grinding theoretical and technological - midra

UNIVERSITY OF MISKOLC

FACULTY OF EARTH SCIENCE & ENGINEERING

INSTITUTE OF RAW MATERIALS PREPARATION AND

ENVIRONMENTAL PROCESSING

MISKOLC, 2013

GRINDING THEORETICAL AND TECHNOLOGICAL

INVESTIGATION TO ESTABLISH THE PRODUCTION OF

ENVIRONMETAL FRIENDLY CEMENTS WITH REDUCED

CLINKER CONTENT

Theses of PhD dissertation

Author:

Viktória Gável

M. Sc. in Process Engineering,

M. Sc. in Concrete Technology

Scientific tutors:

Prof. Dr. habil. Barnabás Csőke

Professor

Prof. Dr. Ludmilla Opoczky

Titular Professor, Dr. of Chem. Sc.

MIKOVINY SÁMUEL EARTH SCIENCE DOCTORAL SCHOOL

Head of doctoral school: Dr. István Lakatos

Professor, Member of the Hungarian Academy of Sciences

Grinding theoretical and technological investigation to establish the production of environmental friendly cements with reduced clinker content

Viktória Gável

University of Miskolc 2 Theses of PhD dissertation

I. Introduction

The cement is one of the most important building materials of our civilization. Years after the

production technology of portland cement has been chanching and developing, so the variety of

cement produced has been wider. Recently, besides portland cements, so called cements with

reduced clinker content have also appeared that contain a significant amount of cement additives

(granulated blast furnace slag, fly ash from coal firing power station, natural pozzolan etc.) in

addition to clinker and setting regulator. The main reasons of changes of cement variety are the

sharpening market situation, necessity of reducing the cost of cement production, as well as the

effort to meet the requirements of environmental protection, since the reduction of clinker

content of cements is quite important from the point of view of reduction of CO2 emission of

cement industry.

Grinding fineness of cement (specific surface area, particle size distribution) – besides the

chemical-mineralogical composition of clinker – plays a decisive role in the formation of

physical, mechanical properties of cements. The energy consumption of cement grinding to a

defined fineness is basicly influenced by the resistance of mechanical stress, respectively the

grindability of clinker and cement additives besides the parameters of grinding technology (type

of grinding equipment, efficiency of the air separator, application of grinding admixtures etc.).

The grindability of clinker plays an especial important role int he production of cements with

reduced clinker content. This parameter is important not only for that reason because it

influences the operation of grinding equipment, the efficiency and energy consumption of

grinding process, but has significant effect on the fineness and particle size distribution of

cement – including the clinker and cement additives content – by this means on its strength and

application properties, too.

Hungarian researchers have already realized the importance of grinding fineness, respectively

the particle size composition and distribution of portland cements.

According to Beke [1] the texture of clinker has the strongest effect on its own grindability. He

proved that the strength and the rate of strength of portland cement is defined by the particle size

composition [2] that can be describe by the Rosin-Rammler-Sperling-Bennett (RRSB) equation.

He revealed that the two parameters of RRSB equation are the important statistical parameters of

the stochastic process of grinding [3], [4].


Viktória Gável


Opoczky [5] searched for correlation between the grindability, chemical-mineral composition

and texture of clinker for that she investigated deeply the grindability of each clinker mineral [6].

Furthermore she spread Beke’s earlier establishments to the multicomponent cements and over

the mathematical meaning of the parameters of RRSB equation she gave qualitative meaning for

them [7], [8], [9], as well as she proved that in case of production of the multicomponent

cements by co-grinding from materials with different grindability, the grindability of each

component influences the particle size distribution of cement and the distribution of components

in the size fractions [10].

Révay [11] proved by way of experiment that in case of cements containing cement additives

and produced by separate grinding there is no correlation between the ’total’ fraction

composition of cement and the compressive strength at 28 days, however the correlation

established by Beke 40 years before is valid between the fraction of 3-32 m of clinker content

and the strength of cement.

Beke’s and Opoczky’s establishments have been verified by Mrs. Mrákovits’ and Verdes’

experiments [12].

In connection of the effect of changes of the production technology of clinker on the quality of

cement Sas’ [13], Unland’s [14] and Hills’ publications must be highlighted.

Numerous researchers have studied the effect of increasing the hydraulic or pozzolanic activity

of cement additives by grinding on the quality of cement. During my research work in this field I

relied first of all on Opoczky’s [16], [17], [18], Révay’s [11], [19], Csőke’s and Mucsi’s [20],

[21] achievements among Hungarian researchers, Detwiler’s [22], Öner’s [23], Sigh’s and

Middendorf’s [24], [25], as well as Djuric’s and Ranogajec’s [26] achievements among foreign

researchers.

On the base of the evaluation of the literature the following conclusions were made:

Establishments concerning the correlations between grindability, chemical-mineral

composition, texture and production parameters of clinker are contradictory and their

comparing is difficult because of using different grindability indexes. There is no a well

established classification system for qualifying the clinkers based on grindability.


Viktória Gável


The correlations between the grinding fineness and strength of cements and chanching of

parameters of particle size distribution during grinding were investigated mainly in case of

grinding of portland cements without additives.

There are no universally valid rules for choosing the parameters of cements to produce

within the limits of the composition of cements given in the actual cement standards, so it is

nedeed to establish them. The qualifying of each cement additives are difficult.

