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

THE METALLURGY OF ANTIMONY. Ill
The first two are sent to be refined, and the last is taken back to
the blast furnace.
The relative proportions of the total production of the furnace:—
No. I. is 82-5
„ II. is 90
,, III. is 8*5
The slags vary in composition :—
I. II.
SiO2 46*9 45-9
CaO . . . . . . 34'6 31*4
FeO 151 19*9
Sb . . . . . . . 0-5 0*9
No. I. is obtained from mixture A, and No. II. from mixture B.
Calcination is effected in a reverberatory furnace. Length, 8 m.;
breadth, 2 m. Five working doors on each side. Heated with brown
coal upon a step-grate furnace. The production is 1200 kilos, per day.
The ore, charged in 200-kilo. lots, clots and softens, giving off a
large quantity of sulphurous acid as soon as it attains red heat, but
subsequently becomes dry and in the state of powder. The average
time for a charge to remain in the furnace is twenty hours.
The refining of the metal is conducted in a reverberatory furnace,
with an iron bed 4 m. long by 2*5 m. broad, covered with a layer of
fire-clay 0*28 m. thick. Brown coal is used upon an ordinary grate.
The furnace is provided with working doors on one side and tappinghole
at the end of the bed. The gases evolved are used to warm the
moulds before they are used. The charge is as follows :—
450 kilos. No. I. (coarsely broken).
50 ,, j, II- (in powder).
42 ,, sulphate of soda.
5 ,, charcoal dust.
150 ,, unroasted ore.
Operation lasts ten hours ; and a final slag is obtained by the addition
of 3*40 kilos, of carbonate of potash, 2*60 kilos, of carbonate of
soda, 1 kilo, of raw and 6 kilos, calcined crude regulus (liquated
sulphide of antimony), 12 kilos, of the same slag from previous operations.
The impurities of refined antimony are :—
As 0*330 percent.
Ye 0-052 „
Ag 0-006 „
S 0720 „
According to Herrenschmidt, the following process is possible with
the use of a water-jacket furnace.