Improvements in the Manufacture of Caustic Alkali, Carbonates of the Alkaline Metals and Muriatic Acid, and of Bricks, Cakes, or Blocks for use therein, and Apparatus therefor.
Year: 1891

page_text: Date of Application, 16th June, 1891-Accepted, 10th Oct., 1891
COMPLETE SPECIFICATION.
[Communicated from abroad by THE KAYSER PATENT COMPANY, of No. 1,
Exchange Place, Jersey, State of New Jersey, United States of America,
Dealers in Patents.]
Improvements in the Manufacture of Caustic Alkali, Carbonates of
the Alkaline Metals and Muriatic Acid, and of Bricks, Cakes, or
Blocks for use therein, and Apparatus therefor.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co. Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 :-
This invention relates to the manufacture of caustic alkali, carbonates of the
alkaline metals and muriatic acid and bricks cakes or blocks for use therein and to
apparatus therefor.
In the accompanying drawings
Figure 1 represents a cake of material with which my process starts.
Figure 2 is an elevation of the drying apparatus and the converting furnace and
apparatus for disposing of the muriatic acid gas.
Figure 3 is a plan view of the converting furnace and various passages connected
therewith.
Figure 4 is a vertical section through the line x x of Figure 3.
Figure 5 is a horizontal section through the line y y of Figure 4.
Figure 6 is a horizontal section through the line 2 z Figure 4.
Figures 7, 8 and 9 are details.
The material which is used at the commencement of the process consists of blocks,
bricks or cakes preferably of the form shown in Figure 1.
These bricks or cakes are made from clay and salt, the clay containing silica and
alumina. I have found that in determining the form and constituents of these cakes
or bricks, the following considerations are of primary importance:
They should not cinder at the beginning of white heat to which temperature I
now prefer to raise the contents of the converters. A cindered glassy lump of acid
salt, semi-fluid at the elevated temperature of the converter does not increase
perceptibly the yield of Na₂O even under otherwise favorable conditions due to the
reduced surface it presents to the acting gases. There are moreover mechanical
difficulties in emptying a converter filled with a cindered mass because it becomes
packed together in a solid lump which is very doughy while hot and can only be
removed after cooling by being cut out in lumps.
It is well known in metallurgy that alumina is very refractory; therefore, by
increasing the percentage of alumina in the bricks or cakes, I have been able not
only to produce an acid salt yielding a high percentage of Na,O, but a brick or
cake which will preserve its porous shape and also its refractory properties at the
beginning of a white heat. But an excessive increase in the proportion of alumina
to silica must be avoided for the reason that the mixture would during the process
become so pulverulent as to fill the interstices between the blocks in the converter
with its own dust or crumble away under its own weight in the kilns. Even if it
were not open to these objections, it would prove too refractory in the "opening
furnace, and silica would have to be added to produce a well-opened, uniformly
melted basic salt.
"
I have found that the most satisfactory composition of clay for the manufacture
of cakes or bricks is one containing alumina and silica in substantially the proportion
of one and one half pounds of silica to one pound of alumina. The acid salt made
from this composition contains from 31 to 33%. Na,O is perfectly refractory at the

page_text: beginning of a white heat; the blocks are solid; will roll out of the converter ut
once when the bottom plate is removed; they make but little dust when handled
and none while being converted; they stand the crushing action of their own weight
and there is no need of silica when smelting them into basic salt.
To this composition, salt is added, preferably ground rock salt, being less
voluminous than evaporated salt and producing very compact and heavy raw
blocks. Aside from this advantage, it is frequently purer than the latter, contain-
ing less sulphates which are not totally destroyed in the subsequent manipulations.
There is no positive necessity to reduce the salt employed to a very fine grain, but
it should be fine enough, not to impair the plasticity of the material to be easily
handled by the block brick or cake machine.
The consistency of the pasty mass composed of clay and salt before it is presented
to the block mill, should be as tough as possible; thereby heavy blocks are
produced and the largest amount of material is concentrated in the smallest volume,
reducing the surface exposed to the subsequently converting action of the gases.
