IMPROVEMENTS IN THE MANUFACTURE OF ALUMINA FROM SULPHATE OF ALUMINA, OR CERTAIN OTHER SALTS OF ALUMINA
Year: 1883

page_text: ETTERS PATENT to William Phillips Thompson of the firm of W P Thompson
& Boult Agents for Foreign Patent Solicitors 6 Lord Street Liverpool in the
county of Lancaster Civil Engineer for an Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ALUMINA FROM SULPHATE OF ALUMINA, OR CERTAIN
OTHER SALTS OF ALUMINA a communication to him from James Douglas
Darling a person residing in the City, county, and State of New York.
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson
at the Office of the Commissioners of Patents on the 28th March 1883.
WILLIAM PHILLIPS THOMPSON of the firm of W. P. Thompson & Boult Agents
for Foreign Patent Solicitors 6 Lord Street Liverpool in the county of Lancaster
Civil Engineer. "IMPROVEMENTS IN THE MANUFACTURE OF ALUMINA FROM
SULPHATE OF ALUMINA OR CERTAIN OTHER SALTS OF ALUMINA "-A communi-
cation to me from James Douglas Darling a person residing in the City, County,
and State of New York.
The following is a copy of the communication as received by me.
I have invented a new and useful improvement in the process of obtaining
Alumina from Alum or from Aluminium sulphate
The method that has been for a long time used consists in dissolving the Alum or
Aluminium Sulphate in water and precipitating the Alumina by adding an excess
of Alkali to the solution. A gelatinous hydrated precipitate of Alumina has been
thus obtained mingled with which are more or less impurities
This precipitate has been then subjected to a washing process which when
continued for a considerable length of time, usually several months, frees it from
those impurities sufficiently to make it alumina suitable to be manufactured into
Aluminium by the present well known processes and for other useful purposes
A patent has also been obtained by James Webster dated June 14 1881 and
No 2680. for an improvement in the production of Alumina suitable for the manu-
facture of Aluminium and other useful purposes, on reference to which the method
employed by him will be found fully described

page_text: -
The following is a full and accurate description of the process which I employ :-
I take a given quantity of Aluminium sulphate or Ammonium Alum, potash
alum, sodium alum or other salts or compounds of alum, and dissolve it in a sufficient
quantity of water to form a concentrated solution.
To this I add an excess of alkali and by this means all the alumina contained in
said solution is precipitated as a gelatinous hydrated precipitate of alumina mingled
with impurities
This precipitate should be collected on a filter or other suitable apparatus for
draining the same and thus be drained and dried.
I then submit this precipitate to a red heat or any higher heat, long enough to
reduce it to a calcined oxide. I then wash this calcined oxide with water which
will within a very short time in comparison with the old process above referred to,
remove enough of the impurities to leave the Alumina sufficiently pure to be
manufactured into Aluminium by the present well known processes, and for other
useful purposes
I would however recommend that Ammonium alum or Aluminium sulphate be
used and the following process employed.
In producing the gelatinous hydrated precipitate from Ammonium alum or from
Aluminium sulphate I use as an alkali ammonia and I recommend that this be
used either in the form of concentrated liquid ammonia or by passing ammonia gas
through said solution
This precipitate I drain and dry in the manner already described, and then
subject it to a red heat, or any higher heat, long enough to reduce it to a calcined
oxide and substantially drive off the sulphate of ammonia which will generally
require from fifteen minutes to a half hour. The calcined oxide thus produced
from Ammonium alum or from Aluminium sulphate is alumina sufficiently pure to
be manufactured into Aluminium by the present well known processes, or for other
useful purposes.
.
Because of the difficulty of obtaining pure ammonium alum or pure aluminium
sulphate it is advisable to place this calcined oxide in a suitable vat or vessel and
wash out with water (hot water being most suitable) any sulphates or other
impurities that may remain therein, and then collect and dry the same
The application of a red hot or any higher heat to the gelatinous hydrated
precipitate obtained from Ammonium alum or from Aluminium sulphate for a
long enough time, produces a calcined oxide which is substantially free of sulphates
while the application of such heat however long applied to the gelatinous hydrated
precipitates of other alums simply produces a calcined oxide without driving off
the sulphates.

