IMPROVEMENTS IN THE MANufacture of SULPHATES
Year: 1880

page_text: LETTERS PATENT to James Hargreaves, of Widnes, in the County of
Lancaster, Chemist, and Thomas Robinson, of the same Place, Iron Founder,
for an Invention of
56
IMPROVEMENTS IN THE MANufacture of SULPHATES
PROVISIONAL SPECIFICATION left by the said James Hargreaves and
Thomas Robinson at the Office of the Commissioners of Patents on the
24th November 1880.
JAMES HARGREAVES, of Widnes, in the County of Lancaster, Chemist, and
THOMAS ROBINSON, of the same Place, Iron Founder. "IMPROVEMENTS IN THE
MANUFACTURE OF SULPHATES OF SODA AND POTASSA, AND IN. APPARATUS
EMPLOYED THEREIN."
The said Invention relates to the manufacture of sulphates of soda and potassa
by the direct action on the chlorides of soda and potassa of sulphurous acid gas,
air, and water vapour, commonly known as the Hargreaves & Robinson process.
The main objects are to cheapen the manufacture of sulphates, to facilitate
working, and to make the plant more suitable and durable.
First Part. In order to obtain a larger quantity of sulphuric acid in the
sulphurous acid gas obtained by the combustion of sulphur or pyrites, and at the
same time provide means for removing any dust carried off in suspension from
burning pyrites, the said sulphurous acid gas mixed with air and water vapour is
caused to pass through a kind of filter consisting of a chamber or vessel or chambers
or vessels filled or partly filled with metallic oxides, preferably of iron or copper.
A mass of broken and burnt cupreous iron pyrites is found to answer well. The
filter of oxide is used either in a single mass for the entire series of burners or a
separate filter is used for each.
Second Part. The heat developed by chemical reactions and the combustion of
pyrites or sulphur in the manufacture of sulphates of soda and potassa by the said
Hargreaves and Robinson process is when loss of heat by radiation is prevented in
excess of that required to maintain the contents of the converting chambers at the
requisite temperature; in fact, fuel is only. required for raising the newly charged
Price 6d1

page_text: chlorides to the temperature necessary for the commencement of the reactions;
hence it arises that during the conversion of chlorides into sulphates it is sometimes
necessary to cool the materials in order to prevent such an elevation of temperature
as shall fuse the chloride. The cooling is effected by admitting cold air into the
decomposing chambers, and it sometimes happens that by an error of judgement
the said cooling is carried so far as to cause the reactions to take place too slowly;
under these circumstances it is necessary to slightly reheat the contents of the
chambers.
Now, with decomposing chambers of large diameter it is very difficult to transmit
heat to the contents of the said chambers, as the surfaces for the transmission of
heat are small in proportion to the mass of the contents; furthermore, it is difficult
to conduct heat to the centre of the mass or the parts distant from the walls of the
chambers.
To overcome the above difficulties, and rapidly, economically, and uniformly
raise the temperature of the said materials, the gases circulating in the said
apparatus are heated at or near the point where they enter the chamber the
contents of which requires heating. To heat the said gases a portable furnace is
used, preferably constructed so that a draught of air enters at the top and sides of
the mass of fuel undergoing combustion, whilst the products of combustion pass
away at or near the bottom.
The products of combustion pass from the portable furnace at a very high
temperature and at a great velocity, so that it is necessary that they should not
impinge on any part of the apparatus or on the chloride or sulphate contained in
the said decomposing chambers. The said products of combustion are therefore
caused to mix with the circulating gases by, entering the pipe or tube through
which the circulating gases are passing to the chamber to be heated at or near the
axis of the said pipe or tube in a direction contrary to that taken by the gases
when circulating in the usual course of working. The said current of products of.
combustion imparts its heat to the gases without impinging on any part of the
apparatus or of the contents thereof. The ashes or fused slag produced in the
said portable furnace are allowed to fall into the said pipe or tube, at the bottom
of which they remain until the preceding chamber is discharged, when they are
removed, or a special receptacle may be provided for the said ashes or slag. When
combustible gases are easily procurable such gases may be used in place of the
products of combustion from the portable furnace.
Third Part. In order to render the apparatus employed in the manufacture of
sulphates more compact, and to minimise the loss of heat by radiation, the apparatus
for drying the chlorides to be converted into sulphates is placed above and between
two lines of decomposing chambers over the hydrochloric acid flue. The salt
drying apparatus is preferably heated by gascous fuel.
