PROCESS OF MANUFACTURING FROM KAOLIN OR OTHER ALUMINOUS EARTHS CONTAINING IRON A COMPOUND FOR PAPER MAKERS' Tan
Year: 1880

page_text: LETTERS PATENT to Robert Andrews Fisher, of the City and County of Phila-
delphia, and State of Pennsylvania, United States of America, Chemist, for
the Invention of "PROCESS OF MANUFACTURING FROM KAOLIN OR OTHER
ALUMINOUS EARTHS CONTAINING IRON A COMPOUND FOR PAPER MAKERS'
Tan"
led the 12th March 1880, and dated the 14th January 1880.
COMPLETE SPECIFICATION filed by the said Robert Andrews Fisher at the
Office of the Commissioners of Patents on the 14th January 1880.
☐ ROBERT ANDREWS FISHER, of the City and County of Philadelphia, and State of
"PROCESS OF MANUFACTURING
Pennsylvania, United States of America, Chemist.
FROM KAOLIN OR OTHER ALUMINOUS EARTHS CONTAINING IRON A COMPOUnd
FOR PAPER MAKERS' USE."
My Invention is a process for producing from kaolin, bauxite, or any other of
the commonly employed aluminous materials containing ferrous or ferric oxide, or
both, a white compound for paper makers' use, consisting essentially of sulphate of
alumina and sulphate zinc, containing more or less water, but richer in sulphate
of alumina than ordinary alum, and free from any persalt of iron, and so neutral
that its solution produces little or no effect upon artificial ultramarine blue, orange
mineral, the anyline dyes, and other colors used by paper makers.
The following description will enable any one skilled in the art to which my
Invention most nearly appertains to carry my Invention into practice.
The kaolin, bauxite, or other aluminous material is first to be treated with
sulphuric acid according to any one of the usual methods for producing from these
clays a solution of sulphate of alumina containing more or less iron.
The solution of sulphate of alumina and iron is allowed to settle, and the clear
liquor decanted into a lead lined tank or other convenient vessel, where it is
exposed to the action of a suitable reducing agent to convert any ferric oxide
that may be present into ferrous oxide. Any powerful reducing agent may be
employed.
Nasient hydrogen produced by electrolysis or other means, sulphuretted hydrogen,
or sulphurous acid, either set free directly in the liquid or previously generated and
then passed into the liquid, may be used for the purpose.
The liquid must be subjected to the action of the reducing agent until all ferrio
salts present have been converted into ferrous salts.

page_text: This accomplished, the next step in the process is to treat the solution with oxide
of zinc in order to completely saturate all free acid and produce a liquid which
does not materially effect mineral pigments and analine colors.
This treatment can be conveniently accomplished in a wooden tank or vessel
lined with lead, supplied with a steam coil or pipe by which the contents of the
vessel can be heated without diluting the same by condensed water.
The liquid is first heated to a temperature of 100° F., more or less, and a quantity
of oxide of zinc sufficient to produce the desired neutrality, introduced either in its
dry state or moistened with water.
The liquid is stirred during several minutes until all or a portion of the oxide of
zinc has dissolved. It now remains to test the neutrality of the solution. I find
artificial ultramarine blue to answer the purpose well.
The following is a convenient method:-
Dilute a few ounces of the solution to density of 12° B., more or less, and bring
to a temperature of 60° F., more or less, and place the same in a glass bottle or
other convenient vessel, add two or three grains of finely ground ultramarine blue
and shake the bottle.
If the blue color of the pigment is persistent sufficient oxide of zinc has been
employed; if on the contrary the color of the ultramarine blue is effected an
additional quantity of oxide of zinc must be added to the liquid contained in the
lead lined tank and the whole again agitated.
After the lapse of a few minutes a small portion of the liquid is to be again
tested as before with ultramarine blue.
These alternate operations of adding oxide of zinc to the liquid and then testing
a portion of the same with ultramarine blue (or other suitable test color) must be
repeated until the liquid is so neutral that it produces little or no effect on the
color.
As soon as this neutrality is obtained and the solution is evaporated to the
density of 48° B., more or less, the solution is run out into shallow vessels of stone,
metal, or wood.
When cool the cake is broken up into pieces and can be dried either by pro-
longed exposure to the air at ordinary temperatures, or more rapidly by artificial
heat.
Finally it may be ground in a mill of any suitable construction and packed in
the usual manner, or still further dried after coming from the mill or crushing
machine.
It is not essential although advantageous to the success of the process just
described that the aluminous solution should be exposed to the action of reducing
agents prior to treatment with oxide of zinc, as the aluminous solution may be first
treated with oxide of zinc and afterwards with reducing agents.
Having thus described my Invention I claim,-
The process for the manufacture from kaolin, bauxite, and similar aluminous
earths containing iron of a white compound, consisting essentially of sulphate of
alumina and sulphate of zinc free from ferric salts; which process consists in
treating a solution of sulphate of alumina with a reducing agent to convert ferric
into ferrous salts; and further, in treating said solution with oxide of zinc to
neutralize the free acid in the same, substantially as described.
In witness whereof, I, the said Robert Andrews Fisher, have hereunto set
my hand and seal, this Fifteenth day of December, A.D. 1879.