IMPROVEMENTS IN THE MEANS AND APPARATUS FOR GALVANIZING IRON, OR COATING IT WITH ZINC AND TIN
Year: 1877

page_text: LETTERS PATENT to Frederick Braby, of No. 358, Euston Road, in the County
of Middlesex. Galvanized Iron Manufacturer, and Arthur Charles Moore, of
Ida Wharf, Deptford, in the County of Kent, Galvanised Iron Manufacturer,
for the Invention of "IMPROVEMENTS IN THE MEANS AND APPARATUS FOR
GALVANIZING IRON, OR COATING IT WITH ZINC AND TIN."
Sealed the 28th August 1877, and dated the 29th June 1877.
PROVISIONAL SPECIFICATION left by the said Frederick Braby and Arthur
Charles Moore at the Office of the Commissioners of Patents on the 29th June.
1877.
FREDERICK BRABY, of No. 358, Euston Road, in the County of Middlesex,
Galvanised Iron Manufacturer, and ARTHUR CHARLES MOORE, of Ida Wharf,
Deptford, in the County of Kent, Galvanised Iron Manufacturer. "IMPROVEMENTS
IN THE MEANS AND APPARATUS FOR GALVANISING IRON, OR COATING IT WITH ZINC
AND TIN."
In galvanising sheet iron, netting, or other extended surfaces, these are immersed
into a bath of molten zinc at one side thereof and pass out of the bath at the other
side. The zinc bath requires to have a layer of muriate of ammonia or other
deoxidiser upon its surface, in order to prevent the molten zinc from oxidising on
the surface through contact with the air, and also to cleanse the surface of the iron
before it passes into the zinc. The muriate of ammonia has itself, however, an
injurious effect upon the coated or galvanised iron as it emerges from the bath,
discolouring the coating of zinc thereon.
One part of our present Invention has for its object to avoid this injurious effect,
and it consists in providing at the delivery or exit side of the bath a narrow space
which is kept clear of flux, through which space the sheet is made to pass as it
issues from the bath. This space may be formed between two partitions that dip
down into the molten metal; but as the portion of the surface of the metal lying
between these partitions would, if it remained quiescent, be subject to oxidation,
we keep the fluid metal in motion between the partitions so as always to change
the surface thereof,. and we effect this by making these partitions in the form of

page_text: rollers, which are partially immersed in the metal and are kept revolving in
opposite directions, that is to say, the sides facing each other are always ascending
whilst the opposite sides descend. These rollers, besides separating the flux on either
side from the space between them, act also as continuous skimmers, continually
changing and keeping clean the surface through which the galvanised sheet issues,
and such portions of the zinc as may adhere to them and become oxidised on the
exposed portions of their periphery become again deoxidised by being carried
through the flux on their outer descending sides.
The revolving skimmers are placed sufficiently far apart to permit the sheets to
issue from between them without touching them, the sheets being guided in the
proper direction by rollers or guides below the surface of the molten metal or by
hooked rods worked by hand.
Instead of two revolving skimmers, as above described, a single skimmer may be
employed at the one side of the delivery space, a fixed plate or partition which may
be the end of the bath forming the other side; but as in that case portions of zinc
might become deposited on the fixed partition, and remain stationary there, so as to
become oxidised, we prefer to employ the two skimmers, both sides of the spaco
being thus kept clean by their revolution.
In order to economise muriate of ammonia it may be confined to a small space
immediately at the back of each revolving skimmer by means of metal plates
arranged parallel with the revolving skimmers at a certain distance therefrom and
dipping into the molten zinc, or nearly so; and if desired such plates may have
hoods attached thereto, covering in the layers of flux so as to enclose the fumes
arising therefrom, spouts closed by covers being provided in such hoods through
which fresh flux may be introduced when required, and openings or tubes for
leading away the fumes evaporated therefrom to condensers or elsewhere. The
other part of the surface of the zinc bath beyond the delivery side may be covered
with a layer of spent muriate of ammonia, with aluminium, or with any other
suitable material that will float on aud cover the molten zinc, protecting it from
contact with the atmosphere without.being itself.acted upon by the molten metal.
For some classes of work the flux on the delivery side of the bath may be dis-
pensed with, the sheet being to caused to issue through a narrow space between
partitions or revolving skimmers dipping into the molten metal, as above described.