Fourth Part. To obtain decomposing chambers of large diameter, which shall be
easily constructed and erected, such chambers are made of segments held together
by dovetail pieces. Projections are cast on each segment enclosing spaces of such
form as to hold one end of the said dovetail pieces. The said projections on each
segment correspond and are opposite to each other when the segments are in their
places so that the dovetail pieces may be inserted and hold the segments together.
The spaces enclosed by the projections is increased in area from the exterior to the
interior, and the dovetail pieces are made of greater area at the back than at the
front. The areas of the backs of the dovetail pieces are such that the said pieces
shall only just enter the spaces between the said projections, but when in position.
shall leave sufficient space for caulking round the sides so that the joint may be
made hermetically close and the passage of air therethrough prevented. The.
intermediate parts of the sides of the segments are held together by bolts inserted
through flanges so disposed as to leave caulking spaces.
The covers of the said decomposing chambers are made of pieces held together by
dovetail connections in the manner above described for the segments. The tops of
the chambers and the cylinder formed by the segments are connected together by

page_text: .
grooves and flanges or ribs, spaces being left for caulking. When sulphate is
wanted of great purity and free from iron the sides of the decomposing chambers
and grids are covered with a layer of silicate of soda or potash, applied in solution
and allowed to dry.
Fifth Part. Experience has shown that as decomposing chambers are increased
in diameter less fuel is required to maintain the materials being treated at the
requisite temperature, and that the manufacture of sulphates is conducted with
greater economy and regularity, but that more labour is required for discharging
the finished sulphate, in consequence of the greater distance through which it must
be moved to enable it to be taken out of the decomposing chamber.
To minimise the above disadvantage passages are so made to the discharge
openings and doors through the walls enclosing the chambers that workmen can
approach close to the material which is to be discharged without entering the
chambers, and barrows or receptacles used in conveying away the sulphate may be
placed against the said cylinders and the finished sulphate raked directly into the
said barrows or receptacles without being shoveled over the door plates as has
heretofore been necessary.
Sixth Part. To further facilitate discharging the contents of decomposing
chambers, the said chambers are constructed with one or more openings in the
bottoms or floors thereof, and suitable discharge necks are provided to allow the
said sulphates to fall into an arched passage or other suitable space below the level
of the said decomposing chambers. The said passages or spaces extend transversely
or longitudinally from side to side or end to end of the lines of chambers.
The above mentioned discharge necks are attached to the bottoms or floors of the
decomposing chambers and are closed with upper and lower covers to prevent air
entering the chambers whilst the apparatus is working. To prevent loss of heat by
conduction from the inside of the chambers the space between the covers is filled
with sulphate of soda or other bad conductor of heat. The lower cover is
hermetically closed by means of a mixture of common salt and mortar and is held in
its place by screws passing through lugs on the discharge necks.
The passages or spaces under the decomposing chambers may serve as temporary
magazines for the sulphate, or rails are laid and the sulphate discharged directly
into wagons. In some cases the sulphate is discharged on endless travelling bands or
plates or on archimedian screws, and thence conveyed or elevated to any desired
place.
Seventh Part. To prevent loss of heat from the outer walls which enclose the
decomposing chambers the said walls are constructed with a cavity or cavities
along their length filled with plaster of Paris whilst in the liquid state by
admixture with water. It is preferable that the walls should be built, say, half a
metre in height at a time, and the cavity filled with the aforesaid mixture of plaster
of Paris and water, which is allowed to set hard before the walls are again built on.
Plaster of Paris when dried is an exceedingly slow conductor of heat, and when so
made there is much less loss of heat than with thicker walls when bricks or stones
and mortar are alone used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Hargreaves and Thomas Robinson in the Great Seal Patent
Office on the 24th May 1881.
JAMES HARGREAVES, of Widnes, in the County of Lancaster, Chemist, and
THOMAS ROBINSON, of the same Place, Iron Founder. "IMPROVEMENTS IN THE
MANUFACTURE OF SULPHATES OF SODA AND POTASSA, AND IN APPARATUS
EMPLOYED THEREIN."
The said Invention relates to the manufacture of sulphates of soda and potassa,
by the direct action on the chlorides of soda and potassa of sulphurous acid gas,
air, and water vapour, commonly known as the Hargreaves and Robinson process.
The main objects are to cheapen the manufacture of sulphates, to facilitate
working, and to make the plant more suitable and durable.
