IMPROVEMENTS IN THE OBTAINMENT OF SULPHATE OF AMMONIA FROM AMMONIACAL LIQUORS, AND IN THE APPARATUS EMPLOYED THEREFOR, THE SAID IMPROVEMENTS BEING ALSO APPLICABLE FOR THE OBTAINMENT OF CYANIDE AND SULPHO-CYANIDE OF AMMONIUM
Year: 1878

page_text: LETTERS PATENT to Peter Stuart Brown, of Carrickfergus, in the County of
Antrim, Ireland, Manufacturing Chemist, for the Invention of
"IMPROVEMENTS
IN THE OBTAINMENT OF SULPHATE OF AMMONIA FROM AMMONIACAL LIQUORS,
AND IN THE APPARATUS EMPLOYED THEREFOR, THE SAID IMPROVEMENTS BEING
ALSO APPLICABLE FOR THE OBTAINMENT OF CYANIDE AND SULPHO-CYANIDE OF
AMMONIUM."
Sealed the 23rd August 1878, and dated the 27th February 1878.
PROVISIONAL SPECIFICATION left by the said Peter Stuart Brown at the
Office of the Commissioners of Patents on the 27th February 1878.
PETER STUART BROWN, of Carrickfergus, in the County of Antrim, Ireland,
Manufacturing Chemist. "IMPROVEMENTS IN THE OBTAINMENT OF SULPHATE OF
AMMONIA FROM AMMONIACAL LIQUORS, AND IN THE APPARATUS EMPLOYED THEREFOR,
THE SAID IMPROVEMENTS BEING ALSO APPLICABLE FOR THE OBTAINMENT OF CYANIDE
AND SULPHO-CYANIDE OF AMMONIUM."
This Invention, which relates to improvements in obtaining sulphate of ammonia
from ammoniacal liquors, consists as follows:-I take the ammoniacal liquor, to
which I add sulphuric acid, in quantity, however, insufficient to render it acid, that
is to say, the acid may be sufficient to neutralise the alkali of the liquor, or it may
be less than sufficient for that, in which case the liquor is slightly alkaline.
The liquor, after the sulphuric acid is thus added to it, is placed in a vessel, which
may be of iron or other suitable material, and to this vessel I apply heat, which
drives off the water as steam, and when concentrated far enough allows the ammonia
to crystallize out. During the time of evaporation the tendency of the concen-
trating liquor is to become acid, and this tendency I counteract by adding alkali
thereto from time to time. Any alkali will answer for this purpose, but I have
found the crystals of carbonate of soda to give good results.
An arrangement of apparatus which I find well suited for the purpose of prac-

page_text: tically working my Invention consists of a vessel in which the acid is added to the
ammoniacal liquor. From this vessel the liquor is discharged into a boiler or other
like vessel, wherein it is partly concentrated, and from this it is led successively
through a series of concentrating vessels, by which it is gradually increased in
density.
In the last vessel of the series the crystals of sulphate of ammonia are thrown
down in the boiling liquor, and are obtained by being dipped out therefrom and
placed on a drainer in the ordinary manner. In arranging the vessels for operating
my process I cause the more intense heat of the fires to act upon the upper parts
of the vessels, and the less intense heat to act upon their bottoins.
The cyanides and sulpho-cyanides of ammonium may also be obtained from ammo-
niacal liquors when treated in the manner I have herein-before described, that is to
say, the cyanide or sulpho-cyanide being highly soluble will collect in the last vessel
of the series up to a considerable proportion before being precipitated. So soon as
they begin to precipitate with the sulphate of ammonia I disconnect that vessel
from the series, in which case the preceding vessel becomes the last of the series,
thus preventing the discharge into the disconnected vessel of more concentrated
liquor. I then evaporate the liquor in this vessel, from which the cyanides and
sulpho-cyanides crystallize out.
In place of conducting my process in a continuous way, as herein-before described,
it may be carried on in a single vessel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Peter Stuart Brown in the Great Seal Patent Office on the 27th
August 1878.
