PROCESS FOR PRODUCING A NEUTRAL COMPOUND OF SULPHATE OF ALUMINA AND ZINC FOR PAPER MAKERS' USE
Year: 1880

page_text: LETTERS PATENT to Robert Andrews Fisher, of the City of Philadelphia, and
State of Pennsylvania, United States of America, Chemist, for the Invention of
PROCESS FOR PRODUCING A NEUTRAL COMPOUND OF SULPHATE OF ALUMINA
AND ZINC FOR PAPER MAKERS' USE,"
"
COMPLETE SPECIFICATION filed by the said Robert Andrew Fisher at the
Office of the Commissioners of Patents on the 14th January 1880.
ROBERT ANDREWS FISHER, of the City of Philadelphia, and State of Pennsylvania,
United States of America, Chemist. "PROCESS FOR PRODUCING A NEUTRAL
COMPOUND OF SULPHATE OF ALUMINA AND ZINC FOR PAPER MAKERS' USE."
The object of my Invention is to produce a resulting product so neutral that a
moderately concentrated solution of the material produces little, if any, effect upon
the pigments known as ultramarine blue and orange mineral, or upon the various
aniline colors used in paper making.
The following description will enable any one skilled in the art to which my
Invention most nearly apertains to successfully carry out the process.
I first prepare a solution of sulphate of alumina by the action of sulphuric acid
upon alumina, kaolin, or other aluminous substance free from iron, following the
ordinary method required for the particular clay or aluminous material employed.
The relative proportions of aluminous material and sulphuric acid required, and
the time and temperature necessary to produce most economically the solution of
sulphate of alumina, will vary more or less with every variety of aluminous
material, and can be determined accurately only by experiment.
It may be stated in general terms that one part of the aluminous material will
require about two parts by weight of sulphuric acid, of density 50° B.
My Invention does not, however, consist in any improvement in the preparation
of solutions of sulphate of alumina, but in the subsequent treatment of such
solutions obtained by any of the ordinary methods.
After the preparation of the sulphate of alumina solution it is allowed to settle,
the clear liquor having a density of 25° Baumé, more or less, is then drawn off into
a suitable vessel for subsequent treatment (a wooden vessel lined with lead and
Price 91

page_text: furnished with a metallic worm or coil with proper appliances for passing through it
a current of steam, answers the purpose well).
The solution is then heated to the temperature of 100° F., more or less, after
which oxide of zinc, either in its dry state or moistend with water, is introduced
and the liquid stirred until all, or nearly all, of the oxide of zinc has dissolved.
The quantity of oxide of zinc necessary to produce a solution of the required
neutrality will depend upon the proportion of acid contained in the sulphate of
alumina solution.
'
In some cases a quantity of oxide of zinc equal in weight to two (2) per cent. of
the weight of the resulting zinc-sulphate of alumina, or even less might suffice. A
very much larger quantity might be necessary if the original solution of sulphate of
alumina should contain much free acid.
A convenient method of determining whether a sufficient quantity of oxide of
zinc has been used, is by observing the action of the zinc alumina solution upon the
pigment known as artificial ultramarine blue.
For this purpose, into a glass stoppered bottle or other convenient vessel, are put
a few ounces of the solution previously reduced with water to density of 12° Baumé,
more or less, and brought to the temperature of 60° F., a few grains (two to five,
according to the amount of the liquid used) of finely ground ultramarine blue are
then introduced, and the contents of the bottle shaken. If a sufficient quantity of
oxide of zinc has been employed, the color of the ultramarine blue remains for a
long time unaltered.
If on the contrary the color of the pigment is soon changed or disappears more
oxide of zinc must be added to the zinc alumina solution contained in the lead lined
tank, and after a few minutes stirring, the liquid is again tested as before, with
ultramarine blue.
These alternate operations of adding oxide of zinc and testing the resulting liquid
with ultramarine bluc, must be repeated until the liquid at a density of 12° B.,
more or less, and at temperature of say 60° F., fails to effect the color of ultramarine
blue even after many hours' contact.
When this point shall have been reached, the zinc alumina solution is to be
evaporated (conveniently but not necessarily in the same tank in which it has been
treated with oxide of zinc) to the density of 48° Baumé, more or less, and then run
out upon floors of lead, stone, or other suitable material.
Upon cooling there is formed a moist cake.
This cake is to be removed by shovel or other convenient means, and exposed for
some days to the action of the air, or in an artificially heated drying room, until
sufficiently hard to be conveniently reduced by a mill or other machine to a coarse
powder; subsequently the material is packed in barrels for use, or further dried at
an artificial temperature to expel more moisture, and thereby increase the percentage
of sulphate of alumina.
Having thus described my Invention I claim,―
The process for the production of a neutral compound, consisting essentially of
sulphate of alumina and zinc, for paper makers' use, by treating a solution of
sulphate of alumina with oxide of zinc 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.