First Part. In order to obtain a larger quantity of sulphuric acid in the
sulphurous acid gas obtained by the combustion of sulphur or pyrites, and at the same
time provide means for removing any dust carried off in suspension from burning
pyrites, the said sulphurous acid gas mixed with air and water vapour is caused to
pass through a kind of filter, consisting of a chamber or vessel, or chambers or
vessels, filled or partly filled with metallic oxides, preferably of iron or copper.
A mass of broken and burnt cupreous iron pyrites is found to answer well. The
filter of oxide is used either in a single mass for the entire series of burners, or a
separate filter is used for each.
Figs. 1 to 11 are views of apparatus suitable for carrying out the above first
part of our Invention.
Fig. 1 is a sectional elevation, and Fig. 2 a plan view of a combined pyrites
burners and filter. 1, burners; 2, perforated roofs; 3, layer of metallic oxide
directly over the burners; 4, flue leading from one end of the burners to
converting chambers.
Figs. 3 and 4, longitudinal and transverse sections of burners and filters similar
to the above, except that the flue 4 opens to the centre of the space over the filter-
beds 3.
Fig. 5 is a sectional elevation, and Fig. 6 a plan view, partly in section, of
apparatus in which the sulphurous acid gas from all the burners passes through a
filter bed 3 over one end of the burners.
Fig. 7 shows apparatus in which the filter bed 3 is quite separate from the
pyrites burners 1.
Figs. 8, 9, and 10 are sectional elevations, and Fig. 11 a plan view of burners
for powdered pyrites combined with filters. In Fig. 8 the filter bed 3 is directly
over the burners, in Fig. 9 the said filter-bed is separate. from the burners, and in
Figs. 9 and 10 the filter-bed 3 is placed over an arched passage between the
burners.
Second Part. The heat developed by chemical reactions and the combustion of
pyrites or sulphur in the manufacture of sulphates of soda and potassa by the said
Hargreaves and Robinson process is, when loss of heat by radiation is prevented,
in excess of that required to maintain the contents of the converting chambers at
the requisite temperature; in fact, fuel is only required for raising the newly-
charged chlorides to the temperature necessary for the commencement of the
reactions. Hence it arises that during the conversion of chlorides into sulphates it
is sometimes necessary to cool the materials in order to prevent such an elevation
of temperature as shall fuse the chloride. The cooling is effected by admitting
cold air into the decomposing chambers, and it sometimes happens that by an error
of judgement the said cooling is carried so far as to cause the reactions to take

page_text: place too slowly. Under these circumstances it is necessary to slightly reheat the
contents of the chambers.
Now with decomposing chambers of large diameter it is very difficult totransmit
heat to the contents of the said chambers, as the surfaces for the transmission of
heat are small in proportion to the mass of the contents. Furthermore, it is
difficult to conduct heat to the centre of the mass, or the parts distant from the
walls of the chambers.
To overcome the above difficulties, and rapidly, economically, and uniformly
raise the temperature of the said materials, the gases circulating in the said
apparatus are heated at or near the point where they enter the chamber, the
contents of which requires heating. To heat the said gases a portable furnace is
used, preferably constructed so that a draught of air enters at the top and sides of
the mass of fuel undergoing combustion, whilst the products of combustion pass
away at or near the bottom.
The products of combustion pass from the portable furnace at a very high
temperature, and at a great velocity, so that it is necessary that they should not
impinge on any part of the apparatus, or on the chloride or sulphate contained in
the said decomposing chambers. The said products of combustion are therefore
caused to mix with the circulating gases by entering the pipe or tube through
which the circulating gases are passing to the chamber to be heated at or near the
axis of the said pipe or tube in a direction contrary to that taken by the gases
when circulating in the usual course of working. The said current of products of
combustion imparts its heat to the gases without impinging on any part of the
apparatus, or of the contents thereof. The ashes or fused slag produced in the said
portable furnace are allowed to fall into the said pipe or tube, at the bottom of
which they remain until the preceding chamber is discharged, when they are
removed; or a special receptacle may be provided for the said ashes or slag. When
combustible gases are easily procurable such gases may be used in place of the
products of combustion from the portable furnace.
