The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1919-04-17
monty used are the Oliver Portland

monty used are the Oliver, Portland
Kelley and American. The moisture
content of the final product after I'LL
tration varies from about to Is Pc
that are not filtered. but are simply
thickened In tanks. usually contain Is
10 rs per cent moisture. A reduction
In moisture content TO 3 or 4 per cent
would be very desirable for plants
having high freight charges, owing to
the length of haul to the smelter. The
commercial possibilities Of effecting
such reduction In moisture content.
whether by means Of some type of
drying furnace. such as the Lowden
patented drier, or by use of drier in
combination with vacuum filter. as
suggested by p S. Handy, would de-
pend upon the cost of treatment and
the saving In freight charges.
Mill Products.
II has been stated that the chief
metals produced in the mines OF the
Occur d'Alenes region are lead and
zinc, with minor amounts OF copper
silver and anthony. Where the lead
zinc iron minerals are as finely dis
seminated as in the ores mined in the
Pine creek, Nine Mile and other dis
tricts, 1t Is next to impossible to make
clean products Of lead and zinc by fhe
usual gravity concentration methods
Although good percentage Of both
lead and zinc concentrates is obtain.
ed from the jigs at most mills, fine
grinding Is essential to make fairly
clean separation of either mineral
from the finely disseminated ores Of
this character. In fact, 1t has been
found, In examining material finer
than 200-mesh under the microscope,
that some of the lead and zinc parti-
cles were still mechanically combin-
ed. The following examples will give
some idea of the kind Of ore treated
and the products obtained by present
methods of concentration. (Here 'ol
lows tables showing kind Of ores
treated and concentration products In
mills Of the Occur dAfene region).
1t is apparent from the above exam
pies that there is considerable loss
Of zinc in the lead concentrates, and
no small amount Of lead in the zinc
The question arises,
therefore, as to whether or not clos
err separation Of the minerals is COM
mercially feasible. Granting that n
cleaner product Is feasible, what steps
should be taken to effect a closer sep
aration, whether a. by changes and
II possible. in the ex-
listing equipment. such as the install
alton of a finer grinding system when
would require more tables, possibly
smaller number of jigs, and some
what larger flotation plant. or t2) by
a combination Of Cd and differentiai
flotation, or (3) by giving the con-
centrates a flash roast followed ny
flotation, or a. by some
hydrometallurgical process?
To avoid radical changes In the
equipment in the mills and in the
methods used, it uwold seem advis-
able to carry on research work along
the lines Of "a and (2), namely, to
effect a better separation by differen-
tial flotation, with whatever changes
in the present treatment of the ores
this might necessitate, should differ
entail flotation prove successful.
Ut is along these lines, therefore,
that the bureau of mines, in cooper
alton with the University Of Idaho
and mine operators Of the state, will
continue to put especial stress on
finding some method by which bet
ter commercial separation will be pos
sible. From the number Of tests run
to date. it is gratifying to state that
some very interesting and encourage
ing results have been obtained.