IMPROVEMENTS IN PURIFYING ALKALINE LEES
Year: 1858

page_text: LETTERS PATENT to Henry Deacon, of Widnes Dock, near Warrington,
in the County of Lancaster, Alkali Manufacturer, for the Invention of
"IMPROVEMENTS IN PURIFYING ALKALINE LEES."
PROVISIONAL SPECIFICATION left by the said Henry Deacon at the
Office of the Commissioners of Patents, with his Petition, on the
21st June 1858.
I, HENRY DEACON, of Widnes Dock, near Warrington, in the County of
Lancaster, Alkali Manufacturer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN PURIFYING ALKALINE LEES," to be as follows,
that is to say:-
This Invention relates to certain improved processes for purifying the
liquors or alkaline lees obtained in the manufacture of alkalis, such as soda
and potash.
The said processes consist, firstly, in adding hydrated protoxide of iron or
hydrated magnetic oxide of iron to such lees at any convenient temperature
not exceeding 130° of Fahrenheit's thermometer. Secondly, in separating
at any lower temperature than 130° Fahrenheit the precipitate produced in
and from such lees by the reaction at a higher temperature of any salt or
oxide of iron added thereto. Thirdly, in adding any salt or oxide of iron to

page_text: such lees in a state of concentration at or near their boiling points, and in
subsequently diluting them and separating the precipitate in the mode before
. described. Fourthly, in exposing the said lees after any salt or oxide of
iron, manganese, or zinc has been applied thereto to the action of atmo-
spheric air and agitation. Fifthly, in the prolonged application of temperatures
below 130° Fahrenheit to such lees when containing any ferro or ferri
cyanides. Sixthly, in the application of caustic lime or magnesia to the
precipitate produced by any salt or oxide of iron reacting on such lees for the
purpose of retarding the oxidation of the precipitate during the separation of
the alkali therefrom. And, seventhly, in roasting such precipitate when not
mixed with lime or magnesia with an alkaline chloride, so as to produce a.
corresponding alkaline sulphate, with the view of utilising such precipitate.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Deacon in the Great Seal Patent Office on the
21st December 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
DEACON, of Widnes Dock, near Warrington, in the County of Lancaster,
Alkali Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of June, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Henry Deacon, Her special license that I, the said Henry
Deacon, my executors, administrators, and assigns, or such others as I, the
said Henry Deacon, my executors, administrators, or 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
PURIFYING ALKALINE LEES," upon the condition (amongst others) that I, the
said Henry Deacon, by an instrument in writing under my hand and seal,
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 Henry Deacon, do hereby declare
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 fol-
lowing statement, that is to say:-
This Invention relates to certain improved processes for purifying the
liquors or alkaline lees containing alkaline sulphides obtained in the manu-
facture of alkalies, such as soda and potash, or carbonates thereof.
The said processes consist, first, in adding hydrated protoxide of iron, or
hydrated peroxide or hydrated magnetic oxide of iron to such lees at any
convenient temperature not exceeding 130° of Fahrenheit's thermometer.
Secondly, in separating at any lower temperature than 130° Fahrenheit the
precipitate produced in and from such lees by the reaction at a higher tempe-
rature of any salt of iron except its sulphides, or of any oxide of iron when
added thereto; and when the term "salt" or "metallic salt" is used herein, I
mean such compounds of iron, manganese, and zinc, not being sulphides, as
are well known to chemists as salts of iron, manganese, and zinc, as chlorides,
sulphates, &c., &c.; and of such salts I prefer the basic sesqui-chloride
of iron. Thirdly, in adding any salt of iron or oxide of iron to such lees in a
state of concentration at or near their boiling points, and in subsequently
diluting them and separating the precipitate in the mode herein-before
described. Fourthly, in exposing the said lees after any salt or oxide of iron,
manganese, or zinc has been applied thereto to the action of atmospheric air
and agitation. Fifthly, in the prolonged application of temperatures below
130° Fahrenheit to such lees when containing any ferro or ferri cyanides.
Sixthly, in the admixture of caustic lime or magnesia to the precipitate pro-
duced by any herein-before mentioned metallic salt or oxide reacting on such
lees, for the purpose of retarding the oxidation of the precipitate during the
separation of the alkaline lees therefrom. And, seventhly, in roasting such
precipitate when not mixed with lime or magnesia with an alkaline chloride,
so as to produce a corresponding alkaline sulphate, with the view of utilizing.
such precipitate.
The purification of alkaline lees herein referred to, consists mainly in the
formation of precipitates of metallic sulphides by the mutual reaction of the.
metals or their oxides and salts (not being sulphides) herein referred to, and
the alkaline sulphides existing in the lees resulting from the lixiviation of
black ash, or of sulphides of sodium or potassium, and the precipitate being.
allowed to subside, the purified liquor may be removed, or the precipitate and
the solution may be separated in any other convenient manner. The various
metallic oxides and insoluble metallic salts should be in as fine a state of

