Year: 1886

page_text: Date of Application, 20th May, 1885.
Complete Left, 21st Feb., 1887.
Complete Accepted, 7th Apr., 1887.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and Engineers,
of 35, Southampton Buildings, Chancery Lane, in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
This invention has for its object more especially an improved method of treating
cuttings or waste of tin plate in order to remove the metallic tin, but it is also
applicable to the separation of tin combined with metals such as copper, zinc, or lead,
or in combination with oxygen. The process which forms the subject of my invention
consists first in making solutions of tin, but preferably of protochloride of tin slightly
acid and afterwards of extracting the tin in a metallic state by means of the simple
apparatus used in the ordinary process of electrotyping. This apparatus in its simplest
form as ordinarily used for the electrical deposit of copper consists of a porous vessel
filled with a saline solution or acidulated water into which a bar or plate of zinc is
immersed the porous vessel being placed in a larger vessel filled with a sufficiently
concentrated solution of sulphate of copper.
A mould of the object to be coated with copper is rendered a conductor of electricity
in the usual way and is connected to the zinc by a copper wire by which it is suspended
in the outer vessel, the copper in which is deposited upon it in continually increasing
thickness and the solution of sulphate of copper is kept to its proper strength by the
addition of fresh crystals.
In order to adapt this simple process to the separation of tin quickly and economically;
I reduce the latter to a solution in suitable solvents the metallic tin being deposited
from the salts thus obtained upon sheets of tin plate placed round the porous vessel
and communicating with the zinc by a conducting wire of sufficient size.
Supposing cuttings of fresh tin plate are to be used as often happens I place them
in vessels of material unaffected by the chemical agents employed and I keep them in

page_text: movement by any convenient mechanical means so as to prevent them from adhering
together and so escaping the action of the acid liquids.
These acid liquids may vary according to the character of the tin cuttings or
fragments but I prefer to use a mixture of hydrochloric and nitric acids in about the
following proportions, (which however may be varied more or less according to
circumstances), viz:-
250 to 300 Kilogrammes of Hydrochloric acid, and about
8 to 12 Nitric acid,
used in strong vessels lined with material not affected by the chemical agents, such as
stoneware, porcelain, glass, slate, stone, or a composition of two parts of silicious sand
and one part of sulphur, the acids being mixed with about a thousand litres of water
and heated to a temperature of about 80 to 100 degrees.
The vessels described are heated by the introduction of steam from an ordinary
boiler either introduced direct or passed through coils so as to heat the liquid which is
to dissolve the tin.
While the process of solution is going on a certain proportion of iron is also
dissolved in removing the last particles of tin, the fragments being removed when the
further solution would cease to be economical.
250 to 300 Kilogrammes of commercial hydrochloric acid with 8 to 12 Kilogrammes
of Nitric acid added to 100 to 1200 litres of water are sufficient to effect the separation
of the tin from a ton of fragments of tin plate such for example as preserved fruit cans.
Instead of Nitric acid, perchloride of iron may be used by which the tin is quickly
and effectually separated.
The perchloride of iron is preferably produced by dissolving 80 to 90 Kilogrammes
of peroxide of iron in 300 to 350 Kilogrammes of hydrochloric acid. This quantity
is sufficient to separate the tin from a fon of tin plate, the quantity of water being the
same as before, so that the metal may be completely covered.
In order that the solutions of tin may be sufficiently concentrated, for use by the
simple electrical process first described part of the water which. they contain is
evaporated, or preferably the liquid remaining after a first process of separation is used
in subsequent ones, adding to the solvent liquid the acids and the perchloride of iron
in the proportions already given.
Dated this 30th day of Mo 100

