IMPROVEMENTS IN THE MANUFACTURE OF SULPHATES OF SODA AND POTASH, AND IN THE APPARATUS EMPLOYED THEREIN.” PROVISIONAL SPECIFICATION
Year: 1877

page_text: LETTERS PATENT to William Black, of Hedworth, near South Shields, and
David Hill, of East Jarrow, South Shields, both in the County of Durham, for
the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF SULPHATES OF
SODA AND POTASH, AND IN THE APPARATUS EMPLOYED THEREIN.”
PROVISIONAL SPECIFICATION left by the said William Black and David
Hill at the Office of the Commissioners of Patents on the 14th June 1877.
WILLIAM BLACK, of Hedworth, near South Shields, and David HILL, of East
Jarrow, South Shields, both in the County of Durham. "IMPROVEMENTS IN THE
MANUFACTURE OF SULPHATES OF SODA AND POTASH, AND IN THE APPARATUS
EMPLOYED THEREIN."
According to the ordinary method of manufacturing sulphates of soda and potash
from common salt and muriate of potash and sulphuric acid, it has been customary
to charge the materials into a hemispherical metal pan set in brickwork with a fire
underneath, and an arch over the top with suitable openings to allow the hydro-
chloric acid to escape, and to allow the batch of material when it has attained a
suitable consistance to be cast or thrown into an adjoining furnace, where it is dried
or roasted until the remainder of the hydrochloric acid is entirely driven off, when
it is considered fit to draw. The process as thus conducted is a very costly one for
labour, repairs, and fuel, and besides waste of material the finished product is not of
uniform quality. In consesquence also of the frequent opening of the doors by
the workmen at the various stages of the process, the hydrochloric acid gas is
more or less-diluted with air which is a great hindrance to perfect condensation.
By the arrangements herein-after described we dispense to a large extent with
the labour hitherto required in the process, diminish the cost of repairs, "save
materials and fuel, and further obtain the hydrochloric acid gas in a more concen-
trated form than hitherto, and therefore in a much more suitable condition to obtain
perfect condensation.
We find that it is desirable to diminish as far as possible the amount of work
required in the decomposing process proper, and that to this end the materials should
Imine B1

page_text: be in the most suitable condition for promoting a rapid decomposition. We there-
fore regard it as of great importance that the common salt or muriate of potash
should be as dry as possible, and where this is not so we dry the common salt or
muriate of potash by waste heat or otherwise, and use the salts in the warm state
in the decomposing apparatus. It is also of great importance that the sulphuric
acid used should be as strong and hot as possible.
By operating with dry and warm salt and with strong and hot acid, the apparatus
in which the principal operation is conducted is saved from the risks attendant upon
extensive range of temperature, and rendered more durable at the same time that it
is enabled to do more work.
In carrying out our Invention we take the materials in the condition described
and in charges of, say, from about forty to one hundred hundredweights of the salts
to be treated, together with the calculated quantity of sulphuric acid necessary for
their decomposition, and place them in a metal cylinder set horizontally, provided
with suitable inlets for charging the salt and acid in the top, and with a convenient
outlet in the top for the hydrochloric acid gas, and openings near the bottom at the
ends for the discharge of the batch when it has obtained a proper consistance. The
latter opening may be closed with a door, tap, or properly fitted slide. The cylinder
has also openings in the ends near the top provided, through which rakes may be
inserted in order to stir the mixture, but we prefer to have a horizontal shaft with
blades or stirrers fixed and driven by suitable gearing working entirely within the
cylinder. The bearings of the shaft are also within the cylinder, and we in this
manner avoid the trouble of maintaining joints in the ends of the cylinder, and also
avoid the risk of leakage.
We prefer to run in all the acid constituting a charge at once, and only from 70
to 80 per cent. of the salt constituting a charge, leaving the remainder 30 to 20 per
cent. to be added at the last, just before the batch is ready to be discharged from the
cylinder. By operating in this manner the mixture of acid and salt is retained in a
more liquid form, which is favourable to rapid evolution of the hydrochloric acid gas,
and besides prevents the charge sticking to the cylinder; and contact being more
regular there is less difference between the temperature of the cylinder and the
enclosed mass.
