Modern Solutions to Screen·ng Problems

Mogensen Sizer

Mogensen Divergator

Tvvo principles The Mogensen Sizer ls used for separatlons at polnts between Ο. Ι and 50 mm and the Mogensen Dlνergator at 25 mm and upwards; the coarsest separatlon so far ls at about 400 mm. Both prlnclples alm at glνing efficient separatlons with small and slmple equlpment wlthout blindlng. fhe slzer and the dlνergator are protected by seνeral patents and patent appl lcations.

The Mogensen Sizer The 8izer work8 wιth 8eνeral 8creen cloths mounted one aboνe the other ιn a νιbratιng frame. The aperture8 of the 8creen cloths are larger than the maJorιty of the particle8 that arriνe at them ln 8pιte of thιs sιze difference, 80me pre-separation occur8 eνen at the top deck, where the dι8parlty be­tween aperture size and aνerage

partιcle 8ιze ιs at ιts greatest the fιne8t partιcles pa8s through im­medιately wherea8 the coarser ones bounce further down the deck and may eνen leaνe the 8izer at this ροιnι. More and more partιcles will be brought out of the sιzer by the followιng decks according to their sιze or ιnabιlity to pass the me8hes By a suιtable selectιon of screen cloths, νibratίon, and 81opo the p3r-

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tιcle 8ιze range ιn the products can be ιnfluenced Τhι8 allow8 great operatlonal Flexibility · e.g. the prod­ucts can be altered slmply by chang­ιng the slope of the sιzer

The Mogensen Divergator The dινergator con8ι8t8 of a number of bars parallel to the flow of mate­rιal They are mounted alternately ιn two differently slopιng plane8, wιth the result that the dι8tence between adjacent bar8 ιncrea8e8 ιn the dι­rectιon of the flow-the bar8 dι­

νerge, and 88 the lower end8 of the bar8 are free the dινergator wιll not blind lt requιres no cleaning and maintaιns its good separating abilιty. The dινergator ί8 8tatlc end simple to ιnstell , cheep ιn operetιon and serνιco.

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Fredήk Mogensen, Dr.Eng.: Ι haνe often been asked : 'Ήοw dld the ldea of maklng separations at • glνen size by using much larger meshes come to you?"

Α comparison Difference in function The Mogensen Sizer The flgure shows schematically part of a sιzer ιn sιde νιew. Most per­tιcle8 are smaller than the me8he8 they arriνe at so that no obstructινe and ebrading bed8 of meterιal are created the partιcle8 moνe freely, and ιndινιdually rapιdly through the aιzer Τhι8 gινe8 the 8izer e νery hιgh cepecιty and an indiνιdua l ιreat­

ment of each partιcle The lerge me8hes do not bl lnd eνen with seν­erel moi8t and stιcky material8 whιch ere otherwl8e often ιmpos­aible to screen The rete of wear ι8 low becau8e partιcles ere deelt with

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• ο ο

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ln my laboratory we had been ιn­

νestιgatιng For some tιme the ιn­

fluence of the bed of materlal ιn conνentιonal screentng. Bearlng tn mιnd those problems wh ch ο bed creates : excessινe weer. low capa­cιty and bllndιng, it was not surprιs­ιng that one arrινed at the questιon : "ls thι8 bed necessary? Wouldn't it be pos8ιble to abandon these rather

Mogensen Sizer- conventional screen by decks appropriate to theιr sιze· the largest partιcles neνer reach the lowest, fιner decks.

Conventional Screen The figure shows the conνentlonal solution of the same screenιng prob­lem as aboνe same partιcles and same separatlon Α large proportion of the partιcles is bιgger than the meshes; seνeral particles are about the same size. The particles form a bed whιch hinders theιr anempts to pass the screen cloth. The particles close to the size of the aperture get stuck. Coarse partιcles dιsturb the process. damage the relatινely fine screen cloths and cause atrition of the finer partιcles .

.. . . ' , :-.· .. · . . .• . . .. ·.: . ,. ..

