particle separation

8/22/2019 Particle Separation

1/13

Gravity Separation of Particulate Solids in Turbulent Fluid Flow

Jrgen TomasOtto-von-Guericke-University Magdeburg, Mechanical Process Engineering, P.O.Box 4120, D -39106 Magdeburg, phone: +49 391 67 18783, fax: +49 391 67 11160,

e-mail: [email protected]

Abstract

The liberation of building rubble by comminution produces a predominantly mineral mixture with adensity distribution ofs = 1.8 - 2.7 g/cm

3. As a result of the relatively narrow density range, therequirements regarding the sharpness of the process employed for the separation of partially liber-ated aggregate and concrete-brick rubble are very high. For the gravity separation a test rig was

built consisting of zigzag channel, fan, air cyclone, filter and particle feeding system. Specific massflow rates 3 to 16 t/(m2h) related to apparatus cross-sectional area and mass related energy con-

sumption 0.2 to 8 kWh/t were obtained. To assessthe efficiency, the separation function is deter-mined and compared with a theoretical model of multistage turbulent cross-flow separation. On thebasis of the well-known separation sharpness as well as geometrical variability of a zigzag appara-tus, it could be shown that this separation principle is well suited for the gravity separation of min-eral materials.

Keywords: Cross-flow gravity separation model, separation efficiency, building rubble recycling

1 Introduction

The liberation of building rubble by comminution produces a predominantly mineral mixture with adensity distribution ofs = 1.8 - 2.7 g/cm

3 [32]. As a result of the relatively narrow density range,the requirements regarding the sharpness of the process employed for the separation of partiallyliberated aggregate and concrete-brick rubble are very high.

Table 1: Selected separation processes for the recycling of building and domestic waste

Wet separation Dry separation Float and sink cleaning [36],

[29] Upward flow [12]

Jig [4], [13] Washing drum [10]

Classification [7] Hand sorting [9] Automatic sorting [27]

Counter-, cross-flow aeroseparation [22] Pneumatic table [8] Sloping separating belt [27] Slinger [9] Eddy current separator [26]

The separation processes currently employed in the recycling of building materials remove mainlythe lightweight impurities such as paper, wood, films, insulating materials and pieces of plastic(s = 0.1 - 1.2 g/cm

3) by wet or dry separation. In such cases, the range of unsharpness of the cut-point can be defined in the intermediate range (s = 1.2 1.8 g/cm

3), so that equipment with rela-tively low separation efficiency is still adequate for these applications. Table 1 provides an over-view of the state-of-the-art in respect of separation for recycling building materials [1], [5], [9],[13], [14], [22], [36].


2/13

Wet and dry separation have different advantages and disadvantages. Dry separation is more cost-effective in terms of its energy requirement as problems regarding the treatment of process waterand its disposal do need to be considered, and is especially suitable for mobile and semi-mobile

processing plants. Wet separation is useful for the removal of pollutants from contaminated build-ing waste [12].

For the separation of building rubble, mainly classifiers are used in practice. The upward flow orsingle-stage cross-flow separators commonly employed for dry separation in an air flow separatethe material feed according to the respective settling velocities of the different components. Theseparation behaviour is influenced decisively by the particle size, particle shape and particle densityof the components to be separated. An air classifier can separate the material according to one ofthese parameters providing the influence of the other two variables is minimised.The separation of totally or partially liberated aggregate particles in the size range from d = 2 - 16mm therefore presents a challenge to the separation sharpness and the efficiency of the equipment.Tests were carried out in a zigzag channel to establish whether the high separation sharpness re-quired can be achieved in a multistage turbulent cross-flow separation apparatus.

