IMPROVEMENTS IN THE MANUFACTURE OR PRODUCTION OF CARBONATE OF STRONTIUM ALSO PRODUCING CARBONATE OF POTASSIUM
Year: 1883

page_text: LETTERS PATENT to William Lloyd Wise of 46 Lincoln's Inn Fields, in
the County of Middlesex for an Invention of IMPROVEMENTS IN THE
MANUFACTURE OR PRODUCTION OF CARBONATE OF STRONTIUM ALSO PRODUCING
CARBONATE OF POTASSIUM a communication from Dr Hubert Grouven a
person resident at Leipzig Kingdom of Saxony, German Empire
PROVISIONAL SPECIFICATION left by the said William Lloyd Wise at the
Office of the Commissioners of Patents on the 31st March 1883.
OF
WILLIAM LLOYD WISE of 46 Lincoln's Inn Fields in the County of Middlesex
"IMPROVEMENTS IN THE MANUFACTURE OR PRODUCTION OF CARBONATE
STRONTIUM ALSO PRODUCING CARBONATE OF POTASSIUM (a communication from
Dr Hubert Grouven a person resident at Leipzig, Kingdom of Saxony, German
Empire)
As is well known coelestin or sulphate of strontium mixed with carbon requires
a white heat to reduce it perfectly to sulphide of strontium and by this intense
heat the crucible is destroyed the first time it is used. Moreover sulphide of
strontium by itself is very imperfectly decomposed by carbonic acid. Hence hereto-
fore sulphide of strontium or the cheaper sulphate in the form of cœlestin has not
been successfully employed in the manufacture of strontia on a commercial scale
Now according to this invention to obviate the above mentioned difficulties and
to render commercially practicable the use of coelestin the manufacture of carbonate
of strontium sulphide of potassium is employed in the process as hereinafter
described.
Sulphide of potassium at a red heat is far superior in its reducing power
to carbon by itself and will when mixed with carbon completely reduce coelestin
to sulphide of strontium at a comparatively low temperature. My foreign
correspondent has ascertained that sulphide of strontium will dissolve in boiling
water containing sulphide of potassium more readily than the sulphide of strontium
will dissolve by itself. He has furthermore ascertained, that the decomposition of
a hot solution of sulphide of strontium and sulphide of potassium by passing into

page_text: it carbonic acid gas is more rapid and complete than when the two solutions are
treated separately.
The sulphide of potassium is produced by mixing powdered coelestin with finely
powdered crystallised double salt of sulphate of potassium and magnesium.
When heated with carbon, this double salt is first reduced at a comparatively low
temperature into oxide of magnesium and sulphide of potassium. The latter which
is easily fusible attacks the adjacent molecules of coelestin
The following proportions for the mixture have been found advantageous:-
190 to 200 kilogrammes of coelestin in powder, equal to two atoms of sulphate of
strontium.
202 to 205 kilogrammes of the crystallised double salt of potassium and magnesium
equal to one atom of sulphate of potassium and magnesium.
150 kilogrammes of powdered coal (gas coal)
10 to 15 kilogrammes of the residue of sulphate of potassium from the preceding
process.
These materials must be finely powdered and very intimately mixed and stamped
together and then subjected to a red heat with complete exclusion of air.
The firing is by preference effected in cast iron cylindrical crucibles of about 110
millimetres internal diameter and 800 millimetres high. These crucibles are
suspended in the cover of a crucible furnace, heated by the burning gases and
superheated air. .
After each heating which lasts about 2 hours and a half one set of heated
crucibles is removed through the cover of the furnace and replaced by another set
freshly charged. A crucible of the above dimensions contains eight litres and will
hold so much of the above standard mixture as will contain 5 kilogrammes of
coelestin. In the upper part of each crucible (at the side) but below the cover of
the furnace several holes are provided, each 10mm in diameter through which the
carbonic oxide gas and sulphuretted hydrogen gas, produced in abundance during
the heating will escape and will burn in the oven, thereby adding to its heat. The
crucible is closed during heating with a cover which can be made air-tight with
clay in the ordinary manner.
This very important desulphuration of the contents of the crucibles, shown by
the above mentioned very large production of sulphuretted hydrogen gas depends
upon the presence of the 6 to 7 kilogrammes of. hydrogen contained in the powdered
coal which is steadily and slowly evolved during tlie heating.
The temperature in the oven should not be above the melting point of copper.
At such a heat the crucibles will stand well especially if made of the best Scottish
iron and will be but slowly destroyed. The inside of them is not corroded by the
above named mixture for during the heating it does not become fluid, but cakes
together into a lump, which on turning over the crucible falls out in a crisp flesh
coloured mass.
"
will
This mass, which for shortness sake will be called "sulphide mass
generally if properly heated weigh about 250 kilogrammes, it must dissolve
completely in dilute hydrochloric acid and must contain neither sulphuric acid nor
any undecomposed cœlestin
"
This "sulphide massi consisting of magnesia, hydrated oxide of strontium,
sulphate of strontium and sulphate of potassium is turned directly from the cooled
crucibles into the extraction vessels, whereby any contact with air is prevented. .
These vessels preferably round are provided with a lid and an agitator and steam
coil for boiling up the mass.
The lixiviation is carried on by decantation of the boiling liquid and repeated
additions of fresh water until the filtred liquid shows only traces of oxide of
strontium.
Seven of such vessels can be combined to form one set so as to obtain continuous
lixiviation and always concentrated filtrates
This liquid is clear, nearly colorless and if cooled down, more than one half of
the strontium will senarate out in large crystals as hydrate of strontia.

