IMPROVEMENTS IN METHODS OF REMOVING IRON FROM FERRUGINOUS ALUMINOUS SOLUTIONS, AND IN METHODS OF RECOVERING OR PURIFYING WASTE OR SPENT PLUMBIC DIOXIDE CONTAINING IRON
Year: 1881

page_text: LETTERS PATENT to Conrad Semper and Constantine Fahlberg, both of the
City of Philadelphia, in the State of Pennsylvania, United States of
America, Chemists, for an Invention of "IMPROVEMENTS IN METHODS OF
REMOVING IRON FROM FERRUGINOUS ALUMINOUS SOLUTIONS, AND IN
METHODS OF RECOVERING OR PURIFYING WASTE OR SPENT PLUMBIC
DIOXIDE CONTAINING IRON.”
COMPLETE SPECIFICATION filed by the said Conrad Semper and Constantine
Fahlberg at the Office of the Commissioners of Patents on the 20th
December 1881.
CONRAD SEMPER and CONSTANTINE FAILBERG, both of the City of Philadelphia,
in the State of Pennsylvania, United States of America, Chemists. "IMPROVE-
MENTS IN METHODS OF REMOVING IRON FROM FERRUGINOUS ALUMINOUS
SOLUTIONS, AND IN METHODS OF RECOVERING OR PURIFYING WASTE OR SPENT
PLUMBIC DIOXIDE CONTAINING IRON."
The object of our Invention is to provide a means of removing the oxides of iron
froin solutions in which, as for instance aluminous solutions, the presence of iron is
deleterious to the product to be manufactured therefrom, or is objectionable in the
process by which such product is obtained.
Our Invention consists in the treatment of ferruginous solutions with plumbic
dioxide for the precipitation therefrom of iron, as plumbate of iron, as hereinafter
described and claimed.
Our Invention further consists in treating the spent plumbic dioxide resulting
from the first named process with such agent as will re nove the iron therefrom
without destroying the plumbic dioxide, as is hereinafter described and claimed.
. We do not restrict our Invention to the manufacture of alum or aluminous
[Price AdI

page_text: products, as it is obvious that it is applicable to the treatment of a ferruginous
solution of a soluble salt of any alkali, alkaline earth, or metallic base, provided
only that such alkali, alkaline earth or metallic base is not acted upon or materially
precipitated by plumbic dioxide.
We do not restrict our Invention to the use of plumbic dioxide alone, as we
contemplate the use of such compounds of lead as contain plumbic dioxide, and
the use of such compounds of lead as may be converted into plumbic dioxide in
the ferruginous solution treated.
In cases where the acid of the salt, from the solution of which it is desired to
remove the iron, forms with lead an insoluble lead salt,, the resulting purified
solution will contain no lead, or at most only a trace thereof.
If the acid of said salt is of such a nature as to form with lead a soluble lead
salt, a small quantity of lead may go into solution, especially if the iron present is
in the ferrous state; in such cases, where lead is objectionable, it may be removed
by any of the well known processes, such as by treating the solution with
sulphuretted hydrogen, or with sulphuric acid, or with a sulphate of the material
of which the solution treated consists.
-Should the iron present in the solution treated by our process be in the ferrous:
state, part of the plumbic dioxide employed will be decomposed in oxidizing said
ferrous oxide into ferric oxide, as we have ascertained that the iron is precipitated
by plumbic dioxide as ferric plumbate.-
To avoid the loss of plumbic dioxide resulting from such oxidation, other cheaper
oxidizing agents may be successfully employed.
In most cases the loss of plumbic dioxide by reason of such oxidation is so small
as to be immaterial from an economical point of view; it is however advisable to
resort to previous oxidation of the ferrous oxide into ferric oxide in all cases
where soluble lead salts can be formed in the subsequent treatment of the
ferruginous solution with plumbic dioxide.
The temperature of the solution to which the plumbic dioxide is to be added is
not essential, but we prefer cold solutions.
: The strength of the solutions to be treated is unessential, but preferably they
should be as concentrated as possible.
The plumbic dioxide should be well washed and freed from foreign matter.
It is advantageous to have the solutions to be treated by plumbic dioxide for
removal of iron therefrom clear and free from mechanically suspended impurities,
as these impurities would remain with the plumbic dioxide, by which it would
eventually become objectionably charged with foreign matter and unfit to be
recovered and used for removing iron from new ferruginous solutions.
It is desirable that the solutions of the salts to be freed from iron should be
as neutral as possible and should not contain a large excess of acid, otherwise the
complete precipitation of the iron could only be effected by large quantities of the
precipitating agent.
The following is a convenient method of practising our Invention, viz., a
concentrated solution of sulphate of alumina obtained from bauxite or other
aluminous material or of any soluble salt of a metal, alkaline earth, or alkali
made in the usual manner and containing iron is first freed by any of the well
known methods from its insoluble impurities; it is then treated, should the iron be
present as ferrous oxide, with a small quantity of a solution of chloride of lime, or
other convenient oxidizing agent, heated, and left to cool.
If however the iron be present as ferric oxide, or if the quantity of ferrous oxide
present is small, this application, of heat and oxidation is not necessary and should
be omitted.
A certain quantity of plumbic dioxide is then added, which according to the
amount of the iron present in the solution aforesaid, should be from 5 to 20 per cent.
more or less of the salt present in the said solution, and the mixture briskly
stirred for some time., The solution is then separated from the insoluble parts by
any well known method, such as by letting it, subside or by passing it through a

page_text: filter or filter press; the clear solution will be found to be freed entirely or almost
entirely from iron.
This solution can be utilized as may be desirable, or it may be concentrated and
left to crystallize, or it may be run into a cake, or evaporated to dryness.
The insoluble part which contains the iron may be washed with water to remove
the adhering salt solution, and this water containing the salt in the solution may
either be added to the solution first obtained or be utilized in the next operation.
In order to revive the spent plumbic dioxide and to remove from it the iron or
to separate the plumbic dioxide from the said ferric plumbate and prepare it for a
fresh application, it is, after washing it thoroughly to remove the adhering salt
solutions, stirred up with dilute nitric acid, left to settle, and after removing the
first liquor, which is an acid solution of nitrate of iron, washed for a sufficient time
until the last traces of nitric acid are removed.
The plumbic dioxide so recovered will be ready for use in the treatment of new
ferruginous solutions.
The quantity of nitric acid is to be regulated by the quantity of iron to be
removed; an excess is always desirable.
We do not confine ourselves to nitric acid alone for this revivification of the
spent plumbic dioxide, but we can employ any other acid or agent which will
remove the iron from the ferric plumbate without decomposing in the course of
such treatment the freed plumbic dioxide.
Having thus described our Invention, we claim,—
1. The method of removing iron from a ferruginous solution of the salt of a
metal-alkali or alkaline earth, which consists in treating said ferruginous solution
with plumbic dioxide, for the purpose specified.
2. The method of manufacturing sulphate of alumina or aluminous cake, free or
almost free from iron, which consists in treating ferruginous aluminous solutions
with plumbic dioxide, for the purpose specified.
3. The process of purifying waste plumbic dioxide and ferric plumbate
produced in the process of precipitating iron from ferruginous solutions, which
consists in treating said waste mass with nitric or other acid or acid salt for the
removal of the iron therefrom, as specified.
In witness whereof, we have hereunto set our hands and seals, this Thirtieth
day of November, Anno Domini, One thousand eight hundred and eighty
one [1881]
CONRAD SEMPER.
(L.S.)
CONSTANTINE FAHLBERG. (L.S.)