IMPROVEMENTS IN THE TREATMENT OF ORES AND MINERALS CONTAINING COPPER TO EXTRACT COPPER THEREFROM
Year: 1868

page_text: LETTERS PATENT to Robert Oxland, of Compton Gifford, Plymouth,
in the County of Devon, for the Invention of "IMPROVEMENTS IN
THE TREATMENT OF ORES AND MINERALS CONTAINING COPPER TO EXTRACT
COPPER THEREFROM."
Sealed the 9th October 1868, and dated the 15th April 1868.
PROVISIONAL SPECIFICATION left by the said Robert Oxland at
the Office of the Commissioners of Patents, with his Petition, on
the 15th April 1868.
I, ROBERT OXLAND, of Compton Gifford, Plymouth, in the County of
Devon, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE TREATMENT OF ORES AND MINERALS CONTAINING COPPER TO EXTRACT
COPPER THEREPROM," to be as follows:--
To treat ores and minerals containing copper associated with sulphur
and other volatile substances, such as arsenic and antimony, with hydro-
chloric acid, or soluble metallic chlorides in the manner herein-after
described for extraction of the copper, I calcine the ores or minerals
above described in suitable furnaces for the removal of the greater part

page_text: of the sulphur and arsenic, and grind the calcined product to a fine
powder; with this I mix muriatic acid or a solution of chloride of iron
with other metallic chlorides, such as is obtained in the subsequent
process of lixiviation of the calcined ore. I slowly dry the mixture in
a calcining furnace having by preference two or more beds, and by
advancingthe mixture from the back bed farthest from the fire the heat
is gradually increased to dull redness. I continue the calcination with
free access of air until all or nearly all volatile matters are evolved, such
as the remaining sulphur and arsenic and some of the chloride of iron.
The charge drawn from the furnace while still hot I lixiviate with
boiling water acidulated with muriatic acid, continuing the lixiviation
until all the copper is extracted from the ore. The solution obtained by
this lixiviation I first treat with milk of lime to neutralize the excess
of acid necessary for the solution of the metallic matters, and then
precipitate the copper by digesting the solution on metallic iron. The
solution of chloride of iron associated with other metallic chlorides
obtained by this process affords the necessary supply of material for the
treatment of successive portions of calcined ore.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Oxland in the Great Seal Patent Office on
the 13th October 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
OXLAND, of Compton Gifford, Plymouth, in the County of Devon, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of April, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Robert Oxland, Her special licence
that I, the said Robert Oxland, my executors, administrators, and
assigns, or such others as I, the said Robert Oxland, 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, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the

page_text: Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE TREATMENT OF ORES AND MINERALS CONTAINING COPPER TO EXTRACT
COPPER THEREFROM," upon the condition (amongst others). that I, the
said Robert Oxland, my executors or administrators,, by an instru-
ment 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 immediately after the date of the said Letters
Patent..
NOW KNOW YE, that I, the said Robert Oxland, 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 :-
My Invention relates to the treatment of such ores and minerals as
contain copper associated with sulphur, and my Invention has for its
object the extraction of the copper more completely and at less cost
than by the ordinary course of smelting operations.
Copper ores containing sulphur I divide into two classes, 1st, those
which contain copper associated with sulphur in such small proportions
as not to be available for the manufacture of sulphuric acid, by burning
in kilns, or which if containing a large proportion of sulphur, yet from
being associated with arsenic or other volatile substances is unsuited
for the manufacture of sulphuric acid. 2nd, such ores as contain copper
so associated with sulphur as to allow of their being used for the
manufacture of sulphuric acid.
The processes I adopt are as follows:-Using the first class ores I
subject them to calcination, either in kilns or in suitable calcining
furnaces according to their condition and quality. If the ore contain
a sufficient quantity of sulphur to burn of itself, and is massive, I
reduce it to the average size of about a two-inch cube, and burn the
ore in kilns, such as are usually employed in the manufacture of
sulphuric acid, leading the products of combustion, through, suitable
condensing flues for the deposition of arsenic and any other metallic.
matters that may have been volatilized. If the ore do not contain
sufficient sulphur to burn of itself I mix with it other ores sufficiently
rich in sulphur to supply the deficiency; or if such be not obtainable,.
I make up the deficiency by mixing with it sufficient coal, preferably

