IMPROVEMENTS IN THE PURIFICATION OF GAS AND THE UTILIZATION OF BYE-PRODUCTS BY THE MANUFACTURE OF SECONDARY PRODUCT THEREEROX
Year: 1877

page_text: LETTERS PATENT to Roger William Wallace, of the Chemical Works, New
Road, Battersea Park, in the County of Surrey, Manufacturing Chemist, and
Carl Friedrich Claus, of Groat St. Helen's, in the City of London, Consulting
Chemist, for the Invention of "IMPROVEMENTS IN THE PURIFICATION OF GAS
AND THE UTILIZATION OF BYE-PRODUCTS BY THE MANUFACTURE OF SECONDARY
PRODUCT THEREEROX
"
Sealed the 11th December 1877, and dated the 16th June 1877.
PROVISIONAL SPECIFICATION left by the said Roger William Wallace and
Carl Friedrich Claus at the Office of the Commissioners of Patents on the 16th
June 1877.
ROGER WILLIAM WALLACE, of the Chomical Works, New Road, Battersea Park,
in the County of Surrey, Manufacturing Chemist, and CARL FRIEDRICH CLAUS, of
"IMPROVEMENTS IN
Great St. Helen's, in the City of London, Consulting Chemist.
THE PURIFICATION OF GAS AND THE UTILIZATION OF BYE-PRODUCTS BY THE
MANUFACTURE OF SECONDARY PRODUCTS THEREFROM."
The object of part of our Invention for which we obtained Provisional Protection
on January 20th, 1877, and Numbered 272, was so to purify the gas from sulphide
and bisulphide of carbon as to obtain sulphocyanides as bye-products, and for that
purpose we proposed the use of solutions of sulphide of ammonium in combination
with solutions of sulphide of barium; but if we abstain from the production and
utilization of valuable bye-products, only hearing in mind the purification of the
gas itself from the above-named impurities, we employ solutions of sulphide of
barium only, by the action of which upon the bisulphides of carbon sulpho-car-
bonate of bariuin is formed, which may afterwards be converted in a separate
operation into sulpho-cyanide by treatment with sulphide of ammonium.
In another part of our process, described in the above-mentioned Provisional
Specification (namely, No. 272, A.D. 1877) referring to the purification of gas from
carbonic acid by means of gaseous and liquid ammonia, we proposed the use of a
number of towers or scrubbers, through which the ammoniacal liquors are pumped

page_text: in a systematic manner from one to another. By this means a certain fractionation
of the products of purification and condensation from the gas takes place in such a
manner that we obtain from the towers nearest the retorts almost pure carbonate
of ammonia, whilst from those of the opposite end liquid ammonia principally issues.
However in some of the intermediate towers the principal constituent is sulphide of
ammonium; this we propose to use from the scrubber which contains the liquor
richest in sulphide of ammonium, and we employ such sulphide of ammonium for
the purpose of purifying the gas from the bisulphide of carbon. As more sulphide
of ammonium is produced in this manner than is requisite for the above-named
purpose, we utilize the excess for the manufacture of sulphate of ammonia, and
employ the sulphide of hydrogen for the manufacture of sulphuric acid, for which
purpose it has been rendered sufficiently free from carbonic acid by the preceding
parts of our process.
Another manner in which we propose to manufacture sulphide of ammonium for
the purpose of purifying gas from sulphide of carbon is described in former Letters
Patent for the inanufacture of salts of barium and the like granted to us July 19,
1876, No. 2950), namely, by the double decomposition of the carbonate of aminonia
in gas liquor by sulphide of barium. We may however also produce it, though at
greater expense and less advantageously, by decomposing sulphate of ammonia by
sulphide of barium,
In districts where alkali waste is easily accessible we can produce sulphide of
ammonium also by means of it, instead of sulphide of barium, but the latter is much
more efficient, and produces a valuable bye-product.
We further propose the use of sulphide of ammonium by itself, prepared as above
described, as a purifying agent of gas from bisulphide of carbon.
Sulphide of sodium, though in a very much less degree, is also capable of
abstracting the bisulphide of carbon from the gas, but the practical difficulties
attached to its manufacture, as usually prescribed, have hitherto hindered it from
being practically applied for this purpose. The method we propose for its produc-
tion is the decomposition of sulphate of soda by means of sulphide of barium.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Roger William Wallace and Carl Friedrich Claus in the Great Seal
Patent Office on the 15th December 1877.
ROGER WILLIAM WALLACE, of the Chemical Works, New Road, Battersea Park;
in the County of Surrey, Manufacturing Chemist, and CARL FRIEDRICH CLAUS, of
Great St. Helen's, in the City of London, Consulting Chemist. "IMPROVEMENTS
IN THE PURIFICATION OF GAS AND THE UTILIZATION OF BYE-PRODUCTS BY THE
MANUFACTURE OF SECONDARY PRODUCTS THEREFROM."
The object of part of our Invention for which we obtained Letters Patent dated
January 20th, 1877, and Numbered 272, was so to purify the gas from sulphide and
bisulphide of carbon as to obtain sulpho-cyanides as bye-products, and for that
purpose we proposed the use of solutions of sulphide of ammonium in combination
with solutions of sulphide of barium; but if we abstain from the production and
utilization of valuable bye-products, only bearing in mind the purification of the
gas itself from the above-named impurities, we employ solutions of sulphide of
barium only, by the action of which upon the bisulphides of carbon sulpho-carbonate
of barium is formed, which may afterwards be converted in a separate operation
into sulpho-cyanide by treatment with sulphide of ammonium.
In another part of our process, described in the Specification of the above-named
Letters Patent referring to the purification of gas from carbonic acid by means of
gaseous and liquid ammonia, we treat principally of the absorption of carbonic acid
from the coal gas, but in the present Invention our object is to absorb the sulphide
of hydrogen also as far as the ammonia in the gas is capable of effecting this
object.
We stated in the said former Specification that the chloride of ammonium men-
tioned was decomposed by lime, and the ammonia produced was re-introduced into
the coal gas.
According to our present Invention, by the repeated decomposition of the chloride
of ammonium by means of lime, more ammonia is liberated than is necessary to
bind the carbonic acid in the gas alone, and as the whole of such ammonia is being
constantly introduced and re-introduced into the coal gas the surplus goes to take
up the sulphide of hydrogen existing as impurity in the coal gas, forming sulphide
of ammonium, so that the quantity of ammonia liquor or gas liquor which is now
being sent out from gas works for the manufacture of commercial salts of ammonia
will still be the same, but its composition will be different, that is to say, its chief
constituents will be sulphide of ammonium. As the supply of ammonia from coal
gas is sufficient to bind four-fifths of the sulphide of hydrogen in the coal gas, about
one-fifth only of this impurity would thus have to be dealt with in other ways.
This sulphide of ammonium we propose to use from the scrubber which contains
the liquor richest in the same, and we employ such sulphide of ammonium for the
purpose of purifying the coal gas from the bisulphide of carbon by passing the coal
gas through the same. For the purposes of this purification the ammoniacal gas
passes along with the coal gas in the direction from the retorts towards the gas
holder. In its passage through these towers the ammoniacal gas combines with the
impurities of the gas (carbonic acid and sulphide of hydrogen) forming carbonate of
ammonia and sulphide of ammonium, and as always a slight excess of ammonia is
admitted into the gas this also travels along with the other compounds named.
Down the last tower of the series water or weak liquors from previous operations' is
caused to trickle to arrest the last traces of ammoniacal compounds. The liquor
formed by their condensation is pumped to the top of the preceding tower in th
opposite direction to that in which the coal gas travels, and being made to trickle
down this tower condenses a portion of the ammoniacal compounds. Arrived at the
bottom it is pumped to the top of the tower preceding it, and so forth' until it
reaches the last tower in the series, that is to say, the one nearest the retorts.
During the passage of the liquor in the direction from the holder towards the
retorts the sulphide of ammonium condensed in it is decomposed again by the

