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

112 THE METALLURGY OF ANTIMONY.
Balls, about the size of an egg, are made of tho following
composition :—
The trioxide 82 per cent.
Carbon (anthracite or powdered charcoal) . .12 ,,
Carbonate of soda 6 to 7 ,,
These balls are charged into the furnace with 5 to 20 per cent,
coke. The loss of oxide is about 33 per cent., which can be recovered
from the condensing chambers, as shown in fig. 45.
The metal thus obtained has to be remelted, either in a crucible
or in a reverberatory furnace, for the purpose of " starring."
(c) Reduction in Crucibles.—This method, on account of its high
cost, is only adopted when the ores are rich or when crude antimony
or the volatile oxide is available. The use of crucibles and pot
furnaces precludes the possibility of working large quantities.
The roasted ore is fused with 10 per cent, of its weight of crude
argol, or with charcoal or anthracite and potash or soda, in crucibles
made of fire-clay, heated in a wind furnace or in a galley furnace.
The mould in which the melted metal is cast must be coated with
tallow or with a thin layer of fire-clay cream.
According to Knab, we have the following :—
One crucible contains 26*5 lbs. of roasted ore, with 10 per cent, of charcoal
and 7 '15 per cent, of salt or soda.
Pots are arranged 10 or 12 in each furnace.
Each pot turns out 4 or 5 charges in 24 hours.
Consumption of coal, 70 to 80 per cent, of weight of ore.
Life of each pot, 7 or 8 charges.
A new process * just discovered by Herrenschmidt consists of
melting, in a crucible, balls of the following composition :—
Antimony oxide.
Powdered anthracite.
Carbonate of soda.
Water.
The decided advantage of this process is that the "starring" of
the metal can be effected in a single operation.
The furnace used is shown in fig. 53.
2. Extraction of Metallic Antimony from Antimonium Crudum.
—This method is only applicable to rich ores and crude antimony.
The following process to be described involves the use of rich ore; if
crude antimony is under consideration, the composition of tho charge
* The author is under obligation not to give the details until tho patent is
taken.