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

118 THE METALLURGY OF ANTIMONY.
sulphide on the hearth of a reverberatory furnace. After the hot
ore has been charged and thoroughly rabbled, iron is added, the
temperature of the furnace raised, and, when the decomposition is
complete, the antimony tapped; the tap-hole is closed as soon as the
iron sulphide appears. Slag is drawn through the working doors;
and the increase of iron sulphide obtained during the operation is
removed until the bath is reduced to its original depth. This method
is said to have given good results, and has been in successful
operation for more than a year.
Cookson patented* in 1902 a process very similar to that of
Sanderson. In fact, Cookson's and Sanderson's patents are copies of
a similar patent by Herrenschmidt (No. 296,200, Jan. 16, 1900,
France), shown in fig. 54.
(b) Water-jacket or Blast Furnaces.—Hering has experimented
with shaft furnaces for the treatment of liquation residues by the
precipitation method. 'Although his experiments have not been
continued, yet good results might be obtained if rich ores were
treated.
According to Herrenschmidt, rich ore can be treated directly in a
water-jacketed furnace. Temperature = 1000° to 1100° C. Airblast
=10 c. of mercury. About 12 to 14 per cent, of antimony
can be recovered from the condensing chambers. Coke used = about
300 kgs. per ton.
(c) Converters.—According to Germot, t sulphide ore can be smelted
in a converter into which air is blown. The air burns part of the
sulphur of the ore, with the production of sulphurous acid and the
metal itself. The operation is made continuous by the addition of
more ore. The sulphurous acid produced escapes through a pipe at
the upper part of the converter, together with the antimony sulphide
fumes. If a current of air is made to act on these fumes, oxysulphide
or antimony oxide will be produced, according to the amount of air
admitted.
The products of the extraction of crude antimony J are unrefined
antimony and slags. The former contains many foreign elements, as
shown in the analyses given in the table on p. 120.
This impure antimony has to be refined. The slags obtained from
* French patent No. 324,864, Sept. 30, 1902.
t A. Germot, Revue des Produits Chimiques, Dec. 15, 1907. Similar to Herrenschmidt's
French patent No. 333,340, June 24, 1903.
t The term "crude antimony," meaning the unrefined metal, must be disinguished
from the teim "antimony crude,*' which means the liquated antimony
sulphide.