Improvements in Cleaning and Annealing Iron and Steel, and Apparatus therefor.
Year: 1890

page_text: Date of Application, 25th Jan., 1890
Complete Specification Left, 25th Oct., 1890-Accepted, 25th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Cleaning and Annealing Iron and Steel, and
Apparatus therefor.
I, GUY CAREY FRICKER, of No. 39, Montserrat Road, Putney, in the County
of Surrey, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
This invention has reference particularly to cleaning and annealing sheets, wire
or other bodies of iron or steel preparatory to tinning or galvanising the same.
Up to the present time the common method of preparing iron sheets and wire
for tinning or galvanising has been to first immerse them in a strongly acid bath
with the application of heat until the black scale or oxide is entirely removed from
the surface. After this process of pickling, sheets destined for tinning are put into
the annealing oven in a closed iron box and there subjected to a red heat for some
hours. After a gradual cooling the sheets are cold rolled whereby a smooth surface
is produced, but the sheets are at the same time rendered hard and springy. In
order to reduce them again to a soft and ductile condition the annealing process is
repeated, after which the slight film of oxide which forms in the annealing oven is
removed by a second pickling operation before the final process of tinning. The
two operations of pickling are attended by great waste both of acid and iron,
furthermore the chemical product which is formed, viz., ferrous sulphate or chloride
is very troublesome to reduce to a marketable state and even then does not
command a price which repays the cost of its production from the waste pickling
liquids. The consequence is that canals and rivers are polluted with these waste
liquors to a very large extent. Furthermore during the pickling process dense
fumes are given off which are most injurious to those engaged in the work, and in
all respects the present method of preparing iron sheets and wire for tinning or
galvanising is a costly, unhealthy and very unsatisfactory one.
In place of the foregoing processes it has been proposed to utilize the known
properties of hydrogen gas and other similar gascous reducing agents to convert
the scale or oxide on iron surfaces to the metallic state whilst at an elevated
temperature. The practical commercial success of such a process must depend
upon means for securing economy in the consumption of the reducing material used,
and upon simplicity in the form of the apparatus. Hitherto no means for securing
these objects have been made known and consequently, so far as I know, the before
mentioned proposal has not been practically and successfully carried out.
My invention consists of improved means of applying hydrogen gas or other
suitable gaseous reducing agents, such as common coal gas or sulphuretted
hydrogen, for the purposes above mentioned; preferably I use hydrogen. One
of my principal objects is to provide means whereby the useless consumption or
vaste of the reducing agent is avoided. In order to effect this object the hydrogen
s caused to pass into the annealing or reducing chamber or chambers where it
nites with the oxygen on the iron under treatment and forms steam. The mixture
of steam and unconsumed gas then passes into a pipe or set of pipes forming a
urface condenser or into an ejection condensing chamber. The outlet of this
ondenser dips into water which forms a water seal to prevent the escape of gas,
hile allowing of the escape of the water of condensation. This condensation of
team tends to produce a vacuum in the portion of pace in which it occurs, and
resh hydrogen is consequently drawn into the reducing chamber from the source
f supply.
This formation and condensation of steam goes on causing a currert of hydrogen

page_text: to pass into the reducing chamber until no more scale or oxide remains on the
surface of the iron bodies; and when this condition is attained, the current ceases
and an atmosphere of hydrogen remains in the annealing boxes or reducing
chambers. The sheets or other iron bodies may remain thus at an elevated tempe-
rature in the atmosphere of hydrogen as long as is desirable for the purposes of
annealing, without re-oxidation. This atmosphere is maintained in the reducing
chamber when the said chamber is withdrawn from the furnace and until the sheets
or other iron bodies therein are sufficiently cool to be removed without fear of
further scaling. On removal they are found to present a clean and silvery
appearance and to be in a fit state to receive an adherent coating of tin or zinc by
dipping in the ordinary way. The absolutely clean surface which is produced by
my process renders it also possible to obtain much better results from the electro-
lytic deposition of metals upon iron, than are at present attainable. In tin plate
works where the sheets have to be cold rolled and a second annealing is necessary,
the reducing process is repeated after the operation of cold rolling.