page_text: But this oxide contains a small quantity of sulphide of strontium therefor it is
not advisable to recover the oxide separately, but to convert the whole of it into
carbonate of strontium.
This conversion of the solution of strontium and sulphide of potassium into
carbonate of strontium and carbonate of potassium is effected by passing into the
boiling solution carbonic acid gas.
A heavy sediment of carbonate of strontia and a ten per cent solution of
carbonate of potash will be thereby obtained. The evolution of sulphuretted
hydrogen gas which is very great at the commencement of this operation will
decrease considerably after the carbonic acid has been passed through the solution
for several hours. The passing of the carbonic acid may be stopped as soon as a
strip of paper moistened with a solution of Acetate of Lead does not show any trace
of sulphuretted hydrogen in the evolved gas.
The carbonic acid must be free from oxygen gas or smoke and perfectly pure
carbonic acid is to be preferred, obtained by acting on limestone with superheated
steam The precipitated carbonate of strontium is separated from the potash
solution by a filter press, and may easily be lixiviated so as to be obtained as a
white cake containing 99% of carbonate of strontium and only a trace of sulphide
of iron.
The potash solution is evaporated, roasted and resolved in a minimum quantity
of cold water, whereby small quantities of oxide of iron and sulphate of potassium
are eliminated. A potash of 98% is obtained if the double sulphate of potassium
and magnesium employed has been nearly free from chlorides.
The small quantity of sulphate of potassium thus recovered is added to the
mixture for the next operation.
According to the above described process 100 kilogrammes of coelestin yield
about 66 kilogrammes of carbonate of strontium, and 28 kilogrammes of carbonate
of potassium The latter will cover about two thirds of the entire cost of
manufacture and therefore the manufacture of carbonate of strontium is a very
economical one.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Lloyd Wise in the Great Seal Patent Office on the 28th
September 1883.
OF
WILLIAM LLOYD WISE of 46 Lincolns Inn Fields in the County of Middlesex
IMPROVEMENTS IN THE MANUFACTURE OR PRODUCTION OF CARBONATE
STRONTIUM ALSO PRODUCING CARBONATE OF POTASSIUM (a communication from
D Hubert Grouven a person resident at Leipzig, Kingdom of Saxony, German
Empire)
As is well known coelestin or sulphate of strontium mixed with carbon requires
a white heat to reduce it perfectly to sulphide of strontium, and by this intense
heat the crucible is destroyed the first time it is used. Moreover sulphide of
strontium by itself is very imperfectly decomposed by carbonic acid. Hence
heretofore sulphide of strontium or the cheaper sulphate in the form of coelestin
has not been successfully employed in the manufacture of strontia on a commercial
scale.
Now according to this invention to obviate the above mentioned difficulties, and
to render commercially practicable the use of coelestin in the manufacture of
carbonate of strontium sulphide of potassium is employed in the process as
hereinafter described.
Sulphide of potassium at a red heat is far superior in its reducing power to
carbon by itself and will when mixed with carbon completely reduce coelestin to
sulphide of strontium at a comparatively low temperature. My foreign corre-
spondent has ascertained that sulphide of strontium will dissolve in hoiling water
containing sulphide of potassium more readily than the sulphide of strontium will
dissolve by itself. He has furthermore ascertained that the decomposition of a hot
solution of sulphide of strontium and sulphide of potassium by passing into it
carbonic acid gas is more rapid and complete than when the two solutions are
treated separately.
The sulphide of potassium is produced by mixing powdered coelestin with finely
powdered crystallised double salt of sulphate of potassium and magnesium.
When heated with carbon, this double salt is first reduced at a comparatively
low temperature into oxide of magnesium and sulphide of potassium. The latter
which is easily fusible attacks the adjacent molecules of coelestin.
The following proportions for the mixture have been found advantageous,
190 to 200 kilogrammes of coelestin in powder, equal to two atoms of sulphate of
strontium.
202 to 205 kilogrammes of the crystallised double salt of potassium and magnesium
equal to one atom of sulphate of potassium and magnesium.
150 kilogrammes of powdered coal (gas coal)
10 to 15 kilogrammes of the residue of sulphate of potassium from the preceding
process.
These materials must be finely powdered and very intimately mixed and stamped
together and then subjected to a red heat with complete exclusion of air.
The firing is by preference effected in cast iron cylindrical crucibles of about
110 millimetres internal diameter and 800 millimetres high. These crucibles are
suspended in the cover of a crucible furnace heated by the burning gases and
superheated air.
After each heating which lasts about two hours and a half one set of
heated crucibles is removed through the cover of the furnace and replaced by