PETER STUART BROWN, of Carrickfergus, in the County of Antrim, Ireland, Manu-
facturing Chemist. "IMPROVEMENTS IN THE OBTAINMENT OF SULPHATE or
AMMONIA FROM AMMONIACAL LIQUORS, AND IN THE APPARATUS EMPLOYED THEREFOR,
THE SAID IMPROVEMENTS BEING ALSO APPLICABLE FOR THE OBTAINMENT OF CYANIDE
AND SULPHO-CYANIDE OF AMMONIUM."
According to my said Invention I take ammoniacal liquor (such as the waste
ammoniacal liquor from gas works) to which I add some sulphuric acid, in quan-
tity insufficient however to render it acid, that is to say, the acid may be sufficient
to neutralize the alkali of the liquor, or it may be less than sufficient for that, in
which case the liquor is slightly alkaline.
The liquor after the sulphuric acid is thus added to it is conducted into a vessel
or a series of vessels, which may be of iron or of other suitable material, and to the
said vessel or series of vessels I apply heat which drives off the water as steam.
When the liquor is evaporated or concentrated far enough the ammonia crystallizes
out. During the time of evaporation the tendency of the concentrating liquor is to
become acid, and this tendency I counteract by adding alkali thereto from time to
time.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, reference being had to the
accompanying Drawings, and to the letters and figures marked thereon, that is to
say,―
Figure 1 represents in plan (partly in section, on the line 1, 2, Figure 2), and
Figure 2 in sectional elevation, an arrangement of apparatus which I have found
to answer well in the process of obtaining sulphate of ammonia according to my
Invention.
Ammoniacal liquor (such as the waste ammonical liquor from gas works) is stored
in a stock tank A, from whence it is discharged through the cock a into a charcoal
filter B, divided into two compartments, with a communication at their bottom.
The liquid descends through the charcoal in one compartment, and rises through
that in the next, and flows by the pipe b into a tank C, where I add to the filtered
liquor weak sulphuric acid, about 1,550 specific gravity, until the said liquor is ren-
dered neutral. I then add a little more ammoniacal liquor, just so much as will
make the solution alkaline and no more. The stirrer c is provided to aid in mixing
the acid and alkali.
The tank C is by preference covered in at the top, and the sulphureted hydrogen
given off from the liquor therein led to a furnace (not shown in the Drawings)
where it is burned, and the noxious smell thereof got rid of.
The liquor, after it has become clear by the subsidence of solid impurities, is
pumped through the pipe e into a tank E, from whence it is run in a gradual stream
through the pipe e¹ into the evaporators D, D, having in the tank E been slightly
heated by the steam from the evaporators passing through a coil of pipes d immersed
in the liquid in the said tank, the said steam afterwards escaping into the flues of
the said evaporators.
Although the evaporators D, D, may be of any convenient shape, yet I prefer
ordinary double-flued steam boilers, which are fired continually. The liquor is
allowed to overflow from the one evaporator D into the other through the pipe d¹,
and from this latter evaporator it overflows in a concentrated condition through the
pipe finto the pan F, overflowing from that again into the pan F¹: The pans F, F¹,
may be of any convenient shape. They are preferably of cast iron, and are built
with their fire-places f¹, f¹, communicating with the upper flues g, g; these upper

page_text: flues separating at the fire-bridge, from which point they extend round each side,
and thence by the downtakes h to the flues i, under the bottoms of the said pans,
and from thence to a chimney. By this mode of setting and arrangement of the flues,
the hot flame (playing upon the brick walls j, in front of and guarding the pans),
passes round them, and thence under the bottoms of the pans after the heat has
become less intense, so that the risk of burning the said bottoms is very much
lessened, whilst the heat is utilized to the best advantage.
In the pans F, F¹, the liquor is gradually increased in density, and it overflows
from the pan F¹ by the pipe k (and through a charcoal or other filter if necessary,
but which is not shown in the Drawings) into a vessel G, which may either be a
vessel similar to and heated as are the pans F, F¹, or it may be a jacketed pan
heated by steam of about fourteen or fifteen lbs. pressure on the square inch, intro-
duced into the jacket and supplied either from a steam boiler or generated in the
jacket itself. This vessel G is kept heated until crystals of sulphate of ammonia
settle out from the boiling liquor. These crystals are dipped out with a ladle as
they form. Liquor constantly flowing from the pan F' supplies the place of crystals
taken out, and the process thus goes on continuously.