The cylinder may be heated by the waste heat from a furnace in which the
contents of the cylinder is finished; and under the most favorable conditions of dry
and warm salt, and hot and strong acid, this will be sufficient; but where these
conditions are not attained it will be necessary to sacrifice quantity in the work or to
heat the cylinder by an independent fire.
The cylinder is placed at, say, about three feet above the level of the finishing
furnace, and so that the end of the cylinder, and the edge of the furnace are nearly
in the same perpendicular. When the contents of the cylinder have attained a
suitable consistance, the slide is drawn from the opening in the end, and the charge
is allowed to flow into a mechanical furnace, which may either be a revolving bed
with stirrers, either fixed or moveable, dependent from the arch, or it may consist of
a fixed circular bed provided with a central shaft with arms having scrapers attached
revolving in the furnace.
In either case the mass is heated until the hydrochloric acid is expelled as far as
practicable when the batch can be drawn from the furnace.
By operating in the manner described and apportioning the work, we obtain a
great saving of labor and fuel, and effect a saving in repairs, besides getting more
constant and uniform results with economy of materials, and we obtain the hydro-
chloric acid gas in the best condition for obtaining perfect condensation thereof.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said William Black and David Hill in the Great Seal Patent Office on the
11th December 1877.
WILLIAM BLACK, of Hedworth, near South Shields, and DAVID HILL, of East
5 Jarrow, South Shields, both in the County of Durham. "IMPROVEMENTS IN THE
MANUFACTURE OF SULPHATES OF SODA AND POTASH, AND IN THE APPARATUS
EMPLOYED THEREIN.”
:
According to the ordinary method of manufacturing sulphate of soda from common
salt and sulphuric acid, and of manufacturing sulphates of potash from muriate of
O potash and sulphuric acid, it has been customary to charge the materials into a
hemispherical metal pan, set in brickwork with a fire underneath and an arch over
the top, with suitable openings for the escape of the hydrochloric acid, and to admit
of the batch of material on its attaining a suitable consistence being cast or thrown
into an adjoining furnace; where it is dried or roasted until the remainder of the
5 hydrochloric acid is entirely driven off, when it is considered fit to draw. The
process as thus conducted is a very costly one in respect of labour, repairs, and fuel,
in addition to which a considerable waste of material takes place, and the finished
product is not of uniform quality. As moreover it is requisite to open the doors at
the various stages of the process a certain quantity of air gains access to the interior,
O whereby the hydrochloric acid gas becomes more or less diluted, and its perfect
condensation is consequently impeded.
By the arrangements herein-after described we dispense to a large extent with the
labor hitherto required in the process, diminish the cost of repairs, effect a saving in
materials and fuel, and further obtain the hydrochloric acid gas in a more concen-
5 trated form than heretofore, and therefore in a much more suitable condition for
obtaining perfect condensation.
We find that it is desirable to diminish as far as possible the amount of work
required in the decomposing process proper, and that to this end the materials should
be in the most suitable condition for promoting a rapid decomposition. We there-
0 fore regard it as of great importance that the common salt or muriate of potash
should be as dry as possible, and where this is not so we dry the common salt or
muriate of potash by waste heat or otherwise, and use the salts in a warın condition
in the decomposing apparatus. It is also of great importance that the sulphuric
acid used should be as strong and hot as possible.
By operating with dry and warm salts and with strong and hot acid, the risks
attendant upon extensive range of temperature to which the apparatus in which the
principal operation is conducted is exposed are obviated, and the apparatus is
rendered more durable, at the same time that it is enabled to do more work.
In carrying out our said Invention we employ apparatus constructed and arranged
substantially in the manner shewn in the accompanying Sheet of Drawings, which
we shall now proceed to describe.
Figure 1 of our Drawings represents a side sectional elevation of the apparatus ;
Figure 2 is an end sectional elevation; and Fig. 3 a sectional plan of the same, both
corresponding to Figure 1.
The same letters of reference indicate corresponding parts in all the Figures.