By that means also the blocks or cakes when they leave the block machine are
harder and thereby protected from being defaced or deformed in the subsequent
handling.
In determining the form of the blocks or cakes, I have found that two con-
siderations are of primary importance:
1. It has been found that some salt will be evaporated during the process under
all circumstances and that this evaporation increases directly with the surface
presented to the gases. One object therefore is, to reduce such evaporation by
presenting a limited surface to the gases.
The
2. On the other hand, where the blocks of materials are too thick and present a
small extent of surface, the process takes a longer time and the central portions of
the blocks frequently retain an undue amount of undecomposed NaCl.
converting gas meets the evaporated NaCl within the pores of the material and
the diffusion of these gases is slower the longer the way that they have to travel.
:
I secure the desirable extent of surface by channelling the blocks and prefer to
mould them as shown in the accompanying drawings, viz. cylindrical, three inches
in diameter and four to five inches in length with a central hole or channel one
inch in diameter. This form secures a radial thickness of material everywhere of
about one inch and at the same time the form is such as to maintain itself well
throughout the subsequent operations. The channel also produces so much more
gas way through the mass of blocks in the converter.
After being moulded the blocks or cakes are dried at a temperature of at
least 220° F., but in this operation care should be taken that the temperature be
raised gradually to prevent the cracking of the cakes. The effect of this drying
operation is to drive off the mechanically held water and to harden the cakes
preparatory to their introduction into the converters. This drying is accomplished
in the dryer shown in Fig. 2.
1 is a furnace into which trucks carrying the baskets 2 are run at one end and
out at the other end. Doors 3, 4 are provided at each end so that the furnace can
be closed and the hot air is introduced by the flue 5 and taken away by the flue 6.
A series of trucks are employed so that a batch of the cakes can be introduced at
the receiving end 3 as fast as a previous batch is finished and removed at the
delivery end 4, which will occur about every hour. The temperature of this drier
at the hot end, should not be less than 220° F., but may be increased to 250°.
The hot air travels from the delivery end to the receiving end and the cakes first
introduced are thereby gradually heated. It is important that the cakes should be
gradually heated to avoid cracking.
The effect of this drying is to remove the mechanically held water from the cakes
and harden them sufficiently to withstand the subsequent handling.
The next step in the process is to introduce them into one of the converters 7, 8,
9 or 10 each of which is cylindrical near the top and sufficiently conical toward the
bottom to allow the whole charge to roll out and at the same time direct the gases

page_text: throughout all the lower part of the mass. Each converter has a charge opening 11
at the top and a discharge opening 12 at the bottom. The cakes should not be
dumped roughly into the converter but should be placed therein gently to avoid
breaking and pulverizing, since an important feature of the process is the maintain-
ing of the individual cakes forming the contents of the converter intact which,
owing to their size and shape, will maintain passages for the entrance of the gases
to all parts of the mass providing these passages are not filled up by dust or fine
particles resulting from the crumbling of the cakes. In charging the converter I
therefore proceed as follows:
The cakes are dumped upon the floor 13 above the converters and the contrivance
shown in Figure 7 is utilized. This contrivance consists of two cylindrical or
slightly conical sections 15 and 16. The section 15 is provided with a trap-door 17
closing the bottom opening and held in place by a latch 18 operated from above by
the chain 19. The section is also provided with the side doors 20 and 21 at
different elevations and at the top is provided with means of attachment to
section 16, which latter section is also provided with two side doors 22 and 23, at
different elevations. The means of attachment or connection between the sections
may be of any suitable construction. As shown, they consist simply of bolts 16*
hinged to the top section, and arranged to swing into notches in the top flange of
the bottom section, their ends being provided with nu's 16. Detached from the
section 16, the section 15 is first suspended in the charge opening of the converter
as 9 by the yoke 16 or otherwise from the crane 14 so that the door 20 is at
convenient height for the introduction of cakes, and the cakes are introduced
through the door 20 to as high a level as possible; then the section 15 is lowered
until the door 21 is at a convenient height above the floor 13, and as many more
cakes are introduced as possible. Then the section 15 is again lowered until its
top portion is at a convenient height and completely filled with cakes. The
section 15 is then sustained temporarily by bars laid beneath its top flange and
resting on top of the retort and yoke 16 is attached to the top section 16, then the
section 16 is placed on top of and secured to the section 15 and the like operation
is repeated through the doors 22, 23 of section 16, thus filling the two sections
nearly to the top, by which time the bottom of the section 15 will have descended
to near the bottom of the converter and thereupon the door 17 is released from the
latch 18 and the cakes allowed to slide out at the bottom of the converter; then the
contrivance is raised, and as each successive door comes at a convenient height
above the floor 13 it is again filled with cakes up to that level. When the
contrivance has been lifted entirely out of the converter, the converter will be so
near full that the cakes necessary to complete the charge may be introduced
directly from above. When the charging is complete the top level of the charge
will be below the level of the entrance of the heating or converting gases.
