IMPROVEMENTS IN THE PURIFICATION OF PRECIPITATED COPPER."
Year: 1881

page_text: LETTERS PATENT to Frederic Claudet, of Coleman Street, in the City of
London, for an Invention of "IMPROVEMENTS IN THE PURIFICATION OF
PRECIPITATED COPPER."
PROVISIONAL SPECIFICATION left by the said Frederic Claudet at the
Office of the Commissioners of Patents on the 2nd December 1881.
FREDERIC CLAUDET, of Coleman Street, in the City of London.
IN THE PURIFICATION OF PRECIPITATED COPPER."
"IMPROVEMENTS
In the various processes for the extinction of copper from its ores or other
products by humid methods, the copper is usually thrown down by immersing scrap
iron, sponge iron, or cast iron, in the cupreous solutions.
The precipitated copper thus obtained is in almost all cases contaminated by the
presence of varying quantities of arsenical compounds; in the subsequent smelting
of such precipitates the removal of arsenic is accomplished with difficulty, and an
inferior quality of ingot copper results.
This Invention has for its object the removal of the arsenic in the arsenical
compounds mixed with the precipitated copper previously to smelting, and the
consequent more ready production of ingot copper free from arsenic.
For this purpose I treat the precipitated copper, either in the wet state as
obtained from the precipitating vats, or in a partially or completely dried state
with a solution of caustic or carbonated alkali, or a mixture of both. I prefer for
the purpose a solution of caustic soda or carbonate of soda, or a mixture of both,
although the corresponding potassium compounds may also be employed.
By this treatment the arsenical compounds are converted into soluble arsenical
salts of soda or potash, which are removed from the precipitate by the alkaline
solution, and by subsequent washing with hot or cold water.
The precipitate so purified is smelted in the usual way..

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederic Claudet in the Great Seal Patent Office on the 26th May
1882.
FREDERIC CLAUDET, of Coleman Street, in the City of London.
IN THE PURIFICATION OF PRECIPITATED COPPER."
"IMPROVEMENTS
In the various processes for the extraction of copper by what is known as the
humid method, the copper is usually precipitated by immersing in the cupreous
solution scrap iron, sponge iron, or cast iron. The precipitated copper thus thrown
down is in almost all cases contaminated by the presence of. varying quantities of
arsenical compounds. In the subsequent smelting of such precipitated copper the
removal of the arsenical compounds is accomplished with difficulty, and an inferior
quality of copper consequently results.
Now this Invention has for its object the removal of the arsenical compounds
from the precipitated copper previously to smelting the same, and the consequent
more ready production of ingot or cake copper free from arsenic.
For this purpose I either treat the precipitated copper when in the wet state or
condition as obtained from the precipitating vats, or when it exists in a partially or
completely dried state or condition, with a solution of caustic or carbonated alkali,
or with mixtures of the same.
I prefer for this purpose to employ a solution of caustic soda, or a solution of
carbonate of soda, or a mixture of the same, which solutions may be employed
either at the ordinary or at an elevated temperature.
It will however be understood that the corresponding alkaline potassium
compounds or mixtures of the same may also be employed. By this means the
arsenical compounds existing in the precipitated copper are converted into soluble
arsenical salts, either of soda or potash, which are removed from the precipitated
copper by the alkaline solution, and by subsequent washing, either with hot or with
cold water.
In some cases it is preferable to moisten the precipitated copper to be purified
with a strong solution of a caustic alkali, or of an alkaline carbonato, or of a
mixture of the two, as herein before mentioned, and after drying the mass to
subject it to a suitable heat in a muffle or other furnace.
The arsenical compounds thus formed are subsequently removed in the form of
soluble arsenical salts, either of soda or of potash, by lixiviating the heated
mixture with water, by preference with water at an elevated temperature.
The proportions in which the caustic or carbonated alkalies are to be employed
will be dependent upon the amount of the arsenical compounds existing in the
precipitated copper, but I have found that in treating ordinary English precipitate
made from Spanish or Portuguese pyrites, three to about five per cent of alkali or
its equivalent give good results.
But other proportions may be adopted, my object being to convert the arsenical
compounds existing in the precipitated copper into easily soluble salts, in order
that they may be removed, and that the copper may be obtained in a purer
condition.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein before in part
recited Letters Patent is,-
First. Effecting the separation of arsenical compounds from precipitated copper E
by submitting the same to the action of a solution of a caustic alkali, or of an

page_text: alkaline carbonate, substantially in the manner as hereinbefore described, in order
that the copper smelted therefrom may be obtained free from arsenic.
Second. Effecting the separation of arsenical compounds from precipitated
copper by the employment of a caustic alkali, or of an alkaline carbonate, in
conjunction with heat, substantially in the manner as herein before described, in
order that the copper smelted therefrom may be obtained free from arsenic.
In witness whereof, I, the said Frederic Claudet, have to this my Specification
set my hand and seal, this Twenty third day of May, One thousand eight
hundred and eighty two.
FRED. CLAUDET. (L.S.)