Another part of our Invention has for its object to obviate the inconvenience and
loss that now arises from the evaporation of the volatile constituents from the
layer of muriate of ammonia, covering the molten zinc of the bath on the receiving
or entrance side thereof, such vapours, as also the gaseous products of combustion
from the incandescent fuel at the side of the bath, being at present allowed to
escape free into the workshop, occasioning a loss of material and also considerable
inconvenience to the operatives.
According to one modification of our Invention we enclose the receiving side of
the zinc bath by a hood or cover, having a lip that dips down into the molten metal
of the bath at or about the middle thereof, thus completely separating the receiving
from the delivery side thereof, and extends from that point either to the side of the
bath, if it is desired only to confine the vapours thereof, or to the brickwork
enclosure beyond the fuel at the side of the bath, if it be desired also to confine the
gases rising from the fuel. Or separate covers or enclosures may be made to
convey the products of combustion of the fuel into the hood over the receiving side
of the bath.
At a short distance above the top of the bath we provide in the hood a long
narrow opening or slit through which the sheet to be galvanised is inserted, such
openings having by preference on the one edge a strip of elastic or yielding packing
material, such as vulcanised caoutchouc, while the other edge is formed by a
hinged plate pressed against the packing by a weight or spring, so that when no
sheet is being passed through, the opening is closed against the escape of vapour or
gases The inner surface of the hood is made of any suitable material that will
not be quickly destroyed by the muriate of ammonia fumes and other gases, and

page_text: the former may either be allowed to condense inside the hood and fall back on to
the bath, or the fumes and gases may be conducted from the hood through a pipe
to a condenser or elsewhere. The gases arising from the burning fuel, being mainly
carbonic anhydride, carbonic oxide, and nitrogen, will not seriously injure the
muriate of ammonia or the iron or zinc, and the heat thereof will tend to dry the
metal sheets (which are wet from the pickling bath), and also warm them before
they pass into the zinc bath, the steam thus generated mixing with the other gases
and being conducted away with them.
The closed end surfaces of the hood may be provided with doors, through which,
when required, the spent muriate of ammonia may be removed, and fresh muriato
may be introduced by those doors or by covered spouts provided at the front of the
hood.
The hood may have one or more openings covered by loaded flaps to act as safety
valves for allowing the escape of gases should the pressure thereof rise unduly, and
similar valves or flaps may be provided in the escape pipe before mentioned, such
valves being by preference rather more lightly loaded than those on the hood.
For the purpose of guiding the sheet iron in the proper direction as it enters the
bath three rollers may be provided, two being either above the layer of flux, or, by
preference, partially immersed in the bath with a space between them covered with
muriate of ammonia through which the sheet metal enters, and the third being
situated below the other two in order to guide the sheet in the direction towards
the delivery side of the bath; or in place of the third roller a fixed guide may be
used.
According to another modification we also enclose the delivery or exit side of the
bath with a hood in a similar manner to the receiving side, whereby the further
advantage is gained that the galvanised plates in issuing from the bath into the
heated atmosphere of the hood are not subject to deterioration by sudden cooling
as is at present the case. In this case the sheet metal may either issue between
revolving skimmers as first above described, or if the vapours or gases confined in
the hood are not such as would act injuriously upon the zinc, the layer of muriate
of ammonia might either be greatly diminished or even entirely dispensed with,
and in the latter case the arrangement of revolving skimmers might also be
dispensed with, the sheet iron being made to issue through a narrow opening in
the hood, arranged in a similar manner to that described with reference to the
receiving side.
If both the receiving and delivery side of the bath are enclosed, a partition is
provided in the hood, dipping into the zinc so as to separate the two parts. By
enclosing one or both sides of the bath, as above described, the farther advantage
is gained, that the fumes and gases within the enclosed space, having a pressure
equal to or exceeding that of the atmosphere, prevent ingress of air, and the surface
of the molten metal is thus protected to a considerable extent from oxidation.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frederick Braby and Arthur Charles Moore in the Great Seal Patent
Office on the 28th December 1877.
FREDERICK BRABY, of No. 358, Euston Road, in the County of Middlesex,
.Galvanised Iron Manufacturer, and ARTHUR CHARLES MOORE, of Ida Wharf,
Deptford, in the County of Kent, Galvanised Iron Manufacturer. IMPROVEMENTS
IN THE MEANS AND APPARATUS FOR GALVANISING IRON, OR COATING IT WITH ZINC
AND TIN."
