CERTAIN, IMPROVEMENTS IN TREATING CERTAIN METALLIC ORES, AND REFINING THE PRODUCTS THEREFROM
Year: 1845

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK,
BANKART, of Champion Park, Denmark Hill, in the County of Surrey, Gentle-
man, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Seventh day of August, in the ninth year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said Frederick
Bankart, Her especial licence, that I, the said Frederick Bankart, my execu-
tors, administrators, and assigns, or such others as I, the said Frederick
Bankart, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times during the term of
years therein expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, in the
Islands of Guernsey, Jersey, Alderney, Sark, and Man, and also within all
Her Majesty's Colonies and Plantations abroad, my Invention of "CERTAIN,
IMPROVEMENTS IN TREATING CERTAIN METALLIC ORES, AND REFINING THE PRODUCTS
THEREFROM;" in which said Letters Patent is contained a proviso, obliging me,
the said Frederick Bankart, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of my said Invention, and
in what manner the same is to be performed, and to cause the same to be
enrolled in Her said Majesty's High Court of Chancery within six calendar.
months next and immediately after the date of the said in part recited

page_text: Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Frederick Bankart, do hereby declare the nature of my said Invention as
follows, that is to say:-
My Invention relates to and includes all metallic ores containing copper,
whether in combination with sulphur or not in combination with it, and has for
its object to convert the copper into a soluble sulphate of its oxide, and sepa-
rating it from the foreign admixtures which the ores contain, to obtain it in
the refined inetallic state, and consists in adjusting and mixing together the
different ores before mentioned in such manner that those ores which hold
sulphur in excess may compensate those which are wholly or partially deficient in
sulphur, and in submitting the ores so adjusted and mixed to successive
roastings and lixiviations whereby a solution of sulphate of copper is obtained,
from which the copper may be precipitated in a refined metallic state.
And in order that my Invention and the means of carrying it into effect may
be fully understood, and before proceeding to the description herein-after
contained, I would premise that copper ores, as commonly known, are either
sulphurets, oxides, or carbonates, or a mixture of all or some of the above in
various proportions; they are also frequently mixed with bisulphuret of iron or
iron pyrites, and sometimes with the sulphurets of. zinc and lead, and other
foreign ingredients. The oxides and carbonates contain respectively oxygen
and carbonic acid, but no sulphur, bisulphuret of iron, or iron pyrites contains
iron and sulphur, and is frequently associated with and forms great part of the
sulphur ores of copper, and in the processes herein-after described furnishes
the sulphur in which the copper sulphurets as well as the oxides and carbonates
of copper are deficient for the conversion of their copper into sulphate, and
to allow for waste and for the sake of convenience I call the sulphur contained
in the bisulphuret of iron or iron pyrites, whether naturally combined in the
ores of copper or artificially mixed therewith in similar proportions, "sulphur
in excess," as existing in a greater proportion than is required to convert the
copper contained in the ore into a soluble sulphate of copper. It is well
known that no copper ores, except the copper pyrites or double sulphuret of
copper and iron, contain alone sufficient sulphur for the conversion of their
copper (when oxydized) into sulphate, whilst the oxides and carbonates do not
contain any sulphur, and, practically, much of the sulphur which copper ores
actually contain escapes in the form of vapour of sulphur, or sulphurous acid
gas and sulphuric acid, and which requires to be replaced from other sources.
The sulphur thus deficient is to be supplied by the bisulphuret of iron or

page_text: iron pyrites, either naturally associated with the ores of copper, as copper
pyrites, or by artificial mixture, previous to putting them into the furnace.
I now proceed to describe the method I use for carrying my Invention
into effect. I take copper ore as usually sampled and sold, and if not already
reduced to powder I pulverize it, and although this is not absolutely
essential, yet upon the greater or less completeness of this operation depends
very much the amount of fuel, labour, and time expended in the various. pro-
cesses berein-after described. The character of the ore with respect to the
relative proportions of copper and sulphur having been ascertained by analysis,
if the sulphur bears a less proportion to the copper than one to two, I add
iron pyrites or copper pyrites, also pulverized in such quantities as will raise
the proportion of the sulphur to the copper in the mixture to at least that
above stated, namely, one to two. If two or more descriptions of copper
ores are to be treated as sulphurets, oxides, carbonates, or other natural com-
binations of copper, they are to be mixed together in such proportions as will
make the sulphur of the mixture bear to the copper of the mixture at least
the proportion of one to two, adding iron or copper pyrites, as before stated,
where necessary to ensure at least that proportion of sulphur to copper. And
I would observe, that care must always be taken to have a sufficient quantify
of sulphur ores for the conversion of the copper into a soluble sulphate of its
oxide, and also to allow for the escape of part of the sulphur during the pro-
cesses, either as vapour of sulphur, or sulphurous acid, or sulphuric acid. The
copper ore, prepared and adjusted in the manner before mentioned, is then to
be submitted to such a degree of heat in free attact with atmospheric air as
will oxidize the metals not already in a state of oxide, and convert the sulpbur
into sulphuric acid. For this purpose I place the ore or mixture of ores in a
common reveberatory furnace, and I submit the ore to a dull red heat in free
contact with the atmospheric air until the mixture attains a state of seeming
fluidity, which I find to be most favorable for the decomposition of the ores
and for the conversion of the copper into a sulphate, and I retain the mix-
ture in that state until the evolution of sulphurous vapour nearly ceases, and
instead of laying the mixture on the sole floor or hearth of the furnace at on 'e
in a bed of from three to four inches in thickness, I prefer, in order to the
more speedy accomplishment of the object in view, to divide the mixture into
several portions, and having put one portion into the furnace I add another
portion when the first has attained a dull red heat and the metals are becoming
partially oxidized, and I keep repeating these additions under similar circum-
stances until the whole of the ore is put into the furnace; and I find that by
this mode the furnace is neither elegged nor injuriously cooled, and the ore is

