IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF CONCENTRATED SULPHURIC ACID AND OTHER MINERAL ACIDS
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Gerard Wenzeslaus von Nawrocki
at the Office of the Commissioners of Patents on the 15th November 1876.
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and
G. W. v. Nawrocki, of Berlin, in the German Empire. "IMPROVEMENTS IN
APPARATUS FOR THE MANUFACTURE OF CONCENTRATED SULPHURIC ACID AND
OTHER MINERAL ACIDS." A communication from Ludwig Brumleu, of Berlin, in
the German Empire.
1
The apparatus consists mainly of a burner where brimstone or any other sulphur
containing mineral are burned, of several vessels or chambers of any size or shape
connected with the burner by means of pipes, and of an air pump or blower or other
similar instrument.
The burner may be the same as used in the manufacture of sulphuric acid for the
purpose of the burning of brimstone or other minerals containing sulphur. At a
suitable distance above the burning brimstone is a vessel of iron or other material
placed so that it is reached by the flame or heat of the burning material and its
contents become heated by the same. This vessel is filled with either nitric acid or
any other salts of nitre, with a due proportion of sulphuric acid, so that nitric acid
is produced. At the side a small pipe of iron or other material is entered through
the wall of the burner above the burning material, through which pipe a small
stream of steam can be blown into the inside of the burner just above the burning
materials. From this burner some distance above the burning brimstone a pipe of
a pretty large dimension is led through the back wall of the burner till within a
short distance from the bottom of the first vessel or chamber, being passed through
the top of this chamber. A damper is placed so that this tube can be closed inside
the-burner-as-occasion-requires.
1
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The first vessel or chamber inay be of any shape, the size being regulated in pro-
portion to the quantity of sulphur to be burned and the size of the burner. By
preference this chamber is constructed of brickwork, narrow, low, and long, for

page_text: reasons which will appear afterwards. It may be 12-20 feet long, 4-5 feet wide,
and 2 feet high, inside clear of the wall. The sole of the chamber must be of cast
iron plates with a fire-place under it to heat the contents of the chamber.
According to the nature of the acid to be made, the inside of this chamber must be
lined with lead as far as up to the doors, or it may remain free from any lining so
that the sides and top are coated with cement and the sole of iron. This chamber
is divided in different compartments by either glass plates or iron plates, according
to requirement, cased in sheet lead, these divisions reaching only from the top of the
chamber to about its middle, leaving the lower half of the chamber undivided. Each
of these divided compartments is on one side provided with an opening so arranged
that it can easily be closed by a sliding door of glass or otherwise. These slides or
shutters must have a small hole just barely large enough to pass the iron handle of
a rake through for the purpose of stirring up or raking the contents of the chamber
without opening the doors. Besides the pipe or tube connecting the chamber with
the burner, there is another pipe carried through the top of the chamber to within a
few inches of the sole of the chamber; this pipe is connected with an apparatus
where air is heated in any way it may suit best, and also provided with a damper.
This first chamber is connected with a second chamber of about the same dimension
and size by a pipe coming out from the top of the first chamber, going through the
top of the second chamber to within a short distance from the sole or bottom of the
same. This chamber is also divided into several compartments with this difference,
that the partitions of the second chamber go from top to bottom, forming thereby
several separated smaller compartments, all connected thro' pipes going from the
upper part of the first partition to within a short distance of the sole or bottom of
the next, and so forth from the second to the third, and so on to the last compart-
ment. This second chamber must be placed so much higher than the first one as to
permit its liquid contents to run through the intermediate compartments into the
first chamber. For this purpose all the chambers or compartments are connected by
pipes of lead, glass, or any other suitable material, and these pipes are provided with
cocks so that they can be opened or shut as the case may require; these pipes going
from the bottom of one partition to the bottom of the next one, the contents of all
the partitions can be run into the first chamber. These small compartments require
no lining but only a coating of cement; openings or doors are not absolutely re-
quired, but may be useful for the purpose of inspecting the chamber and for repairs,
and have to be so arranged that they can be luted air-tight. From the top of the
last compartment a pipe connects the whole chamber system with an air pump,
blower, or other instrument suitable for sucking the air from the chamber.
When in this way the apparatus is completed, the working of the same is con-
ducted in the following manner :-If the apparatus is used for making sulphuric
acid, the chambers are kept dry or empty, that is, no water is put in. The brim-
stone in the burner is then ignited and when it is fairly burning and nitric acid
provided in the vessel for that purpose, the air pump.or blower is put in motion,
and the steam pipe opened to let in a stream of steam.
By the suction of the air pump or blower the vapours of the burning brimstone or
other sulphur-containing material being sulphurous acid, the steam and the vapour
of the nitric acid will be drawn through the pipe or tube provided for that purpose
into the first chamber, and there, the chamber being kept cold, condensing, drop
down in a liquid form as sulphuric acid. To forward this dropping down, and to
prevent a too quick passage through the whole chamber system, those half partitions
are constructed as already described.
In the first chamber the strongest acid is produced, whereas the mostly exhausted
vapors in passing through the smaller chambers have only a very weak acid, in
small quantities, and finally pass out through the blower or air pump completely
exhausted. During this stage of the proceedings the cocks of the connecting pipes
are kept open so that all the weak acid which is precipitated in the compartiments
may run back into the first chamber.

