Improvements in Galvanizing Apparatus.
Year: 1899

page_text: Date of Application, 14th Nov., 1899-Accepted, 6th Jan., 1900
Improvements in Galvanizing Apparatus.
I, GEORGE HARRISON, Chartered Patent Agent, of the Firm of D Young & Co.,
of 11 and 12, Southampton Buildings, London, E.C., 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 apparatus for galvanizing metals, and is especially
applicable for galvanizing iron or steel in the form of sheets, plates, wires,
netting or strips.
In galvanizing iron, a dross is formed as soon as the iron is brought in contact
with the galvanizing molten zinc, and with apparatus as now commonly con-
structed, the dross referred to settles to the bottom of the vessel or tank con-
taining the zine bath, and the said bath soon becomes contaminated by the dross
which adheres to the iron plate, etc., as the latter is passed into and out of the
galvanizing bath. The formation of the dross referred to is rapid and soon
accumulates in the tank or vessel in such quantities or amounts as to requiro
suspension of the process for the purpose of removing the dross, thereby occasion-
ing delay, expense, and waste of galvanizing metal.
This invention has for its object to galvanize iron or steel in the form of
sheets, strips, etc. in a manner as will be described whereby the formation of
the dross is reduced to a minimum, and that which is formed is automatically
removed from contact with the iron plate, etc., and from the galvanizing bath
into and out of which the iron plate is passed, and whereby a maximum number
of plates, etc., may be galvanized with a given quantity or amount of galvanizing
metal as will be described.
In accordance with this invention, there is employed an apparatus comprising
an outer vessel, and a smaller inner vessel located in said outer vessel below
the upper edge thereof and above the bottom of the outer vessel to form a
continuous chamber extended beneath the inner vessel from one side to the other
of the outer vessel. The inner vessel is filled with galvanizing metal and the
chamber beneath the said vessel is filled with metal of greater specific gravity
upon which rests galvanizing molten metal in the outer vessel above the inner
vessel, so that in galvanizing the iron plate, de., it may pass through a sub-
stantially thin layer of galvanizing metal at one side of the apparatus and into
the bath of metal of greater specific gravity, out of which it passes into and
through the substantially thin layer of galvanizing metal at the other side of
the apparatus, the dross formed by contact of the iron plate with the galvanizing
metal resting on the surface of the bath of metal of greater specific gravity
and being automatically removed therefrom substantially as fast as formed by
overflowing into the chamber containing the body of galvanizing metal.
These and other features of this invention will be pointed out in the claim
at the end of this specification.

