AU608378B2 - Sorting apparatus - Google Patents

Description

oC9 COMMONWEALTH OF AUSTRALIA PATENTfS ACTU952 COW-CU SICCATIQ NWE &ADDRESS OF APPLICANT: De ~er Irtutrla Dlamrond Divisiora (rprieary)LIted 0~ Main Street Johannesb~urg Trwisval, RoputtioQ of South Afrbit N1AIV($) OF TNVENTQR(S) 101niuanueuu~ 13OW Neville Br1iI rnt UAMMQNI) DAVID Auto 0 Q 0 4 0 0 ADDRE~SS FV9 $EJ3V' DAVIES CQWSON' Patevit Attorneys COMPLETE SPECWWIATIQN VOR Tt IN VIITh4ON ENTITLED: rte~ (folW~vlwIt tefient I's It full descriptionl Of tills juentlnt I lclditi (hc b"t Method 6( perforrnlog lt~ww to Mem.

THIZS ifvent oQ r010ae0 to a 00rtinq, apParat"s Most cofnvqntonal apPaZ1at~u Qse for sorti~n pt:ritittcato Mnate4 have a oonVoyQr belat whicoh causes the p&ticles to Move SLaeesS4vQ~y, usuay A n free fiCight, thrauci an excitation Zofle, A dotojo Ztiw and an ejection zone, To enable the appaatus to handle a lar, e throtghput the particle$ ar0 Arranged in a wia mono2aye on the belt, wih a nuMbr of particboe aezros! the width of the belt, 14 the excitation zone, th e particles may, ffo insatanee be puject to X-rtadiation in~ i case where diam~mds are to be sorted frQno gangC Downtrean of the exciation Zone is a detection zone where a series of photomulti&ter (PM) tube s are arranged across the width of t Jhe belt to detect luminosacene in the partiloeap Further downta hank air blast ctor,, is aaned Whn a ludmnes-iorgr porticlo is detected at the OetectioR zone, tha appropriate ejector is actuated to issue an air blast whiCh deflectc the relqvafnt particle out o~f the main strant.

To Onsure that aucuate detection and ejction takes place, It i csretial that each PM tube and cach eector cover a $mall area only of the width o~f the ft ailing qtreom of particles. It, for Instance, the area 'see&I by a M tube IM large, an "ejoct'l sjnal could be lissued when any one of A nqumber of partiloo "seen' by the PH tube Is lumnesoing.

y i f the ejector bitnste too I la r asi inron, stion umi nomo ig partihke could also be ejocted, .3, o ou 0D a 0 9I D 0 0w a 0001 0 0 00 0 With continuing research, the sizes of the ejectors have been decreased with the result that they are able these days to cover smaller areas than was hitherto possible, However the cost of snall PM tubes has proved to be prohibitive. The present invention seeks to provide a sorting apparatus which minintisop the use of PM tubes in the detection unit of the apparotsU4 The vention pro0vides a particulate material sorting apparatus comprisi.ng*: a) means for moving particl e$ o the materia.l I a stream in a direetion tsra so -to the width of the3 stronee b) a plurality of optioa fibres eaoh having a fli _qt and a socond ond, tho first onds o the fibr(e being Arranged 'to receive light emitted in di'Lfnt, narrow width zriej, of the strueai y pertio in the diffent, width Zonea" a mnEvabl moobor havinq 6 a aptuo thothrugh which r tors succogsiveIly with tho second onds of the fibre snd pasoes any light tranismitted by' the 4ibro4 P9 the mtnber piovos d) a hL detectoro which dotoots light passd by the aperture lrspoative of the p JsitioiR of the 6perture: and 0) pioanear rosi ensivo to the light etocQtor and tho J)OEiition of the aperture When, tho e teetetr d oeotq tight to de ermi the wIdt;h zono of the stroom fromw wh01 the liuht wati (Amftted, 3S Th6 movnblo membor wo f be in tho, form of a- rotntre e

