Improvements relating to the Treatment of the Spent Lyes Used in the Manufacture of Cellulose by Means of Sulphites, for the Recovery of Sulphurous Acid therefrom, and to the Utilization of the said Lyes after such Treatment.
Year: 1886

page_text: Date of Application, 18th Oct., 1886.
Complete Left, 15th July, 1887.
Complete Accepted, 16th Sept., 1887. -
RESERV
Improvements relating to the Treatment of the Spent Lyes Used
in the Manufacture of Cellulose by Means of Sulphites, for the
Recovery of Sulphurous Acid therefrom, and to the Utilization
of the said Lyes after such Treatment.
I ADOLPH FRANK of 80 Leibnitzstr, Charlottenberg, Prussia German Empire,
Doctor of Philosophy do hereby declare the nature of this invention to be as
follows:-
This invention relates to the recovery (in the form of calciummonosulphite) of the
sulphurous acid, contained in the spent lyes resulting in the manufacture of cellulose
by the sulphite process; to the treatment of the said calciummonosulphite to obtain
acid sulphite solutions; and to the utilization of the said lyes after the precipitation
of the sulphurous acid.
The lyes resulting from the manufacture of cellulose, paper pulp, textile fibres and
the like by the so-called sulphite process contain sulphurous acid some of which is
free, while some in the form of sulphites and bisulphites (according to the base of the
sulphurous acid solution used), is united with calcium, magnesium, sodium or
potassium. The recovery of this sulphurous acid can be effected only partially by
boiling, because part of the said bisulphites, as I have determined, are in the spent
lyes in combination with organic substances, which in boiling, even when acids are
added, decompose only slowly.
Moreover, the monosulphite of calcium deposited in the boiling of the free
sulphurous acid from spent lyes, is so muddy and so contaminated by organic substance
that it can with difficulty be obtained and used again.
A quantity of sulphurous acid and its compounds contained in the spent lyes is,
however, very deleterious, inasmuch as, on the one hand, when they are let into
water-courses, the water is contaminated by the abstraction of oxygen and the
formation of sulphuric acid; and, on the other hand, the further use of the available
organic ingredients of the lye is rendered difficult.

page_text: The present invention has for its object the removal and recovery of the sulphites
from the spent lyes, so that eventually the solution freed from the said sulphites can
be utilized for forage and for manuring purposes.
To separate the sulphurous acid I add to the liquid let out of the boilers :-
A) in case it contains lime as a base, a quantity of caustie lime or carbonate of
lime, equivalent to its proportion of sulphurous acid (deducting a quantity equivalent
to that already combined with the lime in the form of monosulphite).
B) in case it contains magnesia as a base a quantity of lime, equivalent to the entire
proportion of sulphurous-acid.
a
C) in case the boiling-lye contains neutral or, acid sulphite of soda or potash,
mixture of calcium chloride and lime, which is such that it contains a quantity of
calcium chloride, equivalent to the soda contained in the solution, whilst for the other
sulphurous acid is given the equivalent quantity of lime as caustic lime or carbonate
of lime.
Almost all the sulphurous acid contained in the boiling lyes is, thereby in every
case precipitated as calciummonosulphite which dissolves with difficulty, the organic
compounds of the bisulphites and of the soluble acid sulphites themselves being
decomposed. The precipitation can be promoted by adding an excess of lime, and
also by heating and stirring.
The precipitated calciummonosulphite can be separated from the lye through the
medium of filters or filter presses, and is cleaned from the organic substances which
still adhere to it, or have become insoluble in the liquid which is no longer acid, by
elutriation with water, to which can be added neutral salts (common salt, calcium
chloride, Glauber's salt) for the purpose of increasing the specific weight. The
calciummonosulphite, owing to its greater specific weight, thereby separates from
the lighter organic substances and eventually also from magnesia precipitated with
the same.
The cleansing can however also be effected by washing the precipitate of mono-
sulphite with a highly diluted solution of sulphurous acid or with a solution of acid
sulphite of lime or any other acid sulphite of an alkali, magnesia or an alkaline earth.
