An Improved Process for Removing Tin from Tinned Scrap.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
An Improved Process for Removing Tin from Tinned Scrap.
We, HERBERT ROBERT STODDARD COLEMAN, of 118, Sycamore Road, Smethwick,
in the County of Stafford, Analytical Chemist, and GEORGE CRUICKSHANK, of
121 to 131 Camden Street, in the City of Birmingham, Chemical Manufacturer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the process of stripping the tin
from tinned scrap or waste, and consists as follows;-
We first make a hot saturated solution or electrolyte of caustic soda, or caustic
potash, or we may use a mixture of both or any of their salts, this solution is
then placed in an iron vat, and in connection with this vat we arrange a suitable
basket or cage in which we place the tinned scrap which is undergoing treatment,
such basket or cage being made so as to be readily raised or lowered into or out
of the solution, and having suitable means by which it may be revolved or agitated
whilst in the said vat, and it also has suitable connections whereby it forms the
anode of the vat. Preferably the cathodes of the vat are of sheet iron of as large
an area as possible, and suitably hung in the vat.
In order to heat the electrolyte, we arrange a steam pipe in the interior and
near the bottom of the vat, such pipe being insulated by a rubber pipe or con-
nection or other suitable insulating medium.
In connection with this vat we use a powerful electric current, such being
conveyed by suitable connections from the dynamo or other source of electrical
energy.
The scrap tinned iron (as received from the tin plate workers) is placed in the
basket and lowered into the solution and the current passed therethrough, which
precipitates some of the tin from the said scrap. We then place the scrap in a vat
containing preferably hot water, but it may be cold water which further collects
the loosened tin. It is then passed on to a vat containing a solution of sulphuric
hydrochloric or nitric acid, such solution being preferably hot, and we may pass
a current therethrough or not as may be desired, this again throwing down a
precipitate of tin. After this it is treated in a bath of boiling water, which
removes the remainder of the tin therefrom, and further dries the remaining
scrap iron and thus retards its rusting.
The precipitated tin and the solutions containing such we may treat in any
suitable manner to convert same into salts of market value.
If desired, the first bath of water may be dispensed with, and the scrap passed
from the caustic bath to the acid bath.
noted this 26th day of July 1800
CHARLES T. POWELL,
Applicants' Agent.

page_text: An improved Process for Removing Tin from Tinned Scrap.
We, HERBERT ROBERT STODDARD COLEMAN, of 118, Sycamore Road, Smethwick,
in the County of Stafford, Analytical Chemist, and GEORGE CRUICKSHIANK, of
121, to 131, Camden Street, in the City of Birmingham, Chemical Manufacturer,
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 improvements in the process of stripping the tin from
tinned scrap or waste, and consists as follows;-
We first make a hot saturated solution or electrolyte of caustic soda, or caustic
potash, or we may use a mixture of both or any of their salts, the proportion of
such solution being about 7 pounds of salts to 10 pounds of water; this solution
is then placed in an iron vat. The articles or scrap to be stripped is now placed
in an ordinary basket or cage or the like, which is suitably arranged to be lifted
into or out of the vat, and also preferably revolved, all by any of the well known
contrivances. Suitable usual means are adopted by which the said contents of
the cage or basket are electrically connected to the positive current so as to form
then as the anodes.
Preferably the cathodes of the vat are of sheet iron of as large an area as
possible, and suitably hung in the vat in any convenient manner.
In order to heat the electrolyte, we use an ordinary steam pipe arrangement
in the interior and near the bottom of the vat, such pipe being insulated by a
rubber pipe or connection or other suitable insulating medium.
A powerful electric current is used of about 75 to 100 amperes per square foot
of anode surface, such being conveyed by suitable connections from the dynamo
or other source of electrical energy, to the various connections. The scrap tinned
iron (as received from the tin plate workers) is placed in the basket and lowered
into the solution, and remains immersed from 20 to 40 minutes according to the
nature of the tin on the scrap, and the current is passed therethrough, by which
a portion of the tin is precipitated from the said scrap. We then place the scrap
into another vat containing boiling water, which further washes off and collects
the loosened tin. It is then passed on to a vat containing a solution of sulphuric,
hydrochloric or nitric acid in the proportion of about 1½ pounds acid to 10 pounds
water, such solution being preferably hot, and we may pass a current there-
through or not as may be desired, this again throwing down a precipitate of tin,
and practically loosening the whole of it. After this it is washed in a bath of
boiling water, which removes the remainder of the tin therefrom, and further
dries the remaining scrap iron and thus retards its rusting.
The precipitated tin and the solutions used containing such, we may treat in
any suitable manner to convert same into salts of market value.
If desired, the first bath of water may be dispensed with, and the scrap passed
from the caustic bath to the acid bath, as although usually the said bath is
advantageous, still it is not absolutely necessary.
Having now particularly described and ascertained the nature of this our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
-
1. In a process for reclaiming tin from tinned scrap, the treatment of the tinned
scrap in a hot solution of caustic soda, caustic potash, or the like alkaline salts,
and electrically connected with suitable cathodes and thence into a boiling water
bath, substantially as set forth.

page_text: 2. The process of reclaiming tin from tinned scrap which consists in treating
the scrap in a hot solution of caustic soda, caustic potash or the like alkaline
salts, with electric current and suitable cathodes, an optional boiling water
bath, and passing the said scrap thence into a vat containing a solution of
sulphuric, hydrochloric, or nitric acid, with or without heat, and with or without
electric current, and a further boiling water washing bath substantially as set
forth and described.
Doted this 20th don of
1000
CHARLES T. POWELL,
Applicants' Agent.
International Exchange Buildings, 158, Edmund Street, Birmingham.