rich in
these elements which may thus be easily introduced with new alloys if required.
All these properties are utilized to refine metals and alloys and to form new
alloys with metals which are now difficult to mix or combine together.
These various substances possess peculiar properties as regards their action upon
various metals and alloys. These properties are as follows.
If in a bath of any cast metal a suitable quantity of one or more of the bodies
named above or of their compounds or alloys, be introduced, it will be found that
scum forms at the surface, while at the same time gaseous compounds are generated,
which carry away with them the impurities originally contained in the metal. Let
us take for an example a bath of 99% phosphoric or sulphurous cast iron in which
is put, say 1% aluminium. It will be found that the phosphorus and sulphur are
expelled almost immediately and more or less completely according to the pro-
portions of the aluminium employed in the conditions respectively, of sulphurous
acid (in the form of gas) and phosphate of alumina in the form of scum collecting
at the surface of the cast iron bath, the metal of which is thus purified. If instead
of acting upon one single metal, a ready-made alloy of several more or less impure
metals be operated upon, i.e. if one or more of the purifying bodies or agents
mentioned above be introduced therein (or any of their compounds or alloys) the
molecules of the metal constituting the alloy will be found to get closer together,
owing to the elimination of the impurities which before kept them apart. Taking
for example an ordinary alloy known as type-inetal which as is well-known consists
of lead and antimony. Its grain is very crystalline owing to the presence of
antimony and consequently its molecular resistance is very insignificant. In a bath
composed of say 99-75% of an alloy such as this, melted at the lowest possible
temperature, I introduce a suitable quantity of one or more of the purifying agents
named, notably aluminium say 25%. The mass will at once coagulate and in order
to restore its previous fluidity it is necessary to keep raising the temperature for a
period of from a quarter of an hour to 20 minutes. We now see aluminous scums
rising to the surface of the bath and charged with all the impurities contained in
the two metals (lead and antimony), alumina having been formed through the
interior oxidation of the aluminium, at the expense of the oxides originally interposed
between the molecules, and now reduced. If the alloy thus purified be melted and

page_text: after cooling broken, it is found that its texture has been considerably altered, as
nstead of presenting crystals with large facets, it now has a fine and dense, almost
amorphous, grain. Consequently by expelling the particles of oxides, or more
correctly speaking, by destroying these particles through reduction, the aluminium
has caused the two metals to unite more closely and thoroughly or to come into
more intimate contact with each other by intermingling their respective molecules
It will moreover
in the condition of smaller and more compact grain than before.
be understood without difficulty that certain non-oxidized portions of the aluminium
added at the same time act as a kind of cement between the inolecules of the two
other metals and thereby assist in rendering still more compact and homogeneous
the texture of the alloy. The foregoing example is only given here as one well
characterizing the invention, but the natural process is exactly the same whatever
the nature of the alloy, the number of the metals of which it consists, their
condition of purity or otherwise, and the purifying bodies or the compounds or
alloys of the same employed in their treatment.
The purifying bodies or agents in question have, however, other properties
besides those mentioned. Both by their purifying action and by bringing the
molecules into closer contact with each other they facilitate the formation of alloys
of metals having little or no affinity with each other and of which therefore it has
hitherto been found impossible or impracticable to obtain homogeneous alloys. In
such alloys the purifying bodies or compounds or alloys thereof will if introduced
either simply act by reduction or simultaneously by reduction and adhesion and
form one of the component parts or ingredients of the alloy finally obtained.
In each particular case a complete analysis of the body to be treated must be
made by which it may be ascertained which are the impurities to be removed, &
by reference to the 6 tables given above the body or bodies to be employed may
be determined, according as it is intended to utilize them either for purification
only, or both for purifying and alloying the metal or metals under treatment
with the bodies added. The following are examples of the performance of this
process.
I. Platinum and silver will not form a homogeneous and ductile alloy on account
of the quantity of occluded gases oxygen and oxide of carbon which they absorb
while melting. If one or more of the following bodies are added the oxygen is
driven off and the oxide of carbon is reduced, the alloy obtained is then homo-
geneous and may be drawn or rolled.
Aluminium, magnesium, manganese, antimony, bismuth, etc., it will be found that
the two metals will combine and while being purified form a multiple and perfectly
homogeneous alloy. To obtain a result such as this generally but very small
quantities of the purifying agent need be employed. Thus one quarter to one half
per cent. of aluminium has enabled me to produce very homogeneous alloys of
platinum and silver suitable for all the different manipulations usual in working
precious metals into jewellery, plate or coins.
II. It is well known that nickel only with great difficulty mixes with more than
5 per cent. of chrome. By adding to these metals (nickel and chrome) even a very
small quantity of one of the purifying bodies, particularly aluminium, the nickel
may be thoroughly saturated with chrome and a very hard alloy obtained, pre-
senting needle-shaped crystals and enabling other alloys with chrome such as steel,
nickel and chrome to be readily formed.
III. Hitherto in the manufacture of chrome-steel it has been an unavoidable
necessity to employ chromic iron containing 60 per cent. of chrome which can only
be produced in a crucible with great difficulty and is therefore very expensive. If
natural chrome-iron be treated with antimony a double antimonide of iron and
chrome is readily produced, being particularly rich in chrome, as antimony has a
great affinity for chrome, even where iron is present, so that it may be said that
the chrome is concentrated by this process. An advantage in adding antimony to
chrome-iron is that it reduces the high melting point of this alloy, the melting
point of the alloy of antimony with chromium and iron being comparatively low.