The organic substances precipitated with it and adhering thereto are thus again
dissolved and the calciummonosulphite is obtained clean.
I use the calciummonosulphite cleansed by elutriation or washing in various manners
for producing fresh acid solutions of sulphite.
I) by adding to the same, after it has been stirred up with water, sulphurous
acid or
II) by introducing the sulphite into a mixture of water and sulphuric acid, in
which the quantity of the sulphuric acid is such that it unites with only a portion
of the oxide of calcium contained in the monosulphate to form sulphate of calcium,
whilst the sulphurous acid which has thereby become free changes the undecomposed
monosulphite into a solution of acid sulphite of lime of the exact composition desired.
As a valuable bye-product which can be used directly in the manufacture of paper,
precipitated sulphate of lime-gypsum (annalin or pearl hardening or pearl-white)
is obtained.
In the II method I replace any loss of sulphurous acid which has occurred during
the boiling process &c. by adding to the monosulphite obtained by precipitation from
the lyes, such neutral sulphite of lime as obtained by other chemical processes.
If from the solution of acid sulphite of lime obtained according to methods I or II
a solution of acid sulphite of magnesia, or of acid sulphite of soda is to be prepared
the lime is precipitated as calcium sulphate, which can likewise be used as gypsum
(Annalin or pearl-white) by adding a suitable quantity of magnesium sulphate or
sodium sulphate.
III. The calciummonosulphite can be treated directly to form acid sulphite of soda,
by introducing the sulphite into a solution of acid sulphate of soda. In this case
neutral sulphate of lime precipitates, which precipitate can also be used as gypsum
(Annalin or pearl-white) and a solution of acid sulphite of soda is obtained. This
solution can then again be converted into a solution of acid sulphite of magnesia or

page_text: of acid sulphite of lime by mixing it with a quantity of sulphate of magnesia, chloride
of magnesium or chloride of calcium respectively, equivalent to the proportion of soda
contained therein.
The precipitation of the calciummonosulphite from the cellulose-lyes is however
effected more easily by caustic lime than by carbonate of lime, but when using caustic
lime the alkaline reaction of the lyes, caused by an excess of the same, is injurious for
many purposes, especially for the otherwise advantageous utilization of the lyes freed
from sulphites as forage and as manure, for which they are very well adapted, because
they contain, besides large quantities of carbon hydrates, and nitrogenous bodies, also
many of the ingredients found in the plants treated, alkalies, phosphoric acid, silica
acid, and the like in a dissolved state. According to chemical analyses these lyes
show in their composition a certain resemblance to the phlegms of the beet-root-
molasses distilleries but have the advantage of containing more sugar and a smaller
proportion of salt.
For the removal of the free caustic lime and for the oxidation of the sulphite of
lime still dissolved in small quantities, a mixture of carbonic acid and atmospheric air
is caused to pass through the solutions, should the use as forage or manure be
intended.
The same treatment is also necessary if the lye is to be let into water courses without
injuring the water. If the use as manure is intended, a quantity of acid phosphate of
lime, sufficient for forming a basic phosphate for the precipitation of the caustic lime
is added.
The neutralization of the caustic lime when the lye is utilized as manure can also
be effected by soluble magnesia salts or kainite, at the same time the manuring effect
is correspondingly increased. By adding alkaline carbonates nearly all the lime still
contained in the solution either free or combined can be precipitated, but after this
operation, so far as the use of the lye as forage is concerned, a neutralization of the
alkali with hydrochloric acid must be effected. The liquid can then be concentrated
by evaporation and thus reduced in weight and rendered easy of transport.
HASELTINE, LAKE & CO.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: Improvements relating to the Treatment of the Spent Lyes Used
in the Manufacture of Cellulose by Means of Sulphites, for the
Recovery of Sulphurous Acid therefrom, and to the Utilization
of the said Lyes after such Treatment.
I, ADOLPH FRANK, of 80 Leibnitzstr, Charlottenburg, Prussia, German Empire,
Doctor of Philosophy do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
This invention relates to the recovery (in the form of calcium monosulphite) of the
sulphurous acid, contained in the spent lyes resulting in the manufacture of cellulose
by the sulphite process; to the treatment of the said calcium monosulphite to obtain
acid sulphite solutions; and to the utilization of the said lyes after the precipitation of
the sulphurous acid.