page_text: :
SPECIFICATION in pursuance of the conditions of the Letters Patent filed.
by the said William Phillips Thompson in the Great Seal Patent Office on
the 27th September 1883.
WILLIAM PHILLIPS THOMPSON of the firm of W. P Thompson and Boult Agents
for Foreign Patent Solicitors 6 Lord Street Liverpool in the county of Lancaster
Civil Engineer " IMPROVEMENTS IN THE MANUFACTURE OF ALUMINA FROM
SULPHATE OF ALUMINA OR CERTAIN OTHER SALTS OF ALUMINA a communi-
cation to me from James Douglas Darling a person residing in the city county,"
and State of New York
"
The following is the description of the invention exactly as received from my
foreign correspondent.
"I have invented a new and useful improvement in the process of obtaining
alumina from alum or from aluminium sulphate.
"The method that has been for a long time used, consists in dissolving the alum
or aluminium sulphate in water and precipitating the alumina by adding an excess.
of alkali to the solution. A gelatinous hydrated precipitate of alumina has been
thus obtained mingled with which are more or less impurities.
"This precipitate has been then subjected to a washing process which when'
continued for a considerable length of time, usually several months, frees it from
thoso impurities sufficiently to make it alumina suitable to be manufactured into
aluminium by the present well known processes and for other useful purposes.
"A patent has also been obtained by James Webster dated June 14 1881 and
N° 2580, for an improvement in the production of alumina suitable for the manu-
facture of aluminium and other useful purposes, on reference to which the method
employed by him will be found fully described.
:
"The following is a full and accurate description of the process which I employ.
"I take a given quantity of aluminium sulphate or ammonium alum, potash
alum, sodium alum, or other salts or compounds of alum, and dissolve it in a sufficient'
quantity of water to form a concentrated solution.
"To this I add an excess of alkali and by this means all the alumina contained in
said solution is precipitated as a gelatinous hydrated precipitate of alumina mingled
with impurities.
"This precipitate should be collected on a filter or other suitable apparatus for
draining the same and thus be drained and dried.
"I then submit this precipitate to a red heat, or any higher heat, long enough
to reduce it to a calcined oxide. I then wash this calcined oxide with water which
will within a very short time in comparison with the old process above referred to,
remove enough of the impurities to leave the alumina sufficiently pure to be
manufactured into aluminium by the present well known processes, and for other
useful purposes.
:
"I would however recommend that ammonium alum, or aluminium sulphate be
used and the following process employed.
"In producing the gelatinous hydrated precipitate from ammonium alum, or from
aluminium sulphate, I use as an alkali ammonia, and I recommend that this be
used either in the form of concentrated liquid ammonia or by passing ammonia gas
through said solution.
"This precipitate I drain and dry in the manner already described and then
subject it to a red heat, or any higher heat, long enough to reduce it to a calcined
oxide, and substantially drive off the sulphate of ammonia which will generally
require from fifteen minutes to a half hour. The calcined oxide thus produced
from ammonium alum or from aluminium sulphate is alumina sufficiently pure to
be manufactured into aluminium by the present well known processes, or for other
useful purposes.

page_text: "Because of the difficulty of obtaining pure ammonium alum or pure aluminium
sulphate, it is advisable to place this calcined oxide in a suitable vat or vessel
and wash out with water (hot water being most suitable) any sulphates or
other impurities that may remain therein and then collect and dry the same.
The
application of a red or any higher heat to the gelatinous hydrated precipitate
obtained from ammonium alum or from aluminium sulphate for a long enough
time, produces a calcined oxide which is substantially free of sulphates, while the
application of such heat however long applied to the gelatinous bydrated preci-
pitates of other alums, simply produces a calcined oxide without driving off the
sulphates.
"I am aware that the above described processes of precipitation of a gelatinous
hydrated precipitate have been already used, and I hereby disclaim the same.
"I am also aware that heat has been applied directly to ammonium alum, and to
aluminium sulphate for the purpose of producing alumina and I disclaim such
application.
"I am also aware that heat has been applied to the above described gelatinous
hydrated precipitates for the purpose of expelling water from them and I disclaim
the application of heat, or of a red or higher beat to said precipitates for that
purpose.
"I am also aware that the said gelatinous hydrated precipitates have been cleansed
from sulphates and other impurities by leaching the same with water and I disclaim
any such use of water."
Having now described the invention as communicated to me I wish it to be
understood that what I desire to protect under the Letters Patent is :-
"1st. The process of producing alumina from ammonium alum, potash alum, sodium
alum, or any salt or compound of alum, or from aluminium sulphate, by
subjecting the above described gelatinous hydrated precipitate obtained therefrom
to a red or higher heat for so long a time as shall convert the said precipitate into
a calcined oxide, and then using water upon said calcined oxide for the purpose of
substantially leaching therefrom the sulphates or other impurities contained therein,
substantially as above described.
"2nd The process of subjecting the above described gelatinous hydrated precipitate
obtained from ammonium alum or from aluminium sulphate to a red or
higher heat for so long a time as shall substantially expel from it the sulphate of
ammonia contained therein, substantially as above described.
"
3rd. The process of producing alumina from ammonium alum, or from aluminium
sulphate, by subjecting the above described gelatinous bydrated precipitate
obtained from ammonium alum or from aluminium sulphate, to a red or higher
heat for so long a time as shall convert it into a calcined oxide, and shall substan-
tially expel from it the sulphate of ammonia contained therein, and then using
water upon said calcined oxide for the purpose of substantially leaching therefrom
the remaining sulphates or other impurities, substantially as above described.
"4th. The use of water upon any of the above described calcined oxides to leach
therefrom the sulphates or other impurities, substantially as above
described."
In witness whereof I the said William Phillips. Thompson have hereunto set
my hand and seal this twenty sixth day of September in the year of our Lord
one thousand eight hundred and eighty three.