When a solution of sulphate of ammonia is in process of being concentrated it
has a tendency to become acidified from the liberation of ammonia and consequent
formation of free sulphuric acid, which immediately attacks the iron vessels; but
this difficulty I overcome by adding at short intervals to the hot solutions a sub-
stance for which sulphuric acid has a greater affinity than it has for iron, the said
substance being so added in any or all of the vessels in which evaporation or con-
centration is being effected, the quantity added being so much only as is sufficient
to neutralize the newly formed acid and prevent it from taking up iron.
quantity need not exceed 100 part of the sulphate made. Any alkali will answer
for this purpose. I have used crystallized carbonate of soda with good results.
All the vessels may have a lead lining, in which case the evaporators should by
preference all be of the same shape and setting as the pans F, FL
"
The
The sulphate of ammonia produced in the operation herein-before described will
be of the quality known as good gray sulphate," and with care it may be "white,"
but if it is required to produce a quality equal to the best "London white sulphate "
it will in most cases be necessary to reboil it with water and crystallize it. This
may best be done by having another jacketed pan similar to the vessel G, into which
the product from the said vessel G, after being drained, is thrown and dissolved
with water, and from which it is dipped out in a manner similar to that herein-
before described with reference to the vessel G. When the boiling liquor in this
further vessel becomes supercharged with impurities it is baled or pumped back
into the vessel G, and the additional vessel is again charged with "gray sulphate "
and water as before.
The cyanogen compounds originally existing in the liquor are according to my
Invention separated from the sulphate of ammonia in the vessel G. On account of
their greater solubility they do not crystallize out with the sulphate until the
boiling liquor is largely charged therewith, and when, after continued working in
the manner described, that time arrives, I cease dipping out sulphate of ammonia,
stop the overflow from the pan F', and evaporate the contents of the said vessel G
to dryness. I thus obtain a mixture of sulphate, cyanide, and sulpho-cyanide of
ammonium, which can be sold as such, or still further treated for complete
separation. The vessel G is, after the obtainment of the cyanogen compounds,
again filled from the pan F', and the process is again conducted as herein-before
described.
•
The steam from the evaporators is drawn (either by a chimney draught or a
steam jet blower) through a condenser (which may be a coil) or through the pipes
d in the tank E, and the steam from the pans F, F, is drawn through the pipe f
in communication with the said pipes d. In these pipes d most of the said steam
is condensed, and the residual fumes pass through the said pipe d into the flues of
the evaporators, as aforesaid, and as shown at Figure 2, or they are preferably led

page_text: by the said pipe under and through the fire-bars of the said evaporators, whereby
the said fumes are rendered innocuous. When this process is conducted in con-
nection with gas works, the waste heat of the retort furnaces will efficiently heat
the evaporators.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the system, mode, or manner in or under which the same is or may be
used or practically carried into effect, I would observe in conclusion, that what I
consider to be novel and original and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
First. The improved process for obtaining sulphate of ammonia from ammo-
niacal liquors, essentially as herein-before described, that is to say, the maintaining
of the liquor in an alkaline or neutral condition, whereby vessels which would be
acted upon by acid liquor are capable of being used, and the process rendered con-
tinuous, also the improved arrangement or combination constituting the apparatus
for the said purposes herein-before described, and illustrated in the accompanying
Drawings.
Second. The obtainment of the cyanogen compounds of ammonium by allowing
the same to collect in the last vessel of the series, and when present therein to a
sufficient extent crystallizing thein out, as herein-before described.
In witness whereof, I, the said Peter Stuart Brown, have hereunto set iny
hand and seal, this Twenty-second day of August, in the year of our Lord
One thousand eight hundred and seventy-eight.
P. STUART BROWN. (L.S.)