IMPROVEMENTS IN LINING FURNACES TO BE USED FOR THE MANUFACTURE OF SULPHIDE OF SODIUM AND SULPHIDE OF POTASSIUM
Year: 1876

page_text: LETTERS PATENT to Walter Weldon, of Abbey Lodge, Merton, in the County
of Surrey, for the Invention of "IMPROVEMENTS IN LINING FURNACES TO BE
USED FOR THE MANUFACTURE OF SULPHIDE OF SODIUM AND SULPHIDE OF
POTASSIUM."
Sealed the 21st December 1876, and dated the 28th August 1876.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the Office
of the Commissioners of Patents on the 28th August 1876.
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey. "IM-
PROVEMENTS IN LINING FURNACES TO BE USED FOR THE MANUFACTURE OF SULPHIDE
OF SODIUM AND SULPHIDE OF POTASSIUM"
"
It has been many times proposed, and, although less frequently, it has been
many times attempted, to manufacture soda by converting sulphate of soda into
sulphide of sodium, and then decomposing such sulphide of sodium by one or other
of certain known means. This method of manufacturing soda would permit the
recovery and re-utilization of the whole of the sulphur contained in the sulphate of
soda employed, and would avoid the production of the offensive residue known as
"alkali waste But all attempts to practically apply this method have hitherto
failed. A principal cause of this failure has been the very powerfully corrosive
action of sulphide of sodium upon the materials of which all furnaces or other
appliances for the manufacture of that body have hitherto been constructed. All
such furnaces or other appliances have been made either of brick or of cast iron,
and at the temperature necessary to be employed for the production of sulphide of
sodium by the reaction upon sulphate of soda, of coal, coke, or other carbon-
aceous matter, sulphide of sodium attacks both brick and cast iron with extremo
energy. Hence, when only enough carbonaceous matter to decompose the sulphate
of soda has been used the furnaces employed have become useless after a very few
operations, and the product obtained has been largely contaminated by compounds
resulting from the reaction of sulphide of sodium upon the materials of which the
furnaces have been formed
When an excess of carbonaceous matter has been employed the contact of the
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page_text: resulting sulphide of sodium with the material of the furnaces has been less
intimate, and the wear of the furnaces has consequently been less than in the other
case; but the wear of the furnaces has still been excessive, and although the
product has contained a smaller proportion of impurities due to corrosion of the
furnaces or other apparatus it has contained in addition a more or less considerable
residue of carbonaceous matter.
The furnaces or other apparatus in which it has hitherto been attempted to
manufacture sulphide of sodium have thus worn out too rapidly to permit the
manufacture to be continued, and the product obtained in such furnaces or other
apparatus has always been extremely impuie.
The object of the prosent Invention is to provide apparatus for the manufacture
of sulphide of sodium which shall not be liable to corrosion thereby, and which,
while thus avoiding what has hitherto rendered the first step in the process
referred to in the first paragraph of this Specification impracticably costly, shall at
the same time render possible and easy the production of a very much purer
sulphide of sodium than has ever hitherto been obtained.
I accomplish this object by lining with blocks of consolidated magnesia the
furnaces or other apparatus in which the sulphide of sodium is to be manufactured.
These magnesia blocks or bricks may be obtained by the method which has
occasionally been employed for the production of inagnesia crucibles, but I prefer
to obtain them by mixing powdered magnesia with a small quantity of gas tar,
submitting the mixture to very powerful pressure in suitable moulds, and then
heating the blocks or bricks so obtained in such manner and under such conditions
that the tar in them shall undergoe destructive distillation without the blocks or
bricks themselves losing their shape during this operation. Such other aggluti-
nating bodies as leave a residue of carbon when subjected to destructive distillation
may be used instead of tar, but tar will usually be most economical and convenient.
The magnesia blocks or bricks may be of any suitable size or shape, but I prefer
that they should be so shapen as to be capable of fitting one into another. And
in fitting them together in the furnace or other apparatus to be lined with them
I prefer to smear those surfaces of them which are to come into mutual contact
either with tar or with a mixture of tar and powdered magnesia
The use in the manufacture of sulphide of sodium of furnaces lined, as I have
above described, will enable sulphide of sodium to be produced not only much
more economically but of very much purer quality than heretofore. The sulphide
of sodium produced in such furnaces will indeed be practically a new product.
What has hitherto been produced under the name of sulphide of sodium has really
been a mixture of many bodies, requiring complicated treatment for its conversion
into merchantable soda, and indeed containing an appreciable proportion of com-
pounds not capable of conversion thereinto; but in such apparatus as I have
described it will be easy to produce almost chemically pure sulphide of sodium,
capable of conversion into merchantable soda by much simpler means than any
hitherto proposed.
The Invention, the nature of which is above set forth, is equally applicable to
the manufacture of sulphide of potassium.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Weldon in the Great Seal Patent Office on the 26th February
1877.
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey. "IM-
PROVEMENTS IN LINING FURNACES TO BE USED FOR THE MANUFACTURE OF SULPHIDE
OF SODIUM AND SULPHIDE OF POTASSIUM.",
Theobject of the present Invention is to enable sulphide of sodium and sulphide

page_text: of potassium to be manufactured without that rapid destruction of the furnaces or
other apparatus employed which has been experienced whenever the manufacture
of these sulphides has been attempted hitherto
I accomplish this object by lining the furnaces, crucibles, retorts, or other
apparatus in which sulphide of sodium or sulphide of potassium is to be manu-
factured, with blocks, bricks, or other masses of consolidated magnesia
I prefer to obtain the said blocks, bricks, or other masses of consolidated
magnesia, by mixing finely powdered magnesia with a small quantity of gas tar,
filling the resulting mixture into metal or other suitable moulds, submitting the
mixture therein to pressure applied, by means of a press or otherwise, to metal or
other blocks fitting suitably into the moulds, and then heating the blocks or bricks
so obtained until the whole of the tar in them has undergone destructive distilla-
tion, which will be known by their not giving off any further quantity of any
of the volatile products of the destructive distillation of tar, either on longor
heating or on heating to a higher temperature. This operation of heating the
blocks or bricks should be performed in a muffle furnace, the blocks or bricks either
remaining in the moulds in which they were formed or being otherwise so encased
and confined that they cannot materially lose their shape or change their dimen-
sions during that operation.
In forming blocks, bricks, or other masses of magnesia, as above described,
starch, flour paste, or almost any agglutinating body which leaves a residue of solid
carbon on being subjected to destructive distillation may be used instead of tar,
but tar will usually be most economical and convenient. I prefer that the blocks
or bricks should be so shapen as to be capable of dovetailing or otherwise fitting
into one another, but this is not essential And in fitting, them together in the
furnaces or other apparatus to be lined with them I prefer to coat those surfaces of
them which are to come into mutual contact with a thin film, either of tar or of
a mixture of tar with finely powdered magnesia.
Having thus fully described and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I claim as the Invention to be
secured to me by the herein-before in part recited Letters Patent,―
Firstly. Lining furnaces or other apparatus to be used for the manufacture of
sulphide of sodium or of sulphide of potassium with blocks, bricks, or other massos
of consolidated magnesia, however produced or obtained.
And, Secondly. Lining furnaces or other apparatus to be used in the manu-
facture of sulphide of sodium or of sulphide of potassium with blocks, bricks, or
other masses produced by mixing magnesia with gas tar or other suitable aggluti-
nating body, as above set forth, and then treating such mixture substantially as is
above described.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand
and seal, this Thirtieth day of January, in the year of our Lord One
thousand eight hundred and seventy-seven.