Improved Method of and Apparatus for Pickling Metal Articles.
Year: 1893

page_text: Date of Application; 15th Aug., 1893
Complete Specification Left, 15th June, 1894-Accepted, 28th July,
1894
PROVISIONAL SPECIFICATION.
Improved Method of and Apparatus for Pickling Metal Articles.
I, SHERARD OSBORN COWPER-COLES 16, Adam Street, Manchester Square
in the County of Middlesex Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention relates to a method of and apparatus for pickling metal articles.
The chief features of my said invention consist in the removal of the scale or oxide,
and in employing weak acid pickling solutions, in combination with currents of
electricity which are frequently reversed in direction, and in constantly circulating
the pickling solution and removing therefrom the scale which is detached from the
metals under treatment, the said solution being at the same time restored, if required,
to its original strength. Other features of my said invention are hereinafter set
forth and comprise simple and easily-manipulated apparatus whereby my said
invention may be carried into effect.
It is characteristic of my invention that the pickling solution does not require to
be very strong, 5 per cent.; or even less of free acid being sufficient, and that the
acid does not so soon become ineffective as is the case with the acids used in the
ordinary methods of pickling heretofore in use. It is well known that ordinary
pickling-solutions must be strong and must be frequently renewed, which is
objectionable and costly, and moreover, the operation of pickling takes a con-
siderable time if it is to be well done.
According to my invention I provide a solution of a suitable acid, containing,
for example 5%, or even less in some cases, of acid, and I treat the articles to be
pickled by immersing the same in the said solution which may be used either hot
or cold, and passing a current of electricity therethrough. The said articles are
connected to one or other of the conductors and therefore virtually form anodes
and cathodes in the bath, the current being frequently reversed during the
operation.
The heavier portions of scale detached from the articles under treatment, fall
to the bottom and are collected in trays or other suitable receptacles and removed at
intervals as required, but a quantity of the scale floats in the solution and would
be eventually dissolved therein. I prevent this by providing a. suitable pump or
other means for continually withdrawing the solution and passing the same
through a filtering medium and then back into the pickling tank. The scale
collected by the filter is removed therefrom by suitable mechanical means almost
as soon as it collects therein. The scale may also be removed by the employ-
ment of suitable centrifugal machinery to operate upon the solution containing
it. At the same time the strength of the solution may be restored by supplying
thereto the required quantity of fresh acid. By this means the solution is kept
from deteriorating and is maintained always in a condition for acting effectively.
The time required for cleaning any article by this method is much shorter
than is possible by the ordinary method. I preferably heat the pickling solution
by means of a steam coil or by passing into the solution steam which has
previously been freed from grease.
I sometimes provide that the articles especially if they are long thin plates shall
be fed continuously in at one end of the bath and out at the other, and I may pro-
vide revolving brushes or similar apparatus for brushing the said articles while
they are in the pickling bath or as they come out of the bath. Any acid retained by
the articles may be neutralized by an alkali supplied thereto by the brushes or
otherwise. Electrical contact with the moving plate can be made by any suitable

page_text: means, as for instance, by rollers or brushes bearing thereon. The plates are
treated in pairs, so that as aforesaid, one plate will. alternately form the anode and
the other the cathode.
In one construction of apparatus according to this invention, the vat is constructed
to receive a wooden tray or trough with suitable extensions thereon. The said
tray is so proportioned or so ballasted that if left to itself when the vat is charged
with the pickling solution the upper side of the tray will float just above the surface
of the said solution; therefore the extensions herein before referred to are provided
with flexible connections controlled by suitable gearing and led over guide sheaves,
for the purpose of sinking the frame or tray aforesaid, and of regulating its rise, as
may be necessary. In the said frame or trough at a suitable distance from the
bottom thereof, a removable grid or grating may be supported.
