IMPROVEMENTS IN BLEACHING CHINA CLAYS OR PORCELAIN CLAYS AND THE REMOVAL OF THE COLOURING MATTER CONTAINED THEREIN, ALSO FOR AN IMPROVED APPARATUS FOR MAKING THE SUL- PHUROUS ACID USED IN CONNEXION THEREWITH
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by John Carr at the Office of the Com-
missioners of Patents on the 10th January 1877.
JOHN CARR, of No. 42, Loudoun Square, Cardiff, in the County of Glamorgan,
China Clay Proprietor and Merchant. "IMPROVEMENTS IN BLEACHING CHINA
CLAYS OR PORCELAIN CLAYS AND THE REMOVAL OF THE COLOURING MATTER
CONTAINED THEREIN, ALSO FOR AN IMPROVED APPARATUS FOR MAKING THE SUL-
PHUROUS ACID USED IN CONNEXION THEREWITH."
My Invention relates to a method or process for bleaching clays used in the
manufacture of porcelain; paper, and for other chemical and manufacturing purposes.
In order to remove the organic or colouring matter the said clays contain in
their natural state, at a certain stage in the process of their preparation or
manufacture, and whilst the clays are in a liquid or running state, treat them
(the clays) by adding thereto a chemical composition composed nearly as follows,
viz:-Chlorine gas, by parts, 100; hydrochloric acid, by parts, 100 to 200 parts;
water and clay combined, 100 parts; sulphurous acid gas and water to 300 parts,
water and clay combined; sulphuric acid, 100 parts to 400 parts, water and clay
combined; hyposulphite of soda, bi-sulphite of soda, and hypochlorite of soda, these
are all used in combination with the four before-mentioned chemicals according as
the various qualities of clay require; oxalic acid, by parts, 100%; to water and clay
combined 150 parts. The action of all these chemicals on the clay is to effect the
process of bleaching without breaking up the component parts of the china clay.
The bleaching action commences within sixty minutes after application, but the
longer the acid is allowed to remain in the clay tank mixed with the clay the more
effectual and economical is the process, as china clays vary very much as to the
quantity of organic matter originally contained in them. Another advantage of
this process is, that when acids are used without the gas, the solution may be
worked over again by conveying it back over the clay stopes, thereby reducing the
original quantity required for the purpose of bleaching. When, by means of the
action of the chemical before mentioned, the process of bleaching has been completed,
the clay is then dried in a kiln as usual.
My improved apparatus for producing the sulphurous acid gas required in this
Invention, consists of an erection constructed of fire-bricks and clay, measuring
about 6 feet in length, 6 feet in height, and 3 feet in width, divided into 3 com-
partments or chambers, and numbered 1-2-3.

page_text: Compartment No. 1 is about 2 feet high, 1 foot 6 inches wide, has a semi-arched
roof; in this arched roof I place sulphur and sulphuric acid, which are ignited
and kept constantly burning either by means of air supplied through a suction pipe
inserted within 9 inches of the top of the chamber No. 3, or by a fire lighted under-
neath the slab on which are placed the sulphur and sulphuric acid above named;
chamber is also provided with an aperture through which the gas escapes and passes
into chambers 2 and 3.
this
Chamber No. 2 is about 3 feet by 1 foot 2 inches, is filled with clean gas coke,
and at its extreme end there is fixed a 4 inch earthen pipe, about 1 foot long, to
which is attached a leaden pipe of corresponding diameter and sufficiently long to
convey the gas water to the clay as it runs through glazed earthen pipes, or covered
launders, from the micus the settling pits.
.
Chamber No. 3 is about 5 feet high, 1 foot 2 inches square, having a small
aperture at the top in which is placed a pipe of inch bore. This pipe conveys
a constant stream of water into this chamber, which is also filled with clean gas
coke like unto chamber 2, the water passing down through the before-mentioned
coke becomes impregnated with the generated sulphurous gas passing out through
the pipe inserted at the end of chamber 2. Within 9 inches of the top is a suction
pipe, 3 inches in diameter, referred to in my description of chamber 1, and is carried
out to the nearest stream of water to keep up the ignition of chamber 1, and thus
dispense with the use of a fire; but the apparatus is provided with a suitable fire-
place and ash pit for use when no stream of water is near at hand for feeding this
suction pipe.