2 Fundamentals of the Aeroseparation of Building Rubble

The basis for studying a separation process in a fluid cross-flow is the balance of the forces ofbuoyancy, weight and fluid resistance of a particle. With this balance, it is possible to obtain a cor-relation between particle size and the quasi-stationary settling velocity vs in the field of gravity g:

gA

V

c

2v

p

p

f

fs

W

2s

= (1)

Here Ap is the side-fed cross-sectional area, cW the drag coefficient of the fluid flow pattern aroundthe particles, Vp the particle volume and f the fluid density. The density of the solid particles s

depends on the inner porosity (up to 95 % for insulating materials) and pore saturation with a liq-uid.In the separation of particles of varying density s the principle of what is termed equivalent fallingclasses [25], i.e. classes with equal settling velocity, can be formulated as follows. If the particleshape is constant, large and lightweight particles settle just as fast as small and heavy par-ticles. With di to di+1 as the particle size of the class i to i+1 as well as s,S and s,L as the particledensities of the heavy fraction (index S) and the lightweight fraction (index L), the following ap-

plies:

),d(v),d(v S,sisL,s1is =+ (2)

Depending on the particle flow patterns [24] and with the relationship dvs cW

Re

1 2

3

(particleReynolds number ffs dv=Re ), it then follows, Table 2:

Table 2: Equivalent-falling condition dependent on the particle flow-around pattern

Exponent

+3

1 Flow pattern Reynolds number Drag coefficient

2 1/2 laminar (Stokes) Re < 1 cw Re-1

2 < < 1/2 1/2 ... 1 transition 1 < Re < 103 cw Re-1...0

1/2 1 turbulent (Newton) 103 < Re < (2 - 4).105 cw Re0


3/13

+

+

=

3

1

fL,s

fS,s

i

1i

d

dor

3

1

fT,s

fs

TsT

s

d

d

v

v+

=

= (3)


4/13

Table 3: Separators with turbulent fluid flow [24], 1) re-calculated from separation results

Cross-flow separationapparatus

ApparatusReynolds no.

= /DuRe

Degree of tur-bulence

u/'uTu 2=

Turbulent diffusioncoefficient in(cm)2/s

2t 'uD =

Bodensteinnumber

s,ts D/LvBo =

Screw classifier

2SS Dn

Recrit 104

104 - 5105

0.05 0.15

5 50 or (2)2 - (7)2

100D

Dn

t

2SS

Rake classifier

2RR Ln

104 - 5104

-

30 100 or (5,5)2 - (10)2

35.1D

Ln

t

2RR

1.3 Cyclones

CDu

Recrit 103

105 - 106

0.01 0.05 0.1 at input

Hydrocyclone:

C4 Du108

Aerocyclone:

CDu0035,0 1 - 20 or

(1)2 - (4,5)2

3

t

C 10D

Du

1.4 Zigzag

separator1)bu

104 - 6105

bu

DTu t

0.11 - 0.13

bu)13.011.0( 2000 4000 or (45)2 - (63)2

151D

bu

t

2. Counter-flowclassifier

Du

103 - 106

- Du02,0 200 2000 or (14)2 - (45)2

0.5 - 50

B

V48,0Dn014,0 F2SS

&+

VF.

B

Ds

.V

ns

B

V48,0Ln31,0 F2RR

&+

VF

.

LRnR

B

VF.

u

.V

VG.

Dc

.V

VL.

VS.

u

b

uVF.

.V

VG.

u

D

As the models of counter-current separations drawn up so far [6], [3] have proven unsuitable or toocomplex [30] for the evaluation of the multistage cross-flow gravity separation studied here, in or-der to describe the process efficiency, the separation tapping model of a turbulent cross-flow hydro-


5/13

classification developed by Schubert [23] and Neee [16] was supplemented with a model for mul-tistage turbulent cross-flow aeroseparation [34].Provided that the particle and fluid flow characteristics are more or less equivalent [18], [24], 27]the effective dimensionless turbulence variables can be calculated from the separation results de-scribed in the following, namely the averaged channel Reynolds number Re = ub/ 104 - 6105

and degree of turbulence Tu 0.11 - 0.13, Table 3. Because of the comparable high degree of tur-bulence in the zigzag channel the turbulent particle diffusion or eddy diffusion coefficient of fluidDt,s Dt (45 cm)