page_text: division as they can conveniently be procured, and the soluble metallic salts
are more conveniently applied in solution in water. I find that one equivalent
of a protoxide of iron, manganese, or zinc, or of a protosalt of iron, manganese,
or zinc, will decompose one equivalent of alkaline sulphide in the said lees,
producing precipitates of the corresponding metallic protosulphides, and that
the sesquioxides and sesquisalts of iron produce precipitates of sesquisulphide
of iron, and its magnetic oxide and salts thereof produce corresponding
precipitates of magnetic sulphides, but the binoxide of manganese I find
produces in such lees precipitate of sulphide of manganese, and oxidises a
proportionate amount of alkaline sulphide. I apportion the quantities of the
metallic oxides or metallic salts employed in purifying the said lees from
alkaline sulphides in conformity with the results just enumerated, preferring
always to add a slight excess of such metallic oxides or salts. But I do not
find that any of the said metallic oxides or salts, either alone or in combina-
tion, are capable of so purifying such lees that they will not give a colored
precipitate with the salts of lead either immediately or in the course of a short
time; such entire purification, if required, must be completed by additional
means, such, for instance, as those indicated under the fourth head of this
Invention, or by the addition of chloride of lime or other suitable oxydizing
agent. The salts and oxide of zinc give the lightest colored less, but their
employment is expensive; the hydrated sesquioxide of iron applied at tempe-
ratures below 130° and otherwise, as directed under the fourth head of this
Invention, is the material I prefer; the oxides and salts of manganese are the
most objectionable, because of the amount of manganese retained in solution,
and the magnetic oxides and salts of the magnetic oxides of iron give the
darkest coloured lees. With these considerations the value of the various
oxides and salts, for the purpose of effecting the purification of the lees, can,
in other respects, be easily determined by the practical man, from their relative
price and other local circumstances, and as all the metallic oxides and salts
before mentioned are well known, it is unnecessary more particularly to
describe their production or properties. The native ores or oxides of iron,
zine, or manganese may be used if not containing any material known to be
objectionable. Alumina, if present, is more or less dissolved by the lees, but
in other respects it is slightly beneficial. It may be remarked that the
removal from or the oxidation of alkaline sulphides in alkaline lees facilitates
the crystalization of the chrystalizable salts remaining in the said lees.
In carrying out the first part of this Invention, I prefer to use the hydrated
sesquioxide of iron, and I find a temperature of 70° to 80° usually a con-
venient heat, and about 45° Twaddle, a convenient strength, but the lower the

