AN IMPROVED METHOD FOR TREATING AND SEPARATING REFUSE METALS
Year: 1887

page_text: Date of Application, 24th Mar., 1887
Complete Left, 24th Dec., 1887
Complete Accepted, 24th Feb. 1888
I JOHN EDWARD TENISON WOODs of 83 Lombard Street in the City of London
Civil & Chemical Engineer do hereby declare the nature of my Invention for AN
IMPROVED METHOD FOR TREATING AND SEPARATING REFUSE METALS to be as follows:-
The object of this Invention is to separate from refuse metallic substances, such as
tin scrap, old cases for tea, preserved meats, vegetables, fish, milk and other cases used
to enclose edible and other substances, so as to separate the tin, lead, antimony and
other metals from the iron and to render the latter marketable for soft scrap.
The process I employ obviates the necessity for preliminary or other cleaning and
is by immersing the tins in a boiling solution of caustic soda or potash, preferably
caustic soda, which dissolves the whole of the tin, forming a stanate of soda or potash
and also dissolves the lead in the solder, forming plumbate of soda or potash, as the
case may be, entirely purifying the iron, which is left with a bright surface.
Should antimony or other metals belonging to that class be present, they will also
go into the solution with the lead or tin.
The lead can be separated from the solution in the form of white carbonate of lead,
by means of a current of carbonic acid and the tin can be recovered, either in the form
of a crystallised stanate (used in dying) or if preferred can be thrown down in the
metallic state, either by a positive metal, or by electric deposition.
The mother liquors, as it is not necessary to clean or purify the tins before
immersion in the alkaline solutions, will contain a certain amount of rough soap and
glycerine, due to the destruction of the oily, fatty, or animal matters, that always
adhere to these cases, or coverings in their disused state and which by the ordinary
process of recovering the tin by hydrocloric acids, must be first done away with.
Iron, copper, or porcelain boilers or vessels can be used for carrying out this
process and it is obvious, that the rough soap and glycerine can be recovered from the
mother liquors, after the inetals have been separated as above described.
London, March 24th 1887.

page_text: COMPLETE SPECIFICATION.
An Improved Method for Treating and Separating Refuse Metals.
I JOHN EDWARD TENISON WOODS 83 Lombard Street in the City of London and
40 Grove Hill Road Camberwell in the County of Surrey, Civil Engineer 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:
The objects of this invention are for "Improvements in processes for the Recovery
and Separation of Refuse Metals" and more particularly for the separation and
Recovery of the Tin, Solder and Sheet Iron from refuse Meat Tins Cans Sardine
boxes and other sheet tinned Iron Cases used for packing provisions and other similar
articles for domestic uses after the contents have been used and the cases thrown
away.
Tens of thousands of Tons of such refuse cases find their way to the Parochial dust
heaps and are usually entirely wasted.
Such tinned cases after delivery at the Works are in carrying out my improved
processes for recovery and separation of their metallic contents packed in the uncleaned
state in iron wire cages of suitable size and immersed in a boiling solution of caustic
Soda or potash contained in suitable iron or other vessels called No. 1 such solution
containing from half a pound to one pound of caustic Alkali to one Gallon of Water
and left there until all the paint, Varnish, grease, Oil, Animal matter, or other
impurities are dissolved and converted into rough soap afterwards collected.
The wire cage with its contents of cleaned tins or cases is then immersed in an iron
vessel called No. 2 with a cast iron bottom provided with a fire underneath. This
vessel is filled with melted caustic soda or potash containing about ten per cent. of
Nitrate of Soda and one per cent. of powdered peroxide of Manganese or such other
quantities of each or either of these materials as the circumstances of the case may
require (but preferably the quantities above named) maintained at a melting
temperature which is about 500 degrees Fahr. thermometer.
of
The cages with their tinned contents are aggitated in the hot liquid until the solder
of the joints of the Tins or cases has melted off and fallen to the bottom of the pan
this No. 2 and the Tin on the surface of the Tin plates has been converted into Stanate
and Stanite of Soda or potash which remains in solution. The Cages containing the
cleaned sheet iron which formed the basis of the tinned cans or cases are washed in a
vessel of hot water called No. 3 to remove the adhering caustic Alkali which can be
subsequently recovered by evaporating the solution. The cleaned iron sheet can then
be pressed together in any suitable contrivance and sent to the Rolling Mills for
reheating, rolling and remanufacture into new Sheet Iron. When the vessel called
No. 2 and its melted contents of Alkaline Stanites and Stanates should be sufficiently
rich in tin to contain one half its weight of that metal the contents are put into a
large iron or other vessel and dissolved in a large quantity of hot water and the Oxide

page_text: of Tin thrown down by milk of lime or any other precipitant of by means of an
electric current as metallic Tin.
The Oxide of Tin or the metallic tin as the case may be is smelted or melted in the
usual way and run into Ingots for market.
The solder which will have collected at the bottom of No. 2 Vessel can be removed
when the Vessel is cleaned out and cast into suitable molds for reuse.
The surplus solution of Alkali from which the Tin or Oxide of Tin has been
precipated is evaporated and used again.
The rough soap floating on the top of No. 1 Vessel produced by the combination of
the Alkaline solution with the Oil, fat, grease, Varnish, or other such impurities
originally existing on the raw Tins or Cases or otherwise combined in the fluid is
separated in the usual way as in Soap making as is valuable for any of the purposes
to which soap is now applied and can be especially used in the manufacture of Railway
Axle Grease or for fulling or other such purpose.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is
The Recovery and Separation of Refuse Metals (and more particularly the
utilization of refuse tins, cans and Cases) by the processes above described being
practical methods of doing the same not hitherto in use, by which valuable but hitherto
waste material of the above description can be made again valuable.
London 24th December 1887.