antimony - Sciencemadness.org

THE METALLURGY OF ANTIMONY. 109
The starring of the metal can be brought about by using a purifying
mixture of 6 parts of carbonate of soda and 4 parts of antimony
trioxide, which has previously been melted in a small chamber at one
end of the reverberatory furnace. This mixture should be poured
out as soon as the metal is allowed to run into moulds.
(b) Reduction in Water-jacket or Blast Furnaces.—At Bouc and
Septemes, ores containing 30 to 40 per cent, of antimony were at
first roasted in reverberatory furnaces, and the roasted product was
reduced in three tuyered shaft furnaces which were worked on the
" spur " principle with covered " eye." Their dimensions were : height,
10 feet 10 inches; depth, 2 feet 7 inches to 3 feet; width, 1 foot
11 inches. In twenty-four hours 2 to 2 J tons of ore were worked, with
the consumption of one-half the weight of ore of coke. The crude
metal produced contained 92 to 95 per cent, of antimony, and was
refined.
Hering proposed to work the liquation products, with the composition
shown on previous page, in a circular shaft furnace of
the following dimensions :—
Height, 19 feet 8 inches.
Diameter at the tuyere level, 3 feet 4 inches.
Blast, 530 cubic feet per minute, at a pressure of 7'8 inches of water.
Residues melted, 7 tona.
Tap cinder added, 150 per cent.
Limestone used. 40 per cent.
Gypsum or Glauber salt, 5 per cent.
Coke consumption, 14 per cent
At Banya, near Schlaining, in Bohemia, antimony ores, consisting
of sulphides and oxides, mixed with a considerable proportion of
siliceous waste, are smelted in a blast furnace for crude antimony, which
is then refined in a reverberatory furnace.*
The average percentage composition of the materials charged into
the blast furnace is given in the table on page 110.
The furnace has a round stack 6 m. high, 1 *4 m. in diameter at the
throat, and 1 m. at the hearth, which is provided with five watertuyeres
and three outlets for the molten product — an upper one for slag,
and two at the bottom. One of these has a slight rise for tapping,
while the other, which is horizontal, is used for blowing out the furnace.
Blast, supplied by a screw-blower, gives 15 cb.m. per minute at
30 cm. water-pressure. The gases are collected by a tube leading
from the side of the furnace a short distance below the throat. The
* This is taken from Berg. u. htitt. Zlg.t 1886, p. 102, as translated by
Bauerman in his Elements of Metallurgy, p. 494.