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THE SIZING AND SELECTION OFHYDROCYCLONES
By Richard A. Arterburn
For many years, hydrocyclones,commonly referred to as cyclones,
havebeen extensively utilized in the classificationof particles in
comminution circuits. Thepractical range of classification for
cyclonesis 40 microns to 400 microns, with someremote applications
as fine as 5 microns oras coarse as 1000 microns. Cyclones areused
in both primary and secondary grindingcircuits as well as regrind
circuits. Theinformation given in this paper is intended toprovide
a method, at least for estimatingpurposes, of selecting the proper
numberand size of cyclones and to determine theproper level of
operating variables.Generally, it is recommended that
cyclonesuppliers be consulted for sizingconfirmation. Some cyclone
suppliersemploy digital computers to aid in the sizingand selection
of cyclones.
CYCLONE DESCRIPTION AND BASICOPERATION
Figure 1 shows a cutaway view of atypical cyclone. During
operation, the feedslurry enters the cyclone under pressurethrough
the feed pipe into the top of thecylindrical feed chamber. This
tangentialentrance is accomplished by two types ofdesign, as shown
in Figure 2. Since themajority of research has been done with
theinvoluted type, the graphs and relationshipsshown may not be
strictly applicable to otherdesigns.
As the feed enters the chamber, a rotation ofthe slurry inside
of the cyclone begins,causing centrifugal forces to accelerate
themovement of the particles towards the outerwall. The particles
migrate downward in aspiral pattern through the cylindrical
sectionand into the conical section. At this point thesmaller mass
particles migrate toward thecenter and spiral upward and out
throughthe vortex finder, discharging through theoverflow pipe.
This product, which containsthe finer particles and the majority of
the
water, is termed the overflow and should bedischarged at or near
atmospheric pressure. The higher mass particles remain in adownward
spiral path along the walls of theconical section and gradually
exit throughthe apex orifice. This product is termed theunderflow
and also should be discharged ator near atmospheric pressure.
BASIC PARAMETERS FOR STANDARDCYCLONE
The definition of a “standard cyclone” isthat cyclone which has
the propergeometrical relationship between thecyclone diameter,
inlet area, vortex finder,apex orifice, and sufficient length
providingretention time to properly classify particles.As with the
involuted type design, thegraphs and mathematical
relationshipsshown for proper selection and sizing ofcyclones apply
to the “standard cyclone”geometry. The main parameter is the
cyclonediameter. This is the inside diameter of thecylindrical feed
chamber. The next parameter is the area of theinlet nozzle at the
point of entry into the feedchamber. This is normally a
rectangularorifice, with the larger dimension parallel tothe
cyclone axis. The basic area of the inletnozzle approximates 0.05
times the cyclonediameter squared. The next important parameter is
thevortex finder. The primary function of thevortex finder is to
control both the separationand the flow leaving the cyclone. Also,
thevortex finder is sufficiently extended belowthe feed entrance to
prevent short circuitingof material directly into the overflow.
Thesize of the vortex finder equals 0.35 timesthe cyclone diameter.
The cylindrical section is the next basicpart of the cyclone and is
located betweenthe feed chamber and the conical section. Itis the
same diameter as the feed chamberand its function is to lengthen
the cycloneand increase the retention time. For thebasic cyclone,
its length should be 100% ofthe cyclone diameter. The next section
is the conical section,typically referred to as the cone
section.The included angle of the cone section isnormally between
10O and 20O and, similarto the cylinder section, provides
retentiontime.
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The termination of the cone sectionIs the apex orifice and the
critical dimensionis the inside diameter at the discharge point.The
size of this orifice is determined by theapplication involved and
must be largeenough to permit the solids that have beenclassified
to underflow to exit the cyclonewithout plugging. The normal
minimumorifice size would be 10% of the cyclonediameter and can be
as large as 35%.Below the apex is normally a splash skirt tohelp
contain the underflow slurry.
