A NEW DESIGN OF THREE-PRODUCT HYDROCYCLONE · PERFORMANCE OF THREE-PRODUCT HYDROCYCLONE …..819 Table 2: Values of the different opening diameters used in the experimental work Variable

Journal of Engineering Sciences, Assiut University, Vol. 35, No. 3 pp. 815-828, May 2007.

815

PERFORMANCE OF THREE-PRODUCT HYDROCYCLONE Part II: DISTRIBUTION OF WATER RECOVERY IN THE THREE-

PRODUCT HYDROCYCLONE

M.M. Ahmeda, G.A. Ibrahima, and M.G. Farghalyb aMining and Metallurgical Engineering Department, Faculty of Engineering,

Assiut University, Assiut 71516, Egypt bMining and Petroleum Engineering Department, Faculty of Engineering,

Al-Azhar University, Qena, Egypt

( Received March 5, 2007 Accepted May 21, 2007 )

Hydrocyclones are widely used to separate particulates from water at

high throughput because of their simple structure, low cost, large

capacity, small volume, and easy to maintain and control. Hydrocyclones

belong to a class of fluid-solid classifying devices that separate dispersed

material from a fluid stream. The main function of the hydrocyclone is to

obtain the clear liquid as free from solids as possible in the overflow

product and separates the feed solids in the underflow product. This may

be difficult to achieve practically in the conventional (two product)

hydrocyclone. A three-product hydrocyclone that generates a third

product in which the middling particles should be collected for further

treatment is developed. In this paper, the influence of some parameters

such as overflow opening diameter, middling flow opening diameter, and

underflow opening diameter on the water percent recovered in the three

products is investigated. Three regression models relating these

parameters with the water recovery in each product were obtained. An

optimization of the regression models of the water percent recovered in

the underflow product was done. This was carried out to determine the

optimum values of openings diameters (do, dm, and du) which fulfil the

dewatering process conditions in the three-product hydrocyclone.

KEYWORDS: Two-product Hydrocyclone, Three-product

Hydrocyclone, Water % Split in the Three

NOMENCLATURE

OF overflow product

MF middling flow product

UF underflow product

do over flow diameter

dm middling flow diameter

du under flow diameter

Wo water recovery in the overflow

product

Wm water recovery in the middling

flow product

Wu water recovery in the

underflow product

M.M. Ahmed, G.A. Ibrahim, and M.G. Farghaly….

816

INTRODUCTION

Besides a large amount of applications in mineral processing, hydrocyclones has been

used in an increasing number of applications in environmental engineering [1],

petrochemical engineering [2], food engineering [3], electrochemical engineering [4],

bioengineering [5], and pulping process [6] and so on. Recently, the need for slimes

treatment and water clarification is increased rapidly as in the processing operation

where water is used as a dust suppressant in scrubbers, dust collectors, and similar

equipment or as in the metallurgical operations where the fine suspended solids must

be separated from leach solutions to allow for further treatment [7].

Unfortunately, due to the inherent fluid flow characteristics inside the common

hydrocyclone (two-product hydrocyclone), the separation process in the common

hydrocyclone is always accompanied by some inherent disadvantages, such as

unsatisfactory separation sharpness [8,9]. Recent investigations on the fluid flow field

inside two-product hydrocyclones showed that; controlling the structure of the

turbulence in the inner helical flow inside the cyclone should be a key point to improve

the performance of the hydrocyclone. The hydrocyclone used in these researches was

the conventional hydrocyclone which produces only two products (overflow product

and underflow product). Many researchers had attempted to modify the cyclone design

to control the turbulence of the fluid flow inside the cyclone to improve the cyclone

separation especially in the dewatering process [10-12]. In an attempt to improve the performance of the hydrocyclone separation

technique in the dewatering processes; a three-product hydrocyclone has been

developed [13]. The unit has three openings; the conventional two openings and the

additional third opening which was chosen tangentially on the cyclone periphery. This

third opening was termed as the middling flow opening. This paper aims to investigate the performance of the three-product

hydrocyclone in the dewatering process. The influence of some parameters such as

overflow opening diameter, middling flow opening diameter, and underflow opening

diameter on the water percent recovered in the three products is also investigated

