Improvements in the Manufacture and Treatment of Filtering and Decolorizing Materials.
Year: 1899

page_text: Date of Application, 3rd Jan., 1899
Complete Specification Leít, 28th Mar., 1899-Accepted, 29th Apr., 1899
[Communicated from abroad by CHARLES CATLETT, of Staunton, in the County
of Augusta and State of Virginia U.S.A., Inventor.]
Improvements in the Manufacture and Treatment of Filtering and
Decolorizing Materials.
I, REGINALD WALTER BARKER, of 56, Ludgate Hill, in the County of London,
Patent Agent, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the manufacture and treatment of
filtering and decolorizing materials and in means for increasing the duration and
efficiency of the same. The objects of this invention are to provide a material
which can be used as a substitute for animal charcoal, fuller's earth or other like
substances commonly used for filtering and decolorizing purposes and also a
method of treating said filtering and decolorizing materials in such a way as to
increase the duration and efficiency of the same.
It is well known that the value of bone charcoal or other filtering and
decolorizing medium, is due to the large amount of carbon surface exposed, and
I have discovered that an efficient substitute can be made by using clay as a base
and covering the surface of its pores with a layer of carbon, preferably in an
attenuated condition. By this means an extended surface of active carbon is
produced without substantially closing the pores, and thus I obtain a material
which although cheaper is superior to bone charcoal in that from its plastic
nature at certain stages of its manufacture it may be moulded into discs, tubes, or
any other desirable forms, and it can be revivified and in all other respects treated
and used in the same manner and for the same purposes as bone charcoal, while
by proper selection of clays it may be used as a filtering medium for substances
for which bone charcoal on account of its composition is not suitable.
I find also that the best mode of producing this result is to treat the clay with
the carbonaceous material in the form of a dilute solution, the solvent being water
or other liquid, depending upon the character of the material. Such dilute
solution is desirable in order the better to cover the pores with an attenuated
layer of carbon with the least obstruction to the passage of the liquid through
the pores when the material is used for filtering. Importaut results are obtained
by using such proportion of carbonaceous material as to leave in the clay, after
the same has been charred, from 4 to 8 per cent. of carbon, though the pro-
portion may be lessened within the scope of uy invention, but in no case should
the proportion of residual carbon exceed 8/3 per cent. of the mass.
It being desirable to use the material in a granulated form, I have discovered
that by sizing the clay after treating it with carbonaceous solution and before
charring the product of dust, due to the crushing and sizing, is reduced to a
minimum, and that, further, the dust which may be formed is not lost but may
he incorporated in a new portion of unsized material.

page_text: I have discovered also that certain natural clays contain the proper amount of
carbonaceous material so disseminated as to form when charred, the desired thin
coating of carbon over the surface of the pores, and also that it is possible in
those clays containing carbonaceous material in proportions insufficient to form
such coating to add more carbonaceous material in dilute solution to produce
the desired effect.
In describing the method for carrying my invention into practice, it is assumed
that those skilled in the art may, within the limits of my claims. vary the same
in respect of the nature of the materials and the manner of their treatment.
Different clays will of course require somewhat different manipulation, but the
necessity for such variations will be readily apparent to anyone understanding
the principle of my invention.
Taking the necessary quantity of clay (an ordinary residual or limestone clay
for example) I add a solution of a low grade sugar or syrup, containing such
proportion of sugar that its solid contents would represent about 14% and not
more than 25% of the weight of the clay, and mix the two thoroughly together.
The volume of the solution is such as to saturate the clay fully. The clay in
then dried until it becomes tough and can be readily crushed and granulated, and
after being crushed it is sized by suitable screens. The material which is too
large is recrushed and that which is too small is mixed with a fresh lot. The
sized material is then charred in a closed retort with the exclusion of air at a
temperature which, while high enough to bake the clay, is not so high as to
cause fusion of the clay and the closing of the pores. In treating limestone clav,
which is readily fusible, the temperature should not exceed a low red heat. It
is then cooled with exclusion of air, preferably washed and dried and is ready
for use.
The material thus made is black or grayish in color, the carbon is
uniformly spread over the surface of the pores as a thin coating and that the
porosity of the material has not been impaired is evidenced by the readiness with
which it absorbs liquids. Like a good bone charcoal it adheres with great readi-
ness to the tongue. The proportion of syrup above noted will afford the requisite
amount of carbon in the finished product.
Instead of syrup or sugar, other forms of carbonaceous matter, and liquid
solvents other than water, may be used. For example I may employ aqueous
solutions of starch, glucose, glue, or solutions of coal tar. cotton seed oil and
other vegetable oils or petroleum and its products, in suitable_solvents
In using natural carbonaceous, clays, I may take for example a clay found
near Stuart's Draft on the Shenandoah Valley Branch of the Norfolk and
Western R.R. in Virginia U.S.A. containing the requisite small proportion of
carbonaceous matter and which yields the proper amount of carbon coating in
the pores of the finished product. Many other similar carbonaceous clays
are to be found in various portions of the United States. Such clay is
moistened with water mixed to a uniform consistency. is dried, crushed, sized
and charred as above stated. This clay being very refractory can be charred at
a relatively high temperature without injury.
Good results can be produced by treating a clay, which has already been baked
at a temperature not high enough to cause a closing of its pores, with a dilute
solution of carbonaceous material containing sufficient carbonaceous material to
provide the requisite amount of carbon and so diluted as to saturate said clay
(and thus uniformly spread the carbon over the pores) then drving and charring
in closed retorts. In this mode of practicing the invention, the clay, while pre-
ferably sized before baking, may either be crushed and sized after baking and
before treating with the solution of carbonaceous material, or it may be crushed
and sized after treating with the carbonaceous solution and before charring, or
it may he crushed and sized after charring.
In treating raw clay with an aqueous solution it becomes soft and plastic and
may be molded, and on drving it becomes hard (becoming soft again, however, on
the addition, of water) and may be crushed and sized. Clay does not however,

