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Патент USA US2134154

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Oct.' 25, 1938.
Original Filed June 25, 1952
I "I
:i All‘!
Hays .
Patented Oct. 25, 1938
Harold .Hardy Smith, Parkview, Johannesburg,
Union of South Africa, assignor of three-fourths
to General Mining & Finance Corporation, Lim
ited, Johannesburg, Union of South Africa
Application June 25, 1932, Serial No. 619,309. ,Re-1
newed July 15, 1937. ‘In the Union of South
Africa July 27, 1931
6 Claims.
(01. 2094425)
The present invention relates to jigs for con
centrating ores and other materials.
The principal object of the invention is to con
struct a jig adapted for a large capacity per unit
of screen area, with a good recovery of the ?ner
concentrates and low dilution of the tailing, and
capable of handling a feed containing a wide
range of particle sizes.
‘The pulp travelling over a sieve bed from the
Fig. I is a vertical section.
Fig. II is an enlarged plan of a part of the ad
justable sieve rim.
Fig. III is a detached View of the vhead motion.
7 - Fig. IV» is a diagram relative to the head motion. ;
r The hutch consists of the conical vessel 2- hav
ing any appropriate outlet for concentrates such
as the goose-neck 3 extending from its lower part.
Around the top of the hutch is the annular tail
1 O feed point to the point of discharge tends toyin
crease in bulk due to the additions of hutch water
ings collecting launder 4 having an outlet'5. ‘
through the bed; and’if such increase of bulk re
sults in largely increased velocity of flow over the
bed, ?ne valuable particles are prevented from
15 settling and are lost.
Such increase of velocity and resulting loss can
be minimized by making the sieve in the shape of
a buddle, with feeding means at the centre and
boss 6 and arms ‘I: the circular upper and lower
peripheral discharge of the tailings; but in the
few known instances where this arrangement has
grids 8, 9 resting on and secured to they spider;
and the circular screen 10 between the grids. The
jig illustrated is intended to deliver concentrate
only through the sieve, the'bed accordingly con
sists of a lower layer II of ragging and an upper
layer l2 of ore. The ragging is retained in posi
tion by the cells of the upper grid 8. The similar
cells of the lower grid 9 constrain the water cur
been proposed it was embodied in ‘constructions
rentsfor vertical movement.v
which were inherently incapable of large outputs
The sieve is provided with a raised rim 13 to
retain the ore column l2. For adjusting the
and clean concentration.
According to one aspect of the present inven
tion, dilution of'the tailing by hutch waterv is
depth of the ore column there is shown a'sup
plementary rim adapted to be clamped to the 25
minimized and rapid movement of the material
over the bed together with high grade hutch con
rim l 3 so as to project to the desired height above
the latter. It comprises several arcuate sections
centrate is attained by constructing a‘ jig with a
circular sieve which is vertically reciprocated, is
3 O fed at the centre, and discharges the tailings at
its periphery.
VThe sieve comprises a spider consisting ofa
l4 (Figs. I and II) provided at‘ their adjoining
ends with lugs I5 and clamp bolts l6 bywhich
the sections. are drawn together to clamp onto 30
the rim [3. Between the lugs are soft rubber or
The invention provides a head motion for the
sieve such that, in each reciprocation, vsaid head
motion moves the sieve downward with constant
acceleration approaching a point beyond half the
like ?lling pieces I‘! which close the gaps between
the lugs I5 and so prevent ore from escaping
stroke, at which it attains its maximum velocity, ‘
A surge grid ‘ l8 is?xed in the hutch immedi
through.them,_whilst allowing the lugs tobe ad
justed towardsone another.
then said head motion suddenly retards it and re
ately below the sieve to prevent surging of the
verses it into the upstroke so that it attains its
hutch water between the inner and outer areas
- maximum velocity at less than half the stroke,
and said head motion then moves it with constant
deceleration toward the top‘ of its stroke, the
movement in each reciprocation being purely
The invention further provides a fluid tight seal
between a vertically reciprocating jig sieve and
the hutch; as 'by means of a rubber or other ?ex
of the sieve.
