Improvements in the Production of Chrome Preparations.
Year: 1889

page_text: Date of Application, 16th Mar., 1889
Complete Specification Left, 16th Dec., 1889-Accepted, 15th Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Production of Chrome Preparations.
I, HERMANN ALBERT SEEGALL, manufacturer of 129, Invaliden Strasse, Berlin N.,
Germany do hereby declare the nature of this invention to be as follows:-
Up to the present the process of working substances containing Chromium in order
to obtain a soluble preparation of that element, consisted in oxydizing the material in
question, in order to obtain an Alkalichromate or Bichromate which formed the ground
work of all other Chrome preparations.
This disintegration of Chrome ores for the purpose of analyzing the same, has been
effected in the laboratorium by means of melting them together with alkalibisulphate.
This method is not however suitable for trade purposes, as, in order to secure a
complete disintegration of the ores a large excess of Bisulphate is necessary.
By my Invention I have succeeded in making this method practicable for trade
purposes by carrying on the heating in covered receptacles and conducting the gases
produced, by means of pipes leading from these receptacles to sufficiently cooled
receivers containing water. From these receivers I lead them into lime-milk and by
this means I obtain the escaping vapours for further use.
By my method herein after described-I am enabled to produce a chromic sulphate
in the form of a soluble chrome preparation from the raw materials-for wholesale
purposes which can then be worked on the other chrome preparations.
I pulverize the substance containing the chromium and heat it in covered receptacles
together with a non-neutral sulphate of a fixed alkali. During the ensuing disinte-
gration or decomposition of the raw materials a rather large quantity of vapours
containing SO, (and SO₂) escapes.
I conduct these vapours by means of pipes from the covered receptacles into cooled
condensers and obtain here the sulphuric acid, whilst I take the remaining sulphurous
acid into a receiver containing lime-milk and obtain there calcium hyposulphite.
I have further found, that the quantity of the vapours escaping during the heating
or melting, can be reduced to a minimum or possibly quite hindered, if some quantity
of a substance be introduced into the melted mass; the said substance must not melt
or decompose at a temperature of 600° (Centigrade) but only serve to make the melted
mass more pulpy.
For this purpose the oxides, hydrated oxides and non-volatile salts of the metals
of the alkaline earths and earthy metals (aluminium, iron, magnesium) may be
employed. Should it not be desired to obtain sulphuric acid as a by-product, as in
the process at first described, the decomposition of the raw materials containing
chromium will be effected and by the mixing of one of the above named substances
not only the production of chromic sulphate for trading purposes, in this manner
brought about, but also the saving of the condensing apparata effected.
1 carry out the process at first alluded to in the following manner:
100 parts of chrome ore and 400 parts of sodium bisulphate are ground very fine
and thoroughly mixed. The mixture is then heated to 600° (Centigrade) for a space
of 2-2 hours by which means the chrome ore will be almost completely decomposed,
and the amount of sulphuric acid corresponding to 200 parts of bisulphate will be
received in the condensers. The gases (SO,) not condensed in the condensing apparata
will be arrested by the lime-milk. The melted mass is then cooled up and lixiviated
with water.
The second method alluded to is carried out in the following manner:
100 parts of chrome ore, 200 parts of sodium bisulphate and 50 parts of sulphate
of barium are finely pulverized and thoroughly mixed. The mixture is then heated
to-a-temperature of 600° (Centigrade) for the period of '2-24 hours. The quantity

page_text: of vapours, produced by this method, is so insignificant, that they may be allowed
to escape.
After the melting has taken place, the mass will be removed from the
melting boiler whilst warm and lixiviated with water.
From the chrome sulphate-which is contained in combination with other sulphates in
the watery solution-resulting from both methods-it is now easily possible to obtain the
bydrated oxide of chromium through precipitation by means of the well known reagents
(such as caustic alkalis, alkaline carbonates, magnesia &c.) when the hydrated oxide of
chromium forms a porous easily oxidable mass,
This hydrated oxide of chromium is certainly in the most cases impurified by the
presence of hydrated oxide of aluminium and hydrated oxide of iron, from which it
can however be easily separated (for instance by washing.
This hydrated oxide of chromium forms a much better essential element for the
production of the other chrome preparations, than the alkalibichromate used for the
same purpose, up to the present. For the production of chrome salts it is not necessary
to make any reduction as the hydrated oxide of chromium combines directly with
acids to form salts of chromium.
The oxydation for the formation of chromates can be conveniently carried out, since
the hydrated oxide of chromium combines directly with bases forming the corresponding
chromates. Lastly, the oxygen in cooperation with the impurifying hydrated oxides
has an advantageous effect, whilst in the methods of carrying out the oxydation, up to
the present in use, impurities had a reducing effect on the melting mass.
By working the oxidation according to my method, not only a saving of time is
effected, but also less firing material is required, the apparata required are simpler
and in consequence cheaper, the process is less troublesome and a more complete
oxydation takes place than in the processes up to the present in use.
Dated Berlin. this 13th day of March 1889
HERMANN ALBERT SEEGALL.
By A. Kuhut & R. Deissler,
38, Alexander Strasse, Berlin C., Germany, Agents for Applicant.
COMPLETE SPECIFICATION.
Improvements in the Production of Chrome Preparations.
J, HERMANN ALBERT SEEGALL, of 129 Invaliden Street Berlin, N. Germany,
manufacturer, 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 :-
Up to the present the process of working substances containing chromium in order
to obtain a soluble preparation of that element consisted in oxydizing the material in
question in order to obtain an alkali chromate or bichromate, which formed the
groundwork of all other chrome preparations. The disintegration of chrome ores for
the purpose of analysing the same has been effected in the laboratory by means of
melting them together with alkali bisulphate. This method is not, however, suitable
for trade purposes, since in order to secure a complete disintegration of the ores a
large excess of bisulphate is necessary, whereby through the developement of sulphuric-
acid vapors the lungs of the workmen are injuriously affected and only an imperfect
utilization of the bisulphate is attained.
I have discovered that three important points in the process must be taken into
account and carried out before the same can be employed with advantage for trade
purposes. The first of these three points consists in holding the chrome materials in
suspension in melted alkali during the beating of the same, in order to impart to it a
large surface of contact for the escaping sulphuric acid. The second of these important
points is the regaining of the sulphuric-acid vapors (having escaped without having taken
part in the reaction) through condensation. The third of these important points is
the stopping of the process at the right time, i.e. before or when vapours of sulphurous
acid (SO) escape, in order to prevent the disintegration of the sulphates of chromium,

