20120914 Comparison Between Currently Applied Grinding Technologies

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Agenda

1. Cement Grinding with Loesche Vertical Roller Mills

2. Other Systems for Cement Grinding

3. Former Concerns regarding VRM Cement Qualities

4. The Proven Reality

5. Short Conclusion


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Cement Grinding with Loesche VRM Mills

Worldwide nearly 240 mills with the 2+2 / 3+3 system

About 170 of them are in operation

Loesche cement mills worldwide

LM 63.3+3

LM 56.3+3

LM 56.2+2

LM 53.3+3

LM 46.2+2

LM 41.2+2

LM 35.2+2

LOESCHE Ref.

C/S Mills 11-2011


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Power consumption of ball mill system v/s LOESCHE VRM system(mill, classifier, fan) - OPC grinding

20

30

40

50

60

70

80

90

100

3000 3500 4000 4500 5000

cm/g

kWh/t

Ball millsystem

LOESCHEVRM system


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Power consumption of ball mill system v/s LOESCHE VRM system(mill, classifier, fan) - slag (GBFS) grinding

Ball millsystem

LOESCHEVRM system

2040

60

80

100

120

140

160

3000 4000 5000 6000

cm/g

kWh

/t


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Loesche cement mills worldwide

~ 60% of Mills for more than 1 product

~ 40% of Mills for more than 3 products


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Agenda





5. Short Conclusion


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Other Systems for Cement Grinding

Different Systems


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Agenda





5. Short Conclusion


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Former Concerns re. VRM Cement Qualities

Compared to traditional Ball Mill systems

It was said that Cements producedin a VRM System have a

Higher Water Demand (Standard Consistency)

Retarded Setting Time

Lower Compressive Strength

due to

Steeper Particle Size Distribution (Slope n) Different Particle Shape

Lower Gypsum Dehydration


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Former Concerns re. VRM Cement Qualities


Steeper Particle Size

distribution?

Lower Gypsum

Dehydration?

Different ParticleShape?


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Agenda





5. Short Conclusion


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The Proven Reality

Different Particle Size Distribution

slope n = tan

position

parameter d

particle size (m)

sumo

fresidueQ

(x)(w.-%

)

VRMSystem

Ball MillSystem

More fine material (Over Ground) in the cement produced by

Ball Mill system due to high number of impacts and mill inefficiency

(Slope n: 0,9 - 1,1)

(Slope n: 0,8 - 1,05)


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The Proven Reality

Operational parameters

Dam Ring

Grinding Pressure

Dam Ring Height

Mill Airflow

Classifier Rotor Speed

Table Speed for very high Blaine cements


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The Proven Reality

Options to adjust the inclination n in the PSD Curve.

Simple adjustment options to achieve the desired product

Grinding

Pressure

Mill Air

Flow

Height of

Dam Ring

Classifier

Speed

lower

higher

lower

higher

higher

lower

higher

lowerSlo

pen


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The Proven Reality

Operational Results regarding Particle Size Distribution:

Technical Properties

Mill VRM BM

Separator LSKS O-SEPADensity g/cm 3,164 3,152

Blaine cm/g 4258 4095

Slope, n - 0,93 0,92

Position parameter, d' m 11,7 12,6Water Demand

(Standard consistency)% 28 28,5

A PSD as needed can be easily produced within a VRM System

Same Slope n Same Water Demand


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The Proven Reality

Different Particle Shape

More spherical shaped particles in cements

produced with ball mill systems

More shallow shaped particles in cements

produced with VRM systems

compared to

results in

Higher water demand for VRM systems

The particle circularity is determined with an L/ - ratio

Th P R li


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The Proven Reality


Particle size in cements all below 55 m and 95% below 45 m

52 m

The maximum particle size in

cements is usually between 45

and 55 m depending upon thefineness of the final product and

the slope n.

95% of all cement particles are

usually below 20 and 45 m

depending upon the fineness of

the final product and the slope n.

Fineness: about 4100 Blaine

Th P R lit


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The Proven Reality


Similar particle shapes produced on VRM systems

Circularity of cement particles

are similar for cementsproduced in a ball mill or VRM

system.

The only notable differences

appear at higher particle sizes

>50 m who have no influence

on the strength development!(VDZ 2007)

Circularity

Clinker B 3000 cm/g

Particle size (m)

VRM

Roller press

Ball mill

58

Th P R lit


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The Proven Reality



distribution?

Lower Gypsum

Dehydration?


Not True!

Not True!

Th P R lit


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The Proven Reality

Lower gypsum dehydration

CharacteristicsBall mill(closedcircuit)

Verticalrollermill

Retention time (min) 20 - 30 < 1

Temperature (C) 90 -140 80 -110

(Plaster)

(Gypsum)

(Anhydrite)

Gypsum Dehydration in Ball Mill

Systems is different compared to

VRM systems. This is due to -

resulting in

Better drying of the gypsum, henceconversion into a higher content

of reactive plaster, necessary as a

setting regulator

Higher mill outlet temperature

Longer residence time in mill system

Different gas humidity (negative factor)

The Proven Reality


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The Proven Reality

Simple Counter Measures in a VRM system

Increase mill exit temperature

Increase gypsum content (0,5 1%)

Add a small amount of natural Anhydrite

Add a small amount of plaster

Normal optimisation process by works quality department

Decrease humidity of mill gas flow

resulting in

Same setting behaviour, i.e. same Setting Time and

Compressive Strength

The Proven Reality


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The Proven Reality


Same Cement with the same characteristics

Technical PropertiesMill . / . VRM BM

Separator . / . LSKS O-SEPA

Fineness acc. to Blaine cm/g 4258 4095

Standard consistency % 28 28,5

Setting time, begin min 130 125

Setting time, end min 175 175Compressive strength (W/C 0,5)

[2d] MPa 29,8 29,9

[7d] MPa 38,9 38,6

[28d] MPa 57,1 54,1

The Proven Reality


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The Proven Reality



distribution?

Lower Gypsum

Dehydration?


Not True!

Partially correct, butsimply adjustable!

(Normal Optimisation!)

Not True!

Agenda


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Agenda





5. Short Conclusion

Short Conclusion


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Short Conclusion

Therefore, cements produced with the Loesche Vertical Roller Mill

will totally meet the required local market demands, regarding Water

Demand, Setting Times and Compressive Strength.

With Loesche Vertical Roller Mills Cement can be produced with the

same Particle Size Distribution,

Particle Shapes and Setting Behaviour

as Cements produced in ball mill systems!

BUT much more Energy Efficient, Cost Effective and Flexible

20120914 Comparison Between Currently Applied Grinding Technologies

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