page_text: anthracite. If this class of ore be obtainable only in the form of coarse
or fine powder the calcination should be carried on in furnaces; a
reverberatory furnace is suitable. The second class ores may be treated
by calcination in furnaces, or burning in kilns in the usual manner
adopted for the manufacture of sulphuric acid from iron pyrites. In both
cases the object to be sought is as complete a separation of sulphur
and of other volatile matters as may be effected by calcination and
oxidation of the constituents of the ores. The calcined products obtained
I prefer to grind to fine powder. Having provided a series of vats with
false bottoms I charge one of them with a quantity of the ground
calcined ore previously heated sufficiently to make the hydrochloric
acid to be run on it of about 212° Fahrenheit. Sufficient of the acid
is run on the charge to cover it to the depth of three inches. I allow.
the acid to stand on it about an hour, and then run the liquid off
slowly from the under side of the false bottom of the vat, and continue
the supply of hot acid on the top until I find that the solution running
off no longer contains any copper. The false bottoms of the vats are
perforated at and about the centre, and the perforated part is covered
with a little coarser ore to keep back the fine material. The vats should
be so arranged that the liquor running off should pass successively
through each one of the series as long as it may be found that the
proportion of copper in the solution is being increased. Finally the
clear liquor is run off into a receiver, where it is left to cool, so as to
allow of the deposition of any chloride of lead present. From this
receiver the liquor is run off through a filter to render the solution
bright and clear into the precipitating vat, where the copper is rapidly
precipitated by keeping the solution hot in contact with metallie iron.
It should be so arranged that a steady slow stream of liquor exhausted
of copper should be running off replaced by a like stream of liquor
containing copper entering at the top of the vat. This spent liquor
containing chloride of iron and other chlorides is reserved for further
use, as herein-after stated, instead of muriatic acid in subsequent charges.
The whole of the soluble copper having been removed from the ore in
the first vat of the series the acid left on the ore should be run off and
supplied to the next vat in the series, and so on. To economize acid
I usually wash the ore after the acid has been run off with the spent
chloride of iron liquor so as to displace the acid for further use and leave
the ore saturated with the spent liquor. The ore is then removed from

page_text: the vat with the adhering acid or spent liquor, as the case may be, and
put into a reverberatory furnace which has two or more beds. It is
dried on the back bed of the furnace farthest from the fire, and is stirred
from time to time to prevent caking, and if necessary (that is to say,
if by the examination of a sample it is found that all the copper has not
yet been rendered soluble) a further quantity of the spent liquor or
solution of chloride of iron with other chlorides is run on it and the
whole dried down, or muriatic acid may be used in place of the spent
liquor. The heat should not be more than sufficient to dry the charge
slowly, so as to effect as completely as possible the conversion of the
copper into chloride. When dry the charge is turned down to the next
bed, and thence (supposing the furnace to have three beds) to the one
nearest the fire, where it should be brought up to a dull red heat and
maintained at that temperature with constant stirring until no more
acid vapors are evolved or chloride of iron volatilized. The matters
volatilized in the furnace may be condensed by passing them through
the tower ordinarily used for the condensation of muriatic acid in the
manufacture of salt cake. The charge is then drawn from the furnace
and subjected while hot to another lixiviating process with hot water
acidulated with muriatic acid, and thereby the whole of the copper
contained in the ore may be removed in solution, from which it may
be precipitated in the metallic form, as already described. In place of
using, as above described, a chloride of iron resulting from the action
of muriatic acid on the ore itself, chloride of iron from other sources
may be employed, but the chloride from the ore will usually be the most
economical, and I believe that the other chlorides which it contains
render its action more efficacious than the action of the pure chloride
would be. Although I prefer to dissolve out from the roasted ore the
copper which it contains in a soluble state before the second calcination
with muriatic acid, or with chloride of iron, this is not essential as the
calcined ore may at once be roasted or recalcined with muriatic acid
or with chloride of iron, as above described, without any previous
separation of copper. I am aware that muriatic acid has been before
used for the purpose of extracting copper contained in ores in the state
of oxides or carbonates, or if from ores containing metallic sulphides
these have been directed to be operated on first by calcination with
common salt, then lixiviating in water with subsequent digestion in
muriatic acid; but my Invention avoids the use of common salt, utilizes
the waste muriatic acid produced in the manufacture of salt cake in the

page_text: place of the common salt, and in addition to the complete separation
of the copper by the more complete decomposition of the metallic
sulphides, it renders the residuary peroxide of iron more suitable for uso.
as an ore of iron.
What I claim is, the treatment of ores and minerals containing copper!
associated with sulphur by calcining or roasting, then re-calcining or
re-roasting the ore in the presence of muriatic acid or chloride of iron,,
and subsequently lixiviating the ore so as to dissolve out the copper as
chloride.
In witness whereof, I, the said Robert Oxland, have hereunto set 1
my hand and seal, this Thirteenth day of October, in the year
of our Lord One thousand eight hundred and sixty-eight.