The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-06-26
Macquisten Tube Flotation Process,
In Use at Morning Mill
O. Hofstrand Of Wallace in Mining Engineering World

Solid bodies will float In liquid
by reason Of lower specific gravity, or
of peculiar form. or of repellant ac-
|tion towards the liquid which prevents
Them from overcoming the resistance
lof it's surface tension. To the last Of
these causes the flotation of ores Is
Ito be ascribed. Nearly all ores and
lgangues are specifically heavier than
water, yet they do not behave alike
in this respect, and they may be d.
|vided into two classes, those of flotable
land non-fotable minerals respectively.
Fiotable and Non. Flotable.
Upon close examination Of these
two groupes of minerals we find that
those particles that Will float on the
|surface of water are close grained,
have metallic, resinous, waxy or shin
Ing luster, and are water repelant.
while the particles which sink are
usually porous. have dull, earthly.
non-metallic luster, and are water abb
lsorbent, 1t Is also further observed
that the fiotable particles are usually
Isulphides while the non -fiotable par
ticles are usually oxides. carbonates,
and gangues. By taking advantage of
these facts separation can be success
fully made between these classes
without respect to the specific gravity
of either
In order to secure the flotation of
suitable particles. they must be pro-
lperly introduced to the surface of the
water, SO as not to break it.; surface
tension. Important factors are, the
Isize of the particles. the angle Of in
production to the surface, which varies
with the size of the particles, the velo-
lefty Of the particles. and an inter-
|mittent application of air to the par
Iticles.
TIE Macquisten Tube.
After several years spent in invests
cations, the Macquisten tube con-
tcentrator embodying these factors,
was developed and perfected by A. p.
Is. Macquisten in Glasgow, Scotland.
The tube. which is the principal part
Iof this machine, is thin. cylindrical
shell 3-16 Of an inch thick, 6 feet long,
and S.5 inches in outside diameter.
Internally, the tube is cast with
helical corrugations (screw threads),
preferably of quardruple pitch, ad-
|vancing 3 inches with every turn
around the tube, the pitch between
|corrugations being o75 inch. The
form of corrugations, which has been
determined by much study and labor
plays very important part in pro-
|ducing flotation.
The tube rests horizontally on bab-
|bitted bearings at each end. The bear
ing at the feed end is concal- shaped
hollow bearing, through which the
feed is introduced. The discharge end
of the tube connects with cast iron
sand box composed of sand and
slime hopper the joint between the
sand box and the tube being water
tight. while the tube is free to revolve.
At the end of the sand box, directly
opposite the discharge end of the tube.
an opening Is cut for the overflow of
the surface water. carrying the float
ing material. At this point a weir
regulates the depth Of the water in the
tube. The sand box is equipped with |
an adjustable sphon on the slime hop |
per- by which the amount of water
overlooking the weir is regulated. The |
tube is equipped with machine-cut |
cast iron spiral gear at the feed end /
with teeth cut at an angle of 80 de-
grees to it's center line. and is driven
by a spiral pinion of steel with teeth
cut at an angle Of 60 degrees to it's
center line The pinion is mounted ON
a steel shaft and operates at right
angles to the tube.
The tubes are ordinarily erected In
sets Of eight In double series OF four.
md are supported on a steel channel
'rame and so arranged that the two
ubes in the same horizontal elevation
ire driven by the same shaft. Under ;
zach sand box is a secondary feed
pout which feeds the tailings from
ne upper tupe w TIE tuut ueiuW ~ III
he top tube only being equipped with
N initial feed spout which receives
he feed as 1t comes from the feed dis
ributors.
Operation Of Macquisten Tubes.
The operation of the tubes Is very I
nipple; the feed Is received through
he initial feed spout in the first tube;
moved forward by the aid Of the
thermal corrugations to the discharge
nd Of the tube; and in its advance is
speatedly carried from under the wa
II. where it rolls and slides back,
trough and on to the surface water.
nd the particles remaining on the
irface are carried over the discharge
cir In thin film bv the surface flow.
he minerals which adhere to the tube
nd are carried over to the opposite
de are introduced to the surface at
e same angle and are floated In the
me manner. The tubes are oper
ed most successfully at speed of
rpm, and In tubes that are cast
It'll quadruple thread the feed re-
aims in the tube for a period of 4S
conds before 1t Is finally discharged (
this point the taiings can either
sent to the creek depending on |