Improvements in the Manufacture of Filtering Materials.
Year: 1899

page_text: Date of Application, 27th Dec., 1899-Accepted, 10th Feb., 1900
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Filtering Materials.
I, EDWARD POHL, of 115, Hohenberg, Kalk, near Cologne, in the German
Empire, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement, that is to say:-
This invention has for its object to improve the filtering quality of wood char-
coal, animal charcoal, blood charcoal, and bone charcoal, kieselguhr, asbestos, and
other like materials.
The action of the filtering material depends on the state or condition of the
pores, ducts, or channels existing it. In case these pores are large and their
walls smooth, the fine bodies suspended in the liquid to be filtered will not be
effectively removed. If, however, the walls of the pores be covered with a
porous coating, and if porous substances reduced to fine powder be allowed to
deposit in them, the filtering material will be considerably improved since by
this means the smallest particles suspended in the liquid will be retained by the
porcus coating, or by the porous substances filling up the pores.
Experiments have proved that the most suitable coating or filling is obtained
by decomposing hydro-carbons at a glowing heat so as to separate the pure
carbon from them.
This carbon is distributed in the pores and upon their walls, either by intimately
mixing the filtering material reduced to a granular condition with the previously
produced carbon, or preferably by producing the said carbon as a very fine
powder inside the filtering material and causing the same to deposit in the pores.
The invention can be carried out, for example, in the two following ways, it
being assumed that charcoal is the filtering medium employed:
1. By first producing carbon separately, by treating carbon containing. sub-
stances at a glowing heat (hydrocarbons being most suitable for the purpose)
and then reducing such carbon to a fine powder and intimately mixing the same
with the charcoal previously reduced to small pieces, in such a manner that the
carbon may be disseminated in a practically molecular state throughout the
charcoal.
2. By raising the charcoal to a glowing heat in a space from which air is
excluded, and in the presence of gases which, when subjected to a glowing heat,
are capable of undergoing decomposition, the carbon separating from its com-
pound in the form of a very fine powder.
For this purpose the gaseous and the liquid hydrocarbons are most suitable.
If a gaseous hydrocarbon be employed it is advisable to first create a vacuum
in the apparatus wherein the process is to take place, and then to admit the
hydrocarbon after the charcoal has been brought to a glowing heat.
The fine carbon particles deposit in the pores and interstices of the glowing
charcoal and will divide the small intermediate cells or cavities into still smaller
ones having porous walls, so that the filtering action will be considerably in-
creased owing to the charcoal being treated as above described.
Instead of employing charcoal alone, other effective filtering materials, such

page_text: as kieselguhr, asbestos, and the like, may be mixed with it, and the mixture be
then treated in the manner set forth.
The invention can also be carried out by making use of heavy liquid hydro-
carbons, as for example oil, petroleum, shale oil, tar, or like substances which
also part with their carbon when raised to a glowing heat. In this case, the
filtering materials, reduced to small pieces, are intimately mixed with the said
liquid hydrocarbons and the mixture is subjected to a glowing heat without
admission of air. The liquids are then decomposed by the heat and their
residues in the pores of the material appreciably increase the filtering quality,
and furthermore render the filtering medium much denser.
The invention may be applied with great advantage to improving the action of
those filtering charcoals which have hitherto been considered the best of their
kind, that is to say animal charcoal, blood charcoal and bone charcoal. These
charcoals are advantageously treated according to Example 2, being brought to a
glowing heat in the presence of hydrocarbons without admission of air.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. An improved filtering charcoal consisting of an intimate mixture of ordinary
filtering material, such as wood charcoal, animal charcoal, blood charcoal, kiesel-
guhr, asbestos, and the like, with solid carbon this latter being produced by
decomposing hydrocarbons at a glowing heat.
2. The product obtained by mixing the filtering material or materials, reduced
to a granular condition, with carbon produced by subjecting hydrocarbons to a
glowing heat.
3. The product obtained by subjecting the filtering material to a glowing
heat, without admission of air, in the presence of gases which when exposed to
such a heat are decomposed and deposit their carbon.
4. In the treatment referred to in Claim 3, forming a vacuum in the apparatus
wherein the charcoal is subjected to a glowing heat before the hydro carbon is
admitted.
5. The modification in which the filtering material is brought to a glowing
heat together with heavy liquid hydrocarbons such as oil, petroleum, shale oil,
tar, or the like.
6. My improvements in the manufacture of filtering materials by the incor-
poration with a filtering medium, such as before mentioned, of carbon produced
by the decomposition of a hydrocarbon under the action of heat, substantially
as described
Dated this 7th day of December 1899.
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 5A, Market Street, Nottingham,
Agent for the Applicant.