IMPROVEMENTS IN PICKLING AND COATING STEEL AND IRON PLATES WITH TIN AND ALLOYS OF TIN, << AND APPLIANCES CONNECTED THEREWITH
Year: 1881

page_text: LETTERS PATENT. to Thomas Henry Cobley, Manufacturing Chemist,
Dunstable, Bedfordshire, and Claud Monckton, Civil Engineer, Manor House,
Harefield, Middlesex, for an Invention of IMPROVEMENTS IN PICKLING
AND COATING STEEL AND IRON PLATES WITH TIN AND ALLOYS OF TIN,
<<
AND APPLIANCES CONNECTED THEREWITH."
PROVISIONAL SPECIFICATION left by the said Thomas Henry Cobley and
Claud Monckton at the Office of the Commissioners of Patents on the
8th November 1881.
THOMAS HENRY COBLEY, Manufacturing Chemist, Dunstable, Bedfordshire, and
CLAUD MONCKTON, Civil Engineer, Manor House, Harefield, Middlesex. "IMPROVE-
MENTS IN PICKLING AND COATING STEEL AND IRON PLATES WITH TIN AND
ALLOYS OF TIN, AND APPLIANCES CONNECTED THEREWITH.".
Our Invention consists in a method more economical and expeditious than has
been hitherto employed for preparing or pickling steel and iron plates and coating
them with tin and its alloys, in the production of solutions for effecting the same,
and improved arrangements for such purposes.
We employ two kinds of solutions, the one acid and the other alkaline. We use
the acid solution for pickling and coating simultaneously, the alkaline solution for
coating only where the plates have been previously pickled in the ordinary way,
or for "finishing" plates pickled and coated (with a thin preliminary coating)
simultaneously in a bath of the acid solution.
These solutions we prepare from the ore of tin, or scrap, or waste of tin. Where
tin orc is employed it is first reduced by roasting with carbonaceous matter and
then treated with salts and acids as hereinafter described. The scrap requires no
preparation but simple immersion in the boiling solutions referred to.
For the acid baths we find convenient, where a sulphate bath is employed, to
take to every 140 gallons, more or less, of water 3 cwt., more or less, of crude
sulphate of soda, nitre cake, or salt cake, and after this has dissolved we add
[Price 41

page_text: 3 cwt., more or less, of sulphuric acid (chamber acid), bring this to boiling
temperature, and then add the prepared ore until nothing more is dissolved. When
scrap is employed it is immersed in the solution and kept boiling until the tin is
removed, then fresh scrap is added until the solution becomes inactive. Sulphuric
acid alone may be used, but we prefer the mixture with a sulphate for increasing
its activity. The scrap may then be washed and used as iron. Where a chloride
bath is found more convenient we make a saturated solution of common salt, and
to this we add hydrochloric acid equal in weight to the dry salt in the solution,
and we then proceed as before adding the prepared tin ore or scrap until no more
is dissolved. The solutions may be allowed to cool and crystallise and the crystals
of the double salts may be separated from the sour mother liquor, which may be
employed for a pickle bath, the double salts being used for coating or other
purposes.
The alkaline baths are made by subjecting the prepared tin ore or tin scrap to a
boiling solution of caustic alkali of 20° Twaddell, more or less (or what may be
obtained by boiling down the waste caustic lye of the papermaker, known as black
liquor), until it takes up sufficient tin to be available for use; or the black liquor
referred to may be mixed with tin ore, boiled down to dryness, and then burnt, and
The acid
the stannate of soda thus formed dissolved out by boiling with water.
bath, prepared as hereinbefore described, is further acidified by the addition of 1/th
by weight, more or less, of sulphuric acid to increase the pickling property.
The alloys, such-as-lead, zinc, or copper may be mixed with either bath in varying
proportions. In the alkaline baths the plumbate of zincate of soda or potash and
cupro ammonia are to be preferred; in the acid bath the sulphates of zinc and copper,
and the chloride of lead for the chloride bath only.