It is sometimes convenient to produce a more rapid current of hydrogen through
the reducing chamber than is induced by the above described condensing arrange-
ment.
In such cases I make use of an additional external mechanical arrangement
for effecting a circulation of hydrogen, as follows:-
The gas receiver which whether in this or in the former case consists preferably
of an ordinary gasholder sealed by water in the usual way, is connected to the
reducing chamber by a delivery pipe and hy a return pipe, and I interpose in the
path of the gaseous reducing agent an air pump, fan or blower; a suitable position
for which is in connection with the delivery pipe between the receiver and the
reducing chamber. In this position the pump, fan or blower, propels the gaseous
reducing agent into the reducing chamber where a portion of it forms steam, which
admixed with the unconsumed hydrogen is forced out of the reducing chamber
through the return pipe and condenses on its way into the receiver, the unconsumed
hydrogen being delivered thereinto in an unchanged condition. A special con-
densing arrangement may be fitted to the receiver, but it is usually sufficient to pass
the unconsumed hydrogen through the water seal of the receiver, the steam being
condensed and arrested. The fan may, however, be placed in any other part of
the circulating system, its purpose being to increase the current of gas beyond that
which would be induced by the condensation method alone and at the same time
without causing any waste of gas.
I do not contine myself to the above described methods of causing a current of
fresh hydrogen to pass over the surface of the iron bodies under treatment and for
the recovery of the unconsumed portions of the same. Other methods whereby this
may be effected may be devised without departing from my invention; for example,
two receivers may be used, with the reducing chambers connected between them.
By alternately raising and lowering the receivers or gasholders the one can be
emptied through the reducing chamber into the other and vice vers 1.
By this
means a to-and-fro current of the gaseous reducing agent is maintained through the
reducing chamber whilst the unconsumed portions are continually recovered. The
arrangement of the annealing oven or furnace and of the reducing chambers is
important. In carrying out my invention I prefer to arrange these in the following
way.
Each annealing box or reducing chamber consists of a gas-tight refractory
elongated chamber or box, preferably of iron or steel. This box is usually rect-
angular in cross section and permanently closed at one end. A partition running
longitudinally from the mouth of the chamber nearly to the closed end thereof,
divides the same into two equal portions; so that gas being admitted at the mouth
on the one side will pass down the length of the chamber on that side of the par-
tition, and return up the other side. The sheets or other iron bodies to be treated
are inserted in the two divisions of the box in such a way as to allow a free passage
of the gas over their surfaces. The box or chamber is passed into the annealing

page_text: oven or furnace through an aperture in the same, which may be closed in the
ordinary manner by a door when the box is not in position. The box may be so
formed that its open end projects somewhat from the furnace. When in position in
the furnace the front end of the box, which may be flanged for the purpose, suffices
to close the aperture in the side of the furnace. After placing the articles which
are to be treated in the box, its mouth is closed by a well fitting door or lid, which
abuts against the middle partition and which is luted on. The pipe for the delivery
of the gas is fitted at the mouth of the box on one side of the partition; the
exhaust or return pipe being fitted at the mouth on the other side of the partition.
A number of reducing chambers may be so arranged in one furnace and fed with
hydrogen from one main pipe. In each branch pipe to the several chambers cocks
may be arranged so that the supply of gas may be regulated or stopped. The
necessary hydrogen gas may be produced in any well known way, and
generate it by passing steam through iron clippings, borings or scrap contained in a
set of tubes or retorts heated to redness in the ordinary way. The iron scrap may
be readily supplied in a tin-plate works from the clippings of the rough sheets.
Dated this with day of January 1800
prefer to
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Cleaning and Annealing Iron and Steel, and
Apparatus therefor.
I, GUY CAREY FRICKER, of 39, Montserrat Road, Putney, in the County of
Surrey, Electrical Engineer, do hereby declare the nature of this invention, and
in what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
This invention has reference to the cleaning and annealing of sheets, wire or
other bodies of iron or steel preparatory to tinning or galvanising the same.