page_text: .
become soft on the addition of most of the other solvents, though it absorbs them
readily, nor does it become hard when they are driven off. Therefore, when
using such solvents, the clay should be moistened with water and moulded, or
dried and sized before adding the solution of carbonaceous material, when other
solvent than water is employed. The solvent is then recovered, and the material
charred. In a similar manner carbonaceous material requiring solvents other
than water may be applied to the baked clay.
Instead of granulating the product it may be molded into filters in the form
of disks, tubes or vessels.
Having recognised the fact that the life of materials used for filtering and
decolorizing purposes, whether composed of ordinary bone charcoal, fullers
earth, clays or other similar materials as herein described when treated by the
well known system of revivification, is limited largely by the accumulation in
the pores of the material of an excess of carbon, and that more carbon is often
contained in the new material than is desirable for most efficient work, I have
discovered that the excess of-carbon can be removed to a greater or less extent by
reheating the said materials, after being revivified or freshly manufactured as
the case may be, in closed retorts or ordinary revivifying kilns into which
provision is made to prevent the admission of air.
If after reheating, the material is cooled by methods common in the ordinary
processes of manufacture and revivification and again heated, a second portion
of carbon is removed, and thus by excessive reheatings, if one is not sufficient,
the amount of carbon can be reduced to any point desired. I have also discovered
that this destruction of more or less carbon is largely due to the oxygen which
said material when new or revivified has the power of condensing in its pores,
and that therefore the destruction of carbon takes place in all parts of the material.
Such exposure of the material to the air as occurs in ordinary handling being
sufficient to insure absorption of oxygen.
Furthermore I have discovered that the amount of oxidation is a function of the
time and temperature of heating and may be modified within the scope of my
invention, and as will be plain to those familiar with the art, by such modifica-
tions the amount of carbon removed can be greatly varied, while the removal of
the excess of carbon commences to take place at a very low temperature, and any
temperature may be used short of injury to the framework or structure of the
material. Thus in a sugar refinery, after testing to see approximately the
amount of carbon destroyed under the ordinary working of the kiln by one
passage of new or revivified charcoal through it, it is only necessary, when
the excess of carbon as shewn by analysis has reached this amount to pass the
material after revivification and cooling in the usual way a second time through
the kiln, when the amount of carbon will be found reduced to approximately the
first figure.
As an example: Suppose that the material contained 9% of carbon originally.
and it having been shown by experiment that the amount of carbon destroyed
by passing the said material a single time through the kiln as worked at this
refinery amounted to 75% and suppose that on the 25th revivification the total
carbon was found to have been increased to 9.75% it would only be necessary to
pass the revivified material a second time through the kiln heated and worked in
the usual way when the carbon would be again reduced to approximately the
original figure.

