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
A description of the process is as follows:--“The ore is crushed to a
certain fineness, depending on the character of the gangue. It is then
placed in leaching vats, with false bottoms for filtration, similar to
other leaching plants. A solution of cyanide of potassium and other
chemicals of known percentage is run over the pulp and left to stand a
certain number of hours, depending on the amount of metal to be
extracted. It is then drained off and another charge of the same
solution is used, but of less strength, which is also drained. The pulp
is now washed with clean water, which leaches all the gold and silver
out, and leaves the tailings ready for discharge, either in cars or
sluiced away by water, if it is plentiful.
“The chemical reaction of cyanide of potassium with gold is as follows,
according to Elsner:--
₂Au + ₄KCy + O + H₂O = ₂KAuCy₂ + ₂KHO.
That is, a double cyanide of gold and potassium is formed.
“All filtered solutions and washings from the leaching vats
are saved and passed through a precipitating ‘box’ of novel
construction, which may consist either of glass, iron or wood,
and be made in any shape, either oval, round, or rectangular--if
the latter, it will be about 10 ft. long, 4 ft. wide and 1 ft.
high--and is partitioned off lengthwise into five compartments.
Under each partition, on the inside or bottom of the ‘box,’ grooves
may be cut a quarter-to a half-inch deep, extending parallel with
the partitions to serve as a reservoir for the amalgam, and give a
rolling motion to the solution as it passes along and through the
four compartments. The centre compartment is used to hold the lead
or other suitable anode and electrolyte.
“The anode is supported on a movable frame or bracket, so it
may be moved either up or down as desired, it being worked by
thumb-screws at each end.
“The electrolyte may consist of saturated solutions of soluble
alkaline metals and earths. The sides or partitions of each
compartment dip into the mercury, which must cover the ‘box’ evenly
on the bottom to the depth of about a half-inch.
“Amalgamated copper strips or discs are placed in contact with
the mercury and extended above it, to allow the gold and silver
solution of cyanide to come in contact.
“The electrodes are connected with the dynamo; the anode of
lead being positive and the cathode of mercury being negative. The
dynamo is started, and a current of high amperage and low voltage
is generated, generally 100 to 125 amperes, and with sufficient
pressure to decompose the electrolyte between the anode and the
cathode.
“As the gas is generated at the anode, a commotion is created
in the liquid, which brings a fresh and saturated solution of
electrolyte between the electrodes for electrolysis, and makes it
continuous in its action.
Public-domain text, read in full here on John Shaqi.
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