page_text: another set freshly charged. A crucible of the above dimensions contains eight
litres and will hold so much of the above standard mixture as will contain
5 kilogrammes of coelestin. In the upper part of each crucible (at the side) but
below the cover of the furnace several holes are provided, each 10mm in diameter
through which the carbonic oxide gas and sulphuretted hydrogen gas, produced in
abundance during the heating will escape and will burn in the oven, thereby
adding to its heat. The crucible is closed during heating with a cover which can
be made air-tight with clay in the ordinary manner.
This very important desulphuration of the contents of the crucibles, shown by
the above mentioned very large production of sulphuretted hydrogen gas depends
upon the presence of the 6 to 7 kilogrammes of hydrogen contained in the
powdered coal which is steadily and slowly evolved during the heating.
The temperature in the oven should not be above the melting point of copper.
At such a heat the crucibles will stand well especially if made of the best Scottish
iron and will be but slowly destroyed. The inside of them is not corroded by the
above named mixture for during the heating it does not become fluid, but cakes
together into a lump, which on turning over the crucible falls out in a crisp flesh
coloured mass. This mass, which for shortness sake will be called "sulphide mass
will generally if properly heated weigh about 250 kilogrammes, it must dissolve
completely in dilute hydrochloric acid, and must contain neither sulphuric acid nor
any undecomposed coelestin.
"
"
This "sulphide mass consisting of. magnesia, hydrated oxide of strontium,
sulphate of strontium and sulphate of potassium is turned directly from the
cooled crucibles into the extraction vessels, whereby any contact with air is
prevented.
These vessels preferably round are provided with a lid and an agitator and
steam coil for boiling up the mass.
The lixiviation is carried on by decantation of the boiling liquid and repeated
additions of fresh water until the filtered liquid shows only traces of oxide of
strontium.
Seven of such vessels can be combined to form one set so as to obtain continuous
lixiviation and always concentrated filtrates.
This liquid is clear, nearly. colorless and if cooled down more than one half of
the strontium will separate out in large crystals as hydrate of strontia.
But this oxide contains a small quantity of sulphide of strontium, therefore it is
not advisable to recover the oxide separately, but to convert the whole of it into
carbonate of strontium.
This conversion of the solution of strontium and sulphide of potassium into
carbonate of strontium and carbonate of potassium is effected by passing into the
boiling solution carbonic acid gas.
A heavy sediment of carbonate of strontia and a ten per cent solution of
carbonate of potash will be thereby obtained. The evolution of sulphuretted
hydrogen gas which is very great at the commencement of this operation will
decrease considerably after the carbonic acid has been passed through the solution
for several hours. The passing of the carbonic acid may be stopped as soon as a
strip of paper moistened with a solution of acetate of lead does not show any trace
of sulphuretted bydrogen in the evolved gas.
The carbonic acid must be free from oxygen gas or smoke and perfectly pure
carbonic acid is to be preferred, obtained by acting on limestone with superheated
steam. The precipitated carbonate of strontium is separated from the potash
solution by a filter press, and may easily be lixiviated so as to be obtained as a
white cake containing 99% of carbonate of strontium and only a trace of sulphide
of iron.
°
The potash solution is evaporated, roasted and re-dissolved in a minimum
quantity of cold water, whereby small quantities of oxide of iron and sulphate of
potassium are eliminated.

page_text: A potash of 98% is obtained if the double sulphate of potassium and magnesium
employed has been nearly free from chlorides.
The small quantity of sulphate of potassium thus recovered is added to the
mixture for the next operation.
According to the above described process 100 kilogrammes of coelestin yield
about 66 kilogrammes of carbonate of strontium and 28 kilogrammes of carbonate
of potassium. The latter will cover about two thirds of the entire cost of
manufacture and therefore the manufacture of carbonate of strontium is a very
economical one.
Having described the nature of the said invention and the manner of carrying
it into practical effect as communicated to me as aforesaid I would have it
understood that what is considered to be novel and original and is therefore
claimed as the invention secured to me by the Letters Patent hereinabove in part
recited is ;
1. The combined manufacture of carbonate of strontium and carbonate of
potassium substantially in the manner herein before specified.
2. The conversion by heating in an appropriate crucible out of contact with
the air, of a mixture of sulphate of strontium, a double salt of sulphate of
potassium and magnesium, and coal, into a mass herein called "sulphide mass
substantially as specified
"
"
3. The lixiviation of the "sulphide mass out of, contact with the air sub-
stantially as and for the purpose specified.
4. The conversion of the dissolved strontium salts and sulphide of potassium
into carbonate of strontium and carbonate of potassium, by passing a stream of
carbonic acid gas through the boiling solution, substantially as specified..
5. The production of carbonate of strontium and carbonate of potassium from a
mixture of sulphate of strontium, sulphate of potassium and magnesium, and coal,
substantially as specified.
In witness whereof I the said William Lloyd Wise have hereunto set my
hand and seal this twenty second day of September in the year of our Lord one
thousand eight hundred and eighty three