Hitherto the common method of preparing iron or steel sheets and wire for tinning
or galvanising has been to first immerse them in a strongly acid bath with the
application of heat until the black scale or oxide is entirely removed from the sur-
face. After this process of pickling, sheets destined for tinning are put into an
annealing oven in a closed iron box and there subjected to a red heat for some
hours. After a gradual cooling the sheets are cold rolled whereby a smooth surface
is produced, but the sheets are at the same time rendered hard and springy. In
order to reduce them again to a soft and ductile condition the annealing process is
repeated, after which the slight film of oxide which forms in the annealing oven is
removed by a second pickling operation before the final process of tinning. The
two operations of pickling are attended by great waste both of acid and iron,
furthermore the chemical product which is formed, riz. ferrous sulphate or chloride,
is very troublesome to reduce to a marketable state, and even then does not com-
mand a price which repays the cost of its recovery from the waste pickling liquids.
The consequence is that canals and rivers are polluted with the waste liquors to a
very large extent.
Furthermore during the pickling process dense fumes are given
off which are most injurious to those engaged in the work, and in all respects the
present method of preparing iron sheets and wire for tinning or galvanising is a
costly, unhealthy, and very unsatisfactory one.
Now the object of my invention is to obviate the above mentioned evils and to
cheapen the process of cleaning and annealing the iron or steel to which end it con-
sists in reducing the oxide or scale on the iron or steel surfaces by means of
hydrogen gas at an elevated temperature, and removing and condensing the steam

page_text: formed in the process of reduction without allowing the escape of unconsumed
hydrogen and so as to prevent reoxidation during cooling of the iron or steel treated.
In carrying out my invention I employ an apparatus comprising a reducing or
annealing chamber in combination with means for generating and feeding hydrogen
or other similar gaseous reducing agent containing hydrogen, such as common coal
gas or sulphuretted hydrogen, thereto, and a condenser in communication or con-
nection with the reducing or annealing chamber, for the purpose of causing the
gaseous reducing agent to act upon the oxide on the surfaces of the iron or steel
under treatment in said reducing chamber and for condensing the steam formed in
the process of reduction, without allowing the escape of unconsumed portions of said
gaseous reducing agent and so as to prevent re-oxidation, during cooling, of the
iron or steel treated as above set forth.
And in order that my invention may be fully understood I will proceed to
explain the same more in detail and by reference to the accompanying drawings
which illustrate the best means known to me for carrying the same into practical
effect.
Referring to these drawings,
Fig. 1 illustrates one method of applying hydrogen according to my invention.
From the generator a hydrogen is caused to pass into the receiver or gasholder B
(hereinafter called a gasholder) from whence it is conveyed by the pipe C, which
is preferably flexible between the points and g, into the reducing and annealing
box or chamber F, (hereinafter generally referred to as a box) which is inserted
as shewn in Fig. 1 in the annealing furnace I wherein the annealing and reducing
box F and its contents are raised to nearly a white heat. When this temperature
is attained the hydrogen unites with the oxygen on the iron under treatment and
forms steam. The reducing and annealing box is connected with a condenser of
any suitable form, into which the steam passes and is therein condensed. One form
of condenser is shewn in cross section in Fig. 1 at G, and in plan in Fig. 14.
In Fig. 1 the outlet of this condenser is shewn as dipping to a suitable depth into
water at H whereby a water seal is formed having a suitable pressure for the
purpose of preventing the escape of gas while the escape of the water of
condensation is permitted. This condensation of steam in the condenser tends to
produce a vacuum and a current of fresh hydrogen is continually drawn into the
Lox from the source of supply, until all the scale or oxide on the surfaces of the
iron bodies is reduced, the iron which was in combination in the oxide being deposited
on the surfaces of the wire or sheets as a thin adherent layer of pure iron. When
this condition is attained, the current ceases and an atmosphere of hydrogen
remains in the reducing and annealing box or boxes. The sheets or other iron
bodies may remain thus at an elevated temperature without re-oxidation in the
atmosphere of hydrogen as long as is desirable for the purposes of annealing.