The content of cement additives in the cements produced in Hungary doesn’t reach the

maximum amount allowed by the standard. The earlier establishments related the

multicomponent cements apply to low content of cement additive and conventional grinding

fineness.

II. The aims of my scientific work

The main aim of my experiments is the complex investigation the production and application

questions of cements with reduced clinker content.

Investigation of correlations between the grindability, texture and production parameters

of clinkers.

Determination of a classification system based on the grindability of clinkers.

Investigation of the quality of the clinker and cement additives – granulated blast furnace

slag, fly ash from coal firing power plant, natural pozzolan (trass) – from the point of

view their effect on the essential properties of cements with reduced clinker content.

Investigation of essential fineness (Blaine specific surface, particle size ditribution) and

qualitative parameters (compressive strength) as well as some application properties

(water demand, sulfate resistance, whitness) of cements with reduced clinker content

produced by co-grinding of clinker and cement additives in connection with additive

content and grinding fineness, establishment of universal correlations.

Development an evaluation method to charicterize the fineness of fly ash and ground fly

ash.


Viktória Gável


Investigation of the role of grinding process – co-, separated and combined grinding - in

the production of cements with rediced clinker content, firs of all in case of cements

containing fly ash, development of grinding process.

III. Experimental and evaluation methods

During my research work I applied scientifically based and internationally adopted – mainly

standardized – testing methods.

Chemical composition of cement clinkers and cement additives were determined by classical

analitical methods.

Phase composition of granulated blast furnace slags was determined and evaluated by XRD

equipment type JEOL JDX 8S, powder diffraction method. For the qualitative and quantitative

analyzation of samples a special software was used.

Fort he determination of grindability I used Zeisel and Bond methods adopted by the national and

international cement industry.

The Zeisel apparatus is a mill consisting of a lower milling dish containing 8 equal size (25 mm

dia) steel balls and an upper rotating ring of variable load. The Zeisel method is based on the

Rittinger law which declars the grinding energy is in direct proportion to the new surface. In the

course of the test – using an increased grinding time – the clinker of a definite particle size

distribution was ground to specific surface of ~5000 cm2/g while the energy consumption was

recorded through moment measurement. From the measured work input the Zeisel ‘specific

grindability’ (Wt) values were calculated.

The Bond apparatus used for the tests is a ball mill with internal dimensions 300 mm by 300

mm filled with 20 kg of various size steel balls. The Bond method models the closed circuit dry

grinding process. The test lasts until the equilibrium state is achieved at the prescribed

circulation factor of 3.5. The value of the Bond work index (Wi) was calculated from the

material quantity ground by each turning of the mill belonging to the equilibrium state, the so

called 'ball mill grindability' from which Bond work index can be calculated.

The texture of cement clinkers were investigated under incident light using an (Olympus C-7070

type) optical microscope. The suitable method of sample preparation was determined by Sas

László János the Head of Quality and R&D of Duna-Dráva Cement Ltd.


Viktória Gável


Blaine specific surface of the ground products was determined by a permeability method.

For testing the particle size distribution I used laser analyser equipments (CILAS 715, CILAS

850 HR and Horiba Jobin Yvon LA-950 type). This equipments are based on the principle of

laser diffraction. I measured the samples in abs. etanol usind ultrasonic dipersation. I evaluated

the results by the RRSB equation, its two parameters: uniformity coefficinet n and fineness

number x’.

Water demand of cements (v) – necessery water to the standard consistency – was determined by

Vicat equipment.

Compressive strength of standard mortar prisms was determined by standard equipment

declaired in EN 196-1 (Tonitechnik type) using central loading method at the age of 2, 7 and 28

days.

Strength efficiency (H) is the proportion of the compressive strength at 28 days of a CEM I type

cement without cement additive and a so called mixed cement made of 80 m/m% of the same

CEM I cement plus 20 m/m% cement additive with the same specific surface.

Sulfate resistance of cements was determined on 40x10x160 mm mortar prisms stored in 4,4

m/m% solution of sodium-sulfate. The expansion of prisms was measured at 28 days by Graaf-

Kaufmann equipment and calculated according to the standard MSZ 4737-1.

Pozzolanic activity was determined by the calcium-oxid absorbed by 1 g pozzolanic sample. The

cummulative value of bonded calcium-oxid is the pozzolanic activity in mg/g.

Whitness of ground material I determined by MOMCOLOR 100 type equipment. During the

measurement I compared the sample with a white etalon (OMH 88-11-00) and the result (X, Y,

Z) evaluated in system CIELAB based on the luminance factor (L*).

IV. Scientific achievements, these

1. I determined the qualification and classification system of clinkers based on the grindability ,

Zeisel ’specific grindability’ (Wt) and Bond ’work index’ (Wi).


Viktória Gável


1.1. Based on the grindability tests of 186 Hungarian industrial clinkers, produced in 1997-2010,

and the mathematical statistical processing of the Zeisel ’specific grindability’ (Wt) of clinkers I

established that the values of Zeisel ’specific grindability’ (Wt) is normally distributed (Figure 1).

Figure 1. Relative frequency histogram of Zeisel ‚specific grindability‘(Wt) of industrial

clinkers produced and investigated in 1997-2010

Based on the statictical parameters of normal distribution – average: x = 37.68 kWh/t; standard

deviation: s = 2.36 – I pointed the limits of grindability areas and rounded these values I

determined the qualification classes of Zeisel ’specific grindability’ (Wt): ’easily’, ’medium’ and

’hardly’ grindable clinkers. Considering Zeisel ’specific grindability’ (Wt) of earlier produced

(in 1975-1996) industrial clinkers (Figure 2) to qualify them I pointed further grindability

classes: ’extremely easily’ and ’extremely hardly’ grindable clinkers (Table 1).