PERFORMANCE
In determining the proper size andnumber of cyclones required
for a givenapplication, two main objectives must beconsidered. The
first is the classification orseparation that is required, and the
secondis the volume of feed slurry to be handled.Before determining
whether these objectivescan be achieved, it is necessary to
establisha base condition as follows:
1. Feed liquid – water at 20O C.2. Feed solids – spherical
particles
of 2.65 sp gr.3. Feed concentration – less than
1% solids by volume4. Pressure drop – 69 kPa (10psi).5. Cyclone
geometry – “standard
cyclone” as described above
CLASSIFICATION
Historically, classification has beendefined as the particle
size of which 1% to3% reports to the cyclone overflow withcoarser
particles reporting to the cycloneunderflow. Recent investigations
havedefined classification as the particle size ofwhich 50% reports
to the overflow and 50%to the underflow, or the so-called D50C
point.Figure 3 shows the typical relationshipbetween particle
diameter and the percentrecovered to underflow. The portion of
thecurve near the 50% recovery level is quitesteep and lends itself
readily to determiningan accurate particle diameter. Examinationof
the recovery curve near the 97% to 99%recovery level shows that the
curve is nearlyhorizontal and a small differential couldchange the
micron diameter considerably.
[Note: The particle size shown on Figure3 and also used for
calculations in this paperis defined as the minimum particle
diameterof a given size band. For example, aparticle that passes a
150 mesh screen (105microns) but is retained on a 200 meshscreen
(74 microns) would actually have adiameter between 74 microns and
105microns. For this paper, the size of 74microns would be used for
particles in thissize range.] Figure 3 also shows that the
actualrecovery curve does not decrease below acertain level. This
indicates that a certainamount of material is always recovered
tothe underflow and bypasses classification. Ifa comparison is made
between theminimum recovery level of solids to theliquid that is
recovered, they are found to beequal. Therefore it is assumed that
apercent of all size fractions reports directly tothe underflow as
bypassed solids in equalproportion to the liquid split. Then each
sizefraction of the actual recovery curve isadjusted by an amount
equal to the liquidrecovery to produce the “corrected
recovery”curve shown in Figure 3. As the D50C point changes from
oneapplication to another, the recovery curvesshift, along the
horizontal axis. In order todetermine a single graph which
representsthe corrected recovery curve, the particlesize of each
size fraction is divided by theD50C value and a “reduced recovery”
curvecan be plotted, as shown in Figure 4. Investigations have
shown that this curveremains constant over a wide range ofcyclone
diameters and operating conditionswhen applied to a slurry
containing solids ofa single specific gravity and a typical
ornormal size distribution such as thoseencountered in most
grinding circuits.Equation 1 gives a mathematicalrelationship which
can be used to calculatethe reduced recovery. This recovery,
alongwith the bypassed solids, is used to predictthe complete size
distribution for theunderflow product.Rr = e4X - 1 (eq. 1) e4X + e4
–2
Where Rr = Recovery to underflow on corrected basis. X =
Particle diameter /D50C particle diameter.
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In designing comminution circuits theobjective is to produce an
overflow from thecyclone which has a certain size
distribution,normally defined as a given percent passinga specified
micron size. An empiricalrelationship shown in Table 1 is used
torelate the overflow size distribution to theD50C required to
produce the specifiedseparation. The relationship of this table
isfor typical or average grinding sizedistributions and may vary
slightly
depending upon the grinding characteristicsof the ore itself.
The separation a cyclone can achievecan be approximated using
Equation 2. TheD50C (base) for a given diameter cyclone
ismultiplied times a series of correction factorsdesignated by C1,
C2, and C3.
(Eq. 2)
D50C(application) = D50C(base)xC1xC2xC3
Table 1. Relationship of D50C to Overflow Size Distribution
Required Overflow Size Distribution Multiplier
(Percent Passing) of (To Be Multiplied Specified Micron Size
Times Micron Size)
98.8 0.5495.0 0.7390.0 0.9180.0 1.2570.0 1.6760.0 2.0850.0
2.78
Example: Produce an overflow of 80% passing 149 microns (100
mesh).
Multiplier from Table 1 at 80% passing = 1.25.
Micron size for application = 149 microns (100 mesh).
D50C required = 1.25x149 = 186 microns for application.
This D50C (base) is the micron size that a“standard cyclone” can
achieve operatingunder the base conditions and is given inFigure 5
or calculated from Equation 3. Forexample, a 25.4 cm (10 in.)
diametercyclone has a base D50C point of 24microns.
D50C(base) = 2.84 x D0.66 (Eq. 3)
Where D = Cyclone diameter in cm.
