IMPROVEMENTS IN THE PURIFICATION OF COPPER PRECIPITATE AND ORES AND IN THE PRODUCTION OF COMMERCIAL PROVISIONAL SPECIFICATIONSPHOROUS COMPOUND
Year: 1882

page_text: LETTERS PATENT to David Watson of Manchester in the County of Lancaster
Metallurgist for an invention of "IMPROVEMENTS IN THE PURIFICATION OF
COPPER PRECIPITATE AND ORES AND IN THE PRODUCTION OF COMMERCIAL
PROVISIONAL SPECIFICATION left by the said David Watson at the Office
of the Commissioners of Patents on the 17th March 1882.
"6
DAVID WATSON of Manchester in the County of Lancaster Metallurgist.―
'IMPROVEMENTS IN THE PURIFICATION OF COPPER PRECIPITATE AND ORES AND IN
THE PRODUCTION OF COMMERCIAL ARSENIC AND PHOSPHOROUS COMPOUNDS."
This invention has for its object the purification of copper precipitate made by
the wet processes of copper extraction from certain impurities hereinafter specified
and also the purification of ores of copper containing arsenites, arseniates, phos-
phates, tin or its compounds or oxychlorides of copper, from the arsenic, phosphorous,
tin and chlorine respectively.
To effect this purification I submit the copper precipitate or ore to be treated to
the action of caustic alkalies, sulphides or carbonates separately or either or any of
them in conjunction by leaving it in contact with solutions of these alkaline
compounds and assisting the action by the application of heat if desirable.
The result of this is that arsenic, chlorine, phosphorous and tin that may be
present in the precipitate or ore are removed wholly or in part as alkaline
compounds.
The modus operandi must vary in its details according to the material to be
treated. In ordinary cases I prefer caustic soda as the alkaline compound to b
used,
The following method may be employed for dealing with copper precipitate of
ordinary quality. The precipitate is heated to a temperature approaching one

page_text: hundred degrees Centigrade for three hours or more or less in a vessel of iron or
other suitable material with twice its weight or more or less of a solution containing
by preference ten per cent of ordinary commercial caustic soda.
In this operation arsenic, phosphorous, tin and chlorine or any or all of them
pass into solution. The liquor is removed by the ordinary methods and the washed
precipitate treated with water to remove the alkaline liquor still remaining: this
wash water is then removed and the residual washed precipitate dried to prepare
it for the ordinary processes of copper smelting.
The removal of the above mentioned substances improves the quality of the
copper and diminishes the cost of the smelting of the precipitate and the solution
may be employed as a source of commercial arsenic and phosphorous compounds.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said David Watson in the Great Seal Patent Office on the 15th September
1882.
DAVID WATSON of Manchester in the County of Lancaster Metallurgist.
"IMPROVEMENTS IN THE PURIFICATION OF COPPER PRECIPITATE AND ORES AND IN
THE PRODUCTION OF COMMERCIAL ARSENIC AND PHOSPHOROUS COMPOUNDS."
This invention has for its object the purification of copper precipitate made by
the wet processes of copper extraction from certain impurities hereinafter specified
and also the purification of ores of copper containing arsenites, arsenates, or oxy-
chlorides of copper from the arsenic and chlorine respectively.
In the case of copper precipitate I submit the precipitate to be treated to the
action of a solution of sodium or potassium sulphide assisting the action usually by
the application of heat.
The varieties of precipitate produced commereially and to the purification of
which this process is directed differ as to the nature and amount of the substances
other than copper that they contain. The object with which I treat precipitate by
my process is to effect the removal of arsenic, phosphorus, chlorine and tin, any or
all of them.
Arsenic is almost always present, the presence of the others depends on the
process employed for preparing the solutions from which the copper precipitate was
prepared and the material used for the precipitation. The amount of alkaline
sulphide to be employed for purification depends, ceteris paribus, on the amount
of these impurities present. In dealing with copper precipitate such as that pro-
duced by the Rio Tinto Company I have found that by heating it for three hours
at a temperature approaching 100° C. with a solution of twenty per cent of its
weight of sodium sulphide (Na, S) more than seventy five per cent of the arsenic
and the larger proportion of the phosphorus is removed. The arsenic and phosphorus
pass into solution as sodium or potassium arsenate.
A further removal of arsenic is effected by a second treatment by sodium or
potassium sulphide.
From precipitate containing chlorides and metallic tin the whole of the chlorine
and tin are removed in this process.
I do not find it necessary to use a larger proportion than twenty per cent of
sodium sulphide for the purification of any of the varieties of copper precipitate
made except in exceptional cases.
The purified precipitate after having been washed and dried is then in a condition
for the ordinary processes of copper smelting.
In the case of ores I submit the ores containing arsenic or chlorine or both as
arsenate or arsenite of copper and oxy-chloride of copper to the action of solutions
of alkaline hydrates (caustic alkalies) carbonates or sulphides, any or all of them,
assisting the action by the application of heat. Previous to treatment I grind the
ore to powder. In this way I effect the complete decomposition of the above
minerals, the arsenic and chlorine passing into solution.
The amount of the alkaline compounds to be used for the purification of an ore
will depend, ceteris paribus, on the amount of the arsenical or chlorine compounds
present.
The alkaline solutions proceeding from the above processes contain alkaline.
arsenates, arsenites, phosphates, or chlorides any or all of them and those containing

page_text: the arsenic and phosphorous compounds are available for the preparation of
commercial arsenic and phosphorous compounds.
In conclusion I claim as my invention :-
1-The treatment of copper precipitate by solutions of alkaline sulphides in the
manner and with the object detailed above.
2. The treatment of the varieties of copper ores specified by solutions of alkaline
hydrates, carbonates or sulphides for the removal of arsenic and chlorine as herein
described.
In witness whereof I the said David Watson have hereunto set my hand and
seal this fourteenth day of September One thousand eight hundred and
eighty two.
DAVID WATSON. (L.S.)