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.4disc. Xn this case, the apparatus may include, a motorz for rotating the disc and processor means arranged to receive signals from the motor and from the light detector and to analyse such signals and to determine, on the basis thereof, which optica:l fibre transmitted the light and accordingly which width zone f the stream that light was emitted from. Also, the first ends of the optical fibres are aranged in a linear array extending acrss at least a part of the width of the stream and the seqond ends of the optical fibres are arranged in a cirdpler array adjacent the rotatable disc. There may be a single bundle of Optical fibres of which -the first ends are arranged in a linear array across, the full width of the stream and a single light detector for detecting light transmitted by any fibre In the bounloe, qdA snl fibre m-y be provlido for ah width zone of the stroom. Altarnatively, mvUltiple fibres may be provided for each width, ZOne, Filters m-ay by associated with the fibres to p ass light of difforent cQloours The i4veotion also provides a mthod of sorting particulate material into fractio 1 S, the method oMinrisngq the step; of conveying particles of the o C5 materinl itn a stream in a direction transverse to the width of the stream, using optical fbres to tronnmit lght omittd by porticle8 in diffeen t width zones of the stroaom to a light detector and proidin gMeans 3 nabling a doterqrMnation to o made as to the identity of an optical fibre which transvnittod. light detected b y the light deteotor,1d and rdingly the, identity of the width 0no Of thO stream from which the light was omi8tetd The inivention wIll now bo described In moro deta-il, by way of exaple only, wtth referenco to the accompanyinq draW~nln whiclih Illvurates in aopparotus U according to an (C 8"; embodiment of the i~nvention in diagrammatic fashion, the apparatus being intended for' use in sQrting diamonds from gangue.

0 Q 0 at 0*0 ~tk~4351.s~4 in the drawing, a wide stream of diamond And gangue particles 1Q is illustrated generally with the reference numeral 12, The stream 12 is conveyed on A belt or chute 36. Arranged just above the strzeam 12, within an enclosure 13. through whIch the belt or chute passes, is an array of side-by-side lenses 1.4 each designed to pass light emanating froma a small width zone of the stream, Preferably. -the widthi zone will1 be so small that it can be occupied by a single particle only.

Connocted to each lens is one Ond of an optical fibre I$.

Qptiqal fibre light guides may he provided to conneprct the lenses to the optical fibres The f ibros 3.8 are arranged into a bundle within a sheath 20 ovor the mnajority of their lengths, The bundle of fibres enters a box 22 in which is loatda single PM tube 24 connected to a pocessing unit 26, The sheath terminates upon entry oe the fibre bundle iinto the box and the fibres are then spread out with their freq ends equidistantly spaced in a circular qrray beneath, a 4iSO 2$ mounted on a central. shaft 30 driven by a motor 32, Te is hn n ccnticaperture 34 which, as the dise rotates, sucentv3y risters With the $rov end,, the fibres. The single PM tube 24 isn directed at the upper side, of the disc and is able to detect light paossing throuejh the aperture irrespective 0 the position of the aperture, The qefeation of the illustrated apparatilt' is (Is follows.

Immedately preceding Its entry into the encosure 11, the stream of particles has passed through theo excitation zone Where it is subjected to Incident radiation. D~iamnond Particles in the ,Atreamn ltumnesce as. a. resuiLt or thlin Qxcitation. The lght emitt by a !U4t nelcing p~trticle it- 6pick~ed up by the relevant lens 14, is then collimated by an appropriate collimator 15, and is transmitted by total internal reflection along the length of the asociated optical fibre 18, At its freeo end beneath the disce the light is released from the fibre and is transmitted through the aperture 34 when the aperture registers with that fibre* The transmitted light is detected by the PM tube 24 which send, an appropriate Signal tQ the prQqessing unit 26.

The processirW unit also receives information from the motor and is 41ble to determino, on receipt of A Signal fromt the PR tube A o the qxacVt position of the aperture 34 when the light wag~ detected. AhccorJdinqly, the processing uAnti able to determine which fibre 18 transmitted thel light and therefore which width zone of the tram 10 th jiht w -I emitted from, Thle proccossing unit then sends an actuating signal at thle Appopriate mnoment to tile appropriate one of a sicleby-sido array of air blast ejoctor5 (not shown) arranged alongs~ide the stream at a downstrearli position, Prefer'ably, each ejector will cover thle name widlth zone of th -I~a a-I ac lens 14 does, When the relevant ejector is actuated by thle si qra 1 it i'ssues a short dur'Ation blasIt of air whjichl delects particles in thle relevant widthl Zone out of thel( ~sbteagi 10 for oeparate colection.

qThe major adVa~aq of thle illus"'trlated apparatus in, the fact thlat there i~a requirement for only one PM4 tube While it is Otill poss"ible to determine In Which width Zone of the strem lumtnscnco took place. I n oneQ experimiental appartun Oontitructed by the Inventors-1, there wan, a total of twolty-ono len. is 14 and optic-al fibres 181 onch Ile-n u ocoveritiq a very vimll width zone only of tlie etreatM of i i -7particles.