This
A is a cylinder or receptacle (which may be of any convenient shape) set hori-
zontally in brickwork or masonry B, so as to be heated by gaseous products of com-
bustion traversing flues C beneath it, or in any other convenient manner.
cylinder, which may be constructed either wholly of metal or (as shewn) with the
upper portion of brickwork, is provided on the top with an aperture capable of
being hermetically closed by a door a for the charging of the common salt or muriate
of potash with a pipe 6 for the introduction of the sulphuric acid, and with a pipe ċ
for the escape of the hydrochloric acid, and is formed at the bottom at its ends with
apertures (closed by slides d, d', or otherwise) for the discharge of the batch when

page_text: it has attained a proper consistence. Openings may also be provided in the ends
near the top for the introduction of rakes, which may be driven by machinery for
the purpose of stirring the mixture, or the stirrers may consist of two or more,
vertical shafts suspended in the cylinder with supports at the exterior, and fitted
with blades having a sweep equal to the bottom section of the cylinder, the same
being driven by machinery, but we prefer to employ stirrers, as shown at D in the
Drawings, such stirrers consisting by preference of blades secured to a revolving
horizontal shaft E situate within the cylinder, and having its bearings at c, also
within the latter, so as to obviate the necessity for the use of stuffing boxes in the
ends of the cylinder, and also the liability of leakage.
The requisite rotary motion may be imparted to the horizontal shaft E through
the intervention of gearing f of a vertical shaft F extending through the top of
the cylinder, and of bevel gearing 7 from another horizontal shaft G which is
supported in bearings at h, h, and carries a pulley H driven from any suitable prime
mover.
We take the materials in the condition described, and in charges of, say, from about
forty to one hundred hundredweights of the common salt or muriate of potash to be
treated, and the calculated quantity of sulphuric acid necessary for its decom-
position, and introduce them through their respective openings a, b, into the
cylinder A.
We prefer to run in all the acid constituting a charge at once, and only from seventy
to eighty per cent. of the salt constituting a charge, leaving the remaining thirty to
twenty per cent. to be added at the last, just before the batch is ready to be discharged
from the cylinder. By operating in this manner the mixture of acid and salt is retained
in a more liquid form, which is favorable to rapid evolution of the hydrochloric acid gas,
and moreover prevents the charge from adhering to the cylinder; and contact being
more regular there is less difference between the temperature of the cylinder and the
enclosed mass.
The cylinder A may be heated by the waste heat from a furnace I (herein-after
described) in which the contents of the cylinder A are finished; and under the most
favorable conditions of dry and warm salt and hot and strong acid, this will be
sufficient; but where these conditions are not attained it will be necessary to
sacrifice quantity in the work, or to heat the cylinder by an independent fire.
We find in practice that the heat remaining in the waste gases escaping by the
flues C from under the cylinder A is sufficient to dry the salt.
The cylinder is placed at, say, about three feet above the level of the finishing
furnace I, and so that the end of the cylinder and the edge of the furnace are nearly
in the same perpendicular. When the contents of the cylinder have attained a
suitable consistence, the slide d is drawn from the opening in one end of the cylinder,
and the charge is allowed to flow through a shoot (also fitted with a slide ³)
into the finishing furnace.
In the example shewn in our Drawings this furnace consists of a chainber h¹,
heated by a fire at 2, and containing a fixed circular bed or trough i, in the centre
of which is arranged a vertical revolving shaft, having arms with scrapers m
attached to the shaft, which is suitably supported at its lower end by the bed, and at
its upper end by a bearing at n being driven by means of the gearing o, shaft p;
gearing g, shaft r, and pulley 8, from any suitable prime mover; or in lieu of this
arrangement a revolving bed may be used in combination with stirrers, either fixed
or moveable, dependant from above.
In either case the mass is heated until the hydrochloric acid is expelled as far as
practicable, when the batch can be drawn from the furnace. The moveable parts of
the finishing furnace may be driven by gearing connected with the gearing for
operating the blades or stirrers of the cylinder if desired.
By operating in the manner herein-before described and apportioning the work;
we effect a considerable saving in labor, fuel, and repairs, whilst producing more
constant and uniform results with economy of materials, in addition to which

page_text: 5
advantages the hydrochloric acid gas is obtained in the best condition for effecting
its perfect condensation.
We claim as our Invention, manufacturing sulphates of soda and potash, sub-
stantially in the manner and by the means herein-before described.
In witness whereof, wc, the said William Black and David Hill, have to
this our Specification set our hands and seals, the Eighth day of December,
One thousand eight hundred and seventy-seven.
WILLIAM BLACK. (L.s.)
DAVID HILL.
(L.B.)