The scale from the said articles, passes through the grid or grating and
deposits itself upon the floor of the tray or trough so that by allowing the latter
to rise to the upper part of the vat the deposit can be conveniently removed;
in using a solution of sulphuric acid, the deposit partly consists of sulphate of
iron in the form of crystals. The object of the said grating is to prevent the
scale being stirred up by the movement of the articles being pickled.
The tray or trough is provided with grated or other drain openings, so that
when raised as aforesaid no liquid may remain in it. To facilitate the settlement
of the scale I provide in some cases magnets behind a diaphragm in the bath so
that the scale will be attracted towards the poles of the magnets and so collected
upon the diaphragm that it can easily be removed from time to time.
Within the said vat a coil of leaden or other steam pipes is provided, so that the
liquid in the vat can be maintained at the desired temperature.
In some cases it is advantageous to treat the articles before pickling and in
intervals of the process of pickling, with a sand blast.
All the apparatus according to this invention likely to be in the presence of
fumes arising from the acid solution or in contact with the solution, is preferably
given a protective coating of a metal or material which will prevent the injurious
action of the acid or the fumes upon parts so coated.
Dated this 14th day of August 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Method of and Apparatus for Pickling Metal Articles.
I, SHERARD OSBORN COWPER-COLES of 16 Adam Street, Manchester Square
in the County of Middlesex, Engineer do hereby declare the nature of this inven-
tion 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 a method of and apparatus for pickling metal articles
more especially intended for preparing them for receiving a coating of a metal or
of a metallic compound but applicable also for pickling them for any other purpose
and has for its object to provide an improved and economical method of and means
for effecting such pickling. The chief feature of the said invention consists in the
removal of the scale or oxide from the solution containing the articles being pickled
employing preferably weak acid pickling solutions.
The currents of electricity may be frequently reversed in direction, or not, as
desired. The scale or oxide can be removed from the pickling solution in the bath
itself or after it leaves the bath for instance by circulating it and separating the
scale or oxide by means of a filter and returning the solution to the vat the said
solution being first restored, if required, to its original strength. Other features of

page_text: the said invention are hereinafter set forth and comprise simple and easily
manipulated apparatus for carrying the said invention into effect.
The pickling solution does not require to be very strong, 5 per cent. or even less
(as low even as one per cent.) of free acid in the solution being sufficient and the
acid does not so soon become ineffective as is the case with the acids used in the
ordinary methods of pickling heretofore in use.
According to my invention I provide a solution of a suitable acid containing for
example 5 per cent. (or even less in some cases say even one per cent.) of acid and I
treat the articles to be pickled by immersing them in the solution (which is.
preferably used hot) and passing a current of electricity therethrough. The said.
articles are connected to the negative conductors and therefore virtually form
cathodes in the bath. The heavier portions of scale detached from the articles.
under treatment, fall to the bottom and are collected in trays or other suitable.
receptacles and are removed at intervals but a quantity of the scale floats in the
solution and would be eventually dissolved therein. I prevent this by providing a
suitable pump or other means for continually withdrawing the solution and passing it.
through a filtering medium and then back into the pickling tank. The scale
collected by the filter. should be removed therefrom by suitable mechanical means.
almost as soon as it collects therein. The scale may be removed from the solution.
by any other suitable means such for instance as by the employment of centrifugal
machinery to operate upon the solution containing it. At the same time the
strength of the solution may be restored by supplying thereto the required quantity
of fresh acid. By this means the solution is kept from deteriorating and ís.
maintained always in a condition for acting effectively.
The pickling solution may be heated by means of a steam coil or by passing into
the solution exhaust steam which has been freed from grease.