0

2

4

6

8

10

12

14

16

18

20

22

24

31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Rela

tive

freq

uen

cy

[%]

Zeisel 'specific grindability' (Wt) [kWh/t]

Hungarian industrial clinkers (1997-2010)


Viktória Gável


Figure 2. Relative frequency histogram of Zeisel ‚specific grindability‘(Wt) of industrial

clinkers produced and investigated in 1975-2010

Table 1. Classification of clinkers based on the Zeisel ‚specific grindability‘ (Wt)

Corrected, suggested limits

Classification Sign Upper limit

„WtF” [kWh/t]

Lower limit

„WtA” [kWh/t]

> 45 Extremly hardly grindability EH

≤ 45 > 40 Hardly grindability H

≤ 40 > 35 Medium grindability M

≤ 35 > 30 Easily grindability E

≤ 30 Extremely easily grindability EE

1.2 Based on the grindability tests of 178 Hungarian industrial clinkers, produced in 1997-2010,

and the mathematical statistical processing of the Bond ’work index’ (Wi) of clinkers I

established that values of Bond ’work index’ (Wi) is lognormally distributed (Figure 3).

Based on the statictical parameters of lognormal distribution – logarithm of average: ln x = 2.56

kWh/t; logarithm of standard deviation: ln s = 0.15 – I pointed the limits of grindability areas and

rounded these values I determined the qualification classes of Bond ’specific grindability’ (Wi):

’easily’, ’medium’ and ’hardly’ grindable clinkers (Table 2). In respect of Bond ’working index’

(Wi) of clinkers I have no available earlier test results.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61

Rela

tive

freq

uen

cy

[%]

Zeisel 'relative grindability' (Wt) [kWh/t]



Viktória Gável


Figure 3. Relative frequency histogram of Bond ‚work index‘(Wi) of industrial clinkers

produced and investigated in 1997-2010

Table 2. Classification of clinkers based on the Bond ‚work index‘(Wi)

Corrected, suggested limits

Classification Sign Upper limit

„WiF” [kWh/t]

Lower limit

„WiA” [kWh/t]

> 15 Hardly grindability HB

≤ 15 > 11 Medium grindability MB

≤ 11 Easily grindability EB

1.3. The Zeisel ’specific grindability’ (Wt) of industrial clinkers is normally distributed, while the

Bond ’work index’ (Wi) is lognormally distributed that can be explained based on theoretical

consideration by the different grinding fineness of the test methods. Since the Bond method is

typical of the area of coarse grinding therefor it results essentially lower grindability number –

closer to 0 – that limits the distribution of results and deforms the distribution to lognormal. It

can be the explanation of Unland’s (2003) establishment that the Zeisel ’specific grindability’

regarding to lower grinding fineness of ~ 3000 cm2/g is normally distributed.

2. Industrial clinkers belonging to different grindability classes have typical texture that are

determined by the production parameters: composition and grinding fineness of raw meal,

intesity of clinker burning and cooling, type of the fuel, presence and amount of trace elements.

0

2

4

6

8

10

12

14

16

18

20

22

24

26

9 10 11 12 13 14 15 16 17 18 19 20 21

Rela

tive fre

qu

en

cy

[%]

Bond 'work index' (Wi) [kWh/t]



Viktória Gável


2.1. I demonstrated that some of the secondary and trace elements taken into with fuel and/or

alternative raw materials have a favourable effect on the structure and hardness of clinker phases

thus also on the grindability of clinker.

2.2. Based on the complex investigation of industrial clinkers I demonstrated that the coal and

petcoke fuel and by this increased SO3 content of the clinker influences favourably the

grindability (Figure 4) thus the [SO4]2-

ions infiltrated into the alite (C3S) and belite (C2S)

crystals can reduce their micro-hardness [27], [28].

Figure 4. Influence of the type of fuel on the SO3 content and Zeisel ‚specific grindability‘

(Wt) of industrial clinkers

2.3. The most frequently occuring elements in the alternative materials utilized in the cement

industry are chromium (Cr), zinc (Zn), barium (Ba), nickel (Ni), titanium (Ti) and phosphorus

(P) – except the nickel (Ni) – favourable influence the grindability of cklinker since infiltrated

into the clinker phases they can modify their chrystal structure, micro and macro properties, after

all the physical, mechanical properties of clinker. Based on the square mean deviation of

measured values of etalon and trace element containing clinkers I ranked the trace elements

according to their effect on the grindability of clinker (Table 3).

0

5

10

15

20

25

30

35

40

45

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

'Sp

eci

fic

gri

nd

ab

ility

' (W

t) [

kW

h/t

]

SO

3co

nte

nt [

m/m

%]

Date of sampling

SO3 content average SO3 content Specific grindability' (Wt) average 'Specific grindability' (Wt)

100 m/m% natural gas ~90 m/m% coal + ~10 m/m% natural gas

~55 m/m% coal + ~45 m/m% petcoke + ~10 m/m% natural gas


Viktória Gável


Table 3. Ranking of trace elements based on their effect on the grindability of clinker

Effect ont he grindability Order of rank Trace element

Favourable

1 Titanium (Ti)

2 Barium (Ba)

3 Chromium (Cr)

4 Zinc (Zn)

5 Phosphorus (P)

Negligible - Nickel (Ni)

2.4.Based on the complex investigation of industrial clinkers I established that Zeisel ’specific

grindability’ (Wt) is mainly influenced by the clinker micro structure (amount and condition of

clinker minerals) so it can be considered as a material feature while in the formation of Bond

’work index’ (Wi) rather the clinker macro structure (porosity, cracks) plays a decisive role. It

followes from the foregoing that mathematical correlations between the grindability [Zeisel

’specific grindability (Wt) and Bond ’work index’ (Wi)], chemical and mineralogical

composition, as well as the production parameters of clinker cannot be determined but universal

establishments can be stated.

