IMPROVEMENTS IN TREATING BYE-PRODUCTS ARISING IN THE MANUFACTURE OF SODA AND POTASH FOR THE OBTAINMENT OF ANTICHLORES AND OTHER USEFUL PRODUCTS
Year: 1860

page_text: LETTERS PATENT to Joseph Townsend, Manufacturing Chemist, and
James Walker. Analytical Chemist, both of Glasgow, in the County of
Lanark, North Britain, for the Invention of "IMPROVEMENTS IN TREATING
BYE-PRODUCTS ARISING IN THE MANUFACTURE OF SODA AND POTASH FOR THE
OBTAINMENT OF ANTICHLORES AND OTHER USEFUL PRODUCTS."
Sealed the 4th June 1861, and dated the 11th December 1860.
PROVISIONAL SPECIFICATION left by the said Joseph Townsend and
James Walker at the Office of the Commissioners of Patents, with
their Petition, on the 11th December 1860.
We, JOSEPH TOWNSEND, Manufacturing Chemist, and JAMES WALKER,
Analytical Chemist, both of Glasgow, in the County of Lanark, North
Britain, do hereby declare the nature of the said Invention of "IMPROVEMENTS
IN TREATING BYE-PRODUCTS ARISING IN THE MANUFACTURE OF SODA AND POTASH FOR
THE OBTAINMENT OF ANTICHLORES AND OTHER USEFUL PRODUCTS," to be as follows,
that is to say-
Our said Invention relates to the utilizing of the bye or waste products
resulting in the manufacture of the carbonates of potash and soda, with the
view of obtaining a peculiar product, which we shall call " "precipitated
antichlore," also certain alkaline and earthy sulphites and hyposulphites, and
sulphur, and oxides of manganese.

page_text: The product named by us "precipitated antichlore" is obtained by the
following methods:-The soda or potash waste is lixiviated with water in any
convenient manner, and the solution being drawn off is oxidized by exposure
to the action of the atmosphere. Various methods may be employed for
effecting the oxidation, but it is preferred to let the solution percolate through
a tower or column of coke, pumice stone, pebbles, or any other convenient
material, and at the same time to cause a current of atmospheric air to pass
upward through it. Should once running through be insufficient to complete
the oxidation, the liquor is run through a second or a third time until it is
fully oxidized, and this is known when it ceases to give a precipitate with
sulphate of copper. The oxidized solution thus obtained will consist essentially
of hyposulphite of lime, with variable quantities of sulphite and sulphate of
lime, and its specific gravity will be slightly increased. The next operation
consists in concentrating the oxidized solution to a specific gravity of 1-15, or
even higher. It is not, however, essential that the solution be concentrated
at this stage of the process, but it is preferred to do so, as on allowing it
afterwards to repose, a floculent impurity separates, and the liquid becomes
clarified. The clear liquor is run off, and a solution of sulphate of soda is
added until precipitation ceases. The precipitate is separated by draining or
filtering, and, when dried, is the product to which we have applied the name
"precipitated antichlore." It consists of sulphate of lime, with a sufficient
proportion of sulphite and hyposulphite of soda, or of sulphite and hypo-
sulphite of lime, to render it available for use as an antichlore in the manu-
facture of paper.
The proportion of sulphite and hyposulphite may be
increased or diminished by using strong or weak solutions. The supernatent
liquor contains hyposulphite of soda, which is obtained in the form of crystals
or in lumps by concentration in the usual manner. We also obtain " pre-
cipitated antichlore" by substituting for sulphate of soda any of the following
substances, sulphate of magnesia, sulphate of potash, or sulphate of ammonia,
in which cases the simultaneous products will be respectively hyposulphite of
magnesia, hyposulphite of potash, or hyposulphite of ammonia.
To obtain sulphite and hyposulphite of lime, the oxidized liquor (after being
freed from some impurities, in the manner already described,) is evaporated to
dryness, and the residue is sulphite and hyposulphite of lime, which may also
be used as an antichlore; or a concentrated solution of the oxidized liquor
will answer the same purpose, should it be considered desirable to avoid
complete evaporation.
The uses to which any of the foregoing products may be applied are as