The first correction (C1) is for theinfluence of the
concentration of solidscontained in the feed slurry. The
graphicalrepresentation of this correction is shown in
Figure 6 and can be calculated usingEquation 4. Figure 6
indicates that the levelof percent solids is extremely important
indetermining the proper separation, as thehigher the concentration
the coarser theseparation. It should be pointed out that
thiscorrection is a relative measure of slurryviscosity and is
affected by such things asthe size of particles present as well
asparticle shape. For example, a feed thatcontains a large amount
of clay would tendto shift this curve to the left and result in
acoarser separation, whereas the absence offines would shift the
curve to the right andresult in a finer separation. Many other
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variables such as liquid viscosity also affectthis
correction.
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C1 = 53-V (Eq. 4) 53
Where C1 = Correction for the influence of cyclone feed
concentration. V = Percent solids by volume of cyclone feed.
The second correction is for the influenceof pressure drop
across the cyclone asmeasured by taking the difference betweenthe
feed pressure and the overflowpressure. Pressure drop is a measure
ofthe energy being utilized in the cyclone toachieve the
separation. It is recommendedthat pressure drops, whenever
possible, bedesigned in the 40 to 70 kPa (5 to 10 psi)range to
minimize energy requirements aswell as reduce wear rates. This is
especiallytrue for coarse separations usuallyassociated with
primary or secondarygrinding circuits. The correction for pressure
drop isshown in Figure 7 and can be calculatedfrom Equation 5. As
indicated, a higherpressure drop would result in a finerseparation
and lower pressure drop in acoarser separation.
C2 = 3.27 x �� -0.28 (Eq. 5)
Where C2 = Correction for influence of pressure drop. �� =
Pressure drop in kPa.
The next correction is for the effect thatspecific gravity of
the solids and liquid haveon the separation. Since the cyclone
doesnot actually achieve a size separation butrather a mass
separation, the specificgravity of the particle is extremely
importantin determining the separation. It isespecially meaningful
in applications wherethe mineral has a higher specific gravity
thanthe gangue material which allows better
liberation of mineral particles at a coarseroverall separation
size. It has been found that Stoke’s law can beapplied to determine
particle diameterswhich would produce the same terminalsettling
velocity for a particle of knownspecific gravity in a liquid of
known specificgravity as compared to a particle of 2.65specific
gravity in water. This relationship isshown in Figure 8 and can be
calculatedusing Equation 6.
0.5C3 = 1.65 GS - GL (Eq. 6)
Where C3 = Correction for influence of specific gravity GS =
Specific gravity of solids GL = Specific gravity of liquid
(normally 1.0)
The cyclone diameter, along with the threecorrections of percent
solids, pressure drop,and specific gravity, are the main
variablesnecessary for preliminary sizing andselection of cyclones.
Other variables, suchas the vortex finder and inlet size, also
havean effect on separation. For example, alarger vortex finder
size would tend tocoarsen the separation, whereas a smallersize
would tend to achieve a finerseparation. Due to this fact, most
cycloneshave a replaceable vortex finder withdifferent sizes
available. Vortex finderdiameters vary from a minimum of about25%
of the cyclone diameter to a maximumof about 45%. The inlet area
also shows thesame effect as the vortex finder, but not
aspronounced. The apex size also has an effect onseparation but the
effect is minor unless theapex is too small and becomes a
physicalconstraint, forcing material into the overflow. Cyclone
retention time is also a minorfactor influencing cyclone
performance.Within limits, increased retention time wouldhelp
achieve a finer separation; whereasreduced retention time would
coarsen theseparation. The retention time of thecyclone can be
altered by either changingthe length of the cylindrical section or
bychanging the cone angle.
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There are numerous other variableswhich also have an effect of
separation;however, these variables are relatively minorand may be
neglected for the preliminarysizing and selection of cyclones.
FLOW RATE
The second main objective which must beconsidered is to provide
adequate cyclonecapacity for the application. The volume offeed
slurry that a given cyclone can handleis related to the pressure
drop across thecyclone. The relationship between flow rateand
pressure drop for several different sizesof standard cyclones is
shown in Figure 9.As shown, the flow rate increases as thepressure
drop increases. In order to utilizethis graph, the pressure drop
used forcalculating the separation is used todetermine the flow
rate for the cyclonediameter which was also used fordetermining the
separation. The flow rate isthen divided into the total flow for a
specificapplication to determine the number of unitsnecessary.
