IMPROVEMENTS IN GRINDING AND SIEVING CAUSTIC ALKALIES AND IN APPARATUS THEREFOR
Year: 1879

page_text: LETTERS PATENT to William Jones Menzies, of St. Helen's, in the County of
Lancaster, Chemical Manufacturer, for the Invention of "IMPROVEMENTS IN
GRINDING AND SIEVING CAUSTIC ALKALIES AND IN APPARATUS THEREFOR."
Sealed the 9th January 1880, and dated the 21st October 1879.
PROVISIONAL SPECIFICATION left by the said William Jones Menzies at the
Office of the Commissioners of Patents on the 21st October 1879.
WILLIAM JONES MENZIES, of St. Helen's, in the County of Lancaster, Chemical
Manufacturer. "IMPROVEMENTS IN GRINDING AND SIEVING CAUSTIC ALKALIES AND
IN APPARATUS THEREFOR."
In grinding caustic alkalies great difficulty is experienced, owing to their
deliquescent nature and the annoyance experienced from the fearfully corrosive
dust flying about.
This has hitherto almost prevented these chemicals being ground to a commercial
extent, though they are vastly more convenient if finely and evenly comminuted.
I find however that by grinding them while hot the deliquescence is not per-
ceptible, and by grinding and immediately sieving in a closed mill the dust
nuisance is minimised. I therefore pour out the melted caustic on to metal plates,
and when consolidated, but still at a high temperature, pass them through the mill,
preferably an ordinary grinding and sieving clay mill, but covered in below with
a stationary bottom underneath, and scraper moving round upon it and scraping
the sieved and powdered alkali (which has fallen through the sieve plates above on
to the bottom of the closed chamber below) out through apertures at the bottom
into the barrels placed underneath; or if the caustic has been allowed to cool I
beat the mill and atmosphere in connection with it with steam pipes or other
mechanical means of heating. Many other forms of combined sieve and grinder
will do so long as the sieving immediately follows the grinding, and the surrounding
atmosphere is excluded and kept heated either by the caustic alkali being ground
hot, or the mill and apparatus heated by steam pipes, or other means of heating
applied.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Jones Menzies in the Great Seal Patent Office on the 21st
April 1880.
"
WILLIAM JONES MENZIES, of St. Helen's, in the County of Lancaster, Chemical
Manufacturer. IMPROVEMENTS IN GRINDING AND SIEVING CAUSTIC ALKALIES AND
IN APPARATUS THEREFOR."
In grinding caustic alkalies great difficulty is experienced, owing to their
deliquescent nature and the annoyance experienced from the fearfully corrosive dust
flying about.
This has hitherto almost prevented these chemicals being ground to a commercial
extent, though they are vastly more convenient if finely and evenly comminuted.
I find however that by grinding them while hot the deliquescence is not per-
ceptible, and by grinding and immediately sieving in a closed mill the dust nuisance
is minimized. I therefore pour out the melted caustic onto metal plates, and when
consolidated, but still at a high temperature, pass them through the mill, preferably
an ordinary grinding and sieving clay mill, but covered in below with a stationary
bottom underneath, and scraper moving round upon it and scraping the sieved and
powdered alkali (which has fallen through the sieve plates above onto the bottom
of the closed chamber below) out through apertures at the bottom into the barrels
placed underneath; or if the caustic has been allowed to cool I beat the mill and
atmosphere in connection with it with steam pipes or other mechanical means of
heating. Many other forms of combined sieve and grinder will do, so long as the
sieving immediately follows the grinding, and the surrounding atmosphere is
excluded and kept heated either by the caustic alkali being ground hot, or the mill
and apparatus heated by steam pipes, or other means of heating applied.
In the Drawings annexed Fig. 1 is an elevation, Fig. 2 section of my improved
apparatus. A, A, are the grinding rollers, as in an ordinary mortar or clay mill;
B, shaft carrying same; a, a, scrapers bearing against periphery of rollers A, A;
C, steel or other hard plate carried by cast-iron pan D, which latter is keyed to
shaft E, and rotated by bevil gearing F, G, fly-wheel H, crank I, and engine J;
K, walls of pan; L, grating; M, stationary bottom; N, scrapers, scraping the finely
powdered and sieved caustic that falls on the shut in bottom M into spout P in
said bottom, through which the powder falls into a barrel Q, preferably placed on
a trolly as shown.
In actual practice I use caustic sufficiently hot and guard it from currents of air,
and pass through such a quantity in such manner as to avoid having to heat the
mill with steam pipes, et cetera; but if desirable the pan could be made hollow and
steam be made to circulate between the plates, or steam pipes could be laid in the
circular trough or bottom M. It will be seen too that, as represented, the rotation
of the pan causes the rollers to revolve; if desirable independent driving apparatus
could be applied to the rollers, so as to cause them to rotate at a different surface
speed to that of the pan.
Having now described my Invention and the best mode known to me of
carrying it into effect, I wish it to be understood that what I believe to be new
and desire to protect under the herein before in part recited Letters Patent is,―
First. The manufacture of ground or powdered caustic alkali by grinding it in
the heated state, or in such manner that while undergoing the grinding operation
either the alkali itself or the apparatus and air contained therein may be sufficiently
hot to resist the action upon the alkali of aqueous vapour in the air.

page_text: Second. The manufacture and use of apparatus for grinding caustic potash or
caustic soda, constructed substantially as above described.
In witness whereof, I, the said William Jones Menzies, have hereunto set my
hand and seal, this Nineteenth day of April, in the year of our Lord One
thousand eight hundred and eighty.
Witness,
WILLIAM PHILLIPS THOMPSON,
of W. P. Thompson & Co.,
Patent Agents,
6, Lord Street, Liverpool,
& 323, High Holborn,
London, W.C.
W. J. MENZIES. (L.S.)