An Improved Process of Removing Tin from Tin Scrap or Tin Coated Metal.
Year: 1894

page_text: Date of Application, 2nd Jan., 1894-Accepted, 3rd Feb., 1894
Date of Application, 2nd Jan., 1894-Accepted, 3rd Feb., 1894
COMPLETE SPECIFICATION.
An Improved Process of Removing Tin from Tin Scrap or
Tin Coated Metal.
I, THOMAS GUY HUNTER of No. 1516 North Fifty Fifth Street, City of
Philadelphia, State of Pennsylvania, United States of America, Chemist, 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:
My invention has for its object the utilization of tin scrap by effecting the
separation of the coating of tin from the iron of which the sheet is made by a
process which may be carried on economically and will result in several different
products of a commercial value.
In the accompanying drawing I have illustrated one form of apparatus by
which my invention may be carried into effect, although it will be understood
that any other suitable apparatus may be employed, my invention residing in the
process described.
In this drawing F represents a suitable tank, preferably of wood, having an
open top and provided at its lower end with a valved discharge, f. At a short
distance above the bottom of the tank is a basket or grate, G, having vertical side
bars, g, terminating at a point above the top of the tank in eyes, g', to which
hoisting chains, h, may be attached to remove the grate from the tank, when
necessary. The grate, G, and bars, 9, are preferably constructed of gun metal or
other metal which will not be acted upon by the sulphate. Above the tank is
a valved pipe, I, through which water is supplied in the flushing operation
hereinafter described.
At a point below the tank, F, is a suitable tank, K, having an open upper end
and at various levels on one or more sides are tap holes, l, through which the
contents of the tank may be discharged, and this tank is adapted to receive the
contents of the tank, F, which, when discharged, flow through a conducting pipe
or trough, M, to the tank, K. At a suitable point above the tank, K, is a
valved water supply pipe, N, by which water is supplied for cleansing
purposes.
In carrying out my said process, I proceed to place within the tank, F, a supply
of so called ", scrap tin
consisting of sheet iron having on each side a thin coating
of tin, the scrap resting upon the grate and so leaving a space between the tin and
the bottom of the tank. I then pour into the tank sulphate, preferably sulphate
of copper, in solution, the sulphuric acid radical in which, having a greater affinity
for tin than for the copper will combine with the tin and form sulphate of tin,
precipitating metallic copper, which falls beneath the grate G, to the bottom of
the tank. After a time the tin coating is entirely combined with the sulphate
and held in solution forming sulphate of tin, leaving the scrap iron in a
pure state.
The sulphuric acid radical of the tin sulphate so formed having a greater affinity
for the iron immediately combines with the latter, forming sulphate of iron,
precipitating metallic tin.
The action of the sulphate on the iron is checked as soon as it takes up all the
iron it can hold in solution, forming sulphate of iron. When all the tin has
been precipitated the sulphate of iron with the precipitate of metallic tin and
copper is drawn off from the tank, F, through the trough or pipe, M, to the
tank K

page_text: By subsequently flooding the tank, F, with water all the remaining particles of
tin are washed to the bottom of the tank, F, whence it is drawn off, as before, to
the tank, K. The grate, G, which may, if desired, be provided with sides to form
a cage or basket, is then removed by the hoisting ropes or chains, h, and the pure
scrap iron removed.
The mixture in the tank K, consists of metallic copper, metallic tin, sulphate of
iron diluted to a greater or less extent by the flushing water, and small quantities
of minor impurities, such as lead, bismuth and phosphorus, which products and
by-products may be utilized in any way known to the arts, the sulphate of iron
being useful in dyeing and the copper and tin may be fused as an alloy, or separated
by any process, and the scrap iron melted for use in the arts.
In the drawing I have shown steam supply pipes, s, surrounding the cage or
basket in which the tin scrap is contained, so that, if necessary, heat may be used
to facilitate the operation, the said pipes being composed of any metal which the
sulphate will not attack.
I am aware that the use of au acidulated salt has heretofore been known for
forming sulphate of tin from tin scrap, sheet zinc being subsequently employed to
precipitate the tin; and do not claim such as my invention.
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 :
1. The herein described process of treating "tin scrap" consisting in subjecting
the tin scrap to the action of a sulphate and permitting such action to continue
until the tin has been precipitated in metallic form and sulphate of iron formed by
the action of the sulphate upon the iron of the tin scrap.
2. The hereindescribed process of treating "tin scrap" consisting in subjecting
the tin scrap to the action of a neutral solution of sulphate of copper and permitting
such action to continue until the copper and tin have been precipitated in metallic
form.
3. A process of treating "tin scrap," said process consisting in subjecting the
tin scrap to the action of a neutral solution of sulphate of copper, permitting such
action to continue until the copper and tin have been precipitated and sulphate of
iron formed, then removing the precipitate with the sulphate of iron, of Hushing
the remaining iron and finally removing said iron.
Dated this 2nd day of January 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.