Ash, and the Recovery of Ammonia therefrom.
Year: 1886

page_text: Date of Application, 20th Apr., 1886.
Complete Left, 19th Jan., 1887.
Complete Accepted, 22nd Feb.; 1887.
Ash, and the Recovery of Ammonia therefrom.
We, THOMAS TRAIN MATHIESON, of 9 Croxteth Road, Liverpool, in the County of
Lancaster, Chemical Manufacturer, and JOSEF HAWLICZEK, of 40 Bentley Road,
Liverpool, aforesaid, Chemist, do hereby declare the nature of our said invention to be
as follows:-
This invention relates to a new method for purifying crude carbonate of soda,
termed black ash by decomposition of the cyanide and sulphide compounds, and the
recovery of ammonia therefrom.
The crude soda or black ash made by the Le Blanc" process contains certain
impurities notably cyanide and sulphide compounds which by lixiviation are in the
usual way carried forward in the liquor causing much inconvenience and expense in
further treatment for the manufacture of caustic or carbonate of soda.
It is the usual practice to destroy the cyanides and sulphides by treatment in the
furnace, or in the black ash liquor, these methods are, however, costly and therefore in
many cases cannot be adopted.
Our invention consists in treating black ash in the manner hereafter described at a
certain temperature with steam which may be superheated, the cyanide compounds are
entirely decomposed and ammonia in a gaseous form is evolved which may be
recovered in any suitable way.
After the above decomposition (which must necessarily be carried on at a lower
temperature) has taken place, we have found that if the black ash is further treated, in
a similar way, but at a higher temperature, the sulphides in combination with the soda
are decomposed with evolution of sulphuretted hydrogen and consequent equivalent
gain of caustic soda.
In carrying out our invention we break the black ash balls into convenient sized

page_text: -lumps-as-soon-after-being-drawn-from-the-furnace-as possible thus gaining a great
amount of the heat necessary for decomposition, and we place, the lumps of black ash
in a suitable closed vessel for treatment with steam, which may be superheated; or we
break the black ash while cold and then reheat it and apply steam as above.
The decomposition of the cyanides takes place very rapidly and ammonia is formed
which passes over with the steam and may be condensed, or absorbed as desired.
By further similar treatment in the same vessel, but at a higher temperature the
sulphides in combination with the soda are decomposed and sulphuretted hydrogen is
given off leaving in the black ash the equivalent gain of soda.
THOMAS TRAIN MATHIESON.
JOSEF HAWLICZEK.
COMPLETE SPECIFICATION.
A Method for Purifying Crude Carbonate of Soda, Termed Black
Ash, and the Recovery of Ammonia therefrom.
We, THOMAS TRAIN MATHIESON, of 9 Croxteth Road, Liverpool, in the County of
Lancaster, Chemical Manufacturer, and JOSEF HAWLICZEK, of 40 Bentley Road,
Liverpool, aforesaid Chemist, do hereby declare the nature of our said invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This Invention relates to the purification of crude carbonate of soda termeil
black ash."
The crude carbonate of soda "black ash" manufactured by the Leblanc process
contains certain impurities, which notably consist of cyanide and sulphide compounds
and which by lixiviation are in the usual way carried forward into the carbonate
liquor, causing much inconvenience and expense in the further treatment for the
manufacture of caustic, or carbonate of soda.
It was up to the present time the usual practice to destroy the cyanide and sulphate
compounds either in the crude carbonate liquor (black ash liquor), or in the furnace
by calcination, or in the fused caustic soda (in the latter case by addition of nitrate of
soda). These methods are however costly and inconvenient and therefore in many
cases cannot be adopted,
:

