INTERNAL MIXERSINTERNAL MIXERS AND MIXING PARAMETERS

INTERNAL MIXERSINTERNAL MIXERS AND MIXING

PARAMETERS

Richard Jorkasky II

© Kobelco Kobe Steel Group 2011

MIXING

Early Mixers B d P tBody Parts

Finger, Hand, Arm, FootDisadvantages: Temp PowerDisadvantages: Temp., Power

Advanced Mixer DesignsAdvanced Mixer DesignsStick: Wider Temp. RangeRocks: More Power, Crush, etc., ,

© Kobelco Kobe Steel Group 2011© Kobelco Kobe Steel Group 2011

MECHANICAL MIXING

• Single Rotor MixingEarly as 1820sEarly as 1820s

• Two Roll MillsTwo Roll Mills 1835 - Chaffee → Mill, Wood Roll1854 - Iron Replace Wood Rollsp

• Mills Still Used Todayy

© Kobelco Kobe Steel Group 2011© Kobelco Kobe Steel Group 2011

MECHANICAL MIXING

• Mill DrawbacksTime Consuming/Low OutputTime Consuming/Low OutputInter-Batch VariationsLabor IntensiveDirtySafety

• Two Rotor Mixing1865 N R bb1865 - Non Rubber1916 - Fernley H. Banbury


Internal Intensive Mixer

CHAMBER


Hopper (Floating Weight)

● Pneumatic – Compressed Air Most Common (US)Cost Effective (US)Inconsistent Pressure: Fluctuations

● Hydraulic More Common (Asia)( )Cost Effective (Asia)Consistent Pressure, Less NoiseG t I iti l C t B k EGreater Initial Cost, Break EvenNeeds 1’-2’ More Head Space


Types of Intensive Mixers

Internal Intensive Mixers:Chamber Volume: 0 3 - >700 LitersChamber Volume: 0.3 - >700 Liters1000 L., but chamber is not full (550 L)Batch Wt.: 0.5 - 1150 Lbs*Stationary Chamber

Tilt Discharge Mixers:Tilt-Discharge Mixers:Chamber Vol.: 4 - 300 Liters (common) Batch Wt : 6 - 500 Lbs*Batch Wt.: 6 - 500 LbsMoveable Chamber

* Based on a Specific Gravity of 1 Based on a Specific Gravity of 1


BB-270 Internal Intensive Mixer


Tilt Mixer: Economix™

Chamber in Full Discharge PositionChamber in Full Discharge Position


Factors Affecting MixingRotorsRotors

Tangential20+ T f T ti l (2 6 Wi )20+ Types of Tangential (2 - 6 Wing)Master Batch, 2nd Pass, Re-Mill and FinalEven or Friction SpeedThroughput, Dispersion, MooneyThroughput, Dispersion, Mooney

Intermeshing12+ Types of Intermeshing (3, 4 Lobe)Tandem (500 → 1000 L), Adjustable Clear.Master Batch & 2nd Pass with AdditivesEven SpeedEven SpeedHigher Ram Pres. (Stiff Materials 150 psi)Decreased Fill Factor (Stiff Materials 54%)Temp. Sensitive, Dispersion, Mooney


Tangential vs. IMPath of Rotors in the Mix Chamber

Tangential Rotor Paths

Intermeshing Rotor Paths


Material Pull-InIM Hi h R PIM: Higher Ram Pressure

Intermeshing MixerTangential Mixer


Types of Mixing

● Dispersive Mixing

● Distributive Mixing

● Reactive Mixing


Types of Mixing

● Dispersive MixingReduction of Additives from Pellet/ Granule to Aggregate/Particle Size

Agglomerates AggregatesGranule/Pellet


Types of Mixing

• Distributive MixingDistribution of Additive Aggregates/Distribution of Additive Aggregates/Particles Throughout the Matrix

Poor Distribution Good Distribution


Tangential Rotor Mixing

Dispersive Mixing: Distributive Mixing:

WeightRotor Tip to Chamber Wall

gRotor Body to Wall

Rotor Rotor

Drop Door

Dispersive Mixing:Rotor Tip to Rotor Tip

Distributive Mixing: Between Rotors


Intermeshing Rotor Mixing

Dispersive Mixing: Rotor Wing (Nog) to Rotor Body

Dispersive Mixing: Rotor Edge to Chamber Wall

Dispersive Mixing: Rotor Edge to Chamber Wall

Distributive Mixing: Rotor Body to Wall


2 Wing Standard Rotors

• Introduced in 1916

Still Used in Many Plants• Still Used in Many Plants

• General Purpose Mixing / Final

• Slow Temperature Rise

L E C ti• Low Energy Consumption

• Best Rotor for Certain Silica


2 Wing Standard Rotorsg


4 Wing Rotors

Introduced in 1939 (1960s, 2011)

