A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
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130 THE METALLURGY OF ANTIMONY.<br />
evolved in the above reaction, in order to produce fresh quantities of<br />
the sulph-liydrate solution.<br />
Izart describes a process for the extraction of antimony by dissolving<br />
antimony ores with sodium sulphide. The solution is electrolysed in a<br />
vat divided, by a diaphragm, into a cathode compartment, into which<br />
the solution is put, and an anode compartment, which is filled with a 17<br />
per cent, caustic soda solution. Sufficient ammonium chloride is added<br />
to the soda solution as will raise its. specific gravity to that of the<br />
antimony solution. At Cassagnes, France, the process yielded a<br />
lustrous scaly deposit of metallic antimony: the current density was<br />
0*8 ampere per square decimetre; the E.M.F., 1*6 volts; the yield,<br />
76 per cent.; the output per kilowatt, 0*55 kg. antimony, which was<br />
finally raised to 0*621 kg.<br />
At Lixa, near Oporto, Portugal, the following process, for the<br />
extraction of both antimony and gold from impure antimony, had<br />
been tried, and was finally given up on account of high working<br />
cost:—Plates of the impure antimony were used as anodes, while the<br />
electrolyte was a solution of antimony trichloride, made by dissolving<br />
the trichloride in a concentrated solution of salt, potassium chloride,<br />
or ammonium chloride strongly acidified with hydrochloric acid.<br />
When current was passed, the antimony dissolved out from the anode<br />
was deposited on the cathode; while the gold, in the form of fine<br />
powder, fell to the bottom of the cell.<br />
In Sanderson's pi-ocess, a solution of butter of antimony, in a very<br />
concentrated solution of sodium, potassium, or ammonium, acidified<br />
with hydrochloric acid, is used as an electrolyte, in which are suspended<br />
antimony anode plates containing gold. When a current is<br />
passed, the antimony is deposited on the cathode and the gold<br />
particles fall to the bottom of the vat. This process is too costly;<br />
moreover, a chloride solution can never afford a good deposit.<br />
Betts, at a meeting of the American Electro-chemical Society,<br />
September 18, 1905, stated that an acid ferric chloride solution attacks<br />
stibnite with ease, producing a solution of ferrous and antimonious<br />
chlorides and a residue of sulphur; from this solution metallic antimony<br />
and ferrous chloride can be recovered electrolytically.<br />
IY. REFINING OF ANTIMONY.<br />
Unrefined antimony, as already stated, usually contains sulphur,<br />
iron, arsenic and copper, and frequently lead. These impurities,<br />
with the exception of lead, can be eliminated partly by oxidising and<br />
slagging agents, partly by sulphurising agents, and partly by<br />
chlorinating agents. Soda or potash or antimony glass (antimony oxy-