Method of Producing Anhydrous Sulphuric Acid and its Mono- hydrate, and of Utilizing for this Purpose the Acid Residues of Petroleum Production and other, as also Sulphates of all Metals.
Year: 1887

page_text: Date of Application, 19th Sept., 1887
Complete Left. 8th June, 1888
Complete Accepted, 13th July, 1888
Method of Producing Anhydrous Sulphuric Acid and its Mono-
hydrate, and of Utilizing for this Purpose the Acid Residues of
Petroleum Production and other, as also Sulphates of all Metals.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communication
to me from abroad by Victor Ragosine, Secretary of Government, and Paul
Dvorkovitch, Master of Pharmacy, both of Moscow, in the Empire of Russia,) do
hereby declare the nature of this invention to be as follows:
-
In the Petroleum production, by the generally employed method of refining of
petroleum and its products by sulphuric acid, there are accumulated enormous
quantities of acid residues, containing up to 90% of free sulphuric acid.
This invention relates to a method of utilizing these residues for producing
anhydrous and fuming sulphuric acid, and its mono-hydrate. For this purpose, the
acid residues are transformed first into sulplates, and thereupon these sulphates are
used as a material for producing anhydrous sulphuric acid &c. by the new method
hereafter described.
To obtain sulphates, any metallic oxides, especially iron oxide, may be used. Thus,
for instance, by adding to the acid residues iron ochre (caput mortuum) somewhat in
excess a strong reaction is caused, the liquid becomes strongly heated and not only the
free acid, but also the sulphates enter into combination with the ochre.
The resulting compound of sulphate of iron and resinous matters can be treated
with light petroleum oils whereby all resinous parts are dissolved and the remaining
salts, after drying, can be immediately employed for producing anhydrous sulphuric
acid &c. as described below.
Dissolving the resinous matters by light petroleum oils can also be dispensed with,
and the compound of sulphate of iron and rosins, after evaporating the water by
heating, can be placed directly into a furnace for producing anhydrous sulphuric
acid &c. as described below. The resinous parts can thereupon be burned out and the
remaining salts used again for neutralizing the acid residues.
It is evident that this method permits also utilizing acid residues of all other
productions, besides that of petroleum.

page_text: The new method of producing anhydrous sulphuric acid &c. is based on the following
considerations.
By numerous experiments and observations it has been found: 1-that in distilling
sulphates in retorts, the main impediment to obtaining anhydrous acid consists in
the great specific weight of the anhydrous acid vapours, which after separating from
the salts lie motionless on top of the layer of salts; 2-that heating throughout thick
layers of salts, which are bad conductors of heat, requires considerable and useless
waste of fuel; 3-that by heating sulphate of iron, one part of anhydrous sulphuric
acid is very easily separated at a temperature not exceeding 300° C, whilst the two
remaining parts of anhydrous acid require for their separating a considerable increase
of heat, wherewith part of the anhydrous sulphuric acid is decomposed into sulphurous
acid and oxygen, which is likewise the case with other sulphates at a high temperature.
These observations prove that for successful production of anhydrous sulphuric acid
from sulphates, it is necessary, first of all, to remove the anhydrous vapours from the
retorts or apparatus where those vapours are developed, either by blowing air into
the said retorts or apparatus, or by connecting the latter with a chimney. Besides, as
one part of anhydrous acid separates from the sulphates at a comparatively low
temperature, the costly and troublesome retorts can be replaced by a common furnace.
In practice, the operator may proceed as follows: On 160 parts of ochre (caput
mortuum) are poured 322 parts of ordinary sulphuric acid or a corresponding quantity
of acid residues; the compound is stirred, and as its temperature is raised to 160° C.,
the greatest part of water is evaporated. The compound must be somewhat cooled or
the whole operation carried on slowly, because already at 150° the anhydrous acid
begins to separate. The solid mass thus obtained is first crushed and thereupon placed
in the furnace, on the sole of which it is disposed in a thin layer, not allowing the
temperature of the furnace to exceed 300° C.
It is easily understood that, if for obtaining anhydrous acid, other sulphates are
employed, the furnace must be brought to the temperature, in which the chosen
sulphates are decomposed.
The furnace ought to have, by preference, a low vault which, narrowing, turns into
a pipe, which, for instance, can be of clay, and is connected with the receivers.
By blowing air (previously dried by letting it pass through chambers containing
sulphuric acid and lime) or by drawing it out by means of a chimney placed behind
the receivers, the anhydrous vapours developed are continually driven into the
receivers, where they condenso to solid anhydrite by cooling, or are caught in
concentrated sulphuric acid, producing fuming sulphuric acid of the required
strength.
The sulphate employed must from time to time be stirred in the furnace during its
decomposition and, at the same time, it can be gradually removed from the less hot
to the hottest part (heated to 350° C.) of the furnace, where the salt, having lost
one part of anhydrite, can be withdrawn from the furnace, whilst fresh salt is placed
in the less hot part of the furnace. Thus the process of decomposition can be continued
without interruption.
After extracting one part of anhydrite from 400 parts of sulphate of iron, are
left 320 parts salt, to which are added, in stirring, 106 parts sulphuric acid or a
corresponding quantity of acid residues. The compound is dried, to remove the water,
and thereupon placed again in the furnace.
The furnace for producing anhydrous sulphuric acid is constructed with a fireplace
underneath, in order to prevent immediate contact of the sulphate under treatinent
with the products of combustion of the fuel.
It is obvious, that all other details of the construction of the furnace may be varied
at will.
The chief advantages of the method consists in the following:
1. The whole of anhydrous acid of the employed sulphuric acid is obtained in the
form of pure anhydrous acid.
2. The decomposition is going on without interruption.
3. The distilling retorts are completely dispensed with.

