IMPROVEMENTS IN TREATING CUPREOUS SOLUTIONS OBTAINED BY HENDERSON'S HUMID PROCESS OR OTHERWISE, IN ORDER TO PURIFY THE PROVISIONAL SPECIFICATION
Year: 1875

page_text: LETTERS PATENT to Henry Chadwick and William Jardine, of
Irvine, in the County of Ayr, North Britain, Chemists, for the
Invention of "IMPROVEMENTS IN TREATING CUPREOUS SOLUTIONS OBTAINED
BY HENDERSON'S HUMID PROCESS OR OTHERWISE, IN ORDER TO PURIFY THE
PROVISIONAL SPECIFICATION left by the said Henry Chadwick and
William Jardine at the Office of the Commissioners of Patents,
with their Petition, on the 23rd August 1875.
We, HENRY CHADWICK and WILLIAM JARDINE, of Irvine, in the
County of Ayr, North Britain, Chemists, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN TREATING CUPREOUS SOLUTIONS
OBTAINED BY HENDERSON'S HUMID PROCESS OR OTHERWISE, IN ORDER TO PURIFY
THE COPPER AND UTILISE SEPARATED SUBSTANCES," to be as follows, that is to
say:

page_text: for obtaining copper from ores; but it is also applicable to cupreous
solutions, howsoever obtained, when containing other metallic salts
besides those of copper, and when it is desirable to separate and utilise
such other metallic salts. Cupreous solutions of the kind referred to
vary very much in composition, and whilst the application of the present
Invention will in most cases conduce to the obtainment of a purer
copper more profit will be derived from it in those cases in which the
solutions contain salts of silver.
The Invention consists in adding to the cupreous solution acetate or
other suitable salt of lead in proportion corresponding to the silver salt i
present. When there is some lead salt in solution then only what is
required to make it up to the proper proportion needs to be added, and
when the cupreous solution also contains salts or compounds of arsenic,
antimony, or bismuth, then a further quantity of the lead salt corre-
sponding to them must be added.
As an example of the practical application of the Invention the
following details may be given, these details being however variable in
different cases,-
-
First. To the usual strong cupreous solution of the Henderson process
of from 40 to 60 degrees Twaddell after being decanted from sediment
there are added 8 to 10 grains of acetate of lead per gallon of the liquor.
The weaker acid liquors of the Henderson process and containing
sulphuric acid and sulphates are then added. The mixture which
should be of about 20 degrees Twaddell is well agitated.
Secondly. If the strong solution contains without much diminution
the lead salts commonly in the ores, a less addition than 8 grains per
gallon of acetate of lead may be sufficient; but it is generally safer to
add the full proportion stated, or even more, and whilst it can do no
harm there is no objection on the score of its cost. Besides precipitating
the silver salts the lead takes down arsenic acid, antimonic acid,
and any traces of bismuth, and thereby increases the purity of the
copper.
Thirdly. On the addition of the lead salt and dilution, if necessary, to
about 20 degrees Twaddell, the contents of the tank or vat should be
well agitated, and then allowed to settle for about 12 hours, or until
the temperature falls to about 60 degrees Fahrenheit, and the super-

page_text: natant solution is clear. The clear liquor is next run off to the copper
precipitating tanks.
Fourthly. The slimy precipitate remaining is allowed to accumulate
from successive charges of liquor, and each charge has the 8 to 10 grain.
lead salt added. When the precipitate becomes voluminous or incon-
venient fresh dilated solutions are added without any lead salt until the
liquors on being tested begin to show silver, when more lead salt is
carefully added as long as any silver remains in solution. It has been
found that in ordinary liquors cach part of (metallic) silver requires
about two parts of acetate of lead.
Fifthly. The precipitate transferred to a smaller vessel is washed with
hot dilute sulphuric acid to dissolve any remaining copper, which is
finally removed by repeated washings. The precipitate or mud is then
transferred to a smaller vessel, and is treated with granulated zinc or
spongey iron and dilute acid, preferably sulphuric, and after careful
washing with water to free it from soluble chlorides is smelted and
refined in the ordinary manner.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Chadwick and William Jardine in the Great
Seal Patent Office on the 22nd February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, HENRY
CHADWICK and WILLIAM JARDINE, of Irvine, in the County of Ayr,
North Britain, Chemists, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of August, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto us, the said Henry Chadwick and William
Jardine, Her special licence that we, the said Henry Chadwick and
William Jardine, our executors, administrators, and assigns, or such
others as we, the said Henry Chadwick and William Jardine, our
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during