2/s - (63 cm)2/s measures also high. Additionally, the amounts in brackets can bephysically correct interpreted as the local particle position shift squared, averaged and related to atime increment, i.e. 2nd statistical momentum of particle concentration distribution, see Einstein orFokker-Planck-Equation [19]. Consequently, the ratio of convectional to diffusive particle transportexpressed by means of the Bodenstein number Bos Bo = ub/Dt 1 15 is comparably small.Solving the Fokker-Planck-Equation for one-dimensional steady-state particle transport an alge-

braic formulation of particle number concentration distribution in a process chamber is found [15].Balancing now the particle flow in the zigzag channel and taking into account the turbulent particle

flow-around pattern in the zL overflow separation stages or zS in the underflow, resp., the normal-ised separation function results as follows ( LV& , SV& total volume flow rates of lightweight and heavy

particles) [35]:

fT,s

fj,s1

S

L.constd

fT,s

fj,s

Sz,Lz

V

V1

1T

=

+

=

&

&

(4)

This fractional grade function Eq.(4) corresponds to a probability distribution of a class j of themeasurable density of the porous particles s,j (the pore space in hardened cement paste measures

around 20 ... 30 %) being discharged in the heavy fraction S. In his case, the cut-point (averageseparation density) is defined with TzL,zS(s,T) = 0.5 probability. For equal fractional grade efficien-cies of the zL lightweight fraction separation stages and zS heavy fraction separation stages, thecomponent mass balance returns the total separation probability (feed index A, [35]):

( )( ) (

( ))S

S

L

L

z

j,z

z

j,zsA

sSS,m

j,A

j,S

j,tot

T

T11

1

q

qR

m

mT

+

=

==

&

&(5)

For a symmetrical separation with the same number of stages in the lightweight and heavy particleflow (zL = zS = z), the total separation function can be simplified with Eqs.(4) and (5) to [35]:

z1

S

L

tot,j

fs,T

fs,j

V

V1

1T

+

=

&&

(6)

Hence, the slope of the separation function can be characterised by an elegant analytical formula-tion of the overall separation sharpness:

( )( )

2

SL

SL

75,s

25,stot

3lnV/Vlnz

3lnV/Vlnz

+

=

= &&

&& 1 (7)

Separation in the turbulent particle flow pattern can only be achieved with appropriate separationsharpness if the separator has a comparably high number of separation stages and if a sufficiently


6/13

high ratio between the lightweight and heavy material volume flow rates V SL V/&& can be maintained.

This is commensurate with practical experience gained with classification, see Kaiser [11]. Becauseof this fact, the multistage separation model is to be generalised for a wide range of flow patternconcerning the characteristic particle settling velocity, Table 4.With the effective total number of separation stages ne (the feed separation stage both in the over-flow and the underflow is included in this number),

1z2n ee = (8)

an additional degree of freedom z = ze is obtained, which, on the one hand, can be used to fit themeasured values to a physically valid separation function Eq. (6) especially with regard to their S-shape. On the other hand, the so-called separation stage utilisation coefficient represents an addi-tional parameter to assess separation efficiency in case of small density differences.

T = ne/n (9)

Table 4: Assessment characteristics for multistage cross-flow separation in a symmetrical apparatus with zo = zu = z

number of separation stages and see Table 2Separation functionTtot(/T) =

Cut characteristicT = 50(Ttot = 0,5) =

Separation sharpnesstot = 25/75 =

Fluidflowseparation = vs

( )( )

z,dv

,dv1

u

osTTsT

ss

V

V1

1

+ &

& ( )

T,PfT,W

T,PfsTsT

Ac

gV2v

=

( )( ) 3lnV/Vlnz

3lnV/Vlnz

uo

uo

+

&&

&&

Classifi-cation

= ds= const.z

d

d1

G

FT

VV1

1

+ &

&

2

G

Fs,t

s

fT

V

Vln

h

D

g3

d

&

&

for spheres cW = 0,44

( )

( )

+

1

GF

GF

3lnV/Vlnz

3lnV/Vlnz

&&

&&

Gravityseparation = sd = const.

z1

S

L

3

1

fT,s

fj,s

V

V1

1

+

+ &

&

2

S

Ls,tfsT

V

Vln

h

D

gd3

&

&

for spheres cW = 0,44

( )( )

1

3

SL

SL

3lnV/Vlnz

3lnV/Vlnz +

+

&&

&&

LFo V,V,V &&& overflow, fine or lightweight particle suspension volume flow rates

