A recent patent (U. S. patent 1,157,693, dated Oct. 13, 1915) to the Carborundum Co.1
aims to perform the three stages in the contact process in one
operation. The invention consists of an acid-proof pipe with permeable
carborundum diaphram, upon which platinum is deposited in the ordinary
way, which can be maintained at a constant temperature by electrical
energy, and which not only acts as a catalyzer but also heats the gases
to the temperature necessary for most effective yield of sulphuric acid.
MINING AND METALLURGY OF PLATINUM.
GENERAL CONDITIONS.
The
saving of crude platinum in the ordinary operations of placer mining is
not efficient. In fact, it would appear that platinum is saved in many
operations more by accident than by design. The recovery of the
individual metals of the platinum group, which are ordinarily found
alloyed in varying proportions in nature, is a problem for the expert
metallurgist or chemist, and can not be accomplished with any degree
of satisfaction by persons unacquainted with the intricacies of the
process.
The
following notes are compiled from various sources in response to
frequent demands upon the Survey for information on methods of mining
platinum and treating the crude material. They are accompanied by
citations to some of the more important articles published, and are
offered to give the layman a starting point in his investigations.
Most
of the refined platinum and allied metals produced in the United States
is obtained in the electrolytic refining of gold bullion and blister
copper. Crude platinum is obtained from the California and Oregon
placer mines, and this also needs to be refined. In discussing the
metallurgy of the platinum metals, therefore, we have to deal first
with the mining of crude platinum, next the electrolytic refining of
gold and copper, and finally the chemical methods for separating the
metals of the platinum group from one another.
PLACER RECOVERY.1
The
platinum recovered in placer work in the United States is of secondary
importance. The gravel deposits are worked mainly for the gold they
contain, and the saving devices used are designed chiefly with this in
view. Mechanical improvements to overcome difficulties in saving fine
gold and platinum are also in use at some of the mines.
In
general, the crude platinum of the western placers is found in
relatively small scales or flakes, some larger than one-eighth inch in
diameter, but the majority less than one-sixteenth inch in size, many
being under one thirty-sixth inch. These flakes, like flakes of gold,
have a tendency to elude capture in the ordinary miner's sluice, and
probably a large part of the flake gold and platinum has heretofore
been carried in suspension to tailing piles. Undercurrents in the
