ImprovEMENTS IN UTILISING BYE PRODUCTS OF THE SODA AND POTASH MANUFACTURES
Year: 1871

page_text: LETTERS PATENT to James Mactear, of Glasgow, in the County of
Lanark, North Britain, Chemist, for the Invention of “ ImprovEMENTS
IN UTILISING BYE PRODUCTS OF THE SODA AND POTASH MANUFACTURES AND
Sealed the 13th February 1872, and dated the 8th September 1871.
PROVISIONAL SPECIFICATION left by the said James Mactear at the
Office of the Commissioners of Patents, with his Petition, on the
8th September 1871.
I, JAMES MACTEAR, of Glasgow, in the County of Lanark, North
Britain, Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN UTILISING BYE PRODUCTS OF THE SODA AND POTASH MANU-
FACTURES AND IN APPARATUS THEREFOR," to be as follows, that is to say :-
-
This Invention has for its object the economical and satisfactory
utilisation of the bye products known as yellow liquors arising in the
manufactures of soda and potash, and which are obtainable by collecting
the drainage of the waste heaps or by oxidising the so-called alkali waste

page_text: by any known means, and then lixiviating. These yellow liquors consist
chiefly of sulphides of calcium.
In carrying out this Invention according to one modification the
yellow liquor is mixed with lime, preferably in the state of finely divided
hydrate, and is then submitted to the action of sulphurous acid, any
known means being employed whereby gases and liquids can be made to
react on each other. The yellow liquor mixed with lime is by preference
placed in a vessel made of wood or other material, and agitated by means
of a stirrer, while sulphurous acid gas is forced or drawn through by
means of an aspirator; or a column or tower may be used, being fitted
with shelves, down over which the liquor is made to flow whilst the
sulphurous acid gas is passed upwards in the opposite direction. The
sulphurous acid is absorbed and a certain quantity of sulphur is pre-
cipitated. The tower can be fitted with doors or covers through which
the shelves can be scraped or cleaned from time to time as required.
The chief result of the decomposition is hyposulphite of lime, whilst
some sulphuretted hydrogen is also evolved, which last is to be dealt
with as herein-after described. The liquor now containing chiefly
hyposulphite of lime is mixed with fresh yellow liquor in such
proportion as will give a compound evolving the least possible amount
of sulphuretted hydrogen on the addition of hydrochloric acid. Known
tests are applied for determining the proportions with different liquors,
but as a guide it is preferred to have one equivalent of hyposulphite of
lime, Ca S, O₂, to each two equivalents of bi-sulphide of calcium, Ca S,
and one equivalent of hyposulphite of lime, Ca S, O₂, for each one
equivalent of sulphydrate of calcium, Ca'SHS; or liquor of the desired
composition may be obtained by limiting the action of the sulphurous
acid. The sulphuretted hydrogen evolved in the treatment of yellow
liquor by sulphurous acid may be utilised in various known
ways,
being preferred to pass it into or through liquor which has been
previously treated with sulphurous acid, so that it may be absorbed and
decomposed by any sulphurous acid present.
29
it
By another process the sulphuretted hydrogen is passed into or
through milk of lime, producing a sulphide or sulphides of calcium,
which with the lime, by preference somewhat in excess, is mixed with
fresh yellow liquor. and treated with sulphurous acid as herein-before
described. The liquor resulting from the herein-before described process.
or processes is to be decomposed with hydrochloric acid in suitable