SGu V,V,V &&& underflow, coarse or heavy particle suspension volume flow rates

= 2 laminar (Stokes), = 0.5 turbulent (Newton) flow pattern acc. to [24] dvs

3 Set-up of the Test Rig

For the separation of mineral materials, a test rig, consisting of a zigzag channel measuring173200 mm, a feed unit, a fan, a cyclone and cloth filter, was set up, Figure 1.The separation process can be observed through the glass side walls of the channel. The mass flowrates of the feed materials and the separation products are determined by means of weight cells. Inaddition, during the tests, the air volume flow rate, the average channel velocity, the pressure dropversus the zigzag apparatus, the pressure drop versus the filter and the temperature and relative hu-

midity at significant points can be measured, Figure 2 (5 1996).


7/13

Zigzag classifiers are usually classed as counter-current classifiers [3]. The separation process inthe zigzag channel can, however, also be understood as a series arrangement of cross-flow separa-tion stages [25]. In each stage, so-called vortex rolls are formed, to which one fractional grade can

be assigned respectively in the ideal case [30].

floor of hall0

-4000

floor of cellar

feed

Zigzag Apparatus

light product heavy product filter light product

Figure 1: Setup of the test rig

filtercyclone

feed

filter-dustlight product

frequencyconverter

air

fan

zigzag apparatus

heavy product

TI

4

FI

3

PI

2

MI

1

PD

6

WI

6

MI7

TI

8

WI10

WI11

PD

9

bin

Figure 2: PI-flow chart of the test rig

Usually the feed material is added to the separation process at the centre relative to the number ofstages in the zigzag channel. In each stage of the apparatus, separation into a lightweight and heavyfraction takes place. The heavy particles slide down the downwards sloping channel walls and thelightweight particles are swept up with the air flow at the two upwards sloping channel walls. At the

bends of the zigzag channel, these two currents cross the channel so that a cross-flow separation

takes place. The good separation characteristics of a zigzag separator are based on the series ar-rangement of several such stages [11], [30], [6], [3], [5], [31], [33].


8/13

4 Assessing the Separation Model for Air Classification

0

0,25

0,5

0,75

1

particle size d in mm

separation

function

T(d)

0,6 1,0 10,0 30,0

sand/splitdT = 2,1 mmu = 7,5 m/sne = 1,8

= 0,75splitdT = 4,6 mmu = 8 m/sne= 1,2

= 0,7split/graveldT = 6,6 mmu = 10 m/sne = 1,2

= 0,7

Figure 3: Comparison of the classification results with the separation model according to Eq. (6)

Table 5: Comparison of classification results with the separation model according to Eq. (6)

according to Figure 3 V O X

channel velocity u in m/s 7.5 8 10

air volume flow rate in m/sgV& 0.3 0.32 0.38

particle settling velocity vsT(dT) in m/s 11.5 15.6 18.7mass flow rate m in t/hs& 0.34 0.12 0.16

specific mass flow rateA,s

m& in t/(m2h) 8.5 3 4

particle concentration s,g in g/kg 262 82 94cut size dT in mm 2.1 4.6 6.6separation sharpness 0.75 0.7 0.7effective separation stages ne 1.8 1.2 1.2utilisation of separation stages T in % 26 17 17

pressure drop pZZ in Pa 440 440 700specific energy consumption Wm,ZZ in kWh/t 0.39 1.25 1.72

As part of preliminary studies, the separation model in Eq. (6) was applied for the classification of

sand/split and gravel, Table 5. In Figure 3, the measured values for the three separation experimentswith the cut particle size dT = 2.1; 4.6 and 6.7 mm are shown. Despite reduction by particle shapeimpact, the quasi-stationary settling velocity of spheres vsT at this cut point is higher than the aver-aged channel air flow rate u being characteristically for the predominant cross-flow separation prin-ciple.For the purpose of comparison, the corresponding model curves with fitted, i.e. effective, stagenumbers zL = zS = ze = 1.4, 1.1 and 1.1 are also plotted. With this additional degree of freedom z,the experimental separation processes with the S-shaped curves typical of air classification (s =const.) can be reproduced very well. From these, separation efficiencies of = 0.7 - 0.75 can beread, which can be considered as good (range = 0.6 - 0.8 [21]). However, for this classification,effective stage number in the range ne = 1.2 - 1.8 results.