page_text: The velocity of the air pump or the size of the same must be regulated so that all
the sulphurous acid, steam, &c., is drawn from the burner into the chamber. If the
pump is too small or is worked too slowly, sulphurous acid will escape through the
door or air holes of the burner, if too large or worked too quickly the draught will
be too quick and the vapors hurried too quickly through the chambers and not be able
to discharge all the sulphuric acid which is contained in them. The quantity of steam
can be regulated in such a way that the acid in the chamber is about 40 degrees
Beaumé strong to avoid useless condensing afterwards. When in this way the first
chamber is filled about half or up to the door or as high as the lining of lead will
admit, the act of concentrating begins and is continued till the acid has acquired the
required strength of 66 degrees Beaumé or more. To obtain this object fire is made
under the first chamber, the tube connected with the burner closed, and instead of that
the tube connected with the hot-air furnace opened, and the cocks of the pipes closed
which connect the different chambers. The blower or air pump now put in motion
draws the hot air quite through the weak and hot acid, and in so doing dissolves water
and some acid in its passage which is carried off with the air through all the small
chambers where, these being kept cold, the weak acid will be condensed and collect
at the bottom of the chamber. The passing of hot air through the hot acid will not
alone be the means of concentrating the acid by the passage of the air through the
acid; it will be kept in a state of motion just as is produced by the boiling of a
liquid, and a strong evaporation of water and acid takes place, which by the
draught of the blower is drawn into the small cold chambers and there condensed.
As soon as the required strength is obtained the acid may be drawn off by a syphon
or a pipe left for this purpose in the chamber into a cooling vessel, or left in the
apparatus to cool there, just as it may be convenient. To keep up a perpetual
process each burner ought to connect with two sets of chambers, so that one makes
weak acid during the same time that the other concentrates.
For the purpose of manufacturing chloride of lime or bleaching powder, the
required ingredients are brought into the first chamber and the process carried on
the same way as for making sulphuric acid; the sulphuric acid formed then will,
being condensed, drop down on the ingredients, decompose them, and make the
chlor gas free, which in passing through the chambers will there deposit the
moisture which it contained, and may then by the air pump or blower be conveyed
through pipes to the rooms where lime is spread out to take the gas up and form
bleaching powders.
In the beginning of the process no fire is required until the contents of the
chambers are nearly decomposed, when heat has to be applied to forward the process
and drive off all the gas by fire under the chamber as well as by the influx of hot
air. When all the salts are decomposed the influx of sulphuric acid from the burner
has to be stopped, and the fire as well as the influx of hot air continued till all or
nearly all the chlor gas is driven off. During all the time the contents of the
chamber have to be stirred up and raked up by means of iron rakes, the handles of
which are passed through the small holes left for this purpose in the doors. Of
course the doors have to be made tight as much as possible and luted to prevent the
escape of gas and the entering of cold air.
To decompose salt for the purpose of getting the sulphate of soda and hydro-
chloric acid, the first chamber is filled with salt and the small chamber with water
up to the door of the chamber, and then the process is carried on as described by
sulphuric acid. The water in the small chambers will take up the gas which is .
created by the decomposition of the salt, and form thereby hydrochloric acid,
whereas the salt is turned into sulphate of soda. When all or nearly all the salt is
decomposed fire is made under the chamber and even with the assistance of hot air
the whole mass is raked and-stirred up by the rakes till all the gas is driven off just
as is always done now in making this article.
For works where much carbonic acid is used for the purpose of making bi-
carbonate of soda, the last chamber may be provided with a stirrer or agitator and

page_text: then filled with water and chalk or marble dust, the stirrer being kept in motion
and the gas being drawn through the chalk will be decomposed to muriate of lime,
while carbonic acid getting free may be forced by the blower or air pump into the
room where soda is arranged in the usual way to be transformed into bicarbonate
of soda.