Year: 1887

page_text: Date of Application, 23rd Aug., 1887
Specification Accepted, 23rd Sept., 1887.
[Communicated from abroad by ADOLF KAYSER, Chemist, HORACE WILLIAMS and
ALBERT BARNES YOUNG, Gentlemen, all of the City of Buffalo, New York,
United States of America.]
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake and Co. Patent Agents,
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 a pneumatic process for the manufacture of caustic alkali,
carbonates of the alkaline metals and muriatic acid. The principal objects of this
invention are to shorten and cheapen the process of manufacture, to obviate the loss of
sulphur which occurs in the Le Blanc process, and the loss of chlorine which occurs
in the ammonia process, to render the apparatus simple and inexpensive, and to
reduce the skilled labour to a minimum.
It is well known that the reaction of sodium chloride upon clay in the presence of
steam at a high temperature produces muriatic acid gas and a combination of sodium
oxide with alumina and silica. It has heretofore been attempted in various ways to
render this reaction available for the production of salts containing sodium oxide, but
these attempts have not produced useful results principally because the chloride was
converted only in part and because, even if a soluble alkaline salt could be produced,
it was impossible to separate the aluminous and silicious matter from the caustic lye.
It has been proposed for instance, to evaporate the chloride upon a hearth by
generator gases passing over the charge of chloride, and to conduct this vapour
together with steam through a tower charged with silica, clay or other similar
material. By this method the outer portions of the lumps of clay become glazed,
whereby the further reaction of the chloride and steam upon the clay is rendered
impossible.

page_text: In carrying this invention into practice I mix clay, common salt and sufficient
water to render the mixture plastic and mould the same by a suitable brick machine
into cakes or bricks of convenient size, a size of three by two by one and one-half
inches being suitable. These cakes are dried and then placed in a converter of
suitable capacity, the said converter being heated by a current of hot gases passing
through the same. A column of these cakes eight feet high or more, is easily heated
in this manner to a bright red heat, and maintained at this temperature until the
conversion is completed. The reaction of the sodium chloride upon the hydrous clay
is very energetic. Muriatic acid gas is generated long before visible red heat is
reached and the generation of this gas increases rapidly as the temperature rises.
Steam is admitted to the converter with the hot gases as its presence is indis-
pensable after the chemically combined water has been driven off from the clay.
After about six hours the temperature will have reached a bright red heat
throughout the converter, and this temperature is maintained until the conversion is
completed, which usually occurs in from 18 to 24 hours after the proper temperature
has been reached.
The muriatic acid which is generated is condensed and collected in any usual or
well known manner.
'
The converted material so produced I call acid silico sodium aluminate. The clay
and salt are mixed in such proportions that this converted material contains on an
average 33 per cent. of sodium oxide, and is insoluble or only partially soluble in
water according to the temperature at which it was prepared and the composition or
character of the clay employed. It is infusible even at the beginning of white heat,
but the cakes contract and lose their porosity at such temperature while their
composition remains unchanged. For this reason a wide range of temperature
during conversion is admissible provided that a lively red heat is reached and
maintained for a sufficient time.
This acid salt reacts slightly alkaline and is practically insoluble in water, but is
attacked easily by mineral acids; even a digestion with bi-carbonate of soda will
render some of the sodium oxide soluble, but in order to extract the sodium oxide
fully, the following treatment is employed.
I crush the material and smelt it together with a suitable quantity of alkali,
whereby a basic silico sodium aluminate is produced which is very deliquescent and
which yields all of its sodium combinations by lixiviation under development of
considerable heat. I prefer for this purpose, to add to the acid silico sodium
aluminate such a quantity of soda as will raise the total contents in sodium combina-
tions to about 50 per cent. The smelted basic salt is drawn into forms, cobled,
crushed to about nut size, and leached in water. The solution of caustic lye so
produced contains, practically all of the sodium combinations contained in the basic
compound, which combinations consist of from 80 to 90 per cent. of caustic soda, the
rest being sodium carbonate and silico aluminate of sodium. This caustic lye may be
directly employed for industrial purposes, for instance in the manufacture of soap.
The undissolved residue which I call regenerated clay consists of clay which has
almost the same composition as the clay originally employed.
This basic silico sodium aluminate should contain about 50 per cent. of sodium
oxide in order to permit of a speedy and complete lixiviation. When the percentage
of sodium oxide is much less than 50 per cent., the solid undissolved matter is hard,
little porous and penetrated with difficulty by the water.
When the percentage of sodium oxide is much in excess of 50 per cent., the solid
matter assumes the form of slush or soft mud which renders the lixiviation and
complete separation of the caustic liquid from the solid matter impossible. When the
percentage of sodium oxide is about 50 per cent., the material, upon being placed in
water breaks up into small chips, splinters or fragments by numerous cracks
extending through the lumps, which chips or fragments facilitate the thorough
permeation of the mass by the water, and are still sufficiently solid and bulky to
permit of their easy separation from the lye or liquid.
When the basic silico aluminate is subjected to the process of lixiviation but a small

