provements in the Manufacture of Ingot Iron and Steel.
Year: 1889

page_text: Date of Application, 7th Aug., 1889
Complete Specification Left, 6th May, 1890-Accepted, 7th June, 1890
PROVISIONAL SPECIFICATION
Improvements in the Manufacture of Ingot Iron and Steel.
I, THOMAS TWYNAM of 7 Marlborough Crescent Bedford Park, Chiswick, W.
Metallurgical Chemist do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved method of increasing the yield when working
the Bessemer process as carried out in neutral and basic lined vessels in presence of a
basic slag.
I find that by adding to the charge of pig iron in the converter a certain amount of
oxide of iron mixed with about a fifth of its weight of coke dust or other convenient
form of carbon, that the oxide so added is largely reduced to metal during the blow,
more especially during the carbon period.
When using my process in conjunction with the ordinary basic Bessemer process,
I prefer to add the mixture of oxide and carbon when the silicon has been burnt
out of the pig metal, or it may very conveniently be charged into the vessel with the
lime and the molten pig iron run in upon it.
The oxide and carbon used should both be in a fine state of division and should be
well mixed together.
Roll, mill, or haminer scale are very suitable for the purpose when fairly free from
sand; iron ore when used should be roughly ground to bring it to a fit state of
division.
As the reduction takes place most readily in presence of molten basic slag, 1 some-
times find it convenient to add some roughly broken basic slag with the oxide or scale
mixture. Care should be taken not to add the oxide too late in the blow or to add
too great an excess as there would be danger of the resulting metal being wild, and
also of chilling the charge.
Instead of adding the oxide and carbon in a loose state, they may be previously
mixed together and moulded into bricks, using tar as a binding material. In this
case the bricks may either be added when charging or may be thrown into the vessel
when the charge has been blown for a few minutes; so as to have some molten slag
present in the vessel, into which the bricks may sink.
When, instead of using a pure iron oxide, a manganiferous ore is used, manganese
is also reduced into the bath.
Dated this fith day of Aust 1880
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Ingot Iron and Steel.
I, THOMAS TWYNAM of 7 Marlborough Crescent Bedford Park, Chiswick, W.
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 :-
This invention relates to an improvement in the manufacture of ingot iron or steel
when working the Bessemer process as carried out in basic or neutral lined vessels
by which a larger yield of steel is produced.
I find that by adding with the charge of pig iron in the converter a certain amount
of oxide of iron previously intimately mixed with not less than one-fifth of its weight
of coke dust or other convenient form of carbon that the iron contained in the oxide
so added is nearly wholly reduced to metal during the process of conversion, so
DAT

page_text: increasing the yield of steel obtained and lessening to some extent the length of the
afterblow.
When using this process in conjunction with the ordinary basic Bessemer process
I prefer to add the mixture of oxide of iron and carbon either when the silicon and
about one-third of the carbon has been burnt out of the pig metal or it may most
conveniently be charged into the converter with the lime and the molten pig iron
subsequently run in upon it.
The oxide of iron and carbon used should be both in a fino state of division before
being mixed together, they may after mixing, be charged into the vessel in the loose
condition but I always prefer to first roughly form them into bricks using tar as a
binding material and subsequently caking the mixture.
I find good bricks may be made by coking in moulds a mixture of iron scale or
oxide and small caking coal in such proportion as to leave about 30% (thirty per
cent.) of carbon in the brick after coking.
I have found mill or hammer scale to be the most suitable oxide to use for the
purpose.
Iron ore when used must be fairly low in silicious matter and should be roughly
ground before use. Sulphur must be as far as possible absent both from the
oxide and from the coke or carbon employed, but the oxide of iron may be
phosphatic.
When, instead of using a pure oxide of iron, a manganiferous ore is employed,
manganese will also be found to be reduced into the bath to some extent, but is
generally reoxidized during the conversion.
Care should be taken not to add the mixture of oxide and carbon too late in the
blow or to add too great an excess as there would be danger of the resulting metal
being mild, and also fear of chilling the charge.
I have found when working charges of five tons of pig iron that from 7 to 10 per
cent. of scale made into bricks, containing about thirty per cent. of their weight of
carbon, may be added, and in this way the yield of ingots has been increased by fully
five per cent., the afterblow also being somewhat lessened. I do not however give this
as the maximum amount which may be added, as it will depend on the chemical
composition of the pig iron and the weight of the charge to be converted.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In the manufacture of ingot iron and steel in basic or neutral lined Bessemer
converters, the addition of a mixture of oxide of iron and carbon for the purpose of
increasing the yield, substantially as described.
1000
THOMAS TWYNAM.