It will be convenient to next describe the provision for heating the converters
and removing the products therefrom.
Fuel gas is brought from a generator through the pipe 24 and the cooler 25 and
pipe 26 to the gas forcing apparatus 27, whence it is forced into the pipe 28 running
nearly all around the furnace. The cooling is simply to protect the gas forcing
apparatus from undue heat. The branches 29, 30, 31 and 32 lead from this pipe,
respectively to passages 33, 34, 35 and 36 which communicate with the tops of the
respective converters at angles nearly tangential to the peripheries thereof. The
introduction of the converting gases into the vacant space above the top of
the charge and in a tangential direction is advantageous in that the gases are given
a circulatory motion, thoroughly mixed, and distributed around the circumference
of the converter chamber, so that in sinking they permeate all portions of the
charge and thus effect a thorough and uniform heating of the same. From the
passages 33, 34, 35 and 36 respectively, vertical passages 37, 38, 39 and 40 extend
downward through the walls of the furnace until they communicate respectively by
the passages 41, 42, 43 and 44 with the circular passages 45, 46, 47 and 48 surrounding

page_text: the bottom of the several converters and receiving the gas discharged therefrom.
Then the passages 37, 38, 39 and 40 extend still further down until they all connect
with an underground passage 49. They are each provided with a damper 50
between the passage, as 33, connected with the top of one converter, and the
passage, as 44, connected with the bottom of the next converter. Each is also
provided with a damper 51 between the last named passage and the underground
passage.
52 is a by-pass pipe extending around the gas forcing apparatus 27 and provided
with a weight controlled valve 53 by the adjustment of which the pressure of gas
supplied to the converters can be controlled. A valve is placed in each of the
pipes 29, 30, 31, and 32 at 54, so that the supply of fuel can be cut off from either
of the converters as desired.
55 is a fan or air forcing apparatus which forces air into the pipe 56 (shown
broken off in Fig. 3) extending around above the pipe 28 and provided with branch
pipes leading to the pipes 57, 58, 59 and 60), which discharge the air into the
passages 33, 34, 35 and 36 respectively, where it mingles with the gas discharged
therein as already described. 61, 62, 63 and 64 are covers for holes leading from
the floor above the converters down into the passages 37, 38, 39, 40 respectively.
65, 66, 67 and 68 are steam pipes discharging steam into the passages 33, 34, 35
and 36 to mingle with the air and gas therein. The converters are all lined with
fire bricks as are also the covers of the charge openings 69, 70, 71 and 72.
It will be observed that each of the vertical passages 37, 38, 39 and 40 connects
at its bottom with one adjacent converter and at its top with the other so that by
the proper arrangement of the dampers, the bottom of each converter may be con-
nected with the top of its neighbor throughout the whole series; or by another
arrangement of dampers this connection may be broken and the bottom of any one of
the converters may be connected directly with the underground passage.