it should be noted that it would be possible to have an even greater number of lneses and fibres, leading to greater accuracy in zone determintion, The fibres could, as in the illustrated case, be arranged in a single b: undle served by a single PM tub, Alternativel the fibres could be in diffterent bundles each served by a single PM tube, Fven in the latter event:, there will still be a relatively smal number of PM tubes only, In the illustrated asoe, the particles are tansported through the enclosure 11 on a conveyor belt 36, In other qapeo, the particles could be falling in free flight after ptojection from the ond of a conveyor belt. Note also that the invention is not limited in any way to any particular type of separator In the ejection zonev Instead of air bast ejectoro, the desired particles could, for in,,tance, be removed front the remainder of the stram by water blaot, or by suction Means, Note also that it is within the scope of the invention to use onQ or more PMi tubes for viewing fibres, which emanate from the samo width zone and whichi are each fed with a proportion of the ligjht emixtted by the particle. hi could be achieved, for instance, with the use of a mltl-way liqjilt splitter a-ssooiated With the lens 1l4 In thin ae"o it would be advanjtageous to use appropriate eltea eor eah fibre. P'or Instance, using the (s uitable filter, it Would be., possible to detect diamdntn whkoh luminesfce in the red part of the visible 8pectrutn And hence to separate thoese diamonds" from other patic'ef'..

-8 For security reasons, the optical fibres may be of considerable length, Thjis wotl enbeteprticles 10 to be viewed in a .security enclosuire and for the remaining operations be carried otat at~ an unseotired location, I I I

Claims (1)

1. 3. ApIatot1 a icztUnq to cli aonrn~ 11)(Ictot f tnj h Tfta 0tritcioo~ofn arncinld to rvoitvo djn t.oni a tho moo and thon tki liht, dot(tOc Ond to n atvyn Muh Si nahj (Ind to tIo~tiiitio, oi din WO Lhoteof, AIN Upital Ndtt ~tAuM 9OII2A~ ~ZI3S~p~ lighbt aind accorcfi~oy whioh width, Zoneo f the s1tzoLhthx 4" Aprp~~o icco -(Ungj to either ore Of K1oirn 2 r whevoin tho first ONcm of the opt4,&d fi.bres orc! ;lrrmu(Jc in i I ino r rri 09 t-,l (If 7 L V W( (,3i L1 i t( 21 I l. ~t Of ttho Width of tho staom (uinj tho £crd nsof the opt,~~ fibrotn 4zto ~a n~~vun d~u.t 1J Apzmihis icoding to cdaim 4 ia r~l hudeof opi'1 fillioai of whitc11 tho f 44 3t olvldu iovo arrio ill i) lio~t oy ir;tho full witth of fthe troytt~ed by any rituo in tho 1k indle, V Apparatun eAcoudincj to ony one) Or c~lffr to a Wilurein MultIP1e fihms rim ptovtd4u for vcwh width (ue ~hApp~iotarn~ octn1mdtng Lo otiy of theI ptimtnUH HnOW 0mgnou co'lourl ~otrtt an'UnIQI Yiac l th the opia imio for p wing light~ -t diffo~tW l 4uv 0. A; ~~tul sumdlUq to mny max ~Of the o mlvlb olcitma when mod h; nut di nun(I). frm n ciJUm4 I~ (),AMethod ot noti tig pMwtW 1Q1it t"Lin to franionqLim (IM" clpintlyj thepo tV of w~voyliq poattclun of the 01toat InO (I nutoan ti a dtrotton to tho With (if tho utlimm Unt fibmito tvtnundt Hol~t cilltted by' p lticlwl In~ f VONNp A/vIA a11 diffront width VOM~ Of the cstrean1l tCo ai 1iqhj detee 4nd proviing~ mioans ohnobin a cdteodain to lye Maidf r to the identi~ty of oni ctiec~l fihre hc nrte light (juc,tot~ by tho liq~ht (lot.QoZ'L, tinel t( t1 o h idcetity of tho Wfodth zn theo ft~oi which1 the IiQLt as~ Omiul demttit~tt, idu rubatowtioaly as heroin Anwibed with roforwvu to the SA inh~w of, riottitr, tt~flt Pwo omory (Inrtr0 uimw~ j INotoo UAV$I (t, 4 1iQ cj