Selection of Dense Medium Cyclone

8/11/2019 Selection of Dense Medium Cyclone

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A th J B


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A th J B

Introduction

The sizing of cyclones for dense medium separation, like most other things inthis industry, is a combination of art and science.

The selection process within itself is not complex, but there are a number offactors which must be taken into consideration to ensure that the cyclone sizewhich has in the best separation efficiency is selected.

Main Cateories

The selection process can be divided into the following main categories i.e.

Inputs

This covers feed parameters, yield, and design parameters which resultin a mass balance.

!iameter

The full range of cyclone diameters which apply to the input data arecalculated.

Constraints

The outputs of the diameter process are then checked against thefollowing constraints:

Top size


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The categories can be graphically depicted as follows:

#ach of the categories will now be considered in greater detail.

Inputs


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#eed

The minimum information reuired is the following:

Tons per hour solids $dry%. &article density of the feed. Top size of the feed being treated.

'n order to ensure the best possible cyclone selection a full feedparticle size distribution is reuired, but is unfortunately not always

available.

$ield

The yield is reuired to determine the cyclone mass balance.

The best possible information can be derived if a feed washability isprovided. This enables the yield to be accurately determined and the

sinks density can be calculated.

(nce again, this information is not readily available for many processesdue to, amongst other factors, the density of separation.

The next test is for the yield to be supplied by the end user. This canbe determined by a mass balance around a plant or the results of pilotscale test work.

'f this is not available, then an estimate will have to be made basedupon similar operations ) applications.

! i P


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!iameters

The next step is to calculate the relevant parameters for all the cyclonediameters which can be used for all the application.

%op si&e

The process starts with the - mm diameter cyclone.


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Figure 1

The cyclone diameter must be incremented until one which can handlethe top size is found.

Cyclone Capacity

" table of cyclone capacities for cyclones fitted with a barrel extensionis shown in Table 1.


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Spigotcapacity

(m3/

-.

4-.

4.

3-.

3.

-.

.

1-.

Standard

5i 2apacity

6.7

13.1

1.

16.3

14./

8.7

1.1

3.3

4.8

38.3

/.7

48.4

37.3

1.

-. 3.-4.7

8.4

.

- 37 4 -1 71 77 81 /

Cyclone !iameter

Figure 2

Please note that both standard and high capacity spigots are available and the

calculation should be done for both. If the available spigot capacity is less than the

required spigot capacity, recalculate N based upon the maximum spigot capacity.

'e Cyclone !iameter

The number of cyclones reuired is the greater of ! and !9. 'f thenumber of reuired cyclones is more than 1, increment the cyclone


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Constraints

The output from the previous category must now be checked against theconstraints that apply to this application.

This is a graphical process to ensure that everything is taken intoconsideration.


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* #iner Comment


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"election

"ll the information reuired to make the final selection is nowavailable.

Materials o- Construction

The standard materials of construction which are available are:


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'f multiple cyclones have to be used, for !, it is possible toensure good distribution. 'f !>4, then it is better to considermodules with individual modules having !,3,4.

Inlet "hape

+here suare and rectangular inlets are available, the followingguidelines apply:

Suare inlets can be used where a large top size must be

accommodated or a low differential is reuired. ?ectangular inlets are used to ensure a high differential. This is

especially helpful for high density separations $>3.% as thecirculating medium density can be reduced and the inventory ofmedium is reduced.

Pulp !istri,ution

+here !>1, a distributor is reuired. " two way distributor can bedesigned to ensure that eual solids and liuid distribution is achieved.0or !>, distribution becomes increasing complex.

!ote that no static distributor can remove a bias which already exists.

#ngineered ceramic tiles are the preferred lining for pulp distributors asthey give good wear life and can easily be designed to fit any

distributor.

E.ample

" l ill t ti th f thi d f ll


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Summary of Results

No

ofCyclones

,TotalVolu 0

!c Inlet shape '"piot capacity

(m/0h)

37 Suare - 38

4 Suare ) ?ect. 3 3

-1 Suare ) ?ect. 6.7

71 Suare ) ?ect. 4.

81 ?ect. 1 /.7

'um,er o- Cyclones

1

36- 34- 3-/-47

3

1

1-

3

m


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Topsize

(mm

Cyclone !iameter

Both the 4 and -1 mm cyclones will be acceptable. 'n termsof distribution, cyclones is better than 3, which would supportthe choice of the -1 mm cyclone. The breakaway size for the-1 mm cyclone is 1.8 mm and the bottom deck is 1.7 mm soperformance will not be sacrificed.

Constraints

%op "i&e

7Suare

?ectangular

- 0eed topsize

4

3-

4/

43 4

34 33

3 3

4 -

1/ 1/

1

- 37 4 -1 71 77 81 /

Cyclone !iameter

32.33/


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Spigot Requirements

Spigotcapacity

(m3/

1.

Standard

5i 2apacity8.7

38.3/.7

48.437.3

?euired

6.713.1

1.

16.314./

1.14.8

1.

3.- 4.7

8.4

1.

.1

- 37 4 -1 71 77 81 /

Cyclone !iameter

'ot a constraint

' 1 2 and !c 1 345 mm

Inlet "hape


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Cyclone o!el

Cyclone

"iameter (mm)

C#$%%&'

#$%

Conclusion

The process ) procedure given provides the designer ) end user with a tool toenable him to properly evaluate and select the correct cyclone for a givenapplication taking all the relevant factors into account.

It all adds up6


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92 95 97 100 103

C#%%&'

#%

88 94

'%%

105 110 115 120 125

'#*

133 137 141 145 149

C$'%%&'

$'%

137 146

'$$

163 171 179 186 193

#%%

207 213 219 225 231

C'%%&'

'%

208 223

#3

249 261 273 284 295

3%$

315 325 334 343 352

C CY CLON ES ( WITH BA RREL) - CAPACITIES ( M3/H Sl urr y )

#ee d 7ead ( as a -uncti on o- Cyclo ne !i ameter )

8! 9! ! 45! 44! 42! 4;! 4

4/- - -1- -6 -4

For Other Co!"t"o# $#e For%ul& ' Sr Root ( H / H* ) + C / C*

& &


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%

246 263

#,*

294 308 322 335 348

3%

372 383 394 405 415

C,'%%&'

,'%

300 321

3%

358 376 393 409 424

3*

453 467 481 494 507

C+%%%&'

+%%

321 343

3

384 402 420 437 454

,%

Selection of Dense Medium Cyclone

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