page_text: Fig. 1 is a longitudinal section of one form of galvanizing apparatus embody-
ing this invention, and
Fig. 2, a transverse section of the apparatus shown in Fig. 1 on the line 2-2.
The apparatus shown in Fig. 1 as embodying this invention, consists of an
outer vessel or tank a and a smaller vessel or tank al located within the vessel
or tank and separated therefrom to form chambers aa³, which of themselves
are of less area than the tank or vessel a and both of which communicate directly
with the space a' within the tank a above the upper edge of the vessel a', which
space is of substantially the area of the tank a. The vessel is shown in
Fig. 1 as separate from the vessel a, but it practically forms a partition wall
within the vessel a below its upper edge so as to divide the vessel a into
practically two chambers as a which communicate with the common chamber
or space a. The vessel a' may be suspended within the vessel a, by means of
straps or arms b, and its end walls 2, 3, may be substantially in contact with
the end walls 4, 5 of the vessel a.
The chamber or space a may and preferably will be filled with a metal of
greater specific gravity than the galvanizing metal and preferably lead.
The galvanizing metal indicated by the broken lines may and preferably
will normally fill the chamber a and substantially fills the space or chamber a*,
so as to form in this space a substantially thin or shallow layer of galvanizing
metal. As shown in Fig. 2, the inner chamber a continues under the bottom
wall of the chamber and when filled with molten lead substantially up to
the level with the upper edge of the said wall, forms two connected substantially
upright columns of lead, which, for convenience, may be marked 10-12.
With the apparatus shown in Fig. 1, the process of galvanizing may be
carried on as follows:-
The iron or steel plates, strips, etc., are entered into the chamber at one
side of the apparatus and are passed under the bottom wall of the chamber a
and up out of the vessel a at the opposite side of the apparatus.
To facilitate the passage of the plates, strips, etc. through the chamber or
space a³, one or more rollers may be suspended from the bottom of the inner
vessel By reference to Fig. 2, it will be seen that a substantially shallow
body of the zine or galvanizing metal lies above the column of lead 10, and
consequently the amount of dross formed by combination of the zine with the
iron surfaces of the plates, etc. is in this manner reduced, as the formation of
the dross increases in proportion to the depth of the zinc through which the
iron plate is passed and also to the time the said plate remains in contact with
the zinc.
The dross formed on the plate by the action of zine is removed therefrom by
the entrance of snid plate into the bath of metal of greater specific gravity,
namely, the column 10 of the lead bath, and the dross being lighter than the
lead floats to the top of the lead bath and forms a layer, which is indicated
in Fig. 2 by the heavy black lines 13. As the layer 13 of dross accumulates,
it overflows the edge of the partition wall of the chamber a³, and being heavier
than the zinc gravitates to the bottom of the chamber al, where it accumulates
as represented by .
The lead bath is made of sufficient quantity of lead to keep its upper surface
rubstantially on a level with the upper edge of the wall of the chamber a, to
thereby avoid the formation of a layer of dross between the lead and zine of
any material or excessive depth, so as to reduce to a minimum the quantity of
dross through which the iron plate, etc. is passed. The plate, etc. on its passage
through the lead bath is cleansed, so that it presents a clean surface to the action
of the layer of zine above the column 12 of lead in the chamber a at the opposite
side of the apparatus, and as the iron plate emerges from the column 12 of
molten lead, it passes up through the zinc layer above it and is nicely galvanized.
Owing to the superior condition of the iron plate as it emerges from the
lead bath, a smaller amount of dross is formed on its passage out through the

page_text: layer of zinc, but whatever dross is thus formed, accumulates over the column 12
of lead and forms a thin layer 15, and as this layer 15 is built upon, the dross
overflows into the chamber a. As the dross accumulates in the chamber a³,
it gradually displaces the zine in said chamber and acts to automatically renew
the layer of zine in the chamber a'. The dross may be allowed to accumulate
in the chamber until the latter is substantially filled, if desired, and it may
then or previous thereto, be removed by suitable means, as for instance, by
ladle or dipper, without in the least interfering with the process of galvanizing.
The zinc bath may be renewed without interruption of the process, by placing
oheets or pieces of zinc in the chamber a where it is melted, and in this manner
the layer of zino in the chamber or space af may be renewed and kept sub-
stantially constant for an indefinite time, thereby enabling the galvanizing
process to be carried on continuously with but little attention or care and at
a minimum expense. So also, it will be noticed, that a maximum extent or
amount of surface may be galvanized with a given quantity of zinc owing to
the minimum formation of dross, which is automatically removed substantially
as fast as formed, from the surface of the lead bath.
It will be understood, that the vessel a in practice is heated in any suitable
manner to keep the lead in a molten state, and the heat of the lead bath melts
the zinc.
It is preferred to place the lead bath in the chamber a, and the zinc in the
chamber a, as shown, but if desired the lead bath may be placed in the
chamber and the zine in the chamber a, in which ense the plates, etc., will
be passed through the layer of zine above the lead bath in the chamber a, and
the dross will overflow into the chamber and automatically feed the zine in
the chamber a² up to the layer above the chamber a³.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, as communicated
to me by my foreign correspondent I declare that what I claim is:
--
1. A galvanizing apparatus comprising un outer vessel, and a smaller inner
vessel located in said outer vessel below the upper edge thereof and above the
bottom of the outer vessel to form a continuous chamber extended beneath the
inner vessel from one side to the other of the outer vessel, substantially as
described.
2. A galvanizing apparatus comprising an outer vessel, and a smaller inner
vessel suspended in aid outer vessel below the upper edge thereof and separated
from the outer vessel to leave a chamber a², substantially as described.
Dated this 14th day of November 1899
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.