SPECIFICATIONS OF THE THREE-PRODUCT HYDROCYCLONE

The new three-product hydrocyclone has three openings; the conventional two

openings and the additional third opening which was chosen tangentially on the

cyclone periphery. This third opening was termed as the middling flow opening Figure

1. The operation of the three-product hydrocyclone is similar to that of a conventional

unit. Feed slurry is introduced under pressure via the tangential inlet and is constrained

by the geometry of the unit to move into a circular path. This creates the opposing

outward centrifugal and inwardly acting drag forces which result in a spiral flow

pattern. An air core develops along the vertical axis that is connected to the

atmosphere through the spigot, but in part created by dissolved air is coming out of

solution in the low-pressure zone [12, 13]. The three-product hydrocyclone produces

three products from the feed stream. These products are overflow product, middling

flow product, and underflow product.

PERFORMANCE OF THREE-PRODUCT HYDROCYCLONE …..

817

Fig. (1): The new design of three-product hydrocyclone used in the

experimental work

EXPERIMENTAL WORK

Test set-up

One hundred and fifteen tests were conducted to evaluate the performance of the three-

product hydrocyclone on a pilot plant shown in Figure 2. The feed slurry consisting of

quartz particles with a density of 2650 kg/m3. The feed size distribution is shown in

Table (1). Feed slurry containing approximately 4.8 solid percent was made up in the

sump. Contents of the sump, solids and water, were thoroughly mixed by agitation. A

100-mm diameter three- product hydrocyclone at a constant inlet pressure of 10 psi

was used. The variable parameters were; the overflow opening diameter in the range

of 14-50 mm, the middling flow opening diameter in the range of 4-12 mm, and the

underflow opening diameter in the range of 10-24 mm while the inlet opening diameter

was kept constant at 14mm with all other conditions.

Table 1: Particle size distribution of the feed sample

size, um -400 +315

-315 +250

-250 +200

-200 +125

-125 +100

-100 + 80

-80 +63

-63

Wt.,% 3 9 19.10 23.50 27.65 8.55 2.10 7.10

Cum.wt.ret. % 3 12 31.10 54.60 82.25 90.80 92.90 100

Testing

After attaining the required pulp conditions (solid to liquid ratio) in the sump,

the slurry pump is turned on and the pulp is fed to the hydrocyclone. During the

steady state operation in the three-product hydrocyclone plant, timed representative

samples were taken simultaneously from the overflow, middling flow, and underflow


818

streams in order to collect the necessary data for performance evaluations. This was

immediately followed by sampling the feed stream. The slurry samples are weighed,

filtered, dried and reweighed. The basic recorded data included solids flow rate, water

flow rate, and particle size distribution. The obtained results were mass balance which

was used for subsequent calculations and interpretations. Various performance criteria

were evaluated, including throughput, sharpness of separation, separation size, and

solids and water percents recovered in the three products. In this paper only the water

balance in the three products has been reported (the solids percent recovered in the

three products were reported previously) [13]. The water percent recovered in the

three products was assessed as a function of the three products openings diameters

(overflow opening diameter, middling flow opening diameter, and underflow opening

diameter).

Fig. 2: A schematic diagram of the rig constructed at the Mineral Processing

Laboratories, Faculty of Engineering, Assiut University

RESULTS AND DISCUSSION

Regression Models of the Water Percent Separated in the Three Products

In the present work 115 experiments were carried out at different values of the three

diameters do, dm, and du as shown in Table (2) to study the effect of these variable

parameters on the water recovery in the three products.


819

Table 2: Values of the different opening diameters used in the experimental work

Variable Value, mm

Overflow diameter 14, 24, 34, 45, 50

Middling flow diameter 4, 6, 8, 10, 12

Underflow diameter 10, 12, 16, 20, 24

Regression Model of the Water Percent Separated in the Over flow Product

The regression model which correlates the water percent separated in the overflow

product (Wo, %) with the variable parameters (do, dm, and du) can be given by the

following expression:

95.23009.0071.000092.0454.006.2123.033.0

57.631.453.0143.0123.00120.0.)(

333222

umoumou

moumuomoumoo

ddddddd

dddddddddddcalcW

………………(1)

Where:

Wo(calc.) = calculated values of the water recovery in the overflow product Comparison of the experimental values of Wo and the corresponding calculated

ones of the different experiments are shown in Fig. 3. The comparison assures that the

suggested regression model fits well the experimental values of Wo with the operating

variables where the obtained correlation coefficient between these predicted values and

the experimental ones was about 0.97.