This atmosphere is maintained in the reducing and annealing box when the said
box is withdrawn from the furnace and until the sheets or other iron bodies
therein are sufficiently cool to be removed without fear of further scaling. On
removal they are found to present a clean and silvery appearance, and to be in a fit
state to receive an adherent coating of tin or zinc by dipping in the ordinary way.
Another form of condenser is shewn in Fig. 1B comprising a condensing vessel V
contained in an outer vessel V' containing water which is maintained at a low
temperature by circulation or otherwise. The vessel V is provided with a pipe
leading to the reducing box. It is also provided with a drain-cock C', by which at
intervals the water of condensation may be discharged. By this condensing
process I not only avoid the waste of hydrogen, but I remove from the reducing
box the steam which is formed by the reduction of the iron oxide and which if
allowed to remain in the box would during the process of cooling, re-oxidise
the plates. According to another arrangement when the process is only required
to take place slowly a special condenser is dispensed with and the gasholder is
made to act both as a gasholder and as a condenser. This arrangement is shewn in
*

page_text: Fig. 2.
The gasholder B in this case comprises an ordinary arrangement of a
vessel inverted in water, and open at the lower end the water preventing the escape
of the gas. The tube C opens above the water in the gasholder B and hydrogen
is free to pass through the tube into the reducing box. At the same time any
steam formed in the reducing box F is free to pass by diffusion into the tube C and
so into the gasholder B where it is condensed in the cooler atmosphere. I some-
times provide means for maintaining the water in the gasholder at a low
temperature in order to facilitate this condensing action, and I may use a water
spray within the gasholder for this purpose. Thus it will be seen that when I
carry out my invention in this manner, the gasholder with water seal is made to act
in the double capacity of gas receiver or holder and condenser.
In tin plate works where the sheets have to be cold rolled and a second annealing
is necessary, the reducing process is or may be repeated after the operation of cold
rolling thus avoiding the necessity for the less important but still objectionable acid
process known as "white pickling."
It is sometimes convenient to produce a more rapid current of hydrogen through
the reducing box than is induced by the above described condensing arrangements.
In such cases I sometimes supplement the action of the condenser by imparting to
the stream of gas which it induces, a more rapid motion by means of a pump, fan
or blower.
Fig. 3 illustrates this modified arrangement. The gasholder B which in both
this and in the former cases consists preferably of an ordinary gasholder sealed by
water in the usual way, is connected with the reducing box F by a delivery pipe C and
by a return pipe D, and I interpose in the path of the gaseous reducing agent a
pump, fan or blower E such as that known as the Root's blower, or of other
suitable construction. A suitable position for this pump, fan or blower is in
connection with the delivery pipe between the gasholder and the reducing box, as
shewn at E in Fig. 3. In this position the blower propels the gaseous reducing
agent into the reducing box where a portion of it forms steam, which, admixed
with the unconsumed hydrogen is forced out of the reducing chamber through the
return pipe D and condenses on passing into the water seal of the gasholder B, at
the outlet D', the unconsumed hydrogen being delivered into the gasholder B in an
unchanged condition. A special condensing arrangement may be fitted to the gas-
holder, but it is usually sufficient to pass the unconsumed hydrogen through the
water seal of the receiver as shewn in Fig. 3. The pump, fan, or blower E may,
however, be placed in any other part of the circulating system, its purpose being to
increase the current of gas beyond that which would be induced by the condensation
method alone and at the same time without permitting any waste of
gas.
Another manner of carrying out my invention of causing a current of fresh
hydrogen to pass over the surfaces of the iron or steel bodies under treatment and of
recovering the unconsumed portions of the hydrogen and of preventing reoxidation
is as shewn in Fig. 4 where two gasholders B B are used with the reducing box or
boxes F connected between them. By alternately raising one gasholder and lowering
he other gasholder, the one can be emptied through the reducing box into the other
nd rice versa. By this means a to-and-fro current of the gaseous reducing agent is
naintained through the reducing box whilst the unconsumed portions are continually
ecovered, the steam formed in the reducing process being condensed in the water
eal of the gasholder which is acting as a receiver. The arrangement of the
nnealing oven or furnace and of the reducing boxes is important. In carrying
ut my invention 1 prefer to arrange them in the following way.