page_text: quantity of floculent matter is produced which consolidates by molecular attraction
into gelatinous masses. The latter adhere to the splinters or chips of solid matter
here and there without interfering with the operation of lixiviation.
The regenerated clay so recovered, is specifically lighter than the original clay and
whiter in colour, as it has lost its iron, but this regenerated clay, which has the
hardness of soft slate, answers all the purposes of the original clay and is used
repeatedly, only such quantities of fresh clay being added from time to time as may
be necessary to compensate for loss by manipulation.
If the clay employed in this process contains lime and magnesia salts in appreciable
quantities, such salts will accumulate by repeatedly using the clay until the excess
of these salts finally present in the regenerated clay necessitates the renewal of the
clay.
The caustic soda and sodium carbonate are obtained from the solution in any suitable
manner which depends upon the character of the desired ultimate product.
Clay, being a hydrous aluminum silicate, acts upon the sodium chloride very
energetically and at a comparatively low temperature.
It is desirable that the proportion of silica to alumina in the clay employed should
be about as two to one, because, although other proportions do not materially affect
the conversion in producing an acid salt, the proportion stated facilitates the subsequent
treatment of the converted acid salt and the climination of the silica and alumina from
the sodium combinations. When the clay contains more than the above proportion
of alumina, the acid salt resulting from the conversion requires more alkali and a
higher temperature to render it soluble and the regenerated clay is slushy and cannot
be separated from the caustic lye. When the clay contains silica in excess of the
above proportions, the silica is not sufficiently protected by alumina during the
process of leaching and the lye is richer in the constituent elements of the clay and
the latter will also be more slushy.
Clay of the composition above pointed out is seldom found and in order to meet the
requirements of this process I prepare a clay of the desired composition by adding or
removing sand therefrom, by washing or otherwise, as may be necessary.
This elimination of both silica and alumina during the leaching of the basic salt is
an important feature in the manufacture of soda from the silico sodium aluminate.
The silica combines with the alumina in status nascens while at the same time water
enters the combination, forming hydrated aluminium silicate and sodium hydrate.
At the beginning of the manufacture, the necessary quantity of soda must be
supplied to render the first converted acid salt soluble. Afterwards a proper quantity
of the tank liquor or solution is added to the acid salt instead of soda, and the
mixture is evaporated to dryness and smelted upon a suitable hearth preparatory to
leaching.
The accompanying drawing represents a sectional elevation of the apparatus which
1 preferably employ.
A represents the gas generator which may be of any suitable construction and
which is charged with coal, coke or other suitable fuel. a represents the pipe by
which steam is supplied to the generator. represents the pipe by which the gas
escapes therefrom. C represents a fan blower or other apparatus connected with the
gas pipe b. d represents the discharge pipe of the fan C, and D represents the com-
bustion chamber into which the gas is delivered by the pipe d. e represents a pipe
by which a blast of air is delivered from a fan blower E or other suitable apparatus
into the combustion chamber D for burning the gas in the same. F represents the
converter connected near its top with the combustion chamber D by a pipe f, through
which the hot gases pass from the combustion chamber to the converter. The latter
is provided at its top with a feed opening g having a removable cover G and at its
lower end with a discharge opening h and a movable bottom H. 1 represents a pipe
connecting with the lower portion of the converter, and through which the waste
gases escape from the same and pass to the condenser in which the muriatic acid gas
is condensed. When two or more converters are used in a battery, the gas

page_text: exit pipe I of one converter is connected with the gas inlet of the next following
converter.
While I recommend the employment of this apparatus, I do not wish to confine
myself to the same as it may be modified without departing from the spirit of my
invention.
The gases which enter the converter should contain a sufficient quantity of steam,
to furnish hydrogen for combination with the chlorine, and an excess of oxygen to
prevent the formation of carbon monoxide and the reducing action resulting there-
from. These gases permeate the entire charge in the converter and effect a complete
conversion of the sodium chloride as above described. These gases act not only as
the heating agent in the converter, but facilitate by diffusion the formation muriatic
acid acting even more energetically than superheated steam alone. The material of
which the cakes are composed is thoroughly heated to the high degree required for a
complete conversion and brought in contact with the hydrogen and oxygen required
for the conversion.
When it is desired to produce the corresponding potassium salts, I substitute an
equivalent quantity of potassium chloride for the sodium chloride in the herein-described
process.
Having now particularly described and ascertained the nature of the 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.
First. The herein described method of converting the chloride of sodium or potassium
into its oxide, which consists in mixing the chloride with clay, and heating the mixture
in a converter directly by passing highly heated gases containing steam through the
converter, substantially as set forth.
Second. The herein described method of obtaining the oxide of sodium or potassium
from the chloride thereof, which consists in mixing the chloride with clay, heating the
mixture in a converter directly by passing highly heated gases containing steam through
the converter, smelting the converted material together with an alkali, and then
extracting the sodium or potassium combinations by lixiviation, substantially as set
forth.
Third. The herein described method of obtaining muriatic acid which consists in
mixing the chloride of sodium or potassium with clay, heating the mixture in a
converter by passing highly heated gases containing steam through the converter, and
condensing the muriatic acid gas which is generated, substantially as set forth.
Fourth. The herein described acid silico-aluminate of sodium or potassium,
substantially as set forth.
Fifth. The herein described basic silico aluminate of sodium or potassium, sub-
stantially as set forth.
Sixth. The herein described regenerated clay, substantially as set forth.
Seventh. The herein described caustic lye, substantially as set forth.
Dated this 23rd day of August. 1887.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.