IMPROVEMENTS IN THE MANUFACTURE OF SULPHATE OF SODA AND SULPHATE OR POTASH
Year: 1874

page_text: LETTERS PATENT to William Hunt, of Castleford, near Normanton,
in the County of York, Manufacturing Chemist, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF SULPHATE OF SODA AND SULPHATE
OR POTASH "
in the County of York, Manufacturing Chemist, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF SULPHATE OF SODA AND SULPHATE
OF DOMACH"
Sealed the 4th August 1874, and dated the 10th June 1874.
PROVISIONAL SPECIFICATION left by the said William Hunt at the
Office of the Commissioners of Patents, with his Petition, on the
10th June 1874.
I, WILLIAM HUNT, of Castleford, near Normanton, in the County of
York, Manufacturing Chemist, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SULPHATE OF SODA AND
SULPHATE OF POTASH," to be as follows:-
".
My Invention has reference to that method of manufacturing sulphate
of soda and sulphate of potash, in which the chloride of sodium or
potassium is converted into sulphate of soda or potash by being acted
upon in large chambers by a current of sulphurous acid gas, steam, and
atmospheric air.

page_text: I will describe my Invention as applied to the manufacture of sulphate
of soda.
In the ordinary method of manufacturing sulphate of soda by decom-
posing chloride of sodium or common salt by means of a current of
sulphurous acid gas, steam, and atmospheric air, the common salt is
prepared in the following manner :-The salt is made damp and is spread
in a layer of about nine inches thick upon a floor or surface having flues
under it. The floor or surface is previously covered with a thin layer of
dry salt. By gently tapping the layer of damp salt it is consolidated,
and by heating the floor or surface on which the salt is spread by means
of the flues underneath it the layer of damped salt is dried into a solid
or coherent mass. This layer of salt is by means of crushing machinery
broken up into pieces of about the size of a hen's egg, and the chambers
in which the decomposition is to be effected are charged with these
lumps. The action of the gaseous mixture on these lumps is slow. The
outer portions are soon decomposed, but the decomposition of the central
portions is not effected in a shorter time than between two and three
wecks.
The object of my Invention is to expedite the decomposition of the
chloride by the action of the gaseous mixture of sulphurous acid, steam,
and atmospheric air, and this I effect by making in the lumps a series of
perforations at short distances apart, by which perforations the direct
entrance of the gascous mixture into the interior of the lump is secured,
greater surface for the gaseous mixture to act upon is produced, and the
draught of the gaseous mixture through the chambers is less impeded
than when the lumps operated upon are solid.
The perforations in the lumps of salt may be made in various ways.
The salt may be damped and consolidated by heat in the usual way, but
after the tapping and before the application of heat perforations may be
made in the layer of damp salt by means of an iron or other rod about
three-eighths of an inch thick, the perforations being by preference
about an inch apart.
To facilitate the making of the perforations a board having a series of
perforations in it may be placed upon the layer of salt and a rod pushed
through the holes in the board into the salt; or a fork having two prongs
or a tool consisting of a row of rods may be used so as to make two or
a row of holes at the same time. After the layer of perforated salt has,

page_text: been heated and dried it is broken up in the usual manner.
Or instead
of perforating a layer of damp salt, as described, the damp salt may be
moulded in boxes or moulds into blocks of convenient size. These
moulding boxes are provided with a series of slightly tapering pegs,
which leave a series of corresponding holes in the blocks of salt moulded
therein. These moulded perforated blocks are dried in a stove or on a
heated floor, and when dry are fit for use in the decomposing chambers.
I do not however confine myself to any particular methods of making
the perforations.
By my Invention the decomposition of the salt is effected in less than
onc-half the time required in the ordinary process the apparatus em-
ployed being thus virtually doubled in working capability.
Further, finely ground rock salt, which from its close texture cannot
be conveniently employed in the ordinary process may be advantageously
used either alone or mixed with ordinary salt when the blocks or lumps
are perforated according to my Invention.
The application of my Invention to the manufacture of sulphate of
potash differs in no essential respect from its application to the manu-
facture of sulphate of soda.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said William Hunt in the Great Seal Patent Office
on the 8th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HUNT, of Castleford, near Normanton, in the County of York, Manu-
facturing Chemist, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of June, in the year
of our Lord One thousand eight hundred and seventy-four, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said William Hunt, Her special
license, that I, the said William Hunt, my executors, administrators,
and assigns, or such others as I, the said William Hunt, my exc-
cutors, administrators, and assigns, should at any time agree with, and
no others, from time to time and at all times thereafter during the term