Fig. 3: Comparison of experimental and calculated values of Wo

To examine the above equation for prediction of the water percent values

recovered in the overflow product, new experiments were carried out using other

conditions (do, dm, and du) different from those used to obtain the regression model.

These conditions are shown in Table (3). Comparison of the obtained experimental

values of Wo and the predicted ones determined from Eq. (1) of the new experiments


820

are shown in Fig. 4 and Table (3). The comparison assures that the suggested

regression model predicts well the experimental values of Wo with the different

operating variables.

Table 3: Values of experimental and predicted water percent recovered in the

overflow product of the new experiments

Exp. No.

do, mm

dm, mm

du, mm

Wo (exp.), %

Wo (pred.), %

Deviation,%

1 14 4 16 38.77 38.43 0.88

2 14 6 24 10.5 10.18 3.05

3 24 12 10 33.03 33.33 -0.91

4 24 12 16 26.1 26.72 -2.38

5 34 4 10 91.66 92.95 -1.41

6 34 8 10 70.5 73.77 -4.64

7 45 4 20 89.57 85.16 4.92

8 45 6 24 75.6 75.84 -0.32

9 50 6 16 86.01 87.90 -2.20

10 50 10 20 52.3 52.75 -0.86

0

20

40

60

80

100

0 20 40 60 80 100

Wo(exp.),%

Wo

(pre

d.)

,%

Fig. 4: Comparison of the experimental and predicted values of Wo of the new

experiments

Regression Model of the Water Percent Separated in the Middling flow Product

The regression model which corrects the water percent separated in the middling flow

product (Wm %) with the variable parameters (do, dm, and du) can be given by the


1.25004.0109.00003.02314.085.2029.031.3

23.14363.0093.001.0057.0002.0.)(

333222

umoumou

moumuomoumom

ddddddd

dddddddddddcalcW

………….... (2)


821

Where:

Wm (calc.) = calculated values of the water recovery in the middling flow product

Comparison of the experimental values of Wm and the corresponding calculated


suggested regression model fits well the experimental values of Wm with the operating




recovered in the middling flow product, new experiments were carried out using other



values of Wm and the predicted ones determined from Eq. (2) of the new experiments


regression model predicts well the experimental values of Wm with the different

operating variables

Fig. 5: Comparison of experimental and calculated values of Wm


middling flow product of the new experiments

Exp. No.

do, mm

dm, mm

du, mm

Wm (exp.), %

Wm (pred.), %

Deviation,%

1 14 4 16 13.16 15.11 -14.82

2 14 6 24 15.95 17.58 -10.22

3 24 12 10 62.54 64.4 -2.97

4 24 12 16 56.27 61.25 -8.85

5 34 4 10 5.25 6.74 -28.38

6 34 8 10 25.26 27.5 -8.87

7 45 4 20 3.07 2.32 24.43

8 45 6 24 10.58 8.98 15.12

9 50 6 16 10.46 6.88 34.23

10 50 10 20 37.16 34.79 6.38


822

0

10

20

30

40

50

60

70

0 20 40 60 80

Wm(exp.),%

Wm

(pre

d.)

,%

Fig. 6: Comparison of the experimental and predicted values of Wm of the new

experiments

Regression Model of the Water Percent Separated in the Underflow Product

The regression model which corrects the water percent separated in the underflow

product (Wu %) with the variable parameters (do, dm, and du) can be given by the


67.17634.1

77.2106.01284.49

4.626.61.)(

u

mo

umo

u

o

m

u

d

ddddd

d

d

dcalcW

…………..(3)

Where:

Wu (calc.) = predicted values of the water recovery in the underflow product

Comparison of the experimental values of Wu and the corresponding calculated


suggested regression model fits well the experimental values of Wu with the operating




recovered in the underflow product, new experiments were carried out using other



values of Wu and the predicted ones determined from Eq. (3) of the new experiments


regression model predicts well the experimental values of Wu with the different

operating variables


823

Fig. 7: Comparison of the experimental and calculated values of Wu


underflow product of the new experiments

Exp. No.