Since the flow rate given in Figure 9 is forwater rather than
slurry, it should bementioned that slurry normally increases
thecapacity of a cyclone over that shown forwater; however, for
preliminary estimatesthis factor can be neglected. This will
resultin the number of cyclones calculated beingslightly higher
than those actually needed.Approximately 20% to 25% standbycyclones
are recommended for operationalas well as maintenance flexibility.
The vortex finder size and inlet area of acyclone also have an
effect on thevolumetric flow rate that a given cyclone canhandle.
Larger vortex finders or inlet areaswould increase the capacity,
whereassmaller vortex finders or inlet areas woulddecrease the
capacity. The shaded area inFigure 9 corresponding to each
standardcyclone gives the approximate range ofcapacity for each
cyclone.
APEX SELECTION
The proper selection of apex size iscritical to proper cyclone
performance. Foreach application a circulating load isnormally
given which establishes theamount of solids which must pass
throughthe cyclone underflow. Experience has
shown that an underflow density of 50% to53% solids by volume is
typical for primarygrinding circuits, whereas an underflowdensity
of 40% to 45% solids by volume isnormal for regrind circuits.
Therefore, anunderflow density can be assumed whichestablishes the
total flow rate that mustreport through each cyclone apex. Figure10
shows the approximate flow rate for agiven diameter apex
orifice.
OPERATIONAL AND DESIGNCONSIDERATIONS
One of the most important considerationsis to insure that
cyclones are installedproperly. A detailed list of “Do’s and
Don’ts”is given in a later chapter.
FEED PIPING AND DISTRIBUTION
A most important consideration for agiven cyclone system is
proper delivery ofthe slurry to the cyclone or cyclones. It hasbeen
found that a pipe size which producesa line velocity of 200 to
300cm/sec (7 to 10ft/sec) is high enough to prevent particlesfrom
settling, even in horizontal sections, butlow enough to minimize
wear. Normally fora single cyclone installation the inlet pipesize
of the manufacturer’s recommendationproduces a velocity in this
area. If the slurry is to be distributed to anumber of cyclones
operating in parallel,extreme care should be given to the designof
the distribution system, and a radial typeof manifold is
recommended. This is asystem where the cyclones are fed from
acentral circular chamber. When properlydesigned the central
chamber becomes amixing area and the line velocity should belowered
to approximately 60 to 90 cm/sec (2to 3 ft/sec). This will help
insure that eachcyclone is fed with the same slurryconcentration as
well as the same particlesize distribution and also will reduce
wearrates. Using the radial manifold also makesit easier to install
standby cyclones. Should an inline type manifold be utilized,the
cyclones do not receive gooddistribution. It is typical that the
high massparticles or coarser particles tend to passthe first
cyclones and report to the finalcyclone. This results in the last
cyclonereceiving a higher feed concentration ofcoarser particles,
which accelerates the
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wear of the last cyclone as well as producesa coarser separation
due to the higher feeddensity. Also, the last cyclone, once
shutoff, becomes difficult to restart because thesolids will tend
to pack into the feed pipe. For applications where the separation
isnot critical or one in which the feedconcentration is extremely
low, an inlinemanifold is acceptable and is much lessexpensive than
the radial type.
MATERIALS OF CONSTRUCTION
Cyclone Construction varies greatly fromone manufacturer to
another, but themajority of the designs includes metalhousings with
replaceable liners withreplaceable liners with the most
suitableliner material varying from one application toanother. It
is also common to utilize severaldifferent lining materials within
the samecyclone to optimize wear characteristics. Natural gum
rubber is the most commonmaterial utilized due to its relatively
low cost,excellent wear, ease of handling, and it isnot fragile.
Applications where gum rubberis not suitable are those where
thetemperatures exceed 60OC or there arelarge amounts of
hydrocarbons present inthe slurry such as oil or other
detrimentalchemicals. Ceramic materials have foundacceptance as
cyclone liners for the apexorifice as well as other areas which
exhibitsevere abrasion. These include areas suchas the lower cone
liner and vortex finder. Nihard has also proven to be anacceptable
wear material, especially forvortex finders and other areas which
requirestrength as well as abrasion resistance. Other elastomer
materials such asneoprene and nitrite are also utilized
whenhydrocarbons are present or when thetemperature exceeds 60OC.
