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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THE METALLUKGY OF ANTIMONY. 125<br />
metal arid alkaline-earfch metal sulphides. The resulting reaction is<br />
the production of a solution of soluble thio-antimonates, Na3SbS4<br />
or Ca3(SbS4)2J and thio-antiinonites, Na3SbS3 or Ca3(SbS3)2. These<br />
solutions can be electrolysed with the greatest ease.<br />
The results of the experiments made by Borchers in 1886 prove<br />
that antimony was deposited in equal quantity both from the thioantimoniate<br />
and thio-antimonite. If a sodium thio-antimonate<br />
solution be used, it is only necessary to add either sodium sulphide<br />
or sodium hydroxide, in such quantity that there is at least one<br />
atom of sodium for every atom of sulphur, in order to prevent the<br />
separation of sulphur at the anode. In other words, the action takes<br />
place best when three molecules of sodium sulphide (Na2S) are present<br />
for each molecule of antimony sulphide (Sb2S8).<br />
The relative distribution of the elements before and after the<br />
experiment is shown in the following table :—<br />
Before electrolysis—<br />
In form of salts, etc.<br />
After electrolysis—<br />
In metallic form .<br />
In solution—<br />
2'410 kgrm. NaSH .<br />
1-202 ,, NaA .<br />
1*491 ,, Na^Oa + SHoO<br />
Antimony.<br />
Kgvms.<br />
2*440<br />
2-437<br />
2-437<br />
Sodium.<br />
Kgvms.<br />
1-840<br />
0*990<br />
0*503<br />
0-275<br />
1-768<br />
Sulphur.<br />
K grins.<br />
2-560<br />
1-377<br />
0-699<br />
0-384<br />
2*460<br />
Oxygen.<br />
Kgrm.<br />
0*020<br />
...<br />
0-288<br />
0-288<br />
The loss of antimony (3 grms.) is so small that the precipitation<br />
may be considered as practically quantitative. The loss of sodium<br />
and sulphur is due to the fact that the solution clinging to the<br />
antimony after the powder had been removed was not added to the<br />
rest of the liquid.<br />
The experiments, as carried out by Borchers, also show a peculiar<br />
fact, that with the same expenditure of current the same quantity of<br />
antimony is deposited, whether it exists in the solution as the<br />
trivalent or as the pentavalent antimony.<br />
Practical Working of the Electrolytic Process.—The sodium sulphide<br />
solution in the conical iron vessels (figs. 55-58, a) is treated and<br />
agitated by means of steam introduced through the steam-pipe b. As<br />
soon as the solution is boiling, the finely divided ore is sprinkled into