Process and Apparatus for the Conjoint Manufacture of Metallic Peroxides and Caustic Alkalies or Alkali Earths.
Year: 1894

page_text: France),
Date of Application (in United Kingdom), 30th Nov., 1894
Complete Specification Left, 28th Aug., 1895-Accepted, 5th Oct.,
1895
PROVISIONAL SPECIFICATION.
Process and Apparatus for the Conjoint Manufacture of Metallic
Peroxides and Caustic Alkalies or Alkali Earths.
I, LEON PAUL HULIN, of Modane (Savoie) France, Civil Engineer, do hereby
declare the nature of this invention to be as follows:-
The invention which forms the subject of the present application for Letters
Patent consists in a process and apparatus for the manufacture conjointly and
complete in all respects, of peroxides of certain heavy metals and alkaline
The heavy
protoxides (i.e. of the alkalies properly so called and alkali-earths).
inetals to which my process applies are those of which the superior peroxides play
the part of an acid, such as tin, titanium, and others, and in particular of those
which cannot be transformed into these acid peroxides by the mere calcination of
the metal alone in contact with air. Such are of these latter, lead, antimony,
chromium, manganese, etc., etc.
Succinctly defined and characterized, my process consists in alloying the heavy
metal to be peroxidized with an alkali metal or alkali-earth metal; heating the
alloy to about a dull red heat and in contact with the oxygen of the air whereby
the alloy becomes oxidized, the product of the oxidation being a combination of
peroxide of the heavy metal and of protoxide of the alkali metal which product is
preferably separated from the alloy not yet oxidized in order to avoid loss of
peroxide.
The acid function of the peroxides of the heavy metals is so strongly promoted
by the oxidation of the alkali metal in the state of alloy that I consider my process
is susceptible of replacing that which consists in peroxidizing the heavy metals by
calcining one of their lower oxides with an alkaline nitrate. For greater clearness
and precision in the description of the operations, I will hereinafter describe by
way of example the manufacture of peroxide of lead and soda.
I take an alloy of lead and sodium of any origin, but preferably that which I
obtain by my electrolytic process forming the subject of another application for
Letters Patent dated the 28th day of November 1894 No. 23117. Theoretically
this alloy should be formed of equal equivalents of lead and sodium, but in practice
I prefer that it should be richer in lead than in sodium in order that it may be
easily handled and because the operation is better performed. The alloy is fused
at a temperature verging on a dull red in an iron vessel expressly arranged for the
access of air. Under these conditions there forms upon the surface of the fluid
bath a deep brown scum composed of the oxide of the alkali metal united with
a variable quantity of lead oxide but whilst the alkali metal has remained in

page_text: the state of protoxide, the lead has passed into the state of di-oxide, that is to
say to a degree of oxidation superior to that which would be produced at the
same temperature out of the presence of the alkali metal which accompanies it
in the alloy. Under these circumstances the lead thus becomes peroxidized by
the contact of the air at an elevated temperature by favour of the alkali metal
with which it is associated. The peroxide and alkaline oxide are combined
together in ill defined proportions it is true, and they form a brown pasty or
liquid layer on the surface of the alloy, which forms my first product and should
be removed at regular intervals so as to expose the alloy to the air and permit
the latter to further oxidize it.
This skimming may be performed either by hand
or by suitable mechanical means such as that hereinafter described with reference
to the apparatus.
The composition of the plumbate thus obtained is variable and depends on the
manner in which the operation is conducted. If the products of the oxidation
be rapidly removed a maximum of peroxide of lead is obtained. If on the other
hand the layer of oxides is allowed to cover the alloy, the subjacent alkali metal
oxidizes at the expense of the peroxide of lead which covers it and which is
reduced to the metallic state and returns into the alloy so that I then obtain a
compound richer in alkali and containing much less peroxide of lead than in the
previous case. It is in consequence therefore of this retrograde action that I
remove the product as rapidly and uninterruptedly as possible. This retro-
gression is the cause of the product not being a well defined anhydrous plumbate
of soda. After the operation there remains an excess of metallic lead still
containing a little alkali metal which is utilized in the manufacture of the alloy.
