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

THE METALLURGY OF ANTIMONY. 83
a reverberatory furnace), as used iu New Brunswick, are as
follows:—
Length 42' 6"
Width . . . . . . . . 7' 6"
Working doors on each skie . . . . , 10
Height from bed to roof 2' 1"
Width of fire-grate 2'1"
Height of fire-bridge 5'2"
Breadth of fire-bridge 1"
The method of working is as follows :—
Capacity of furnace . . . . . . 30 cwta.
Charges . . . . . f» to o ewts. at one time.
S charges (18 cwts.) during 24 hours, so that
each charge remains in the furnace for 40
! hours.
Consumption of) m. A . -,.«,,
wood j" Three-quarters of a cord m 24 hours.
Loss of Sb 7*5 percent.
The ore must be strongly heated, and thoroughly rabbled every five
minutes during the last two hours before being drawn. Properly
roasted ore must have a dull grayish-yellow colour.
The furnaces, as used at Banya, have the following dimensions:—
Length . . . . * 26' 3"
Width 6' 6"
Working doors on each side 5
Ores roasted in 24 hours 24 cwts.
Charges of 4 cwts. each are introduced at the colder end of the
furnace, and are then finally drawn after twenty hours at the opposite
end. Stepped grate is used, and the fuel is lignite.
The following operation for roasting the ore is carried out in
Tus % cany, Italy:—200 kilos, are charged into a reverberatory
furnace, heated up a little previously. The temperature is then
raised to not more than 350°. Rabbling is carried on for from three
to twelve hours. Rich ores require a longer time. Each operation
requires 35 kilos, of lignite, and the loss due to volatilisation is not
more than from 5 to 8*5 per cent.
Another type of the same kind of furnace is shown in figs. 19, 20,
21, 22.
Furnaces with a trough-shaped bed sloping towards one of the
longer sides of the furnace have been proposed for the performance
of both reduction and roasting at the same time. The use of having
the slope is for the tapping off of any portion of the sulphide tliat is
unavoidably liquated during the roasting.