A Process for the Recovery of the Tin and the Iron from Waste Pieces or Clippings of Tinned Sheet or other Iron or Steel.
Year: 1890

page_text: Date of Application, 25th Sept., 1890
Complete Specification Left, 25th June, 1891-Accepted, 25th July, 1891
PROVISIONAL SPECIFICATION.
A Process for the Recovery of the Tin and the Iron from Waste
Pieces or Clippings of Tinned Sheet or other Iron or Steel.
I CAMILLE LÉON CHARLES BERTOu of 11 Rue de St. Petersbourg. Paris
in the Republic of France do hereby declare the nature of this invention to be
as follows:-
My invention refers to improvements in the mode of recovering the tin and
the iron or steel from waste pieces or clippings of tinned' sheet iron or steel
according to which the tin is dissolved by hydrochloric acid to which is added
an oxydant for facilitating the combustion of the hydrogen in the hydrochloric
acid and the union of the chlorine of same with the tin so as to form 'chloride
of tin.
+1
.
I shall now as an example take clippings or pieces of waste tinned iron, but
it must be understood that the same process is applicable for extracting the tin
from other materials.
M
.
"
1:
"
My process is characterized by the relative proportions of the materials
applied and by the conditions under which they act and the order followed in
the operations.
As oxydants suitable for assisting the action of the hydrochloric acid I use
the nitrates or chlorates of commerce such as nitrate of sodium, chlorate of
potassium and the like.
These salts are employed under special conditions to be hereinafter described
and in the exact or approximately exact proportions derived from the reactions:
ог
"
6 Sn + 6 HC1 + KO.CIO = 6 SnCl + KC1 + 6 HỌ,
with the exception of a slight excess of hydrochloric acid which is indispensable
for compensating accidental losses and for maintaining the acidity of the
liquids.
The nitrate or chlorate required for dissolving the tin of say a tonne (194 cwt.)
of the waste pieces of "tin is first dissolved in about 1000 litres (220 gallons)
of water, the hydrochloric acid being then added and mixed.
14
The solution thus prepared is heated to at most to 30° C. (86° F). It is
especially essential not at first to raise the liquid to as high a temperature as
for instance 80° or 100° C. (176° or 212° F.) and further not to use an excess
of reagents; in fact an immediate raising of the temperature would produce the
elimination of a considerable part of the reagents by evaporation or decomposition
and would especially with an excess of reagents, favour redundant or unnecessary
reactions which would hinder the obtaining of the desired result.
The bath having been thus prepared a first lot of waste "tin' or clippings
is plunged into it. When the tin has been removed from it, the pieces of black
iron are taken away and a new charge is introduced into the bath and so on
while gently and gradually raising the temperature for stimulating' the dissolving
action, which offers no inconvenience as the liquid becomes poorer and poorer in
nitrate or chlorate.
I
...
T
The liquids resulting from this operation may be again replenished with hydro-
chloric acid and oxydant and cause a new operation exactly similar to the first and
so on until it is thought that the liquid'is sufficiently saturated with tin for the
use to which it is intended to be put. At this stage the liquids, after being

page_text: used up on the clippings or waste pieces, are treated by electrolysis or by one
or other of the processes for removing the tin.
The operating conditions which have just been described should be attended
with the greatest care because if from the beginning the liquids are subjected
to a too high temperature and especially in the presence of an excess of reagent,
the action becomes violent. The result is that not only is the coating of tin
dissolved but also a very large proportion of the iron at the same time that a
part of the acid reagents are eliminated in the form of gas or vapours in the
atmosphere as above mentioned. This process is therefore characterized not only
by the employment of special oxydants which are more economical for facilitating
the action of the hydrochloric acid on the tin, but also for the mode of
operation which if scrupulously followed gives very good results.
The nitrate or chlorate introduced into the dissolving bath plays the same role
there if this bath contains chloride of iron.
It does not matter much therefore if the bath contains perchloride of iron
proceeding from the bath having somewhat attacked the black iron of the tin
waste or if it be intentionally added. The use of the nitrates or chlorates as
oxydants presents, still further, the advantange of introducing the formation of
salts into the baths which render them better conductors of electricity which is
important if it is desired to precipitate the tin by electrolysis.
Dated the 25th day of September 1890.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
COMPLETE SPECIFICATION.
A Process for the Recovery of the Tin and the Iron from Waste
Pieces or Clippings of Tinned Sheet or other Iron or Steel.
I, CAMILLE LEON CHARLES BERTOU of 11 Rue de St. Pétersbourg Paris in
the Republic of France 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 refers to improvements in the mode of recovering the tin and the
iron or steel from waste pieces or clippings of tinned sheet or other iron or steel,
according to which the tin is dissolved by hydrochloric acid to which is added an
oxydant for facilitating the combustion of the hydrogen in the hydrochloric acid
and the union of the chlorine of same with the tin so as to form chloride of tin.
I shall now as an example take clippings of waste tinned iron but it must be
understood that the same process is applicable for extracting the tin from other
materials.
My improvements are characterized by the nature and relative proportions of the
materials in the bath and by the conditions under which they act and the order
followed in the operations.
As oxydants suitable for assisting the action of the hydrochloric acid I use the
nitrates or chlorates of commerce such as nitrate of sodium, chlorate of potassium
and the like.
These salts are employed under special conditions to be hereinafter described.
The best results are obtained by the proportions derived from the following
reactions.

