Improvements in the Manufacture of Steel and Ingot Iron by the Basic Process.
Year: 1887

page_text: Date of Application, 23rd Aug., 1887.
Specification Accepted, 23rd Sept., 1887.
Improvements in the Manufacture of Steel and Ingot Iron by the
Basic Process.
I. PERCY CARLYLE GILCHRIST. of Palace Chambers Bridge Street, in the City of
Westminster Metallurgist 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 :—
Heretofore it has been customary when working the basic process in an open hearth
furnace to charge with the pig iron employed a certain amount of solid scrap iron or
steel in a cold or partially heated state and with these are charged the necessary
amount of lime or limestone. A great disadvantage of this method of procedure
consists in the fact that the scrap takes longer to melt than the pig iron while when
both of these are in a molten state the lime or limestone may still remain in an
unfluxed condition and consequently not capable of acting to the best advantage.
The object of my present invention is to obviate these and certain other objectionable
features in the process.
According to my present invention I propose to charge a basic lined
open hearth
furnace with pig iron and lime or limestone in the ordinary way but without the
addition of scrap and with a smaller percentage of lime than is usually employed or
than would be necessary to wholly purify the charge of pig.
While this charge is being melted I blow in a basic Bessemer converter sufficient
pig iron to form the rest of the charge for the open hearth furnace this pig iron being
preferably phosphoric; a considerable excess of lime is added in the converter. Thus
if the charge be made up of 75 per cent of pig iron melted on the bed of the open
hearth furnace and 25 per cent of metal added molten from the basic converter the
pig iron employed containing about 5 to 1 per cent of silicon and about 2 per cent
of phosphorus then to the weight of the pig melted in the open hearth 5 to 10 per cent
of its weight of lime in the form of limestone may be added and to the pig iron blown
in the basic converter about 20 per cent of its weight of lime may be added. When
the charge in the open hearth furnace is melted or while it is yet in a semi-molten
condition I run into the open hearth furnace the blown charge from the Bessemer
converter including the slag which though in a thoroughly heated or fluxed condition

page_text: open
still contains a quantity of free or uncombined lime which serves for the purification
of the charge in the open hearth furnace. In this manner the scrap or pure iron
instead of being added cold to the pig charged in the open hearth is practically made
from pig in the converter and is added in a molten state to the charge in the
hearth, the requisite lime being also introduced in a fluxed condition and the time
required to purify the charge is considerably shortened thereby. The amount of ore
required to purify the charge in the open hearth will also be considerably lessened as
the oxides in the basic slag introduced with the blown metal serve equally as well
as ore to purify the melted pig thus both lessening the waste and the time required.
I am aware that it is not new to treat pig iron in an acid or silicious lined Bessemer
converter and subsequently transfer the charge to a basic lined open hearth furnace.
It has also been proposed to first treat the metal in a basic lined Bessemer converter
and then transfer it to an acid lined open hearth and various other combinations of
furnaces have been proposed and I do not claim such combinations as forming the
subject of my present invention.
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 improvement in the manufacture of steel and ingot iron by the basic process
which consists in charging a basic lined open hearth furnace with a portion of the
metal to be converted and with a portion of the basic material necessary for its
purification and when said charge is in a molten or semi-molten state running in
thereon from a basic Bessemer converter a molten charge together with the basic
slag which has been formed which slag contains excess of lime and iron oxides
substantially as and for the purposes set forth.
1
20 1
1000
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London,
Applicant's Agent.