Improvements in the Purification of Iron, and of Phosphatic Ferruginous Slags.
Year: 1886

page_text: Improvements in the Purification of Iron, and of Phosphatic
Ferruginous Slags.
I THOMAS TWYNAM of 54 Minford Gardens West Kensington Park, in the
County of Middlesex, Metallurgical Chemist, do hereby declare the nature of this
invention to be as follows:-
I effect the purification of pig iron and simultaneously the purification of the
ferruginous phosphatic slag obtained in the Thomas Gilchrist process of steel
manufactured by causing the metalloids contained in the melted pig iron to act
upon and reduce the metallic oxides contained in the phosphatic slag thus oxidizing
and transferring from the metal to the slag the metalloid impurities contained in
the pig iron at the same time removing the metallic oxides from the slag.
When a phosphoric pig iron low in silicon is employed the basic slag, molten or
otherwise, is run or thrown into the melted phosphoric pig iron on the hearth of
a Siemens or other basic lined furnace or vessel, or the operation may be reversed,
the pig iron being run in upon the slag. The phosphorus in the pig iron is
oxidized to phosphoric acid at the expense of the metallic oxides contained in the
added basic slag, the resulting slag containing far less metallic oxides than the
added slag and being at the same time much richer in phosphoric acid. If there
be any considerable amount of silicon in the pig iron treated or if a rich silicious
pig be purposely employed there is considerable danger when working as above
described of reducing the phosphoric acid in the added basic slag simultaneously
with the metallic oxides, in this case I prefer to proceed as follows.
The basic slag is added to the pig iron (or vice versa) in such proportion that the
silicon of the metal will reduce not only the metallic oxides but also the phosphoric
acid contained in the slag, the resulting silicious slag is run off as useless and
a fresh quantity of basic slag added or run in upon the now desiliconized phosphoric
bath of metal, or the metal may be run in to a furnace or vessel containing the
[Price Fid

page_text: molten slag, in either case the phosphorus in the metal will react upon the metallic
oxides as above stated. The silicon may be removed from the original silicious pig
employed, in an acid lined furnace or vessel but when the phosphorous has to be
removed from the metal a basic lined furnace or vessel must be preferably
employed.
Instead of adding fresh basic slag to the desiliconized metal obtained by the
above described process, the desiliconized metal may be employed direct for steel
manufacture in the basic Bessemer or Siemens process, the absence of silicon being
very advantageous to the wear of the basic lining.

page_text: Ferruginous Slags.
I THOMAS TWYNAM of 54 Minford Gardens West Kensington Park, in the
County of Middlesex Metallurgical 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 :-
I effect the purification of pig iron and simultaneously the purification of the
ferruginous phosphatic slag obtained in the Thomas Gilchrist or other process of
steel manufacture, by causing the metalloids contained in melted pig iron to act
upon and reduce the metallic oxides contained in the phosphatic slag thus oxidizing
and transferring from the metal to the slag the metalloid impurities contained in
the pig iron at the same time removing the metallic oxides from the slag.
When a phosphoric pig iron low in silicon is employed, the basic slag molten or
otherwise is run or thrown into the melted phosphoric pig iron on the hearth of
a Siemens or other basic lined furnace or vessel, or the operation may be reversed,
the pig iron being run in upon the slag contained in any suitable basic or neutrally
lined furnace or vessel. The silicon and more or less of the carbon and phosphorus
contained in the pig iron are oxidized at the expense of the metallic oxides
contained in the added basic slag, the resulting slag containing far less metallic
oxides than the added slag and being also richer in phosphoric acid, the pig iron
after being thus acted upon is low in silicon and very suitable for use in the basic
process. If there be any considerable amount of silicon in the pig iron treated or
if a rich silicious pig be purposely used there is considerable danger when working
as above described of reducing some of the phosphoric acid in the added basic slag
simultaneously with the metallic oxides, in this case I prefer to proceed as follows.
The basic slag is added to the silicious pig iron (or vice versa) in such proportion
that the silicon of the metal will reduce not only the metallic oxides but also the
phosphoric acid contained in the slag, the resulting silicious slag is run off as
useless, and a fresh quantity of basic slag added or run in upon the now
desiliconized phosphoric bath of metal, or the metal may be run in to a furnace or
vessel containing the molten slag, in either case the phosphorus and carbon left in
the metal will react upon the metallic oxides as above stated. The reaction
between the phosphorus and carbon contained in pig metal is however not so
energetic as that of silicon upon the metallic oxides contained in slags.
Instead of adding fresh basic slag to the desiliconized metal obtained by the
above described process the desiliconized metal may be employed direct for steel
manufacture in the basic Bessemer or Siemens process, the absence of silicon being
very advantageous to the wear of the basic lining, while the resulting slag being
through the absence of silicon in it, higher in phosphoric acid, is also of more value
or agricultural purposes.
If the pig metal treated be a silicious one but not phosphatic, I treat it as before
described in a basic or neutrally lined furnace or vessel with the said basic slag.
Upon the removal of the silicon and more or less of the carbon, a practically pure
arbide of iron is left, which is well suited for some kinds of castings and for other

page_text: purposes; in this case such a proportion of the basic slag should be added to the
silicious metal that the resulting slag should at no time contain more than twenty
to twenty five per cent of silica as if more than this quantity be present phosphorus
will be introduced into the metal owing to the reduction of the phosphoric acid.
When removing silicon by the above process I use a furnace or vessel having
either a basic or a neutral lining, if the latter be employed it may advantageously
be made of chrome iron ore made coherent by the process described in my
specification No. 8358 of 1886.
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 hereinbefore described improvements in the purification of iron and of
phosphatic ferruginous slags substantially as and for the purposes set forth.