TREATING WASTE OR SCRAP TINNED IRON AND WASTE OR SCRAP IRON IN ORDER TO OBTAIN VALUABLE PRODUCTS THEREFROM."
Year: 1880

page_text: LETTERS PATENT to Benjamin Biggs, of No. 3, Laurence Pountney Hill, in
"IMPROVEMENTS IN
the City of London, Merchant, for an Invention of
TREATING WASTE OR SCRAP TINNED IRON AND WASTE OR SCRAP IRON IN
ORDER TO OBTAIN VALUABLE PRODUCTS THEREFROM."
PROVISIONAL SPECIFICATION left by the said Benjamin Biggs at the
Office of the Commissioners of Patents on the 24th January 1880.
BENJAMIN BIGGS, of No. 3, Laurence Pountney Hill, in the City of London,
Merchant. "IMPROVEMENTS IN TREATING WASTE OR SCRAP TINNED IRON AND
WASTE OR SCRAP IRON IN ORDER TO OBTAIN VALUABLE PRODUCTS THEREFROM."
My Invention consists of the process or combination of processes hereinafter
described, whereby the coating of tin on waste tin plates or waste tinned iron is
separated from the iron and obtained in a valuable form, and the iron or ordinary
scrap iron is converted into oxide of iron in forms suitable for use for colouring and
polishing purposes, and for the purification of coal gas.
In treating waste or scrap tinned iron according to my Invention I dissolve it
in sulphuric acid, hydrochloric acid, nitric acid, or other suitable acid, or partly in
one acid and partly in another acid, and I precipitate the tin from the solution by
means of sulphuretted hydrogen, and remove the precipitate (sulphide of tin) and
dissolve it in hydrochloric acid, and then precipitate the tin from the solution with
zinc. Or I evaporate and crystallize the solution of chloride of tin.
After removing the precipitate of sulphide of tin from the solution of tin and
iron, as hereinbefore described, I add to the remaining solution ammonia or
carbonate of ammonia in the form of vapour or otherwise. This I prefer to do by
distilling ammoniacal liquor (gas liquor), and passing the vapour or the distillate
into the said solution, the vapour from the said ammoniacal liquor being purified
before condensation by passing it through lime or oxide of iron or in any suitable
way. The greater part of the iron is thus precipitated in the form of oxide or
carbonate, and the ammonia combining with the acid forms sulphate, or muriate, or
nitrate, or other salt of ammonia according to the acid used. I then remove the
precipitate, and if it be not in the form of a peroxide of iron, I convert it into a

page_text: peroxide by exposing it to the action of the atmosphere, and if the said peroxide be
required in an anhydrous form I heat it either in crucibles or in a suitable furnace.
The hydrated oxide is in a form suitable for use in the purification of coal gas.
In the anhydrous form it is suitable for use in polishing glass or other substances
or as a pigment.
In order to precipitate the iron remaining in the solution I add to it sulphide of
ammonium, and I remove the precipitate which is a sulphide of iron, and may be
used for purposes for which sulphide of iron is employed..
The remaining solution is a salt of ammonia corresponding to the acid used, and
this I concentrate or crystallize in order to bring it into a marketable state.
In treating ordinary untinned scrap iron I dissolve it in a suitable acid, and
treat the solution as herein before described with respect to the solution of tinned
iron after the removal therefrom of the precipitate of tin.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Benjamin Biggs in the Great Seal Patent Office on the 2nd July
1880.
BENJAMIN BIGGS, of No. 3, Laurence Pountney Hill, in the City of London;
Merchant. "IMPROVEMENTS IN TREATING WASTE OR SCRAP TINNED IRON AND
WASTE OR SCRAP IRON IN ORDER TO OBTAIN VALUABLE PRODUCTS THEREFROM."
In treating waste or scrap tinned iron according to my Invention I dissolve it in
sulphuric acid, hydrochloric acid, nitric acid, or other suitable acid, or partly in
one acid and partly in another acid; I prefer to use dilute sulphuric acid, to
which is added about one per cent. of nitric acid, and I precipitate the tin from
the solution by means of sulphuretted hydrogen. This precipitation I term No. 1
process; I remove the precipitated sulphide of tin, which I then dissolve in
hydrochloric acid, and precipitate the tin from the solution with zinc. Or I
evaporate and crystallize the solution of chloride of tin.
After removing the precipitate of sulphide of tin from the solution of tin and
iron, I add to the remaining solution ammonia or carbonate of ammonia in the form
of vapour or otherwise by distilling ammoniacal liquor (gas liquor), and purifying
the vapour by passing it through lime or oxide of iron, or as hereinafter described,
and passing the purified vapour or the distillate into the acid solution. By this
process (which I term No. 2 process) the greater part of the iron is precipitated in
the form of oxide or carbonate, and the ammonia combining with the acid forms
sulphate, or muriate, or nitrate, or other salt of ammonia according to the acid
used. I then remove the precipitate, and if it be not in the form of a peroxide I
convert it into a peroxide by drying it and exposing it to the action of the
atmosphere, and if the said peroxide be required in an anhydrous form I heat it in
crucibles, or in a reverberatory furnace or other suitable furnace. Should the
precipitate of oxide of iron contain any basic salts I sometimes prefer to treat it
with an alkali to decompose them before heating the precipitate.
The dried hydrated oxide is in a form suitable for use in the purification of coal
gas. In the anhydrous form the oxide is suitable for use in polishing glass or
other substances, or as a pigment.
After removing the precipitate obtained by No. 2 process I pass into the
remaining solution the vapour from crude ammoniacal liquor, which vapour con-
taining sulphide of ammonium precipitates the remaining iron as a sulphide of iron,
and being purified by passing through the solution is rendered fit for use in
process No. 2, and may be driven over and passed into a solution of iron, or of
tinned iron from which the tin has been precipitated by No. 1 process.
In treating ordinary untinned scrap iron I dissolve it in a suitable acid and
treat the solution as herein before described with respect to the solution of tinned
iron after the removal therefrom of the precipitate of tin, that is to say, in this case
No. 1 process is unnecessary.
By the means or process herein before described I obtain valuable products from
the scrap or waste metal in addition to the salt of ammonia ordinarily obtained by
passing the vapour from crude gas liquor into acid, and without material increase
of cost or labour.
Having now described the nature of my Invention and the manner in which it
is to be performed I claim as my said Invention,―
Dissolving waste or scrap tinned iron, or waste, or scrap iron in an acid or acids
and precipitating the iron from the solution by passing into it ammonia or

page_text: carbonate of ammonia produced by distilling ammoniacal liquor and purifying the
vapour therefrom, the tin in the case of tinned iron being precipitated and removed
before passing the ammonia or carbonate of ammonia into the solution.
In witness whereof, I, the said Benjamin Biggs, have hereunto set my hand
and seal, this Twenty-first day of July, in the year of our Lord One
thousand eight hundred and eighty.
BENJAMIN BIGGS. (LS)