The lyes resulting from the manufacture of cellulose, paper pulp, textile fibres and
the like by the so-called sulphite process contain sulphurous acid some of which is
free, while some in the form of sulphites and bisulphites (according to the base of the
sulphurous acid solution used) is united with calcium, magnesium, sodium or
potassium. The recovery of this sulphurous acid can be effected only partially by
boiling, because part of the said bisulphites, as I have determined, are in the spent
lyes in combination with organic substances, which in boiling, even when acids are
added, decompose only slowly.
Moreover, the monosulphite of calcium deposited in the boiling of the free sulphurous
acid from spent lyes, is so muddy and so contaminated by organic substance that it
can with difficulty be obtained and used again.
A quantity of sulphurous acid and its compounds contained in the spent lyes is,
however, very deleterious, inasmuch, as on the one hand, when they are let into water-
courses, the water is contaminated by the abstraction of oxygen and the formation of
sulphuric acid; and on the other hand, the further use of the available organic
ingredients of the lye is rendered difficult.
The present invention has for its object the removal and recovery of the sulphites
from the spent lyes, so that eventually the solution freed from the said sulphites can
be utilized for forage and for manuring purposes.
To separate the sulphurous acid I add to the liquid let out of the boilers.
A) In case it contains lime as a base, a quantity of caustic lime or carbonate of
lime, equivalent to its proportion of sulphurous acid (deducting a quantity equivalent
to that already combined with the lime in the form of monosulphite).
B) In case it contains magnesia as a base, a quantity of lime, equivalent to the
entire proportion of sulphurous acid.
a
C) In case the boiling lye contains neutral or acid sulphite of soda or potash,
mixture of calcium chloride and lime, which is such that it contains a quantity of

page_text: calcium chloride, equivalent to the soda contained in the solution whilst for the other
sulphurous acid is given the equivalent quantity of lime as caustic lime or carbonate
of lime.
Almost all the sulphurous acid contained in the boiling lyes is thereby in every
case precipitated as calciummonosulphite which dissolves with difficulty, the organic
compounds of the bisulphites and of the soluble acid sulphites themselves being
decomposed. The quantity of calcium monosulphite can still be increased by .
introducing into this liquid containing lime in excess the vapours and gases passing
from the boilers and carrying with them sulphurous acid, whereby this sulphurous
as calcium
acid escaping from the boilers is passed with the lime in excess
monosulphite into the precipitate and cannot be lost. The precipitation can be
promoted by adding an excess of lime, and also by heating and stirring.
The precipitated calcium monosulphite can be separated from the lye through the
medium of filters or filter presses and is cleaned from the organic substances
which still adhere to it, or have become insoluble in the liquid which is no longer
acid, by elutriation with water, to which can be added neutral salts (common salt,
calcium chloride, Glauber's salt) for the purpose of increasing the specific weight.
The calcium monosulphite, owing to its greater specific weight, thereby separates
from the lighter organic substances and eventually also from magnesia precipitated
with the same.
The cleansing can however also be effected by washing the precipitate of
monosulphite with a highly diluted solution of sulphurous acid or with a solution of
acid sulphite of lime or any other acid sulphite of an alkali, magnesia, or an alkaline
earth. The organic substances precipitated with it and adhering thereto are thus
again dissolved and the calcium monosulphite is obtained clean.
I use the calcium monosulphite cleansed by elutriation or washing in various ways
for producing fresh acid solutions of sulphite.
I). By adding to the same, after it has been stirred up with water, sulphurous
acid or
II). By introducing the sulphite into a mixture of water and sulphuric acid, in
which the quantity of the sulphuric acid is such that it unites with only a portion of
the oxide of calcium contained in the monosulphite to form sulphate of calcium,
whilst the sulphurous acid which has thereby become free changes the undecomposed
monosulphite into a solution of acid sulphite of lime of the exact composition desired.