Each annealing box or reducing chamber consists of a gas-tight refractory
longated chamber or box, preferably of iron or steel. This box is usually
ectangular in cross section and permanently closed at one end.
Fig. 5 is a longitudinal section and Fig. 6 a front elevation of the box shewu
losed.
Fig. 7 is also a front elevation but with the door removed.

page_text: The partition P running longitudinally from the mouth of the chamber to the
point (Fig. 5) situated nearly at the closed end thereof, serves as a support to
the upper side of the box and divides the same into two equal compartments p³ p²;
so that gas being admitted at the mouth on the one side will pass along the
length of the chamber on that side of the partition, and return along the other
side.
may
In Fig. 8 a section is given shewing three boxes F F F in place in the furnace I
and illustrating how the iron sheets F' are or may be inserted in the boxes. The
boxes are passed into the annealing oven or furnace through apertures in the front
side thereof which may be closed in the ordinary manner by doors when the boxes
are not in position. This arrangement is shewn in transverse section in Fig. 1 and
in front elevation in Fig. 9 which is a front elevation of the furnace and boxes
shewn in Fig. 8. Each box may be so formed that its open end projects somewhat
from the furnace as seen in Fig. 1. When in position in the furnace, the front end
of the box which may be flanged as shewn in Fig. 5 for the purpose, suffices to
close the aperture in the side of the furnace. After placing the articles to be
treated, in the box, its mouth is closed by a well fitting door or lid as shewn at d³,
Fig. 5 which abuts against the middle partition and is luted on. The pipe for the
delivery of the gas is fitted at the mouth of the box on one side of the partition;
the exhaust or return pipe is fitted at the mouth on the other side of the partition.
These pipes may conveniently be carried by the door or lid of the box as shewn
at Fig. 6. A number of reducing boxes may be so arranged in one furnace
and fed with hydrogen from one main pipe e as shewn in Fig. 9. In each branch
pipe to the several chambers the cocks c c c² may be arranged so that the
supply of gas may be regulated or stopped. Cocks as shewn at ffff Fig. 9
also be inserted in the return branch pipes so that when the reduction of scale is
complete both cocks may be closed and the box removed from the furnace and the
articles contained therein allowed to cool in an atmosphere of hydrogen. It is
however preferable to keep the supply pipe open during the period of cooling so
that no air is drawn in as the gas within the box contracts. My usual practice is
therefore as follows:-After the reducing box containing the articles under treat-
ment has been maintained at a nearly white heat and supplied with hydrogen in the
manner described until the reduction of scale is complete, both the supply and
return pipes are closed by the cocks c and Fig. 1 attached thereto; the duplicate
cocks in the supply pipe as shewn at 7 and that in the return pipe as shown at k
Fig. 1 are also closed and the union joints u u¹ between the cocks g and c and
between k and fare parted. The box being filled with an atmosphere of hydrogen
is then removed from the furnace. After removal the flexible supply pipe Cis
again connected by the union u to the box in any convenient position and the
cocks g and e Fig. 1 are re-opened; the cock in the return pipe however is kept
closed. When the box is sufficiently cool to prevent the iron sheets therein being
oxidised by exposure to the air, the cock y from the supply pipe is closed and the
box is disconnected and the lid may be removed. When the sheets however are
not required to be immediately tinned or galvanised, I keep the lid on and the
cocks and closed; the sheets then remain in a cool atmosphere of hydrogen and
may be kept without reoxidation for an indefinite period.
C
The necessary hydrogen gas may be produced in any well known way, and I
prefer to generate it by passing steam over iron clippings, filings, borings, or scrap
contained in a tube or set of tubes or retorts heated to redness in the ordinary way
as indicated at A. Fig. 1. The iron scrap may be readily supplied in a tin plate
works from the clippings of the rough sheets.
