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

THE METALLURGY OF ANTIMONY. 77
fuel is dear and the cost of mining is low, and where it is a question
of producing large quantities of crude antimony with great rapidity.
Thus, under these special conditions the loss of the sulphide may be
practically neglected.
The construction of such a reverberatory furnace is that of the
ordinary type, with the exception that there must be present a taphole
at the deepest point of the bed for the removal of the liquated
sulphide.
Figs. 9,10, 11, 1- show the construction of a liquation reverberatory
furnace.
The inevitable loss in tubes an4 in reverberatory furnaces can be
prevented by using the condensation apparatus of Herrenschmidt.
Products of Liquation.—The crude antimony thus produced
generally contains some impurities (1 to 4 per cent, of iron sulphide
and 0*2 to 3*4 per cent, of arsenic sulphide).
The following is an analysis of a liquation residue given by Bruno
Kerl :—
Sb«S;.* 20*40
FeS 2-S7
FeS» 1-23
SiO. . 59-S4
AloO, 4-65
CaO 5"12
C0.2
4*10
Alkali and uurboiiaceuiia niu-iter . . . 1*69
The liquation residues, if sufficiently rich, are worked up for
antimony regulus.
2. Preparation of the Stable Tetroxide.—Since the sulphide and
the oxide of antimony ore are not mutually decomposed on heating, as
are the sulphide, oxide, and sulphate of lead in the preparation of
the metal from galena, a roasting and reaction process cannot, therefore,
be used for the winning of antimony from its ores. "When
sulphide and oxide of antimony are melted together, a glass of oxysulphide
is formed. Antimony tetroxide can only be reduced to the
trioxide in the presence of the sulphide, while at the same time
antimony glass is formed.
An oxidised ore is generally mixed up with the roasted sulphide
for the reduction process; and any ore, when sulphuretted, is worked
together with antimony glance.
*The Sb2S3 is not only found in the interior of the pieces, but covers them
with a film of thin glaze.
100