Fig. 12 is a sectional elevation, and Fig. 13 a plan view of so much of sulphate-
making apparatus as is necessary to illustrate the improvements under the above
second part. 5 is the chamber containing the materials the temperature of which
it is required to raise; 6, chamber from which the converting gases circulate to the
said chamber through the pipe or tube 7; 8, portable furnace resting over the
opening 9 above the pipe or tube 7. The said furnace 8 is constructed with
openings 10 for the passage of air to support combustion. 11, outlet for the
products of combustion; 12, cover; 13, opening through which fuel is fed;
14, handles; 15, bar or boffle plate of brick or other refractory material held at a
short distance from the bottom of the said furnace so as to prevent pieces of
unburned fuel falling in such manner as to obstruct the outlet 11, sufficient space
being left for the products of combustion to pass freely. The outer casing of the
furnace is preferably made of sheet iron, and the lining is prepared by ramming
the said casing with fireclay or ganister, and then cutting away so much of the
said fireclay or ganister as may be needed to make the necessary passages for the
air and products of combustion. The arrows show the direction of motion of
the circulating gases and products of combustion. 8* represents a gas-burning
furnace for use in manner similar to the portable furnace above described. The
combustible gas enters the furnace through the pipe 13*, and air to support
combustion enters through the openings 10*. Outlet for the products of
combustion, 11*.
Third Part. In order to render the apparatus employed in the manufacture of
sulphates more compact, and to minimise the loss of heat by radiation, the apparatus
for drying the chlorides to be converted into sulphates is placed above and between
two lines of decomposing chambers over the hydrochloric acid flue. The salt drying
apparatus is preferably heated by gaseous fuel.
Fig. 14 is a side elevation, and Fig. 15 a plan view illustrative of the above

page_text: tbird head. 16, rows of chambers; 17, endless band and bucket elevator for
raising and depositing the chlorides in the mixing apparatus 17*, whence it falls
on the endless travelling band 18; 19, hydrochloric acid flue; 20, oven through
which the endless band passes, heated by burning gases or products of combustion;
21, apparatus for exhausting the gases from the cylinders.
Fourth Part. To obtain decomposing chambers of large diameter, which shall be
easily constructed and erected, such chambers are made of segments held together
by dovetail pieces. Projections are cast on each segment, enclosing spaces of such
form as to hold one end of the said dovetail pieces. The said projections on each
segment correspond, and are opposite to each other when the segments are in their
places, so that the dovetail pieces may be inserted and hold the segments together.
The spaces enclosed by the projections are increased in area from the exterior to
the interior, and the dovetail pieces are made of greater area at the back than at
the front. The areas of the backs of the dovetail pieces are such that the said
pieces shall only just enter the spaces between the said projections, but when in
position shall leave sufficient space for caulking round the sides, so that the joint
may be made hermetically close, and the passage of air therethrough prevented.
The intermediate parts of the sides of the segments are held together by bolts
inserted through flanges so disposed as to leave caulking spaces.
The covers of the said decomposing chambers are made of pieces held together
by dovetail connections in the manner above described for the segments. The tops
of the chambers and the cylinder formed by the segments are connected together
by grooves and flanges or ribs, spaces being left for caulking.
When sulphate is wanted of great purity and free from iron the sides of the
decomposing chambers and grids are covered with a layer of silicate of soda or
potash applied in solution and allowed to dry.
Fig. 16 is a plan, and Fig. 17 a sectional elevation of a sulphate chamber, the
bottom and top being shown removed, constructed substantially as above; Fig. 18
is a view showing how the bottom, body, and top are fitted together. 22, segments
cast with projections 23, enclosing spaces into which the dovetail pieces 24 arc
fitted; 25, caulking; 26, flanges and bolts; 27, bottom constructed with the
circular groove 28, into which the lower ends of the segments fit; 29, cover, made
with a flange or rib 30, which fits into the groove 28 on the top of the segments.
The covers of the cylinders are made in pieces and joined together by dovetail
pieces and bolts in a similar manner to the segments above described, see Fig. 13;
24, dovetail pieces; 26, flanges and bolts.
Fifth Part. Experience has shown that as decomposing chambers are increased
in diameter, less fuel is required to maintain the materials being treated at the
requisite temperature, and that the manufacture of sulphates is conducted with
greater economy and regularity, but that more labour is required for discharging
the finished sulphate, in consequence of the greater distance through which it must
be moved to enable it to be taken out of the decomposing chamber.
To minimise the above disadvantage passages are so made to the discharge
openings and doors through the walls enclosing the chambers that workmen can
approach close to the material which is to be discharged without entering the
chambers, and barrows or receptacles used in conveying away the sulphate may be
placed against the said cylinders, and the finished sulphate raked directly into the
said barrows or receptacles without being shovelled over the door plates as has
heretofore been necessary.