page_text: temperature, and the weaker the lees, the more complete is the separation of the
precipitate, both in this and in all other cases herein described and referred to:
In carrying out the second portion of my Invention, I prefer to use the
hydrated sesquioxide of iron, and after cooling the heated lees I proceed as
previously described to separate the precipitate, and as the application of heat
whilst the metallic oxides or salts or sulphides remain in the lees tends to render
the lees of a darker colour, I employ beat only when it is desirable to hasten the
reaction of oxides or salts, which in the cold may from some cause be acted
upon with difficulty. I prefer to employ the third portion of my Invention
only when it is necessary to use the anhydrous metallic oxides and insoluble
metallic salts. If the lees contain a large proportion of carbonated alkalies,
the reaction is comparitively slow, as in order to obtain rapid and efficient
action, a temperature of about 260° is desirable, and to obtain this temperature,
the lees must contain much caustic alkali or be heated under pressure, which
latter operation is generally very inconvenient. The lees being raised to the
necessary temperature, I prefer that they should be in a state of ebullition, as
the agitation facilitates the reaction; I add the metallic substances before
mentioned or any of them, preferring the sesquioxide of iron, and after the
reaction appears to be complete, I cool the lees to any convenient temperature
under 130° Fahrenheit, say 80° or 90° Fahrenheit, and I prefer that this
should be effected as quickly as possible. Should the lees be stronger than 45°
or 50° of Twaddle, I dilute them to about those strengths as rapidly and with
water as cold as possible, as the sudden change of temperature greatly
facilitates the separation of the precipitate.
In carrying out the fourth portion of my Invention, I prefer to agitate the
lees with any of the various metallic oxides or salts herein described, until the
reaction is complete, and the metallic sulphides are produced. I then separate
them from the lees as perfectly as possible, and I again agitate the lees, but in
contact at the same time with atmospheric air; the agitation, in the first
instance, being principally of service when the said lees are not boiled with
the said metallic salts or oxides, but the agitation and simultaneous exposure
to atmospheric air being equally applicable in all cases after as complete a
separation as possible of the metallic sulphides has been effected in order that
their subsequent oxidation may be prevented. I would remark that the
various metallic oxides and salts herein mentioned have long before been
proposed for the purification of alkalinė lees from alkaline sulphides, but I
know of no method now or heretofore in use or bitherto described, by which
the said processes can be practically carried out. In many of the methods
alluded to, it is directed to mix the lecs and metallic oxides or salts by,

page_text: agitation, and although in all the methods alluded to, as well as in those
herein-before alluded to, as well as in those herein-before described, agitation
is essentially necessary, yet no measure or means of determining the amount
of agitation necessary is afforded. I find that for economy of material
employed, for rapidity of execution, and for the efficiency of the result, such
agitation to be most important. The agitation that a man is able to effect in
any of the vessels ordinarily employed in the manufacture of alkali, namely,
carbonate of soda on the large scale, is of very little service. The amount of
agitation I consider desirable is at least equal to the agitation found requisite
to obtain butter from milk or cream by churning, and the more rapidly the
mixture of lees and metallic salts and oxides are agitated after admixture the
better, and especially so with the sesquioxide and sesquisalts of iron, which
are otherwise apt to be partially reduced and to discolour the lees. The
agitation should be continued until no more of the alkaline sulphide is
decomposed. The metallic sulphides are then separated from the cool lees as
herein described. The lees separated therefrom are again to be agitated with
about the same violence, but also with free exposure to atmospheric air, and
the lees should be as hot as possible during this operation. Any iron or
manganese or alkaline or other sulphides in the solution are thus oxidised, and
the greater proportion if not the whole of the metallic oxides are rendered
insoluble, and may be removed when the lees are not stronger than about 50°
Twaddle, and are allowed to cool below 130° Fahrenheit. Any convenient
mode of forcing or sucking air through the hot lees may be adopted, or a
current of air may be made to pass through what may be termed "the churning
vessel," but I prefer forcing numerous streams of air through the hot lees by
such evident modifications of the Invention, for which Letters Patent were
granted to William Godfrey Kneller, on or about the Twenty-second day of
December, 1842, as may appear best to meet the requirements of the
individual case under consideration. This exposure to air should be continued
until no discoloration is produced by the addition of a salt of lead to a portion
of the lees; the precipitates produced must of course be separated as herein
described, or in any convenient manner.
The fifth portion of my Invention depends on the reaction of alkaline
sulphides on ferro or ferri cyanides, (all of which are almost invariably present
in the lees obtained from the lixiviation of "black ash" or crude alkalies,)
whereby a precipitate containing sulphur and iron is formed. This reaction
is hastened by the application of a moderate degree of heat not exceeding 130°;
in practice I find a temperature of about 100° to be most desirable. The
time necessary to effect such results appears to be capricious, and often varies

