A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...

130 THE METALLURGY OF ANTIMONY.
evolved in the above reaction, in order to produce fresh quantities of
the sulph-liydrate solution.
Izart describes a process for the extraction of antimony by dissolving
antimony ores with sodium sulphide. The solution is electrolysed in a
vat divided, by a diaphragm, into a cathode compartment, into which
the solution is put, and an anode compartment, which is filled with a 17
per cent, caustic soda solution. Sufficient ammonium chloride is added
to the soda solution as will raise its. specific gravity to that of the
antimony solution. At Cassagnes, France, the process yielded a
lustrous scaly deposit of metallic antimony: the current density was
0*8 ampere per square decimetre; the E.M.F., 1*6 volts; the yield,
76 per cent.; the output per kilowatt, 0*55 kg. antimony, which was
finally raised to 0*621 kg.
At Lixa, near Oporto, Portugal, the following process, for the
extraction of both antimony and gold from impure antimony, had
been tried, and was finally given up on account of high working
cost:—Plates of the impure antimony were used as anodes, while the
electrolyte was a solution of antimony trichloride, made by dissolving
the trichloride in a concentrated solution of salt, potassium chloride,
or ammonium chloride strongly acidified with hydrochloric acid.
When current was passed, the antimony dissolved out from the anode
was deposited on the cathode; while the gold, in the form of fine
powder, fell to the bottom of the cell.
In Sanderson's pi-ocess, a solution of butter of antimony, in a very
concentrated solution of sodium, potassium, or ammonium, acidified
with hydrochloric acid, is used as an electrolyte, in which are suspended
antimony anode plates containing gold. When a current is
passed, the antimony is deposited on the cathode and the gold
particles fall to the bottom of the vat. This process is too costly;
moreover, a chloride solution can never afford a good deposit.
Betts, at a meeting of the American Electro-chemical Society,
September 18, 1905, stated that an acid ferric chloride solution attacks
stibnite with ease, producing a solution of ferrous and antimonious
chlorides and a residue of sulphur; from this solution metallic antimony
and ferrous chloride can be recovered electrolytically.
IY. REFINING OF ANTIMONY.
Unrefined antimony, as already stated, usually contains sulphur,
iron, arsenic and copper, and frequently lead. These impurities,
with the exception of lead, can be eliminated partly by oxidising and
slagging agents, partly by sulphurising agents, and partly by
chlorinating agents. Soda or potash or antimony glass (antimony oxy-