Improvements in the Manufacture of Alkaline Carbonates and Bye-products, and in Arrangement of Plant therefor.
Year: 1890

page_text: Date of Application, 19th July, 1890
Complete Specification Left, 20th Apr., 1891-Accepted, 23rd May, 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Alkaline Carbonates and
Bye-products, and in Arrangement of Plant therefor.
We, ARTHUR GEOFFREY HADDOCK of Church Road, Halewood, in the County
of Lancaster, Fellow of the Institute of Chemistry, and JOHN LEITH, of The
Grove, Knowsley Road, St. Helens, in the same County, Manufacturing Chemist,
do hereby declare the nature of this invention to be as follows:-
:-
This invention has for its principal object a process of manufacturing alkali,
embracing to a considerable extent the advantages of the ammonia soda process
and the Leblanc process, the hydrochloric acid being largely saved, Leblanc alkali
waste profitably utilised and useful bye-products, such as pearl hardening and
sulphuretted hydrogen, obtained, while, by one variation of our process, the use of
ammonia is entirely obviated.
The fallin
decaxintion of the proces OR
worked out experimentally

page_text: sulph-hydrate when pure hydrated calcium sulphate or pearl hardening will be
obtained. It is filtered off, washed and dried for sale.
As an alternative method, pearl hardening may be made by adding to the solution
of calcium sulph-hydrate, made as described, a strong solution of salt cake (sodium
sulphate) when a precipitate of pearl hardening will separate, and a solution of
sulph-hydrate of soda will be formed, which can be settled or filtered off. The
sodium sulph-hydrate may be sold as such, or used for liberating ammonium sulph-
hydrate from salts or liquors containing ammonia, or for obtaining bicarbonate
of soda direct without the aid of ammonia in the following modification of the
process:-
The sulph-hydrate of sodium solution is made (by concentration if necessary) of
such strength that it contains 26-20 per cent. sodium sulph-hydrate, equivalent to
14.5 per cent. alkali (Na,O).
This solution is placed in Solvay's or other ordinary carbonators, in series, and
carbonic acid gas (kiln gas containing 25 per cent. to 30 per cent. CO, and without
free oxygen) is pumped through until the alkalinity (tested in a cooled portion of the
solution) drops to an amount equal to 3.4 per cent. or 3.6 per cent. Na,O. The
solution of sodium sulph-hydrate may be treated in the carbonators at the ordinary
temperature, or may be heated to about 140 degrees Fahrenheit. In the latter
case, the reaction is more complete, and the sodium bicarbonate which falls is in a
more compact form and can be more perfectly separated from the mother liquor at
the end of the operation.
The following reactions take place in the carbonators •

page_text: The sulphuretted hydrogen evolved in the first equation (except a constant
circulating quantity required to make calcium sulph-hydrate) is subjected to partial
combustion and sulphur obtained by processes well known.
The calcium sulph-hydrate solution is made by passing a portion of the
sulphuretted hydrogen evolved from the carbonators direct through a series of
vessels containing calcium sulphide (Leblanc vat waste) in suspension, as protected
by Mr. Leith in Specification No. 8942 of 1890.
An alternative method of making calcium sulph-hydrate is as follows:-
Native or other sulphate of calcium may be calcined in a closed furnace with
coal or other carbonaceous material, when sulphide of calcium will be formed.
The resultant mass made into a magma with water could be used instead of
Leblanc vat waste.
Native or other sulphates of barium or strontium may be treated by calcination
with carbonaceous material as above, and used instead of Leblanc alkali waste.
In this case, we get a production of barium or strontium sulphate in the place of
pearl hardening.
We hope to secure the following advantages by this process, few of which are
common to any
other alkali process at present in operation :-
Lime for sale is obtained from the burning of the limestone, instead of having to
use it in the still. The recovery of sulphur from Leblanc alkali waste at small
cost. Reduction of distillation to about one fourth, and corresponding saving of
loss in ammonia and steam, besides production of pearl hardening. By utilising
the lime in Leblanc alkali waste and the sulphuric acid of the salt cake, a saleable
article is obtained. Less loss of ammonia takes place. The loss of ammonia in
the waste liquor from the still is always a serious iteni.
Utilisation of the chlorine of the salt.
This will be evolved as hydrochloric acid in the ordinary manufacture of salt
cake, instead of being lost in the waste liquor from the still (together with an
equivalent quantity of lime) as calcium chloride in ordinary ammonia soda
processes.
No loss of sodium, (except in washings).
In processes at present in operation, this amounts to 33 per cent. of the total salt
used, and is lost in the waste liquor from the still. In this method, the excess of
salt cake used goes into the process again.