I9 is a strip of rubber secured at its edges re
spectively to the rim 'of the sieve and to the inner
rim 20 of the launder 4, and making a ?uid tight
seal between the sieve and the hutch. It is de
sirable to minimize as far as possible the tendency
of the‘ strip 19 to act as a water-plunger, since ‘
whilst in the case of a circular sieve discharging
such plungeraction tends toupset the action of
the reciprocating sieve. The strip l9v should
therefore approximate to a vertical position, but
such position often involves practical disadvan
tages, and it has been found that if, when fully
tailings at its edge, contamination of the hutch
product by the tailings is de?nitely avoided.
zontal of not less than aboutthirty degrees, it ,
ible strip having its edges secured respectively. to
said parts. In this way interference with the re
sults last described, by leakage of water or air
5 O between the sieve and the hutch, is avoided;
.A jig constructed according to the invention is
55 shown in the accompanying drawing in which I
extended, the strip makes an angle to thehori
will, when relaxed,'assume the S cross-sectional
form shown in which, the inward and outward 55
bulges aboutv equal one another and thus prevent
water being displaced.
been constructed with the following dimensions,
The boss 6 is secured to the vertical shaft 2|.
At the upper end of the shaft is an open cross
Length of lower toggle link 25 ___________ __ 10%
head consisting of the crossbar 22, side rods 23 Length of upper toggle link 24 __________ __ 6%
extending vertically therefrom andya cross bar Thickness of pitman between links ______ __ 31/2
24 carried by the rods 23.
Effective length of pitman ______________ __ 12
Said cross head accommodates the head motion
whereby the shaft 2| is'supported and recipro 'iEccentric stroke _______________________ __ 1%
7 Centre’ of shaft 34, % inch below the mid
10 cated vertically.‘ The head motion comprises them“
point between the adjacent ends of the
toggle links 25, 26, the former of which rests at H
its lower and outer end upon a block 2‘|_ supported '
on a fixed part 28; and the latter of which carries
toggle links when the mechanism is in the
Fig. III position.
Such mechanism produced a sieve motion rep
on its upper and outer end the cross bar 24 of the
15 cross head. The outer end of the upper link-26 resented by the graph Fig. IV where abscissae
is in the axial‘ line of the sieve and ‘the shaft 2|. ‘ represent ‘time and ordinates represent sieve ve
By means of the screw 29 which shifts the block locity.‘ The point A of the graph corresponds with
21 horizontally, the outer end of the lower link the commencement. of the downward stroke and
can be adjusted to be in the same axial line as .. point B. lies at about six-tenths of that stroke.
20 shown or to the left of said axis. A rod 30 ex ‘ The straight portion of the line approaching point 20
tending upward from the cross head engages a
guide 3| to counteract the side thrust of the
Bindicates'substantially constant increase ofve
locity, whilst the sharp peak at B shows the sud
den retardation. The steepness of the line from
The inner ends of ‘the toggle links‘ engage a B to C exhibits the rapid reversal to upward
pitman 32 which is reciprocated endwise by an movement and compares with the slower‘reversal
eccentric 33 on the shaft 34. The pitman lies ' at the top of the strokershown by the less steep
, 1
approximately 'at an angle of ninety degrees to line C. A. B.‘
By shifting the block 21 over to the left, the
the toggle but the shaft bearings 35 are adjust
able vertically on their ?xed support, toienable length of the sieve stroke is increased and the efé
30 such angle to be varied. The shaft‘is rotated as fects mentioned above in reference to the graph 30
by abelt pulley 35 and is ?tted with a‘fiy-fwheel ‘ are intensi?ed.