In coating steel or highly finished iron plates we proceed as follows:-The steel
plates are first pickled either in an ordinary pickle of sulphuric or hydrochloric
acid or a mixture of these, and after being well limed and washed are introduced
several times into the alkaline bath, and a current of electricity is passed through
the bath, preferably from a dynamo-electric machine, this being repeated until the
coating has reached the desired thickness.
The steel or highly finished iron plates may also be coated by passing them
through the acid bath first, to pickle and coat them simultaneously by subjecting
them to the action of an electric current, and after limeing and washing, finishing
them by passing them through the alkaline bath. We also prepare a special tin
plate for printing and decorating purposes by passing electro deposited tin plates
through what we call a white bath, which is simply produced by the addition of
acid tartrate of potassium to the sulphate or other convenient bath until a fine
white dead film forms on the surface. The plates are then well washed in hot
water and dried rapidly. Plates prepared in this manner may be printed upon as
easily as paper.
The iron plates are coated by passing them through the acid bath under the
influence of an electric current, and after neutralising and washing to remove the
last trace of acid, they are dipped into molten tin to give them a coating of metallic
tin which fills up the unevenness of surface existing in all ordinary iron plates and
gives them a bright surface without any further treatment.
:-
The finishing coating of metallic tin is applied as in ordinary tin plating
except that only one coating is given and no grease is employed, the main object
being in this way to produce a perfect greaseless plate. Our method is as
follows The plates are first fluxed in a flux pot containing a saturated solution
of any convenient or applicable flux capable of hindering oxidation of the tin, such
for instance as salammoniac, or a double salt of chloride of ammonium, and tin or
zinc. The plates are taken from this pot and dipped into the tin pot consisting of
molten tin, and are then passed through a cradle of rollers working in a pot
containing a saturated solution of a reducing or non oxidising agent, such as
chloride of ammonium, double salts of chloride of ammonium, and tin or chloride of
calcium, this solution being sweetened with sugar or glycerine. This latter pot is

page_text: called the wash or finishing pot. The plates after being rubbed aro fit for sale. Not
only greaseless plates but also plates to be tinned in the ordinary way may be
subjected to the preliminary or pickling process described. The alkaline baths aro
from time to time renewed or recuperated by pumping back the weakened solutions
into vats or receptacles containing prepared ore or scrap, and boiling until the
desired strength is reached.
The acid baths are treated as follows:-Fresh acid is added until the baths
become so saturated with iron that they are not available for further use. The tin
left in the bath solutions is precipitated out of them by means of sulphuretted
hydrogen or scrap zinc, and the sulphate of iron remaining is boiled down for
copperas. By continued use the stannate of soda or alkaline bath will become
partially decomposed and carbonate of soda formed; in this case we add at the
recuperation a small quantity of precipitated oxide of tin.
A most important feature of our Invention consists in the means employed for
saving time and labour in the process of depositing the metal upon the plates.
Their immersion in the bath and removal therefrom have hitherto been attended
with great difficulty, particularly in dealing with a large number of plates in a
given time. Celerity in manipulation is necessary to make a process such as we
employ commercially successful.
Hitherto plates undergoing electrical deposition have been connected into the
circuit by means of hooks, screws, or clamps, the use of which involves considerablo
expenditure of time and labour; this difficulty we overcome by introducing into
the bath a framework of wood or other nonconducting material provided with
grooves down which the plates are slid between the anodes and rest upon or
against a copper rod or bar connected with the negative pole, this bar being in any
accessible or convenient position. Thus the workman can immerse and remove
the plates quickly and without soiling his fingers as in an ordinary tinning
bath.
We also use for anodes iron plates, which are coated with tin by passing the
plates through the tinning pot. For brightening the surface of the plates whether
it be for finishing or for receiving a fresh coating we employ roller pressure, using
cold chilled rolls, this method being preferable to scratch brushing which involves
more labour and time, and by tearing off some of the metal renders the plates more
liable to corrosion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Henry Cobley and Claude Monckton in the Great Seal
Patent Office on the 6th May 1882.
THOMAS HENRY COBLEY, Manufacturing Chemist, Dunstable, Bedfordshire, and
CLAUD MONCKTON, Civil Engineer, Manor House, Harefield, Middlesex. "IMPROVE-
MENTS IN PICKLING AND COATING STEEL AND IRON PLATES WITH TIN AND
ALLOYS OF TIN, AND APPLIANCES CONNECTED THEREWITH."