page_text: antichlores in the manufacture of paper, as bleaching agents for woollen or
other animal fabrics or straw, as purifiers in the manufacture of sugar, and
for various other purposes for which sulphites and hyposulphites are or may be
employed.
To obtain sulphur and certain useful sulphides, the unoxidized liquor is
mixed with chloride of manganese, or the "still liquor" obtained as a hye-
product in the manufacture of chlorine, and these liquors may be treated in
three ways.
Firstly, the solutions may be mixed in such proportions that the resulting
precipitate will consist chiefly of sulphur. The proportions for this purpose
will vary according to the greater or less amount of free acid in the still
liquor. As a general rule, however, the proportions will be from one to one
and a half gallons of unoxidized liquor, specific gravity 1.05, to one gallon of
still liquor, specific gravity 1.20. It is known when enough of the unoxidized
liquor has been added by the precipitate beginning to assume a blackish
colour. The precipitate is separated by filtering or draining, and when dry
may be used as sulphur in the manufacture of sulphuric acid or for other
purposes. The supernatant liquor consists chiefly of the chlorides of man-
ganese and iron, and is so far in a fit state to be operated upon for recovering
or producing oxide of manganese. Sulphur may also be obtained nearly pure
by using the oxidized (instead of the unoxidized) liquor in this process, or a
slight modification thereof.
Secondly, the solutions may be so proportioned that the resulting pre-
cipitate will consist chiefly of free sulphur and sulphide of iron. The
proportions for this purpose will vary according to the amount of iron and
free acid in the still liquor, but as a general rule the proportions will be about
three to four gallons of unoxidized liquor to one gallon of still liquor. It is
known when enough of the unoxidized liquor has been added, by the precipitate
beginning to assume a buff or flesh colour, or the same thing may be ascer-
tained by filtering a little of the mixture, and adding a few drops of unoxidized
liquor to the filtrate; a flesh-coloured precipitate will be obtained when enough
of the unoxidized liquor has been added, but as long as the precipitate is
black it requires more. The next operation consists in separating the pre-
cipitate by draining or filtering, and when dry it may be used in the manu-
facture of sulphuric acid. The supernatant liquor is by this process obtained
free from iron and excess of acid, and consists chiefly of chloride of manganese
in a very suitable state to be operated upon with a view of obtaining pure
oxide of manganese.

page_text: Thirdly, the solutions may be so proportioned that the precipitate will
consist of free sulphur, sulphide of iron, and sulphide of manganese. The
proportion will in this case be about nine gallons of unoxidized liquor to one
gallon of still liquor, but it is preferred to add the unoxidized liquor until no
further precipitate is obtained. The precipitate is collected, drained upon
filters, and cut into cubes of two or three inches, which are dried at a tein-
perature not exceeding 250° Farenheit. The dried precipitate is then ready
to be used in the manufacture of sulphuric acid, which is, by preference,
effected in apparatus similar to that ordinarily employed in burning pyrites.
The residue, after being burnt, contains a considerable proportion of oxide of
manganese, which may be used in the manufacture of chlorine.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Tow. ad and James Walker in the Great Seal
Patent Office on the 11th June 1861.
TO ALL TO WHOM, THESE PRESENTS SHALL COME, we, JOSEPH
TOWNSEND, Manufacturing Chemist, and JAMES WALKER, Analytical Chemist,
both of Glasgow, in the County of Lanark, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of December, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto us, the said
Joseph Townsend and James Walker, Her special licence that we, the said
Joseph Townsend and James Walker, our executors, administrators, and
assigns, or such others as we, the said Joseph Townsend and James Walker,
our 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 TREATING
BYE-PRODUCTS ARISING IN THE MANUFACTURE OF SODA AND POTASH FOR THE
OBTAINMENT OF ANTICHLORES AND OTHER USEFUL PRODUCTS," upon the condition
(amongst others) that we, the said Joseph Townsend and James Walker,
our executors or administrators, by an instrument in writing under our, or
their, or one of their hands and seals, should particularly describe and ascer-

page_text: tain 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.
NOW KNOW YE, that we, the said Joseph Townsend and James Walker,
do hereby declare the nature of our 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:-
Our said Invention has for object the preparing of a peculiar product which
for the purpose of distinction we shall designate as "precipitated antichlore,"
and also the producing or obtaining of certain alkaline and earthly hypo-
sulphites and sulphites, as well as sulphur and oxides of manganese. In the
ordinary and well-known manufacture of carbonate of soda from sulphate of
soda, there is obtained or there arises a bye or waste product containing much
insoluble sulphide of calcium, and a similar product is obtained or arises in the
ordinary manufacture of carbonate of potash from sulphate of potash; and it is
these bye or waste products of which we make use in carrying out our said
Invention.
In carrying out our said Invention we prefer to use the bye or waste product
obtained in the said manufacture of carbonate of soda, and which is commonly
known as "soda waste," but the same mode of treatment is applicable to the
bye or waste product obtained in the said manufacture of carbonate of potash.
Soda waste as obtained by the ordinary process of lixiviating crude soda or
black ash contains much sulphide of calcium not soluble in water, but if such
waste be exposed to the atmosphere it absorbs oxygen therefrom, and
a portion of it becomes soluble in water. The proportion of the soluble
salts will depend upon the extent to which the oxidation of the waste
has been allowed to proceed. If it has been sparingly oxidised, the solution
obtained by lixiviating it will chiefly contain soluble sulphide of calcium,
but further oxidation will cause the sulphide of calcium to be converted
into hyposulphite and sulphite of lime, and if the exposure to the air be
continued for a sufficient length of time all the sulphide of calcium will
become oxidised. We thus obtain at various stages of the oxidation solutions
containing soluble sulphide of calcium, with varying quantities of byposulphite
and sulphite of lime until the oxidation is complete, when the solution contains
the latter salts only. To obtain the waste in the requisite state of oxidation
for our purpose we expose it in a state of dampness in heaps for some days to
the atmosphere, and we facilitate this process of oxidation by occasionally

