IMPROVEMENT IN THE TREATMENT OF PHOSPHATIC SLAGS
Year: 1884

page_text: COMPLETE
DEECIFICATION.
I, CARL SCHEIBLER, Doctor of philosophy and Professor, residing Buchen-
Strasse 6 Berlin, Prussia, German Empire do hereby declare the nature of my said
invention for "IMPROVEMENT IN THE TREATMENT OF PHOSPHATIC SLAGS," and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention relates to the utilization of phosphatic slags, especially those
obtained by the dephosphorization of iron by the Thomas-process, and has for its
object to extract therefrom the phosphoric acid as phosphate of lime to be used
for agricultural purposes and to obtain a residue rich in iron and manganeso which
may be returned to the blast-furnace. The said invention consists in concentrating
both, the phosphoric acid and the iron and manganese within the slag itself in
such a manner that the slag can easily be separated in two portions one of which
contains the greater part of the phosphoric acid and but little iron, whereas the
other portion holds the greater part of the iron and manganese nearly free from
phosphoric acid.
I have found by a series of experiments made on a large scale, that, when fluid
phosphatic slags are kept for some time in liquid state and allowed to slowly cool
down without being moved, a transposition of the constituents of the same takes
place in such a manner that the upper part of the liquid mass grows richer and
richer in phosphoric acid, whilst the iron and manganese settle towards the bottom.
By separating the mass into an upper portion and a lower one, the greater part of
the phosphoric acid contained in the bulk of slug will be found in the former,
whereas the latter contains the greatest part of the iron and manganese present
with but little phosphoric acid.
By thus proceeding, I have for instance separated slags obtained by the Thomas-
process into one portion containing 35 p. c. of phosphoric acid with 57 p. c. of
Jime, and another portion containing only 7, p. c. of phosphoric acid with 37 p. c.
of lime, but 33., p. c. of iron, the totality of iron present in the slag having
been but 13., p. C
In another experiment, where I caused the cooling to pass less slowly, that
portion which tiist solidified, contained 16, p. c. of phosphoric acid, 14. p. c.
of iron, and 45., p. c. of lime, whereas the liquid portion removed therefrom,
contained 21. p. c. of phosphoric acid, 10., p. c. of iron, and 52., p. c. of lime.

page_text: It is evident by these experiments that the separation of the constituents will
be the more efficaceous the longer the slag is kept in liquid state and the more
slowly the cooling is allowed to take place. By maintaining the slag sufficiently
long in liquid condition, i.c. by retarding as much as possible its cooling down,
a separation of the same takes place into phosphate of lime, and into ferrate and
manganate of lime nearly free from phosphoric acid.
In carrying out my invention into practice, I prefer to pour the liquid slag into
vessels coated with a bad conductor of heat, and to put these vessels, when filled,
in a room protected against the access of cold air, where they remain until the
outer surface of the slag contained therein, begins to solidify. The inner fluid
mass is then removed; it contains the greater part of the phosphate of lime and is
utilized for the manufacture of manure. The outer crust consisting of the portion
rich in iron and manganese may be returned to the blast-furnace.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
The described method of concentrating the phosphoric acid contained in the
phosphatic slag on the one part, and the iron and manganese on the other part, so
as to permit the same of being removed separately, this method consisting in
exposing the fluid slag to slow cooling whereby a transposition of the constituents
forming the slag takes place.
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