A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...
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100 THE METALLURGY OF ANTIMONY.<br />
With ores containing 18 to 20 per cent, of antimony, 4J tons per<br />
twenty-four hours can be treated, with a consumption of 5 to 6 per<br />
cent, gas coke or 7 to 8 per cent, charcoal.<br />
The gold, if present in the quartz of the ore, is almost all recoverable<br />
from the scoria.<br />
For each apparatus four workmen are employed in the twenty-four<br />
hours, and 3 H.P. is used for the ventilators and pump.<br />
(6) The working conditions.—The best size of ore to be treated<br />
is from 1 to 4 centimetres. The ore dust must be separated<br />
out and, if in large quantity, can be moulded with 7 to 8 per<br />
cent, of clay into balls of the proper size and charged along with<br />
the ore.<br />
(c) The actual working is thus:—The roasting furnace is at first<br />
charged with old scoria up to a height of about 10 centimetres.above<br />
the uppermost iron bar forming the bottom ; then enough wood and<br />
charcoal are put in to a height of another 10 centimetres; as soon<br />
as they are lighted and burn freely, another charge of 300 kgs.<br />
of old scoria, mixed with 6 per cent, of charcoal, is put in; and,<br />
finally, when the burning is thorough and the furnace is hot, a<br />
charge of 50 kgs. of ore (containing about 15 to 20 per cent.<br />
Sb) mixed with 2 kgs. of charcoal is put in, and this is continued<br />
until the furnace is full to within 30 centimetres from the mouth.<br />
The same charge is continued every 12 to 14 minutes, according to<br />
the rate of revolution of the ventilators—which is from 1200 to 1400<br />
revolutions per minute—and the scoria is discharged accordingly.<br />
Gas coke gives better results, if it is obtainable; and, if it is used,<br />
only 2 to 6 per cent., or 1 to 3 kgs. for every 50 kgs. of the same<br />
class of ore, are necessary, according to the richness of the ore<br />
roasted.<br />
The temperature of roasting should not be more than 400° C.<br />
Water used per day for one apparatus is 30 cubic metres.<br />
(4) Results of the Experiments, (a) First Experiment.—The furnace<br />
was lighted at 8.30 a.m. on the 24th of April, and it was not until<br />
10.5 a.m. that the furnace was hot enough to admit the first charge.<br />
The working was continued- regularly until 11 p.m. of the same<br />
day; the total working time was therefore 12 hours 55 minutes.<br />
The charging was as follows :—Each charge consisted of 50 kgs.<br />
of ore, minus the ore dust, which had previously been sieved off.<br />
The first three charges were mixed with 10 per cent, of charcoal,<br />
the fourth-to the tenth charges with 4 per cent., the eleventh to the<br />
nineteenth with 2 per cent., and from the nineteenth to the last<br />
with 4 per cent. The total charges amounted to 2850 kgs. of ore.