Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~3~ 7~3
The invention relates to an apparatus
Eor separating mix-tures of solids, in particular
mixtures of minerals, into at least -three pro-
ducts of different specific gravlty by means
of a single dense medium of substantially unvaried
derl.sity, comprising a hollow body divided into
at least one pair of communica-ting consecutive
challlbers, each prov:Lded with tangential and
a~ L condutis arranged to allow the introduction
l~ and discharge of the produc-ts concerned, charac-
terised in tha-t of said pair of chambers one
is substantially conical and the o-ther is sub-
stan-tially cylindrical.
Applicants Canadian Pa-tent Number 1,117,903 issued
February ~, 1982 describes an apparatus for separating mixtures
of solids of different specific gravi-ty, in particular minerals,
comprising a pair of cylindrical chambers in series, into each
of which a different density aqueous suspension, defined
as -the dense separation medium, is fed in order -to produce
2~ a final separa-tion of the fed mixture into three differen-t
products.
'rhe dense medium is known to be generally consti-tuted
by all aqueous suspension of a finely ground m:i.neral, such
AS magllet:ite, or an alloy, such as Eerrosilicon, able to pro-
duce the required separa-tion in a cen-trifugal field.
The presen-t invention produces the sharp separation
oE a mixture of -the aforesaid type into at least three
d:i.E:Eerent products of dif:Eerent specific gravity by using
an apparatus for separa-tion in a centrifugal field which is
3~ ab.Le to operate with a s:ingle dense separa-tion medium wi-thou-t
the need to vary the densi.ty oE this la-t-ter. In o-ther words,
a s:ingle dense medium of unvaried density is -to be used ins-tead
of two different densi-ti-tes as provided by the aforesaid paten-t
apE~li.cation in orde:r -to obtain separation into three products.
93
The fact of operating with a single dense medium of
~nvaried density provides the obvious advan-tage of eonsider-
able l~lant simpliEication with eorrespondiny redueed invest-
rnent and operating eosts, in comparison witrh the plant provided
by the known art involving two dense feed media of different
derlsities.
'I'he present invention again reduees the total quan-tity
oE derl.c~e med:ium necessary for separ.ation eompared with the known
art, so as to ~e able to attain a further reduction in operating
:L0 costs, thus saving energy.
The invention also attains a sharper and more precise
separation of the final products.
Aeeording to the invention there is provided apparatus
for separating mixtures of solids, in particular mix-tures of
minerals, into at least -three produc-ts of differen-t specifie
gravity by means of a single dense medium of substantially
unvaried denstity, eomprising a hollow body divided into at
least one pair of eommunieating eonsecutive chambers, each
p.rov:ided with tangential and axial conduits arranged to allow
the :introduetiorl and diseharge of the products eoncerlled, oE
sai.d pair o.~ chambers one being substantially eonical and the
otller substant:ial.ly eylindrieal.
~ ceordi.ng to the present invention therefore there is
prov.lcled an auparatus for separating mixtures o.E solicls of
d.i.:E.Ee:l-ent speciE.ic gravity :i.nto at least three products of
di.E.rererlt spee:i.f:ie gravity by utilizing a single dense mediurn of
sl.lbstallt.i.ally unvaried density, eornprising: a body portion; a
part:it:ion wall dividing said hollow body into two eonseeutive
:E.irst and seeond chambers of substantially conical ancl cylin-
3() d:r:i.cal configurations respectively; wherein-the first, concical,
ehamber na:rrows i.n a dire~etion away from said partit:ion wall and
te:rm:lnates in a high density produet diseharge opening and the
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second, at least substantially cyllndrlcal chamber has a low den-
slty product dlscharge openlng at an axlal posltlon remote from
sald partltlon wall and there Is further provlded an Intermedlate
densl-ty product dlscharge opening for the second cyllndrlcal
chamber cllsposed between the partltlon wall and the low denslty
product dlscharge openlng; means deflning an openlng For conduct-
lng an admlxture through the partltlon wall from the flrst, conl-
cal chamber Into the second, cylIndrical chamber; means for
Introduclng uncler pressure Into the fIrst, conlcal chamber an
admlxture of sollds of cllfferent speclflc gravlty and a slngle