page_text: 4. It requires little expense for fuel, as the decomposition takes place at low
temperatures and no heat is lost in cooling the furnace after each operation.
5. The evaporation of water at the following addition of sulphuric acid to the salt
which already yielded one part of anhydrous acid, can be performed by the waste
heat of the furnace.
As an example of the economy to be realized by this method it may be mentioned
that a furnace with a sole of 0.45 of a square meter, can, by this method, produce
in 48 hours 384 kilograms anhydrous acid, for which (for instance by Stak's method)
would be required about 2000 retorts.

page_text: Method of Producing Anhydrous Sulphuric Acid and its Mono-
hydrate, and of Utilizing for this Purpose the Acid Residues of
Petroleum Production and other, as also Sulphates of all Metals.
to
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communication
me from abroad by Victor Ragosine, Secretary of Government, and Paul
Dvorkovitch, Master of Pharmacy, both of Moscow, in the Empire of Russia,) 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
In the petroleum production, by the generally employed method of refining of
petroleum and its products by sulphuric acid, there are accumulated enormous
quantities of acid residues, containing up to 90% of free sulphuric acid.
This invention relates to a method of utilizing these residues for producing
anhydrous and fuming sulphuric acid, and its mono-hydrate. For this purpose the
acid residues are transformed first into sulphates, and thereupon these sulphates are
used as a material for producing anhydrous sulphuric acid &c. by the new method
hereafter described.
To obtain sulphates, any metallic oxides, especially iron oxide, may be used. Thus,
for instance, by adding to the acid residues iron ochre (caput mortuum) somewhat in
excess a strong reaction is caused, the liquid becomes strongly heated and not only the
free acid, but also the sulphates enter into combination with the ochre.
The resulting compound of sulphate of iron and resinous matters can be treated
with light petroleum oils whereby all resinous parts are dissolved and the remaining
salts, after drying, can be immediately employed for producing anhydrous sulphuric
acid &c. as described below.
Dissolving the resinous matters by light petroleum oils can also be dispensed with,
and the compound of sulphate of iron and rosins, after evaporating the water by heat-
ing, can be placed directly into a furnace for producing anhydrous sulphuric acid &c.
as described below. The resinous parts can thereupon be burned out and the remain-
ing salts used again for neutralizing the acid residues.
It is evident that this method permits also utilizing acid residues of all other
productions, besides that of petroleum.
The new method of producing anhydrous sulphuric acid &c. is based on the follow-
ing considerations:-
By numerous experiments and observations it has been found: 1-that in distilling
sulphates in retorts, the main impediment to obtaining anhydrous acid consists in the
great specific weight of the anhydrous acid vapours, which after separating from the
salts lie motionless on top of the layer of salts; 2-that heating throughout thick
layers of salts, which are bad conductors of heat, requires considerable and useless
waste of fuel; 3-that by heating sulphate of iron, one part of anhydrous sulphuric acid