By varying the temperature of the oxidizing operation while still retaining
the same principle I may obtain at will alkaline oxide united to the heavy
peroxide in a state of fine powder by a species of sublimation. To effect this
I heat the alloy to a higher temperature (bright red) in an iron or steel vessel
closed by a cover provided with two pipe connections by one of which air is
introduced. The superheated alloy becomes ignited and the fumes composed of
the combined oxides are conducted by the other pipe into a series of large closed
chambers in which they are collected in the form of very fine powder.
apparatus for carrying out this operation will be understood without further
description. The air used may be previously heated and it may be injected into
the midst of the alloy by means of a dip pipe for example, so as to produce a
stirring effect and an energetic oxidizing action. Many and various arrangements
of apparatus based on these principles may be devised for the purpose.
An
The
Such then are in principle the fundamental characteristics of my process.
first result is, as before explained, the formation of an alkaline compound of a
metallic acid (plumbate, chromate, staunate, etc.). These products may either be
disposed of for use as such in other manufactures or be treated for the separation
of the acid metallic peroxide from the alkali. This separation may be effected by
different means which vary according to the nature of the compound to be
decomposed
(1.) In order to decompose plumbate of soda, I digest it in a sufficient quantity
of water whereby the alkaline oxide is at once strongly hydrated which becomes
dissolved with disengagement of heat and gives up the peroxide of lead in the
state of a very fine powder resembling a precipitate. On letting rest the peroxide
powder deposits and may be separated by decantation or filtration, and it is then
washed in pure water which serves again for the succeeding operation. The heavy
peroxide is then dried (if necessary) and the caustic soda is recovered from its
solution by evaporation as now practised, or is utilized without further treatment.
When, owing to various circumstances, the alkaline solution contains oxide of lead
in solution I separate the latter by subjecting the alkaline solution to electrolysis
which precipitates the metal upon the electrodes and thus completely purifies the
liquid. A more generally known process consists in substituting lime for the alkali
and digesting this base in a solution of the alkaline salt of a metallic acid

page_text: (chromate, stannate, etc.,) then separating the solution of caustic alkali which has
been freed from the insoluble lime salt of a metallic acid which is formed, and,
lastly, liberating the peroxide by saturating the lime by means of a suitable acid
such as sulphuric acid.
(2.) In order to obtain the anhydrous alkaline oxide from the plumbate of soda,
I utilize the retrograde action before referred to which occurs when the layer of
oxides is allowed to cover the alloy. By the adaptation of this special reaction
to my process, I can obtain anhydrous alkaline oxide, but I destroy the peroxide
by reforming the heavy metal which is then returned into the manufacture of
the alloy.
The operation is performed in a neutral atmosphere by placing in a closed vessel
of iron for example, alkaline plumbate as poor as possible in PbO, with an excess
of lead sodium alloy; by heating and continually stirring the whole I effect the
reduction of the peroxide to the metallic state by the sodium of the alloy and
the formation and setting free of the anhydrous alkaline oxide. I also obtain the
same result by mixing the alkaline alloy with another reducible metallic oxide.
In describing the fundamental operations I have supposed them to be inter-
mittent and capable of being performed without any special apparatus. I will
now proceed to describe a combination of my process with the electrolytic
production of alloy, forming by their reunion a continuous operation for the
complete manufacture of metallic peroxides and alkaline oxides upon the principle
forming the subject of the present application for Letters Patent.
The apparatus which I employ in this case is illustrated by way of example in
the accompanying drawings for the purpose of clearly shewing how my system is
practically applied to an electrolytic crucible by adapting it to my purpose,
and also the mechanical arrangements for ensuring the continuity of the
manufacture.
A is an electrolytic apparatus for producing an alloy of lead and sodium by the
electrolysis of sea-salt (for example) in a state of igneous fusion, which apparatus,
considered separately, may be of any principle or system. The fused alloy is
maintained by means of a suitable supply at, say, the level a. At one side of this
crucible is applied the special apparatus B of my invention in which is produced,
and from which is extracted, the peroxide of lead united with oxide of sodium.