Advanced Rotor Designs (4, 6, IM)Require ~25% More Drive Power

Improved Mixing, But …

Poor Dispersion of Some Additives, Especially Sulfury

Modifications to Wing Angle andRotor Bodyy

4 Wing Standard Rotor: Superior to the 2 Wing Rotorp g


4 Wing Rotor Designs

4 Wing Standard RotorStandard Rotor

(4WS)

4 Wing H Swirl Rotor

(4WH)( )


Mixing Patterns of 4 Wing Rotors

S4 Wing Standard Rotors

4 Wing H Swirl Rotors4 Wing H Swirl Rotors


Advantages of 4 Wing H RotorsRotors

• Material Flows and Circulates Material Flows and Circulates More Smoothly Throughout Chamber

• Mixing Pressure in the Chamber and the Material Itself is More UniformUniform

• Improved Mixing and Dispersion p g pwith 4 Wing H


4 Wing H Swirl Rotorsg


Typical Rotor Features

Sh t WiShort Wing

Long Wing

Typical Rotor Features: Long Wings on One End and Short Wing on Other End of Rotor. Both Short Wings and both Long Wings are identical, having the same wing angle and rotor tip to chamber wall clearances.


4 Wing N Rotor

♦ Asia 2000, N. America 2006

♦ Designed for Final Mixing♦ Designed for Final Mixing

♦ Master Batch, Re-Mill Rotor

♦ Achieves Greater Shear

♦ Very Aggressive RubberFlow

♦ Slower Temperature Rise


4 Wing N Rotor

One Long Wing on Each Rotor has a Small Angle

SWSW

One Long Wing on Each R t h V L A lRotor has a Very Large Angle

Short Wings Alternate Ends, not on Same End as Most Rotors


4 Wing Mixing Patterns

4 Wing H Swirl Rotors4 Wing H Swirl Rotors

4 Wing N Rotors4 Wing N Rotors© Kobelco Kobe Steel Group 2011

4 Wing N Rotor

♦ Temp. Sensitive Materials

♦ Lower Temp / Equal Mix Time♦ Lower Temp. / Equal Mix Time

♦ 5 - 40 F (3 - 22 C) Lower

♦ Mix at Faster Speed (10 rpm)

♦ More Uniform Batch Temp.

♦ Better Mix Qualityy

♦ Lower Mooney


6 Wing “VCMT” Rotor

• “Various Clearance Mixing Technology” (1990s)Technology (1990s)

• “VCMT” uses Various TipClearances along the Long Wings and Short Wings ofWings and Short Wings of the Rotor


6 Wing VCMT Rotor Tips

Small Tip Width Short Wing: Small Tip Width and Clearancep

Small Tip Clearance

Large Tip Width Large Tip Clearanceg p

Medium Tip Width Medium Tip Clearance


Advantages of the Various ClearancesClearances

Small Tip Clearances:Reduces Dead Areas on Mixer SidesImproved Cooling CapacityHigh Shear MixingHigh Shear MixingExcellent Dispersion

Large Tip Clearances:Allows Greater Movement of MaterialImproved Heat HomogeneityDecreased Frictional Heat


Advantages of the VCMTRotors

Overall:

Fastest Cycle TimesHighest ThroughputReduced Energy ConsumptionExcellent Dispersion pGood Temperature UniformityReduced Mixing StepsReduced Mixing StepsReduced Mooney Viscosity


Intermeshing Rotors

• Introduced in 1934 (Present)

• Lower Fill/Smaller ChamberLower Fill/Smaller Chamber

• Smaller Batch Size

• Temperature Profile ~ 2 Wing

• Longer Cycle Times, ↑ RPM

• Greater Energy Use than Tang.