dense medlum anc. effectlng separatlon thereof Into a hlgh densl-ty
product/dense medlum admlxture whlch dlscharges from the flrst
conlcal chamber through sald hlgh denslty product dlscharge open-
lng, and a lower denslty product/dense medlum admlxture whlch
dlscharges from sald first conIcal chamber through the admlxture
conductlng opening and Is thereby Introduced Into the second,
cyllndrlcal chamber; means for Introduclng an addltlonal amount
of sald slngle dense medlum Into the second, cyllndrlcal chamber
whereby to effect further separatlon of the reduced denslty pro-
duct/dense medlum admlxture Into an intermedlate denslty pro-
duct/dense medlum admlxture and a low denslty product/dense
medlum admlxture dlscharges from the second, cyllndrlcal chamber
through the low densl~y product dlscharge openlng and the Inter-
medlate denslty product/dense medlum admlxture and whereln the
2S low denslty product/dense medlum admlxture dlscharges from the
second cyllndrlcal chamber through the Intermedla-te denslty
procluct dlscharge openlng, thereby obtalnlng three products of
dlfferen-t specl-flc gravlty. Sultably the admlxture Introduclng
means Is posltloned adJacent the par-tltlon wall. Preferably the
Intermedlate denslty product dlscharge openlng Is posltloned
aclJacent sald partltlon wall. Deslrably the conlcal and cylln-
drlcal chan1bers are coaxlally arranged.
In one embodIment of the presen-t Inventlon the centre
llne axes of the conlcal and cylIndrlcal chambers are offset.
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~236~3
Desirably said admixture conducting opening comprises a curved
passage between the concial and cylindrical chambers.
In anotller embodiment of the present invention the
cylindrical chamber is defined by a peripheral wall which is
slightly frusto-concial in configura-tion narrowing in a direc-
tion toward said partition wall. Suitably the admixture intro-
ducing means and the intermediate density product dis~harge
open:ings are disposed with axes -thereof -tangential to the coni-
cal and cylindrical chambers, respectively. Deslrably the ad-
m:ixture introducing means and the intermediate density productdischarge openings are each part of a volute. Preferably -the
rnaterial conducting opening and the low density product dis-
charge opening each include a short pipe.
In another embodimen-t of the present invention the
apparatus further includes a cylindrical chamber immediately
adjacent saicl second, cylindrical chamber and an end wall of the
lat-ter forming a second partition wall between the two
substantially cylindrical chambers, the low density product
discharge opening providing a means for conducting an admix-ture
through the second partition wall from the second, cylindrical
chamber into said further cylindrical chamber, said further
cyl:ind:rical chamber having an axial discharge opening for a
product having a lowest density, said opening being at a
position remote f:rom the second partition wall, and a Eurther
cl:ischarge opening Eor a lesser density product from said further
cy:L:i.rlcl.rica:l chamber disposed between the second partition wall
ar)d sa:id :lowest density product discharge opening, means for
introduc:irlg a still further arnount of said single dense rnedium
Lnto the further cylindrical chamber whereby to ef:Eect further
30 sepa:rat:ion of said low density product/dense-medium admixture
:into a :Lesser density product/dense medium admixture and a
lowest density product/dense mediurn admixture; said lowest
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~ ;~3679;:~
density product/dense medium admixture discharging from said
further cylindrical chamber through the lowest density product
discharge opening; and -~he lesser density product/dense medium
admixture discharging from said further cylindrical chamber
through the lesser density product discharge opening, whereby an
additional product separation of yet different specific gravity
is ef~ected by utilizing -the single dense medium.
Within the basic concept of the inven-tion, i.e. of
assoc:iating a conical chamber with a cylindrical chamber in
1~ serLes, it is possible in prac-tice to provide various embodi
rnents of this apparatus, all with -this basic characteristic.
The characterictics and advantages of the invention
and of its various embodiments will be more apparent frorn the
description given hereinafter of -these embodiments with ref-
erence to the Figures of the accompanying drawings.
