AN IMPROVED PROCESS FOR RECOVERING THE TIN CONTAINED IN OR UPON WASTE METALS, ALLOYS AND OTHER WASTE PRODUCTS
Year: 1882

page_text: LETTERS PATENT to Charles Denton Abel of No. 28 Southampton Buildings
Chancery Lane in the County of Middlesex, for an Invention of
" AN
IMPROVED PROCESS FOR RECOVERING THE TIN CONTAINED IN OR UPON
WASTE METALS, ALLOYS AND OTHER WASTE PRODUCTS" A communication
from abroad by Dr. Hermann Alfred Schulte of Düsseldorf in the German
Thin
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at
the Office of the Commissioners of Patents on the 17th February 1882.
CHARLES DENTON ABEL of No. 28 Southampton Buildings Chancery Lane in
the County of Middlesex "AN IMPROVED PROCESS FOR RECOVERING THE TIN
CONTAINED IN OR UPON WASTE METALS, ALLOYS, AND OTHER WASTE PRODUCTS"
[A communication from broad by Dr. Hermann Alfred Schulte of Düsseldorf in
the German Empire]
This Invention relates to an improved process for recovering the tin contained
in or upon waste metals, alloys and other waste products such as tin plate waste,
old utensils, cauldrons tin ash, and the like. In applying it to large pieces of
alloys however it is necessary first to reduce these to granules or a finely divided
state, in order that the liquid employed for dissolving the tin may act with
sufficient rapidity and energy. The said liquid possesses the property of only
dissolving the tin and it is obtained as follows:-A lye is prepared of any desired
degree of concentration from hydrate of soda or potash and water; preferably a
lye containing from 15 to 20 per cent of hydrate of soda or potash is employed as
giving very good results, but under circumstances a weaker or a stronger lyc may
be used.
The lye is heated in a suitable vessel while oxide of lead-Massicot is at the same
time added until the liquid is completely saturated, and a small excess of the oxide
of lead is then given, which is indicated by the lye assuming a yellowish red
colour. By means of the lye thus prepared the tin can be dissolved without
attacking any other metal with which it may be mixed, or that may be coated
therewith.

