Improved Process for Treating the Black Ash Residuum of Wood-pulp Manufacture.
Year: 1893

page_text: Improved Process for Treating the Black Ash Residuum of
Wood-pulp Manufacture.
I, LOUIS SIEGFRIED LANGVILLE of Room No. 60 Park Row, Times Building
in the City of New York and State of New York, United States of America,
Manufacturer, do hereby declare the nature of my invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
My invention relates to an improved process for producing the carbon product
described and claimed in Letters Patent of Great Britain No. 13,847, granted to
me the undersigned on July 29th, 1892, and the object and purpose of my improved
process is to benefit the material itself by the removal of foreign substances, and
by treatment to accelerate its preparation.
The carbon product described in my said Letters Patent is obtained from the
black-ash resulting as a residuum of wood-pulp manufacture, when the alkaline
treatment is used, and the following procedure is had :
Wood cut up into chips is placed in a digesting apparatus where under the
influence of steam pressure and heat it is treated with soda (made caustic as a
hydrate by lime) which dissolves from the wood cellulose the silica, converting it
into a silicate of soda, and saponifies the resins and gum resins, making them
soluble. After a treatment sufficient to accomplish these results the liquor is drawn
off from the wood cellulose, and contains some of the latter, the silicate of soda
obtained from the action of the caustic soda upon the silica contained in the
wood, and also the resinous substances that have been saponified by the caustic
alkali.
This liquor is then condensed by evaporation and transferred to a carbonizing
furnace wherein by the aid of heat, fire and the carbonic acid gas produced by the
latter, the soda hydrate is converted again into carbonate of soda, or as termed in
the art "recarbonized." After this is accomplished the carbonate of soda and
silica of soda are removed by bleaching, the residuum with water; the remaining
material consisting of the carbonized wood-cellulose, and carbonized resinous matter
and a trace of alkali, together with such foreign substances as have become mixed
with it during the several steps it has been passed through, such as sand,
firebrick, chips from the furnace linings, chips of iron from the machinery
cutting the wood into chips, and other substances incident to the handling of the
material.
To treat the black-ash residuum by my new process, it is mixed with water and
caused to flow through a trough with riffles in its bottom at right angles to the
trough, the carbon being lighter than such foreign substances as may have been
mixed with it, floats, while the impurities sink to be caught in the riffles. From
the trough the liquor runs into a tank where it is stirred, and treated with a weak
solution of acid, preferably hydrochloric acid, from this tank it runs to another
where it is washed by the aid of steam heat, and constant stirring. From this
latter tank it is run to settling tanks, where it is collected and the supernatant
liquid drawn off, from whence it goes to a dry room, when dried it is then finely
pulverized and packaged for market.
As thus treated all the impurities which become mixed with the black-ash while
in the converter, and during the recarbonizing process and which are denser than
the carbon, are removed, and the value of the product is materially increased.
While I have described my process as relating to the treatment of wood pulp
residuum, it may be used in the treatment of that resulting from the use of esparto
grass or other forms of wood cellulose.

page_text: The object of using au acid treatment to dissolve off the remaining alkali
facilitates the removal of the latter, although the same results may be accomplished
by repeated washings aided by heat.
The residuum thus treated is well adapted for making electric light carbons,
india ink for drawing purposes, as an ingredient for writing ink, gun-powder, paint
and other uses where carbon is employed.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
The process herein described for treating black ash residuum consisting in
running it mixed with water through a trough containing riffles in its bottom, and
into a tank; then treating it to remove the remaining trace of alkali by repeated
washing and agitation and by acid, then conveying it into tanks to settle, to be
followed by drawing from off it the supernatant liquor; then conveying it to a
drying room, and when dried, pulverizing it, as and for the purposes herein set
forth.
Dated this 20th day of & nril 1802
LOUIS SIEGFRIED LANGVILLE.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.