page_text: of iron etc. formed and their retro-formation into oxides of metals. These three points
in the disintegration of the raw materials containing chrome combine to make my
process capable of being used with advantage for industrial purposes.
By my method, hereinafter described, I am enabled to obtain a chromic sulphate in
the form of a soluble chrome preparation direct from the raw materials, suitable for
industrial purposes, which can then be worked on the other chrome preparations.
I pulverize the substance containing the chromium and heat it in receptacles
provided with mechanical stirring apparatus, together with an acid sulphate of a fixed
alkali. During the ensuing disintegration or decomposition of the raw materials,
which is very complete in consequence of the thorough mixing of the ore with the
sulphuric acid produced, a rather large quantity of vapors containing SO, (and SO,)
escapes. I conduct these vapors by means of pipes into cooled condensers, where I
obtain the sulphuric acid, while I take the remaining sulphurous acid into a receiver
containing lime-milk and obtain there calcium sulphite. The holding of the raw
material in suspension during the heating, which is throughout necessary for the
process, may not only be attained by means of stirring apparatus, but also by a shaking
apparatus or revolving furnace.
In the process just described the only disadvantages are the necessity of carrying
on the heating in covered receptacles, of condensing the escaping gases, and of having
to work with a mechanical stirring arrangement of some sort.
I have further found that the quantity of the vapors produced during the heating
or melting may be reduced to a minimum or entirely prevented if some quantity of a
substance be introduced into the melted mass. The said substance must not melt or
decompose at a temperature of 600° centigrade, but only serve to make the melted
mass more pulpy. The explanation of this result is the following:
Since the bisulphates of fixed alkalis melt to a pretty thin liquid at 197° centigrade,
the powdered ore sinks to the bottom in the liquid alkali bisulphate during the
process on account of its heavier specific weight. In consequence the surface of
contact of the two masses forms the only point where the bisulphato can exercise its
influence on the ore. At about 340° centigrade the bisulphate
pyrosulphate and water,
converted into
The sulphuric acid which becomes free can of course only work upon the ore on
coming into contact with the same. It cannot, however, come into contact with the
ore if the same is lying on the bottom of the melting pot and the sulphuric acid
steaming away from the upper surface of the contents of the pot. It is here that the
advantage becomes apparent of intermixing a substance which neither melts nor
decomposes nor precipitates at a temperature of 600° centigrade. The melted mass is
no longer so thin and the powdered ore is no longer able to sink to the bottom, but is
held in close contact with the melted bisulphate, and is in consequence subjected to
the influence of the sulphuric acid released from the same. When the sulphuric acid
has once combined, it will no longer escape at the temperature mentioned, and only
those parts of the bisulphate which are lying right on the surface will give off
their SO. It is for this reason advisable to add a certain amount of the refractory
substance to the melting mass. The gases can then with difficulty make their way
through the pulpy mass in order to escape.
There are certainly some materials containing chromium (chrome slags) which
when melted with bisulphate immediately cause the mass to assume a thick pulpy
nature; but they do not remain suspended in the same, and in consequence require
the aid of a mechanical stirring apparatus. If I takes, specific gravity of the
substance added, P absolute weight of the substance added, s, specific gravity of