Our Invention consists in a method more economical and expeditious than has
been hitherto employed for preparing or pickling steel and iron plates and coating
them with tin and its alloys, in the production of solutions for effecting the same,
and improved arrangements for such purposes.
Wo employ two kinds of solutions, the one acid and the other alkaline. Wo uso
the acid solution for pickling and coating simultaneously, the alkaline solution for
coating only where the plates have been previously pickled in the ordinary way,
or for "finishing" plates pickled and coated (with a thin preliminary_coating).
simultaneously-in-a-bath-of-the acid solution.
These solutions we prepare from the ore of tin, or scrap, or waste of tin, or from
granulated tin, tin dross, or from any material containing tin. When tin ore is
cumployed it is first reduced by roasting with carbonaceous matter, and then treated
with salts and acids, as hereinafter described. The scrap requires no preparation
but simple immersion in the boiling solutions referred to.
For the acid baths we find convenient, where a sulphate bath is employed, to
take to every 140 gallons, more or less, of water 3 cit., more or less, of crude
sulphate of soda, nitre cake, or salt cake, and after this has dissolved we add 3 cwt.,
more or less, of sulphuric acid (chamber acid), bring this to boiling temperature,
and then add the prepared ore until nothing more is dissolved.
When scrap is
employed it is immersed in the solution and kept boiling until the tin is removed,
then fresh scrap is added until the solution becomes inactive. Sulphuric acid alone
may be used, but we prefer the mixture with a sulphate for increasing its activity.
The scrap may then be washed and used as iron. Where a chloride bath is found
more convenient we make a saturated solution of common salt, and to this we add
hydrochloric acid equal in weight to the dry salt in the solution, and we then
proceed as before, adding the prepared tin ore or scrap until no more is dissolved.
The solutions may be allowed to cool and crystallise, and the crystals of the double
salts may be separated from the sour mother liquor, which latter may be employed
as a bath for pickling or for pickling and coating at one operation, the double salts
being used for coating or other purposes.
The alkaline baths are made by subjecting the prepared tin ore or tin scrap to
a boiling solution of caustic alkali of 20° Twaddell, more or less (or what may be
obtained by boiling down the waste caustic lye of the paper maker, known as black
liquor), until it takes up sufficient tin to be available for use; or the black liquor
referred to may be mixed with tin ore, boiled down to dryness, and then burnt,
and the stannate of soda thus formed dissolved out by boiling with water. From
50% to 10% of nitrate of soda may with advantage be added to the caustic solution
used in the preparation of the alkaline bath from tio ore or scrap. The acid bath,
prepared as hereinbefore described, is further acidified by the addition of ¼ by
weight, more or less, of sulphuric acid to increase the pickling property.
The alloys, such as lead, zinc, or copper, may be mixed with either bath in
varying proportions. In the alkaline baths the plumbate or zincate of soda or
potash and cupro ammonia are to be preferred; in the acid bath the sulphates of
zinc and copper, and the chloride of lead for the chloride bath only.

page_text: In coating steel or highly finished iron plates we proceed as follows:-The steel
plates are first pickled either in an ordinary pickle of sulphuric or hydrochloric
acid, or a mixture of these, and after being well limed and washed are introduced
several times into the alkaline bath, and a current of electricity is passed through
the bath, preferably from a dynamo-electric machine, this being repeated until the
coating has reached the desired thickness.
The steel or highly finished iron plates may also be coated by passing them
through the acid bath first, to pickle and coat them simultaneously by subjecting
them to the action of an electric current, and after limeing and washing, finishing
them by passing them through the alkaline bath. We also prepare a special tin
plate for printing and decorating purposes by passing electrodeposited tin plates
through what we call a white bath, which is simply produced by the addition of
acid tartrate of potassium to the sulphate or other convenient bath until a fine
white dead filin forms on the surface. The plates are then well washed in hot
water and dried rapidly. Plates prepared in this manner may be printed upon as
casily as paper.