page_text: turning over the heaps so as to expose fresh surfaces to the air, and we keep
the waste in a continual state of dampness by sprinkling it with water or with
a solution of sulphide of calcium, until by testing it we find it to contain little
or no sulphide. The fully-oxidised product being lixiviated with water yields
a solution of hyposulphite and sulphite of lime (the former salt predominating),
which we employ in carrying out our Invention, as herein-after described. If
we arrest the process of oxidation before its completion, and then lixiviate the
product with water, we obtain a yellow solution containing byposulphite and
sulphite of lime and soluble sulphide of calcium, the presence of the latter
being indicated by the yellow colour of the solution or by the solution becoming
black on the addition of a salt of copper or of lead. We convert this dissolved
sulphide of calcium into hyposulphite and sulphite of lime, by causing the
solution to absorb oxygen from atmospheric air. We effect such absorption of
oxygen by causing such solution containing sulphide of calcium, either mixed
or unmixed with hyposulphite and sulphite of lime, to percolate slowly through
a tower (which we call an oxidising tower), containing pieces of coke or other
suitable material, and admitting at the same time atmospheric air through
proper openings at the lower part of the tower. An apparatus similar to that
ordinarily used for the condensation of muriatic acid gas in the soda manu-
facture is well suited for this part of our Invention. The complete oxidation
of the sulphide of calcium may be effected by passing the solution repeatedly
through such oxidising tower, but we prefer to complete the oxidation in one
operation by regulating the passage of the solution through the said tower. The
oxidation may also be effected either wholly or in part by causing atmospheric
air to be propelled in small streams or bubbles, by means of an air pump or
blowing apparatus, through such solution containing sulphide of calcium. In
addition, the application of heat to the solution, by injection of steam or by
other means, facilitates the process of oxidation. The oxidised solution thus
obtained contains the same products or ingredients as a solution obtained by
lixiviating the oxidised soda waste already referred to. In the event of obtain-
ing a solution (either by passing through the oxidising tower or lixiviating soda
waste not fully oxidised) containing much hyposulphite and sulphite of lime,
and little sulphide of calcium, we prefer to remove the last portion of
soluble sulphide of calcium by adding to it a small quantity of sulphuric,
muriatic, or nitric acid, or a solution of a soluble salt of iron, manganese, zine,
copper, or alumina. In either case the effect produced by such addition will
be the formation of a precipitate and the decomposition of the soluble sulphide,
and when the precipitate has subsided the supernatant liquor will be found free