In galvanising sheet iron, netting, or other extended surfaces, these are immersed
into a bath of molten zinc at one side thereof, and pass out of the bath at the other
side. The zinc bath requires to have a layer of muriate of ammonia or other
deoxidiser upon its surface, in order to prevent the molten zinc from oxidising on
the surface through contact with the air, and also to cleanse the surface of the iron
before it passes into the zinc. The muriate of ammonia has itself, however, an
injurious effect upon the coated or galvanised iron as it emerges from the bath,
discoloring the coating of zinc thereon.
One part of our present Invention has for its object to avoid this injurious effect,
and it consists in providing at the delivery or exit side of the bath a narrow space,
which is kept clear of the flux, through which space the sheet is made to pass as it
issues from the bath. This space may be formed between two partitions that dip
down into the molten metal; but as the portion of the surface of the metal lying
between these partitions would, if it remained quiescent, be subject to oxidation, we
keep the fluid metal in motion between the partitions so as always to change the
surface thereof, and we effect this by making these partitions in the form of rollers,
which are partially immersed in the metal, and are kept revolving in opposite
directions, that is to say, the sides facing each other are always ascending, whilst
the opposite sides descend. These rollers, besides separating the flux on either side
from the space between them, act also as " continuous skimmers," continually changing
and keeping clean the surface through which the galvanised sheet issues, and such
portions of the zinc as may adhere to them and become oxidised on the exposed
portions of their periphery, become again deoxidised by being carried through the
flux on their outer descending sides.
The revolving skimmers are placed sufficiently far apart to permit the sheets to
issue from between them without touching them, the sheets being guided in the
proper direction by rollers or guides below the surface of the molten metal or by
hooked rods worked by hand.
Instead of two revolving skimmers as above described a single skimmer may be
employed at the one side of the delivery space, a fixed plate or partition, which
may be the end of the bath, forming the other side; but, as in that case, portions of
zinc might become deposited on the fixed partition, and remain stationary there, so
as to become oxidised, we prefer to employ the two skimmers, both sides of the
space being thus kept clean by their revolution.
In order to economise muriate of ammonia it may be confined to a small space,
immediately at the back of each revolving skimmer, by means of metal plates
arranged parallel with the revolving skimmers at a certain distance therefrom, and
dipping into the molten zinc, or nearly so, and if desired such plates may have
hoods attached thereto covering in the layers of flux, so as to enclose the fumes
arising therefrom, spouts closed by covers being provided in such hoods, through
which fresh flux may be introduced when required, and openings or tubes for
leading away the fumes evaporated therefrom to condensers or elsewhere. The
other part of the surface of the zinc bath beyond the delivery side may be covered
with a layer of spent muriate of ammonia with aluminum, or with any other
suitable material that will float on and cover the molten zinc, protecting it from
contact with the atmosphere without being itself acted upon by the molten
metal.

page_text: For some classes of work the flux on the delivery side of the bath may be
dispensed with, the sheet being caused to issue through a narrow space between
partitions or revolving skimmers dipping into the molten metal, as above described.
Another part of our Invention has for its object to obviate the inconvenience and
loss that now arises from the evaporation of the volatile constituents from the layer
of muriate of ammonia covering the molten zinc of the bath on the receiving or
entrance side thereof, such vapours, as also the gaseous products of combustion from
the incandescent fuel at the side of the bath, being at present allowed to escape free
into the workshop, occassioning a loss of material, and also considerable inconvenience
to the operatives.
According to one modification of our Invention we enclose the receiving side of
the zinc bath by a hood or cover, having a lip that dips down into the molten
metal of the bath at or about the middle thereof, thus completely separating the
receiving from the delivery side thereof, and extends from that point, either to the
side of the bath, if it is desired only to confine the vapours thereof, or to the brick-
work inclosure.beyond the fuel at the side of the bath, if it be desired also to confine
the gases arising from the fuel; or separate covers or enclosures may be made
to convey the products of combustion into the hood over the receiving side of
the bath.
