Improvements in or relating to the Treatment or Utilization of Scrap Tin or Terne Plates and the like.
Year: 1890

page_text: Date of Application, 5th Feb., 1890
Complete Specification Left, 16th Oct., 1890-Accepted, 17th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Treatment or Utilization of
Scrap Tin or Terne Plates and the like.
A communication from abroad by EUGÈNE CAREZ, of Brussels, in the Kingdom of
Belgium.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster, and 323, High Holborn, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention to be as follows:-
Tin plates are formed of sheets of iron rolled thin and covered with tin which
contains more or less lead.
Tin is a metal the actual value of which is very great compared with iron.
There is no practical and economical means known to my correspondent at present
existing of industrially removing the tin from the iron, so that on the one hand the
iron may be obtained completely free from tin and capable of being again used as
such for any of its ordinary industrial uses, and on the other hand the tin may be
obtained free from iron.
The herein described process not only allows of the tin being removed from
the iron, but also of cleaning the iron of lead and the re-use of this iron.
Hitherto, by the usual processes of stripping, iron was only obtained in such a state
that its industrial utilization as metal was impossible, consequently it had but a
very low value, the imperfect cleaning not allowing of it being used for casting.
For this purpose, there is employed either the sulphurets of sodium residues from the
soda manufacture (Leblanc process) or the polysulphides of calcium mixed with
hyposulphite of calcium which is transformed by means of carbonate of soda into
sulphuret and hyposulphite of soda, or of sulphurets of sodium mixed with a little
nitrate of sodium, resulting from the manufacture of nitrate of barium by means of
sulphide of barium and nitrate of sodium, or any other sulphuret of sodium more or
less pure, and the sulphides more or less sulphuretted are transformed into polysulphide
by boiling them with a slight excess of sulphur.
The presence of strange salts does not hinder the reaction. The polysulphide of
sodium, thus obtained, is concentrated to about 30 degrees Beaumé iu a vat heated
by steam and maintained at a temperature of 50 degrees to 70 degrees Centigrade
(sulphides of potassium can be employed instead, but sulphides of sodium are preferable,
their price being much lower).
The tin plate scrap is placed in a series of iron wire baskets, which are attached
for instance to an endless chain, and they alternately ascend and descend by means
of a winch or of any other suitable arrangement in a vat containing the solution of
polysulphide of sodium heated as aforesaid, and to which has been previously added
chloride of ammonium. The addition of this salt is necessitated by the solubility
of sulphuret of iron in the polysulphide of sodium solution, it counteracts this
dissolution and even any attacking of the metallic iron by the alkaline sulphide.
The basket remains for three or four minutes in the polysulphuretted ammonia
solution, then rises out of it and descends into a vat containing water where the
cleaned iron is washed; it then ascends from this second vat in order to be emptied.
The polysulphide does not attack the metallic iron, only the oxidised portions are
removed and precipitated in the form of insoluble sulphide, the lead which always
accompanies tin is also transformed into insoluble sulphide, the tin alone remains in
solution. It absorbs a portion of the sulphur of the polysulphide being transformed
into sulphide of tin; the latter acts like sulpho-acid, combines with the sulphide of
sodium and yields an alkaline sulphostannate very soluble in water.

