IMPROVEMENTS IN OBTAINING Sulphur and SULPHUROUS ACID FROM ALKALI WASTE
Year: 1863

page_text: LETTERS PATENT to Ludwig Mond, of Appleton, in Widness, in the
County of Lancaster, Chemist, for the Invention of "IMPROVEMENTS IN
OBTAINING Sulphur and SULPHUROUS ACID FROM ALKALI WASTE."
PROVISIONAL SPECIFICATION left by the said Ludwig Mond at the
Office of the Commissioners of Patents, with his Petition, on the 8th
September 1868.
I, LUDWIG MOND, of Appleton, in Widness, in the County of Lancaster,
Chemist, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN OBTAINING SULPHUR AND SULPHUROUS ACID FROM ALKALI WASTE," " to
be as follows:-
My Invention consists in causing a current of air to be driven or drawn
through the alkali waste by mechanical power, for which purpose I can.employ
a fan, chimney, or other known means whereby currents of air are drawn or
driven. This treatment produces a soluble compound of sulphur, which I then
wash out and evaporate to dryness, subsequently distilling the residuum,
whereby sulphur is obtained. Or the solutions are decomposed by muriatiq
acid, or other known means, so as to produce sulphur and sulphurous acid gas.
In order that the air may circulate through the mass of waste the waste is
exposed in any suitable vessel or tower, but I propose when convenient to use
the vat in which the said waste has been produced, so that the operation may
be conducted without moving it. After the above-mentioned treatment with

page_text: air has been continued for a time a certain quantity, say about five per cent.,
of sulphur has been rendered soluble; this having been washed out, air is
again passed through the mass, and a further quantity obtained, and so on
until the waste is exhausted. The air may be used cold, but I propose to
heat it before passing it through the waste. My present experience, however,
indicates that the temperature should be limited, and I have found that a
range of from 120° to 150° F. produces the best result. I also propose to
mix carbonic acid gas and steam of water with the air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Ludwig Mond in the Great Seal Patent Office on the 8th
March 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, LUDWIG
MOND, of Appleton, in Widness, in the County of Lancaster, 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 sixty-three, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Ludwig Mond, Her special license that I, the said Ludwig Mond, my
executors, administrators, and assigns, or such others as I, the said Ludwig
Mond, 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
Island, and Isle of Man, an Invention for "IMPROVEMENTS IN OBTAINING
SULPHUR AND SULPHUROUS ACID FROM ALKALI WASTE," upon the condition,
amongst others, that I, the said Ludwig Mond, by an instrument in
writing under ny hand and seal, should particularly describe and ascer-
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 with six calendar month next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Ludwig Mond, 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 following state-
ment, that is to say:-

page_text: In obtaining sulphur and sulphurous acid from alkali waste it has been
proposed to spread the said waste in shallow layers upon shelves or other such
surfaces, and to depend upon the air which passes over the material for
effecting the conversion necessary for obtaining the required substances, but
this operation has been found to be inconveniently slow and imperfect.
According to my Invention I place the material in suitable vessels and
cause a current of air to be drawn or forced through the mass, so that an
intimate connexion takes place. This current of air may be cold or heated,
and may be mixed with the steam of water or with a small quantity of acid
gas, as, for instance, carbonic acid. The vessel or vessels in which the
operation constituting my Invention is conducted may be applied expressly for
that purpose, or they may be those in which the ordinary lixiviation of the
"black ash" has been conducted, so that the extraction of sulphur from the
waste may be effected without a removal thereof.
Having thus pointed out the main features of my Invention, I will proceed
to describe the method I prefer in carrying the same into practical operation.
In place of the set of four vats generally in use for lixiviating the "black
ash "I employ a set of twelve, four of which are always filled with black ash
in the process of lixiviation, and the remaining eight with waste to be operated
upon according to my Invention. The lower parts of all the vats are connected
with a fan capable of propelling about three cubic feet of air per minute for
every hundredweight of dry waste, and at a pressure of about four to seven
inches of water. The air before entering the fan passes through pipes placed
in a furnace flue or other heating apparatus. These pipes are provided with
openings capable of being closed or opened at pleasure, so as to admit any
desired amount of cold air, and thus to regulate the temperature; and a small
quantity.of carbonic or other acid gas may be added advantageously to the air,
but this quantity must be so regulated that no sulphuretted hydrogen is given.
off from the waste. As soon as the "black ash" is completely spent, and the
weak liquor well drained off, the connexion with the fan is opened and air
driven through the waste for about eighteen hours. When liquors containing
a comparatively large amount of sulphides are desired the air is to be used
cold or of a low temperature, and to be driven through the waste at a
moderate speed. When, however, liquors are required containing a small
amount of sulphides and a large amount of hyposulphites, the air is to be used
botter and at a greater speed, but in each case the temperature of the waste
should be kept between 120° and 200° F. This treatment having been
continued for the period mentioned the waste is lixiviated with hot water until
he soluble compounds are-washed out, which operation can readily .be -per-

