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Патент USA US2406820

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. Sept- 3, 1946-
H. F. FISHER‘ETAL
2,406,320
METHOD FOR REMOVING SUSPENDED MATTER FROM SUSPENSIQNS
‘Filed April 19, 1945
/2
INVENTORS.
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Patented Sept. 3, 1946‘
2,406,820
UNITED STATES PATENT OFFICE‘W
‘ METHOD FOR REMOVING SUSPENDED‘
MATTER FROM SUSPENSION S
Harmon F. Fisher, Palo Alto, and 'Albert C. Peck,
‘ ‘
‘Los Altos, Calii, assignors, by mesne assign
ments, to The Permanente Metals Corporation,
.
a corporation of Delaware
" Application April 19, 1943, ‘Serial No. 483,564
4 Claims.
7
This invention relates to the separation of
suspensions and moreparticularly to a method
and apparatus for’ recovering ?nely divided cur
rent~conducting solids, such as metal or carbon
particles, from suspensions containing such par
ticles dispersed in non-conducting liquids. With
regard to its still‘ more speci?c features the in
vention relates to the recovery of ?nely divided
magnesium particles from suspensions thereof in
hydrocarbons.
(or. 204-184)‘
2
1
’
I
‘
‘
In the course of manufacturing magnesium by
the carbothermic reduction of magnesium oxide
containing prime materials the mixture of mag;
provide a method and means for enabling two
phase systems of the kind in question to be sep
arated with the attainment of the most favorable
degreeof concentration of the solid phase.
In general, the method according to the inven
tion comprises the following steps in continuous
. succession: cataphoretically depositing the sus
pended matter on a, preferably mobile, deposit
ing ‘electrode, ‘by establishing a unidirectional
l0 electric ?eld between said electrode and a second,
preferably stationary, ionizing electrode; then
withdrawing the deposit formed from said elec
tric ?eld, and subjecting it to the action of means
nesium vapor and carbon monoxide issuing from
‘capable of mechanically driving out therefrom
the reduction furnace‘has to be cooled down very 15 part of the included liquid; thereupon introduc
suddenly to below, advantageously far below, the
ing the so treated deposit into a heating zone;
solidi?cation point of magnesium, to avoid rever
and ?nally removing the deposited matter from
sion of the reaction. As a consequence thereof
the magnesium is condensed in the form of dust
of very ?ne subdivision.‘ Yet magnesium dust
thus produced, owing to the extensive'reaction
surface presented by the ?nely divided metal, is
highly reactive and‘ even pyrophoric. For pre
venting dust of such a kind'from reacting with
the oxygen and nitrogen of the air, ‘the art has
resorted to covering the particles with a protec
the depositing electrode.
'
'
In the annexed drawing an apparatus capable
of performing the said method is represented.
Fig. l is a somewhat diagrammatic view in side
elevation of the apparatus embodying the inven
tion; Fig. 2 is a detailed top view of a gas blast
device forming an essential part of the appara
25 tus; Fig. ,3 is a sectional view taken on the line
.-':-3 of Fig. 2.‘
'
a
tive liquid, and the use of liquid hydrocarbons
In the embodiment of the invention illustrated
for the purpose has proved rather successful;
in the drawing, the apparatus is provided with
However, considerable diiflculties are‘ encoun
a,‘ preferably gas-tight, ‘casing I held in position
tered in eventually recovering the metal parti 30 by supports (not shown). Said casing contains
cles from the liquid, seeing that the slurry
a drum-shaped electrode 2 constituting a depos
formed cannot’ be I separated by conventional
measures such as settling, centrifuging, ?ltration.‘
Thesame problem arises in case hydrocarbons in
themselves are used as the chilling medium.‘
iting surface, the drum being rigidly mounted on
a horizonta1 shaft 3 and rotated by means of said
shaft. Also contained within the casing l is a
system of ionizing electrodes 5 of semicircular
form‘ concentrically surrounding a segment of
the cylindrical surface of the drum, which ioniz
ing electrode system is‘ connected with a source
of electric potential and disposed adjacent to and
In a prior Patent No. 2,376,535, issued May 22,
1945, ?led on December 22, 1941, by Harmon F.