The apparatus B consists of a cylindro-conical open vessel communicating at
bottom, by means of two superposed passages C, D, with the lower part of the
electrolytic part, these channels serving to intimately connect the two parts of the
apparatus. The alloy is maintained at a sufficient height to prevent the electrolyte
passing through the channel C, so that the alloy alone passes into B which is almost
completely filled, say, up to the level b more or less. E is a disc provided with a
large opening at its centre which divides chamber into two spaces communicating
by said opening; from the diaphragın E rises a cylindrical partition open at its
upper end.
F is a vertical shaft on which are mounted:-(1) in the lower
chamber, a pallet wheel G, shewn in plan in Figure 3, (2) in the conical portion of
the upper part of the chamber, curved inclined pallets H (shewn in elevation in
Figure 1 and in plan in Figure 2) which scrape the conical sides of the chamber.
I is an overflow spout at one side of said chamber.
The action will be readily understood. The electrolytic crucible being in
normal operation and charged with alloy, the shaft is rotated so as to cause
the wheel (i to carry the bath of molten alloy in the direction of the arrows and
bring it in contact with the air and immediately the layer of oxides b forms upon
the surface the blades H in revolving immediately project said oxides towards the
sides and by their inclined form cause them to rise up the sides and overflow at
the spout I into a receptacle. The impoverished alloy returns through channel I)
into A to he again enriched and returns through C to be oxidized in a continuous
manner.
Instead of the vessel B with revolving stirrers, I may employ the system of
closed vessel in which the alloy is heated to a higher temperature, into which is

page_text: introduced air to ignite the alloy, and extract the products of rapid combustion in
the form of condensable fumes, as previously described.
Dated this 30th day of November 1894.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
Process and Apparatus for the Conjoint Manufacture of Metallic
Peroxides and Caustic Alkalies or Alkali Earths.
I, LEON PAUL HULIN, of Modane, (Savoie), France, Civil Engineer, 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 invention which forms the subject of the present application for Letters
Patent consists in a process and apparatus for the conjoint production of peroxides
of certain heavy metals and protoxides of the alkali and alkali-earth metals. The
heavy metals to which my process applies are those of which the higher oxides
play the part of an acid, such as tin, titanium, and others and in particular those
which cannot be transformed into these acid peroxides by the mere calcination of
the metal alone in contact with air. Such are of these latter lead, antimony,
chromium, manganese, etc., etc.
Succinctly defined and characterized, my process consists in alloying the heavy
metal to be peroxidized with an alkali metal or alkali-earth metal; heating the
alloy to about a dull red heat and in contact with the oxygen of the air whereby
the alloy becomes oxidized, the product of the oxidation being a combination of
peroxide of the heavy metal and of protoxide of the alkali metal. This product
should be separated from the alloy not yet oxidized in order to avoid loss of peroxide.
The acid function of the peroxides of the heavy metals is so strongly promoted
by the oxidation of the alkali metal in the state of alloy that I consider my
process is susceptible of replacing that which consists in peroxidizing the heavy
For greater
metals by caleining one of their lower oxides with an alkali nitrate.
clearness and precision in the description of the operations, I will hereinafter
describe by way of example the manufacture of peroxide of lead and soda.
I take an alloy of lead and sodium of any origin, but preferably that which I
obtain by my electrolytic process forming the subject of another application for
Letters Patent dated the 28th day of November 1891, No. 23,117. Theoretically
this alloy should be formed of equal equivalents of lead and sodium, but in practice
I prefer that the alloy should be richer in lead than in sodium in order that it may
be easily handled and because the operation is better performed. The alloy is
fused at a temperature verging on a dull red in an iron vessel expressly arranged
for the access of air. Under these conditions there forms upon the surface of the
fused bath a deep brown scum composed of the oxide of the alkali metal united
with a variable quantity of lead oxide but whilst the alkali metal has remained in
the state of protoxide, the lead has passed into the state of di-oxide, that is to
say to a degree of oxidation superior to that which would be produced at the same
temperature out of the presence of the alkali metal which accompanies it in the
alloy. Under these circumstances the lead thus becomes peroxidized by the
contact of the air at an elevated temperature by favour of the alkali metal with
which it is associated. The peroxide and alkaline oxide are combined together in
ill defined proportions it is true, and they form a brown pusty or liquid layer on
the surface of the alloy. This layer, which forms my first product, should be
removed at regular intervals so as to expose the alloy to the air and permit the
latter to further oxidize it. This skimming may be performed either by hand or

page_text: by suitable mechanical means such as that hereinafter described with reference to
the apparatus.