page_text: One form of plant which we have designed is as follows:-
On one side of a nearly square plot are the Solvay towers; on two opposite sides
of the same square plot are the bicarbonate filters and waste vessels. The first of
these are fed by the run off pipes from the Solvay towers.
Into the second of
these, the sulphuretted hydrogen pipes pass. On the fourth side of the square is a
mixing tank and at each end of it the tanks or settlers for the bicarbonate filter
liquor and the calcium sulph-hydrate respectively. Alongside the mixing tank, in
the square, are the pearl hardening filters. Beyond these, in line, a tank holding
the strong liquors from the pearl hardening filters, another tank holding the weak
washings from said filters, and a still. Beyond these, is a cooler for the vapours
from the still, and, on the same line with this, is a saturator. The cooler is
connected by pipes to the absorber, and the absorber and the tank containing the
strong liquor from the pearl hardening filter are connected with the saturator.
Near and connected with this saturator is a settler from whence the liquor is
withdrawn to be fed into the Solvay towers. Near this, a scrubber is situated,
taking the sulphuretted hydrogen from the absorber and passing it by means of a
pipe to the gas-holder which latter also receives the spare gas from the carbonators.
Dated this 18th day of July 1890.
WM. P. THOMPSON & Co.,
Patent Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Alkaline Carbonates and
Bye-products, and in Arrangement of Plant therefor.
We ARTHUR GEOFFREY HADDOCK of Church Road, Halewood, in the County
of Lancaster, Fellow of the Institute of Chemistry, and JOHN LEITH of Knowsley
Road, St. Helens, in the same County, Manufacturing Chemist, 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 has for its principal object a process of manufacturing alkali,
embracing, to a considerable extent, the advantages of the ammonia-soda process
and the Leblanc process, the hydrochloric acid being largely saved, and useful
bye-products, such as pearl hardening and sulphuretted hydrogen, are obtained,
while, by a variation of our process, Leblanc alkali waste is profitably utilised.
The process can be carried out either with or, as we prefer it, without the use
of ammonia.
In carrying out our invention, we form salt cake
ordinary manner, thereby obtaining hydrochloric acid.
of calcium in any of the following modes:-
:-
(sulphate of soda) in the
We also form sulphydrate
(1) Sulphuretted hydrogen, a bye-product in the present process as hereinafter
set forth, is passed into milk of lime or mixture containing lime, in closed vessels,
arranged in series. The sulphuretted hydrogen is absorbed and the calcium
rendered soluble as sulphydrate, the inert gases passing off through any convenient
purifier into the air.
(2) In place of milk of lime, Leblanc alkali waste mixed with water or other
earthy sulphide, such as sulphide of strontium or of barium, is used. The earthy
sulphide is formed by calcining the sulphate with fine coke, breeze or slack in a
closed furnace in the manner well known; oxidised Leblanc alkali waste can be
used in the same manner for this purpose.
To a solution of sulphydrate of calcium, formed in any of these ways or in any
other convenient manner, a neutral solution of salt cake (sulphate of soda) is added,
the two solutions being preferably as strong as possible. The result is that calcium
sulphate is precipitated nearly pure and as a fine powder, admirably fitted for any
of the purposes to which pearl hardening is applied.

page_text: The sodium bicarbonate for the most part (three fourths or more of the whole)
separates out in the solid form and is run on to filters, got as free as possible from
mother liquor (say by a vacuum filter or centrifugal machine) and dried for sale
or finished in a closed furnace to soda ash. Carbonic acid gas will be evolved from
the furnace in the finishing process, and can be passed into a receiver or be pumped
again into the carbonators.
The mother liquor from the bicarbonate of soda is concentrated by heat, either
to dryness or to form soda crystals, or until it contains about 14.5 per cent. Na,O
(alkali), when it is placed in the carbonators, and saturated with carbonic acid gas
as if it were an original solution. Three fourths or more of the remaining alkali
will separate as solid bicarbonate, and the remaining mother liquor, containing
alkali and any excess of sodium sulphate and sodium chloride (from the salt cake)
and a little sulphide of sodium, may be used for dissolving a further quantity of salt
cake, for making sodium sulphydrate. Its alkalinity will be serviceable in
neutralising the acidity of the salt cake and in precipitating the iron, lime and
magnesia contained in it.
A small quantity will also be used as aforesaid for removing calcium sulphate
dissolved in the sodium sulphydrate solution.
Sulphuretted hydrogen will be evolved from the carbonators during that operation
(see reaction). Part of this will require to be passed through the series of closed
vessels as before mentioned containing lime or compound earthy sulphides, to
make calcium or other sulphydrates, and, where a sulphide has been used to make
sulphydrate, the remainder (about one half of the whole) passed on to a gas-
holder for subsequent treatment to recover or utilise the sulphur or for other
purposes.
We hope to secure the following advantages by this process, few of which are
common to any other alkali process at present in operation
:-
The recovery of sulphur from Leblanc alkali waste and other earthy sulphides at
small cost.
By utilising the lime in Leblanc alkali waste and the sulphuric acid of the salt.
cake, a saleable article, hydrated calcium sulphate, is obtained.

