Tinned Flate.
Year: 1886

page_text: OI Tinned Flate.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co. Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of my invention to be as follows :-
This invention relates to an improved process of recovering tin from scraps of
tinned plate by means of hydro-chloric acid.
In all the processes of recovering tin from scraps of tinned plate by hydrochloric
acid in a liquid or gaseous state a product is obtained which contains besides
protochloride of tin, protochloride of iron, but the latter in such varying quantities
that the product cannot be directly used.
All the processes heretofore known for separating the tin from these solutions
consist chiefly in precipitating the metallic tin by means of zinc.
In these processes the valuable precipitating medium zinc is lost, as no advan-
tageous method of treating the final lyes, which consist of chloride of zinc and
protochloride of iron, is known.
By means of the present process, the solution of protochloride of tin and proto-
chloride of iron, obtained in the recovery of the tin from scraps of tinned plate by
hydrochloric acid, can be treated in a comparatively inexpensive manner, and the
greater portions of the hydrochloric acid used and of the dissolved iron are
re-obtained.
According to the said process the combined solutions of protochloride of tin and
protochloride of iron are mixed, while being agitated in closed vessels at the
ordinary temperature, with finely divided carbonate of lime, until a sample of the
filtered liquid no longer contains tin.
The reaction takes place according to the following formula,
8 Sn Cl₂ + 3 H, O + Ca CO₂ = Sn O Sn Cl, 3 H, O + CO2 + Ca CL
Protochloride of iron is not precipitated from the carbonate of lime, as the
precipitation takes place in closed vessels and in carbonic acid gas.

page_text: The oxy-protochloride of tin is not soluble in the cold liquid in presence of a
very slight excess of carbonate of lime, and it can be separated from the lye of
protochloride of iron and chloride of calcium by pressure.
These expressed lyes contain, besides, protochloride of iron, as much chloride
of calcium as corresponds with half the equivalent of the tin which was contained
therein.
These lyes are subsequently evaporated and the product is decomposed by
sulphuric acid in an oven, and all the hydrochloric acid contained therein is
recovered, and the decomposing product, consisting of gypsum and proto-sulphate
of iron, is treated so as to obtain green vitriol.
The pressed protochloride of tin is suspended in water in a second closed vessel,
and while being boiled, is treated with fresh quantities of finely divided carbonate
of lime, until all oxyprotochloride is converted into protoxide.
The reaction takes place according to the following formula,
Sn O Sn Cl, 3 H₂O + Ca CO, = 2 Sn O + 3 H₂O + CO₂ + Ca Cl
Any protochloride of iron which may still be mixed with the oxyprotochloride
cannot be precipitated; pure protoxide of tin is obtained if the operation is
properly conducted.
The protoxide of tin is separated from the lye containing chloride of calcium,
and a little protochloride of iron by pressing it, and then carefully washing the
same until chlorine can no longer be traced in the washing water. It can then
either be reduced to metal or treated directly to obtain tin salts.
In works of great extent, considerable quantities of pure carbonic acid are
obtained which can, with advantage, be utilized for industrial purposes.
In lieu of the carbonate of lime any carbonic acid combinations of the alkaline
earths can be used.

page_text: of Tinned Plate.
I, HENRY HARRIS LAKE; of the firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, 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 :—
This invention relates to an improved process of recovering tin from scraps of
tinned plate by means of hydrochloric acid.
In all the processes of recovering tin from scraps of tinned p'ate by hydrochloric
acid in a liquid or gaseous state a product is obtained which contains besides
protochloride of tin, protochloride of iron, but the latter in such varying quantities
that the product cannot be directly used.
All the processes heretofore known for separating the tin from these solutions
consist chiefly in precipitating the metallic tin by means of zinc.
In these processes the valuable precipitating medium zinc is lost, as no advan-
tageous method of treating the final lyes, which consist of chloride of zinc and
protochloride of iron, is known.
By means of the present process, the solution of protochloride of tin and proto-
chloride of iron, obtained in the recovery of the tin from scraps of tinned plate by
hydrochloric acid, can be treated in a comparatively inexpensive manner, and the
greater portions of the hydrochloric acid; used, and of the dissolved iron are
reobtained.
According to the said process the combined solutions of protochloride of tin and
protochloride of iron are mixed, while being agitated in closed vessels at the
ordinary temperature, with finely divided carbonate of lime, until a sample of the
filtered liquid no longer contains tin.
The reaction takes place according to the following formula,
2 Sn Cl, +3 H, O + Ca CO₂ = Sn O Sn Cl, 3 H₂ O + CO₂ + Ca Cl₂.
Protochloride of iron is not precipitated from the carbonate of lime, as the
precipitation takes place in closed vessels and in carbonic acid gas.
The oxy-protochloride of tin is not soluble in the cold liquid in presence of a
very slight excess of carbonate of lime, and it can be separated from the lye of
protochloride of iron and chloride of calcium by pressure.
These expressed lyes contain, besides protochloride of iron, as much chloride of
calcium as corresponds with half the equivalent of the tin which was contained
therein.
These lyes are subsequently evaporated and the product is decomposed by
sulphuric acid in an oven, and all the hydrochloric acid contained therein is
recovered, and the decomposing product, consisting of gypsum and proto-sulphate
of iron, is treated so as to obtain green vitriol.

page_text: The pressed protochloride of tin is suspended in water in a second closed vessel,
and while being boiled is treated with fresh quantities of finely divided carbonate
of lime, until all oxyproto-chloride is converted into protoxide.
The reaction takes place according to the following formula,
Sn O Sn Cl, 3 H, O + Ca CO, = 2 Sn O + 3 H, O + CO, + Ca Cl
Any protochloride of iron which may still be mixed with the oxyprotochloride
cannot be precipitated, pure protoxide of tin is obtained if the operation is
properly conducted.
The protoxide of tin is separated from the lye containing chloride of calcium,
and a little protochloride of iron by pressing it, and then carefully washing the
same until chlorine can no longer be traced. in the washing water. It can then
either be reduced to metal or treated directly to obtain tin salts.
In works of great extent considerable quantities of pure carbonic acid are
obtained which can, with advantage, be utilized for industrial purposes.
In lieu of the carbonate of lime any carbonic acid combinations of the alkaline
earths can be used.
Having now particularly described and ascertained the nature of the said
invention, 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 obtaining tin from lyes, containing protochloride of tin and
protochloride of iron, which are obtained in the recovery of the tin from scraps
of tin-plate, consisting in treating these lyes with finely divided carbonate of lime.
or other carbonate of the alkaline earths, whereby the tin precipitates in the form
of oxyprotochloride of tin or as protoxide of tin.
Dated thin 17th day of Navambar 1986