Urethane hasfound acceptance, especially in areas wherethe solids
are relatively fine.
PRESSURE DROP CALCULATIONS
As mentioned earlier, the pressure dropacross a cyclone is
measured by taking thedifference between the feed pressure andthe
overflow pressure. If the overflow isdischarged at near atmospheric
pressure as
recommended, the feed pressure is thesame as the pressure drop.
Cyclone selection provides the pressuredrop required, and for pump
calculations thismust be converted to meters of slurry whichcan
then be added to the static and frictionheads to determine the
total dynamic headfor the pump. Equation 7 is used forconversion of
pressure drop to meters ofslurry.
M = �� x 0.102 (Eq. 7) G
Where M = Meters, slurry. �� = Pressure drop, kPa. G = Sp gr of
slurry.
As stated, it is recommended that boththe overflow and underflow
products bedischarged at atmospheric pressure.Should the overflow
be discharged against apositive head, some of the fluid
whichnormally reports to the overflow is forced toreport to the
underflow. This does not havea major effect on classification but
doesincrease the amount of bypass solids andreduces underflow
density. Should the overflow be discharged at apoint lower than the
feed entrance, apossible siphon can be established whichwould cause
a breakdown in classificationand could bring larger particles into
theoverflow. A large siphon effect couldactually dislodge a worn
liner which in turnwould plug the overflow piping. Siphons canbe
prevented by installing a vent pipe on theoverflow piping of each
cyclone. The underflow should also be dischargedat or near
atmospheric pressure. Should theunderflow be discharged at a
negativepressure, the effect would be similar to apositive pressure
at the cyclone overflow. Ifthe underflow is discharged against
apositive pressure, the amount of flow isreduced and a larger apex
must be selectedin order to insure that the classified solidscan
discharge freely.
SUMP/PUMP DESIGN
Another chapter covers the selection andsizing of slurry pumps
and should beconsulted for more detailed informationconcerning
sump/pump design. Specifically
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regarding cyclone applications, the feedslurry being delivered
to a cyclone should beas steady as possible with regard to
bothvolumetric flow rate and slurry density.Unsteady feed
conditions such as severepump surging or extreme variations in
slurrydensity are very detrimental to good cycloneperformance. In
general, a sump/pumpsystem for a cyclone application shouldhave a
sump with as much depth aspossible and a minimum
cross-sectionalarea consistent with the pumpmanufacturer’s
recommended retentiontime. A sump of this design will
normallyeliminate pump surging by allowing smallvariations in sump
level well above theminimum pump suction level. The
smallcross-sectional area will reduce the buildupof solids in the
bottom of the sump and helpprevent large sections of the settled
solids toslough into the pump suction and plug eitherthe cyclone
feed line or the cyclone apex.Therefore, a tall sump with a small
cross-sectional area provides much smootheroperation.
APEX DISCHARGE PATTERN
An Important part of cyclone operation isbeing able to observe
the type of patternthat the cyclone apex is producing. An
apexoperating at atmospheric pressure shouldproduce a cone shaped
discharge with anangle of 20O to 30O and a hollow center. Ifthe
cyclone consistently produces a highangle cone spray, the apex
orifice should bereduced in size to maximize the slurrydensity
being discharged. On the otherhand, should the cone spray be void
of thehollow center and resemble a “rope”, thenthe apex is too
small and oversize materialmay be reporting to the cyclone
overflow. Inthis case, a larger apex orifice should
beinstalled.
EXAMPLE PROBLEM
Example – Primary Grinding Circuit
Problem: Select the proper size andnumber of cyclones for a rod
mill/ball millcircuit where new feed to the rod mill is 250metric
tons per hour (MTPH) solids. Bothmill discharges join together at
cyclone feedsump and are pumped to cyclones.Overflow is to be 60% -
200 mesh (74
microns) at a minimum of 40% solids byweight. Underflow becomes
ball mill feed.Specific gravity of solids is 2.9 andestimated
circulating load is 225%.
STEP 1. Calculate material balance fromknown information.