page_text: the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IM-
PROVEMENTS IN TREATING CUPREOUS SOLUTIONS OBTAINED BY HENDERSON'S HUMID
PROCESS OR OTHERWISE, IN ORDER TO PURIFY THE COPPER AND UTILISE SEPARATED
SUBSTANCES," upon the condition (amongst others) that we, the said Henry
Chadwick and William Jardine, our executors or administrators, by an
instrument in. writing under our, 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 we, the said Henry Chadwick and William
Jardine, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement in writing, that is
to say :-
"
Our said Invention relates to the treatment of cupreous solutions
obtained by what is now well known as "Henderson's humid process
employed for obtaining copper from ores; but it is also applicable to
cupreous solutions, howsoever obtained, when containing other metallic
salts besides those of copper, and when it is desirable to separate and
utilise such other metallic salts. Cuprcous solutions of the kind referred
to vary very much in composition, and whilst the application of our
present Invention will in most cases conduce to the obtainment of a
purer copper, more profit will be derived from it in those cases in which
the solutions contain salts of silver.
.
Our said Invention consists essentially in adding to the cupreous
solutions acetate or other suitable salt of lead in proportion corre-
sponding to the silver present. When the cupreous solution also
contains salts or compounds of arsenic, antimony, or bismuth, then a
further quantity of the lead salt corresponding to them must be added.
And in order that our said Invention and the manner of performing
the same may be properly understood, we will now by way of example
particularly describe the details of our process as applied in certain
cases, premising that these details are variable in different cases..

page_text: To the usual strong cupreous solution, of the Henderson process of
from 40 to 40 degrees Twaddell, sufficient water is added to reduce the
strength to about 20 degrees. The water is, by preference, first put into,
the tank in which the treatment is to be effected, and brisk agitation is
maintained, whilst the cupreous solution is being poured into the water.
A weak solution of the actate of lead containing about 8 or 10 grains
for every gallon of the original strong solution is then poured in, the
agitation being still maintained. We have found that in ordinary strong
liquors each part of (metallic) silver requires about two parts of acetate
of lead. The weaker acid liquors of the Henderson process containing
sulphuric acid and sulphates, together with arsenic, antimony, and
bismuth, are treated separately, but in a precisely similar manner with
the main object however of purifying the copper.
If the strong solution contains without much diminution the lead
salts commonly in the ores, a less addition than 8 grains per gallon of
the acetate of lead may in some cases be sufficient; but we generally
find it safer to add the full proportion stated, or even more, and whilst it.
can do no harm there is no objection on the score of its cost. Besides
precipitating the silver the sulphate of lead which is formed takes
down arsenic acid, antimonic acid, and any traces of bismuth, and by
doing so increases the purity of the copper.
During the addition of the acetate of lead and the dilution to about
20 degrees Twaddell, the liquors should be well agitated and be after-
wards allowed to settle for about 12 hours or until the temperature falls
to about 60 degrees Fahrenheit, and the supernatant solution is clear.
The clear liquor is next run off to the copper precipating tanks.
The slimy precipitate remaining may either be allowed to accumulate
from successive charges of liquor; or the precipitate from each charge
may be at once transferred to a smaller tank in which it may be allowed
to accumulate.
The precipitate is finally washed with hot and very dilute sulphuric
acid to dissolve any remaining copper which is finally removed by
repeated washings. At this stage we contemplated treating the
precipitate with granulated zinc or spongey iron and acid; but we find
such treatment to be unnecessary, and the precipitate may be at once
smelted and refined in the usual manner.

page_text: Almost any salt of lead (excepting the sulphate which is formed in
the process) may be used, but we prefer the acetate from considerations
of economy and convenience.
Having thus particularly described our said Invention and the manner
of performing the same, we have to state that what we believe to be
novel and original, and claim as the Invention secured to us by the
herein-before in part recited Letters Patent is,―
1. The purifying of cupreous solutions containing salts of other metals
besides copper by treating them with acetate or other suitable salt of
lead, as herein-before described.
2. The separating and utilising of silver contained in cupreous
solutions by treating them with acetate or other suitable salt of lead, as
herein-before described.
3. The separating of arsenic, antimony, and bismuth, or any of them
from cupreous solutions by treating them with acetate or other suitable
salt of lead, as herein-before described.
In witness whereof, I, the said William Jardine, on behalf of
the said Henry Chadwick and myself, have hereunto set my
hand and seal, this Nineteenth day of February, in the year of
our Lord One thousand eight hundred and seventy-six.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
W. JARDINE. (L.S.)