As a valuable bye-product which can be used directly in the manufacture of paper,
precipitated sulphate of lime, gypsum (annalin or pearl hardening or pearl-white) is
obtained.
In the II method I replace any loss of sulphurous acid which has occurred during
the boiling process &c. by adding to the monosulphite obtained by precipitation from
the lyes, such neutral sulphite of lime as obtained by other chemical processes.
If from the solution of acid sulphite of lime obtained according to methods I or II
a solution of acid sulphite of magnesia, is to be prepared the lime is precipitated as
calcium sulphate which can likewise be used as gypsum (annalin or pearl-white) by
adding a suitable quantity of magnesium sulphate.
III. Calcium monosulphite can be treated directly to form acid sulphite of soda,
by introducing the sulphite into a solution of acid sulphate of soda. In this case
neutral sulphate of lime precipitates, which precipitate can also be used as gypsum
(annalin or pearl-white) and a solution of acid sulphite of soda is obtained. This
solution can then again be converted into a solution of acid sulphite of magnesia or
of acid sulphite of lime by mixing it with a quantity of sulphate of magnesia, chloride
of magnesium or chloride of calcium respectively equivalent to the proportion of soda
contained therein. The precipitation of the calcium monosulphite from the cellulose
lyes is effected more easily by caustic lime than by carbonate of lime, but when using
caustic lime the alkaline reaction of the lyes, caused by an excess of the same is
injurious for many purposes, especially for the otherwise advantageous utilization of
the lyes freed from sulphites as forage and as manure, for which they are very well
adapted because they contain besides large quantities of carbon hydrates and

page_text: nitrogenous bodies, also many of the ingredients found in the plants treated, alkalies,
phosphoric acid, silicic acid, and the like in a dissolved state. According to chemical
analyses these lyes show in their composition a certain resemblance to the phlegms of
the beet-root-molasses distilleries but have the advantage of containing more sugar
and a smaller proportion of salt.
For the removal of the free caustic lime and for the oxidation of the sulphite of
lime still dissolved in small quantities, a mixture of carbonic acid and atmospheric
air is caused to pass through the solutions, should the use as forage or manure be
intended.
The same treatment is also necessary if the lye is to be let into water courses
without injuring the water. If the use as manure is intended, a quantity of acid
phosphate of lime, sufficient for forming a basic phosphate for the precipitation of the
caustic lime is added.
The neutralization of the caustic lime when the lye is utilized as manure can also
be effected by soluble magnesia salts or kainite, at the same time the manuring effect
is correspondingly increased. By adding alkaline carbonates nearly all the lime still
contained in the solution either free or combined can be precipitated, but after this
operation, so far as the use of the lye as forage is concerned, a neutralization of the
alkali with hydrochloric acid must be effected. The liquid can then be concentrated
by evaporation and thus reduced in weight and rendered easy of transport.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is.
First. The process of precipitating by means of lime or proper calcium salts and in
the form of calcium monosulphite, the free and combined sulphurous acid which is
still contained in the spent lyes resulting from the manufacture of cellulose by means
of the sulphite process in combination with the said calcium monosulphite being
cleansed from adhering organic substances by elutriation or by washing with a
solution of sulphurous acid or of acid sulphites of the alkali or alkaline earths.
Second. The process of converting calcium monosulphite, by partial decomposition
with sulphuric acid into sulphite of lime, in which process calcium sulphate (annalin)
is obtained as a bye-product.
Third. The process of preparing from acid calcium sulphite solutions, by the
precipitation of the same with magnesium sulphate, acid solutions of magnesium
sulphite, at the same time obtaining calcium sulphate (annalin).
Fourth. The process of preparing acid sodium sulphite solutions by decomposing
the calcium monosulphite with acid sulphate of soda, calcium sulphate (annalin) being
precipitated as a bye product.
Fifth. The removal of the sulphurous acid and sulphites contained in the sulphite
lyes which acid and sulphites are especially deleterious to the water of water courses,
by neutralization and precipitation of the same with lime and by subsequently blowing
air and carbonic acid there-through.
D
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