Improvements in the Manufacture of Sulphate of Soda and in Apparatus therefor.
Year: 1887

page_text: Date of Application, 15th Oct., 1887
Complete Specification Left, 16th July, 1888
Complete Specification Accepted, 24th Aug., 1888
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Sulphate of Soda and in
Apparatus therefor.
I, DOUGLAS HERMAN of West Park, St. Helens in the county of Lancaster,
Chemical Engineer, do hereby declare the nature of this invention to be as
follows:-
The object of my invention is the production of a high quality of saltcake more
especially suited, by reason of its freedom from iron, for the manufacture of glass.
Saltcake of this description has usually been made by the following process:
Ordinary saltcake is dissolved in water, the iron oxidized by bleaching powder and
precipitated by an alkali or alkaline earth. After settling the clear liquor is boiled
down in pans nearly to dryness and the resulting mass after draining is dried in a
finishing furnace.
In my improved process the clear liquor is concentrated in pans and agitated by.
mechanical agitators or other suitable means. Under these circumstances small
anhydrous crystals of sulphate of soda are deposited which may be "fished
removed from the pans by dredgers or other suitable means.
་
"
or
After removal the
crystals are passed to hydro-extractors which quickly remove the liquor and leave the
salt cake in a finely granular condition, well adapted for the glass manufacture.
Dated this Fourteenth day of October 1887.

page_text: COMILELE DIEUIFICATION.
.
.
Improvements in the Manufacture of Sulphate of Soda and in
Apparatus therefor.
I DOUGLAS HERMAN of West Park St. Helens in the county of Lancaster Chemical
Engineer, 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 :-
The object of my invention is the production of a high quality of saltcake more
especially suited by reason of its freedom from iron for the manufacture of glass.
Saltcake of this description has usually been made by the following process.
Ordinary saltcake is dissolved in water, the iron oxidized by bleaching powder and
precipitated by an alkali or alkaline earth. After settling the clear liquor is boiled
down in pans nearly to dryness, the resulting mass after draining being dried in a
finishing furnace.
In my improved process the clear liquor is concentrated in pans and agitated by
mechanical agitators or other suitable means. Under these circumstances small
anhydrous crystals of sulphate of soda are deposited, which may be fished or removed
from the pans by dredgers or other suitable means. After removal the crystals are
passed to hydro-extractors which quickly remove the liquor, and leave the saltcake in
a finely granular condition, well adapted for the glass manufacture.
DESCRIPTION OF THE DRAWINGS.
Figs. 1 and 2 are vertical sections at right angles to each other and fig. 3 a plan
part being in section, of apparatus suitable for carrying my improved manufacture into
effect. 1 boiling down pan constructed of metal in any usual or suitable manner.
2 carrying walls. 3 air spaces and openings to prevent the metal of the pan from
becoming too highly heated and to allow of access for cleaning. 4 furnace. 5 flue
over surface of the liquor in the pan. 6 chimney. The furnace is of ordinary con-
struction as shown or may be of the so called plus pressure or producer forms or as
may be otherwise found desirable. The carrying and furnace and flue walls are of
brickwork, strengthened by metal in any suitable way. 7 endless chain carried on
pulleys 8 and provided with dredging boards 9. 8x is the driving pulley carried in
oscillating bearings. 10 shoot. 11 centrifugal hydro-extractor. The dredging
appliances may be of any suitable construction, and may deliver into a hopper instead
of onto a shoot. The centrifugal hydro-extractors may be intermittent or continuous
in action. The dredging appliances may be fitted with agitating paddles, or separate
agitating appliances, such as rotating beaters, oscillating arms, or air or steam jets
may be used. 12 are perforated pipes to allow of steam or heated water being ejected
against the upper edges of the pan to remove incrustation. The solution of saltcake
under my invention is fed to the pan in any convenient way, and heated and caused
to evaporate by the products of combustion passing over its surface. As the liquor
becomes concentrated anhydrous crystals of sulphate of soda are precipitated and are

page_text: removed by the dredger from the bottom of the pan and deposited in the hydro-
extractor by means of the shoot. The crystals are removed from the hydro-extractor
intermittently or continuously. When a shoot is used the pulley 8× is raised to the
position shown by the dotted lines when it is not desired to carry forward the crystals
to the shoot, say when the hydro-extractor is at rest to allow of removal of the dried
crystals. When a hopper is used instead of a shoot, a shutter may be used to retain
the crystals.
If discolouration of the crystals is objectionable smokeless fuel or producer, or
other suitable gas is used instead of a furnace, or the pan is heated as hereinafter
setforth.
Figs. 4 and 5 are vertical sections at right angles to each other of a modified
construction of apparatus under my invention. Here an endless worm 13 is used to
cause the precipitated crystals to travel from one end of the pan to the other, and a
worm or bucket elevator 14 is used to remove the crystals from the pan, and deposit
them in the hydro-extractor 11.
Fig. 6 is a transverse section of a pan in which the products of combustion or heated
gases do not come into contact with the liquor to be concentrated, but in which the
heat is transmitted from one to the other through the walls of the pan. In this
manner discolouration of the crystals is avoided. The same letters refer to parts
equivalent to those previously described.
The fineness of the crystals is regulated by the rapidity of evaporation and the
amount of agitation imparted to the liquor under treatment.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
First. Obtaining high quality sulphate of soda by concentrating and precipitating a
solution of saltcake from which the iron has been removed, the concentration being
effected and the precipitated crystals removed and dried substantially as setforth.
Second. Apparatus combined substantially as setforth for obtaining high quality
sulphate of soda under my invention.