The pulp to be treated is delivered by a‘pipe
31 vfor maintaining regularity: of rotation." Con
43 into a stationary annular hopper 44 surround
tact between the bar 24 and the toggle is main
tained by'springs 38 compressed between a ?xed ing the shaft 2|. Said feed pipe delivers the
35 member 39 and the cross-arm 4|! on the shaft 2|. pulp tangentially into the hopper‘so that 'it is
The tension spring“, the’compressionsprings well distributed all around the same. The hop
38 and the reciprocating parts‘renresented main: per has a bottom discharge in the form of a short
pipe 45 which’ directsthe pulp into, anannular
ly by the sieve, “form a system adapted for verti
cal oscillation with a natural frequency: and when
40 forcibly displaced from its neutral ‘position and
released. would continue'to oscillateuntil stopped
by friction." The headfrnotion therefore'has mere
ly to maintain the reciprocation by making“ up
friction lossesand is not called upon tofsustain
45 the weight of the sieve." It has'only to govern
the accelerations and’ decelerations ‘of the sieve
and not to provide thelwhole ‘of the force neces:
sary for each such operation.’ . The natural fre
quency of reciprocation of the systemldepends
principally'ron the mass of the loadedh‘sieve and
the upward and downward pressure of the re
spective springs. By making the spring pressures
su?iciently great relatively to the mass, the nat
ural frequency of thersystemr may‘v be made as
55 high as desired; that is,’ rapid reciprocation, of
the sieve may be attained without unduly stress
ing the head motion._ Such rapidrreciprocation
permits of a large number of short strokesr'per
unit of time; so giving ahigh throughput, and
60 also ensuring that the bed is left open or in sus
pension 'when the upward stroke of the'sieve be
gins. The tension spring'4l has an adjustment
42 to compensate for varying‘ weight of the bed
The arrangement is such that the toggle oscil
lates between the-broken position of Fig; I and
the Fig. III position in which the links are more
nearly alined' with one another. The result is
that the sieve is‘ reciprocated vertically between
70 its lowered position of Fig. I and. its raised posi
tion of Fig. III, with a motion which is character
ized by "substantially constant downward accel
eration approaching a point more than half the
downward stroke, sudden retardation, and‘ rapid
75 reversal to upward motion;
The machine'has
receiving trough 46'on the sieve.
> '
Water is supplied to the hutch from an open 40
tank 41 in‘ which'a predetermined water level is
maintained as by a ball valve 48.‘ Such level
may be varied by adjusting the ball up or down
the threaded spindle 49. -A pipe 50 leads from
the tank to a point in the'hutch' where the cross
section is large so that the in?ow does not in
terfere with’the settlement of the concentrates;
being provided with a conical'cover 5| to prevent
concentrates from falling into it from the sieve.
-A non-return valve 52 in the pipe line prevents
water being returned from the hutch to the cis
tern by the pulsations of the sieve. The pipe 50
is of large diameter to' allow very free movement
of water from the tank to the hutch.
In the operation of the device, pulp for con
centration is fed from pipe 43' into the hopper
44 which feeds it evenly around the‘ annular
trough 46 of the sieve. ‘Owing to the vertical re
ciprocating movement of the sieve the pulp travels
readily towards the periphery of the sieve. The 60
concentrate passes through the bed into’ the
‘hutch; Whilst the tailing ?ows over the lip |4 into
thetrough 4. The seal | 9 prevents the'tailing
from leaking into the hutch at this point. For
the recovery of ?ne concentrates such as that
from pyritic goldore, a sieve stroke of from M;
inch to 7% inch is desirable, with a frequency
of about 2'70 to 300 complete'reciprocations per
minute. -
The continued acceleration of the sieve during 70
the greaterpart of its downward movement and its
rapidrreversal keep the bed open for a consider
able proportion of each period, thus facilitating
movement of the concentrate through the bed and
minimizing felting of the bed under conditions of V15
short stroke and little hutch water. The quick 7 ‘sizes,
high proportion
and delivered
of very
a concentrate
?ne pyrite. containing
return tends to cause hutch water which has en
tered the bed to be rejected downwardly rather
than upwardly, thus diminishing consumption of
hutch water. Also the interstitial downward cur
rents which are laregly responsible for drawing
the ?ne grains of valuable mineral out of the
ragging into the hutch are set up before compact
ing of the ragging has jambed the grains and.
rendered them immovable.
The level of the water in the tank 41 is so
regulated as to check, to the desired extent, the
downward interstitial water currents in the bed;
such currents, if too intense, ‘tending to carry
gangue as well as concentrate into the hutch.
The ability to maintain a constant level in the
The pyrite entering the circuit with the tube
mill feed was 706 lbs. per hour. The amount
of jig concentrate produced was 1.35 tons per
hour containing 16% of pyrite, or an output of
432 lbs. of pyrite per hour, representing an ex
traction of 61.1%.