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•• •• • • •· . . . . . ••• . . . .. • . .. '.' . . . . ' • • ·. • • •

anc ent ιdeas behlnd conνentl onal

screen ng and work wιthout the bed of materιal ι e haνe materιal flow­ιng freely through a space contaιn­ιng relatινely coarse meshes?" The ιdea may be traced ιn my doctor's thes s from 1941 \1-Je bu lt a smal l ιηodel ιn wood about 2 χ 1 dm (8 χ 4") the fιrst

Mogensen Sιzer lt worked and was

Difference in capacity The diagram shows the relation be­tween specific capacity expressed ιn t/h per sq m. horizontal surface in relatιon to the separation in mm with materlals of the bulk density 1.6 t/cu m (100 lb/cu ft ). The dots represent νalues obtained with the Mogensen Sιzer The empty, slopιng surface undemeath coνers the com­mon capacιty formulaes for conνen­tional screens.

The sιzer has a specιfic capacity whιch ιs 5--20 tιmes hιgher This makes the sιzer an efficient and economιc solutιon to screening problems lt is light, sιmple to ιnstall, has little energy demand and re­quires no compllcated serνicing.

SPECIFIC CAPACITY t/ h-m2

1000~-4-~++4+~--~~44~~~-~=+~~~

5 -+-- -+-+--'

0,1 0.5

the begιnnιng of a fascιnatιng de­νelopment.

The dιvergator came later and was ln the begιnnιng intended to be a selfcleanιng pre-separator for the sιzer. Howeνer. very often one or more diνergators offer νery attrac­tινe solutιons to νarιous screenιng problems

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5 10 50 100 SEPARAτJON mm

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Three types of Mogensen Sizers DESTOR Data : We1ght lnner w1dth Gross dimensΙons

Mode of actiνatιon

AppllcatJon :

ca 900 kg 975mm length ca 1 7 m width ca 1 2m height ca 2.2 m 2 ν1brator motors each 1.1 or 1 5 kW

The DESTOR is used for h1gh feed rates and ΙS often coupled w1th a d1νergator

DESIBI Data : Welght lnner wldth Gross dΙmensΙons

Mode of actΙνatΙon

Appllcatlon :

ca 470 kg SOOmm length ca 1 .9 m width ca 0.8 m helght ca 2.0 m 2 νlbrator motors each 1.8 kW

The DESIBI ΙS used for wet siz1ng and for separatΙons at 1-50 mm

Accessories for special problems Dust Α8 the 8Ιzer Ι8 a small machΙne. it Ι8 s1mple to enclose, e.g 1n a dust proof box. We al8o 8upply dust tight enclosure8 which are adapted to our slzers, e g for the DESIBI and the DESIO there are attached en­closure 8y8tem8

Wear The sizer can be fιtted wιth a rubber llnlng or wlth replaceable staιnless steel plate8 on surface8 wh1ch come

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1nto dlrect contact with the materιa l

Rubber ιa normally used for moιst and cold matensls, whereas steel plstes are more common for hot msterιsls .

H'eat When treatιng hot materιsls. e.g sιnter st 600°C, the temperature can become too hlgh for common vιbra­tor motors. ln such cases the vibra­tor motors can be replaced by an

DESIO Data: We1ght ca 310 kg lnner width 500 mm Gross dιmensΙons : length ca 1 7 m

w1dth ca 0.8 m he1ght ca 1 9 m

Mode of actΙνatΙon 2 ν1brator motors each 1.2 kW

Appllcatlon : The DESIO ΙS used for finer separa­tΙons of materΙal Q.-20 mm

excιtor unit whιch ιs driνen ν1a a cardan shsft by a motor posιtioned

outaιde the hot zone ln less extreme case8 ν1brator

motor8 wιth specιal ιnsulatιon can be used.

Moisture Moιst material8 can cause bllndιng

through sticking. especielly at fιner 8θpsratΙOΠ8. Α8 the 8izer uses screen cloth8 wιth cosrser than

The Mogensen Divergator

Data : The dινergator is specially made for each screenlng problem. lts wιdth can normally be adapted to exιstlng systems whereas the dιameter. the length and the 81ope of the bars are determιned by the material to be treated and the desired separatlon. The diνergator i8 normally 8tatιc, i e. consumes no power

Application : The diνergator 18 used for separa­tton8 at 25 mm and coarser lt can be ιn8talled a8 a 8ingle unit. in se­rie8 or in comblnation wιth the DES­TOR See pages 6 and 7

normal apertures, it ιs less sensιtiνe to blindlng than conνentional screen8. Further, the 8creen cloth8 of the 8izer are relatiνely small in area and thus easy to heat electri­cally to preνent the moist material from stιcking to the wires. We sup­ply equlpment for heatιng the screen cloth8. Some materιals are 80 dιfficult to treat when ordinarily moist that they must be dried, further wetted or eνen sluπied

Advantages Versatile

• Separations between 0.1 and 500 mm (150 mesh-20").