A suitable apparatus for carrying this invention into effect is illustrated in
Figures 1, 2 and 3 of the accompanying drawings. Figures 1 and 2 being sections..
at right angles to each other and Figure 3 being a plan of a pickling bath or vat
provided with arrangements according to this invention. The pickling vat A.
contains a tray trough or frame B which can be of wood and is capable of vertical.
movement between guides A' provided on the inside of the vat. The tray trough.
or frame B is capable of being raised and lowered in the vat it being preferably so.
proportioned or so constructed that if left to itself when the vat is charged with.
pickling solution the tray trough or frame will float on the solution so that the upper
side thereof (that is the bottom inside surface on which the scale rests) will be just.
above the surface of the said solution. To sink the tray B when necessary
extensions B' are provided at each corner and these extensions are connected to
flexible connections C which pass round guide sheaves C' and are connected to a
drum or winch D. In the tray B and at a suitable distance from the bottom. is a
removable grid or grating B which may be supported on beams B' and secured in
position by pins or wedges B. The tank is provided with three or more suspension
bars E E' (five are shewn in the drawing) to some of which E the carbon or other
anodes can be attached whilst the plates or other articles undergoing treatment are
attached to the other series E. The attachment of the anodes and of the plates or
other articles can be effected in any suitable way for instance by grips constituting
terminals and adapted to grasp the anode or article to be suspended. The bars are
attached by sockets e to castings which are connected to the conductors by
suitable terminals. The bath may be heated by an injection of cleansed exhaust.
steam or by means of a steam pipe G which may be arranged as shewn. When the
operation is in progress the scale from the articles being treated passes through the
grid or grating B and deposits upon the bottom of the tray B so that (after
removing the articles from the vat) by allowing the tray to rise slowly to the upper
part of the rat the deposited scale can be conveniently removed, the object of the
said grating B' being to prevent the scale from being stirred up by the movement.
of the articles undergoing treatment. The tray B itself may be provided with drain
openings so that when raised as aforesaid no liquid will remain in it. In some cases.

page_text: the articles to be treated can be suspended from all the bars instead of from only
alternate ones as hereinbefore described. I sometimes provide that the articles
(especially if they be long thin plates) shall be fed continuously in at one end of the
bath and out at the other and I may provide revolving brushes or similar apparatus
for brushing the said articles whilst they are in the pickling bath or as they come
out of the bath. Any acid retained by the articles may be neutralized by an
alkali supplied thereto by the brushes or otherwise. Electrical contact with the
moving plates can be made by any suitable means for instance by rollers or brushes
bearing thereon.
To facilitate the settlement of the scale I provide in some cases a magnet or
magnets behind a diaphragm or diaphragms in the bath so that the scale will
be attracted towards the poles of the magnet or magnets and so collect upon
the diaphragm or diaphragms and can easily be removed therefrom from time
to time.
This diaphragm or these diaphragms may be made of any suitable acid resisting
material such for example of sheet lead and it, or they, may constitute the lining or
part of the lining of the vat or may be arranged as a box inside the vat with the
magnet or magnets inside the box.
+
In some cases it is advantageous to treat the articles before pickling, and in
intervals of the process of pickling, with a sand blast.
All the parts of the apparatus according to this invention likely to be in the
presence of fumes arising from the said solution or in contact with the solution, are
preferably given a protective coating of a metal or material which will prevent the
injurious action of the acid or the fumes upon parts so coated. Cadmium is suitable
for such a protective coating.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In pickling or preparing metal articles for electro-deposition or other purpose
the removal of scale from the solution in which the electro deposition is effected
.substantially as hereinbefore described and illustrated by the examples instanced.
2. In pickling or preparing metal articles with a weak acid solution and the
employment of electric current reversed in direction at intervals, the combination
of means for removing the scale from the solution substantially as herein before
described.
3. The arrangement of pickling or preparing apparatus substantially as
hereinbefore described and illustrated in Figures 1. 2 & 3 of the accompanying
drawings.
4. The combination with a pickling tank or vat of a tray with a perforated top
and means for raising it or allowing it to rise for catching and removing the deposit
substantially as herein before described and illustrated by Figures 1, 2 and 3 of the
accompanying drawings.
5. In pickling or preparing metal articles the employment of a magnet or
magnets behind a diaphragm or diaphragms for facilitating the separation of the
scale from the pickling solution substantially as hereinbefore described.
Dated the 15th day of June 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, W.C., Agents.