Improvements in the Production of Solid Materials from Tar and other Substances.
Year: 1899

page_text: Date of Application, 24th June, 1899 --Accepted, 19th Aug., 1899
COMPLETE SPECIFICATION.
Improvements in the Production of Solid Materials from Tar
and other Substances.
I, CLEMENS DÖRR, of Germersheim, in the Empire of Germany, Official Surveyor,
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:—
The present invention relates to the production of solid materials having vary-
ing hardness from that of hard wood up to that of granite, by means of a hitherto
unknown capacity of tar to form a solid binding material, when it is mixed
under certain conditions with an excess of various filling materials. The use
of tar with or without the addition of resin and filling materials for the covering
of roofs and the like, which mixture hardens under the action of the air, is well-
known. But the use of the filling material in an excess for this purpose is
limited by the necessity that the mixture should be somewhat fluid when it is
applied. It is also known that the pitch-like residue from tar distillation with
or without the addition of bitumen, and mixture of chalk, gravel, or other finely
divided material, can be used as an artificial asphalt for paving and the like, or
can be cast in moulds so as to form blocks of various shapes. In this case the
binding material in its heated condition is already somewhat fluid and must be
sufficiently so in order that after the addition of the sand, gravel, or the like,
it may be still fluid enough to be poured into moulds or otherwise poured on to
the place where it is to be used. Pitch only contains the heavy oils of tar,
whilst the light oils and the medium oils have been driven off by distillation.
The present invention differs from both these methods not only in the process,
but also in its products. It is based on the following observations.
When tar is heated there are first formed whitish vapours; as the heating
is increased these vapours turn to grayish-blue, then to yellow, and then into
a more intense yellow with weak grayish tinges and lastly again to a grayish
colour. If this heating process is interrupted at any time during these various
stages and the remaining mass is tested after the loss of the distillation products
which have passed off in the aforesaid vapours, there will not be found any
appreciable difference between this mass and the original tar. It is sticky to
It is, indeed,
the finger, comes off to the touch and does not become solid.
altered in its chemical constitution, but externally the alteration is not easily
visible. If the same process is carried out with a mixture of tar and solid
granular or otherwise finely divided inorganic or organic bodies, for example sand
or sawdust, or a mixture of these materials, the vapours given off from the tar will
have the same appearance, and pass off in the same sequence. If a large quantity
of these filling materials, for example, at least three times the volume of sand
or gravel (that is to say, at least four times the weight of the tar) is used, and
the process is interrupted at the various stages it will be found that at a certain
period of the process a remarkable change takes place, the mass will first appear
as simply a mixture of a somewhat thick tar with the filling materials, and will
have more or less the qualities of ordinary tar, such as stickiness, etc. When
this mass is heated and if the heating process (and thus the distillation of the

page_text: volatile products in the tar) were interrupted at the various stages, the remaining
mass would still for some time show the properties of a thickened tar, but at
a certain period this appearance will alter, namely, when the temperature.of
the mixture has remained for some time at between 160 and 190° C., that is to
say also when the yellow vapours have ceased and the grayish vapours have
commenced to pass off. If the operation is interrupted at this stage the mass
will no longer appear as a fluid, or even as a viscid material, but will appear dry,
and of the consistency of mortar or cement. It no longer comes off to the touch,
nor attaches itself to the finger, but if pressed now between the fingers, it will
be found to be plastic. It is no longer fluid enough to be poured as would be
the mixture of pitch or asphalt with filling materials, but it can be made into
forms by placing it in moulds and pressing or stamping it. When these are
cold the material becomes a solid body which according to the nature of the
filling materials used in its appearance and qualities approaches more or less
to a natural stone, and no longer shows in any way the particular qualities of
a tarry mixture.
In order to produce such a product it is important to interrupt the heating
process when the temperature is between 160 and 190° C. The yellow vapours
must have passed into gray; at this period the mass appears as a dry mortar and
the process of boiling of the mass is complete, that is to say, at which the mass
has been fully boiled. If the process were carried further and, for example,
interrupted when the temperature of the mass had for some time exceeded 200° C.,
or if for some time gray vapours have been passing off, the mass will be over-
heated and the product will no longer be a coherent solid of the necessary nature,
but will be a friable mass which will be technically worthless. If, on the other
hand, the complete process of heating of the mass is not reached but the process
is interrupted too early, for example, below 150° C., the product when completely
cold will be still soft and remain unsuitable for the purpose for which it was
inteniled to be used. The most suitable temperature is between 160 and 190° C.,
but the temperature and the duration of the process might be extended so far
that the temperature exceeds 200° C., for a short time without being hurtful to
the product.
The chemical and mechanical aspects of the process are as follows:-During
the heating the ammonia water and the most volatile of the oils contained in
the tar especially benzol and toluol are first given off in the form of vapour
as the temperature rises. The less volatile of the light oils (xylol and its higher
homologues, such as phenol) are given off, the boiling point of which is below the
temperature in the retort. The oil vapours naturally take with them a small
amount of the more heavy bodies from the tar, specially phenols (cresol) and
hydrocarbons. On the other hand the hot tar will still contain small quantities
of the above mentioned lighter oils, whose boiling point is not very far below
the temperature of the retort. These small quantities are technically insignifi-
cant and do not effect the result of the process. It is important on the whole that
water, and the more volatile oils should be evaporated, whilst medium. oils also
those which by heating above the given temperature would be evaporated, should
be retained in the mixture. After the distillation is completed according to this
process the tar will have lost in all from 7 to 10 per cent. of its quantity. The
particles of the filling materials become coated with a thin layer of the binding
material, and by means of pressure they are firmly cemented together. The
binding material becomes solid in the cold and forms an insoluble cement for
the particles of the filling materials. If the medium oils are absent as in the
previous processes, this binding of the larger quantities of filling materials which
are present in this process will not take place.
In the practical working out of this process an open fire is not used for the
heating, as thereby a partial superheating of the mass would take place but steam
under pressure of a sufficient temperature is used for the heating. During the
process of heating the mass must be kept moving. The completion of the process,