page_text: from soluble sulphide. Boiling facilitates very much the deposition of the
precipitate. The quantity of any of the before-mentioned solutions required
for removing the last portion of sulphide will vary according to the quantity of
sulphide remaining unoxidised; but in every case the addition of the precipitate
should be continued until the clear supernatant liquor ceases to give a black
precipitate on the addition of a solution of a salt of copper or of lead. When
the fully-oxidised solution contains a slight excess of acid (which it will usually
do when prepared by means of the oxidising tower or after treatment with any
of the acids or salts before mentioned), we neutralise it by the addition of a
small quantity of cream of lime or other suitable alkaline substance, and then
evaporate it until it obtains a specific gravity of about 1-25, when any insoluble
matter is allowed to subside, and a clarified solution containing hyposulphite
and sulphite of lime is thus obtained. We now run off this clear solution into
a suitable vessel, and add to it a solution of sulphate of soda of a specific
gravity of about 1-18, until the addition of more sulphate gives no further
precipitate. We prefer to have both solutions hot, as in that case the resulting
precipitate subsides more readily. By these means we obtain a solution of
hyposulphite and sulphite of soda, and a precipitate consisting of hydrated
sulphate of lime. After the subsidence of the precipitate, we run off the solu-
tion to be employed as herein-after described. The precipitate is generally found
to contain more alkaline or earthy byposulphite and sulphite than is necesary,
and we therefore wash it with water until not more than the requisite quantity
remains. In ordinary cases it is found suitable to retain from 2 to 5 per cent.
of these salts mixed with the precipitate. This precipitate when dried at a tem-
perature not exceeding 212° Fahrenheit constitutes the product which we have
herein-before designated as "precipitated antichlore." The product thus obtained
has been found highly valuable in the manufacture of paper, as the hydrated
sulphate of lime gives weight and body thereto, whilst the sulphurous com-
pounds act effectually for the destruction or neutralisation of any chlorine
present in the paper pulp. From the liquor and washings run off from the
precipitated antichlore, we obtain hyposulphite and sulphite of soda in the
form of crystals by concentrating them to a specific gravity of about 1·40;
such crystals may be further purified by subjecting them to a second or
third crystalising process, or we obtain the same salts (only containing less
water) in the form of lumps, by evaporating the solution to a specific gravity
of about 1'65, when it solidifies on cooling, and may be broken into lumps.
We also obtain "precipitated antichlore" by substituting for sulphate of soda
employed as a precipitant any of the following substances, namely, sulphate

page_text: of magnesia, sulphate of potash, or sulphate of ammonia, in which cases the
simultaneous products from the supernatant liquor and washings will be
respectively byposulphite and sulphite of magnesia, byposulphite and sulphite
of potash, and hyposulphite and sulphite of ammonia, and we effect the wash-
ing of the "precipitated antichlore," in the same manner as herein-before
described. We also obtain "precipitated antichlore" by substituting for
fully-oxidised liquor the partially-oxidised liquor, in which case the resulting
products will be "precipitated antichlore," and the sulphides of sodium, mag-
nesium, potassium, and ammonium respectively, either mixed or unmixed with
the corresponding hyposulphites. and sulphites. The supernatant liquor, or
dissolved portion, containing sulphide of sodium, magnesium, potassium, or
ammonium, we subject to any of the oxidising or purifying processes herein-
before described, so that such solution will contain byposulphite and sulphite
salts free from any admixture of sulphide. From this solution we obtain the
corresponding hyposulphite and sulphite-salt in the form of crystals or in lumps
by the methods herein-before described. The "precipitated antichlore," con-
taining in these cases a small quantity of alkaline or earthy sulphide, as well as
a small quantity of alkaline or earthy byposulphite and sulphite, is washed in
the manner herein-before described.
To obtain hyposulphite and sulphite of lime in the solid form, we take the
liquor containing these salts obtained either by oxidation or purification in the
manner herein-before described, and evaporate it to dryness. The residue,
consisting of hyposulphite and sulphite of lime, may also be used as an anti-
chlore, or the concentrated solution obtained before complete evaporation will
answer the same purpose.
It will be understood. from the foregoing description of the first portion of
our said Invention that our chief object is to obtain the following products :-
1st. From the fully or partially oxidised liquor we obtain, by means of any
of the sulphates before enumerated, "precipitated antichlore," and hyposulphite
and sulphite of soda, magnesia, potash, or ammonia respectively.
2nd. From the fully oxidised or purified liquor we obtain hyposulphite and
sulphite of lime.
From the insoluble residue left after lixiviation of the oxidised soda waste,
which still contains much sulphite of lime, we obtain sulphite of soda or potash
by boiling or steeping it with a solution of carbonate of or caustic soda or
potash, and then by the proper evaporation of the resulting solution we obtain
sulphite of soda or potash in the form of crystals or in lumps.
The uses to which any of the hyposulphites and sulphites herein-before

