Lead Smelting and Refining, With Some Notes on Lead Mining
Science
Lead Smelting and Refining, With Some Notes on Lead Mining
Lead -- Metallurgy; Lead mines and mining
The system of smelting was analogous to that which was practiced
in Wales rather than to the Silesian, the charges being worked off
quickly, and with the aim of making a high extraction of lead directly
and a gray slag of comparatively low content in lead. The average
furnace charge was 3500 lb. At the beginning of the reaction period
about 85 to 100 lb. of crushed fluorspar was thrown into the furnace
and mixed well with the charge. The furnace doors were then closed
tightly and the temperature raised, the grate having previously been
cleaned. At the first tapping about 1200 lb. of lead would be obtained.
A small quantity of chips and bark was thrown into the lead in the
kettle, which was then poled for a few minutes, skimmed, and ladled
into molds, the pigs weighing 80 lb. The skimmings and dross were
put back into the furnace. The pig lead was sold as “ordinary soft
Missouri.” The gray slag was raked out of the furnace, at the end of
the operation, into a barrow, by which it was wheeled to a pile outside
of the building. Shipments of the slag were made to other smelters from
time to time, 95 per cent. of its lead content being paid for when its
assay was over 40 per cent., and 90 per cent. when lower.
Each furnace was manned by one smelter ($1.75) and one helper ($1.55)
per shift, when two shifts per 24 hours were run. They had to get their
own coal, ore and flux, and wheel away their gray slag and ashes. In
winter, when three shifts were run, the men were paid only $1.65 and
$1.50 respectively. There was a foreman on the day shift, but none at
night. The total coal consumption was ordinarily about 0.8 to 0.9 per
ton of ore. Run-of-mine coal was used, which cost about $2 per ton
delivered. The coal was of inferior quality, and it was wastefully
burned, as previously referred to, wherefore the consumption was high
in comparison with the average at Tarnowitz, where it used to be about
0.5 per ton of ore.
The chief features of the practice at Desloge are compared with those
at Tarnowitz, Silesia and Holywell (Flintshire), and Stiperstones
(Shropshire), Wales, in the following table, the data for Silesia and
Wales being taken from Hofman’s “Metallurgy of Lead,” fifth edition,
pp. 112, 113.
Public-domain text, read in full here on John Shaqi.
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