The passage around the lower end of each converter, as the passage 45, is com-
municated with from the interior of the converter through a series of radial openings
between the separated fire bricks 73; thus constituting a perforated ring between
the interior of the converter at the bottom and the passage, as 45, surrounding the
same. 74 is a plate closing the discharge opening of the converter, being held in
place by the hangers 75 and the cross bars 92 and also being supported on the
points of screws 76 (shown beneath converter 10, Fig. 4) which are mounted in the
cross bars 78 adapted to slide as a carriage on the guideways 79, and thus form a
ready means for the removal of the heavy plate to one side for the discharge of the
converter. The plate 74 is provided with tap holes 93 and with a central
opening 80 covered by a supplemental plate 81 held in position by suitable hangers
as 82 and the cross piece 87. 83 are archways below the converters into which
their contents are discharged and from which they are removed for subsequent
operations.
The manner in which the converters are operated may be described as follows:
The product of the combustion of the fuel gas employed must be slightly
oxydizing in order to avoid any loss of sodium by reduction, an action which
becomes more likely the more basic the cinder. This is within the control of the
operator by the devices already described enabling him to regulate the relative
quantity of gas and air employed.
It is very important to have a fuel gas of the highest pyrometrical effect.
Common generator (producer) gas, containing a large percentage of nitrogen, is
necessarily of a limited pyrometrical effect. Heating the air used for the com-
bustion will help a great deal in elevating the temperature, but it is better yet to
use natural gas, where it can be had at a reasonable cost or to use water-gas alone
or mixed with generator gases.
Four converters are combined in a set. The arrangement of the flues as described,
is such that each of them may be worked independently or with the following
in order.

page_text: The converter 7 having been
steam are introduced into the
gas therein ignited through an
charged, the proper proportions of gas, air and
passage 33 by opening the suitable valves, and the
opening in the floor above.
The flame and products of this combustion enter the vacant space in the top of
the converter chamber in a tangential direction and with considerable velocity, this
tangential admission of the gases being followed by the uniform heating of the
entire charge to a white heat for the reasons already pointed out.
During the treatment of the charge in the converter, the opening 80 in the
bottom plate enables the operator to clear away any obstructions which may block
the gas ways at the bottom; and tap holes 93 two inches in diameter are provided
to drain away any salt previously condensed which may descend as a liquid to the
bottom of the converter and which if allowed to remain would solidify there and in
the flues and thus choke up the passages for the escape of the gas and create a
solid mass in the bottom of the converter which upon cooling would entirely pre-
vent the discharge of the contents of the converter and render the process almost
inoperative. These tap holes are used successively and the melted salt is therefore
discharged several times during the preparation of each charge in the converter.
While in use the bottom plate is covered with three or four inches of dust and the
central opening as well as the tap holes are closed. About four days will be
required to complete the conversion.
When the operation in converter 7 is complete the bottom plate is removed and
the finished incandescent salt falls through the opening and is removed. As soon
as the temperature permits, the bottom plate is replaced again and the converter is
ready to be recharged.
Pending the conversion in converter 7 the other converters will be charged suc-
cessively, one each day, and when in continuous operation they will be worked in
series as follows:
Suppose the contents of converter 8 to be at a perfect white heat and the
operation therein to be almost complete. The material under treatment now
produces but little muriatic acid. The highly incandescent gas from converter 8
therefore, is not conducted to the underground flue, but by regulating the dampers 50
and 51, is conducted into the top of converter 9 (also at a white heat at the top
but still at a red heat at the bottom) where it mingles with new fuel gases in order
to establish the required temperature and where the vaporized salt which it contains
is utilized and converted. And from this converter 9 the gases of both 8 and 9
descend into the underground flue to be removed by the exhaust. In the meantime
converter 10 having been charged only the day before, is worked independently
from the others. Though red heat may have been established at the top of its
contents, it is comparatively cold below and is not yet fit to receive the gases from
converter 9 since the lower and colder strata would condense the salt contained in
those gases and this would obstruct the gasways.
On the next day, however, the converter 7 has been charged and set to work;
converter 8 has been finished and discharged; converter 9 is at a white heat and
sends its gases (hot but weak in acid) to converter 10, and converter 7 is run
independently of the others.
Thus each day one converter is charged and one discharged and the operation
is practically continuous providing no interruption happens in any one of the con-
verters. The principal causes of interruptions which this construction of apparatus
and process obviate would arise from a faulty composition of the clay. If the
clay contains an excess of silica the cakes or bricks will under the high temperature
employed become glazed or cindered. If on the other hand they contain an excess
of alumina, they will disintegrate and obstruct the passage of the gases. In either
case the converting action will be stopped or seriously impeded.
