The second and third qualities of ore are taken direct to the smelting
works; and where these are situated at some distance from the mines, as at
Huanchaca and Guadalupe, the transport is effected by means of strong but
lightly built iron carts, specially constructed to meet the heavy wear and
tear consequent upon the rough mountain roads. These two classes of ores
are either treated separately, or mixed together in such proportion as is
found by experience to be most suitable for the smelting process.
On its arrival at the reduction works the ore is taken direct to the stamp
mill. At the Huanchaca works there are sixty-five heads of stamps, each
head weighing about 500 lb., with five heads in each battery, and crushing
about 50 cwt. per head per twenty-four hours. The ore is stamped dry,
without water, requiring no coffers; this is a decided advantage as
regards first cost, owing to the great weight of the coffers, from 2 to 3
tons--a very heavy item when the cost of transport from Europe at about
50_l_. per ton is considered. As fast as the ore is stamped, it is
shoveled out by hand, and thrown upon inclined sieves of forty holes per
lineal inch; the stuff which will not pass through the mesh is returned to
the stamps.
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