page_text: Improvements in the Manufacture and Treatment of Filtering and
Decolorizing Materials.
I, REGINALD WALTER BARKER, of 56, Ludgate Hill, in the County of London,
Patent Agent, 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:-
This invention relates to improvements in the manufacture and treatment of 5
filtering and decolorizing materials and in means for increasing the duration and
efficiency of the same. The objects of this invention are to provide a material
which can be used as a substitute for animal charcoal, Fuller's earth or other like
substances commonly used for filtering & decolorizing purposes and also a
method of treating said filtering and decolorizing materials in such a way as to 1
increase the duration and efficiency of the same.
It is well known that the value of bone charcoal or other filtering and
decolorizing medium is due to the large amount of carbon surface exposed and
I have discovered that an efficient substitute can be made by using clay as a base
and covering the surface of its pores with a layer of carbon preferably in an 1
attenuated condition. By this means an extended surface of active carbon is
produced without substantially closing the pores, and thus I obtain a material
which although cheaper is superior to bone charcoal in that from its plastic
nature at certain stages of its manufacture it may be moulded into discs, tubes, or
any other desirable forms and it can be revivified and in all other respects treated 2
and used in the same manner and for the same purposes as bone charcoal, while
by proper selection of clays it may be used as a filtering medium for substances
for which bone charcoal on account of its composition is not suitable.
I find also that the best mode of producing this result is to treat the clay with
the carbonaceous material in the form of a dilute solution, the solvent being water
or other liquid, depending upon the character of the material. Such dilute
solution is desirable in order the better to cover the pores with an attenuated
layer of carbon with the least obstruction to the passage of the liquid through
the pores when the material is used for filtering. Important results are obtained
by using such proportion of carbonaceous material as to leave in the clay after 3
the same has been charred, from 4 to 8 per cent. of carbon though the pro-
portion may be lessened within the scope of my invention but in no case should
the proportion of residual carbon exceed 8 per cent. of the mass.
It being desirable to use the material in a granulated form I have discovered
that by sizing the clay after treating it with carbonaceous solution and before
charring the product of dust, due to the crushing and sizing, is reduced to a
minimum, and that, further the dust which may be formed is not lost but may
be incorporated in a new portion of unsized material.
I have discovered also that certain natural clays contain the proper amount of
carbonaceous material so disseminated as to form when charred the desired thin
coating of carbon over the surface of the pores, and also that it is possible in
those clays containing carbonaceous material in proportions insufficient to form
such coating to add more carbonaceous material in dilute solution to produce
the desired effect.
In describing the method for carrying my invention into practice, it is assumed
that those skilled in the art may, within the limits of my claims, vary the same
in respect of the nature of the materials and the manner of their treatment.
Different clays will of course require somewhat different manipulation, but the

page_text: necessity for such variations will be readily apparent to anyone understanding
the principle of my invention.
Taking the necessary quantity of clay (an ordinary residual or limestone clay
for example) I add a solution of a low grade sugar or syrup containing such
proportion of sugar that its solid contents would represent about 14% and not
more than 25% of the weight of the clay, and, mix the two thoroughly together.
The volume of the solution is such as to saturate the clay fully. The clay is
then dried until it becomes tough and can be readily crushed and granulated, and
after being crushed it is sized by suitable screens. The material which is too
large is recrushed and that which is too small is mixed with a fresh lot. The
sized material is then charred in a closed retort with the exclusion of air at a
temperature which while high enough to bake the clay, is not so high as to
cause fusion of the clay and the closing of the pores. In treating limestone clay,
which is readily fusible, the temperature should not exceed a low red heat. It
is then cooled with exclusion of air, preferably washed and dried and is ready
for use.
The material thus made is black or grayish in color, the carbon is
uniformly spread over the surface of the pores as a thin coating and that the
porosity of the material has not been impaired is evidenced by the readiness with
which it absorbs liquids. Like a good bone charcoal it adheres with great readi-
ness to the tongue. The proportion of syrup above noted will afford the requisite
amount of carbon in the finished product.
Instead of syrup or sugar other forms of carbonaceous matter, and liquid
solvents other than water, may be used. For example I may employ aqueous
solutions of starch, glucose, glue, or solutions of coal tar, cotton seed oil and
other vegetable oils or petroleum and its products in suitable solvents.
.
In using natural carbonaceous clays, I may take for example a clay found
near Stuart's Draft on the Shenandoah Valley Branch of the Norfolk &
Western R.R. in Virginia, U.S.A. containing the requisite small proportion of
carbonaceous matter and which yields the proper amount of carbon coating in
the pores of the finished product. Many other similar carbonaceous cluys
are to be found in various portions of the United States. Such clay is
moistened with water mixed to a uniform consistency, is dried, crushed, sized
and charred as 'above stated. This clay being very refractory can be charred at
a relatively high temperature without injury.
Good results can be produced by treating a clay, which has already been baked
at a temperature not high enough to cause a closing of its pores, with a dilute
solution of carbonaceous material containing sufficient carbonaceous material to
provide the requisite amount of carbon and so diluted as to saturate said clay
(and thus uniformly spread the carbon over the pores), then drying & charring
in closed retorts. In this mode of practising the invention, the clay, while pre-
ferably sized before baking, may either be crushed and sized after baking and
before treating with the solution of carbonaceous material, or it may be crushed
and sized after treating with the carbonaceous solution and before charring, or
it may be crushed and sized after charring.
In treating raw clay with an aqueous solution it becomes soft and plastic and
may be molded, and on drying it becomes hard (becoming soft again, however, on
the addition, of water) and may be crushed and sized. Clay does not, however,
become soft on the addition of most of the other solvents, though it absorbs them
readily, nor does it become hard when they are driven off. Therefore, when
using such solvents, the clay should be moistened with water and molded, or
dried and sized before adding the solution of carbonaceous material, when other
solvent than water is employed. The solvent is then recovered, and the material
charred. In a similar manner carbonaceous material requiring solvents other
than water may be applied to the baked clay.
Instead of granulating the product it may be molded into filters in the form
of disks, tubes or vessels.
Having recognised the fact that the life of materials used for filtering and

