The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1918-05-23
CIV. l.. Zeigler in Engineering
Mining JournaD

Nedriy ali Ilolatlon OILS, Wnen uSe'
In small quantity, show marked ten
dency to float galena in preference t.
sphalerite and pyrite. This is espe
cially true when the so-called "froth
ing" oils are used. The greater par
of the clean galena ores in the Coeul
d'Alene district float easily, with
good recovery, by the use of steam
distilled pine oil or wood creosott
which are good frothing agents but
poor collectors, while, with possib,
one exception, the sphalerte ores re-
quire a collector" to obtain a good
extraction. Much work has been done
In this district to separate the ga
lena and blende in the mill shines by
flotation. and at present this is being
accomplished in several mills and
tailings plants.
Pneumatic Cell Successfully Used.
The general method used at pres
ent is to float the galena first from
the thickened mill shines in pneumat-
ic cells by the use of small quaint
ty of frothing oil. The failing from
the lead cells is then sent to zinc cells.
where the sphalerite is floated from
the gangue by using suitable guam
tity of collector" oil and reagents
In this method. the type of flota-
tion machine employed probably has
as much to do with the success of the
process as have the differential prop
critics of the oils used The pneumat-
IL cell is particularly adapted to this
work, as the agitation is by no means
violent and can be readily adjusted to
meet different conditions by simply
supplying more or less air under the
airmats. Mechanical agitation will
invariably tend to raise the finer par
ticles of sphalerite with the galena,
and as froth produced in this man.
ner is much more persistent and diff
ficult to break down than that made
by the pneumatic cell, there is little
mechanical separation of the two sui
phides in the froth bed
When using wood creosote or pine
OIL blende forms more friable froth
than galena hence, in deep bed,
the froth breaks down, permitting
most Of the zinc to go back into the
pulp, while the greater part Of the
lead remains in suspension. This con-
dition is obtained when using small
quantity of air in the pneumatic cell
boards over the top or side rails on
the overflow edges to hinder the flow |
OF the froth, thus giving the zinc In |
the froth a chance to drop back into |
the pulp
Predominance of Metals Governs the
Concentrates.
The greatest disadvantage is that I
there is no sharp end point between
the flow of the lead and zinc froths,
and it depends to a large extent upon
the skill of the operator. However,
where conditions are regular, better
results are obtained than one would
naturally expect. The amount of zinc
that is contained in the lead concen-
trate and the amount of lead that is
left in the zinc concentrate depend
greatly upon the percentages of the
two minerals in the feed That is, If
the galena predominates in the feed,
it is easier to make high grade lead
concentrate which will carry a small
percentage of zinc than it is to obtain
a zinc concentrate that will carry
small percentage of lead, and the low
er the proportion of lead is to that Of
zinc, the more difficult 1t is to obtain
a clean lead concentrate and a high
extraction of galena.
Several combinations OF 'roughers"
and cleaners" may be used, accord |
ing to the values and characteristics I
of the ore, the extreme case being a
rougher and cleaner for both the lead
and zinc concentrate and tailings. At L
ter the lead is taken off, there is no
objection to using mechanical agita-
ton for extracting the zinc, and 1t is
sometimes used on the failing from {
traction. 6
The general mill practice is to car K
ry out ordinary concentration as far /
as possible, and to remove both a I
lead and zinc concentrate as coarse as 6
can be separated, depending upon the q
of the ore. The great c
ar part of the lead, and in some cases r
Of the zinc, are removed in this man i
ner, and flotation is used only for c
that is too fine or which can s
not be separated on tables and van g
ners 1t
Initial Preparation Of Pulp. Y
The initial preparation Of the pulp 3
plays an important part in differen-
tial flotation. Probab]' the most diff
icult separation to make is when
octh sands and slimeB of the differ
ent minerals are present. This is due 8
10 the fact that the finer the mineral O
particles are, the less oil and agita- a
lion 1t requires to float them; hence,
i il hard to differentiate between the
fhe particles Of sphalerite and the
coarse grains of galena. The ideal
condition is when all the galena Is