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 ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
THE METALLURGY OF ANTIMONY. 107<br />
The operation is thus :—<br />
Roasted ore charged at a time . . .5 cwts.<br />
Cover of Glauber salt 1 cwt.<br />
Coarse, hard wood-charcoal, powdered . 82 lbs.<br />
Before the first charge is made the bed of the furnace must be heated<br />
to redness. The charge generally melts in about four hours, when it<br />
begins to effervesce, with the evolution of carbonic oxide, which escapes<br />
through the layer of slag and burns. The charge is rabbled until<br />
boiling ceases, when it is allowed to settle for half an hour. After<br />
this the charge is allowed to cool by leaving the fire-door open. This is<br />
continued until the slag attains a low red heat and, being in a pasty<br />
condition, is drawn off. Refining materials—27*5 lbs. of Glauber salt<br />
and 11 lbs. of wood-charcoal—are immediately added, and the furnace<br />
is strongly heated. After an hour and a half, when boiling ceases, the<br />
metal and the slag are drawn off together into an iron mould. Care<br />
must be taken to leave at least half an inch of slag as a cover for the<br />
metal, thus preventing the possibility of the metal solidifying before<br />
the mould is filled. As soon as the ingot becomes solidified, the slag—<br />
essentially a sulpho-salt of antimony mixed with sodium carbonate,<br />
containing about 15 per cent, of antimony—is removed and is again<br />
smelted with one-fifth of its weight of iron for subsequent use.<br />
At one of the works in Hungary the refining is said to be combined<br />
with the reduction. In a reverberatory furnace 5 cwts. of<br />
roasted ore are smelted with 10 per cent, of small coal, together with<br />
3 to 6 per cent, of Glauber salt, for twenty hours; after the removal of<br />
the slags thus formed, 22 to 25 lbs. of slag from a previous refining<br />
of antimony are added. The ladling of the metal is commenced as<br />
soon as this is fused.<br />
According to M. Herrenschmidt, the trioxide produced by the<br />
volatilisation method can be reduced in the following way:—An<br />
ordinary reverberatory furnace furnished with condensing apparatus,<br />
as shown in fig. 52, is previously heated before the following charge<br />
is commenced:—<br />
10 parts of the trioxide.<br />
6 parts of crude antimony.<br />
1 part of carbon (charcoal or anthracite).<br />
After six hours the charge must be thoroughly rabbled, with the<br />
result that antimony metal is formed.<br />
The following proportions may be employed:—<br />
80 parts of trioxide.<br />
20 parts of sulphide (crude).<br />
12 to 15 parts of carbon.