This means that the seven separation stages of the apparatus are only utilised to a satisfactory extentat T = ne/n = 17% - 26%. Remarkable in technical terms are also the mass flow rates of 3 - 8.5


9/13

t/(m2h) related to the apparatus cross-sectional area and the mass related energy consumption ofonly 0.4 - 1.7 kWh/t, Table 5.

5 Results of Gravity Aeroseparation

Tests on the separation of concrete-brick mixtures were carried out. Figure 4 shows the reproduci-bility of the separation efficiency on the basis of the results of four tests with a 15-stage unit, allconducted under identical conditions (d = 8 - 12 mm).

1.6 1.8 2 2.2 2.4 2.6 2.8

0.25

0.5

0.75

1

particle density s in g/cm

separation

function

T(s

)

Figure 4: Results for the separation of concrete-brick rubble, d = 8 - 12 mm, n = 15

It can be seen that the separation results demonstrate considerable scattering in comparison withclassification according to Figure 3. The plotted model curves limit the range of separation effi-ciency from = 0.67 - 0.91 for ne = 1 7, Table 6.

sep

aration

function

T(s

)


0,00

0,25

0,50

0,75

1,00

1,8 2,0 2,2 2,4 2,6 2,8 3,0

Figure 5: Separation of concrete-brick rubble, d = 8 - 10 mm, n = 7

From a comparison of the separation experiments with narrowly fractionated concrete-brick mix-tures d = 8 - 10 mm (Figure 5), it can be concluded that this scattering is caused by the influence ofthe particle size. Representative for the other tests, Figure 5 shows that the separation model Eq. (6)

can be fitted very well to the measurement results for narrow particle size ranges. The sharpness ofthis separation with the 7-stage unit can be rated as very good with = 0.86. The utilisation of the


10/13

seven apparatus stages T = 54% at an effective number of stages of ne = 3.8 must be rated as satis-factory to good, Table 6.

0,00

0,25

0,50

0,75

1,00

0,9 1,3 1,7 2,1 2,5 2,9

separation

function

T(s

)


Figure 6: Separation of concrete-brick rubble with rubber granulate, O d = 4-5 mm,V d = 5-6.3mm

On this basis, the layout for the separation of a lightweight fraction, here rubber granulate s 1.0g/cm3, is relatively unproblematic, Figure 6. Because of high particle concentration s,g = 417 g/kgadjusted here, a comparably small specific energy consumption Wm,ZZ = 0.19 kWh/t is generallyobtained for the good separation efficiency, Table 6. Satisfactory to very good results were alsoachieved in the difficult separation of a partially liberated aggregate consisting of hardened cement

paste rubble, = 0.66 - 0.94 (31 1997, 1999) at utilisation coefficients ofT = 7% - 87%.

Table 6: Assessment of the gravity separation results

concrete-brick rubble concrete, rubberFigure 6

Particle fraction du,i - do,i in mm 8 - 12Figure 4

8 - 10Figure 5

4 - 5 5 - 6.3

channel velocity u in m/s 14 12.5 8.5 8.5

air volume flow rate in m/sgV& 0.56 0.51 0.35 0.35particle settling velocity vsT(dT) in m/s 20.3 21.7 14.3 14.9

mass flow rate m in t/hs& 0.12 0.15 0.15 0.63

specific mass flow rate A,sm& in t/(m2h) 3.0 3.7 3.7 15.8

particle concentration s,g in g/kg 50 68 98 417cut density s,T in g/cm

3 2.1 2.4 2.1 1.8

separation sharpness 0.7 - 0.9 0.86 0.80 0.78effective separation stages ne 1 - 7 3.8 3 3.4

utilisation of separation stages T in % 7 - 47 54 43 49

pressure drop pZZ in Pa 1600 815 350 350specific energy consumption Wm,ZZ in kWh/t 8.0 2.75 0.83 0.19


11/13

6 Summary

To assess the efficiency of the separation of liberated aggregate particles of concrete rubble frag-ments, the separation functions were determined and compared with a theoretical model of multi-stage turbulent cross-flow separation. Specific mass flow rates 3 to 16 t/(m2h) and mass relatedenergy consumption 0.2 to 8 kWh/t were obtained. On the basis of the well-known separationsharpness, a considerable utilisation of separation stages as well as geometrical variability of a zig-zag apparatus, it could be shown that this multistage cross-flow separation principle is well suitedfor the gravity separation of mineral materials.

