IMPROVEMENTS IN EXTRACTING COPPER FROM ITS ORES
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Arthur Hornby Lewis at the
Office of the Commissioners of Patents, with his Petition, on the
15th February 1869.-A communication from abroad by Thomas
Sterry Hunt, of Montreal, and James Douglas, junior, of Quebec,
both in the Dominion of Canada.
I, ARTHUR HORNBY LEWIS, of the Firm of James Lewis and Son,
of Fenwick Street, Liverpool, in the County of Lancaster, Merchants,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
EXTRACTING COPPER FROM ITS ORES," communicated to me from abroad by
Thomas Sterry Hunt, of Montreal, and James Douglas, junior, of
Quebec, both in the Dominion of Canada, to be as follows:-
For the extraction of copper from its ores by this process it is necessary
that it should be in a state of protoxyd or suboxyd or some compound of
one of these oxyds. Sulphuretted ores are therefore pulverized and
thoroughly roasted or calcined in contact with air in a suitable furnace, as
a reverberatory, muffle, or terrace furnace, from which the sulphurous
àcid produced may be collected to be made use of in the production of
sulphuric acid or for the treatment of oxychlorid of iron, as herein-after
described. For the native oxydized oros, such as the black and rod

page_text: oxyde, the carbonates and oxychlorides of copper, calcination is not
necessary but they must be finely pulverized. The pulverized and
naturally or artificially oxydized ores are then digested with a watery
solution of a protosalt of iron, either with or without an addition of
earthy or alkaline chlorid, preferring the neutral protochlorid of iron, t
which may be conveniently prepared for the purpose by one of the
following methods, viz. :-
1. By saturating hydrochlorid acid with metallic fron or nativo
carbonate of iron or by saturating the said acid with native or artificial
oxyd of iron, or with the oxychlorid produced in a subsequent part of 1
this process, and afterwards reducing the higher chlorid thus formed
by digestion with metallio iron.
2. By double decomposition of protosulphate of iron (green copperas)
with an equivalent of a soluble chlorid, as chlorid of calcium or chlorid
of sodium.
..... By the action of metallic iron on the dichlorid of copper.
.:!
4. By the reducing action of sulphurous acid on the oxychlorid of
iron,
1
By the action of a solution of protochlarid of iron on the oxyds of
eopper and the above-mentioned compounds of the oxyds of copper 2
these are converted into dichlorid of copper, which is readily soluble in
eoncentrated solutions of the earthy or alkaline chlorids, such as
common salt, at the same time the iron separates from the solution as
an insoluble oxychlorid.
To apply this reaction to the extraction of copper protochlorid of 2
fron is prepared by one of the methods 1 and 2, according as hydro-
chlorid acid or copperas is cheaper or more available. Green copperas
and common salt, or dry chlorid of calcium, or hydrated chlorid, are
dissolved in water or protochlorid of iron prepared by one of the other
methods mentioned, and containing iron. To the solution common salt a
is added,
The pulverized and oxydized copper ores, prepared as above, are
digested with the liquid just described with agitation from time to
time, Heat, though not necessary, hastens the solution of the copper.
When the solution is complete the liquid is drawn off and the residue
lixiviated with a small portion of brine. The united liquids are then
digested with metallic iron by which the copper is thrown down as

page_text: cement copper. To the bath thus freed of copper it is necessary before
using it to dissolve the oxyd of copper from a second. portion of ore to
add protosulphate or protochlorid of iron to restore the bath to its
original force. When advisable the oxychlorid of iron formed in the
above reaction may be economised by treating it with sulphurous acid,
by which it is converted into a mixture of soluble protochlorid and
protosulphate of iron. For this purpose the residue after the solution
of the copper may be exposed to sulphurous acid gas from the roasting
of sulphuretted ores and subsequently lixiviated with strong brine; or
the dissolving of the oxide of copper, and the conversion of the
oxychlorid of iron, may be carried on simultaneously as follows:-The
oxydized copper ore is added to a hath of protochlorid or other protosalt
of iron used with earthy or alkaline chlorid and digested with agitation
in contact with a current of sulphurous acid gas. In this way the
oxychlorid is decomposed as soon as formed, and the regenerated
protosalts of iron serve to chloridize fresh portions of oxyd of copper.
In this modification, by which a large amount of dichlorid of copper
is formed, a portion of it separates in a solid state and may be dissolved
by hot strong brine which deposits a large part of it on cooling, so
that the same brine may be used again and again by heating and
cooling each time. The solid dichlorid of copper is rapidly reduced to
the metallis state by iron, especially when moistened with brine. To
prevent the partial precipitation of copper from the dichlorid solutions
in the air it is well to have a small portion of protochlorid of iron
present. A little sulphurous aold gas will also prevent such pre-
cipitation. The accumulation of sulphate of soda in cases where proto-
sulphate of iron is used may be prevented by the use of chlorid of calcium,
which separates the aulphate as gypsum,
When sulphurous acid is employed to act upon the oxychlorid of iron
protochlorid of iron and sulphate of soda will accumulate in the bath
and may be removed by adding (from time to time) to a portion so
much lime in form of milk of lime as may be necessary to precipitate
the fron in that portion. After standing the clear liquid is drawn off
and added to the remainder of the solution, when the greater part of
the sulphate will be precipitated and the bath restored to its first
condition.
The main features of the Invention comprise the use of a solution of
neutral protochlorid of iron on of mixtum containing

page_text: oxyd or suboxyd of copper or their compounds into dichlorid of copper;
the use of sulphurous acid for decomposing the oxychlorid of iron
formed in the preceding reaction; and the process of extracting copper
from its oxydised ores by aid of the first or first and second of these
reactions.