Overflow must be 250MTPH at 40% solids.
Overflow:
MTPH solids = 250MTPH water = 375MTPH slurry = 625% solids, wt =
40Sp gr slurry = 1.3551/sec slurry = 128 (2030 USGPM) (1/sec =
liters per second)
Underflow: (based on 2.25 x overflow):
MTPH solids = 562MTPH water = 187MTPH slurry = 749% solids, wt =
75 (assumed atSp gr slurry = 1.9661/sec slurry = 106 (1676
USGPM)
Feed (sum of overflow and underflow):
MTPH solids = 812MTPH liquid = 562MTPH slurry = 1374% solids, wt
= 59.1Sp gr slurry = 1.6321/sec slurry = 234 (3706 USGPM)% solids,
vol. = 33.2 (necessary for separation calculations)
STEP 2. Calculate required D50C forspecified overflow of 60%
passing 74microns.
From Table 1:
Multiplier at 60% passing = 2.08Specified micron size = 74
micronsD50C (application) = 2.08x74 = 154 microns
STEP 3. Calculate cyclone diameterrequired.
First, calculate C1, C2 and C3:
C1 = Correction for feed density = 4.09
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(from Figure 6)C2 = Correction for �� = 1.1 (from Figure 7).
Pressure drop assumed at 50 kPa (7 psi) which would be low energy
and good maintenance.C3 = Correction for sp gr solids = 0.93 (from
Figure 8)
Second, calculate cyclone diameter:
D50C (application) = D50C (base) x C1xC2xc3 (from Equation 2)154
= D50C (base) x 4.09xl.lx0.93D50C (base) = 37 microns
Therefore, from Figure 5 use 51 cmcyclones (20 in.).
STEP 4. Calculate number of unitsrequired.
From Figure 9:
Flow rate for 51 cm cyclone at 50 kPa = 40 1/secTotal feed flow
= 234 1/sec
Therefore, number of units = 234/40 = 5.85 or use 6 cyclones in
operation.
STEP 5. Calculate proper apex size.
Total underflow = 106 1/secUnderflow per unit = 106/6 = 18
1/secFrom Figure 10 each apex should be 9.5 cm (3 ¾ in.)
CONCLUSION
It has been the intent of this paper to providea method for
determining the proper sizeand number of cyclones required for
thedesign of a comminution circuit. The partsof a cyclone and the
geometry whichcomprise a standard cylone were described.Cyclone
performance, as well as thefundamental variables of cyclone
diameter,feed concentration, pressure drop, andspecific gravities,
has been explained. Bothgraphical representations and
mathematicalrelationships have been given for each ofthe
fundamental variables, and cyclone andapex capacities have been
presented.
Other design and installation informationsuch as feed
distribution systems, materialsof construction, pressure drop
calculations,sump/pump design, and apex pattern werediscussed. An
example problem for aprimary rod mill/ball mill grinding circuit
wasalso given. Although the method for determining theproper size
and selection of hydrocyclonesin this paper has proven to be
quiteaccurate, the engineer should still be awareof the fact that
variations in orecharacteristics have an effect on
cycloneperformance. In cases where the slurrycharacteristics are
questionable, pilot plantinformation should be used to provide
moreaccurate cyclone sizing and selection.
BIBLIOGRAPHY
Arterburn, R.A., 1976, “The Sizing ofHydrocyclones, Krebs
Engineers, MenloPark, CA.
Bradley, D. 1965, The Hydrocyclone,Pergamon Press, Oxford.
Gaudin, A.M., 1939, Principles of MineralDressing, McGraw Hill,
New York andLondon.
Lynch, A.J. and Rao, T.C., 1968, “TheOperatint Characteristics
of HydrocycloneClassifiers, “Ind. J. of Tech., 6.
Lynch, A.J., Rao, T.C. and Prisbrey, 1974,“Influence of
Hydrocyclone Diameter onReduced Efficiency Curves,”
InternationalJournal of Mineral Processing, 1, 173.
Mular, A.L. and Bull, W.R. (Editors), 1969,“Mineral Processes:
Their Analysis,Optimization and Control,” QueensUniversity,
Ontario.
Mular, A. L. and Jull, N.A., 1978, TheSelection of Cyclone
Classifiers, Pumps andPump Boxes for Grinding Circuits,
MineralProcessing Plant Design, AIME, New York.
