IMPROVEMENTS IN UTILISING SULPHURIC ACID TAR
Year: 1876

page_text: LETTERS PATENT to John Calderwood, of Addiewell Chemical Works, in
the County of Mid Lothian, North Britain, Manager of the said Works, for
the Invention of "IMPROVEMENTS IN UTILISING SULPHURIC ACID TAR."
Sealed the 15th December 1876, and dated the 4th July 1876.
PROVISIONAL SPECIFICATION left by the said John Calderwood at the
Office of the Commissioners of Patents on the 4th July 1876.
JOHN CALDERWOOD, of Addiewell Chemical Works, in the County of Mid Lothian,
North Britain, Manager of the said Works. "IMPROVEMENTS IN UTILISING
SULPHURIC ACID TAR."
This Invention relates to utilising the acid tar obtained when paraffin, petroleum,
and other oils are refined by means of sulphuric acid.
In the process of refining mineral and other oils the sulphuric acid employed,
acting on certain tarry substances present therein, gives rise to the well known
viscid liquid commonly called acid or vitriol tar. The present Invention consists
in the application of this tar to the production of alum, sulphate of alumina, and
sulphate of iron, from shale residue (black stuff), china, fire, or other clays, or
other alumina yielding substances.
The tar may either be employed in the state in which it comes from the oil
refining processes, or by preference it is agitated with hot water, or a current of
steam is led into it so as to separate from the bulk of the tar a weak impure acid.
This acid having been concentrated to the point best adapted for decomposing the
particular aluminous material employed, is mixed with the proper proportion of
such material previously calcined and ground, the mixture being maintained at the
temperature most suitable for the formation of the sulphates. The mixture having
been allowed to remain in a covered place for some days is then transferred to a
reverberatory, muffle, or equivalent furnace, and there heated until the tarry
substances associated with the sulphuric acid have been carbonized. The mass is
then lixiviated, and from the solution sulphate of alumina and sulphate of iron, or
(with the addition of sulphate of ammonia or sulphate of potash) alum are
prepared by the ordinary processes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Calderwood in the Great Seal Patent Office on the 1st January
1877.
"..
JOHN CALDERWOOD, of Addiewell Chemical Works, in the County of Mid Lothian,
North Britain,Manager of the said Works. "IMPROVEMENTS IN UTILISING
SULPHURIC ACID TAR."
My said Invention relates to utilising the acid tar obtained when paraffin,
petroleum, and other oils are refined by means of sulphuric acid.
In the process of refining mineral and other oils the sulphuric acid employed
acting on tarry substances present therein, gives rise to the well-known viscid
liquid commonly called acid or vitrol tar. The present Invention consists in the
application of this tar to the production of aluın, sulphate of alumina, and sulphate
of iron from shale residue (black stuff), china, fire, or other clays, or other alumina
yielding substances.
The tar may either be employed in the state in which it comes from the oil
refining processes, or by preference it is agitated with water, or a current of steam
is led into it so as to separate from the bulk of the tar a weak impure acid. This
acid, having been concentrated to the point best adapted for decomposing the
particular aluminous material employed, is mixed with such material previously
calcined and ground, the mixture being maintained at the temperature most
suitable for the formation of the sulphates. The mixture having been allowed to
remain in a covered place for some days is then transferred to a reverberatory,
muffle, or equivalent furnace, and there heated until the tarry substances associated
with the sulphuric acid have been carbonized. The mass is then lixiviated, and
from the solution sulphate of alumina and sulphate of iron, or (with the addition
of sulphate of ammonia or sulphate of potash) alum, are prepared by the ordinary
processes.
When shale residue or other material containing iron as well as alumina is
employed the mass formed by the action of the tar or recovered acid thereon may,
after having been dried, be used as a source of sulphurous acid. When preparing
the mixture for this purpose care must be taken that sufficient carbon is supplied
either by employing excess of shale residue or by adding carbon from some other
source. The dried mixture for the evolution of sulphurous acid must be slowly
heated in a muffle or equivalent furnace or retort, to which is admitted a properly
regulated supply of air from the residue alum, or sulphate of alumina may be
prepared.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the system, mode, or manner in or under which the same is or may be used
or practically carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to me by the
herein before in part recited Letters Patent is, utilising acid tar obtained in the
manner set forth for the purpose of producing alum, sulphate of alumina, sulphate
of iron, and sulphurous acid, in the manner herein-before described.
In witness whereof, I, the said John Calderwood,, have hereunto set my hand
and seal, this Twenty-eighth day of December, One thousand eight hundred
and seventy-six.