These embodiments are in no way to be considered as
limitative of the invention and merely illustrate various pos-
sible cons-tructional forms.
Figure 1 is an axial longitudinal section -through the
apparatuS;
3()
B
36~
~i~ure 2 is a cross-section on the line II-II of ~;gure 1.
~i~ur~ 3 ~ a vie~ analogous to that of ~igure 2 but illustrating
a modified embodialent.
~i6ures 4, 5, and 6 are vieus analogous to that of Figure 1 but
S illustrating a further three embodiments.
Uith refercnce to ~igure 1, an apparatus accordill~ to the invention
is constitut,ed by a hollow body 1 divided by ~ transversc ~all 2
into a pair of consecutive chambers 3 and 4, vf ~hich the first
is of subst~ntially conical ~orm ~ith a cylindrical portion in
proY~imity to the ~all 2, and the second is entirely of cylindrical
form, Thc t~o chambers eom~unicatc by ~ay of a tubular conduit
5 disposed in the ~all 2 along the axis o, the bo~y 1.
The ancx of the conical cham~er 3, positioned opposite the ~all
2, is open at f~, whereas at the other end of the body of the apparatus
the end of the cylindrical cham~er 4 is provided uith a front ~all
7 in ~hich an a~ial conduit 8 is disposed.
In ~roximity to the transverse ~all 2, both eha~bers are provided
with a t~ngentially mounted conduit; namely ~he ch~ber 3 with
the ~onduit 9 and the ehamber 4 with the conduit 10~ These eonduits
can be either eylindrical pipes which are tan~entially inserted
into the body 1 as shown in Figure 2, or pipes which are connected
to the ~all of the body 1 by means ~f a volute 2s shown in Fi~ure 3.
An analogous conduit 11 is mounted on the body 1 in proximity to
the frollt ~all 7.
The mixture o~ solids to be separated, to~etller with the dense
separa~ion medium, is fed through the conduit ~ into the ehamber
3 at a suitable pressure, uhieh is obtained for example by ~eans
93
of a charging vessel or a pump. High-density separation occurs
in this chamber~ For exc~nple if the dense medium has a density
of 2.6 g/crn , the separation which can be att~ined in the conical
ch~nber will be at a density of 2.9-3 gJcm according to the rates
at which the output flows are regulated, and the type and particle
si~e ~istribution oE the dense medium used. Thus a higher
~Icnsity product leaves the apex 6 of the chamber 3, while a lower
density product is also separated in said ch~mber and flows in the
axial direc~ion toward~ the chamber 4, into which it penetrates
through the conduit 5 together with part of the dense mediurll.
~urther dense mediwn is fed through the conduit 11 and into the
chamber 4, so as to induce the separztion in this latter of a
first product of higher density thzn that of the mixture fed through
5; said product being discharged through the conduit 10, and a
second product of lower density9 which is discharged through the
conduit 8.
Thus the apparatus of Figure 1 separates a mixture into three
produ~ts, n~nely a product of higher density, a product of inter-
~ediate density and a product oE lo~er density.
If separation into four products is re~uired, accordin~ to the
lnvention the apparatus shown in Fi~ure ~ is suitable, this
differing from that of Figure 1 by the presence of a third chamber
12, oE cyl~ndrical form, provided with a pair of tangential conduits
13 and 1~ and an axial discharge conduit 15 mounted in a front
wall 16. In this case, the product of lower density which emerges
~rom the discharge conduit 8 of the chamber 4 acts as the feed
to the chamber 12 in which further separation takes place into a
93
,~
product of higher densi~y which leaves through the discharge conduit
13, and a prnduct oE lower density ~hich i9 discharged through
the con~uit 15, Thus four products are obtained fro~ the discharge
conduits 6, lO, 13 and 15, and consist of fractions of the Eeed
throu~h 9, in decreasing order of density.
The apparatus of Figure 4 can also be advantageously used for the
prot1uction of only three 1~roducts by combining the dischar~d
products -Erorn lO and 13 into a single product. In this caseJ the
separation carried out in 12 represents an irnprovemerlt of that
carriec~ out in 4, ie able to recover t1-1ose fractLons of heaYy
mineral which, in an apparatus comprising oniy two chamb~r~9 ~1ould
be entrained into the axial discharge stream and lost with any
tailings.