7 Symbols and Indices

A area A cross-sectional area related, feedd particle size e effectiveg gravity acceleration f fluidh channel height F fines

m& mass flow rate g gaseousn total number of separation stages G coarseq frequency distribution i particle size fractionT separation efficiency function j particle density fractionu fluid velocity K channelv particle velocity L lightweightV& volume flow rate m mass relatedW work, energy consumption p particlez fraction number of separation stages o overflow exponent s solid, settlingp pressure drop S heavy

utilisation coefficient t turbulent separation sharpness tot total particle concentration T cut-point, separation physical separation characteristic u underflow density ZZ zigzag apparatus

8 References

1 Bilitewsk, B., Vermeidung und Verwertung von Reststoffen in der Bauwirtschaft, Beihefte

zu Mll und Abfall, 30, p. 40 63, 1995.2 Bilitewski, B., Weltin, B., Trennleistung eines Querstromsichters bei der Aufbereitung von

Baustellenabfllen, Vortrag Berg- und Httenmnn. Tag, Freiberg, 1995.

3 Bhme, S., Zur Stromtrennung zerkleinerter metallischer Sekundrrohstoffe, Freiberger For-schungsheft A 785, 1989.

4 Breuer, H., Betriebserfahrungen mit einer luftgepulsten Alljig-Kiessetzmaschine zur Ab-trennung von organischen Verunreinigungen aus Sand und Kies, Aufbereitungs-Technik 29,

p. 324-330, 1988.

5 Friedrichs, J., Tomas, J., Aerosortierung von Bauschutt. In: Arbeits- und Ergebnisbericht desSonderforschungsbereiches 385 Baustoffrecycling Otto-von-Guericke-Univ. Magdeburg,

p. 197 250, 1996.6 Gorzitzke, W., Trockenes Sortieren grober disperser Feststoffe durch Kombination von Sie-


12/13

bung und Windsichtung, Diss. TU Clausthal-Zellerfeld, 1982.7 Greschner, J., Mglichkeiten des Recyclings von Bauschutt, innerstdtischen Aushubmate-

rialien und kohsiven Stoffgemischen mit neuentwickelten Vibrationsrosten, Aufbereitungs-Technik 35, p. 13-24, 1994.

8 Gldenpfennig, M., Lhr, K., Sortierung vermischter Reststoffe gleicher Dichte auf dem

Luftherd, Aufbereitungs-Technik 36, p. 314-320, 1995.9 Hanisch, J., Jckel, H.G., Eibs, M., Zu aufbereitungstechnischen Aspekten des Baustoffre-

cyclings, Aufbereitungs-Technik 32, p. 10 17, 1991.10 Hentzsche, W., Waschen und Lutern zum gegenwrtigen Stand der wissenschaftlichen

Kenntnisse und deren Anwendung, Aufbereitungs-Technik 31, p. 126 130, 1990.11 Kaiser, F., Der Zick-Zack-Sichter - Ein Windsichter nach neuem Prinzip, Chemie - Ing.

Technik 35, p. 273 282, 1963.12 Kalck, U., Werther, J., Zum Einsatz von Aufstromklassierern fr die Aufbereitung kontami-

nierter Baggerschlmme Aufbereitungs-Technik 31, p. 593 601, 1990.13 Kellerwessel, H., Setzmaschinen, besonders fr Recyclingaufgaben - Mglichkeiten, Gren-

zen, Bauarten-, Aufbereitungstechnik 34, p. 521-530, 1993.14 Melchiorre, M., Gldenpfennig, M., Lhr, K., Zrn, J., Teilen und Trennen im Recycling-

Proze, Chem.-Ing.-Technik 66, p. 661 670, 1994.15 Molerus, O., Stochastisches Modell der Gleichgewichtssichtung, Chemie-Ing.-Technik 39,

p. 792 796, 1967.16 Neee, Th. and H. Schubert, Modellierung und verfahrenstechnische Dimensionierung der

turbulenten Querstromklassierung; part I: Chem. Techn. 27, p. 529 533; part II: Chem.Techn. 28, p. 80 83; part III: Chem. Techn. 28, S. 273 278; part IV: Chem. Techn. 29, p.14 18, 1975 - 1977.