• Capacity up to 800 t/h per unίt.

• Copes wίth dry and wet materίals, also sluπίes.

• Superior with moist and stlcky materials.

• Copes with hot mateήals up to 800°C.

• Suits dίfferent partίcle shapes.

• Copes with seνeral "impossible" materίals.

Technically attractive

• Ν ο blίndίng : constant separation.

• Simple to dust enclose.

• Simple to protect against wear.

• Coarser screen cloths with longer life and near constant separatίon.

• Small units-high capacity.

• Low weίght : low power consumption.

• Simple installation : low transmίtted νibration.

Economically advantageous

• Small in relation to ίts capacity : economy of space, lower power consumption, cheaper installation.

• Simple construction : reliability in operation, cheap serνice-e.g. change of a screen cloth can be made in about 1 Ο minutes.

• Coarser screen cloths : longer life, no cleaning costs.

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Applications Crushed rock 0-400 mm, 300 t/h Stθtens Vagνerk ι . e . The Nθtιonal Swedish Road Administrθtion ob­tθ ιned during 1972 two two-stage crushιng plants for the production of 0-4, 4-25, 2~75, θnd 7~200 mm. ln order to mθke full use of the hιgh capacity of the primary crusher, θ diνergator is instθlled immediately before the secondary crusher so thθt only materιal oνer 200 mm is crushed. (see drawιng θnd photo­grθph) Besides the ιncreθsed capa­city, the wear of the crusher is re­duced. The bθrs of the diνergθtors lθst θbout 50,000 tons, correspond­ιng to a cost of less thθn Ο 1 p/t.

0-25 mm, 80 t/ h For the separθtlon θt 4 mm, θ sιzer tyρe DESIBI is used. lt ιs mounted ιn a transportable frame together wιth θ νi brθting feeder whιch giνes a ρeήect feeding, (see photograph). The sizer makes a νery shθrp sepθ­ration at 4 mm wιth recoνeries of oνer 90%. (see diagram).

Fish meal 0-100 mm, 6-8 t/h

Hull Fish Meal & Οιl Co Ltd in England has three sizera type DESTOR. The fish meθl dust is explosiνe and the sizers are en­closed, (see photograph) The fish meal is sometimes νery oιly and sticky sometιmes easy to treat θnd the sizers produce up to 850 tons during a 70-hour week. The coarse product oνer 1 4 mm is returned to grinders whιch pro­duced 2 4 t/h before the sizers were ιnstalled Today the corresρonding fιgure is 3.7 t/h θn increase of

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nearly 60% The cost for grιnder serνicιng has gone down from Ε36Ο to Ε120 per month Thιs saνιng ιs

the result of reducing the number of work hours and of reducιng the νolume of materιθl recycled as a result of the more efflcient sepθra­tιon .

The saνιngs in serνicιng costs of the sizers as compared wi th the preνιously used conνentional screens, are considerθble Νο

meshes were changed durιng the fιrst ιhree years.

Limestone slurry 34-36% Η20, 0---2 mm, 70 t/h reap. 175 t/h

ΑΒ Cementa, Lιmhamn ιn Sweden has eιght sizers tyρe DESIBI for wet sizing, (see flow-sheet) The ιορ coνer picture shows six of them The four sizers to the Ιeft in the pιcture treat together 280 t/h with a separatιon at about 0.3 mm. The two to the right are fed wιth 350 t/h and separate at 1 mm. The

