IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE IRON, AND IN TREATING OTHER PRODUCTS OBTAINED IN THE PROCESS
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
SCHUNCK, of Rochdale, in the County of Lancaster, Chemist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Twenty-ninth day of November, in the twelfth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Edward Schunck, Her especial license, full power, sole privilege
and authority, that I, the said Edward Schunck, my exors, adññiors, and
assigns, and such others as I, the said Edward Schunck, my exors, adiñiors,
or assigns, should at any time agree with, and no others, from time to time
and at all times during the term of years therein mentioned, should and
lawfully might make, use, exercise, and vend, within England, Wales, the
Town of Berwick-upon-Tweed, and in all Her Majesty's Colonies and Plan-
tations abroad, and in the Islands of Jersey, Guernsey, Alderney, Surk;
and Man, my Invention of "IMPROVEMENTS IN THE MANUFACTURE OF MALLEABLE
IRON, AND IN TREATING OTHER PRODUCTS OBTAINED IN THE PROCESS;" in which
said Letters Patent is contained a proviso obliging me, the said Edward
Schunck, by an instrument in writing under my hand and seal, particularly
to describe and ascertain the nature of my said Invention, and in what
manner the same is to be performed, and to cause the same to be inrolled
in Her Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: NOW KNOW YE, that in compliance with, the said proviso, I, the said
Edward Schunck, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, is particularly described
and ascertained in and by the following description thereof (that is to say):-
The first part of my Invention relates to the manufacture of malleable
iron from tin plate scrap, which scrap consists of thin strips of plate iron
covered with tin, being the refuse and clippings obtained-in-the manufacture
of articles from tin plate, or old articles of the same material rendered
useless by wear. The presence of the tin has hitherto rendered tin plate scrap
unfit for the manufacture of iron, and I propose to remove perfectly the
whole of the tin from the surface of the plate before I begin to manufacture
the scrap into malleable iron. By any one of the following processes I effect
the separation of the tin of the plate scrap from the plate iron so as to render
the iron plate applicable to the manufacture of malleable iron, viz. :-I place the
tinned plate scrap in a boiling or hot solution of an alkaline sulphuret con-
taining an excess of sulphur; and of this class of substances I prefer the per-
sulphuret of sodium made by dissolving sulphur in a solution of caustic soda,
or by fusing sulphur with carbonate of soda, or by any of the other well-known
methods of producing persulphuret of sodium. The excess of sulphur in this
persulphuret changes the metallic tin into a sulphuret of tin, which sulphuret
of tin dissolves by means of the sulphuret of sodium deprived of its excess of
sulphur, forming a compound variously denominated by chemists as stannosul-
phuret of sodium and sulphostannate of sodium. By this process the iron is
rendered perfectly free from the coating of tin.
Or, instead of the above process, I place the tinned scrap in a solution of
oxide of lead in caustic potash or soda ley. During this process the tin
becomes converted by the action of the oxide of lead in the solution into
oxide of tin, which dissolves in the caustic potash or caustic soda, forming
stannate of potash or stannate of soda, while metallic lead is precipitated from
the solution in the shape of a black powder. It is immaterial, as far as regards
the ultimate effect, whether the solution of oxide of lead in caustic potash or
soda ley be employed in a boiling state, or merely warm or cold, but the
process goes on with much greater speed when the solution is employed at a
temperature nearly approaching ebullition than when cold; by this process the
iron is obtained nearly free from tin.
Again, instead of either of the foregoing processes, I place tinned scrap in a
solution containing a chromate of an alkali and caustic alkali, when the
metallic tin becomes converted by means of the chromic acid of the alkaline
,chromate into oxide of tin, which dissolves in the excess of alkali, forming a

page_text: stannate, of the alkali, while chromic oxide is precipitated, and the iron is left
nearly free from tin. Of these processes I prefer the first, in consequence of
the inconvenience experienced from the precipitated metallic lead of the second
process, and the precipitated chromic oxide of the third.
4
The iron, deprived of its coating of tin by any of the above processes, I
wash well with water in order to remove the excess of the solutions employed
which may adhere to it, and in case the second or third processes are used in
order to remove the precipitated metallic lead or precipitated chromic oxide
mechanically adhering to it. After allowing the liquor to drain off I find it
convenient to pack the pieces of scrap iron closely in cylinders or pipes of sheet
iron, each pipe having a capacity of about one cubic foot, and being made to
contain; by means of a slight degree of compression, about eighty pounds
weight of material; a pipe thus filled with scrap iron I place in the fire, and
when it is red hot or at a welding heat, I remove it from the fire and hammer
the mass while hot in the way usually employed for making bar iron, and I.
repeat the process of heating in the fire and hammering while hot until the
whole mass becomes uniformly solid.
I claim under this part of my Invention the use of alkaline sulpburets of
solutions of oxide of lead in caustic alkalies, and of the chromates of alkalies
with caustic alkalies, for the separation of the tin from the tinned iron plate.
And I claim the use of iron obtained from tinned iron scrap by any of the
above processes for the manufacture of malleable iron.
The second part of my Invention relates to the recovery of the tin from the
solutions employed for separating it from the iron, as described in the first part
of my Invention.
The alkaline stannosulphuret, obtained by the process first described, is
very soluble. I boil down the solution in iron vessels until a drop crystallizes
on cooling; I then allow the whole to crystallize. I drain the crystals on
strainers made of iron wire gauze; I then put the crystals in a press and
squeeze out as much of the liquid contained in the interstices between
them as possible; I then place them in a reverberatory furnace, such
as is generally used for the smelting of tin ores. By the application of
a low heat in this furnace I dry the crystals completely, and then slowly
roast them, by which means the sulphur of the sulphuret of tin is partly
driven off and partly burnt, the sulphuret being changed thereby into
oxide of tin; I then throw on the roasted mass a mixture of small coal,
charcoal, or any other carbonaceous substance, with dry carbonate of
soda or quick lime, and the heat being then raised in the furnace the
oxide of tin is reduced, and I obtain metallic tin, which I allow to run off

page_text: in a molten state through a hole at the bottom of the furnace. The slack
which is left in the furnace I rake out, and as it consists principally of
alkaline sulphuret, I dissolve it in water, and after adding fresh sulphur to it
I use it again for stripping fresh quantities of scrap from its metallic tin.
The solution of alkaline stannate obtained by the second and third processes
I boil down in iron vessels until crystals of the alkaline stannate are deposited,
which crystals, while they form, I remove by means of an iron scoop per-
forated with holes, and place them as before on iron wire gauze strainers to
drain; I then press them, mix them while still moist with small coal, charcoal,
or any other carbonaceous substance, and place them in a reverberatory
furnace. By the application of heat in the usual way I obtain metallic tin,
which is drawn off as before. The slack consists in this case principally of
carbonate of soda, and I therefore dissolve it in water, render it caustic by
means of quick lime, and by adding to it either oxide of lead or an alkaline
chromate I obtain a liquor adapted for stripping the tin from fresh quantities
of tinned plate as before.
I claim under this part of my Invention the use of sulphurets and oxides
of tin obtained from refuse or scrap tin plate (by any of the processes above
described) for the purpose of obtaining from such sulphurets or oxides
metallic tin, or for any other purpose to which such sulphurets or oxides may
be applicable.
In witness whereof, I, the said Edward Schunck, have hereunto set
my hand and seal, this Nineteenth day of May, in the year of our
Lord One thousand eight hundred and forty-nine.