Fig. 19 is a transverse section, and Fig. 20 a front view of sulphate making
apparatus illustrative of the improvements last above set forth. 16, chambers;
31, enclosing walls; 32, discharge openings or doors; 33, passages through the
walls 31 to allow barrows 35 to be brought close to the discharge openings or
doors 32.
Sixth Part. To further facilitate discharging the contents of decomposing
chambers, the said chambers are constructed with one or more openings in the

page_text: bottoms or floors thereof, and suitable discharge necks are provided to allow the
said sulphates to fall into an arched passage or other suitable space below the level
of the said decomposing chambers. The said passages or spaces extend transversely
or longitudinally from side to side or end to end of the lines of chambers.
The above mentioned discharge necks are attached to the bottoms or floors of
the decomposing chambers, and are closed with upper and lower covers to prevent
air entering the chambers whilst the apparatus is working.
To prevent loss of heat by conduction from the inside of the chambers the space
between the covers is filled with sulphate of soda or other bad conductor of
heat.
The lower cover is hermetically closed by means of a mixture of common salt
and mortar, and is held in its place by screws passing through lugs on the discharge
necks.
The passages or spaces under the decomposing chambers may serve as temporary
magazines for the sulphate, or rails are laid and the sulphate discharged directly
into wagons.
In some cases the sulphate is discharged on endless travelling
bands or plates or on archimedean screws, and thence conveyed or elevated to any
desired place.
Fig. 21 is a sectional elevation and Fig. 22 a sectional plan of sulphate manu-
facturing apparatus, having the discharge necks and passages above set forth
16, chambers; 35, arched passage beneath the chambers and extending across the
apparatus from side to side; 36, discharge necks, shown in detail in Figs. 23 and 24;
37, upper cover; 38, lower cover. The cover 38 is cast with three lugs or
projections 39, which are placed in position over the screws 40 in the lugs 41
secured to the necks 36. The screws 40 serve by means of the lugs 39 to retain
the lower cover against its seat.
Fig. 25 is a sectional elevation and Fig. 26 is a sectional plan of sulphate
apparatus in which the arched passage 35 is shown extending longitudinally
beneath the apparatus, or from end to end thereof.
Fig. 27 is an elevation and Fig. 28 a plan, both in section, of sulphate manu-
facturing apparatus, in which an endless travelling band 42 and an archimedean
screw 43 are shown as means for removing the sulphate from the passage 35.
Any convenient motive power is employed to operate the bands and screws.
desired wagons or barrows may be used to receive the sulphate discharged through
the feed necks.
If
Seventh Part. To prevent loss of heat from the outer walls which enclose the
decomposing chambers, the said walls are constructed with a cavity or cavities
along their length filled with plaster of Paris whilst in the liquid state by
admixture with water. It is preferable that the walls should be built, say, half
a metre in height at a time, and the cavity filled with the aforesaid mixture of
plaster of Paris and water, which is allowed to set hard before the walls are again
built on. Plaster of Paris when dried is an exceedingly slow conductor of heat,
and when so made there is much less loss of heat than with thicker walls when
bricks or stones and mortar are alone used. 43, Figs. 14 and 15, shows the
plaster of Paris portion of the walls.
Having now described the nature of the said Invention in such manner that
others will be enabled to carry out our Invention into practice we claim,
First. Treating sulphurous acid gas substantially in the manner and for the
purposes set forth under the first part.
Second. Apparatus or appliances constructed and operating substantially as set
forth under the first part.
Third. Heating circulating gases in sulphate apparatus substantially in the
manner and for the purposes set forth under the second part.
Fourth. Combining sulphate making and salt preparing apparatus substantially
in the manner and for the purposes set forth under the third part.
Fifth. Constructing chambers substantially in the manner set forth under the
fourth part.

page_text: Sixth. Constructing sulphate making apparatus with discharge passages, sub-
stantially as set forth under the fifth and sixth parts.
Seventh. Constructing the walls of sulphate making apparatus substantially as
and for the purpose set forth under the seventh part.
In witness whereof, I, the said Thomas Robinson, have hereunto set my hand
and seal, this Twenty third day of May, in the year of our Lord One
thousand eight hundred and eighty one.
THOMAS ROBINSON. (L.S.)