page_text: G s¹
the mixture set, G weight of the mixture set or melted; and equal the quotient of
the volume of the mixture set, by the volume of the melted mixture, then is P =
and a= If equal one, no addition is necessary.
32.
=
All substances which do not melt or decompose at the temperature necessary for
the process viz., 600° centigrade may be used for adding to the mixture, particularly
the oxides, hydrated oxides, non volatile salts of the metals of the alkaline earths; and
of the earthy metals and silicic acid. In case it is not required to gain sulphuric
acid as a by-product, as in the process at first described, the condensers and stirring
apparatus may be dispensed with. When mixing any of the substances just
mentioned to the melting mass, the decomposition of the materials containing
chromium will be attained in the lastly-described manner.
I perform the process at first described in the following manner: One hundred
parts of chrome ore and four hundred parts of sodium bisulphate are ground up very
fine and thoroughly mixed. The mixture is then heated in covered receptacles
provided with a stirring apparatus to 600° centigrade for the space of about two to'
two and one half hours by which means the chrome ore, since it is held in suspension,
will be almost entirely decomposed, and the amount of sulphuric acid corresponding
to two hundred paris of bisulphate will be received in the condensers. The gases (SO₂)
not condensed in the condensing apparatus will be arrested by the lime-milk. The
melted mass is then cooled up and lixiviated with water.
I perform the second method by finely powdering and mixing one hundred parts'
of chrome ore with two hundred parts of sodium bisulphate and fifty parts of barium
sulphate and then heating the mixture to a temperature of 600° centigrade for about
two to two and one-half hours. The quantity of vapors produced by this method is
so insignificant that they may be allowed to escape. After the melting has taken place
If barium
the mass will be removed from the melting-pot and lixiviated with water.
sulphate be not used as an addition, the minimum amount of the mass to be added
may be obtained from the equation for P. In any case a material must be chosen,
which at 600° centigrade does not combine with the sulphuric acid set free: Should
a material be employed, for this purpose, which does combine with the sulphuric acid
which is released, it is then always necessary to add bisulphate enough to satiate the
requirements of the material added and then be sufficient to decompose the materials
containing the chrome. Accordinglys will in this case represent the specific gravity,
of the combination of the material added with sulphuric acid.
From the chrome sulphate which is contained in combination with other sulphates
in the watery solution resulting, from both methods it is now easily possible to obtain
the hydrated oxide of chromium through precipitation by means of the well known
re-agents, (such as caustic alkalies) alkaline carbonates, magenisa etc. when the
hydrated oxide of chromium forms a porous easily-oxidizable mass. This hydrated
oxide of chromium is certainly in the most cases impurified by the presence of
bydrated oxide of aluminium and hydrated oxide of iron, from which it can, however,
easily, be separated, (for instance, by washing). This hydrated oxide of chromium
forms a much better essential element for producing the other chroine- preparations
than the alkali bichromate used up to the present in the industry for the same
purpose.
For forming chrome salts from this hydrated oxide of chromium it is not necessary
to make any reduction, as the hydrated oxide of chromium combines directly with
acids to form salts of chromium. The oxidation for the formation of chromates can
also be conveniently carried out, since the hydrated oxide of chromium combines
In the latter case the
directly with bases forming the corresponding chromates.
oxygen in co-operation with the impurifying hydrated oxides produces an advantageous
effect, while in the methods of carrying ont the oxidation up to the present in use
impurities had a reducing effect on the melting mass.
In working the oxidation according to my method not only a saving of time is
effected, but also less firing material is required. It may be carried out much more

page_text: easily and with far simpler and less expensive apparatus. Lastly, a much more
complete using up of the materials employed is attained than in those proceses in use
up to the present.
In the following claims I mean by the term "acid sulphates of any fixed alkali "
not only the combination RH SO, but all sulphates of fixed alkalies which with regard
to the combination R, SO, contain an excess of sulphuric acid.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed. I declare that what I
claim is :
1. The process of manufacturing chromic or chromous sulphates from materials
containing chrome by heating the said substances in covered receptacles with the acid
sulphates of any fixed alkali, and holding the materials containing chrome continually
in suspension in the melting mass by mechanical agitation, for the purpose and in the
manner substantially as described.
2. The process of manufacturing chromic or chromous sulphates from materials
containing chrome by heating the said substances in covered receptacles with the
acid sulphates of any fixed alkali, and holding the materials containing chrome
continually in suspension in the melting mass by mechanical agitation, and then
condensing the escaping vapors and regaining the sulphuric acid which has not
entered into the reaction, substantially as herein described.
3. The process of manufacturing chromic or chromous sulphates from materials
containing chrome by heating the substances with the acid sulphates of any fixed
alkali, and with a refractory mass which does not decompose or melt under 600° in
such a manner that sulphuric acid (SO,) is liberated and decomposes the materials
containing chrome, substantially as described.
4. The process of manufacturing chromic or chromous sulphates from materials
containing chrome by heating the said substances with the acid sulphates of any fixed
alkali and stopping the process in the right time, before or when sulphurous
vapors (SO) escape.
Dated Berlin. this 13th day of December 1880
HERMANN ALBERT SEEGALL.
By A. Kuhnt & R. Deissler,
38, Alexander Strasse, Berlin C., Germany.