Care should be taken to increase the temperature slowly of a newly filled con-
verter so as to avoid the volatilization of salt while the cakes at the bottom are
comparatively cold. As soon as a red heat is established at the bottom of the
converter however, no further obstruction from this cause will be had and the

page_text: temperature is now increased as rapidly as possible to beginning white heat so as
to produce the acid reaction of the silica and alumina. A certain amount of salt
sublimated to the bottom of the converter during the earlier part of the process
will then smelt and will be tapped consecutively through the holes in the bottom
plate. I use the series of tapping holes, extending downward through the bottom,
for the reason that when a hole is tapped it becomes filled with the salt so that it
cannot be reopened, thus necessitating the tapping of another hole when it is again
required to draw away the melted salt.
The advantages attending the use of the high temperature and percentage of
alumina which I have described are First. A much more rapid conversion.
Second. A much richer acid salt. Third. The elimination of nearly all the sodium
chloride which might otherwise be present. Fourth. The possibility of using a
highly heated aluminous compound which allows a considerable increase in the
percentage of sodium acid in the acid salt. Fifth. The production of a greater and
a stronger acid. Sixth. A more efficient and economical employment of the fuel.
Seventh. The uniform reduction of the entire charge in the retort. Eighth. A
cleaner and more efficient operation as the higher temperature prevents the precipi-
tation of the sodium chloride in the lower part of the apparatus.
The acid salt (sodium silico-aluminate) is converted into the basic salt by the
addition of alkali, by melting either with raw lye or its equivalent of soda ash.
If raw lye is used the carbonic acid from the combustion of fuel gas first
transforms the caustic alkali into carbonate until a temperature is reached where
carbonic acid is displaced again by the acids silica and alumina and escapes.
The elimination of carbonic acid can only be accomplished when the temperature
of the furnace and the percentage of sodium oxide are balanced. To reach this
end more readily, I prefer that the basic salt should contain from 40 to 42 % of
sodium oxide, because with this percentage a lower temperature answers the
purpose and the operation then acts less destructively on the lining of the furnace
than the more highly alkaline cinder.
The basic salt resulting from the melting operation is next crushed to a chestnut
size and is leached systematically until the lye shows about one degree Beaume.
The insoluble remainder is hydrous sodium silico-aluminate with from 17 to 20%
of sodium oxide. This is then ground and floated and decomposed by quick lime
or carbonic acid. If quick lime is employed for this purpose the operation is con-
ducted as follows:
The ground and floated hydrous sodium silico-aluminate is treated with a slight
excess in equivalent of lime; avoiding too large a volume of liquid in relation to
the solid matter which by interfering with contact would prevent speedy action
(I have found a creamy consistency of the material to be the most convenient).
This reaction can be accomplished cold, but I prefer to accelerate it by boiling,
which assists at the same time in mixing the ingredients perfectly and also in
causing the residue (hydrous calcium silico-aluminate) to subside and separate clear
from the caustic lye. The speed of the operation depends on the fineness of
the grain. The digestion should be carried on until all the soda is displaced by
lime.
The lye so produced will be found perfectly pure, of a gravity from 4° to 5º B.
It is conducted back to the leaching tanks and there used for leaching a fresh
supply of basic salt.
This lye is preferably separated from the residue (hydrous calcium silico-
aluminate) in a filter press which is provided with a washing arrangement to
perfectly exhaust it. Employing a pressure of 75 pounds, cakes are produced
which are found to contain about 40% of water. The same material leached in
filter tanks would contain on an average 80% of water and is very difficult to
handle or dry.
This residue upon exposure to the air is decomposed by the carbonic acid of the
air; producing a body composed of calcium carbonate of silica and alumina in the
finest division.

page_text: This body is, I am confident, an entirely new article and is capable of many
practical applications. Being extremely fine it can be used with advantage as a
base for glaze, as a flux with kaoline for stone ware and again for hydraulic cement.