Fisher, one of the joint inventors of the present
application, it has been proposed to disjoin sus
pensions of the kind in question by a method 40 spaced from the cylindrical drum surface at a
which includes in continuous‘succession the steps
suitable distance, according to the applied volt
of cataphoretically depositing the suspended
ages, so as to establish a unidirectional electric
matter on an electrode, preferably consisting of
?eld‘ of su?icient intensity between the depositing
a rotary drum, by establishing a unidirectional
and ionizing electrodes. The ionizing electrode
electric ?eld between said electrode and a second 45 system is electrically insulated ‘from the cylin
ionizing electrode, then withdrawing the deposit
drical drum surface.
,
from said electric ?eldv and subjecting it to the
An optional form of ionizing electrode system
influence of heat-emitting means, and ?nally re
comprises,‘ in a manner well known per se, units
moving the deposited matter from the depositing
including a plurality of sharp pointed rods 5
electrode. The present invention aims at im 50 uniformly spaced with respect to each other and
proving the' method of .said prior application,
substantially perpendicularly directed toward the
with the View of securing, ‘for a given size of ap
depositing ‘electrode surface. Several groups of
paratus, the highest separating capacity obtain
semicircular electrode units of this kind, for'in
stance three or ?ve, are uniformly positioned
Accordingly, it is an object of this invention to 55 along-the'entire width of the depositing electrode
able.
‘
‘
‘
2,406,826
3
4
surface 2, one beside the other at suitable in
tervals.
To cause the suspension to be treated to flow
drum. By such a reuse in cycles of an indifferent
gas the drying of the deposited material is
markedly improved.
The operation of the apparatus is as follows:
on, in the form of a ?lm, to the cylindrical sur
The suspension, for instance, containing as the
face of the drum electrode 2, there is provided
solid phase ?nely divided magnesium particles
within the upper part of the casing a feed pipe
accompanied by a certain amount of magnesium
6 that opens into a nozzle 1 situated adjacent to
and appropriately spaced from the surface of the
oxide- and carbon particles is uniformly intro
drum and extending the whole width thereof.
duced across the surface of the rotating drum
Advantageously the axis of said nozzle forms an 10 electrode 2. The solid particles are separated
angle of about 45° with the horizontal plane_
out of the suspension under the in?uence of the
Behind the said feed inlet (in the direction of
electric ?eld established between the electrodes,
the rotation of the drum), there is positioned a
and are deposited on the surface of the rotating
sort of gas blast device 8 that is appropriate for
drum, whereas the liquid phase ?ows down to the
applying a forcible stream of gas to the adjacent 15 collecting pan 16, substantially perfectly freed
drum surface in countercurrent to the direction
from the solids. During the progressing rotation
of rotation. As is shown in Fig. 2, a gas inlet 9
of the drum the deposit is subjected to a pri
is connected to a manifold [0 with a mouthpiece
mary treatment that is effected by causing it to
ll provided with a slot l2, which extends the
pass beneath the forcible gas stream impinging
whole width of the drum. The gas blast 8 per 20 thereon in countercurrent to the direction of ro
forms the function of skimming o?f the liquid
tation. The gas charged must be indifferent to
adhering to the surface of the drum and remov
metallic magnesium such as in ?rst instance hy
ing included liquid from the matter deposited
drogen and helium, or other hydrocarbons and
thereon. Experiments have shown that the
natural gases containing hydrocarbons as main
degree of concentration brought about by the gas 25 components. The concentrating action is then
blast increases in direct relation to the velocity
continued during the passage of the drum
of the gas stream issuing from the mouthpiece;
through the heating zone, whereupon the dried
it is therefore advantageous to provide the same
material is removed, by scraping, for further re
with a narrow-slotted ori?ce. The slot I2 may
?ning treatments.
be so positioned in relation to the surface of the 30
By the combined action of means capable of
drum that the gas stream is directed to the ap
skimming off adhering liquid and blowing in~
proaching surface perpendicularly or at any other
eluding liquid from the deposit and of successive
desired angle.