do, mm

dm, mm

du, mm

Wu (exp.), %

Wu (pred.), %

Deviation,%

1 14 4 16 48.07 47.21 1.79

2 14 6 24 73.55 70.63 3.97

3 24 12 10 4.43 4.84 -9.26

4 24 12 16 17.62 17.09 3.01

5 34 4 10 3.9 3.1 25.8

6 34 8 10 4.24 3.43 19.10

7 45 4 20 7.36 10.08 -36.96

8 45 6 24 13.81 11.84 14.27

9 50 6 16 3.52 3.64 -3.41

10 50 10 20 10.53 9.07 13.87

0

20

40

60

80

0 20 40 60 80

Wu(exp.),%

Wu

(pre

d.)

,%

Fig. 8: Comparison of the experimental and predicted values of Wu of the new

experiments


824

OPTIMIZATION OF THE REGRESSION MODEL OF THE WATER PERCENT SEPARATED IN THE UNDERFLOW

PRODUCT

Theoretically, the ideal separation process in the conventional hydrocyclone if it is

used as a dewatering tool is achieved only if all the feed water reports to the overflow

product and all the solids must be separated into the underflow product [9]. The same

manner may occur into the three-product hydrocyclone except that the water will be

divided between the middling flow product and the overflow product. This depends on

the effect of the different parameters on the three-product hydrocyclone.

In an attempt to investigate this manner into the three-product hydrocyclone, the

water percent split in the underflow product given by equation 3 should be minimized.

For minimization Wu, equation 3 is then partially differentiated with respect to the

different variables, i.e. overflow diameter, middling flow diameter, and underflow

diameter. The following equations were obtained

106.04.626.6122

o

u

o

mu

d

d

d

d

d

W

O

(4)

77.284.496.612

mom

u

ddd

W (5)

634.1124.62

2

uou

u

ddd

W (6)

The above equations 4 through 6 are now solved together to obtain the optimum

values of operating variables. These equations were found to have more than one

solution as follows: do = 29 mm ± 5 mm, dm = 6 mm, du = 10 mm which means that the

experiments have lower and higher optimum conditions.

This fluctuation in the value of the overflow diameter may be interpreted as follows: In

the dewatering process, the main aim is to recover most of the feed water into the

overflow product which depends on the effect of different operating parameters of the

cyclone including the overflow diameter. The overflow diameter affects the flow split

in the cyclone, particularly with its relation to the underflow orifice size [14]. Fontein

et al. [15] observed that the air core diameter increases with increasing the overflow

diameter but it is unaffected by changing the underflow diameter. Accordingly,

increasing the overflow opening diameter of the cyclone for a certain limit, keeping the

other entire parameters constant, increases the air column diameter which is a function

of the overflow diameter [16]. This increasing in the air column diameter will result in

increasing of the water volume split in the overflow product, and vice versa.

According to the above explanation, it may be cleared that the change of air column

diameter leads to the fluctuation in the value of overflow diameter obtained from the

optimization results.

To check the results of the water recovered in the three products obtained from

the predicted models at the optimum values of do, dm, and du, new experiments were

carried out at the different optimum values of do, dm, and du. Table (7) shows the


825

predicted values of Wo, Wm, and Wu calculated from equations 1 through 3 compared

with those values obtained from the corresponding experimental ones.

Table 7: Predicted and experimental values of feed water recovery in the three

products at optimum values of do, dm, and du

do ,

mm

dm,

mm

du,

mm

Predicted Values, %

Experimental Values, %

Wo Wm Wu Wo Wm Wu

24 6 10 76.81 20.08 7.77 80.16 18.19 1.65

34 6 10 86.49 13.54 3.6 85.25 14.35 0.40

Comparison the predicted values of Wo, Wm, and Wu obtained at the lower and

upper optimum conditions with those obtained from the experimental work revealed

that, the difference between them is ranging from 0.81 to 6.12% which may be due to

disturbance in the bottom of the cyclone because the meddling flow opening and the

underflow opening are close to each other.

