Year: 1887

page_text: Date of Application, 23rd May, 1887
Complete Left, 23rd Feb., 1888
Complete Accepted, 23rd Mar., 1888
I, PERCY CARLYLE GILCHRIST of 9 Bridge Street in the City of Westminster,
Metallurgist, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the conversion of crude pig iron into
ingot iron or steel in basic lined open hearth furnaces by means of phosphoric
or other impure ores of iron. Hitherto in working the basic process in open hearth
furnaces it has been the custom to add the ore and the bulk of the lime or limestone
after the charge is melted. When working with an acid lined furnace it is not
practicable to add any ore when charging the pig iron, owing to the strong action of
the ore on the silicious lining, and a charge composed wholly of pig iron without any
scrap is not economical owing to the time required for its purification besides which
pure non-phosphoric hoematite ores can alone be used in silicious lined furnaces, and
the greater part of the ore added is found in the slag as ferrous silicate, and these
requirements of acid open hearth practice have hitherto been generally adhered to in
basic working in the open hearth furnace. I have found however that the method of
working can be conveniently and economically modified and the process considerably
shortened over the time required to purify a charge of hoematite pig iron in an
ordinary acid lined furnace by carrying out the purifying operation in the following
manner. The charge of metal to be purified is composed only of pig iron except
when there is scrap iron to be used up when the charge can be composed as usual of
scrap and pig iron, but 1 find it most economical to work pig only in the basic
furnace.
The basic lined furnace having been prepared for charging in the ordinary way I
introduce into it the charge composed of pig iron, ore, and limestone or lime. Instead
of restricting the amount of ore used as much as possible I purposely use as large a
quantity of it as can possibly be reduced by the metalloids of the pig iron used.
The ore to be used is not confined as in the acid practice to pure hoematite ores
but nearly any rich iron ore which is not too silicious may be employed; it should
not however be very high in sulphur, but may be phosphoric. Calcareous or
aluminous ores may be conveniently employed, mill or hammer scale or rich
ferruginous slags low in silica can also be used. I prefer to use an ore in which the
greater part of the oxide of iron exists in the ferrous state as the purification of the

page_text: charge is thereby considerably accelerated. If the ore employed contains much
organic matter or moisture it may be roasted before use.
The lime or limestone and the ore having been crushed to the size of gravel and
previously intimately mixed, are spread over the hearth and banks of the furnace and
allowed to get thoroughly hot before the pig iron.is charged; part of the ore and
limestone may also be charged with the pig iron partly among and partly on top of it,
but care must be taken not to charge the ore and lime so thickly amongst the pig iron
as to hinder its melting. About 5 cwt. of lime and 6 cwt. of ore may be used
per ton of pig iron when a pig is used containing some 3% phosphorus and 1%
silicon.
The charge being melted a sample should be taken at once, it is often almost
completely purified, at other times it boils for an hour or two after melting and
sometimes more ore and lime must be added before the necessary purification is
obtained; the aim of the melter should be to very nearly remove all the carbon and
and phosphorus in the metal during the time of melting down.
It will be found that by the method described a larger yield of metallic iron will
be obtained than if the ore were thrown into the furnace after the pig iron was melted
and the operation will also be considerably accelerated.
When the bath of metal is ready it is tapped in the usual way and the requisite
amount of ferro manganese, ferro silicon or spiegel added in the ladle; it is well to
throw it into the bath just before tapping one or two pieces of pig iron to liven
the metal up and give it a slight boil; the metal is usually extremely soft and there is
no difficulty in getting rid of the phosphorus, simultaneously with or prior to the
removal of the carbon. The greater part of the ore added will have been reduced
to the metallic state by means of the carbon, phosphorus and silicon in the pig iron;
the slag should not contain much above ten per cent. of iron, the silicon and
phosphorus existing in the slag as silicate and phosphate of lime.
Dated this 23rd day of May 1887
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London,
Applicant's Agent.

page_text: Improvements in the Manufacture of Iron and Steel.
I, PERCY CARLYLE GILCHRIST of 9 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 :-
This invention relates to improvements in the conversion of crude pig iron into
ingot iron or steel in open hearth furnaces having a basic lining by means of
phosphoric or other impure ores of iron and is especially adapted for use in countries
where the iron industry is not fully developed.
When working with an acid lined furnace it is not practicable to add any ore when
charging the pig iron, owing to the strong action of the ore on the silicious lining.
In acid working therefore a charge composed wholly of pig iron without any scrap
is not economical owing to the time required for its purification, pure non-phosphoric
hematite ores only are used in a silicious lined furnace and then the greater part
of the ore added is found in the slag as ferrous silicate.
Hitherto in working the basic process in open hearth furnaces it has been the
custom to pursue practically the method of working used when the furnace is lined
with an acid lining, modifying the process only so far as the conditions of basic
working require. I have found however that the basic method of working can be
conveniently and economically modified and the process considerably shortened over
the time required to purify a charge of hematite pig iron in an ordinary acid lined
furnace by carrying out the operation in the following manner :-The furnace
in which the operation is to be performed may be either an ordinary open hearth
Siemens furnace or may be an open hearth furnace of the type known as the Batho
furnace, that is, having separate regenerators and being provided with Hackney ports.
Whatever form of furnace is used the hearth is always composed of basic or neutral
material, that is, either dolomitic lime, magnesia, chrome-iron ore or bauxite or
suitable mixtures of these bodies. If dolomite or magnesite be used as the basic
material to forin the hearth they must have been previously shrunk by being
subjected to a very high temperature. The best method of making the hearth
is to form it of bricks made of shrunk basic material mixed with a little tar and
subjected to considerable pressure.
The sides and banks of the furnace for the height of about eighteen inches above
the level to which the bath will reach to should also be built of basic bricks, a
thickness of lining of from eighteen inches to two feet being necessary at the level of