The absolutely clean surface which is produced by my process renders it also
possible to obtain much better results from the electrolytic deposition of metals
upon iron and steel than are at present attainable.
I am well aware that it has been proposed to utilise the known properties of
hydrogen gas and other similar gascous reducing agents to convert the scale or

page_text: oxide on iron surfaces to the metallic state whilst at an elevated temperature, but
so far as I know no means have been devised prior to my invention whereby such a
process could be carried out practically on a commercial scale. Now my invention
by preventing useless consumption or waste of the reducing agent and by ensuring
the removal of the products of reduction from the reducing chamber, and by
preventing reoxidation during cooling of the iron or steel treated makes it not only
possible but highly advantageous to carry on commercially manufacturing processes.
with gaseous reducing agents for the purposes specified.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The herein described process of cleaning and annealing iron or steel by
reducing the oxide or scale on the iron or steel surfaces by means of hydrogen or
other gas such as hereinbefore referred to at an elevated temperature, removing and
condensing the steam formed in the process of reduction, and preventing escape of
unconsumed hydrogen and re-oxidation during cooling of the iron or steel treated
substantially as hereinbefore described.
2. For cleaning and annealing iron or steel according to the process referred to
in the preceding claim the combination of a reducing and annealing chamber, means
for feeding thereto hydrogen or other gaseous reducing agent such as referred to,
and a condenser in connection with the reducing and annealing chamber, the
arrangement being such that the gascous reducing agent will be caused to act upon
and reduce the oxide on the surfaces of the iron or steel under treatment in the
reducing chamber, and the steam formed in the process of reduction will be
condensed without allowing the escape of unconsumed portions of the gaseous
reducing agent.
3. The construction and use for cleaning and annealing iron or steel in the
manner set forth of apparatus such as referred to in Claim 2 with means for causing
the circulation of a current of hydrogen or other gaseous reducing agent through
the reducing and annealing chamber thereby removing the products of the
reduction, causing condensation of those products and preventing waste of the
gaseous reducing agent as hereinbefore described with reference to Fig. 3 of
the drawings.
4. In an apparatus for cleaning and annealing iron or steel by means of a gaseous
reducing agent such as hereinbefore referred to, the combination with a reducing
or annealing chamber or chambers, of two or more gas holders or receivers and
suitable connections the arrangement being such that one or some of the said gas-
holders or receivers may be emptying its or their contents through the reducing or
annealing chamber or chambers into the remaining gas holder or receiver, or holders
or receivers, and vice versa, thereby producing a to and fro current of the gaseous
reducing agent through the reducing or annealing chamber or chambers and causing
the steam produced by the reduction to be removed without permitting the escape
of unconsumed portions of the gaseous reducing agent.
5. The construction and use of an apparatus for cleaning and annealing iron or
steel by means of a gaseous reducing agent such as herein before referred to with a
box or reducing and annealing chamber made of refractory material with a mouth,
a closed end and a partition such as P running from the mouth nearly to the closed
end, a gas tight door or lid, a supply pipe and a return pipe at or near the lid, one
of these pipes opening into the box on one side of the partition, and the other pipe
opening into the box on the other side of the partition whereby the gaseous reducing
agent entering by the supply pipe is caused to pass through one side of the box and
to act upon all the iron or steel surfaces contained in that side and afterwards to
pass through the other side of the box and act upon all the iron surfaces therein
contained substantially as hereinbefore described with reference to and shewn in
Figs. 5, 6 and 7 of the annexed drawings.

page_text: 6. The several constructions of apparatus of the kind referred to for cleaning
and annealing iron & steel as set forth, hereinbefore described with reference
respectively to and shewn in Figs. 1 and 14 (or modified according to Fig. 1º);
Fig. 2 Fig. 3; and Fig. 4 of the drawings annexed.
Dated this 25th day of October 1890.
W. Lloyd Wise,
G. C. FRICKER.
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.