page_text: that is to say, the completion of the heat action desired is indicated by observing
the colour of the vapours, or it may be found by taking a sample and seeing that
it has the desired properties. If the desired period is passed, even for a few
minutes the result will be that the product will quickly pass into that state in
which it is completely useless. When the heating process ceases the material
still in the hot state is placed in suitable moulds and pressed or stamped so
as to condense it therein. It can then be left to cool naturally, or be cooled
off by means of water. The finished product in its external appearance does not
appear very different whether sand or gravel, on the one hand, or sawdust on
the other, is used as a filling material, nor is there any appreciable difference
in appearance whether more or less of the filling materials are used. The pro-
portionate quantity of filling materials may be from three times to ten times
the quantity of the tar used. On the other hand, naturally the structure and
physical qualities of the product will offer some variation according to the amount
and nature of the filling materials, and these variations may be utilised in the
proportion of the product for various uses; if sharp sand or gravel, the product
resembles stone, almost of the hardness of granite, and it can be sculptured, cut,
or polished in a similar way to marble. If the addition of sand and gravel is
very large for example, such as eight to ten times the amount of the tar, this stone-
like material will become pervious to water. The product made with saw-dust
resembles ebony or vulcanite, and it may be used in place of these materials. By
the mixture of the filling materials, various products having properties inter-
mediate between those above mentioned will be formed. All these materials are
very resistant to acid, and in consequence of their elasticity and structural strength
they are very suitable for all kinds of technical purposes.
Instead of using raw tar, far can be previously prepared before the filling
materials are added to it by removing by distillation its watery constituents. The
distillate can be recovered in suitable condensing apparatus.
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 process of production of solid bodies having hardness between that of
wood and that of stone, consisting in the intimate mixture of granular or other-
wise finely divided inorganic materials, such as sand, gravel, or the like, or organic
materials such as, sawdust or the like, with from 10 to 30 per cent. of tar; heating
the same to from 150 to 200° C., or thereabouts, in order to remove from the tar
the more volatile of the constituents and subsequent pressing or stamping of the
mass before it is completely cold.
2. A solid material composed of a mixture of sand, gravel or similar finely
divided inorganic material with 10 to 30 per cent. of tar, boiled until the mass
appears as a dry mortar and subsequently pressed or stamped.
3. A solid material composed of a mixture of sawdust, or other finely divided
organic material with 10 to 30 per cent, of tar, boiled until the mass appears as
a dry mortar and subsequently pressed or stamped.
4. A solid material formed of a mixture of sand, gravel, or other inorganic
material with sawdust or other organic material, and 10 to 30 per cent. of tar
boiled until the mass appears as a dry mortar and subsequently pressed or
stamped.
T
T
1000
HERBERT HADDAN & Co.,
Agents to Applicant,
18, Buckingham Street, Strand, W.C., London.