IMPROVEMENTS IN THE PRODUCTION OF SULPIATE OF POTASH FOR THE MANUFACTURE OF ALUM
Year: 1876

page_text: LETTERS PATENT to Peter Spence, of Manchester, in the County of Lan.
caster, Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN
THE PRODUCTION OF SULPIATE OF POTASH FOR THE MANUFACTURE OF ALUM."
Scaled the 21st July, 1876, and dated the 24th January, 1876
PROVISIONAL SPECIFICATION left by the said Peter Spence at the Office
of the Commissioners of Patents on the 24th January 1876.
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist. IMPROVEMENTS IN THE PRODUCTION OF SULPHATE OF POTASH
THE MANUFACTURE OF ALUM."
FOR
My Invention relates to improvements upon that method of manufacturing
sulphate of potush for which Letters Patent were granted to me, dated 15th
January, 1869, No. 130, and which patent 1 allowed to become void on account
of practical difficulties which arose in carrying out the manufacture, and
which niy present Invention is designed to overcome, and this end I accomplish
by keeping up the heat of the sulphuric acid in a suitable vessel and projecting
into the same the muriate of potash in small and regular quantities.
A method which may be employed is as follows:- use a vessel constructed
of suitable material and provide it with coils of piping capable of resisting
considerable pressure, and connect the said coils to a steam boiler, working at
say 50lbs. per square inch. Into this vessel I introduce sulphuric acid of a
strength from 16 up to 175, S.G., using of the said acid from two and a half
to three lines the weight of the muriate of potashi to be decomposed. Steam
being admitted to the coils the sulphuric acid is heated to about 240° F, and
the muriate of potash is now projected therein in small and regular quantities
by an archimedian screw or other suitable mechanical contrivance, and the
hydrochloric acid is quickly and continuously driven off into a suitable ordinary
condenser, and the heat which rises will eliminate the last portions. The pro-
portions of sulphuric acid and muriate of potash used are such that the product
is in a liquid form, and this I run off, to be applied as described in the Speci-
fication of my former l'atent aforesaid.
Instead of the coils of steam pipe above referred to fire heat may be em-
ployed, but I at present prefer the use of steam.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Peter Spence in the Great Seal Patent Office on the 24th July 1876.
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist. "IMPROVEMENTS IN THE PRODUCTION OF SULPHATE OF POTASH
THE MANUFACTURE OF ALUM."
FOR
My Invention consists in a method of converting muriate of potash into
sulphate of potash suitable for the manufacture of potash alum, it being an in-
provement upon that Invention for which Letters Patent were granted to me,
tiated Fifteenth January, One thousand eight hundred and sixty-nine, Number
130. To effect this conversion, instead of adding to a charge of muriate of
potash just sufficient sulphuric acid to combine with the potash and effecting
the decomposition by heat in the ordinary manner 1 proceed as follows:-I
employ a vessel, say about six feet deep, of any suitable material, but lined with
lead of considerable thickness, say sixteen pounds to twenty pounds per square
foot, and from the top of this vessel or still I carry a stoneware pipe, say one
foot in diameter to an ordinary tower for condensing hydrochloric acid as is well
known. Inside the vessel or still I introduce coils of lead pipe, say of one and
a half inch internal diameter, and of sufficient strength to resist at the least
fifty pounds per square inch. I now run sulphuric acid into the still, of the
strength of 120° Twaddle, or thereabout, in quantity equal to three times the
weight of muriate of potash to be operated on. I use this large excess of acid
because I find that if only enough be used to form bisulphate of potash the
product cannot be run out liquid from the still. I now heat up the acid by
blowing steam, of forty-five pounds or fifty pounds pressure, into the coils of
pipe, and as soon as the heat reaches 240° F., or thereabout, I put into operation
a mechanical arrangement by which 1 project through a small hole in the top
of the still small and regular charges of muriate of potash. The mechanical
apparatus may consist of any known arrangement used for feeding regular
supplies of material. These charges, of about a quarter of a pound each, are
delivered at the rate of about sixty to eighty per minute, so that in about threo
and a half hours I can charge the still with one ton and a half of muriate with-
out seriously reducing the temperature of the acid or causing any violent ex-
plosion. The steam in the coils being kept on, the greater part of the hydro-
chloric vapour is evolved from the charge almost instantly, and passes on to the
condensing tower, and being nearly pure hydrochloric vapour is easily and
perfectly condensed by a small stream of water into mercantile hydrochloric
acid. When all the muriate has been added the application of steam being con-
tinued the liquid rises to a temperature of 270° F., and I then find that the
hydrochloric acid is practically gone, the merest traces of it being left in the
solution. This solution of bisulphate of potash with an excess of acid I now
run direct into the shale pans, where solution of sulphate of alumina is being
formed, or direct into the coolers along with the said sulphate of alumina, and
thereby and in either case potash alum is produced. Or in place of this direct
process for making alum I can run the solution off into separate vessels and
allow it to crystallize for future use.
Having thus described and ascertained the nature of my said Invention, and
the manner in which the same is to be performed, I desire it to be understood
that I do not limit myself to the precise details above described, but claim as
secured to me under the above in part recited Letters Patent, and for the purpose
above set forth-
Firstly. The introduction of muriate of potash into heated sulphuric acid in
small charges, delivered in regular succession.
Secondly. The employment of the temperature of high pressure steam through
the medium of lead pipes, or equivalent arrangement for heating the acid and
muriate of potash.

page_text: Thirdly. The use of an excess of sulphuric acid over and above that required
to make bisulphate of potash
In witness whereof, I, the said Peter Spence, have hereunto set my hand
and seal, this Twenty-second day of July, in the year of our Lord, One
thousand eight hundred and seventy-six.
Dחירתו
DENCE
DETER
(LS.)