3. In case of production of cements with reduced clinker content by co-grinding the cement

additives influence the particle size distribution [fineness number (x’) and uniformity coefficient

(n)] and water demand (v) of cement. Regarding all three factors the behaviour of cement

containing granulated blast furnace slag is almost the same as the cement without cement

additives. However the behaviour of cements containing fly ash or trass is basically differs from

the behaviour of cement without cement additives.

3.1. In case of co-grinding of clinker and cement additives while the grinding fineness (Blaine

specific surface) is increasing at the same time the fineness number (x’) is reducing even at fine

grinding: Blaine specific surface of 5000-6000 cm2/g (Figure 5/a).

3.2. In case of co-grinding applied the cement additives differently influence the uniformity

coefficient (n) of cement, in fact the granulated blast furnace slag does not influence it up to

Blaine specific surface of ~ 5000 cm2/g but further grinding reduces it a little. However in case

of co-grinding the fly ash significantly increases the uniformity coefficient (n) of cement at each

grinding fineness while the effect of trass is more significant at the Blaine specific surface of

5000-6000 cm2/g (Figure 5/b).


Viktória Gável


3.3. In case of co-grinding applied the cement additives also influence the water demand (v) of

cement however their effect does not change significantly by increasing of grinding fineness

(Blaine specific surface) (Figure 5/c).

a.

b.

c.

Figure 5. Change in fineness number (x‘), uniformity coefficient (n) and water demand (v) as

a function of the grinding fineness (Blaine specific surface) in case of co-grinding of cement

additives and clinker

4. The compressive strength of cements with reduced clinker content significantly decrease by

increasing of the content of cement additive.

8

10

12

14

16

18

20

22

24

26

28

3500 4000 4500 5000 5500 6000

Fin

en

ess

nu

mb

er

(x')

[m

]

Blaine specific surface [cm2/g]

0 m/m% 50 m/m% granulated blast furnace slag

55 m/m% fly ash 55 m/m% trass

Cement additive content

0,7

0,8

0,9

1

1,1

1,2

1,3

3500 4000 4500 5000 5500 6000 6500

Un

ifo

rmit

y co

eff

icie

nt

(n)





20

22

24

26

28

30

32

34

36

38

40

3500 4000 4500 5000 5500 6000 6500

Wat

er

de

man

d(v

)






Viktória Gável


4.1. However the loss of strength caused by increasing of the content of cement additive can be

compensated with increasing of the grinding fineness, between the limits are typical of the

cement additive (Figure 6-8).

Figure 6. Change in compressive strength at 28 days of cements containing granulated blast

furnace slag as a function of blast furnace slag content and Blaine specific surface

Figure 7. Change in compressive strength at 28 days of cements containing fly ash as a

function of fly ash content and Blaine specific surface

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

Co

mp

ress

ive

stre

ngt

h a

t 28

day

s [M

Pa]

Granulated blast furnace slag content [m/m%]

4000

5000

6000

Blaine

specific surface[cm2/g]

CEM III/A CEM III/B CEM III/CCEM II/B-S

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Co

mp

ress

ive

stre

ngt

h a

t 28

day

s [M

Pa]

Fly ash content [m/m%]

4000

5000

6000

Blainespecificsurface[cm2/g]

CEM II/B-V or CEM IV/A (V)

CEM IV/B (V)


Viktória Gável


Figure 8. Change in compressive strength at 28 days of cements containing trass as a

function of trass content and Blaine specific surface

4.2. The compressive strength of cement is decreased mostly by the trass and least the granulated

bust furnace slag, fly ash is between them. The granulated blast furnace slag and the fly ash up to

35 m/m% hardly decrease the compressive strength whereas a small amount trass added cause

more drastic loss on compressive strength (Figure 9/a-b).

a.

b.

Figure 9. Change in relative compressive strength at 28 days of cements with different

grinding fineness (Blaine specific surface) as a function of cement additives content

4.3. Explanation of above is the different activity of the cement additives that rather can be

describe by the activity indexes than the strength efficiency in case of its application to

production of cement containing high amount of cement additive and high grinding fineness

(Table 4).