page_text: therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF SULPHATE OF SODA AND SULPHATE OF POTASH," upon the
condition (amongst others) that I, the said William Hunt, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Scal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said William Hunt, do hereby declare
the nature of the said Invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say:-
My Invention has reference to that method of manufacturing sulphate
of soda and sulphate of potash in which the chloride of sodium or
potassium is converted into sulphate of soda or potash by being acted
upon in large chambers by a current of sulphurous acid gas, steam, and
atmospheric air.
I will describe my Invention as applied to the manufacture of sulphate
of soda.
In the ordinary method of manufacturing sulphate of soda by decom-
posing chloride of sodium or common salt by means of a current of
sulphurous acid gas, steam, and atmospheric air, the common salt is
prepared in the following manner :-The salt is made damp and is spread
in a layer of about nine inches thick upon a floor or surface having flues
underneath it. The floor or surface is previously covered with a thin
layer of dry salt. By tapping the layer of damp salt it is consolidated,
and by heating the floor or surface on which the salt is spread by means
of the flues underneath it the layer of damped salt is dried into a solid
or coherent mass. This layer of salt is by means of crushing machinery
broken up into pieces of about the size of a hen's egg, and the chambers
in which the decomposition is to be effected are charged with these
lumps. The action of the gascous mixture on the lumps is slow. The
outer portions are soon decomposed, but the decomposition of the central
portions is not effected in a shorter time than between two and three
weeks.
"

page_text: The object of my Invention is to expedite the decomposition of the
chloride by the action of the gaseous mixture of sulphurous acid, steam,
and atmospheric air, and this I effect by making in the lumps a series.
of perforations at short distances apart, by which perforations the direct
entrance of the gaseous mixture into the interior of the lump is secured,
greater surface for the gascous mixture to act upon is produced, and the
draught of the gascous mixture through the chambers is less impeded
than when the lumps operated upon arc solid.
The perforations in the lumps of salt may be made in various ways.
The salt is slightly damped either with water or with brine made by
dissolving rock salt in water and consolidated by heat in the usual way,
but after the tapping and before the application of heat perforations arc
made in the layer of damp salt by means of an iron or other rod about
three-eighths of an inch thick, the perforations being by preference
about an inch apart.
To facilitate the making of the perforations a board having a series of
perforations in it may be placed upon the layer of salt and a rod pushed
through the holes in the board into the salt; or a fork having two prongs
or a tool consisting of a row of prongs may be used so as to make two
or a row of holes at the same time. After the layer of perforated salt
has been heated and dried it is broken up into lumps of a convenient
size by chopping the layer or large lumps with a chisel-ended pike. The
layer of dry salt on which the damp salt is spread attaches itself in part
to the damp salt, and closes or partially closes some of the holes in the
perforated mass. By scraping the under surface of the mass or lumps
the layer of dry salt is removed and the holes are opened. Or instead
of perforating a layer of damp salt, as described, the damp.salt may be
moulded in boxes or moulds into blocks of convenient size. These
moulding boxes are provided with a series of slightly tapering pegs,
which leave a series of corresponding holes in the blocks of salt moulded
therein. These moulded perforated blocks are dried in a stove or on a
heated floor, and when dry are fit for use in the decomposing chambers.
I do not however confine myself to any particular methods of making
the perforations.
Instead of perforating a layer of damp salt or moulding perforated
blocks of salt by hand in the ways described, perforated blocks of salt
of a convenient size may be made by means of machinery.