page_text: Tinned Plates or from Alloys or Salts of Tin.
A communication to me from abroad by MANUEL RAMOS-GARCIA, of Paris, in the
Republic of France, Manufacturer.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of Middlesex
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 (that is to say) :-
This invention has for its object more especially an improved method of treating
cuttings or waste of tin plate in order to remove the metallic tin, but it is also
applicable to the separation of tin combined with metals such as copper, zinc, or lead,
or in combination with oxygen. The process which forms the subject of my invention
consists first in making solutions of tin, but preferably of protochloride of tin slightly
acid and afterwards of extracting the tin in a metallic state by means of the simple
apparatus used in the ordinary process of electrotyping. This apparatus in its
simplest form as ordinarily used for the electrical deposition of copper consists of a
porous vessel filled with a saline solution or acidulated water into which a bar or plate
of zinc is immersed the porous vessel being placed in a larger vessel filled with a
sufficiently concentrated solution of sulphate of copper.
A mould of the object to be coated with copper is rendered a conductor of electricity
in the usual way and is connected to the zinc by a copper wire by which it is suspended
in the outer vessel, the copper in which is deposited upon it in continually increasing
thickness and the solution of sulphate of copper is kept to its proper strength by the
addition of fresh crystals.
By this means the deposit of copper continually increases.
In order to adapt this simple process to the separation of tin quickly and economically,
I reduce the latter to a solution in suitable solvents the metallic tin being deposited
from the salts thus obtained upon sheets of tin plate placed round the porous vessel
and connected with the zine by an electrical conducting wire of sufficient size.
Supposing cuttings of fresh tin plate are to be used as often happens I place them
in vessels of material unaffected by the chemical agents employed and I keep them in
movement by any convenient mechanical means so as to prevent them from adhering
together, since if left at rest they would remain adherent and to a great extent escape
the action of the acid liquids.
These acid liquids may vary according to the character of the tin cuttings or
fragments but I prefer to use a mixture of hydrochloric and nitric acids in about the

page_text: following proportions, (which however may be varied more or less according to
circumstances), viz:-
250 to 300 Kilogrammes of hydrochloric acid, and about
8 to 12 (or even less) Nitric acid,
used in strong vessels lined with material not affected by the chemical agents, such as
stoneware, porcelain, glass, slate, stone, or a composition of two parts of silicious sand
and one part of sulphur, the acids being mixed with about a thousand litres of water
and heated to a temperature of about 80 to 100 degrees.
The vessels described are heated by the introduction of steam from an ordinary
boiler either introduced direct or passed through coils so as to heat the liquid which is
to dissolve the tin.
While the process of solution is going on a certain proportion of iron is also
dissolved in removing the last particles of tin, the fragments being removed when the
further solution would cease to be economical.
250 to 300 Kilogrammes of commercial hydrochloric acid with 8 to 12 Kilogrammes
of nitric acid added to 1000 to 1200 litres of water are sufficient to effect the separation
of the tin from a ton of fragments of tin plate such for example as preserved food cans.
Instead of Nitric acid, perchloride of iron may be used by which the tin is quickly
and effectually separated.
The perchloride of iron is preferably produced by dissolving 80 to 90 Kilogrammes
of peroxide of iron in 300 to 350 Kilogrammes of hydrochloric acid. This quantity
is sufficient to separate the tin from a ton of tin plate, the quantity of water being the
same as before, so as to completely cover the metal from which the tin is to be removed.
The use of perchloride is new for the purpose and in the manner described and
forms an important part of the invention, a special feature of which is the use of
chemical means for separating the tin from the iron which allows the materials to be
kept in movement which would be impossible if it were attempted to separate the tin
by electrical means after the proper solutions of tin had been prepared for that purpose.
Moreover, in order to provide sufficiently concentrated solutions of tin for the
simple electrical apparatus described a part of the water which they contain may be
evaporated the remaining liquid being used after a first process for the purpose of
subsequent ones the acids and perchloride of iron being added in the proportions
already given.
Having now particularly described and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I declare that what I claim is :-
1. The use of the simple apparatus and method described for reducing to the
metallic state solutions of tin prepared by chemical means from tinned plate or other
materials containing them substantially as described.
2. The use for the separation of the tin of perchloride of, iron substantially in the
manner described.
3. The use of the apparatus described combined with a suitable system of separating
tin from tinned plate or from solutions containing tin by which they can be obtained
from metals containing tin in the form of alloy or otherwise and also for the treatment
of oxides of tin either natural or produced artificially substantially as described.
4. The production by the methods described of iron from which the tin has been
entirely removed.
5. The utilization of the salts of iron produced by the improved processes described.
This 10th day of Tabuary 1007
EDWARDS & Co.,
Agents for the Patentée.