page_text: formed in twelve hours. The weaker liquors of one yat are passed through
the next one in course of lixiviation, and so on through the whole set so as to
obtain only strong liquors. When this lixiviation is finished air is again
passed through. the waste and the material again lixiviated, and the like
operations may be conducted a third time. By the above treatment I find
that sulphur equal to about twelve per cent, of the weight of the salt cake
used in making the "black ash" is obtained in solution in about four days;
the spent waste is now cast out of the vat which is again filled with "black
ash" to be treated as before.
I have above described the operation of my Invention by which sulphur in
solution is recovered from alkali waste, and the liquor thus obtained be
may
utilized by any known method. I will, however, describe a process which
may be beneficially adopted..
The liquor above mentioned being previously treated with sulphurous acid
and heated to the boiling point by steam. is decomposed in wooden generators
by muriatic acid or any other acid liquor, for instance, the waste liquor from
bleaching powder stills. I combine two of these generators in such a manner
that the sulphurous acid evolved in the one in course of decomposition is
made to pass through the other which is filled with the original liquor, and so
connected that the escaping gases shall enter a vitriol chamber. By these
means all the sulphides in the solutions are converted into hyposulphites, the
quanty of the obtainable solid sulphur is increased, and the evolution of
sulphuretted hydrogen is avoided. The muriatic acid is to be added by
degrees to the so prepared heated liquor until in slight excess, and steam
being then introduced is continued until all the sulphurous acid is.driven off;
a quantity of the original liquor containing sulphide is then added to the
liquid until there is a slight excess of sulphide, and then again steam and
muriatic acid are passed in until there is a slight excess of the latter. By this
treatment a quantity of sulphur which would otherwise be lost in the form of
pentathionic acid is obtained. The sulphur thus precipitated settles very
rapidly to the bottom of the generators, and may be washed and used after
any ordinary manner.
I have in describing the means by which my Invention may be carried into
effect mentioned. a fan as being employed for causing a current of air pure or
mixed with gases. to pass through the mass of waste, but it will be obvions
that the same end may be attained by using the draft of a chimney by a
pump, or by other well-known agents. I have also mentioned certain quan-
tities, degrees of temperature, and other such particulars, but for all these
there is a range which will be readily ascertained by competent persons, the

page_text: said particulars being given merely as a guide, and to point out details which
I have found to answer the end in view.
Having thus described and ascertained the nature of my said Invention,
and the manner of carrying the same into effect, I desire it to be understood
that I claim as secured to me under the above in part recited Letters Patent
and for the purpose above set forth,-
Firstly, causing a current of air or air mixed with acid gases.or steam, either
heated or cold, to be drawn or driven through the mass of waste.
Secondly, performing the said operation in the same vessel in which the
usual lixiviation of the "black ash" has been effected.
In witness thereof, I, the said Ludwig Mond, have hereunto set my hand
and seal, this First day of March, in the year of our Lord One
thousand eight hundred and sixty-four.
LUDWIG MOND. (L.S.)