The solids in the pulp leaving the circuit con
tained 1.5% of pyrite; mostly ?ne enough to pass
a 200 mesh screen.
I claim:
1. In a jig, the combinationof a circular sieve,
an adjustable lip seated on the periphery of the
sieve and consisting of a ?at metal band pro
vided with lugs and clamped around the sieve
tank 41 and to adjust such level, together with
the prevention of leakage by the seal l9, permit
such regulation to be accurately effected.
by means of said lugs and yielding ?lling pieces
between the lugs.
A jig constructed as described with reference
to the drawing was arranged to recover pyrite
from West Witwatersrand ore. The jig was lo
cated in the tube mill circuit and treated the
whole of the tube mill discharge after elimination
providing a central circular pulp-receiving trough, 20
means for vertically reciprocating the sieve, a
therefrom of plus 1/2 inch pebbles.
The net sieve area was 45 square feet.
speed was 275 R. P. M. and the stroke % inch.
The ragging was iron slag from a faggot heating
furnace crushed and graded to pass a screen of
0.187 inch square opening and to remain on a
2. In a jig, the combination of a circular sieve
?xed annular feed hopper comprising an annu
lar body ‘and an angular mouth of less diam-‘
eter than the body positioned above the trough
so as to drop pulp into the latter, a tangential 25
pipe for passingv pulp into the body so as to pro
duce a swirling movement therein and means to
receive tailing discharging from the circumfer
ence of the sieve.
3. In a jig, the combination of a substantially
sieve of 0.034 by 0.281 inch rectangular opening.
horizontal, vertically reciprocable sieve carrying
The tonnage treated was 1450 tons of solids per
24 hours; or practically one ton per minute.
This tongage is equivalent to 32 tons per square
foot of sieve area, per 24 hours.
The total water entering the hutch was 800 lbs.
a mixture of material to be stratified thereen,
means for passing liquid upwardly through said
per minute, of which approximately 100 lbs. per
minute were discharged with the concentrates
and the remaining 700 lbs. passed through the
40 jig bed. This is ‘700 lbs. of bed water per ton
treated, or 15.5 lbs. per square foot of sieve per
minute, or 0.25 cubic feet per square foot of sieve
per minute.
The feed pulp coming to the jig contained 41%
45 moisture, and the tailings pulp leaving the jig
contained only 51.2% moisture. The concentrate
screen, and a head motion therefor comprising a
rotating shaft, a pitman connected to the shaft "
for endwise reciprocation, a toggle disposed sub
stantially transversely to said pitman and actu
ated thereby, said toggle comprising two links
extending from opposite sides of the pitman,
one of said links resting at its lower end on a =1
stationary part and the outer end of the other
link effecting the reciprocation of the sieve.
4. An apparatus as claimed in claim 3 char
acterized by the provision of means for adjust
ing said shaft in a direction about at right an
gles with the length of the pitman.
5. An apparatus as claimed in claim 3, char
was discharged from the hutch at a dilution of _ acterized by the provision of means for adjust
2.22 lbs of water to each pound of solids (or 69%
moisture in the pulp).
The grading analyses of the feed to the jig and
of the clean pyrite separated (by means of hand
panning) from the jig concentrate were as fol
ing said shaft in a direction about at right an-'
gles with the length of the pitman. and means 50
for adjusting the ?rst mentioned link in a di
rection about parallel with the length of the
6. The process of concentrating ore and like
granular material consisting in forming a jig
Clean pyrite
Mesh Tyler
from jig con
centrate per
cent weight
—}é”+1/€" ______________________________ __
bed with said material in a body of liquid, re
ciprocating the bed in said body of liquid and in
each reciprocation moving said bed downward
with a close approximation to constant accelera
tion from rest to a point beyond the mid-period
of the downstroke stroke, at which it attains its
maximum velocity, then suddenly retarding it
and. reversing it into the upstroke so that it
attains its maximum velocity at less than half
the period of the upstroke,-and then moving it 65
with deceleration to the top of its stroke, the
It will be noted that the jig successfully dealt
with pulp containing particles of widely di?ering
movement in each reciprocation being purely ver~
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