Moist clay 11-15% Η20, 0---2.5 mm, 8 t/h

Hoganas ΑΒ, Southern Sweden, has 8 sizers type DESIO ιn a facιory for ceramic wall tιles The screens pre­νιously used bl inded rapidly and needed contιnuous cleanιng The sizers are fιtted with electrical deck­heating and blιnding has been com pletely ellminated. The figure shows the ιnsta llatιon of 4 DESΙO Two work inside the dust tιght box. whιlst two are outslde. The sizers are suspended ιn four carriages on the same raιl so that exchanging and serνicing is easy Hoganas ΑΒ has bought more than 60 sizers for different purposes

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Sinter 300°C, 0-400 mm, 180 t/h

Brιtιsh Steel Corporatιon , Consett Works has a diνergator which sep­θretes at about 25 mm θnd a sιzer type DESTOR for the separatιon θt 4 mm. The bottom coνer picture θnd the drθwιng show the compact ln­stallation. The sιzer is fitted with replaceable weθr plθtes θnd the screen cloths lθst between 24 ,000--56,000 ton. The wear cost is θround 0.28 p/t whιch is θbout V3 of what θ preνι-

fιnes 0--1 mm goes to a mill after which two DESIBI in parallel re­moνe around 1 Ο kg/h of grιnd ing balls and other impurities. The sizers are equίpped wίth rubber lining--a small amount of flintstone makes the slurry abrasιν~nd haνe rub­ber enclosures

The dlagram shows how the feed and the two products are distributed in relatιon to the particle sιze. The coarse product Ιs 25% of the feed and the fine 75% The dlθgram also

ously lnstθlled screen cost. All the sinter to the blθst furnθces pθsses this sιzer system and the client ίntends to double it with θ

similθr, easy to exchange spθre

system. Both systems θre to be suspended ιn carriages to facilitate serνicing and reduce down-tιme. Β S.C. uses sizers also for iron ore. pellets and coke; for the Anchor­project ln Scunthorpe they haνe ln­stalled 21 DESTOR.

gινes the θpertures of the meshes used Note the difference between the finest mesh, 1 Ο mm, and the sepθrθtίon Ο 45 mm

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Materials The followlng llst shows some of the mateήals whlch haνe been successfully treated by Mogensen Sizers and Dlνergators :

Alumιna

Ammonium nιtrate (also prilled) Andesίte Anthracιte

Asbestos Ash

Basalt Bauxιte Bentonite Bone, cooked; crushed

Calcium ammonιum nitrate Carbide Carbon Caustic soda Cellulose powder Cement clιnker Ceramic materials Chalk Charcoal Chemιcals Chιcken food Chιna clay Cιtric acid Clay, (also expanded, granulated;

moιsl) Coal Coke (also breeze ; dust) Copra Coremanιte Cork Cyanite

Detergents Oiorιte

Dolomite

Eχp losiνes

Feather meal Feldspar Ferti lizers Fιsh food

Fιsh meal Flint, calcined

Garnierιte Glass-powder Glucose Gneiss Granιte

Grape sugar Graνel

Grog Gypsum (also burnt, raw; rock)

Hematite Hide glue Horn & hoof meal, crushed

lron ore lron powder lron sponge

Kιselguhr

Light weιght concrete Lignine sulphonate Lιgnιte

Lιme, burnt, slaked Limestone Lιmonite

Magnesιa burnt; fused Magnesite (also calcιned ; raw) Magnetite. (also pulp) Marble Matte Meat meal Melamine Mullite

ΝΡΚ

Oliνιn

Ore, chromιum , copper; iron Oχalιc acιd

Pellets Perlite Porphyrite Plastic, granulated Pulps Pumice Purple ore PVC powder Pyrite, (also cιnders)

Quartz Quartzιte

Reformer catalyst Resιn

Salts Sand (also drίed ; slurry) Sandstone Scheelite ore Schist (also flakes) Sepιolite Serpentine. agricultural Shale, (also burnt) Sinters Slags, {also granulated) Slate Slurries Soda ash Sodium metasιl icate

Soot Steel shot Sugar Superphosphate

Talcum τ etryl eχplosiνe Tobacco Tripolyphosphate

Urea

Vermιculite Welding powder

Zeolite

A#OGEJVSE~ )) Slzer cc -Kiasslertechnlk

Mogensen GmbH & Co KG, 2 Wedel / Hιmburg, Postt. 149, Pinneberger Str. 91 Tele1on (04103) 82025, Telex 02189542 mogsd