page_text: decolorizing purposes, whether composed of ordinary bone charcoal, Fullers
earth, clays or other similar materials as herein described when treated by the
well known system of revivification, is limited largely by the accumulation in
the pores of the material of an excess of carbon, and that more carbon is often
contained in the new material than is desirable for most efficient work. I have
discovered that the excess of carbon can be removed to a greater or less extent by
reheating the said materials, after being revivified or freshly manufactured as
the case may be, in closed retorts or ordinary revivifying kilus into which
provision is made to prevent the admission of air.
If after reheating, the material is cooled by methods common in the ordinary
processes of manufacture and revivification and again heated, a second portion
of carbon is removed, and thus by successive reheatings, if one is not sufficient
the amount of carbon can be reduced to any point desired. I have also discovered
that this destruction of more or less carbon is largely due to the oxygen which
said material when new or revivified has the power of condensing in its pores,
and that therefore the destruction of carbon takes place in all parts of the material.
Such exposure of the material to the air as occurs in ordinary handling being
sufficient to insure absorption of oxygen.
Furthermore I have discovered that the amount of oxidation is a function of the
time and temperature of heating and may be modified within the scope of my
invention, and as will be plain to those familiar with the art, by such modificu
tious the amount of carbon removed can be greatly varied, while the removal of
the excess of carbon commences to take place at a very low temperature, and any
temperature may be used short of injury to the framework or structure of the
material. Thus in a sugar refinery after testing to see approximately the
amount of carbon destroyed under the ordinary working of the kiln by one
passage of new or revivified charcoal through it, it is only necessary, when
the excess of carbon as shewn by analysis has reached this amount to pass the
material after revivification and cooling in the usual way a second time through
the kiln, when the amount of carbon will be found reduced to approximately the
first figure.
As an example:-Suppose that the material contained 9% of carbon originally
and it having been shown by experiment that the amount of carbon destroyed
by passing the said material a second time through the kiln as worked at this
refinery amounted to 75% and suppose that on the 25th revivification the total
carbon was found to have been increased to 9-75% it would only be necessary to
pass the revivified material a second time through the kiln heated and worked in
the usual way when the carbon would be again reduced to approximately the
original figure.
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). The method of treating clay to obtain a filtering or decolorizing material
consisting of covering the surfaces of its porcs with a thin layer of carbonaceous
matter, or of dilute liquid carbonaceous matter not greater in proportion when
charred than 8 per cent. of the mass, and drying fracturing, sizing and then
baking the same in a closed vessel at a temperature below its fusing point sub-
stantially as and for the purpose herein set forth and described.
(2) The method of making filtering or decolorizing material of clay charged
with carbonaceous liquid, which consists of drying, fracturing and sizing the
same before charring, substantially as and for the purpose herein set forth and
described.
(3) The method of making filtering or decolorizing material which consists of
treating clay with carbonaceous liquid, then drying fracturing and sizing the

page_text: same, and then charring, substantially as and for the purpose herein set forth
and described.
(4) A composition of matter for filtering or decolorizing, consisting of baked
clay having open pores whose walls are conted with charred carbon not greater
when charred than 8 per cent. of the mass substantially as and for the purpose
herein set forth and described.
(5) A composition of matter for filtering and decolorizing consisting of clay
having open pores whose walls are coated with carbon in the form of an attenuated
film, in proportion when charred of from 4 to 8 per cent. of the mass, substanti-
ally as and for the purpose herein set forth and described.
(6) Molded filters in the form of disks tubes or vessels, composed of clay whose
pores have a charred carbon coating, said carbon being present in proportion
when charred of from 4 to 8 per cent. of the mass substantially as and for the
purpose herein set forth and described.
(7) The method of preparing and revivifying spent filtering material, which
consists of charring the same, cooling and exposing it to air and subsequently
reducing the carbon contents of the material by reheating the same in a retort
closed to prevent the admission of air whereby a portion of the carbon is con-
aumed by action of the oxygen contained within the pores of the material,
substantially as and for the purpose lierein set forth and described.
Dated this 28th day of March 1899.