page_text: Figure 1 represents in elevation a machine for making perforated
blocks of salt; and Figures 2, 3, and 4 represent vertical sections of the
same.
Figure 5 represents in plan and section one of the perforated blocks
made in the machine.
Figures 1 and 2 represent the machine ready to receive a charge of
salt in the moulding box.
Figure 3 represents the said machine after the salt has been com-
pressed in the moulding box and perforated; and Figure 4 represents
the machine after the perforated block has been finished and lifted out
of the moulding box ready to be removed.
The same letters indicate the same parts in Figures 1, 2, 3, and 4.
a is the moulding box provided with taper pegs e, e, by which the
perforations in the moulded block are made; b is a hopper down which
the salt in powder or fine crystals is fed to the machine; c is a carrier
or feeder for feeding the required charge of salt into the moulding box a.
When the carrier or feeder c is in the position represented in Figure 4
it is filled from the hopper b. By advancing the feeder c into the position
represented in Figure 3 the salt contained in it is delivered into the
moulding box a, and is received upon the false bottom d of the moulding
box. The pegs e, e, of the moulding box are carried by the fixed
bottomf, and pass through holes in the false bottom d. By the descent
of the plunger g the salt is compressed in the moulding box a sufficiently
to make it cohere. Before the descent of the plunger g the feeder c
retires from the position Figure 3 to the position Figure 4. On the
rising of the plunger the false bottom d also rises, carrying upon it
the perforated block of salt h, the parts of the machine now assuming
the positions represented in Figure 4. The false bottom d, with the
perforated block / upon it, is removed by the workman and another
false bottom put in its place. The last described false bottom descends
to the position Figure 2, and the charge of salt is brought over and
delivered into the moulding box, when another perforated block is
moulded in the manner before described. The motions of the plunger g
and false bottom & are effected as follows:-i is a rocking shaft having
the required motion given to it by hand or by any convenient motive
power; k, k, are crank arms on the ends of the rocking shaft i. The

page_text: I
connecting rods m, m, jointed at their lower ends to the cranks k, k, and
at their upper ends to the cross head n, give a rising and falling motion
to the said head. The plunger g is carried by the said head. The false
bottom d rests upon a frame p, sliding in the moulding box a, and the
said frame p is connected by the connecting rods q, q, to the cross head n.
The descending motion of the frame p is limited by the cross piece p³
resting on the bottom f, as seen in Figure 3. The plunger however
descends after the frame p and false bottom d have been brought to rest
in order to effect the requisite compression of the salt between the said
plunger and false bottom. This descending motion of the plunger g
after the frame p has come to rest is effected by the cross head n sliding
a certain distance upon the connecting rods q, 2, as will be understood
by reference to Figure 3, where the cross head will be seen to have
descended on the rods q, q, to carry down the plunger. The required
reciprocating motion of the feeder or carrier c may either be effected by
hand or by power. The cross head n works upon guide rods 7, 1º. The
moulded block, Figure 5, may have ribs or grooves on or in its four
sides parallel to the perforations, so that when the blocks are packed
together in the decomposing chamber there may be spaces between them
for the circulation of the gaseous mixture. The moulding box in this
case has ribs or grooves on or in its vertical sides.
The perforated blocks upon the false bottoms are carried from the
moulding machine and placed upon trays or shelves, and the latter in
frames or carriers of the kind represented in front and end clevation in
Figures 6 and 7. These frames or carriers are mounted upon wheels,
and travel upon rails or tramways, as represented. These rails or tram-
ways are fixed in a drying stove, having hot air flues in its floor, by
means of which the stove is heated and the blocks of perforated salt
dried. There are several pairs of rails or tramways in the stove, and the
length of the stove is such that the blocks as they are fed in the wheeled
frames or carriers at one end get sufficiently dried before they arrive at
the other end. The floor of the stove should be slightly inclined from
the entrance downwards so that the carriers or wheeled frames may be
moved forward by the application of a slight force.
I do not limit myself to the moulding machine or to the drying
apparatus represented.

page_text: one-half the time required in the ordinary process, the apparatus em-
ployed being thus virtually doubled in working capability.
Further, finely ground rock salt, which from its close texture cannot
be conveniently employed in the ordinary process of decomposition, may
be advantageously used either alone or mixed with ordinary salt in the
method of manufacture to which my Invention refers when the blocks
or lumps are perforated according to my Invention.
The application of my Invention to the manufacture of sulphate of
potash differs in no essential respect from its application to the manu-
facture of sulphate of soda.
Having now described the nature of my Invention and the manner in
which the same is to be performed, I wish it to be understood that I do
not limit myself to the precise details herein-before described and illus-
trated, as the same may be varied without departing from the nature of
my Invention, but I claim as my Invention the improvements in the
manufacture of sulphate of soda and sulphate of potash, herein-before
described and illustrated in the accompanying Drawings, that is to say,
perforating the lumps or blocks of chloride of sodium or potassium to
be operated upon in chambers by a mixed current of sulphurous acid
gas, atmospheric air, and steam, substantially as and for the purposes
described, whether the perforating of the said lumps or blocks be effected
by hand or by machinery.
In witness whereof, I, the said William Hunt, have hereunto
set my hand and seal, this Second day of December, in the
year of our Lord One thousand eight hundred and seventy-
foun
Witness,
THоs. H. GORLE,
Castleford,
Nr. Normanton.
WILLIAM HUNT. (L.S.)