page_text: Our Invention consists in treating direct the crude carbonate of soda in the manner
hereafter described with saturated steam, or superheated steam at a certain
temperature, which may be between 600°-900° F the cyande compounds are thus
entirely decomposed and ammonia in a gaseous state is formed therefrom, which along
with the excess of steam may be either condensed or recovered in any known suitable
way.
After the above decomposition, which necessarily must be carried on at such a
temperature (such as that above specified) as will prevent the destruction of the
ammonia formed, has taken place, we subject the crude carbonate to a similar
treatment, but at a higher temperature, the sulphide compounds are thereby
decomposed with the resulting evolution of sulphuretted hydrogen and a consequent
gain of caustic soda.
It is a well known fact that the formation of cyanide compounds in the crude
carbonate of soda made by the Leblanc process is due to the nitrogen compounds in
the mixing fuel. We utilize this fact in connection with the recovery of aminonia
from the crude carbonate of soda by the method above described (when it is desirable
to obtain a large yield of ammonia) by employing a mixing fuel containing a high
per centage of nitrogen. This feature in the working of the Leblanc process is prior
to the present time contrary to the usual practice.
In carrying out our Invention we preferably break the black ash balls into
convenient sized lumps, say of about three inches diameter, as soon after being drawn
from the black ash furnace as possible thus we utilize the sensible heat of the black
ash and thereby facilitate the production of the heat necessary for the decomposition
of the impurities.
:
We first place the broken lumps of black ash while hot in a suitable closed vessel
hereafter called the "Decomposer" and allow them to cool down to the temperature
required for decomposition of the cyanide compounds (which is between 600°-900° F);
we then apply the steam which may be of about the same temperature as the charge
in the "Decomposer." The cyanides thus operated upon are entirely decomposed and
ammonia in a gaseous state is formed which along with some of the steam is carried
away and may easily be condensed, or utilized as required.
If in case it is required to break the black ash in a cold state and place it in the
Decomposer" in that state, it is necessary that the material should be reheated to
the required temperature of decomposition; this operation however may be carried out
either by external heat, or by superheated steam at the required temperature.
After the decomposition of the cyanide compound has taken place we continue the
treatment of the black ash in the same vessel and in a similar way as above, but
with steam at a raised temperature say from 1000° to 1200° F ; the sulphides in
combination with the soda will be thus acted upon and decomposed, sulphuretted
hydrogen is given off leaving in the black ash an equivalent gain of soda. We
preferably effect the decomposition of the sulphides by the application of steam
superheated to the required degree of heat.
Figure 1 of the Drawings hereto annexed illustrates a convenient apparatus, or
plant, in elevation, for carrying out the above. described method for purifying crude
carbonate of soda and for the recovery of ammonia therefrom.
Figure 2 is a plan of Figure 1.
Figure 3 is a section through one of the "Decomposers" shown in Figure 1.
With reference to the Drawings there are three cylindrical " Decomposers" A
shown which are provided with close charging apertures a having close fitting
doors a¹ of ordinary construction through which the crude carbonate of soda is
supplied. At the lower portion of each of the "Decomposers" there is provided a
discharging door 6 having a close fitting door b¹ similar to the charging doors.
e designates a bed for supporting the material in the Decomposers and is made of
interspaced bars. d are steam pipes provided with valves d' through which the steam
enters the "Decomposers" and e are pipes for the outlet of the
gases resulting from
the decompositions which take place within the "Decomposers and for the steam
that may pass over with them. The pipes e are provided with valves e¹ and have a

page_text: common pipe which leads the gases-and-steam-to-a-condenser, of ordinary construction
shown at . B is a travelling hopper having crushingrollers g of ordinary construction
for breaking the'black' ash into suitable sized lumps., The rollers may be driven By
an' engine shown at /i in dotted lines suitably secured to the frame of the hopper B.
Below the rollers'g'iliere is a dicti (shown in dotted lines) made to correspond with
the openings a. The hopper B travels upon rails . are pipes for testing, the
temperatures of the "Decomposers."
The décomposers are charged by bringing the duct of the charged hopper B fairly
over a mouth a, (having first had its cover a removed) when the rollers are set in
motion thereby crushing the black ash and feeding into, the "decomposers." The
decomposers may in this way be'fed seriatim. When a decomposer" is charged
the door a¹ is closed and steam is turned on by the valve d¹. It then rises up
through the spaces in the bed, or floor permeating the mass of black ash and operates
upon the mass in the manner above specified, namely the cyanides are first decomposed.
and form ammonia; afterwards by supplying steam of a higher temperature, the
sulphides are decomposed forming sulphuretted hydrogen. The ammonia first and
then the sulphuretted hydrogen with some of the steain are conveyed through the
pipes e and to the condenser at D where they are condensed; the ammonia is thus
obtained and can then be recovered in any suitable known way.
::
In working according to the herein described method the decomposers are kept
full of steam and a small quantity may be passed with the other gases through the
escape pipes e.
Having now particularly described and ascertained the nature of our said Invention
and in what manner the same is to be performed we declare that what we claim is
First. The method of purifying crude carbonate of soda, or "black ash" herein set
forth which consists in treating the crude carbonate of soila with steam as described
whereby the impurities in the form of cyanides and sulphides are decomposed and
driven off.
Second. The herein described method of obtaining, or recovering ammonia from
crude carbonate of soda, or black ash made with, or without a mixing fuel high in
nitrogen, which consists in treating the crude carbonate of soda with steam in a closed
chamber whereby the cyanides are decomposed and ammonia given off which is then
led away and condensed.
Third. In the method herein described for purifying crude carbonate of soda, or
"black ash" with steam, introducing the crude carbonate of soda into the vessels in
which it is treated in a heated state directly from the "black ash" furnace and broken,
or crushed into pieces substantially as set forth.