It is eminently fitted as a substitute for infusorial earth. It is remarkably
pulverulent and is furthermore distinguished by containing a very large percentage
of chemically bound water when air dried (say 30 %).
As a modification it may be found convenient to reduce the basic salt without
previous leaching and treat it with the required amount of lime and the like. By
so doing the separate lye will be found pure and free from silica; the tankage for
the leaching of the crushed basic salt is done away with while more power is
required for the grinding.
If carbonic acid is employed for decomposing the hydrous sodium silico aluminate
it (in aqueous solution) acts instantaneously upon this substance, if finely divided,
forming a solution of sodium carbonate.
I will next describe the treatment of the muriatic acid gas after its discharge
from the converters into the underground passage 49, as already described.
Great difficulties were encountered in eliminating the salt from the acid gases
produced in the converters the presence of which salt is due to the elevated
temperature employed. But I have discovered that such gas can be purified by
passing it through small channels where it coats the walls with salt like frost; and
to utilize this discovery, the gas which is exhausted by the fan 84 is forced through
the pipe 85 into a small tower 86, the area of which is dependent upon the volume
of gas to be sent through.
This tower is filled with a substance 97 presenting condensing surfaces, such as
coke, through which the gas disseminates and upon which it deposits and leaves
the salt; passing out into the passage 88 in a purified condition. 89 is a water pipe
which is employed when the tower is not in use to wash out the salt which has been
deposited.
From the pipe 88 the gas is passed through a series of coke towers 90, 91
wherein it is caused to be condensed in a well known manner.
In lieu of sodium chloride with which my process starts I may employ as an
equivalent any of the chlorides of the alkaline metals.
The following process may also be used for the direct and economical conversion
of the insoluble sodium-silico-aluminate or acid salt resulting from the treatment
in the first converters into a soluble sodium-aluminate, so that the sodium salt and
the alumina may be readily separated, and at the same time, if desired, a residual
product valuable in the manufacture of water lime obtained.
I combine finely powdered acid salt with finely divided lime in the form of
calcium carbonate, calcium oxide, or calcium oxy-hydrate in approximately equal
and equivalent proportions. I heat this mixture to a decomposing temperature in
a reverberatory furnace or otherwise, as may be found most convenient. This
temperature, which must be determined by observation or otherwise, in each case,
depends, I find, on the temperature at which the acid salt was produced, but it
ranges from a sharp red to a high white heat. The temperature must be as high
or higher than that under which the acid salt was produced. When the required
temperature is reached the reaction is nearly instantaneous, the sodium chloride
present being eliminated by vaporization. The sodium oxide of the silico-
aluminate is replaced by the lime and the oxide unites with part of the alumina
and produces sodium-aluminate. The new product, a soluble sodium-aluminate,
and a calcium-silico-aluminate, remains in a pulverulent condition and is next
leached with water. The resulting lye is a very pure solution of sodium-aluminate,
and the residue practically free from sodium salt, in calcium-silico-aluminate. The
solution of sodium-aluminate so obtained contains a valuable amount of alumina,
depending on the quality of the lime employed, and being variable at the will of
the operator.
If calcium-carbonate or calcium-oxide is employed as mentioned above, the lye
will contain the maximum amount of alumina. The minimum amount of alumina

page_text: is obtained. when slacked lime is employed, or lime in any of the above forms, in
large excess.
If sodium-carbonate and alumina are to be produced from the sodium-aluminate
solution, the latter is treated with carbonic acid in known ways, the result being
sodium carbonate and practically pure alumina, which latter is a valuable product
for use in chemical processes.
If
pure caustic lye is to be produced, milk of lime may be added either to the
leaching fluid or to the solution the effect being to cause the precipitation of
insoluble calcium-aluminate in a manner well understood by the skilled chemist.
In my process I am enabled to dissolve a very large part of the alumina from
the acid salt, from sixteen to eighteen per cent. being obtainable as against twelve
to thirteen per cent., the limit under the ordinary mode of production from
Kryolith.
