IMPROVE- MENTS IN PRECIPITATING METALLIC COPPER FROM ITS SOLUTIONS, AND IN OBTAINING A UTILIZABLE MATERIAL FROM THE AGENT EMPLOYED FOR THE PURPOSE
Year: 1874

page_text: LETTERS PATENT to John Thomson Duncan, of Glasgow, in the County
of Lanark, Scotland, Accountant, for the Invention of "IMPROVE-
MENTS IN PRECIPITATING METALLIC COPPER FROM ITS SOLUTIONS, AND IN
OBTAINING A UTILIZABLE MATERIAL FROM THE AGENT EMPLOYED FOR THE
PURPOSE." A communication from abroad by Thomas Sterry Hunt,
of Boston, Massachusetts, in the United States of America.
Sealed the 31st July 1874, and dated the 12th February 1874.
PROVISIONAL SPECIFICATION left by the said John Thomson Duncan
at the Office of the Commissioners of Patents, with his Petition,
on the 12th February 1874.
I, JOHN THOMSON DUNCAN, of Glasgow, in the County of Lanark,
Scotland, Accountant, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN PRECIPITATING METALLIC COPPER FROM ITS SOLUTIONS,
AND IN OBTAINING A UTILIZABLE MATERIAL FROM THE AGENT EMPLOYED FOR THE
PURPOSE," communicated to me from abroad by Thomas Sterry Hunt,

page_text: IОHOWS:-
According to this Invention waste tinned iron plate, called also tin
plate scrap or waste, is used for precipitating metallic copper from its
solutions, and the tin is recovered so that it may be utilized.
The tin plate scrap or waste is used for the precipitating of copper
from the solutions obtained in the various wet processes of copper
extraction. The copper solutions must contain at the same time proto-
chloride of copper (called also cupric chloride) and sulphate of soda, or
of some other base. Such solutions are obtained from sulphuretted
copper ores which have been calcined with common salt as in the Long-
maid or Henderson process, or when similar ores, after roasting, are
digested with chlorides of iron or other soluble chlorides, as, for
example, in Hunt and Douglas' Patent process. In case, however, the
solution of copper to be precipitated contains no chlorides a portion of
common salt is added, and in case it contains no sulphates a portion of
sulphate of soda is added or other soluble sulphate; in either case these
salts may equal the amount of copper present. Such solutions contain-
ing chlorides and sulphates, especially if heated, as is usual in copper
precipitation, quickly dissolve the tin from tinned iron plate when
immersed therein, and at once let it fall again as an insoluble hydrated
oxide of tin, which may be readily drawn off while suspended in the
liquid and collected by subsidence in tanks to be subsequently treated
by well known methods, such as dissolving in hydrochloric acid and
precipitating by metallic zinc by reduction in the dry way or conversion
into stannate of soda. The scrap iron freed from tin is then employed
in the ordinary way to precipitate the dissolved copper as metallic or
ecment copper from the solutions described. The copper solution hold-
ing the suspended oxide of tin may be drawn off at once from the iron
to the settling tank and a fresh solution added, or the precipitation of
the copper may be carried on without intermission in the first solution
till this is exhausted and the oxide of tin afterwards separated from the
metallic copper by taking advantage of its greater lightness and its
finely divided state. If the tin may be removed from the iron plate
without causing an immediate precipitate of copper a solution of per-
chloride or other per-salt of iron is mixed with the copper solution.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Thomson Duncan in the Great Seal Patent
Office on the 11th August 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THOMSON DUNCAN, of Glasgow, in the County of Lanark, Scotland,
Accountant, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of February, in the year of our
Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Thomson Duncan, Her special
licence that I, the said John Thomson Duncan, my executors, adminis-
trators, and assigns, or such others as I, the said John Thomson
Duncan, my executors, administrators, and assigns, should at
any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, excrcise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN PRECIPITATING METALLIC COPPER FROM ITS SOLUTIONS, AND
IN OBTAINING A UTILIZABLE MATERIAL FROM THE AGENT EMPLOYED FOR THE
PURPOSE," communicated to me from abroad by Thomas Sterry Hunt, of
Boston, Massachusetts, in the United States of America, upon
the con-
dition (amongst others) that I, the said John Thomson Duncan, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Thomson Duncan, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :—
The Invention relates to a new use and application of refuse, waste,
or scrap tinned sheet iron, commonly known as tin plate, the tin plate

page_text: scrap or waste is used for precipitating copper from its solutions, and the
tin is recovered so that it may be utilized, that is to say :-
This Invention consists in using tin plate scrap or waste for the pre-
cipitation of copper from the solution obtained in the various wet
processes of copper extraction, and in saving in the process the adhering
tin. The copper solutions must contain at the same time proto-chloride
of copper (called also cupric chloride) and sulphate of soda, or of some
other base. Such solutions are obtained from sulphuretted copper ores
which have been calcined with common salt, as in the Longmaid or
Henderson process, or when similar ores, after roasting, are digested
with chlorides of iron or other soluble chlorides, as, for example, in
Hunt and Douglas' Patent process. In case, however, the solution of
copper to be precipitated contains no chlorides a portion of common salt
is added, and in case it contains no sulphates a portion of sulphate of
soda is added, or other soluble sulphate; in either case these salts may
equal the amount of copper present. Such solutions containing chlorides
and sulphates, especially if heated, as is usual in copper precipitation,
quickly dissolve the tin from tinned iron plate when this is immersed
therein, and at once let it fall again as an insoluble hydrated oxyde of
tin, which may be readily drawn off while suspended in the liquid, and
collected by subsidence in proper tanks to be subsequently treated by
methods well known to chemists, such as dissolving in hydrochloric acid
and precipitating by metallic zinc, by reduction in the dry way, or by
conversion into stannate of soda. The scrap iron thus freed from tin is
then employed in the ordinary way to precipitate the dissolved copper
as metallic or cement copper from the solutions described. The copper
solution holding the suspended oxide of tin may be drawn off at once
from the iron to the settling tank and a fresh solution added, or the
precipitation of the copper may be carried on without intermission in
the first solution till this is exhausted and the oxide of tin afterwards
separated from the metallic copper by taking advantage of the greater
lightness and the more finely divided state of the former. Should it be
desirable to remove the tin from the iron plate without causing an
immediate precipitation of copper, a solution of perchloride, or other
per-salt of iron is mixed for the purpose with the copper solution.
I do not claim the use of iron for precipitating copper from its
solutions nor the modes of treating the separated oxyde of tin, nor

page_text: any particular arrangement of apparatus for the operation above.
described.
Having now described the nature of the said Invention, and in what
manner the same may be performed, I declare that I claim,-
First. The use and application of tin plate scrap or waste for
precipitating metallic copper from its solutions, substantially as above
described.
Second. The recovery and utilization of the tin from the tin plate
scrap or waste by means of its solution and subsequent precipitation as
oxyde of tin in solutions containing proto-chloride of copper and a
sulphate, substantially as above described.
In witness whereof, I, the said John Thomson Duncan, have
hereunto set my hand and seal, this Eighth day of August, in
the year of our Lord One thousand eight hundred and seventy-
four.
Witness,
JAB. HENDERSON.
J. THOMSON DUNCAN. (L.S.)