Getting Gold: A Gold-Mining Handbook for Practical MenJohnson, J. C. F. (Joseph Colin Francis)
History
Getting Gold: A Gold-Mining Handbook for Practical Men
Johnson, J. C. F. (Joseph Colin Francis)
Gold mines and mining
The first point, then, is to effectively crush the gangue, the degree of
fineness being regulated by the fineness of the gold itself. This being
done, then comes the question of saving the gold. If the quartz be
clean, and the gold unmixed with base metal, the difficulty is small.
All that is required is to ensure that each particle of gold shall be
taken up by the mercury. The main object is to arrest the gold at the
earliest possible stage; therefore, if you are treating clean stone
containing free gold, either coarse or fine, I advise the use of mercury
in the boxes, for the reason that a considerable proportion of the gold
will be caught thereby, and settling to the bottom, or adhering to
amalgamated plates in the boxes, where such are used, will not be
afterwards affected by the crushing action, which might otherwise break
up, or “flour,” the mercury. On the whole, I rather favour the use of
mercury in the box at any time, unless the ore is very refractory--that
is, contains too great a proportion of base metals, particularly
sulphides of iron, arsenic, &c., when the result will not be
satisfactory, but may entail great loss by the escape of floured mercury
carrying with it particles of gold. Intelligent experience will assist
the battery manager to adopt the right system.
The crushed stuff--generally termed the “pulp”--passes from the boxes
through the “screens” or “gratings,” and so on to the “tables”--_i.e._,
sheets of copper amalgamated on the upper surface with mercury, and
sometimes electroplated with silver and afterwards treated with mercury.
Unless the quartz is very clean, and, consequently light, I am opposed
to the form of stamper box with mercury troughs cast in the “lip,” nor
do I think that a trough under the lip is a good arrangement, as it
usually gets so choked and covered with the heavy clinging base metals
as to make it almost impossible for the gold to come in contact with the
mercury. It will be found better where the gold is fine, or the gangue
contains much base metal, to run the pulp from the lip of the battery
into a “distributor.”
The distributor is a wooden box the full width of the stamper box or
mortar, having a perforated iron bottom set some three to four inches
above the first copper plate, which should come up under the lip. The
effect of this arrangement is that the pulp is dashed on to the plate by
the falling water, and the gold at once coming in contact with the
mercury begins to accumulate and attract that which follows, till the
amalgam becomes piled in little crater-shaped mounds, and thus 75 per
cent. of the gold is saved on the top plate.
Public-domain text, read in full here on John Shaqi.
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