page_text: from 24 hours to a week or more.
After a period, however, the reaction will
be complete, and a lye will be obtained, from which perfectly white chrystals
and alkaline salts may be obtained, but which lye will contain nearly as much
alkaline sulphides as at first, (i. e., this method of purification does not remove
them.)
In carrying out the sixth part of my Invention, I add caustic lime or
magnesia (preferring lime) to the metallic sulphides produced before washing
all the alkaline lees therefrom. I find that the oxidation of the said sulphides
is retarded by their being associated with an alkali or alkaline earth, as caustic
or quick lime. In practice an equivalent of magnesia or lime to an equivalent
of the metallic sulphide will be found sufficient for such purpose. The lime
or magnesia should be added before the washings are reduced below 15°.
Twaddle, but the lime or magnesia should not be added before the precipitate
of metallic sulphides is produced, or a combination of the metallic oxides with
the earths may be produced, which will prevent the reaction desired. If the
lime or magnesia is added before the precipitate has subsided they will often
assist it to subside.
In carrying out the seventh portion of my Invention, I separate by any
of the ordinary means the lees from the metallic sulphides as perfectly.
as possible, and with the least possible oxidation of the sulphides, and
I mix the metallic sulphides thus obtained with an alkaline chloride, and
roast or otherwise oxidise the mixture in the ordinary manner of roasting or
oxidising mixtures of metallic sulphides with alkaline chlorides in order to
obtain the corresponding alkaline sulphates, and I proceed with the further
manufacture of such sulphates as usual. The anbydrous metallic oxides thus
obtained may be again used for purifying other lees as herein-before described.
until the gradual accumulation of impurities unfit the oxides for further
service.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as variations may be made therefrom without deviating
from the principles or main features of my said Invention; but what I consider
to be novel and original, and therefore claim as the Invention secured to me
by the herein-before in part recited Letters Patent is,―
First, adding at any convenient temperature not exceeding 130° Fahrenheit,
hydrated protoxide, hydrated peroxide, or hydrated magnetic oxide of iron to
alkaline lees obtained or resulting in the manufacture of alkalies, such as soda
:

page_text: or potash, or carbonates thereof, either by the method now generally adopted,
or by any modification of Le Blanc's process, in order to decompose the
alkaline sulphides existing in such lees...
Second, in separating at any lower temperature than 130° Fahrenheit, the
precipitate of metallic sulphides produced in and from such lees by the reaction
at a higher temperature of any salt or oxide of iron when added thereto.
Third, in adding any salt or oxide of iron to such herein-before mentioned
lees when in a state of concentration at or near their boiling points, and in
subsequently diluting them with water, and separating the precipitate of
metallic sulphide in the manner herein-before mentioned.
Fourth, submitting a mixture of alkaline lees, and any salt or oxide of iron,
manganese, or zinc to agitation, in manner and for the purpose as herein-
before mentioned.
Fifth, exposing alkaline lees after any salt or oxide of iron, manganese, or
zinc has been added thereto to the combined action of atmospheric air and
agitation.
Sixth, the prolonged application of a temperature below 130° Fahrenheit,
to alkaline lees, when containing any ferro or ferri cyanides of the alkaline
earths or metals, for the purpose herein-before mentioned.
Seventh, in the admixture of caustic lime or magnesia with the precipitated
metallic sulphide produced by the reaction of any herein-before mentioned
metallic salt or oxide on such before-mentioned alkaline lees, for the purpose
of retarding the oxidation of such precipitate, during the separation of the
purified alkaline solution therefrom.
Eighth, in roasting or oxidising such precipitated metallic sulphide when
not mixed with lime or magnesia, with an alkaline chloride, so as to produce a
corresponding alkaline sulphate with a view of further utilising such resulting
alkaline sulphate.
In witness whereof, I, the said Henry Deacon, have hereunto set my
hand and seal, this Eighteenth day of December, One thousand eight
hundred and fifty-eight.
HENRY DEACON. (L.S.)