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Co

mp

ress

ive

stre

ngt

h a

t 28

day

s [M

Pa]

Trass content [m/m%]

4000

5000

6000

Blaine

specificsurface[cm2/g]

CEM II/B-P or CEM IV/A (P)

CEM IV/B (P)

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 10 20 30 40 50 60 70 80 90 100

Rel

ativ

e co

mp

ress

ive

stre

ngt

h a

t 28

day

s [M

Pa]

Cement additive content [m/m%]

Granulated blast furnace slag Fly ash Trass

Blaine specific surface = 4000 cm2/g

0,0

0,2

0,4

0,6

0,8

1,0

1,2

0 10 20 30 40 50 60 70 80 90 100

Rel

ativ

e co

mp

ress

ive

sren

gth

at 2

8 d

ays

[MP

a]

Cement additive content [m/m%]

Granulated blast furnace slag Fly ash Trass

Blaine specific surface = 6000 cm2/g


Viktória Gável


Table 4. Activity indexes of cement additives

Cement additive Activity index Strength efficiency

(H) Ia DIN Ia ASTM

Granulated blast furnace slag from Dunaújváros 1.59 1.26 0.91

Fly ash 0.90 0.38 0.84

Trass 0.64 0.17 0.82

5. The investigation and evaluation method reported in the dissertation which investigates the

material features (activity indexes, composition indexes), grindability indexes and fineness

characteristic values, as well as application propeties (strength, water demand) of clinker and

cement additives at the same time, both in case of co- and separate grinding and evaluates by

functions make possible the control of production of cements with reduced clinker content by

setting of the amount of cement additive and the grinding fineness of cement to achieve the set

quality requirements.

5.1. By the use of nomograms plotted based on the experimental results the composition and

grinding fineness of cements containing granulated blast furnace slag and meeting the

requirements of strength can be designed (Figure 10), while in case of use of fly ash and trass

besides the strength the water demand can also controlled (Figure 11-12).

Figure 10. Connections between the cement additive content and grinding fineness [Blaine

specific surface and fineness number (x‘)] as well as the compressive strength at 28 days of

cement containing granulated blast furnace slag

y = -7,4319x + 153,72

R² = 0,8869

y = -8,2193x + 146,36R² = 0,9077

y = -16,467x + 210,29R² = 0,9426

0

10

20

30

40

50

60

8 10 12 14 16 18 20 22

Co

mp

ress

ive

str

en

gth

at 2

8 d

ay

s [M

Pa

]

Fineness number (x') [ m]

4000

5000

6000

Blaine

specificsurface[cm2/g]

Granulated blast furnace slag content

35 m/m%

50 m/m%

65 m/m%

80 m/m%

95 m/m%


Viktória Gável


Figure 11. Connections between the cement additive content and grinding fineness (Blaine

specific surface) and water demand (v) as well as the compressive strength at 28 days of

cement containing fly ash

Figure 12. Connections between the cement additive content and grinding fineness (Blaine

specific surface) and water demand (v) as well as the compressive strength at 28 days of

cement containing trass

5.2. The different cement additives variously influences the particle size distribution of cements

and hereby they play decisive role in the formation of different quality features of cement. The

granulated blast furnace slag influences first of all the fineness number (x’) of particle size

y = -2,5366x + 125,69R² = 0,8901

y = -2,6371x + 137,35R² = 0,9036 y = -3,1247x + 159,31

R² = 0,9931

25

30

35

40

45

50

55

60

28 30 32 34 36 38 40

Co

mp

ress

ive

str

en

gth

at 2

8 d

ay

s [M

Pa

]

Water demand (v) [m/m%]

4000

5000

6000

Blainespecificsurface[cm2/g]Fly ash content

35 m/m%

45 m/m%

55 m/m%

y = -10,035x + 337,82R² = 0,9547

y = -14,753x + 505,58

R² = 0,9795

y = -7,544x + 279,86R² = 0,915

0

10

20

30

40

50

60

28 29 30 31 32 33 34

Co

mp

ress

ive

str

en

gth

at 2

8 d

ay

s [M

Pa

]

Water demand (v) [m/m%]

4000

5000

6000

Blaine

specificsurface[cm2/g]Trass content

35 m/m%

45 m/m%

55 m/m%


Viktória Gável


distribution and the compressive strength of cement while the fly ash and the trass influence the

uniformity coefficient (n) and the water demand (v) of cement.

6. The quality requirements published in the actual cement product standard is not sufficient to

judge the quality of granulated blast furnace slags. We cannot unambiguously conclude the

hydraulic activity (strength efficiency) from the requirements (amount of glassy and chrystalline

phases, CaO, MgO and SiO2 content) concerning the granulated blast furnace slag as a cement

additive (EN 197-1). The composition of granulated blast furnace slag described by moduluses

(Ma, Mb) and activity indexes (Ia DIN, Ia ASTM) has to be taken into account to characterize the

hydraulic activity and establish the usability of granulated blast furnace slag as a cement additive

(Table 5).

Table 5. Significant quality features of granulated blast furnace slags from Dunaújváros and

Kassa

Dunaújváros Kassa

Activity modulus (Ma) 2

32

SiO

OAl 0.22 0.19

Basicity modulus (Mb) 322 OAlSiO

MgOCaO 1.12

(basic)

0.93

(acidic)

DIN Activity index (Ia DIN) 2

32

SiO

OAlMgOCaO

1.59 1.29

ASTM Activity index (Ia ASTM) 322

32

OAl3/2SiO

OAl3/1MgOCaO 1.26 1.04

Strength efficiency (H) 0.91 0.85

Proportion of glassy phase [%] ~ 60 ~ 85

7. We obtain more valid information about the fineness and specific surface of fly ash and

cements containing fly ash if we calculate this values from the particle size composition and

distribution using power function approaching (calculated specific surface).

I established connection between the Blaine specific surface determined by permeability method,

fineness number (x’) and calculated specific surface (Figure 13-14).