page_text: The chemical process involved is as follows:-The tin combines with the
solution and its place is taken by the lead contained therein in the form of oxide,
this becoming deposited in metallic form consequently the more tin goes into the
solution the poorer in lead will it become. The scrap metal or alloy to be treated
is left so long in the solution until the whole of the tin is dissolved. The
precipitated metallic lead is principally deposited in a spongy condition upon
the metal which has been deprived of its tin, but it can easily be removed there-
from mechanically, for instance by scraping or washing. The lye having become
saturated with tin so that its action ceases, there will be no more oxide of lead
in solution therein, and the tin solution can now be treated in the known
manner.
It is to be observed that if the saturated liquid is to be further treated it should
be removed from the fire to cool in order that any remaining particles of lead
or lead oxide may be precipitated. For further operations of course only the
clear liquid is taken which is separated in any suitable manner from the
precipitate
It must however be previously ascertained in the usual manner whether there
are still traces of oxide of lead in the solution, as in the further treatment these
might otherwise be detrimental to the end product to be obtained. The sufficient
saturation of the liquid with tin is ascertained in the easiest way by placing
therein a piece of tin or tin plate for from 5 to 10 minutes and then examining
whether such piece has been attacked.
If a sufficient excess of oxide of lead has been added to the liquid in the first
instance, the liquid obtained as end product will be composed according to the
formula:-
1. If the lye was made with hydrate of soda:—
Sn O, Na. O + aq.
2. If made with hydrate of potash :
Sn O KO+aq.
In employing this process on a large scale a lye prepared with hydrate of soda
will generally be used, as it will then be possible to obtain stannate of soda from
the liquid at the end of the process, as will be seen from the formula. A mixture
of the hydrates of soda and of potash may also be employed.
The metals to be treated may with advantage be placed in perforated drums
that are made to revolve slowly in the lye, in order that by the friction of the
pieces against each other and against the sides of the drum the lead deposit may
become removed and thus clean surfaces be presented for the liquid to act upon so
as to considerably increase the energy of the action.
The lye product obtained by this process consisting of a mixture of oxide of
lead and lead sponge can after proper washing be converted into oxide in the usual
manner or be otherwise disposed of.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Denton Abel in the Great Seal Patent Office on the
14th August 1882.
"
CHARLES DENTON ABEL. of No. 28 Southampton Buildings Chancery Lane in
the County of Middlesex "AN IMPROVED PROCESS FOR RECOVERING THE TIN
CONTAINED IN OR UPON WASTE METALS, ALLOYS AND OTHER WASTE PRODUCTS
A communication from abroad by Dr. Hermann Alfred Schulte of Düsseldorf in
the German Empire.
This Invention relates to an improved process for recovering the tin contained
in or upon waste metals, alloys and other waste products, such as tin plate waste,
old utensils, cauldrons, tin ash and the like. In applying it to large pieces of
alloys however it is necessary first to reduce these to granules or a finely divided
state, in order that the liquid employed for dissolving the tin may act with
sufficient rapidity and energy. The said liquid possesses the property of only
dissolving the tin, and it is obtained as follows: A lye is prepared of any desired
degree of concentration from hydrate of soda or potash and water preferably a lye
containing from 15 to 20 per cent. of hydrate of soda or potash is employed, as
giving very good results, but under circumstances a weaker or a stronger lye
may be used. This lye is heated to boiling point in a suitable vessel with addition
of a considerable excess of any oxide of lead, such as Pb O, Pb, О₁, Pb O, &etc.
By means of the lye thus prepared the tin can be dissolved without attacking
any other metal with which it may be mixed, or that may be coated therewith.
The chemical process involved is as follows: The dissolved or suspended oxide of
lead belonging to any degree of oxidation, yields its oxygen to the metallic tin and
this passes into solution as stannic acid under formation of stannate of of soda or
potash, while the lead is precipitated in metallic form. From this it follows that
the richer in oxygen the oxide of lead employed is, the less is required, and the
quicker will be the solution of the tin.
The scrap metal or alloy to be treated is left so long in the solution until the
whole of the tin is dissolved. The precipitated metallic lead is principally
deposited in a spongy condition upon the metal which has been deprived of its tin,
but it can easily be removed therefrom mechanically, for instance by scraping or
washing. The lye having become saturated with tin so that its action ceases, there
will be no more oxide of lead in solution therein, and the tin solution can now be
treated in the known manner. It is to be observed that if the saturated liquid is
to be further treated it should be removed from the fire to cool in order that any
remaining particles of lead or lead oxide may be precipitated. For further
operations of course only the clear liquid is taken, which is separated in any
suitable manner from the precipitate. It must however be previously ascertained
in the usual manner whether there are still traces of oxide of lead in the solution,
as in the further treatment these might otherwise be detrimental to the end
product to be obtained. The sufficient saturation of the liquid with tin is
ascertained in the easiest way by placing therein a piece of tin or tin plate for
from 5 to 10 minutes, and then examining whether such piece has been attacked.
If a sufficient excess of oxide of lead has been added to the liquid in the first
instance, the liquid obtained as end product will be composed according to the
formula:
1 If the lue mas made with hoodunda of

page_text: will generally be used, as it will then be possible to obtain stannate of soda from
the liquid at the end of the process, as will be seen from the formula. A mixture
of the hydrates of soda and of potash may also be employed.
The metals to be treated may with advantage be placed in perforated drums that
are made to revolve slowly in the hot lye, in order that by the friction of the
pieces against each other and against the sides of the drum the lead deposit may
become removed and thus clean surfaces be presented for the liquid to act upon so
as to considerably increase the energy of the action. The by product obtained by
this process consisting of a mixture of oxide of lead and lead sponge can after
proper washing be converted into oxide in the usual manner or be otherwise
disposed of.
Having thus described 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 claim :
First. The process for recovering the tin from waste metals or alloys consisting
in the preparation of a lye of any desired concentration composed of hydrate of
soda or hydrate of potash and water which is heated to to boiling point and mixed
with lead oxide of any composition, in which lye the metals to be treated are
allowed to remain until it is perfectly saturated with tin, that is to say until all
the caustic soda or potash contained in the liquid is converteu into stannate of soda
or potash.
Second. The use in the above process of a mixture of the hydrates of soda and
potash
In witness whereof I the said Charles Denton Abel have hereunto set my
band and seal this Twentieth day of July in the year of our Lord One