page_text: vessels, preferably of wood, and fitted with agitators wrought by power,
and the resulting sulphur washed and dried or melted for use in any way
that may
be convenient.
By another modification the yellow liquor may also be treated with
sulphurous acid without the addition of lime, but in this case the
evolution of sulphuretted hydrogen is much greater, a result which is
to be avoided as much as possible from the risk of nuisance and loss.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Mactear in the Great Seal Patent Office
on the 6th March 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
MACTEAR, of Glasgow, in the County of Lanark, North Britain, Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of September, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said James Mactear, Her special licence
that I, the said James Mactear, my executors, administrators, and
assigns, or such others as I, the said James Mactear, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use,,exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN UTILISING BYE PRODUCTS OF THE SODA AND POTASH MANUFACTURES AND IN
APPARATUS THEREFOR," upon the condition (amongst others) that I, the
said James Mactear, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should
particularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said James Mactear, do hereby declarė
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement in writing, that is to say :-
My said Invention has for its object the economical and satisfactory
utilisation of the bye products known as yellow liquors arising in the
manufactures of soda and potash, and which are obtainable by collecting
the drainage of the waste heaps or by oxidising the so-called alkali waste
by any known means, and then lixiviating. These yellow liquors consist
chiefly of sulphides of calcium.
In carrying out my said Invention according to one modification the
yellow liquor is mixed with lime, preferably in the state of finely divided
hydrate, and is then submitted to the action of sulphurous acid, any
known means being employed whereby gases and liquids can be made to
react on each other. I prefer to place the yellow liquor mixed with lime
in a vessel made of wood or other material, and fitted with an agitator,
and whilst the mixture is being agitated to force the sulphurous acid gas
through it, or to draw the gas through by means of an aspirator; or a
column or tower may be used, being fitted with shelves, down over
which the liquor is made to flow whilst the sulphurous acid gas is passed
upwards in the opposite direction. The sulphurous acid is absorbed, and
a certain quantity of sulphur is precipitated. The tower should be fitted
with doors or covers through which the shelves can be scraped or cleaned
from time to time as required. The treatment with sulphurous acid
occasions a decomposition, the chief result of which is hyposulphite of
lime, whilst some sulphuretted hydrogen is also evolved, which last may
be dealt with as herein-after described. The liquor now containing
chiefly hyposulphite of lime is mixed with fresh yellow liquor in such
proportion as will yield a compound evolving the least practicable
amount of sulphuretted hydrogen on the addition of hydrochloric acid.
The proportions suitable for different liquors can be determined by
applying known tests, but I may mention that I prefer to have one
equivalent of hyposulphite of lime (Ca S, O₂) to each two equivalents of
bi-sulphide of calcium (Ca S₂), and one equivalent of hyposulphite of lime
(Ca S, O₂) for each equivalent of sulphydrate of calcium (Ca SHS); or
liquor of the desired composition may be obtained by limiting the action
of the sulphurous acid. Any sulphuretted hydrogen evolved in the

page_text: treatment of yellow liquor by sulphurous acid in the manner herein-
before described may be utilised in various known ways. I prefer to
pass it into or through liquor which has been previously treated with
sulphurous acid, so that it may be absorbed and decomposed by any
sulphurous acid present; or the sulphuretted hydrogen may be passed
into or through milk of lime, producing a sulphide or sulphides of
calcium, which with the lime, by preference somewhat in excess, is to
be mixed with fresh yellow liquor and treated with sulphurous acid as
herein-before described. The liquor resulting from the herein-before
described process or processes is to be decomposed by adding hydro-
chloric acid to it in suitable vessels, preferably of wood, and fitted with
agitators wrought by power. The sulphur is thereby precipitated,
leaving chloride of calcium in solution, and it may be washed and dried
or melted for use or for sale in any way that may be convenient.
By another modification, and one which I now prefer as it has in
practice proved to be the most convenient, the yellow liquor is treated
with sulphurous acid without the addition of lime. In carrying out this
modification of my improvements the sulphurous acid is used in solution
in water, the solution being prepared in any convenient known way, and
is run simultaneously with a stream of the yellow liquor into a decom-
posing vessel, which is preferably of wood, and is fitted with an agitator.
Hydrochloric acid is added to the yellow liquor and sulphurous acid,
being by preference run into the decomposing vessel along with the
other two streams. A temperature of about 145 degrees Fahrenheit
should be maintained in the decomposing vessel, and the three streams
should be proportioned to yield chloride of calcium and sulphur as the
final products of decomposition. The smell of the liquor in the decom-
posing vessel is a good working guide as to the proportions of sulphurous
acid and yellow liquor, whilst if a few drops of yellow liquor are
added to a sample from the mixture in the decomposing vessel a
dark coloration will take place if acid is wanting. When the process
is conducted in the manner described the evolution of sulphuretted
hydrogen is very slight. The sulphur is precipitated as in the modifi-
cation first herein-before described, and may be utilised in a similar way.
The residuary acid liquors from the manufacture of chlorine may be.
utilised as the source of the hydrochloric acid employed in the herein-
before described processes.
.

page_text: Having thus particularly described my said Invention, and the
manner of performing the same, I have to state that I do not restrict
myself to the precise details herein-before described, but that what I
believe to be novel and original, and claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,―
1. The utilising of the bye products of the soda and potash manu-
factures, and known as yellow liquors, by means of processes and
apparatus substantially such as are herein-before described.
2. The treating of the yellow liquor with sulphurous acid and hydro-
chloric acid in quantities proportioned to yield sulphur and chloride of
calcium, substantially as herein-before described.
In witness whereof, I, the said James Mactear, have hereunto set
my hand and seal, this Fifth day of March, in the year of our
Lord One thousand eight hundred and seventy-two.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
JAMES MACTEAR.. (L.S.)