Grant County herald. [volume] (Lancaster, Wis.) 1850-1968, 1922-06-21
MINE RESEARCH BUREAU
CREATES GREAT SAVING

Inc mine operators of the district
nave known for years that the loss
OF zinc and lead in the fine tailings
and sludge carried by the waste water
mas been large. Their efforts in try
ing to prevent this waste were un-
successful and they finally called
upon the U. S. Bureau of Mines at
Washington to investigate the prob
lem. In November 1920, the mine
operators and the Director of the Wis
consln Mining School met representa-
tlVes OF the Bureau of Mines and the
problem Of reducing this mineral loss
vas discussed. It was decided that the
work could be done in Platteville in
cooperation with the Mining School,
as it is located in the center OF
the mining district and through it's
faculty, library, and well equipped
laboratories, could render valuable
assistance in the work. The work was
begun shortly after January LIST, 1921,
and was completed September LIST.
Messrs. w. H. Coghill and c. o. An
Gerson Of the staff of the Mississippi
Valley station of the Bureau of Mines
were assigned to the work. They
first studied the present concentrating
practice to ascertain what minerals
were lost, the quantity, and the rea-
son for these losses. The present
practice is wet concentration by the
means of jigs. The recovery of zinc
and lead by this process is about 70
per cent, which seems low to a person
unfamiliar with the practice, but
which is a good recovery for jig con-
centration. The use of concentrating
tables in the Wisconsin district to
save the fine zinc and lead had been
tried repeatedly but failed because
Of the presence in the ore Of marcas-
ite, (FeS2 locally called "sulphur') :,
which is of practically the same speci-
fic gravity as the zinc sulphide and
therefore will not separate from the
zinc by table concentration, making
it impossible to produce a clean zinc
product.
After this preliminary study the
problem was to find a method for saw
ing the ore which was being lost.
Messrs. Coghill and Anderson found
that about 65 per cent Of the values
lost at the mills occurs in waste ma
terial which is finer than 20 mesh
(.0340 inches), and that this repre-
OOhCo O111J cOOuC ~ pei NCAAG VI IAAC
gross amount of tailings produced
They finally devised the plan of
screening the tailings to this size and
then treating this product on cOncen-
trating tables to produce a low grade
of zinc-lead-iron concentrate. This
concentrate is then treated by oil flo
tation, which process makes it posi-
BILE to separate the zinc, lead, and iron
minerals into distinct high grade
commercial products. The equipment
to be installed to carry out the above
operation is comparatively simple and
inexpensive, and the cost of operation
is low, so that the value of the waste
products thus saved will largely eX-
coed the cost of recovering them.
AS a result of this investigation at
the Mining School, it will be possible
to recover valuable products from
what has heretofore been waste ma
terial, amounting to over five hundred
thousand dollars per year. Aside
from the zinc and lead ores which
will be saved, there will be produced
large tonnage of clean, finely
ground limestone which is an excel
lent commercial fertilizer.