page_text: carbonic acid so long as carbonic acid is present in the gas, sulphide of hydrogen
being driven forward with the gas in the direction towards the holder, whilst the
carbonate of ammonia (which is formed simultaneously) is conveyed in the liquor
towards the retorts. The liberated sulphide of hydrogen combines further on with
the ammonia, forming sulphide of ammonium. As we employ a number of towers,
and as the action described goes on with great regularity, a solution of salts of
ammonium will be found in one or two of the towers, consisting chiefly of sulphide
of ammonium. More sulphide of ammonium is produced in this manner than is
requisite for the above-named purpose, we therefore utilize the excess for the manu-
facture of sulphate of ammonia, and employ the sulphide of hydrogen liberated for
the manufacture of sulphuric acid, for which purpose it has been rendered sufficiently
free from carbonic acid by the preceding parts of our process.
Another manner in which we propose to manufacture sulphide of ammonium,
for the purpose of purifying gas from sulphide of carbon, is described in the Specifi-
cation of former Letters Patent for the manufacture of salts of barium and the like,
dated July 19th, 1876, No. 2950, namely, by the double decomposition of the car-
bonate of ammonia in gas liquor by sulphide of barium. We may however also
produce it, though at a greater expense and less advantageously, by decomposing
sulphate of ammonium by sulphide of barium.
In districts where alkali waste is easily accessible we can produce sulphide of
ammonium also by means of the same instead of sulphide of barium, but the latter
is much more efficient and produces a valuable bye-product.
We further propose the use of sulphide of ammonium by itself, prepared as above
described, as a purifying agent of gas from bisulphide of carbon.
Sulphide of sodium, though in a very much less degree, is also capable of
abstracting the bisulphide of carbon from the gas, but the practical difficulties
attached to its manufacture, as usually prescribed, have hitherto hindered it from
being practically applied for this purpose. The method we propose for its produc-
tion is the decomposition of sulphate of soda by means of sulphide of barium.
Having thus fully described our said Invention, and the manner of performing
the same, we wish it understood that we claim,-
First. In the purification of coal gas from bisulphide of carbon or sulphur com-
pounds other than sulphide of hydrogen the use of the solution of sulphide of
barium.
Second. The production of sulphide of ammonium by the action of gaseous or
liquid ammonia (obtained as described in the said former Specification) on the
impurities of the gas.
Third. In the purification of coal gas from bisulphide of carbon the application of
the solutions of sulphide of ammonium formed by the absorption of sulphide of
hydrogen by ammonia, as above described.
Fourth. The utilization of the surplus sulphide of ammonium not required for
the said purpose for the manufacture of ammoniacal salts of ammonia, as above
described.
Fifth. In the purification of coal gas from bisulphide of carbon the use of solutions
of sulphide of ammonium produced by means of sulphide of barium or alkali waste
and carbonate or sulphate of ammonium.
Sixth. In the purification of coal gas the use of solutions of sulphide of sodium
produced by solutions of sulphide of barium and sulphate of soda.
In witness whereof, I, the said Carl Friedrich Claus, for myself and on behalf
of the said Roger William Wallace, have hereunto set my hand and seal, this
Fifteenth day of December, in the year of our Lord One thousand eight
hundred and seventy-seven.
CARL FRIEDRICH CLAUS. (L.S.)