IMPROVEMENTS IN THE MANUFAC- TURE OF HYDRATE OF STRONTIA AND HYDROSULPHIDE OF SODIUM
Year: 1883

page_text: LETTERS PATENT to Carl Friedrich Claus, of Mark Lane, in the City of
London, Chemist. for an Invention of "IMPROVEMENTS IN THE MANUFAC-
TURE OF HYDRATE OF STRONTIA AND HYDROSULPHIDE OF SODIUM
"
PROVISIONAL SPECIFICATION left by the said Carl Friedrich Claus at
the Office of the Commissioners of Patents on the 28th May 1883.
CARL FRIEDRICH CLAUS, of Mark Lane in the City of London, Chemist.
"IMPROVEMENTS IN THE MANUFACTURE OF HYDRATE OF STRONTIA AND HYDRO-
SULPHIDE OF SODIUM
"
My invention relates to the manufacture of hydrate of strontia and hydrosulphide
of sodium in the manner herein described that is to say.
I take a mixture of sulphate of strontia with carbonaceous matter and heat the
same to a high temperature whereby the sulphate of strontia is converted into
sulphide of strontium. I then dissolve the crude sulphide of strontium by boiling
the same with water. The clear solution thus obtained is run into tanks and
allowed to become cold.
If the hot solution is not too concentrated that is to say. if it does not greatly
exceed 25 or 30 degrees Twaddle, crystals will be formed, consisting principally of
hydrate of strontia. These crystals I collect, drain, and recrystallize and may sell
or otherwise dispose of them. The mother liquor which consists principally of a
solution of hydrosulphide (or sulphydrate) of strontium, I treat by the following
process, which is an essential feature of my present invention, I evaporate the
said mother-liquor to dryness and heat the dry residuum until one equivalent of
sulphur is expelled and only monosulphide of strontium remains. To this I add
carbonaceous matter (such as coal or coke dust) and I then heat the mixture to
bright redness or I add the carbonaceous matter to the mother liquor and run the
mixture on to the bed of a reverberatory furnace preferably in such a manner, that
at no time will there be a depth of more than about half an inch of liquor on the
bed of the furnace, or so that the liquid will be evaporated by the surface heat as
.

page_text: fast as it runs into the furnace leaving a dry mass, which I then heat as above
described to bright redness preferably in a separate reverberatory furnace.
After having been heated to a bright redness. I dissolve the mass by boiling it
with water. From the solution thus obtained a further quantity of hydrate of
strontia is crystallized out, which is collected and the mother liquor is treated as
herein-above described and I repeat the operation until all the strontia of the
original quantity of sulphate of strontia is converted into hydrate of strontia.
My invention also comprises the treatment of the mother liquor as follows, viz.
I add to the mother liquor a quantity of sulphate of soda equivalent, to the strontia
contained in the liquor and obtain a precipitate of sulphate of strontia, which I
separate from the liquid by filtration or decantation; I use such precipitate as
hereinabove described with reference to sulphate of strontia
The filtrate which consists of sulphhydrate (or hydrosulphide) of sodium, is
boiled down or concentrated. The concentrated solution is run into vessels and
allowed to crystallize, the crystals formed being a valuable article of commerce.
According to another part of my invention I decompose the hydrosulphide of
strontium solution or mother liquor by adding to it sulphate of magnesia and
heating the inixture until sulphide of hydrogen ceases to escape I then drain the
residuum which consists of sulphate of strontia and magnesia hydrate, add
carbonaceous matter, and heat the mixture in a furnace and otherwise treat
the same in the manner hereinabove described with reference to sulphate of
strontia.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Friedrich Claus in the Great Seal Patent Office on the
28th November 1883.
CARL FRIEDRICH CLAUS, of Mark Lane, in the City of London, Chemist,
"IMPROVEMENTS IN THE MANUFACTURE OF HYDRATE OF STRONTIA AND HYDRO-
SULPHIDE OF SODIUM
"3
This invention relates to the manufacture of hydrate of strontia and hydro-
sulphide of sodium, which I carry into practice in the manner herein-after described,
that is to say :-
I take a mixture of sulphate of strontia with carbonaceous matter and heat the
same to a high temperature, whereby the sulphate of strontia is converted into
sulphide of strontium I then dissolve the crude sulphide of strontium by boiling
the same with water. The clear solution thus obtained is run into tanks and
allowed to become cold. ·
If the hot solution is not too concentrated, that is to say, if it does not greatly
exceed 25 degrees Twaddle (or thereabout), crystals will be formed consisting
principally of hydrate of strontia.
These crystals I collect, drain and recrystallize, and I may sell or otherwise
dispose of them.
The mother-liquor consists principally of a solution of hydrosulphide (or sulph-
hydrate) of strontium, that is to say, in the said liquor one equivalent of strontium
is combined with two equivalents of sulphur. The treatment of this mother-
liquor forms the principal feature of my present invention.
I carry this part of my invention into practice, as follows, viz:-I evaporate
the said mother-liquor to dryness and heat the dry residuum (preferably in- the
presence of carbonaceous matter, such as coal or coke dust) until one equivalent
of sulphur is expelled and only monosulphide of strontium remains.
I however find it more advantageous to add the carbonaceous matter to the
mother-liquor and run the mixture on to the bed of a reverberatory furnace in such
a manner that at no time will there be a depth of more than about half an inch
of liquor on the bed of the furnace, and the liquid will therefore be evaporated by
the surface heat as fast as it flows into the furnace, leaving a dry mass, which I
then heat to redness preferably in a separate reverberatory furnace. The addition
of carbonaceous matter, in this instance, is not absolutely necessary, but it tends
to prevent the oxidation of the sulphide of strontium and to render the dry and
beated substance more porous and easier to dissolve.
After it has been heated to redness, I dissolve the mass by means of boiling
water. From the solution thus obtained a further quantity of hydrate of strontia
(nearly equal to one half of an equivalent of the strontia contained in the liquid)
is crystallized out and collected, and the mother-liquor, which consists of a
solution of hydrosulphide of strontium, is again treated in the manner just above
described.
I repeat this operation until practically all the strontia of the original quantity
of sulphate of strontia is converted into hydrate of strontia.
My invention also comprises the treatment of the mother-liquor as follows,
vis I add to the mother-liquor a quantity of sulphate of soda equivalent to the
strontia contained in the liquor and obtain a precipitate of sulphate of strontia,
which I separate from the liquid by filtration or decantation. I use such
precipitate as herein above described with reference to sulphate of strontia.
The filtrate, which consists of sulph-hydrate or hydrosulphide of sodium, is
boiled down or concentrated to the crystallizing point.