page_text: the bath. The sidewalls and ports above these basic bricks may be built of the best
silica bricks, these silica bricks must not be allowed to rest on the basic bricks but
may be supported on a strong angle-iron fastened to the plates of the furnace body.
When a dolomitic lining is used it is often convenient to interpose a layer of
non-silicious chrome-iron ore or other neutral body between the basic and silica
bricks instead of using an angle iron. The chrome-ore is very conveniently used by
being previously formed into bricks by mixing the crushed ore with a small quantity
of milk of lime just sufficient to moisten the mass, pressing the mixture into moulds
and firing the bricks before using them in the furnace. The basic material used for
the hearth and sides instead of being used in the form of bricks may be mixed with
sufficient tar to make it just adhere and be then rammed into position with hot rammers.
The roof is composed entirely of silica bricks and may conveniently be supported in
a strong iron ring, the weight of the whole being taken by the iron plates and
buckstays of the furnace and not by the brick lining. The furnace being lined
as above, heat is got up in the furnace in the usual way and the charge introduced.
The charge of metal to be purified may advantageously be composed of phosphoric
pig iron only except when there is scrap iron to be used up when the charge can be
composed as usual of scrap and pig but I find it most economical to work pig only in
the basic furnace.
The basic-lined furnace having been prepared for charging in the ordinary way
I introduce into it the charge composed of pig, ore, and limestone or lime. Instead
of restricting the amount of ore used as much as possible I purposely use as large a
quantity of it as can possibly be reduced by the metalloids of the pig-iron used.
The ore to be used is not confined as in acid practice to pure hematite ores, but
nearly any rich iron ore which is not too silicious may be employed, it should not
however be very high in sulphur but may be phosphoric. Calcareous or aluminous
ores may be conveniently employed, mill or hammer scale or rich ferruginous slags,
low in silica, can also be used. I prefer to use an ore in which the greater part
of the oxide of iron exists in the ferrous state as the purification of the charge
is thereby considerably accelerated. If the ore employed contains much organic
matter or moisture it may be roasted before use.
If the pig iron to be purified, or if the iron ore used be at all high in sulphur
I always prefer to add when charging, a certain amount of an ore rich in manganese,
thus if a rich manganese ore be obtainable, about half a hundred weight of it may
be charged per ton of pig iron charged, even more than this may be used in cases
where ferro manganese is very expensive the final additions of ferro manganese being
at the same time diminished, as the bath of metal will be found to contain a certain
percentage of manganese due to a partial reduction of the manganese ore added.
The lime or limestone and ore having been crushed to the size of gravel, are spread
over the hearth and banks of the furnace and allowed to get thoroughly hot before the
pig is charged. About 5 cwt. of lime and 6 cwt. of ore may be used per ton of pig
iron when a pig is used containing some 3 % phosphorus and 14% silicon.
The charge being melted a sample should be taken at once as it will often be almost
completely purified, at other times it boils for an hour or two after melting and
generally more ore and lime must be added before the necessary purification is
obtained, the aim of the melter should be to very nearly remove all the carbon and
phosphorus in the metal during the time of melting down and to, remove the
phosphorus before all the carbon. When the bath of metal is ready it is tapped
in the usual way and the requisite amount of ferro manganese is added in the ladle,
it is well to throw into the bath just before tapping one or two pieces of pig to liven
the metal up and give it a slight boil. The metal is usually extremely soft and there
is no difficulty in getting rid of the phosphorus simultaneously with or prior to the
removal of the carbon. The greater part of the ore added will have been reduced to
the metallic state by means of the carbon, phosphorus and silicon of the pig iron; the
slag should not contain above 10% of iron, the silicon and phosphorus existing in
the slag as silicate and phosphate of lime.

page_text: 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 herein before described process of treating phosphoric pig iron and converting
it into iron or steel in a basic lined open hearth furnace which consists in adding with
the charge of pig iron as much lime or limestone as can possibly be used consistently
with keeping a fluid slag and from 7 to 8 times as much iron ore or oxide (which may
be phosphoric) as there is phosphorus and silicon in the pig for the purpose of
effecting the greater part of the purification of the pig iron as it melts in the furnace
substantially as set forth.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, .
Agent for the Applicant.