Viktória Gável


Figure 13. Connection between the Blaine

specific surface and fineness number (x‘) of

original and ground fly ash

Figure 14. Connection between the Blaine

and calculated specific surface of original

and ground fly ash

8. I documented the advantages of separated and combined grinding process in production of

cements containing fly ash with reduced clinker content. Grinding of the coarse fraction of fly

ash is sufficient to increase the pozzolanic activity of fly ash and thus to increase the strength of

cements containing fly ash.

8.1. I established that fly ashes used in the Hungarian cement industry generally have double

peaked, bimodal particle size composition (Figure 15), as well as the chemical composition of

‘fine’ (< 30 m) and ‘coarse’ (> 30 m) fractions is different, the ‘coarse’ (> 30 m) fraction

contains a higher amount of reactive SiO2 and CaO than the ‘fine’ fraction (< 30 m) (Table 6).

Figure 15. Particle size composition and

distribution of fly ash

Table 6. Blaine specific surface and

chemical composition of fly ash

‘Fine’

(< 30 m)

‘Coarse’

(> 30 m)

fraction

Blaine specific surface

[cm2/g]

14000 3600

Significant components [m/m%]

Loss on ignition 4.00 2.04

SiO2 35.19 50.27

Reactive SiO2 26.13 33.89

CaO 18.89 9.77

Reactive CaO 4.10 7.03

Al2O3 13.91 18.04


Viktória Gável


8.2. I proved that to increase the pozzolanic activity of fly ash grinding only the coarse particle is

sufficient. The pozzolanic activity of ‘coarse’ (> 30 m) fraction of fly ash is lower than activity

of the ‘fine’ (< 30 m) fraction, however the pozzolanic activity of fly ash can be increased by

increasing of fineness of ‘coarse’ (> 30 m) fraction by grinding (Figure 16).

Figure 16. Pozzolanic activity of original fly ash, ‚fine‘(< 30 m)

and ‚coarse‘(> 30 m) fractions of fly ash

8.3. I proved by experiments that the production of cement containing fly ash with reduced

clinker content and highest compressive strength can be implemented by the co-grinding of

clinker and the ‘coarse’ (> 30 m) fraction of fly ash and the subsequent mixing of the ‘fine’ (<

30 m) fraction of fly ash.

V. Opportunities for application

The results of dissertation can be utilized in the practice of cement industry and certain results

have already been utilized.

It can be demonstrated with the full knowledge of the connection between the grindability and

the influencing parameters that the change of grinding energy consumption of an industrial

clinker is traceable to the change of grindability of clinker or to the change of the work of

0

20

40

60

80

100

120

140

160

180

200

220

6500 3600 4250 14000

Po

zzo

lan

ic a

cti

vit

y:

Ca

Oa

bs

orb

ed

by

1 g

fly

as

h[m

g/g

]


Ori

gin

al

fly

as

h

Co

ars

e fra

cti

on

(>3

0m

)

Co

ars

e fra

c.

gro

un

d fo

r 1

0 m

in (

>3

0m

)

Fin

e fra

cti

on

(<

30

m)


Viktória Gável


grinding-separating system; whether the changes in production technology influence the clinker

grindability, necessary or not to revise the operation of mills. By certain changes in the

technology steps can be taken to produce easier grindable clinkers.

Since in one of the Hungarian cement plants the whole clinker production line was modernized

in 2007-2009 thus that cement plant was interested in complex investigation (chemical,

mineralogical composition, texture, grindability) of clinkers produced by the new production

line. During this research being in progress I annually perform the process and evaluation of data

of grinding tests of clinkers with special regard to certain technological changes in that cement

plant.

In case of plant production of cements containing fly ash with reduced clinker content the

grinding energy can be reduced by the application of combined (separated grinding + mixing)

grinding process recommended by me. It can be realized in the industrial practice that fly ash has

to be added into the air separator then the separated coarse fraction has to be run into the cement

mill and the fine fraction has to be added, more precise mixed to the cement. This conception is

suppoted by the experiences of the experiments carried out by the Institute of Raw Materials

Preparation and Environmental Processing and the Cemkut Ltd. in one of the Hungarian cement

plants in the frame of innovation research ‘Grinding technical researches to promote the

production of clinker saver and environmental friendly cement’.

The results of experiment have been applied since 2007 also in the frame of research project

‘Investigation of performance of portland-composite and composite cements containing high

amount, one or more type of cement additives; and the influencing quality and technological

parameters. In addition they establish the production of the so called CEM X type cements which

are cements with low clinker content to meet special quality requirements. Their properties

depend strongly on the quality and the amount added of the local cement additives. Elaboration

of technical prescription and the European standard is the task of Working Group WG6 of

CEMBUREAU CEN TC51. However the elaboration of real composition of these cements is

possible by taking into consideration of local conditions of the cement industry only.

The results of experiments can be applied from the point of view of environmental protection.

Because reducing the clinker content of cements produced contributes to decreasing of CO2-

emission of the cement industry.


Viktória Gável


In the course of my further research I am going to investigate the universal connections between

the composition, grinding fineness and quality of cements with reduced clinker content produced

by separate grinding. The actuality of my research in this field to continue is given by the

follows:

in one hand the engineering structures and thus the cements apllied to their production

have to meet more and more special requirements. It means that cement manufacturers

will have to produce market oriented cements with special composition to suit the

individual demands more often and the separate grinding + mixing technology is more

suitable for that;

on the other hand the new cement plant built in Hungary in 2011 has the technical

opportunities for realizing of separate grinding + mixing technology. However the

industrial application of this technology requires the performance and evaluation of a

large number of laboratory and industrial experiments.

