Improvements in the Production of Alkaline Phosphates in the Manufacture of Iron or Steel from Phosphoric Pig Iron.
Year: 1885

page_text: Improvements in the Production of Alkaline Phosphates in the
Manufacture of Iron or Steel from Phosphoric Pig Iron.
I THOMAS TWYNAM of 110 Grange Road East, Middlesboro' in the County of
York Analytical Chemist do hereby declare the nature of my said invention for
IMPROVEMENTS IN THE PRODUCTION OF ALKALINE PHOSPHATES IN THE MANU
FACTURE OF IRON OR STEEL FROM PHOSPHORIC PIG IRON, to be as follows:-
This Invention relates to the manufacture of an alkaline phosphoric slag (from
which soluble alkaline phosphates may be produced) during the manufacture of
iron or steel from phosphoric pig iron. According to my invention I propose to
add in the converter, or Siemens, or other furnace (which should be lined with
basic or neutral material) either trisodic or tripotassic phosphate or a phosphate
containing three or more equivalents of an alkaline base for each equivalent of
phosphoric acid which alkaline phosphates are preferably prepared as follows.
The insoluble phosphoric alkaline slag produced in a prior operation is fused
with a sufficient amount of an alkaline salt (for which purpose I always prefer to
use the carbonate) to give with the alkali already present in the slag at least three
equivalents of base for each equivalent of phosphoric acid.
Instead of the carbonate, the sulphate may be employed, or the slag may be
fused with an alkaline chloride with or without the presence of steam. The
resulting mass of tribasic alkaline phosphate mixed with oxides of iron and
manganese may be either employed directly in a subsequent operation in the
converter or furnace, or may be first extracted with water and afterwards obtained
nearly pure by evaporating or crystallizing the aqueous solution.
The trisodic or tripotassic phosphate is converted into the monobasic salt in the
converter or furnace from which by a subsequent fusion, the tribasic salt may be
again regenerated.
The metal treated should preferably be first desiliconized.
:

page_text: Manufacture of Iron or Steel from Phosphorio Pig Iron.
I, THOMAS TWYNAM of 110 Grange Road East, Middlesboro' in the County of
York, Analytical Chemist do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
This invention relates to the manufacture of alkaline phosphoric slags (from
which soluble alkaline phosphates may be produced) during the manufacture of
iron or steel from phosphoric pig iron.
I find that both alkaline carbonates and chlorides when employed to eliminate
phosphorus from pig iron during its conversion into iron or steel are very largely
volatilized by the great heat employed. The cooling effect of both these alkaline
salts upon the metal is also very great, in the case of the carbonate owing to
the dissociation of the salt, and in that of the chloride owing to its excessive
volatilization.
To overcome these drawbacks I propose to add in the converter or Siemen's
or other furnace employed, either trisodic or tripotassic phosphate or an alkaline
phosphate containing three or more equivalents of an alkaline base for every
equivalent of phosphoric acid, and which for the purpose of this specification
I. speak of as trisodic phosphate. This trisodic phosphate I prepare in actual
practice by taking the alkaline phosphoric slag obtained from a former operation
and which may be described as monosodic phosphate and fusing it with a sufficient
amount of an alkaline salt (for which purpose I always prefer to use the carbonate)
to give with the alkali already present in the original slag at least three equivalents
of base (Na, O) for each equivalent of phosphoric acid. This fusion may be made
either by running into the molten slag contained in a ladle or furnace the requisite
amount of alkali molten or otherwise. A convenient method of working is to run
the alkaline slag from the basic Bessemer or Siemens furnace into a basic or
neutrally lined ladle and to run the ladle to such a position that the alkaline
carbonate previously melted in a small basic lined furnace or cupola may be readily
run in to the ladle, or so that the contents of the ladle may be run in upon the
melted carbonate. The reaction is quickly effected and the resulting trisodic
phosphate slag (which is mixed with oxides of iron manganese &c.) may be used
direct as the basic addition made during the dephosphorisation of phosphoric pig
iron in a basic or neutrally lined converter or Siemens furnace. Or the fused mass
may be allowed to cool slowly when the upper portion will consist of nearly pure
alkaline salts, the lower portion containing the metallic oxides. Or the fused mass
may be crushed and digested in water to extract the trisodic phosphate, and any
excess of sodic salt, the phosphate being afterwards recovered by evaporation.
It will be seen from the above that in the furnace or converter used for conversion
of the pig iron the trisodic phosphate added is converted into the monosodic salt,
which by a subsequent fusion with alkali is reconverted into the trisodic salt.

page_text: In place of carbonate of soda the sulphate may be employed, but in this case
owing to the sulphur it contains, the resulting fused mass cannot be reused in the
converter. The chloride may also be employed aided by steam, but the decomposition
is less complete and the reaction takes place more slowly.
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,
1st The employment for the purification of phosphoric pig iron, during its
conversion into iron or steel in a basic or neutrally lined furnace or converter of
trisodic or tripotassic phosphate or of a phosphate containing at least three
equivalents of base for each equivalent of phosphoric acid.
2nd The production during the manufacture of iron or steel from phosphoric
pig iron of soluble alkaline phosphates by the addition of trisodic or tripotassic
phosphate in the converter or furnace and the subsequent fusion of the alkaline
phosphoric slag produced with a further quantity of an alkaline salt.
PHILIP M. JUSTICE,
Applicant's Agent.