The composition of the plumbate thus obtained is variable and depends on the
manner in which the operation is conducted. If the products of the oxidation be
rapidly removed a maximum of peroxide of lead is obtained but if the layer of
oxides were allowed to cover the alloy, the subjacent alkali metal would be oxidised
at the expense of the peroxide of lead which covers it and which would become
reduced to the metallic state and return into the alloy so that I should then obtain
a compound richer in alkali but containing much less peroxide of lead than in the
previous case. It is in consequence therefore of this retrograde action that I
remove the product as rapidly and uninterruptedly as possible. This retrogression
is the cause of the product not being a well defined anhydrous plumbate of soda.
After the operation there remains an excess of metallic lead still containing a
little alkali metal which is utilized in the manufacture of more alloy.
By varying the temperature of the oxidizing operation while still retaining the
same principle I may obtain at will alkaline oxide united to the heavy peroxide in
a state of fine powder by a species of sublimation. To effect this I heat the alloy
to a higher temperature (bright red) in an iron or steel vessel closed by a cover
provided with two pipe connections by one of which air is introduced. The
superheated alloy becomes ignited and the fumes composed of the combined oxides
are conducted by the other pipe into a series of large closed chambers in which
they are collected in the form of very fine powder. An apparatus for carrying out
this operation will be understood without further description. The air used may
be previously heated and it may be injected into the midst of the alloy by means
of a dip pipe for example, so as to produce a stirring effect and an energetic
oxidizing action. Many and various arrangements of apparatus based on these
principles may be devised for the purpose.
Such then are in principle the fundamental characteristics of my process. The
first result is, as before explained, the formation of an alkali compound of a
inetallic acid (plumbate, chromate, stannate, etc.). These products may either be
disposed of for use as such in other manufactures or be treated for the separation
of the acid metallic peroxide and the alkali. This separation may be effected by
different means which vary according to the nature of the compound to be
decomposed.
(1.) In order to decompose plumbate of soda, I digest it in a sufficient quantity
of water whereby the oxide of the alkali becomes hydrated and dissolves with
disengagement of heat giving up the peroxide of lead in the state of a very fine
powder resembling a precipitate. On letting rest, the peroxide powder deposits
and may be separated by decantation or filtration, and it is then washed in pure
water which serves again for the succeeding operation. The peroxide of the
heavy metal is then dried (if necessary) and the caustic soda is recovered from
its solution by evaporation as now practised, or is utilized without further
treatment. When, owing to various circumstances, the alkaline solution contains
oxide of lead in solution I separate the latter by subjecting the alkaline solution
to electrolysis which precipitates the metal upon the electrodes and thus completely
purifies the liquid. A more generally known process consists in substituting lime
for the alkali and digesting this base in a solution of the alkali salt of a metallic
acid, (chromate, stannate, etc.) then separating the solution of caustic alkali which
has been freed from the insoluble lime salt of a metallic acid which is forined and,
lastly, liberating the peroxide by saturating the lime by means of a suitable acid
such as sulphuric acid.
(2.) In order to obtain the anhydrous alkali oxide from the plumbate of soda,
I utilize the retrograde action before referred to, which occurs when the layer
of oxides is allowed to cover the alloy. By the adaptation of this special reaction
to my process, I can obtain anhydrous alkali oxide, but the peroxide is
destroyed by being reduced to heavy metal which is returned into the manufacture
of the alloy.