Plitt, L.R., 1976, “A Mathematical Model ofthe Hydrocyclone
Classifier,” CIM Bull. 69,114.
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Tarr, D.T., 1965, “Practical Application ofLiquid Cyclones in
Mineral DressingProblems,” AIME Fall Meeting.
Wills, B.A., 1981, Mineral ProcessingTechnology, 2nd Ed.,
Pergamon Press,Oxford.
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FIGURE 1CYCLONE CUTAWAY
Cylindrical Feed Chamber
Cylinder Section
Conical Section
Apex
Vortex Finder
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Figure IIInvoluted Feed vs. Tangential Feed
Involuted Feed
Tangential feed
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0
10
20
30
40
50
60
70
80
90
100
20 30 40 50 60 70 80 90 100 200 300 400 500
Graph IPar t ic le Diam eter VS. Par t ic le Recovery
Par t ic le Diam eter (Mic rons)
Pa
r tic
le R
eco v
e ry
(% t
o U
nder
flow
)
Ac t ua lRecovery
Correc tedRecovery
D50 Point
Figure 3. Particle Recovery Curves
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Particle Diameter (microns) /D50 (microns)0.2
10
20
30
40
50
60
70
80
90
100
0
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 2 2.5 3 3.5 4 4.5 5
Graph IIReduced Recovery
Parti
cle
Rec
over
y (%
to u
nder
flow
)
Figure 4. Reduced Particle Recovery Curve
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3
4
5
6
7
8
9
10
15
20
25
3 0
35
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 15 20 25 30 40 50 60
Gr a p h I I ICyc lon e Dia m e t e r VS. D50
(For "Typ ic a l " Cyc lon es )
D50
(M
icro
n s)
Cyc lon e Dia m e t e r (In c h es )
Figure 5. Cyclone Diameter versus D50c for Standard Cyclone
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Gra ph IVCor r ec t ion For Feed Con c en t r a t ion
Cor
rect
ion
Fact
or
Feed Con c en t r a t i on (% so l i d s b y vo lu m e)0 5 10 15
20 25 30 35 40 45 50
0
2
3
4
5
6789
10
15
20
30
40
50
60708090
100
Figure 6. Influence of Feed Concentration on Separation
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0 .4
0 .45
0 .5
0 .55
0 .6
0 .65
0 .7
0 .75
0 .8
0 .85
0 .9
0 .95
1
1 .5
2
2 .5
3
Cor
rect
ion
Fa
ctor
Gr a p h VCor r e c t i on Fo r Pr e s su r e Dr op
Pr e s s u r e Dr op (PSI )
3 4 5 6 7 8 9 10 15
20 2 5 30 40 50 60
7 0 80 90 100
Figure 7. Influence of Pressure Drop on Separation
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0.4
0 .5
0 .6
0 .7
0 .8
0 .9
1
1.5
2
2 .5
3
3 .5
4
4 .5
5
6
7
8
9
10
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5
10
Cor
r ect
ion
Fa
ctor
Gr a p h VICor rec t ion fo r So l id s Sp ec i f i c Gra vi t
y
( in w a t e r )
So l id s Sp ec i f i c Gr a vi t y
Figure 8. Influence of Solids Specific Gravity on Separation
-
18
15
30
40
50
60
70
8090
100
200
300
400
500
600
700
800
1,000
5,000
9,0003 4 5 6 7 8 9 10 15 20 25 30 40 50 60 70 80 90 100
Graph VIIPressure Drop VS. Volum et r ic Flow rat e
Vol
um
etri
c Fl
o wra
te (
US
GP
M)
Pressure Drop (PSI)
30" Cyc lone
26" Cyc lone
20" Cyc lone
15" Cyc lone
10" Cyc lone
6" Cyc lone
4" Cyc lone
Figure 9. Water Capacity for Standard Cyclone
-
19
1
2
3
5
7
10
20
30
40
5060
70
80
200
300
400
500
700
10,000
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 2 3 4 5 6 7 8 9 10
Graph VIIIApex Capacity
Diameter VS. Flowrate
Flow
Ra
te (
GP
M)
Apex DiaMeter (inches)
Figure 10. Apex Capacity Curve