Improvements in the Recovery of Tin from Old Tins and Clippings and Waste Pieces of Tinned Iron.
Year: 1894

page_text: Date of Application (in United Kingdom), 16th Apr., 1894
Complete Specification Left, 16th Jan., 1895-Accepted, 16th Feb., 1895
Improvements in the Recovery of Tin from Old Tins and Clippings
and Waste Pieces of Tinned Iron.
I, HENRI ALEXANDRE MARTIN of 2 Avenue de Friedland, Paris, Chemist, do
hereby declare the nature of this invention to be as follows:-
According to my invention I employ for the purpose of untinning or recovering
the tin from old tins and clippings and waste pieces of tinned iron, sulphuric acid
together with any suitable oxydant, such for instance as nitric acid, or nitrates, or
chlorates, or oxygen or air, in such manner that the oxydant may furnish about an
equivalent of free oxygen per equivalent of sulphuric acid..
If I employ, for instance, chlorate of potash which can furnish six equivalents of
oxygen, then I use one equivalent of the chlorate for six equivalents of sulphuric
acid. The untinning bath is completed by adding about four pounds of water per
pound of sulphuric acid, generally the sulphuric acid of commerce at 53° Beaumé.
The waste pieces of tinned iron are then dropped in by successive charges and
left until the tin coating has disappeared and as long as the bath will dissolve tin.
The temperature should not exceed about 50° C. at the start; it may be raised
to a certain extent as the bath becomes weakened.
The tin thus dissolved in the bath is then separated in the form of metal or salt
by a suitable chemical or metallurgical process.
I prefer to use the sulphuric acid of commerce at 53° Beaumé. The employment
of such a sulphuric acid bath offers the considerable advantage of permitting the
treatment of tin ingots, clippings and waste pieces of tinned iron, old tins, lead
coated iron and other pieces containing lead in various proportions either in their
substance or their outer covering or coating, or in the solder used for uniting
different pieces.
Further according to the nature of the objects treated the bath compound with
sulphuric acid base may have sulphuric acid alone or sulphuric acid with hydro-
chloric acid added thereto, and the proportions of the two acids may be up to about
equal equivalents of each, the proportions of the other ingredients remaining
unchanged.
Dated this 16th dex of Anril 1894
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.

page_text: Improvements in the Recovery of Tin from Old Tins and Clippings
and Waste Pieces of Tinned Iron.
I, HENRI ALEXANDRE MARTIN of 2 Avenue de Friedland, Paris, Chemist do
hereby declare the nature of this invention and in what manuer the same is to
be performed to be particularly described and ascertained in and by the following
statement :-
According to my invention I employ for the purpose of untinning or recovering
the tin from old tins and clippings and waste pieces of tinned iron, sulphuric acid
together with any suitable oxydant such for instance as nitric acid or nitrates or
chlorates or oxygen or air, in such manner that the oxydant may furnish about an
equivalent of free oxygen per equivalent of sulphuric acid.
If I employ for instance chlorate of potash which can furnish six equivalents of
oxygen, then I use one equivalent of the chlorate for six equivalents of sulphuric
acid. The untinning bath is completed by adding about four pounds of water per
pound of sulphuric acid, generally the sulphuric acid of commerce at 53° Beaumé.
The waste pieces of tinned iron are then dropped in by successive charges and
left until the tin coating has disappeared and as long as the bath will dissolve tin.
The temperature should not exceed about 50° C. at the start; it may be raised
to a certain extent as the bath becomes weakened. The tin thus dissolved in the
bath is then separated in the form of metal or salt by a suitable chemical or metal-
lurgical process.
I prefer to use the sulphuric acid of commerce at 53° Beaumé. The employ-
ment of such a sulphuric acid bath offers the considerable advantage of permitting
the treatment of tin ingots, clippings and waste pieces of tinned iron, old tins, lead
coated iron and other pieces containing lead in various proportions either in their
substance or their outer covering or coating, or in the solder used for uniting
different pieces.
Further according to the nature of the objects treated the bath compound with
sulphuric acid base may have sulphuric acid alone or sulphuric acid with hydrochloric
acid added thereto and the proportions of the two acids may be up to about equal
equivalents of each the proportions of the other ingredients remaining unchanged.
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.
The application and use for untinning clippings or waste pieces of tinned iron
old tins &c. of a bath composed of 1) water 2) sulphuric acid at 53° Beaumé,
alone or mixed with a proportion of hydrochloric acid of commerce up to equal
equivalents of the two acids, and 3) any oxydant such as nitric acid a nitrate or
chlorate, or oxygen, or air, substantially in the proportions and as and for the
purpose hereinbefore set forth.
Dated this 16th day of January 1895
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.