Behind the blast pipe 8 (in the direction of
. ly applying heat thereto by radiation or con
vection or both, a higher degree of concentration
rotation of the drum) are situated radiant heaters 35 can be produced than was heretofore attainable
l3 concentrically surrounding a segment of the
in an uninterrupted operation.
drum surface the area of which is large enough
The electric potential between the electrodes
to allow the deposit to be further concentrated,
should preferably be just below the break-down
potential for the electrode spacing. The polarity
At a point approximately diametrically op 40 of the electrodes does not have any major effect
posite to the blast pipe 8 one or more flexible
on the functioning of the separator, although
scrapers M, advantageously wire brushes, are
the indications are that with the separation of
provided so as to contact the width of the cylin
magnesium the best operation is obtained when
drical surface of the rotating drum. Directly
the pointed outer electrodes are negative with
thereunder is positioned a funnel system 15
respect to the drum.
adapted to catch and withdraw the treated solids
We claim:
scraped loose from said surface.
1. The method of separating ?nely divided
Directly below the rotary drum at the side of
electrically conducting solids from suspensions
the drum at which the suspension to be treated
thereof in non-conducting liquids which com
by drying, while passing underneath.
is fed on, there is positioned a trough or launder
prises, passing a slurry of said suspension onto a
£6 with an outlet H for collecting and with
continuously moving electrode, cataphoretically
drawing the cleared liquid phase.
In order to enhance the drying action obtain
able by the application of radiant heat, it is ad
depositing the ?nely divided solids thereon by
the effect of a unidirectional electric ?eld be
tween said electrode and a second ionizing elec~
vantageous to cause a stream of hot gases to
55 trode of opposite polarity, withdrawing the elec
move over the material deposited on the drum.
trode from the electric ?eld, blowing included
For this purpose an inert gas, such as hydrogen,
liquid from the deposit by subjecting it to the
methane or natural gas, is passed under a suitable
action of a jet of high pressure gas, and then
hood l8 positioned adjacent to the outside sur
removing the deposit from the electrode.
face of the radiant heater I 3 and spaced there
2. The method of separating ?nely divided
60
from to form a duct, the lower end of which
magnesium from suspensions thereof in non-con
turns inward so as to cause the gas to flow up
ducting liquids which comprises passing a slurry
ward between the inside surface of the radiant
of said suspension onto a continuously moving
heater [3 and the drum 2 countercurrent to the
electrode, catapho-retically depositing the ?nely
direction of rotation of the drum. A blower 20 65 divided magnesium thereon by the eifect of a
with inlet and outlet pipes 2| and 22 is provided
unidirectional electric ?eld between said elec
above the casing I in such a position as to draw
trode and a second ionizing electrode of opposite
off the gas at a point in the neighborhood of the
polarity, withdrawing the electrode from the
apex of the casing I through pipe 2| and recir
electric ?eld, blowing included liquid from the
culate it through pipe 22 at the top of the duct 70 deposit by subjecting it to the action of a jet
l8 periodically. On ?owing downward through
of high pressure gas, and then removing the de
duct Hi the gas is heated and on being moved up
posit from the electrode.’ >
ward along the inside surface of the radiant
3. The method of separating ?nely divided
heater I3 it continuously supplies additional heat
carbon from suspensions thereof in non-conduct
to the matter depositedron the surface of the 75 ing liquids which comprises passing a slurry of
r.
J
2,406,820
said suspension onto a continuously moving elec
trode, cataphoretically depositing the ?nely di
6
?nely divided solids thereon by the e?ect of a
unidirectional electric ?eld between said elec
trode and a second ionizing electrode of opposite
vided carbon thereon by the effect of a unidi
polarity, ?owing hydrocarbon from the deposit
rectional electric ?eld between said electrode and
a second ionizing electrode of opposite polarity,
under the in?uence of gravity, withdrawing the
withdrawing the electrode from the electric ?eld,
electrode from the electric ?eld, blowing included
liquid from the deposit by subjecting it to the
blowing included liquid from the deposit by sub
action of a jet of high pressure gas, introducing
jecting it to the action of a jet of high pressure
gas, and then removing the deposit from the
the so treated deposit into a heating zone to
10 further remove included liquid by evaporation,
electrode.
and then removing the deposit from the deposit
4. The method of separating ?nely divided
electrically conducting solids from suspensions
ing electrode.
thereof in hydrocarbon liquids which comprises,
HARMON F. FISHER.
passing a slurry of said suspension onto a rotat
ALBERT C. PECK.
ing electrode, cataphoretically depositing the 15
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