An Improved Process for the Extraction or Reduction of Soft Metals, such as Tin or Lead, from Metallic Oxides or Dross.
Year: 1898

page_text: Date of Application, 20th Dec., 1898-Accepted, 1st Apr., 1899
An Improved Process for the Extraction or Reduction of Soft Metals,
such as Tin or Lead, from Metallic Oxides or Dross.
I, JOHN CHRISTOPHER TALIAFERRO, of the corner of Boston and Hudson Streets,
in the City of Baltimore, in the County of Baltimore, and State of Maryland,
United States of America, Manufacturer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
-
My invention relates to improvements in the art of recovering or reducing back
to pure metallic tin the tin oxide or dross which is produced in tinning or other
operations.
In the practical manufacture of tin plate a considerable amount of tin oxide or
dross is always produced, the same requiring to be skimmed off from time to time
from the top of the molten tin in the tinning pots or vessels. This tin oxide or
dross has heretofore resulted in a good deal of waste and adds materially to the
cost or expense of manufacturing tin plate. The process or method heretofore
generally employed for reducing the dross or tin oxide, or recovering the pure
tin therefrom, has consisted essentially in subjecting it to the action of reverbera-
tory furnaces; but this process is attended with a good deal of expense and con-
siderable waste, as the tin in part escapes and goes up the chimney in the form
of vapor in the high heat necessarily employed.
The object of my invention is to provide a simple and inexpensive means or
process of reducing tin oxide or dross to pure metallic tin, and without waste.
I have discovered that this important object or new result may be accomplished
by subjecting tin oxide or dross to the action of stearic acid or other fat acid and
a comparatively low degree of heat, preferably that of molten tin.
In practising my invention, I place the oxide or dross in a suitable pot or vessel
partly filled with molten tin, the vessel being subjected to a slow heat to keep
the tin in a molten condition, the molten tin thus serving to impart the required
degree of heat to the tin oxide or dross, and then cover the oxide or dross with a
fatty acid, preferably stearic acid, which, in connection with the heat, causes the
tin oxide or dross to be reduced or returned to pure metallic tin, while at the
same time the fatty acid covering the dross and tin prevents further oxidation
during the process, by excluding air from the surface of the molten metal. The
length of time required in the process, or for the fatty acid and heat to reduce the
tin oxide or dross back to pure metallic tin, is ordinarily only a few minutes and
the process is carried on without any waste or loss of material. The process is
exceedingly cheap or inexpensive, as the only cost is that of the fuel required
to maintain the low heat necessary to keep the tin in a molten condition.
My process may also be used in recovering or reducing solder dross or oxide, or the
lross or oxide produced from other alloys of tin, and also in reducing lead dross
back to metallic lead.

page_text: Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:-
1st. The process or improvement in the art of recovering or reducing tin oxide
or dross to metallic tin, consisting in collecting quantities of the oxide or dross
from tinning pots or other sources and subjecting it to the action of fatty acid and
a low heat in the presence of molten metallic tin, substantially as specified.
2nd. The process or improvement in the art of recovering or reducing tin
oxide or dross to metallic tin, consisting in collecting quantities of the oxide or
dross from tinning pots or other sources and subjecting it to the action of stearic
acid and a low heat in the presence of molten metallic tin, substantially as specified.
3rd. The process of reducing metallic oxide or dross from tin, lead, or alloys
thereof, consisting in collecting the oxides or dross in quantities from tinning
pots or other sources and subjecting them to the action of a fatty acid and a low
degree of heat in the presence of molten metal of the kind to be recovered, sub-
stantially as specified.
ባሰ
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.