VI. Literature

[1] Beke, B.: A cementipar néhány őrlési kérdéséről. Tudományos közlemények 33, Szilikátipari Központi Kutató

és Tervező Intézet (1969) Budapest

[2] Beke, B.: A finomőrlés folyamata (Kézirat). Budapesti Műszaki Egyetem Továbbképző Intézete, Budapest

(1975)

[3] Beke, B.: Aprításelmélet. Szilikátkémiai Monográfiák IV., Akadémiai Kiadó, Budapest (1963)

[4] Beke, B.: Őrlemények szemcseméret-eloszlásának egyenletességi tényezője. Műszaki Tudomány 44 (1971) pp. 83-96

[5] Opoczky Ludmilla: Cementőrlési folyamatok tanulmányozása és intenzifikálása felületaktív anyagok

alkalmazásával. Kandidátusi értekezés, Budapest 1968

[6] Opoczky, L. – Wojnárovitsné, H.I.: Klinkerőrlemény szemcséinek morfológiája és összetétele. Építőanyag

XXXV. (1983) 7. szám pp. 241-245

[7] Opoczky, L.: Mahltechnische und Qualitätsfragen bei der Herstellung von Kompositzementen. Zement-Kalk-

Gips 46 (1993) Nr.3, S.136-140

[8] Opoczky, L.: Possibilities for influence the particle size distribution in production of composite cements.

Európai Vegyészmérnöki Aprítási és Osztályozási Munkabizottság Egri ülésén (Comminution Conference)

elhangzott előadások különkiadványa. Miskolci Egyetem (1995), pp.1-18

[9] Opoczky, L. – Hilger, M.: Grinding technology and quality of composite cements. Proc. of the 10th Int. Congress on the Chem. of Cement (Göteborg, Sweden) Vol.1. (1997) 1i009 4pp

[10] Opoczky, L.: Grinding technical questions of producing composite cement. Int. J. of Miner. Processing 44-45

(1996) pp. 395-404

[11] M. Révay – F. Illés: Effect of the partial dispersity of the components on the properties of composite mixtures.

HUN-Pra-PARTEC Int. Conf. on Practical Aspects of Particle Technology, Proceedings pp. 141-146, Budapest

2001

[12] Mrákovitsné, T.K. – Verdes, S.: Őrlési problémák nagyszilárdságú cementek előállításánál. Építőanyag

XXXVIII. (1986) 9. szám pp. 257-261

[13] Sas, L.: Effect of coarse quartz and limestone grains on the properties of raw meal, clinker and cement. Proc.

of the 10th Int. Cong. on the Chemistry of Cement, Göteborg, Vol.1. (1997) 1i048 8pp

[14] G. Unland – K. Meltke – O. Popov – F. Silbermann: Assessment of the grindability of cement clinker. Part 2,

Cement International 2/2003 Vol. 1, pp. 54-63


Viktória Gável


[15] Hills, L.M.: Clinker Microstructure and Grindability: Updated Literature Review, Research & Development

Information, PCA R&D Serial No. 2967 (2007)

[16] Opoczky Ludmilla: A pernyék szilikátkémiai tulajdonságai. ”Tiszta környezetünkért” Szénerőműi pernyék

hasznosításával tudományos konferencián elhangzott előadás, A Miskolci Egyetem Közleménye A sorozat,

Bányászat, 55. kötet, (2001) p. 97-106, Egyetemi Kiadó, Miskolc 2001

[17] L. Opoczky – F.D. Tamás: Multicomponent Composite Cements. Advances in Cement Technology:

Chemistry, Manufacture and Testing (Editor: S.N. Gosh) pp. 559-594, Tech Books International, New Delhi

2002

[18] L. Opoczky – S. Verdes – K. Mrákovits Török: Grinding Technology for Producing High Strength Cement of

High Slag Content. 1. World Cong. Particle Technology, 6. European Symp. Comminution, Preprints pp. 281-

294, Nürnberg 1986 [19] Révay M. – Opoczky L.: A HCM Rt. által gyártott trassz- és kompozit portlandcementek néhány jellemző

tulajdonsága. Beton VII. évf. 1. szám 1999 pp. 3-7

[20] Csőke, B., Mucsi, G., Sík, Cs,: Production and practical application of mechanically activated fly ash-based

binding material. VIth Int. Conf. on Mechanochemistry and Mechanical Alloying, Jamshedpur, India 2008

[21] Csőke, B., Mucsi, G., Gál, A., Szabó, M.: Mechanical activation of lignite fly ash and brown coal fly ash and

their use as constituents in binders. Cement International No. 4/2009 Vol. 7, pp. 76-85

[22] Detwiler, R.J. – Bhatty, J.I. – Bhattacharja, S.: Supplementary Cementing Materials for Use in Blended

Cements. Research and Development Bulletin RD112T, Portland Cement Association, Skokie, Illinois, USA,

1996

[23] M. Öner: A study of intergrinding and separate grinding of blast furnace slag cement. Cement and Concrete

Research 30 (2000) 473-480 [24] Singh, N.B. – Middendorf, B.: Chemistry of blended Portland cements. Part 1: Natural pozzolanas, fly ashes

and granulated blastfurnace slags. Cement International, 4/2008, Vol. 6. pp. 76-88

[25] N.B. Singh – B. Middendorf: Chemistry of blended Portland cements. Part 2: silica fume, metakaolin, reactive

ash from agricultural wastes, inert materials and non-Portland blended cements. Cement International, 6/2009,