The results showed that the sum of feed water percent predicted in the three

products is about 104.66% and 103.63% at the lower and upper optimum conditions,

respectively instead of 100%. So the difference was less than (5%) which is

considered within the acceptable range and may be attributed to approximation in the

regression models

Solids and water distributions in the three products

The solids and water percent of the produced three products (overflow, middling flow,

and underflow) for different experiments were calculated for each product from the

mass balance between the feed and products pulp. The obtained results are illustrated

in Table (8).

These results showed that, the three-product hydrocyclone can be used to

produce three products different in their solids and water distributions. The

characteristics of these three products can be summarized as follows:

1. The overflow was a very dilute product with a water percent reaches up to 97% and

solids percent down to 8%.

2. The middling flow has a moderate pulp product where the water percent (ranges

from 3 to 18%) and the solids percent (ranges from 5 to 27%), and

3. The underflow product has a very thick pulp with a water percent down to 0.40%

and solids percent reaches up to 84%.

CONCLUSIONS AND FURTHER WORK

1. Regression models expresses the feed water percentage separated in each product

as a function of the overflow diameter (do), the middling flow diameter (dm), and

the underflow diameter (du) were obtained.


826

Table 7: Values of solid % and water % of the three products obtained for

different experiments

Exp. No.

do, mm

dm, mm

du, mm

Variable OF MF UF

1 24 4 10 water,% 88.81 7.86 3.33

solid,% 12.66 15.63 71.71

2 24 4 12 water,% 86.24 8.41 5.34

solid,% 7.83 13.8 78.37

3 24 6 10 water,% 80.16 18.19 1.65

solid,% 8.28 21.14 70.58

4 34 6 10 water,% 85.25 14.35 0.40

solid,% 9.11 26.91 63.98

5 45 4 16 water,% 94.17 3.21 2.61

solid,% 12.69 6.46 80.85

6 45 4 20 water,% 89.57 3.07 7.36

solid,% 11.9 5.73 82.37

7 45 4 24 water,% 87.4 3.1 9.48

solid,% 11.19 5.3 83.51

8 50 4 10 water,% 96.66 7.66 1.67

solid,% 10.54 20.9 68.56

9 50 4 12 water,% 93.23 4.6 2.16

solid,% 12.72 16.36 70.92

10 50 4 16 water,% 92.64 4.14 3.21

solid,% 13.34 13.02 73.64

2. Comparison of the experimental values of feed water recovery in the three

products (overflow, middling flow, and underflow) and the corresponding

predicted ones assures that the multi-variable models can fit well the experimental

values of feed water percent with the operating variables where the obtained

correlations coefficients were higher than 0.95.

3. The dewatering process can be achieved through three-product hydrocyclone. This

occurred at the optimum values of opening diameters (do = 29 ± 5 mm, dm = 6 mm,

and du = 10 mm) obtained from the minimization of feed water percent separated in

the underflow product, which is confirmed experimentally.

4. Further tests are being conducted to investigate a range of design and operating

parameters on the performance of the new hydrocyclone.

REFERENCES

1. Dwari, R.K, Biswas, M.N., Meikap, B.C, "Performance characteristics of sand

FCC and fly ash in a novel hydrocyclone", Chemical Engineering science Vol. 59,

pp. 671-684, 2004.

2. Chu, L., Y., Lee, X.Z., and Chen, W.M., "Energy consumption and its reduction in

hydrocyclone separation process Part I: Theoretical investigation of pressure


827

distribution and energy consumption mechanism in hydrocyclone", Proceedings of

the seventh world filtration congress, Vol. I, Budapest, 1996.

3. Adupeasah, S.A., Diosady, L.L., and Rubin, L.J., "A multistage hydrocyclone

stirred-tank system for counter current extraction of canola oil", Journal of the

American Oil Chemists Society, Vol. 70, pp. 755-762, 1993.

4. Trim, D.S., and Marder, R.C., "Investigation of hydrocyclones for concentration of

cassava milk", Starch-Stark, Vol. 47, No. 8, pp. 306-311, 1995.

5. Dhamo, N., "An electrochemical hydrocyclone cell for the treatment of dilute-

solutions –approximate plug-flow model for electro deposition kinetics", Journal of

Applied Electrochemistry, Vol. 24, No. 8, pp. 745-750, 1994.