The arrangement of the apparatus during operation can be as sho~m
in Figures l and 2, ie with the lon~itudir~l axis disposed hori70nt-
ally, or alternatively ~ith the a~is inclined either with the
apex of the conical charnber pointing upwards or w;th it pointing
downwards, according to the speciEic separatior. req~?~rements.
A modification of the inv~ntion is shown in Figure 5, in which the
hollow bod~ l is of V configuration, with a conLcal charnber 3
communicat;ng with a cylindrical chan1ber ~ by way of a passage
conduit 5 provided in an aneular connection piece 17~ of ~Jhich
the length and curvature are predetermined in order to lirnit
pressure drop of the vortex flow as it passes f~om one cha~nbe~
to the other throush the conduit 5. This modiEication ~as the
advantage oE Eacilitating dischargc of the separated products
fronl 6 and 8.
~3
_b
~urther modificatlons uith respect to the apparatus of FiEure 5
and to the apparatus of ~igur~ l uhen of inclined l~n~itudinal
axis can be attained by reversing the posieionS of the conduit ll
for feedin~ dense medium into the cylindrical chamber and the
discharge conduit lO for product of intermediate density ~ith
respect to the positions shown in said figures, ie by ~ountine
thc conduit ~or feedin~ dense medium into the ch~nber in
proximity to the trans~erse wall 2 (or an~ular connection ~iecc
17), and mounting the tan~ential product outlet conduit in
1~ proximity to the front uall 7.
A further modific?.tion ~f the invelltion ~s c~o~n b, ~ay Or e,zm?~2
in Figure 6, in ~hich the chamber 4 sli~..ly tapers toh~ards Che
centre of the apparatus~ ~his slight c~icity c~n facilitate
the discharge of the ~roduct (in the case of t~o-chamber ~np~rz~us) or
of the products (in the c~sc of t~rce-chamber apparatus) ~rcm the
tangential outlets of the thus tapered cylindrical chamber, ir-
that the t2ngential velocity inside the scparators increases
between the zones of ~reater diametcr (~here the dense medium is
fed) and th~ zones of smaller diamet~r ~ere the tan~ential
discharge is located), due to the lau of momer;tum consorvation
in vortex motion fluidJ. rGnsequently, and ir. particular ~hen
a cons1derable ~uantity o~ product is to be discharged tan6~nti211y,
this arranGement can r~sult in improved operatio~ of the apparatus.
.. .. . .. .. . . . .. . ... _ . . . . .. .
~;~36~33
l~n ~ he afore~;oinr examples~ S)-e dischar~;e
port provided at the apex of the conical ch~mber can be of adjustable
diameter. Tl,e tan~ential discharge co~uits for the intermediate
density prc~ucts fror~ the cylindrical chambers can be adjustable
5 both ~ terms of diameter and in terrDs of the back-pressure applied
to them for the correct operation of the apparatus.
FroTn thc afore~oinG descri~tion, it is alJparent that thc invention
effectively attains the stat~d objects.
Firstly, it is possible to use a single dense medium of substantially
1~ unvaried dcnsity. The m~in reason ~or this is that the density
at which scpzratioll occurs in the conical chamber is higher than
that of the dense medium fed, ~hereas in the cylindrical charnber
~t is approximatelY equal to that of the dcnse mcdi~.
~oreover, because the conical ch~ber requircs a volume of dense
15 medi~D which is less th~n that of the ~ylindrical chamb~r, the
total qUalltity of dense medium necessary is less than in the kno~n
- art.
}urtherrnore, ~he separation accGrdinG to thc invention can be more
p~ecise, especially uhen the cylindrical cyclorle ~hich normally
20 constitutcs the first stace eives a high proportion of finished
pr~duct, so that the residual ~raction to be separated in the
second sta~e is reduced, ~ith conscquent SCparatiGn improvement.
The apparatus of the invention can also be used with dense rnedia
of diffelent densities.
