IMPROVEMENTS IN THE MANUFACTURE OF SULPHITES AND BISULPHITES FOR BLEACHING PURPOSES
Year: 1882

page_text: LETTERS PATENT to John Imray of No 28 Southampton Buildings Chancery
Lane in the County of Middlesex for an Invention of IMPROVEMENTS
IN THE MANUFACTURE OF SULPHITES AND BISULPHITES FOR BLEACHING
PURPOSES
to him from abroad by Fabien Charles
Communicated
PROVISIONAL SPECIFICATION left by the said John Imray at the Office
of the Commissioners of Patents on the 8th August 1882.
JOHN IMRAY of No. 28 Southampton Buildings Chancery Lane in the County of
Middlesex Et IMPROVEMENTS IN THE MANUFACTURE OF SULPHITES AND BISULPHITES
FOR BLEACHING PURPOSES [Communicated to him from abroad by Fabien
Charles Kudelski of La Vendée in the Republic of France]
"
This invention relates to a process for transforming sulphates of soda, potassa,
magnesia or ammonia into. sulphites or bisulphites suitable for bleaching materials
for pulp or textile purposes. In a vessel provided with an agitator a current of
sulphurous acid is passed through a milk of lime or carbonate of lime, and when
the solution is concentrated to about 8° or 9° Beaumé the sulphate to be treated
is added. When the solution is sufficiently sulphited, the current of sulphurous
acid is stopped, the vessel is emptied and after the contents have settled, the clear
liquor is decanted off. Residuary soluble sulphates and sulphites can be separated
by washing The liquor produced as above described can be applied for bleaching
in the usual way in lead lined vessels heated by steam. The sulphites employed
for bleaching become more or less converted into sulphates or bisulphates.
These may be calcined and reconverted as above described into sulphites or
bisulphites.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Imray in the Great Seal Patent Office on the 7th February
1883.
JOHN IMRAY of N° 28 Southampton Buildings Chancery Lane in the County of
Middlesex "IMPROVEMENTS IN THE MANUFACTURE OF SULPHITES AND BISULPHITES
FOR BLEACHING PURPOSES " A communication to me from Abroad by Fabien
Charles Kudelski of La Vendée in the Republic of France
This invention relates to a process for transforming sulphates of soda, potassa,
magnesia, or ammonia into sulphites or bisulphites suitable for bleaching materials
for pulp or textile purposes. In a vessel provided with an agitator a current of
sulphurous acid is passed through a milk of lime or carbonate of lime, and when
the solution is concentrated to about 8° or 9° Beaumé the sulphate, to be treated is
added. When the solution is sufficiently sulphited, the current of sulphurous acid
is stopped, the vessel is emptied and after the contents have settled, the clear
liquor is decanted off. Residuary soluble sulphates and sulphites can be
separated by washing. The liquor produced as above described can be applied for
bleaching in the usual way in lead lined vessels heated by steam. The sulphites
employed for bleaching become more or less converted into sulphates or bisulphates.
These may be calcined and reconverted as above described into sulphites or
bisulphites.
The apparatus employed for the treatment above described may be variously
arranged; the accompanying drawing shews a convenient arrangement for the
purpose. Fig. 1 is a longitudinal section shewing a number of vessels each pro-
vided with a revolving agitator, and connected with the next by a bent leaden
pipe P above and a straight pipe Q a little below the level of the liquid contents.
These vessels are charged with the solution of the sulphate and the lime or
carbonate of lime; its supply is kept up to the last vessel through a pipe B, and
the converted liquid being a solution of bisulphite flows out from the first vessel
by the pipe C, while the sulphurous acid gas enters the first vessel by the pipe A
and passes from vessel to vessel by the pipes P in a direction opposite to that in
which the solution passes. The solution of bisulphite issuing by the pipe C is
particularly available in the treatment of wood for the production of pulp. A con-
venient apparatus for this purpose is arranged as follows. The wood to be treated
is cut in oblique slices by a machine such as is shewn in section at Fig. 2 and in
elevation at Fig. 3 where D is a revolving disc carrying cutters E that slice the
wood fed through the tube A. The slices are treated in a vessel F such as is shewn
mostly in section at Fig 4, which vessel is mounted on trunnions and caused to
revolve by worm or other suitable gearing. This vessel is slightly tapered and
lined with lead, one end of it being secured by flanges H which can be disconnected
to give access for repairing the lining. In the removeable end of the vessel is fixed
a pipe coil J which is supplied with steam for heating through one of the trunnions,
the water of condensation passing away by the other trunnion G. At the other
end of the vessel is a manhole K provided with a cover L for charging and dis-
charging. The vessel being charged with the wood slices and with bisulphite, such
as the bisulphite of soda of a strength of 6° to 8° Beaumé, the contents are heated
by the steam admitted to the coil J and are kept in agitation by the revolution of
the vessel. The pressure and time of treatment vary with the character of the
material; usually the pressure within the vessel is from 3 to 5 atmospheres and
the time from 8 to 16 hours, the completion of the process being ascertained by the
peculiar smell of the escaping gases.

page_text: Having thus described the nature of this invention and in what manner the
same is to be performed as communicated to me by my foreign correspondent, I
claim :-
The herein described process for transforming alkaline sulphates into sulphites or
bisulphites suitable for bleaching.
In Witness whereof I the said John Imray have hereunto set my hand and
seal this seventh day of February in the year of our Lord One thousand
eight hundred and eighty-three.
JOHN IMRAY (L.S.)