IMPROVEMENTS IN THE MANUFACTURE OF SULPHITE OE LIME
Year: 1879

page_text: LETTERS PATENT to Richard Powell, of Liverpool, in the County of Lancaster,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF SULPHITE
OE LIME"
Sealed the 8th June 1880, and dated the 13th December 1879.
PROVISIONAL SPECIFICATION left by the said Richard Powell at the Office
of the Commissioners of Patents on the 13th December 1879.
RICHARD POWELL, of Liverpool, in the County of Lancaster.
THE MANUFACTURE OF SULPHITE OF LIME"
"IMPROVEMENTS IN
This Invention consists in making the sulphite in the dry way instead of by a
wet process or double decomposition as hitherto. By this means a great saving is
effected and a more useful article obtained. I pass sulphurous oxide (SO) into
lime, whether hydrate, caustic, carbonate, or any other cheap salt of lime decom-
posable by sulphurous acid. The sulphurous oxide can be obtained by any of the
usual processes, such as the combustion of sulphur or pyrites or the decomposition
of sulphuric acid. The sulphurous oxide when formed is brought into contact with
lime in the most convenient way, either by passing the gas over the lime in a
closed chamber or through a long pipe or flue partially filled with lime.
Experimentally, I have used a small lead chamber, into which I passed the gas
onto hydrate of lime.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Richard Powell in the Great Seal Patent Office on the 12th June
1880.
RICHARD POWELL, of Liverpool, in the County of Lancaster.
THE MANUFACTURE OF SULPHITE OF LIME."
"IMPROVEMENTS IN
This Invention consists in making sulphite of lime by the dry method instead of
wet process or by double decomposition as heretofore practised, and by this means
a great saving is effected and a more useful article is obtained. I pass sulphurous
oxide (SO) onto lime, either caustic, hydrate, or carbonate, or onto any other
cheap salt of calcium decomposable by sulphurous acid. The sulphurous acid may
be obtained by any of the usual processes which may be found most convenient,
such as the combustion of sulphur or pyrites or the decomposition of sulphuric
acid. The sulphurous oxide when formed is brought into contact with the lime in
the most convenient way, either by passing the gas over the surface of the lime or
salt of calcium employed (which should be reduced to a fine powder) through a
series of leaden chambers, on the floor of which the lime or other salt of calcium,
preferably hydrate of lime, is strewed about three inches thick. This, when the
gas is obtained by the decomposition of vitriol, is, I consider, the preferable method,
the continued evolution of the gas forcing it forward from chamber to chamber, so
that the gas not absorbed in the first chamber is taken up by the lime in the
succeeding ones; the lime should be occassionally shifted or stirred, and the process
continued until the lime in the first chamber has been brought up to the necessary
strength. In most cases a strength of from sixty five to seventy five will be found
sufficient for ordinary mercantile sulphite. The sulphite of lime in this chamber
is then withdrawn for market, and the salts of calcium in the second chamber are then
exposed first to the gas either by moving the lime from chamber to chamber, which
is the better plan, and filling the last chamber with fresh hydrate, or by changing
the connections, so that No. 2 is the first chamber and No. 1 chamber, which has
fresh hydrate strewn on the floor, becomes the last.
Or instead of the above described arrangement the manufacture can be carried
on by strewing the hydrate of lime or other salt of calcium employed about three
inches thick on the bottom of a long leaden pipe or flue about one foot square, and
having doors or valves in it to stirr the lime through; this method is preferable
where the sulphurous oxide is obtained by combustion of sulphur or pyrites, the
best method being to connect the end of the pipe, flue, or chamber furthest from
the oven or furnace in which the sulphur or pyrites is burnt to a chimney or stack
so as to secure the necessary draft for the combustion of the sulphur and the
drawing of the sulphurous gas over the lime. The process is continued until the
sulphite at the end of the flue nearest the kiln has attained the necessary strength
or purity when it is withdrawn, and the lime brought forward from the rest of the
flue, fresh lime being substituted at the further end. The length or size of the
chambers or flue must be determined by the quantity of sulphurous gas to be
manufactured and passed through them, the object being that the gas shall be all
absorbed by the lime before it reaches the final escape pipe, from which little else
than steam and atmospheric air should pass away.
Fig. 1 is a sectional elevation of plant where the decomposition of sulphuric
acid and several chambers are used; Fig. 2, where a pyrites burner and one long
chamber is employed. The actual dimensions can vary at the option of the
manufacturer. If a short range of chamber be used more frequent stirrage and
changing of the calcic matters is required than when the chamber is very long.
Having now described my Invention, and the best modes known to me of
carrying it into effect, I wish it to be understood that what I specially believe to
be new, and desire to protect under the herein before in part recited Letters
Patent is,―

page_text: The manufacture or production of sulphite of lime by bringing sulphurous oxide
(SO) into actual contact with hydrate of lime, caustic lime, or any salt of calcium
in the dry or solid form decomposable by sulphurous oxide instead of by precipita-
tion from a liquid has heretofore practised.
In witness whereof, I, the said Richard Powell, have hereunto set my hand
and seal, this Tenth day of June, in the year of our Lord One thousand
eight hundred and eighty.
RICHARD POWELL. (L.S.)