page_text: Knowing the proportion of the sulphuretted solution and the approximate pro-
portion of tin covering the iron of a tin-plate, one knows what quantity of tin plates
the sulphuretted solution is capable of stripping. When the point of saturation is
attained, the solution is decanted in order to separate therefrom the insoluble sulphides
of iron and lead which should have collected and been deposited at the bottom of the
vat; and the sulphostannate solution is obtained.
It suffices to add a little hydrochloric acid to the same in order to obtain the
sulphide of tin in a pure condition which can be used for the preparation of pure
metallic tin or of the various salts employed in industries.
Dated this 4th day of February 1890
WM. P. THOMPSON & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or relating to the Treatment or Utilization of
Scrap Tin or Terne Plates and the like
A communication from abroad by EUGENE CAREZ, of Brussels, in the Kingdom of
Belgium, Engineer.
1, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both
in the County of Lancaster, and 323, High Holborn, in the County of Middlesex,
Civil Engineer, 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 :-
Tin plates are formed of sheets of iron rolled thin and covered with tin which
contains more or less lead.
Tin is a metal the actual value of which is very great compared with iron.
There is no practical and economical means known to my correspondent at present
existing of industrially removing the tin from the iron so that on the one hand
the iron may be obtained completely free from tin and capable of being again
used as such for any of its ordinary industrial uses, and on the other hand the
tin may be obtained free from iron.
The hereindescribed process not only allows of the tin being removed from the iron,
but also of cleaning the iron of lead and the re-use of this iron.
Hitherto, by the usual processes of stripping, iron was only obtained in such
a state that its industrial utilization as metal was impossible, consequently it had
but a very low value, the imperfect cleaning not allowing of it being used for
casting.
For this purpose, there is employed either the sulphurets of sodium residues
from the soda manufacture (Leblanc process) or the polysulphides of calcium mixed
with hyposulphite of calcium which are transformed by means of carbonate of soda
into sulphuret and hyposulphite of soda, or of sulphurets of sodium mixed with
a little nitrate of sodium, resulting from the manufacture of nitrate of barium by
means of sulphide of barium and nitrate of sodium, or any other sulphuret of
sodium more or less pure, and the sulphides more or less sulphuretted are transformed
into polysulphide by boiling them with a slight excess of sulphur.
The presence of strange salts does not hinder the reaction. The polysulphide
of sodium thus obtained is concentrated to about 3 degrees Beaumé in a vat
heated by steam and maintained at a temperature of 50 degrees to 70 degrees
Centigrade (sulphides of potassium can be employed instead, but sulphides of sodium
are preferable, their price being much lower).
The tin plate scrap is placed in a series of iron wire baskets, which are
attached for instance to an endless chain, and they alternately ascend and descend
by means of a winch or of any other suitable arrangement in a vat containing
the solution of polysulphide of sodium heated as aforesaid, and to which has been

page_text: previously added chloride of ammonium. The quantity of ammonium chloride
employed is approximately of the quantity of anhydrous polysulphide of sodium
used. The addition of this salt is necessitated by the solubility of sulphuret of
iron in the polysulphide of sodium solution, it counteracts this dissolution and
even any attacking of the metallic iron by the alkaline sulphide.
The basket remains for three or four minutes in the polysulphuretted ammonia
solution, then rises out of it and descends into a vat containing water where the
cleaned iron is washed; it then ascends from this second vat in order to be emptied.
The polysulphide does not attack the metallic iron, only the oxidised portions are
removed and precipitated in the form of insoluble sulphide, the lead which always
accompanies tin is also transformed into insoluble sulphide, the tin alone remains
in solution. It absorbs a portion of the sulphur of the polysulphide being transformed
into sulphide of tin, the latter acts like sulpho-acid, combines with the sulphide of
sodium and yields an alkaline sulphostannate very soluble in water.
Knowing the proportion of the sulphuretted solution and the approximate proportion
of tin covering the iron of a tin-plate, one knows what quantity of tin plates the
sulphuretted solution is capable of stripping. When the point of saturation is
attained, the solution is decanted in order to separate therefrom the insoluble
sulphides of iron and lead which should have collected and been deposited at the
bottom of the vat; and the sulphostannate solution is obtained.
It suffices to add a little hydrochloric acid to the same in order to obtain the
sulphide of tin in a pure condition which can be used for the preparation of pure
metallic tin or of the various salts employed in industries.
Having now particularly described and ascertained the nature of the said inven-
tion, 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 :-
The process of treating or utilising scrap tinned iron by means of solution of
alkaline polysulphide and chloride of ammonium and separating the tin as a sulpho-
stannate or sulphide, substantially as described.
Dated this 14th day of October 1890.
WM. P. THOMPSON & Co.,
Agents for the Applicant.