page_text: mentioned may be applied, are, firstly, as antichlores in the manufacture of
paper or in the treatment of cotton or other fabrics; after bleaching with
chlorine or with compounds of that substance; secondly, as bleaching agents
for woollen or other animal fabrics or straw, stareli, oils, ivory, bone, and hair;
and, thirdly, as purifiers and anti-ferments in the manufacture of sugar.
To obtain sulphur and certain useful sulphides, the aforesaid solution of
sulphide of calcium, which for distinction we will call "unoxidised liquor," is
mixed with chloride of manganese, or with the still liquor resulting as a bye-
product in the manufacture of chlorine, and these liquors may be treated in
three ways.
Firstly, the solutions may be mixed in such proportions that the
resulting precipitate will consist chiefly. of sulphur. The proportions for
this purpose will vary according to the greater or less amount of free acid
in the still liquor; as a general rule, however, the proportions will be from
one to one and a half gallons of unoxidised liquor, specific gravity 1.05, to one
gallon of still liquor, specific gravity 1.20. It is known when enough of the
unoxidised liquor has been added, by the precipitate beginning to assume a
blackish color. The precipitate is separated by filtering or draining, and
when dry, may be used as sulphur in the manufacture of sulphuric acid or for
other purposes. The supernatant liquor consists chiefly of a solution of the
chlorides of manganese and iron, and is so far in a fit state to be operated
upon for recovering or producing oxides of manganese. Sulphur may also be
obtained by applying this process to the oxidised instead of the unoxidised
liquor.
Secondly, the solutions may be so proportioned that the resulting pre-
cipitate will consist chiefly of free sulphur and sulphide of iron. The
proportions for this purpose, though liable to vary according to the amount
of iron and free acid in the still liquor, will, as a general rule, be about three
to four gallons of unoxidised liquor, specific gravity 1.05, to one gallon of
still liquor, specific gravity 1-20. It is known when enough of the unoxidised
liquor has been added by the precipitate beginning to assume a buff or flesh
color, or the same thing may be ascertained with certainty by filtering a little
of the mixture, and adding a few drops of unoxidised liquor to the filtrate, the
separation of a flesh-colored precipitate shewing when enough of the un-
oxidised liquor has been added, but the formation of a black precipitate that
more is required. The next operation consists in separating the precipitate by
draining or filtering, and when dried it may be used in the manufacture of
sulphuric acid or for other purposes. By this process the supernatant.liquor is

page_text: obtained free from iron and excess of acid, and consists chiefly of chloride of
manganese in a very suitable state for obtaining oxides of manganese free from
iron.
Thirdly, the solutions may be so proportioned that the precipitate will
consist of free sulphur, sulphide of iron, and sulphide of manganese. The
proportions will in this case be about nine gallons of unoxidised liquor, specific
gravity 1.05, to one gallon of still liquor, specific gravity 1.20, but it is pre-
ferred to add the unoxidised liquor until no further-precipitate is obtained.
The precipitate is collected, drained upon filters, and cut into cubes of two or
three inches, which are dried at a temperature not exceeding 250° Fahrenheit.
The dried precipitate is then ready to be used in the manufacture of sulphuric
acid, which is by preference effected in an apparatus similar to that ordinarily
employed in burning pyrites. The residue after being burned contains a
considerable proportion of oxide of manganese, which may be used in the
manufacture of chlorine.
Having thus particularly described the nature of our said Invention, and the
manner in which the same is or may be used or carried into effect, we have to
state that we do not restrict ourselves to the precise details herein-before
described, as such may be varied and modified without departing from the
principle of our Invention, and that we do not claim to have invented every
separate detail herein-before described or referred to; but that what we con-
sider to be new and original, and claim as the Invention secured to us by the
berein-before in part recited Letters Patent is,-
First, the producing of hyposulphite and sulphite of lime from solutions of
sulphide of calcium obtained from the bye-products arising in the manufacture
of soda and potash, by causing such dissolved sulphide of calcium to become
oxidised by means of atmospheric air applied substantially in the manner
herein-before described.
Second, the using of hyposulphite and sulphite of lime obtained by any of
the methods herein-before described, together with sulphate of soda, sulphate
of potash, sulphate of ammonia, or sulphate of magnesia, or mixtures of such
sulphates, for producing "precipitated antichlore" substantially as herein-before
described.
Third, the using of "precipitated antichlore," such as is obtained by the
processes herein-before described in the manufacture of paper.
Fourth, the producing of hyposulphite and sulphite of soda, potash,
ammonia, or magnesia, or mixtures of such hyposulphites and sulphites, sub-
stantially in the manners herein-before described.
'

page_text: Fifth, the producing of sulphite of soda or potash by treating the insoluble
portion of the oxidised waste with carbonate of or caustic soda or potash,
substantially in the manner herein-before described.
Sixth, the obtaining of sulphur and oxides of manganese from solutions of
sulphide of calcium and solutions of chloride of manganese, by treating them
substantially in the manner herein-before described.
In witness whereof, we, the said Joseph Townsend and James Walker,
have hereunto set our hands and seals, this Eighth day of June,
in the year of our Lord One thousand eight hundred and sixty-one.
Witness,
EDMUND HUNT,
Patent Agent,
28, St. Enoch Square,
Glasgow.
JOSEPH TOWNSEND. (L.S.)
JAS. WALKER.
(L.S.)