page_text: is very easily separated at a temperature not exceeding 300° C., whilst the two remain-
ing parts of anhydrous acid require for their separating a considerable increase of
heat, wherewith part of the anhydrous sulphuric acid is decomposed into sulphuric
acid and oxygen, which is likewise the case with other sulphates at a high tempera-
ture. These observations prove that for successful production of anhydrous sulphuric
acid from sulphates, it is necessary, first of all, to remove the anhydrous vapours from
the retorts or apparatus where those vapours are developed, either by blowing air
into the said retorts or apparatus, or by connecting the latter with a chimney. Besides,
as one part of anhydrous acid separates from the sulphates at a comparatively low
temperature, the costly and troublesome retorts can be replaced by a common
furnace.
In practice the operator may proceed as follows:
On 160 parts of ochre (caput mortuum) are poured 322 parts of ordinary sulphuric
acid or a corresponding quantity of acid residues; the compound is stirred, and as its
temperature is raised to 160° C. the greatest part of water is evaporated.
The com-
pound must be somewhat cooled or the whole operation carried on slowly, because
already at 150° the anhydrous acid begins to separate. The solid mass thus obtained
is first crushed and thereupon placed in the furnace, on the sole of which it is disposed
in a thin layer, not allowing the temperature of the furnace to exceed 300 C.
It is easily understood that, if for obtaining anhydrous acid, other sulphates are
employed, the furnace must be brought to the temperature, in which the chosen
sulphates are decomposed.
The furnace ought to have, by preference, a low vault which, narrowing, turns into
a pipe, which, for instance, can be of clay, and is connected with the receivers. .
By blowing air (previously dried by letting it pass through chambers containing
sulphuric acid and lime) or by drawing it out by means of a chimney placed behind
the receivers, the anhydrous vapours developed are continually driven into the
receivers, where they condense to solid anhydrite by cooling, or are caught in
concentrated sulphuric acid, producing fuming sulphuric acid of the required
strength.
The sulphate employed must from time to time be stirred in the furnace.during its
decomposition and, at the same time, it can be gradually removed from the less hot
to the hottest part (heated to 350° C.) of the furnace, where the salt, having lost one
pari of anhydrite, can be withdrawn from the furnace, whilst fresh salt is placed in the
less hot part of the furnace. Thus the process of decomposition can be continued
without interruption.
After extracting one part of anhydrite from 400 parts of sulphate of iron, are left
320 parts salt, to which are added, in stirring, 106 parts sulphuric acid or a correspond-
ing quantity of acid residues. The compound is dried, to remove the water, and
thereupon placed again in the furnace.
The furnace for producing anhydrous sulphuric acid is constructed with a fire-place
underneath, in order to prevent immediate contact of the sulphate under treatinent
with the products of combustion of the fuel.
It is obvious, that all other details of the construction of the furnace may be varied
at will.
The chief advantages of the method consist in the following:
1. The whole of anhydrous acid of the employed sulphuric acid is obtained in the
form of pure anhydrous acid.
2. The decomposition is going on without interruption.
3. The distilling-retorts are completely dispensed with.
4. It requires little expense for fuel, as the decomposition takes place at low
temperatures and no heat is lost in cooling the furnace after each operation.
5. The evaporation of water at the following addition of sulphuric acid to the salt
which already yielded one part of anhydrous acid, can be performed by the waste heat
of the furnace.
As an example of the economy to be realized by this method it may be mentioned
that a furnace with a sole of 0.45 of a square meter can, by this method, produce in

page_text: 48 hours 384 kilograms anhydrous acid, for which (for instance by Stak's method)
would be required about 2000 retorts.
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 :-
-
The above described method of producing anhydrous or fuming-sulphuric acid or its
mono-hydrate from common (market) sulphuric acid or acid residues of the petroleum
and other productions, by means of adding to the same sulphates of metals, by
preference of iron, and heating the compounds obtained, or directly from any sulphates,
without rising retorts, directly on the sole of a furnace or on metallic plates or pans,
with application of artificial or natural draught of air, it being indifferent, whether
the air or other gas is blown in by blast machines or drawn off by a conveniently
placed draught chimney.
CARPMAEL & Co.,
Agents for the Applicant.