IMPROVEMENTS IN DECOMPOSING THE SULPHIDES OF COPPER, SILVER, NICKEL, COBALT, LEAD, BARIUM, STRONTIUM, AND CALCIUM, AND IN OBTAINING COPPER, SULPHUR, AND OTHER PRODUCTS
Year: 1867

page_text: PROVISIONAL SPECIFICATION left by John Clark and Alexander Esilman
at the Office of the Commissioners of Patents, with their Petition, on
the 14th November 1867.
We, JOHN CLARK, Doctor of Philosophy, and ALEXANDER ESILMAN,
Chemist, both of Glasgow, in the County of Lanark, North Britain, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
DECOMPOSING THE SULPHIDES OF COPPER, SILVER, NICKEL, COBALT, LEAD, BARIUM,
STRONTIUM, AND CALCIUM, AND IN OBTAINING COPPER, SULPHUR, AND OTHER
PRODUCTS," to be as follows:-
This Invention has for its objects in a novel, improved, and economical
manner to decompose the sulphides of copper, silver, nickel, cobalt, lead,
barium, strontium, and calcium, and to obtain copper, sulphur, and other pro-
ducts, and it consists in treating the materials referred to with persalts of
iron, being based on the fact ascertained by the present applicants that the
persalts of iron have the property of decomposing the sulphides of the herein-
before mentioned metals, separating sulphur, and forming a salt of the metal
of the material operated upon.
The proposed mode of decomposing sulphides of copper is suitable for
treating the sulphur ores of copper, or the regulus, or the burnt ore, in order
to obtain the copper, and also leads to the utilisation of the sulphur of the two
first. The material reduced to a finely pulverised state is treated with a
solution of the persulphate or perchloride of iron. The desired reaction will
take place in the cold, but it is preferred to boil the mixture, by doing which it
is considerably hastered. The results of the reaction are the reduction of the

page_text: persalt to a protosalt of iron, the formation of the salt of copper corresponding
to the persalt used, and the liberation of the sulphur. At the same time the
greater part of the sulphur of the sulphide of iron present in the sulphur ores
of copper is separated, bisulphide of iron alone remaining undecomposed.
When the reaction is completed the cupreous solution is run off, and the
copper may be precipitated from it by means of metallic iron in the usual
way. The insoluble residue consists chiefly of sulphur, bisulphide of iron,
and earthy matters (when the regulus has not been used), and after being
dried may be used at once in the manufacture of sulphuric acid, or other
products ordinarily obtained from crude sulphur. The reduced salt of iron
may be reconverted into a persalt by well known means, so as to serve.for
treating fresh materials.
When the sulphur ore or regulus of copper contains any gold or silver,
these metals will be found with the separated sulphur and other matters that
are insoluble in the solution of the persalt of iron. If nickel or cobalt has
been contained in the materials it will be found in solution along with the salt
of copper, and may be obtained therefrom by any known means. It will
generally be convenient and economical to separate these metals only after
they have accumulated from the use of the solution with several successive
quantities of materials; the oxidation of the solution between each use not
interfering with this.
Sulphides of silver, nickel, and cobalt, or ores containing them, may be
treated for the separation of these metals and sulphur in the manner herein-
before described relating to copper.
Sulphide of lead or galena is to be treated with the perchloride of iron in
the same manner as is herein-before described relatively to copper, it being
preferred to boil the solution with the materials. The resulting chloride of
lead may be obtained by crystallisation from the solution, to be afterwards
treated according to any known manufacturing process. Any silver in the
lead ore remains in the form of insoluble chloride of silver.
Sulphide of barium being insoluble in water it is more convenient instead of
acting on the solid sulhide obtained by treating barytes or sulphate of baryta
with carbonaceous matter to mix a solution of the perchloride of iron with a
solution of the sulphide of barium. The reaction takes place immediately,
even in the cold. The resulting chloride of barium may be obtained by
crystallisation, or it may be converted into sulphate of baryta in the ordinary
way. The sulphur separated in this reaction is sufficiently pure for com-
mercial purposes.
The sulphide of strontium is to be treated like the sulphide of barium.

page_text: When the solid sulphide of calcium can be obtained in a state of sufficient
purity it may be at once treated with a solution of the perchloride of iron in
the cold or at a boiling temperature, when all the sulphur will be separated,
the chloride of calcium formed remaining in solution. When, however, the
sulphide of calcium is obtained in a state of mixture with other matters, as in
soda waste, it is necessary first to convert the solid into the soluble sulphides
of calcium in the ordinary way, and then either to precipitate the sulphur
from the solution by directly adding the perchloride of iron, or to add to the
solution a solution of protochloride of iron, or of protochloride of manganese,
or of both, so as to obtain sulphides of iron and of manganese, which are to
be treated with the perchloride of iron. The sulphur is then liberated, whilst
the protochlorides of iron and of manganese remain in solution, and will serve
for treating a fresh quantity of sulphides of calcium, the requisite portion of
the protochloride of iron being, of course, first reconverted into perchloride.