At a short distance above the top of the bath we provide in the hood a long
narrow opening or slit, through which the sheet to be galvanised is inserted, such
opening having, by preference, on the one edge a strip of elastic or yielding packing
material, such as vulcanised caoutchouc, while the other edge is formed by a hinged
plate pressed against the packing by a weight or spring, so that when no sheet is
being passed through, the opening is closed against the escape of vapour or gases.
The inner surface of the hood is made of any suitable material that will not be
quickly destroyed by the muriate of ammonia fumes and other gases, and the foriner
may either be allowed to condense inside the hood and fall back on to the bath, or
the fumes and gases may be conducted from the hood through a pipe to a condenser
or elsewhere.
The gases arising from the burning fuel being mainly carbonic
anhydride, carbonic oxide, and nitrogen, will not seriously injure the muriate of
ammonia, or the iron or zinc, and the heat thereof will tend to dry the metal sheets
(which are wet from the pickling bath), and also warm them before they pass into
the zinc bath, the steam thus generated mixing with the other gases, and being
conducted away with them.
The closed end surfaces of the hood may be provided with doors, through which,
when required, the spent muriate of ammonia may be removed, and fresh material
inay be introduced by those doors, or by covered spouts provided at the front of the
hood.
The hood may have one or more openings covered by loaded flaps to act as safety
valves for allowing the escape of gases, should the pressure thereof rise unduly, and
similar valves or flaps may be provided in the escape pipe before mentioned,
such valves being, by preference, rather more lightly loaded than those on the
hood.
For the purpose of guiding the sheet iron in the proper direction as it enters the
bath three rollers may be provided, two being either above the layer of the flux, or,
by preference, partially immersed in the bath with a space between them covered
with muriate of ammonia, through which the sheet metal enters, and the third
being situated below the other two, in order to guide the sheet in the direction
towards the delivery side of the bath; or in place of the third roller. a fixed guide
may be used.
According to another modification we also enclose the delivery or exit side of the
bath with a hood in a similar manner to the receiving side, whereby the further
advantage is gained that the galvanised plates in issuing from the bath into the
heated atmosphere of the hood are not subject to deterioration by sudden cooling,
as is at present the case. In this case the sheet metal may either issue between
revolving skimmers, as first above described, or, if the vapours or gases confined in

page_text: the hood are not such as would act injuriously upon the zinc, the layer of muriate
of ammonia might either be greatly diminished or even entirely dispensed with,
and in the latter case the arrangement of revolving skimmers might also be
dispensed with, the sheet iron being made to issue through a narrow opening in the
hood arranged in a similar manner to that described with reference to the receiving
side.
If both the receiving and delivery side of the bath are enclosed, a partition is
provided in the hood dipping into the zinc, so as to separate the two parts. By
enclosing one or both sides of the bath, as above described, the farther advantage is
gained that the fumes and gases within the enclosed space having a pressure equal
to or exceeding that of the atmosphere, prevent ingress of air, and the surface of the
molten metal is thus protected to a considerable extent from oxidation.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 shews a transverse section, and Fig. 2 shews a longitudinal section of one
arrangement of our before-described improved apparatus for galvanising iron.
A is the bath or tank containing molten zinc, and heated by the fires B, B, on
either side. On the receiving side the bath is enclosed by a hood C, which may or
may not dip down into the molten zinc, and which is, by preference, made with an
inclined outer side C, as shewn, in which is formed a flap door C, opening inwards,
for the introduction of the sheets of metal to be galvanised, which door will by its
own weight tend to keep closed against the hood when sheets of metal are not being
introduced, so as to prevent the escape of fumes emanating from the bath.
At
If necessary, the edge of the opening may be provided with packing material,
and the flap may be acted on by springs, so as to insure a perfect enclosure.
the top the hood may be provided with a flue or tube D for leading the fumes away,
either to a condenser or to the open air, as may be desired. Or, if the hood be
sufficiently large, the flue may be dispensed with and the fumnes merely allowed to
condense within the hood, the condensed particles partly falling back on to the layer
of muriate covering the molten zinc, and partly depositing upon the sides of the
hood, whence they may be removed from time to time by scrapers introduced
through the door C2, which is made with a second hinge at C3, so that only the lower
part is opened for introducing the sheet metal.