6. Li, M., Johnston, R., Xu, L., Filonenko, Y., and Parker, I., " Characterization of

hydrocyclone separated eucalypt fibre fractions", Journal of Pulp and Paper

Science, Vol. 25, No. 8, pp. 299-304, 1999.

7. Visman, J., and Hamza, H.A, "Application of flocculants in hydrocyclone

separator", CIM Bulletin, February Vol. 3, pp.78-85, 1973.

8. Chu, L., Y., Luo, Q., "Hydrocyclone with high separation sharpness", Filtration

and Separation, Vol.31, No.7, pp. 733-736, 1994.

9. Svarovsky, L., "Solid-Liquid Separation Processes and Technology", Elsevier,

Amsterdam, 1985.

10. Chu, L., Y., and Chen, W., M., "Research on the motion of solid particles in the

hydrocyclone", Separation Science and Technology, Vol. 28, No.10, pp. 1875-

1886, 1993.

11. Obeng, D., P., and Morrell, S., "The JK three-product cyclone performance and

potential applications", Int. J. Miner. Process, Vol. 69, pp. 129-142, 2002.

12. Mainza, A., Powel, M.S., and Knopjes, B., "Differential classification of dense

material in a three-product cyclone", Minerals Engineering Journal, Vol. 17, pp.

573-579, 2004.

13. Ibrahim, G.A., Ahmed, M.M., Farghaly, M.G.," a new design of three-product

hydrocyclone: distribution of the feed constituents in the product streams", under

publication

14. Svarovsky, L., "Hydrocyclones", Technomic Publishing Co., Lancaster,

Pennsylvania, pp. 113-114, 1984.

15. Fontein , F. J., Van Kooy, J. G. and Heniger, H.A. Brit. Chem. Engng.,7, 410,

June, 1962.

16. Trawinski, H.F., "New hydrocyclone for classification and sorting", Technical

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828

أداء الهيدروسيكلون ثالثي النواتج

الجزء األول: توزيعات فصل المياه في الهيدروسيكلون ثالثي النواتج

لصيلبة عملييا فصيل المكوتيا افي واسعة األستخدام جهاز الهيدروسيكلون من أهم أجهزة الفصل يعتبر

باالضييافة والييتمكم صييياتةال و لتشيي يلركيييو و اة التصييميم و التلو سييهلو ليي ميين الميييا فيي خلييية الت يييةهيي المكوتيييا لرئيسييي ميين اسيييتخدامه فيي هييي العمليييا هيييو المصييول علييي ال ييرا اه. صيي ر مجميييل

. مييين هييي ا المتةلييير هييير فكيييرة تصيييميم جهييياز بكفييياعة عاليييية )المكوتيييا الصيييلبة و السيييائلة المختلفيييةالمبيبييا ركييز فيييهمتييتم وسييية تتعليي لييه المصييول هيدروسيييكلون جديييد ) ا يي التييواتم يمكيين ميين خا

بعا عواميل تيم دراسية تير ير في هي ا البمي . لي بعيد ا يمكين معالجتهيالتي المجيم والصلبة المتوسةة )قةر فتمة الخيرو العلويية و قةير فتمية الخيرو السيفلية و قةير فتمية الخيرو المتوسيةة التش يل م لالت يتم فصيلها في المتتجيا ال ا يةم وتيم اسيتتباة معيادال عامية مين التتيائم المعمليية الماععل تسبة

والتي dm, du) (do ,تعبر عين هي ا التير ير كميا تيم اسيتتباة قييم األقةيار الم لي للفتميا ال ا ية المختلفيةلتتيائم أيضيا أتيه . كميا أ هير اداخيل الجهياز الجدييدتيز المييا مين الخليية أعة أفضل تتيجة لعمليية

يمكن باستخدام الجهاز الجديد المصول عل ا متتجا مختلفيه عين بعضيها اليبعا مين ميي تسيبة ل بكفاعة جيدة. ف كل متتم من المتتجا ال ا ة و تسبة المادة الصلبة الماع و

Documents

A NEW DESIGN OF THREE-PRODUCT HYDROCYCLONE · PERFORMANCE OF THREE-PRODUCT HYDROCYCLONE …..819 Table 2: Values of the different opening diameters used in the experimental work Variable