17 Neee, Th., Der aufbereitungstechnische Klassiervorgang im turbulenten wssrigen Medi-um, Freiberger - Forsch. - H. A 465, p. 9 50, 1969.

18 Neee, Th., Modellierung der turbulenten Querstromhydroklassierung, Dissertation B, Berg-akademie Freiberg, 1978.19 Planck, M., ber einen Satz der statistischen Dynamik und seine Erweiterung in der Quan-

tentheorie, Ann. d. Physik 53, p. 324 341, 1917.20 Rohr, W., Entwicklung und Betriebsergebnisse auf dem Gebiet der Sortierung und Klassie-

rung mit dem Aquamator, Aufbereitungs-Technik 28, p. 32, 1987.21 Rumpf, H., Mechanische Verfahrenstechnik, Mnchen: Carl-Hanser Verlag, 1975.22 Schubert, G., Stand und Entwicklungstendenzen bei der Sortierung von Schrotten und Ab-

fllen, Paper, 50th Berg- und Httenmnnischer Tag, Freiberger Forschungsheft A 850, p. 1 35, 1999.

23 Schubert, H. and Th. Neee, The role of turbulence in wet classification, Proceedings 10th

Intern. Mineral Processing Congress, London, p. 213 239, 1973.24 Schubert, H., Bhme, S., Th. Neee and D. Espig, Klassieren in turbulenten Zwei-Phasen-

Strmungen, Aufbereitungs-Technik 27, p. 295 306, 1986.25 Schubert, H., Aufbereitung mineralischer Rohstoffe, Band I, Deutscher Verlag fr Grund-

stoffindustrie, Leipzig, 1989.26 Schubert, H., Wirbelstromsortierung-Grundlagen, Scheider, Anwendungen, Aufbereitungs-

Technik 35, p. 553-562, 1994.27 Schubert, H., Aufbereitung fester Stoffe, Band II Sortierprozesse, Deutscher Verlag fr

Grundstoffindustrie, Stuttgart, 1996.28 Schubert, H., On the turbulence-controlled microprocesses in flotation machines, Int. J. of

Mineral Processing 56, p. 257 276, 1999.29 Schtze, H. J., Naaufbereitung von Bauschutt im Aquamator, Aufbereitungs-Technik 28, p.

463 469, 1987.


13/13

30 Senden, M.M.G., Stochastic model for individual particle behaviour in straight and zig-zagair classifier, Ph. D. Thesis, Eindhoven University, 1979.

31 Tomas, J.; Friedrichs, J., Waste building material separation in a zigzag air apparatus, Erz-metall 50, p. 562 571, 1997.

32 Tomas, J., Ehlers, S. Schreier, M., Impact crushing of concrete for liberation and recycling,

9th

Europ. Symp. on Comminution, Albi, p. 57 70, 1998.33 Tomas, J., Schreier, M., Grger, T., Liberation and Separation of Valuables from Building

Material Waste, Global Symp. on Recycling, Waste Treatment and Clean Technology, SanSebastian, p. 461 470, 1999.

34 Tomas, J. and T. Grger, Mehrstufige turbulente Aerosortierung von Bauschutt, Aufberei-tungs-Technik 40, p. 379 386, 1999.

35 Tomas, J. and T. Grger, Verfahrenstechnische Bewertung einer mehrstufigen Querstrom-Aerosortierung mineralischer Stoffe, OvGU Magdeburg, Preprint 1, p. 1 60, 2000.

36 Trnkler, J., Verbesserung der Produktqualitt bei der Bauschuttaufbereitung durch nasseoder trockene Behandlung, Aufbereitungs-Technik 33, p. 194 202, 1992.

particle separation

Documents