In addition to the advantages herein-before mentioned of preventing loss of the
flux by evaporation, and inconvenience to the workmen from the fumes and hot
gases given off, the use of the hood to the zinc bath affords the further advantage
that by means of the confined heat the sheet metal, which is wet from the pickling
bath, becomes quickly dried as it is introduced into the hood and before it is
immersed in the molten zinc, thereby preventing the explosions that now sometimes
occur through the moisture on the sheets coming in contact with the molten zinc,
resulting in the scattering of the zinc and injury to the workmen.
On the opposite or delivery side of the bath are provided the before-described
revolving skimmers E, E, consisting of cylindrical metal rollers, immersed with their
axles somewhat below the surface of the zinc, and carried by side frames F, F.
These skimmers are arranged so that a certain space intervenes between them, as
shewn, such space being sufficiently large to allow of the thickest sheets of metal to
be galvanised passing between them without touching them. They have rotary
motion in contrary directions imparted to them by means of the gearing G, G, so
that they both revolve from the inner towards the outer sides, as indicated by the
arrows. The surface of the molten metal situated between the skimmers is kept
free of flux, which is confined to the outer sides thereof, and by their above-
mentioned motion they continually remove or "skim" any oxidised particles or
other impurities from the surface of the zinc between them, such particles being
carried round by them, and becoming again deoxidised and removed from their
surface as they pass through the flux and molten metal on the other side.
We prefer to mix with the muriate of ammonia a proportion of sand for forming
the flux, as we find that it assists in cleaning the skimmers.

page_text: The sheet metal to be galvanised is guided as it passes from the receiving side
through the bath to between the skimmers, firstly, by means of the shoot H, or salt
box, into which the flux is introduced, and which leads from the hood A down to a
guide I, that directs the sheet metal between two rollers K, K, to which rotary
motion is imparted by gearing L, so as to deliver the sheet metal into other curved
guides ML which lead the sheet up between the revolving skiminers. The guides and
rollers are supported by side frames N suspended in the bath, as shewn. On issuing
from between the skimmers the metal sheet is seized by tongs O, by which it is
drawn up vertically as it issues, and is thus prevented from coming in contact with
the surface of the skimmers.
As before stated, in order to economise flux, this may be confined to a narrow
space on the outer side of each skimmer by means of metal plates dipping into the
bath, and these spaces may be hooded over to confine the fumes; also, the entire
delivery side of the bath may be enclosed by a hood in a similar manner to the
receiving side, but by preference separated therefrom by a partition, as indicated by
the dotted lines at P, Fig. 1, the hood being in this case provided with a door for
the issue of the sheets. The hood, both on the receiving and on the delivery side
may, if desired, be extended to the dotted lines at Q, so as to enclose also the fires
on either side of the bath and thus confine the gases arising therefrom, and the
portions of the hood over the fires may be made as separate chambers or flues, so as
to keep the gases from these separate from the fumes rising from the zinc bath:
Having thus described the nature of our Invention and in what manner the same
is to be performed, we wish it to be understood that we are aware that galvanised
sheet metal has been delivered from the zinc bath by means of rollers dipping more
or less into the bath and gripping the sheet as it passes out, and we in no way claim
such an arrangement, but we claim,-
First. Providing at the delivery side of the zinc bath a narrow space on the surface
of inolten zinc, which is kept clear of flux and impurities, the sheet metal being
made to issue through such space in such manner that neither at the point of issue,
nor immediately above or below it, its surface shall come in contact with anything
but the molten zinc, substantially as and for the purpose herein described.
Second. The use, for forming and keeping clear the narrow space on the surface
of the molten zinc referred to in the preceding claim, of revolving skimmers, arranged
and operating substantially as herein described.
Third. The use, for enclosing the receiving side of the zinc bath, or both the zinc
bath and the fire, of a hood provided with an opening for the introduction of the
sheet metal, such opening being provided with a door or other means whereby it is
kept closed when sheets are not being introduced, substantially as herein described.
Fourth. The use, for enclosing the delivery side of the zinc bath, or both the bath
and the fire, of a hood provided with an opening for the exit of the sheet metal, such
opening being provided with a door or other means whereby it may be kept closed
when sheets are not issuing therefrom.
In witness whereof, I, the said Frederick Braby, have hereunto set my hand
and seal, this Twenty-fourth day of December, in the year of our Lord One
thousand eight hundred and seventy-seven.
FREDERICK BRABY: (L.S.)