• Good Excellent Dispersion• Good - Excellent Dispersion

• Lower Mooney Vis. with SBR


Intermeshing Rotors


Rotor Batch Size ComparisonBB-16 Mixer

2 Wing Standard 17.7 lit / 28.0 lb

4 Wing N 16.2 lit / 26.4 lb

4 Wing H “Swirl” 16.0 lit / 26.0 lbg

4 Wing Standard 15.7 lit / 25.6 lb

6 Wing VCMT 14 4 lit / 23 8 lb6 Wing VCMT 14.4 lit / 23.8 lb

Intermeshing 14.5 lit / 20.7 lb

Wt. Lbs. = (Mixer Vol.) (Spec. Grav.) (FF) (2.2)

(Based Upon a Spec. Gravity of 1)


Other Rotor Related Items that Affect Mixingect g

Rotor Cooling

Typical Rotor Cooling: Cored Cavity


Other Rotor Related Items that Affect MixingAffect Mixing

Rotor Orientation

• Friction Speed: No Orientation

• Even Speed

2 Wing: No Specific Orient2 Wing: No Specific Orient.

4 Wing: 0, +90, -90 (270)°

6 Wing: 0, +60, -60 (300), 180°


4 Wing Orientation

0° Orientation

90° Orientation90 Orientation


Factors Affecting Mixing

Rotor SpeedSingle or “Fixed”: 40 RPMSingle or Fixed : 40 RPM

Dual: 20/40, 40/60

V i bl 1 M i RPMVariable: 1 - Maximum RPM

MixingMixing“Speed Kills” Mindset

Faster Mix Speed, Poorer Prop.



Drive Speed

Even: Both Rotors Same Speed

60 rpm X 2 = 120 Total Rev /Min60 rpm X 2 = 120 Total Rev./Min.

Friction: 1 Rotor Faster Than OtherFriction: 1 Rotor Faster Than Other

If the friction ratio is 1.15 and the faster rotor is turning at 60 rpm,faster rotor is turning at 60 rpm,60 + 52 = 112 Total Rev./Min.



Type of Rubber

NaturalIntra- / Inter-bale Mooney VariationPre-mastication or Breakdown

SyntheticEPDM, Nitrile, PB, SBR, etc.Some May Need Breakdown, Nitrile “Tailor Made” - No Breakdown

CombinationsUp to 4 Different Rubbers in One Mix



Water Temperaturep

Circulate Water:

Door, Chamber Sides and RotorsSometimes Through the Ram


Water Circulation Through Chamber SideChamber Side



Water Temperature

Circulate Water:Door, Chamber Sides and RotorsS ti Th h th RSometimes Through the Ram

Water Type:ypTemp. Controlled Water (45 - 210 F)Well: Not affected by surface cond.Cit W t (NE Ohi 35 F t 75 F)City Water (NE Ohio: 35 F to 75 F)Tower Water



Additives

Type: Filler, Oil, Sulfur, Chemicals, Etc.

Grade: CB N-121 vs. N-330 vs. N-774CB N 121 vs. N 330 vs. N 774

Amount:<45-50 phr CB 1 Pass Add>50 phr CB 2 Pass Add



Mixing Scheme:

Ri ht Sid URight Side UpRubber First then Additives

Up Side DownAdditives First then Rubber

Additive Addition Filler, Oil, AO, Etc.

Single Pass vs. Multiple Pass



Silica / Silane Mixing:

1st Pass Silanization: Hold

2nd Pass Silanization: Hold2nd Pass Silanization: Hold

Numerous Passes: No Hold

Pre-Treated Silica: No HoldReaction Done During ManufacturingReaction Done During Manufacturing



Ram Pressure / Ram Raises

High PSI: Faster Mix TimesHigh PSI: Faster Mix Times

Low PSI: Slower Mix Times

Ram Raise: Increase Mix Times

Mix With Ram Upp

IM Rotors: Higher Ram Pressure

Dust Stops



Fill Factor:Higher FillgFaster Mix, to a PointToo High, Poor Mix/UnmixedDust Stops

Lower FillLower FillLonger Cycle TimeNormal Fill: Draws Too Much Power Stiff MaterialsSilica: 75% FF → 60% FF



S l UScale-Up:Lab Mixer to Production Mixer

Heat RemovalRotor/Chamber WearChamber/Rotor FinishesDifferent Rotors Rotor Speeds Different PeopleDifferent People

SuccessE i With B th MiExperience With Both MixersUse of Scale Up Mixers (16 L, 35 L)Calculate Speed/Temp. Needed


INTERNAL MIXERSINTERNAL MIXERS AND MIXING PARAMETERS

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