page_text: more rapidly decomposed than when all is put into the furnace at once, whilst
the sulphur of the latter portions of ore, from their coming into immediate
contact with the partially oxydized metals, is more rapidly and with less waste
converted into sulphuric acid, which, finding oxide of copper ready formed in
the first portions of ore, unites with it, and forms sulphate of copper. The
mixture is frequently stirred so as to expose fresh surfaces to the atmospheric
air for the absorption of oxygen.
In this first roasting a part only of the copper is converted into a sulphate,
.and the remainder, which was not already so, into an oxide; but by repeating
the process of roasting, the residual mixture, in conjunction with fresh sulphur
ore, in the proportions before mentioned for the first roasting, and also
.herein-after described, and which may be either before or after lixiviation
next described, this remaining oxide of copper will be converted into a
sulphate; but I prefer to wash the ore after each roasting, in order that a
part of the copper may be in a course of precipitation whilst the remainder is
undergoing decomposition in the furnace, as by this means a saving of time is
effected. The evolution of sulphurous vapour having ceased, or nearly so, I
remove the mixture from the furnance to an adjoining vat or pit, and apply to
it water (or a weak sulphate liquor from a previous lixiviation) of about the
boiling temperature, and I retain it at that temperature some little time by
means of injected steam, the better to ensure the solution of the sulphate of
copper, and having drawn off the sulphate of copper liquor from the residuum
mixture, which I call "insoluble residue," I set the latter aside in readiness
for subsequent use, previously drying it or not, as may be convenient; I next
assay this insoluble residue and determine by analysis the quantity of copper
and of sulphur (if any remain unacidified), and I then add iron pyrites or copper
pyrites in such quantity as will make the quantity of sulphur contained in the
mixture at least equal to half the quantity of copper therein; I then return this
mixture so adjusted into the furnace and subject it to a second process of roast-
ing, conducted in a similar manner to the one already described, and continued
as before until the sulphurous vapour has ceased to be evolved, or nearly so,
and the mixture is then subjected to a second lixiviation conducted as before
described. I repeat this process of adjusting the mixture, roasting, and lixivia-
tion as herein-before described with the successive residuums once, twice, or
oftener, according to the character of the ores under operation, some yielding
the whole of their copper to two operations, whilst others may require three or
more before the copper is entirely separated; and in the second and subsequent
furnace treatments, if the fresh sulphur ore to be used be copper pyrites and
is not already in powder, I prefer to use it in small lumps, by which means I

page_text: obtain the sulphur more gradually, and make it available with less waste fór
the formation of sulphate of copper with the smallest residuum, and these
lumps being afterwards separated by means of a sieve and pulverized, are used
to charge the furnace àfresh, and when the copper ore is all in powder, iron
pyrites should be used for the last roasting, so as to avoid a remainder of
copper.
The next process is to precipitate the copper from its sulphate solution,
after which it is to be fused and run into moulds, when it is ready for use or
sale as fine metallic copper.
Various known modes of precipitation may be
adapted, but I precipitate by means of iron, either cast or wrought metal,
which I prefer to be in plates, as presenting a larger surface to the action of the
liquid, always keeping the solution at a temperature of from about 120° to 150°
of Fahrenheit's scale, and as nearly as may be of the same strength, by means
of a circulating stream of fresh sulphate solution, which, entering towards the
top and conducted through a pipe downwards, tends to displace by its greater
specific gravity the lighter liquid or sulphate of iron which overflowing is to
be returned into the lixiviating vat to be recharged with sulphate of copper,
and this again precipitated until the refuse liquid becomes a nearly saturated
solution of sulphate of iron, when it is set aside to crystalize. The two con-
ditions of high temperature in the sulphate solution, and the maintenance of a
fresh circulating stream in the vat, contribute to the rapidity of precipitation,
and to preventing the free acid of the sulphate solution from attacking
and dissolving the iron beyond its corresponding. A proportionate weight of
copper precipitated. The sulphurous acid vapours proceeding from the various
roasting processes herein-before described may, if desired, be condensed either as
sulphurous acid, or employed for the manufacture of sulphuric acid, according
to various well-known methods.
Having described the nature of my Invention, and the method of carrying
it into effect, I would remark that variations may be made in some of the
arrangements and details without departing from my Invention, so long as
the general principle of it is retained; and I would also remark, that although
my Invention depends on the decomposition of the sulphuret of copper, and
the formation of a soluble sulphate of the oxide of copper, I do not claim
to be the discoverer of such decomposition, or of the formation of such
soluble sulphate; I do not, therefore, claim as my Invention the principle
of decomposing sulphuret of copper ores and forming a sulphate of copper,
which has been long known; nor do I claim the obtaining a soluble sulphate
of copper from copper ores; neither do I claim as my Invention the pre-
cipitation of metallic copper from a sulphate solution; nor do I claim the

page_text: furnace herein-before referred to, except so far as the same may be used for
the purposes of my Invention. But what I claim is, the mixing of the different
ores of copper and iron pyrites in due proportion, according to the quantity of
sulphur relatively with the copper which they respectively contain, and adjust-
ing them in such manner as that those ores which hold sulphur in excess may
compensate others which are only or partially deficient in sulphur, and in
subjecting such mixture to a succession of roastings and lixiviations, (the
residuum after each roasting having the proportion of copper to sulphur
adjusted as before,) and thereby obtaining a solution of sulphate of copper,
whence the copper is obtained by precipitation in a refined state.
Inrolled the Seventh day of February, One thousand eight hundred and
forty-six.