page_text: This
In this way an alloy without blow holes and melting at a low point, and with a
large amount of chronium is obtained. This antimonide may be added to steel in
the proportion required to impart to it the desired quantity of chrome.
method is economical and easy to carry out. Even if the proportion of antimony
could injuriously influence the quality of the steel produced, it would be easy by
keeping out air and applying heat, to expel the whole or part of the antimony
from the melted metal which would then be volatilized.
What is here stated concerning chrome will evidently apply also, to tungsten and
titanium. But in this example the antimony performs a double object. First by
forming the double antimonide of iron and chrome, it facilitates the concentration
of the chrome and its introduction into the steel under treatment; and then, upon
entering the steel, the whole or part of the antimony exercises a reducing or
eliminating action on the impurities contained in the steel bath. The operation
here described therefore may be rightly considered as covered by the general
principle of this invention having the purification and alloying of metals for its
main object. In fact the example just given may be regarded as illustrating the
invention most completely.
The bodies herein termed "purifying" bodies or agents besides facilitating
certain concentrations as have just been explained, enable certain pure and homo-
geneous alloys to be obtained by methods which are both simpler and more
economical than the direct methods hitherto employed. In most cases where it is
desired to form alloys, the process of first melting the metals to be united, then
mixing, and lastly purifying them, is indeed scarcely advantageous or convenient.
Let us say, for instance, that it is desired to alloy and purify two metals of widely
different melting temperatures. If they are to be mixed in a melted condition the
temperature before and during the purifying stage will have to be raised to suit the
least fusible of the two metals, and therefore will be much higher than that required
for melting the most. fusible metal. This latter metal is therefore heated to an
excessive degree and consequently becomes either partly volatilized, or oxidized;
therefore in one case there will be actual loss of metal, and in the other case, the
necessity of emp oying a larger amount of the purifying agent, i.e. in either case a
loss in the end. In such an instance therefore it would certainly be advantageous
to proceed differently. Now according to this invention, instead of melting both
metals of different melting points, one only of these metals is melted. To this is
added an alloy or compound, melted or otherwise comprising the second of the two
metals to be allowed and one or more suitable purifiers. Assuming that a very
pure and homogeneous alloy of copper and zinc is required; the copper is first
melted, and into the copper bath is then introduced either phosphuret or antimonide
of zinc. The result will be that the desired alloy will be purified as it is formed;
the alloy obtained may or may not have a certain quantity of the purifying agent
(antimony or phosphorus) in excess, which, if present, may modify the peculiar
properties of the final alloy. Owing to the fact that the alloy has formed
and been purified at the same time, the zinc could not become volatilized and
therefore a very small quantity of the purifier is sufficient to effect the desired
object.
From a commercial point of view there is another advantage still. in operating
by this indirect method: the purifying compounds or alloys in most cases have
very low melting temperatures in comparison with those of the metals to be alloyed.
In the instance given (copper and zine), particularly, the zine may be melted first,
and phosphuret of copper, melted or otherwise, added.
Such combinations may be altered in a great number of cases, according to the
amount of impurities to be driven from the metal or alloy, their quantity and
quality, the melting point of the metal or alloy, and the new. alloy to be formed
by introducing one or other of the metals required. These instances are only
given for demonstration, and the inventor does not bind himself to use always
the same proportions or the same elements or alloys to purify, refine alloy, harden
or form new alloys.

page_text: Having now particularly described and ascertained the nature of my said inven-
ion and in what manner the same is to be performed, I declare that what I
laim is :-
The general process herein described enabling metals and alloys to be purified
and such alloys to be readily formed the said process consisting in adding to the
path of melted metals one or more of the following purifying bodies either in their
natural condition melted or otherwise or in the condition of alloys or compounds :-
Sodium, potassium, and other alkaline metals.
Aluminium, magnesiumi barium and other alkaline carthy metals.
Antimony, bismuth, tungsten, molybdenum, manganese, titanium.
Phosphorus, boron and silicon.
These bodies acting substantially as and for the purpose described.
W. P. THOMPSON & BOULT,
Agents for Applicant.