page_text: The concentrated solution is run into vessels and allowed to crystallize, the
crystals formed being an article of commerce.
To render these crystals free from iron, which would discolor them and unfit
them for some applications, I prefer to carry on the precipitation in brick tanks
and to effect the evaporation of the liquid by superheated steam. For the same
reason I also use only such sulphate of soda, in the above described process, as is
free from iron and other contaminating matter. When the presence of iron in the
crystals is of no consequence, iron pans may be used for boiling down the liquor
and impure and cheap sulphate of soda may be employed.
According to another part of my Invention I decompose the hydrosulphide of
strontium solution or mother-liquor by adding to it a quantity of sulphate of
magnesia equivalent to the strontia contained in the mother-liquor and by heating
the mixture until sulphide of hydrogen ceases to escape.
The sulphide of
hydrogen thus liberated is conveyed away and may be employed for various useful
purposes.
By the above described treatment a mixture (in equivalent quantities) of hydrate
of magnesia and sulphate of strontia is formed, which may then be further treated
by known methods to obtain useful commercial products therefrom; for instance,
it may be treated with fuel gases or carbonic acid whereby carbonate of strontia
and sulphate of magnesia will be formed. After separating these two substances
by filtration, the sulphate of magnesia may be again used for the purpose above
described.
Or the mixture of hydrate of magnesia with sulphate of strontia may be filtered
or drained from the liquid in which it is suspended and be mixed with carbon-
aceous matter. Such mixture may then be furnaced as described with reference to
sulphate of strontia alone, the furnaced product being lixiviated with boiling water
and crystallized as above described. The residuum from such lixiviation is hydrate
of magnesia, for which there are various useful applications.
Having thus fully described my said invention and the manner of performing
the same, I wish it understood that I claim, in the manufacture of hydrate of
strontia :-
First. The boiling down of sulph-hydrate of strontium solution to dryness and
heating (preferably in presence of carbonaceous matter) the residuum to convert
the same into monosulphide of strontium as above described.
Second. Decomposing the above named mother-liquor or solution of sulph-
hydrate of strontium by means of sulphate of soda, to form sulphate of strontin
and sulph-hydrate of sodium, as, and for the purpose, above described.
Third. Decomposing the above named mother-liquor or solution of sulph-
bydrate of strontium by means of sulphate of magnesia, as, and for the purpose,
specified.
In witness whereof I the said Carl Friedrich Claus have hereunto set my
hand and seal this Twenty eighth day of November in the year of Our Lord
One thousand eight hundred and eighty three.
CARL FRIEDRICH CLAUS (L.S.)