The residual calcium-silico-aluminate is an excellent material for hydraulic or
water lime. Having in view its production for this purpose I use, in the first
instance an amount of lime, in either of the forms stated, sufficient to establish the
correct proportions between the acid (silica and alumina) and bases (calcium and
magnesium) and avoid the necessity of a subsequent mixing.
The cakes of calcium-silico-aluminate, as delivered from the filter press, should
at once be subjected to a drying and calcining process before the carbonic acid of
the atmosphere has time to decompose the calcium salt.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed as communicated to me
by my foreign correspondents I declare that what I claim is :-
1. The herein described method of producing an alkaline oxide, which consists
in mixing the chloride with clay containing silica and alumina in approximately
the proportions of one and one half pounds of silica to one pound of alumina and
heating the mixture to a white heat in a converter by passing highly heated gases
containing steam through the converter, substantially as described, whereby the
conversion is accomplished without materially cindering or pulverizing the
charge.
2. The herein described method of producing an alkaline oxide, which consists
in mixing the chloride with silica and sufficient alumina to render the mixture
refractory at a white heat, and heating the mixture to a white heat in a converter
by passing highly heated gases containing steam therethrough.
3. The herein described method of treating an alkaline chloride, which consists
in heating a mixture of the chloride with clay by passing highly heated gases of
combustion and steam through the same, then combining with the resulting gases
additional highly heated gases and applying this combination directly to heat a
second mixture of the chloride with clay; whereby economy of heat is secured
and the vaporized salt resulting from the first operation carried over and
decomposed by the second operation.
4. The herein described method of treating an alkaline chloride which consists
in heating a mixture of the chloride with clay by the direct action of highly heated
gases, thereby producing an acid silico aluminate of the alkali, then smelting the
same with an alkali, and decomposing the basic salt thus produced, substantially as
described.
5. The herein described method of treating an alkaline chloride which consists
in heating a mixture of the chloride with clay by the direct action of highly heated
gases, then smelting the product with an alkali, then floating the same in a finely
divided state, and then decomposing, substantially as described.
6. The herein described method of treating an alkaline chloride, which consists
in heating a mixture of the chloride with clay by the direct action of highly
heated gases, then smelting with an alkali, then decomposing, then filtering the
product of the decomposition, substantially as described.
7. The herein described method of treating an alkaline chloride, which consists

page_text: in heating the mixture of the chloride with clay by the direct action of highly
heated gases, then smelting with an alkali, then leaching, then grinding the
residue and then decomposing so as
to release the alkali, substantially as
described.
8. In an apparatus for treating alkaline chloride a converter provided with a gas
inlet at the top and with a series of circumferential gas outlets at the base,
whereby the distribution of the gas and the uniform heating of the charge
are secured.
9. In an apparatus for treating alkaline chloride a converter provided with a
tangential gas inlet at the top and a series of circumferential gas outlets at the
base, substantially as, and for the purpose described.
10. In an apparatus for treating alkaline chloride a converter having at the base
circumferential gas outlets, and tap holes extending down through the bottom.
11. In an apparatus for treating alkaline chloride in combination with a series
of converters, a passage to receive the generated gases from all, an exit passage
provided with a damper from each converter leading thereto, and a passage
provided with a damper leading from the last named passage to the adjacent
converter; whereby the generated gases from each converter may be discharged
either into the first named passage or into the adjacent converter substantially as
described.
.
12. As a new article of manufacture a rigid porous cake for use in the
manufacture of caustic alkali and the like, composed of salt, silica and alumina,
whereby it is adapted to withstand a white heat without cindering or disintegrating
and channelled in order to reduce its thickness and permit the gases to permeate
all portions of its interior.
13. As an article of manufacture a tubular cake refractory at white heat,
composed of salt with silica and alumina in approximately the proportions of one
and one half pounds of silica to one pound of alumina.
14. The process of manufacturing sodium-aluminate from insoluble silico-sodium-
aluminate, consisting in subjecting a mixture of the silico-sodium aluminate and
lime to a decomposing temperature.
15. The process consisting in subjecting a mixture of silico-sodium-aluminate
and lime to a decomposing temperature and then leaching the resulting product.
Dated this 16th day of June 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.