page_text: The nitrate or chlorate required for dissolving the tin of say a "tonne" (19½ cwts.)
of the waste pieces of "tin" is first dissolved in about 1000 litres (220 gallons) of
water or in a smaller quantity of water and even down to about 500 litres, the
hydrochloric acid being then added and mixed.
The solution thus prepared is heated to a temperature between 30 and 50° C.
(86 to 112° F.) according to the degree of concentration of the liquids. It is
essential especially at first not to raise the liquid to as high a temperature as for
instance 80 or 100° C. (176 or 212° F.) and further not to use an excess of reagents,
in fact an immediate raising of the temperature would produce the elimination of
a considerable part of the reagents by evaporation or decomposition and would
especially with an excess of reagents, favor redundant or unnecessary reactions
which would hinder the obtaining of the desired result.
The bath having been thus prepared a first batch of waste "tin" or clippings is
plunged into it. When the tin has been removed from it the pieces of black iron
are taken away and a fresh charge is introduced into the bath, and so on while the
temperature is being gradually raised for stimulating the dissolving action, which
offers no inconvenience, as the liquid becomes poorer and poorer in nitrate or
chlorate.
The liquids resulting from this operation may be again replenished with hydro-
chloric acid and oxydant and cause a fresh operation exactly similar to the first,
and so on, until it is thought that the liquid is sufficiently saturated with tin for the
use to which it is intended to be put. At this stage the liquids after being used
up on the clippings or waste pieces are treated by electrolysis or by one or other of
the processes for removing the tin; but as the chemical treatment introduces into
the liquids a certain quantity of other metals than tin, it is useful, when it is desired
to obtain the tin in a pure state, to separate the said other metals therefrom, for
which purpose I employ the means described further on.
The operating conditions which have just been described should be attended to
with the greatest care because if from the beginning the liquids are subjected to a
high temperature and especially in the presence of an excess of reagents, the action
becomes violent, the result being that not only the coating of tin is dissolved but
also a very large proportion of the iron, at the same time that a part of the acid
reagents are eliminated in the form of gas or vapours escaping in the atmosphere as
above mentioned. My process is therefore characterized not only by the employ-
ment of special oxydants which are more economical for facilitating the action of
the hydrochloric acid on the tin but also by the mode of operation which if
scrupulously followed gives very good results.
The nitrate or chlorate introduced into the dissolving bath plays the same role
there if this bath contains chloride of iron.
It therefore matters little if the bath contains perchloride of iron resulting from
the bath having somewhat attacked the black iron of the tin waste or if it be
intentionally added. The use of the nitrates or chlorates as oxydants presents
moreover the advantage of inducing the formation of salts in the baths which
render them into better conductors of electricity which is important if it is desired
to precipitate the tin by electricity.
When as aforesaid the tin has to be separated from the other metals which follow
it in the bath I precipitate the same in the condition of oxyde by an alkaline
carbonate or an earthy alkaline carbonate and I prefer for this operation carbonate
of lime or carbonate of soda because of their cheapness and their light atomic weight.
In both cases it is convenient to add the carbonate gradually only and to cease
adding as soon as the oxyde of tin (which comes first) has been quite precipitated in
order not to precipitate in the form of oxyde or carbonate the iron, the zinc, the lead,
or the copper which may be contained in the liquids. When working with an alkaline
carbonate any analytical means will serve to indicate at what moment the
precipitation of the tin has been obtained; when precipitating with an earthy
alkaline carbonate every addition of the reagent will shew a disengagement of
carbonic acid, indicating that the tin has not vet been completely precipitated as

page_text: soon as no more gas comes off, the operation may be considered ended, and the oxyde
of tin has then only to be collected.
Evidently the operation may be begun with an earthy alkaline carbonate and
ended with an alkaline carbonate, or vice versâ; or these two reagents may be
employed at the same time without in reality changing the reactions because the
process I describe is based upon this fact that in the presence of metals such as iron
in the least quantity, zinc, lead or copper, the carbonates in the first place
precipitate the tin and that in the process described it is separated in the oxyde
form. The oxyde of tin is washed and collected and has now only to be transformed
into metal which is very easily done by following one of the known means for
extracting tin from its different minerals.
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. In the process for the recovery of the tin and the iron from waste pieces or
clippings of tinned sheet or other iron or steel by means of hydrochloric acid
together with an oxydant the method consisting in forming a dissolving bath con-
taining the proportions of reagents resulting from the equations hereinbefore named
and plunging thereinto successively the batches of waste pieces cold or slightly
heated according to the reagent employed then gradually heating, as the bath
becomes impoverished as to the reagent oxydants by the introduction of fresh
batches of waste pieces, and so continuing until the liquid has become quite exhausted
and then extracting the tin substantially as set forth.
2. In the process named the employment of a nitrate or a chlorate as an oxydant
in conjunction with hydrochloric acid for forming the solvent bath in the presence
or absence of chlorides of iron substantially as set forth.
3. In the process named the employment of an alkaline carbonate or an earthy
alkaline carbonate for precipitating the tin from its solutions, separating the other
metals also contained therein and obtaining thus oxyde of tin substantially as set
forth.
Dated this 25th day of June 1891
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.