page_text: The operation is performed in a neutral atmosphere by placing in a closed vessel
of iron for example, alkali plumbate as poor as possible in Pb0, with an excess
of lead-sodium alloy; by heating and continually stirring the whole I effect the
reduction of the peroxide to the metallic state by the sodium of the alloy and
the formation and setting free of the adhydrous oxide of the alkali. I also
obtain the same result by mixing the alkali alloy with another reducible metallic
oxide.
In describing the fundamental operations I have supposed them to be intermittent
and capable of being performed without any special apparatus.
I will now proceed to describe the combination of my process with the
electrolytic production of alloy thus forming a continuous operation for the
production of metallic peroxides and alkali oxides upon the principle herein
described.
The apparatus which I employ in this case is illustrated by way of example in
the drawing accompanying my Provisional Specification for the purpose of clearly
shewing how my system is practically applied to an electrolytic crucible by adapting
it to my purpose, and also the mechanical arrangements for ensuring the continuity
of the manufacture.
A is an electrolytic apparatus for producing an alloy of lead and sodium by the
electrolysis of sea-salt (for example) in a state of igneous fusion, which apparatus,
considered separately, may be of any principle or system. The fused alloy is
maintained by means of a suitable supply at, say, the level a. At one side of
this crucible is applied the special apparatus B of my invention in which is
produced, and from which is extracted, the peroxide of lead united with oxide
of sodium. The apparatus B consists of a cylindro-conical open vessel communi-
cating at bottom, by means of two superposed passages C, D, with the lower part
of the electrolytic part, these channels serving to intimately connect the two parts
of the apparatus. The alloy is maintained at a sufficient height to prevent the
electrolyte passing through the channel C so that the alloy alone passes into B
which is almost completely filled, say, up to the level b, more or less.
E is a
diaphragm provided with a large opening at its centre which divides chamber B
into two superposed spaces communicating by said opening; from the diaphragın E
rises a cylindrical partition open at its upper end. F is a vertical shaft on
which are mounted (1) in the lower chamber a pallet wheel (, shewn in plan in
Figure 3, (2) in the conical portion of the upper part of the chamber curved
inclined pallets H (shewn in elevation in Figure 1 and in plan in Figure 2) wbich
scrape the conical sides of the chamber. I is an overflow spout at one side of said
chamber.
The action will be rea lily un lerstool. The electrolytic crucible being in normal
operation and charged with alloy, the shaft F is rotated so as to cause the wheel (i
to carry the bath of molten alloy in the direction of the arrows and bring it
in contact with the air and immediately the layer of oxides forms upon the
surface the blades in revolving immediately project said oxides towards the
sides and by their inclined form cause them to rise up the sides and overflow at
the spout I into a receptacle. The impoverished alloy returns through channel 1)
into A to be again enriched and returns through G to be oxidized in a continuous
manner.
Instead of the vessel B with revolving stirrers, I may employ the system of closed
vessel in which the alloy is heated to a higher temperature, into which is introduced
air to ignite the alloy, and extract the products of rapid combustion in the form of
condensable fumes, as previously described.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is -
1st. The process of peroxidizing the heavy metals herein referred to, which
process consists in alloying the metal to be peroxidized with an alkali inetal or

page_text: alkali-earth metal and oxidizing the alloy with access of air at a suitable temperature
so as to form the peroxide of the heavy metal conjointly with the alkali or alkali
earth, as specified.
2nd. In the process defined in Claim 1, effecting the continuous removal, by hand
or mechanical skimming, of the layer of oxides forined so as to prevent the reduction
of the preoxide, as specified.
3rd. The application of the principle and method of operation herein described
for at once transforming the alloys of alkali metals into hydrated or anhydrous
alkaline oxides and setting the same free by the separative operations hereinbefore
described.
4th. In the herein described process, the combination of a continuously acting
electrolytic crucible producing alloys of alkali metals and heavy metals, with the
apparatus for the simultaneous production of peroxides of the heavy metals and
alkaline oxides for the purpose of continuous manufacture
scale, as described.
Dated this noth day of August 1905
on
an industrial
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.