The iron plates are coated by passing them through the acid bath under the
influence of an electric current, and after neutralising and washing to remove the
last trace of acid, they are dipped into molten tin to give them a coating of metallic
tin which fills up the uneveness of surface existing in all ordinary iron plates, and
gives them a bright surface without any further treatment.
The finishing coating of metallic tin is applied as in ordinary tinning, except
that only one coating is given and no grease is employed, the main object being in
this way to produce a perfect greaseless plate. Our method is as follows:-The
plates are first fluxed in a flux pot containing a saturated solution of any convenient
or applicable flux capable of hindering oxidation of the tin, such for instance as
salaiminoniac, or a double salt of chloride of ammonium and tin. The plates are
taken from this pot and dipped into the tin pot, consisting of molten tin, and are
then passed through a cradle of rollers working in a pot containing a saturated
solution of a reducing or non oxidising agent agent, such as chloride of ammonium or
double salts of chloride of ammonium and tin; this latter pot is called the wash or
finishing pot. The plates after being rubbed are fit for sale. Not only greaseless
plates, but also plates to be tinned in the ordinary way, may be subjected to tho
preliminary or pickling process described. The alkaline baths are from time to
time renewed or recuperated by pumping back the weakened solutions into vats or
receptacles containing prepared ore or scrap, and boiling until the desired strength
is reached.
The acid baths are treated as follows:-Fresh acid is added until the baths
become so saturated with iron that they are not available for further use. The
tin left in the bath solutions is precipitated out of them by means of sulphuretted
hydrogen or scrap zinc, and the sulphate of iron remaining is boiled down for
copperas; or the tin may be precipitated by the addition of carbonate of iron.
By continued use the stannate of soda or alkaline bath will become partially
decoin posed, and carbonate of soda formed; in this case we add at the recuperation
a small quantity of precipitated oxide of tin.
A most important feature of our Invention consists in the means employed for
saving time and labour in the process of depositing the metal upon the plates.
Their immersion in the bath and removal therefrom have hitherto been attended
with great difficulty, particularly in dealing with a lare number of plates in a
given time. Celerity in manipulation is necessary to make a process such as we
employ commercially successful.
Hitherto plates undergoing electrical deposition have been connected into the
circuit by means of hooks, screws, or clamps, the use of which involves considerable
expenditure of time and labour; this difficulty we overcome by introducing into the
bath a framework of wood or other non conducting material provided with grooves
down which the plates are slid between the anodes, and rest upon or against a
copper rod or bar connected with the negative pole, this bar being in any accessible

page_text: or convenient position. Thus the workman can immerse and remove the plates
quickly and without soiling his fingers, as in an ordinary tinning bath.
We also use for anodes iron plates, which are coated with tin by passing the
plates through the tinning pot; or they may be of an alloy of lead and tin cast to
the desired form. For brightening the surface of the plates, whether it be for
finishing or for receiving a fresh coating, we employ roller pressure, using cold
chilled rolls. A scouring machine may also be used, but it is better to avoid scratch
brushing, which involves more labour and time, and by tearing off some of the
metal renders the plates more liable to corrosion.
Having thus described the nature of our Invention, and in what manner the
same is to be performed, we claim,―
First. Simultaneously pickling and coating with tin and its alloys iron or steel
plates by subjecting them to the action of an acid bath, prepared and applied
substantially as herein described.
Second. Coating with tin or its alloys iron or steel plates previously pickled or
lightly coated in the manner referred to in the preceding claim by subjecting the
said plates to the action of an alkaline bath, prepared and applied substantially as
herein described.
Third. The herein described process for preparing special white plates for
printing.
Fourth. The herein described process for applying the finishing-coating-of-tin-
without the use-of-grease.
Fifth. In the baths for electrolytic coating, the use of a non-conducting frame
having grooves for receiving a number of plates arranged so that the plates rest
against or upon conductors, substantially as and for the purposes herein set forth.
In witness whereof, we, the said Thomas Henry Cobley and Claud Monckton,
have hereunto set our hands and scals this Fifth day of May, in the year of
our Lord One thousand eight hundred and eighty two.
MAC TIENRY CORLEY
rs