page_text: Utilisation of the chlorine contained in the salt.
This will be evolved as hydrochloric acid in the ordinary manufacture of salt cake.
No loss of sodium (except that incidental to manipulation).
In processes at present in operation, this amounts to 33 per cent. of the total salt
used. In this method, any excess of salt cake used goes into the process again.
One form of plant which we have designed is as follows:-
A A are vessels containing milk of alkali waste or of other earthy sulphide or of
lime. They are supplied with sulphuretted hydrogen from the carbonators by
pipe B and deliver their sulphydrate of calcium by pipe C to settling tanks D D,
the liquid overflowing from the one tank into the other so as to assist in the settling.
From the last settler D, the liquor is carried to the mixer E by pipe F. G is a
tank for dissolving the sulphate of sodium in water, preferably mother liquor used
in washing.
The liquor is brought by pipe H to settling tanks I I, the liquor running from
the one to the other, as in the case of the sulphydrate settlers. From I, the clear
sulphate of soda liquor is brought by pipe J to mixer E, from the bottom
of mixer E, the material is run out into the pearl hardening filters K K by
means of pipe L. From K, the clear liquor is drawn into the vacuum pans M M
by means of pipe N. From N it passes to the vessel O, which is fitted with an
agitator, and, into this vessel, some of the mother liquor from the bicarbonate of
soda is brought so as to precipitate any remaining sulphate, the material is passed
to filter P and the liquor drawn from thence by means of the vacuum pans Q.
From these, by means of pipe R, it is pumped or injected by any convenient pump to
the carbonators S S. To these vessels, carbonic acid is brought by means of the
pipe T, and the sulphuretted hydrogen is drawn off to any desired point by means of
the pipe U, except that portion which is drawn off by pipe B to the sulphydrate
vessels A. W is a pipe withdrawing the bicarbonate to the filters XX, from which
the liquor is drawn by means of pipe Y and vacuum pans Z. This liquor can be
concentrated and passed again into the carbonators or used in the manner specified.
We have only mentioned soda, but, to a great degree, the process is also applicable
to the manufacture of carbonate of potash. There is, however, such a limited make
of potash, and bicarbonate of potash is so much more soluble than the soda salt that
we consider it unnecessary to refer more particularly to it.
In the foregoing, we have given the best mode known to us of carrying our
invention into effect.
We have, however, since filing our Provisional Application, made a few improve-
ments, which we have provisionally protected, and which consist in depriving the
lime kiln gas of uncombined oxygen, by heating it with hydrogen or hydrocarbons,
or a mixture of these, and a method of depriving the pearl hardening and refuse
waste of their residual sulphuretted hydrogen by passing the carbonic acid through
them on its way to the carbonators. Also we have proposed to utilise sulphate of
lime by calcining it with slack or other reducing agent in place of alkali waste ;
these points, however, we reserve to claim under our fresh application as above
mentioned.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that we are
aware that it has been proposed to treat sulphides of sodium and potassium with
carbonic acid gas for the formation of sulphuretted hydrogen, and that, during this
operation, alkaline sulphydrates and carbonates are formed, but our process differs
from this, in that we avoid the use of alkaline sulphides and furnacing operations
altogether, and thus eliminate a serious difficulty and expense, but that what we
claim is :-
:-
1. The improvement in the manufacture of alkaline carbonates and bye-products,
consisting in the cycle of operations hereinbefore described, by which bicarbonate of
soda and pearl hardening, precipitated sulphate of lime or fixed white sulphate of
barium or sulphate of strontium are obtained, substantially as above described.

page_text: 2. In the manufacture of bicarbonate of soda, the combined use of sulphydrate
of calcium or of other alkaline earth and sulphate of soda together with carbonic
acid, substantially as described.
3. The use of alkaline sulphydrates in combination with carbonic acid for the
manufacture of alkaline carbonates, substantially in the manner described and
subject to the disclaiming clause.
4. The general arrangement of plant for the manufacture of alkali, substantially
as and for the purposes herein set forth.
Dated this 18th day of April 1891.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.