Vol. 7. pp. 78-90

[26] Djuric, M. – Ranogajec, J.: Mathematical Modelling in Cement Technology. Advances in Cement Technology:

Chemistry, Manufacture and Testing (Editor: S.N. Gosh) pp. 203-243, Tech Books International, New Delhi

2002

[27] Juhász, A. Z. - Opoczky, L.: Mechanical Activation of Minerals by Grinding. Akadémiai Kiadó - Ellis

Horwood Ltd Publishers.Budapest - Chichester 1990

[28] Z. Juhász – L. Opoczky: Mechano-Chemistry and Agglomeration. Progress in Mining and Oilfield Chemistry,

Vol. 5: Advances in Incremental Petroleum Production (Editor: I. Lakatos) pp. 405-412, Akadémiai Kiadó, Budapest 2003

VII. Publications in the topic of the PhD dissertation

Gável Viktória – Opoczky Ludmilla – Sas László: A technológiai paraméterek és a klinker

szövetszerkezete, valamint az őrölhetőség közötti összefüggés. Építőanyag 52 (2000) pp. 34-39.

Gável, Viktória – Opoczky, Ludmilla – Sas, László: Knowing clinker microstructure – a

possibility to influence grindability through technology. 22nd

International Conference on

Cement Microscopy (ICM) (2000) Montreal, Quebec pp. 215-225

Jankó András – Gável Viktória: Kivirágzási jelenségek a beton felületén. Beton VIII. évf. (2000)

7-8.sz. pp. 12-14.

Gável Viktória: A cementminőség szerepe betonadalékszer alkalmazásakor. Építőanyag 53

(2001) pp. 115-118.


Viktória Gável


Gável Viktória – Hatvani Zoltán: A nagynyomású hengermalom cementipari alkalmazásának

lehetőségei. Építőanyag 54 (2002) pp. 23-26.

Révay, M. – Gável, V.: Thaumasite Sulfate Attack at the Concrete Structures of the Ferenc

Puskás Stadium in Budapest. First International Conference on Thaumasite in Cementitious

Materials, BRE Garston 19-21 June 2002 (CD)

Opoczky, Ludmilla – Gável, Viktória: Effect of certain trace elements on the grindability of

cement clinkers in the connection with the use of wastes. 10th European Symposium on

Comminution, Heidelberg, 2nd-5th September 2002, p. 11 (CD)

L. Opoczky – V. Gavel: Effect of Certain Trace Elements on Grindability of Cement Clinkers

Connected with Use of WA. Focus on Remaining Oil and Gas Reserves,

Progress in Mining and Oilfield Chemistry, Vol. 4. Akadémiai Kiadó, Budapest 2002, pp. 295-

304

Opoczky Ludmilla – Gável Viktória: A különőrlés előnyei kompozitcementek előállításánál.

Építőanyag 55 (2003) pp. 2-7.

M. Révay – V. Gável: Thaumasite sulphate attack at the concrete structures of the Ferenc Puskás

stadium in Budapest. Cement & Concrete Composites 25 (2003) 1151-1155

L. Opoczky – V. Gável: Significance of the particle size distribution of cements with fly ash

admixture. PORANAL – 9th International Symposium on Particle Size Analysis, Environmental

Protection and Powder Technology, Balatonfüred 2004. szeptember 5-7. (CD)

L. Opoczky – V. Gavel: Effect of Certain Trace Elements on Grindability of Cement Clinkers

Connected with Use of WA. International Journal of Mineral Processing 74 (2004) S129-S136

Opoczky Ludmilla – Gável Viktória: A szemcseméret-eloszlás jelentősége pernyeadalékos

cementek előállításánál. Építőanyag 56 (2004) pp. 130-133.

Opoczky Ludmilla – Gável Viktória: Egyes nyomelemek hatása a cementklinker őrölhetőségére.

Építőanyag 57 (2005) pp. 5-10.

Gável, Viktória – Opoczky, Ludmilla – Sas, László: Correlations of grindability, chemical-

mineral composition and texture of cement clinker. 11th European Symposium on Comminution,

Budapest, 9-12 October 2006 (CD)

Csőke, Barnabás – Mucsi, Gábor – Opoczky, Ludmilla – Gável, Viktória: Modification of fly

ash properties by grinding. 11th European Symposium on Comminution, Budapest, 9-12 October

2006 (CD)


Viktória Gável


B. Csöke, Dipl.-G. Mucsi, L. Opoczky, V. Gável: Modifying the hydraulic activity of power

station fly ash by grinding. CEMENT INTERNATIONAL 06/2007 pp. 86-93

V. Gável, L. Opoczky, L. Sas: Investigation of the correlations between grindability, texture and

production parameters of cement clinkers. CEMENT INTERNATIONAL 5/2008 pp. 38-42

Ludmilla Opoczky and Viktória Gável: Manufacture of Low-Chromate Cements. World Cement,

February 2009 pp. 50-57

V. Güvel, L. Opoczky, L. Sas: Çimento Klinkerinde Öğütülebilirlik, Yüzen Dokusu ve Üretim

Parametreleri Arasindaki Bağıntının Araştırılması (Investigation of the Correlation Between the

Grindability, Texture and Production Parameters of Cement Clinker). Çimento ve Beton Dünyasi

(Cement and Concrete World), January February 2009 pp.62-71

Gável Viktória – Takács Enikő: Adalékszerek szerepe a betonok tartósságának alakulásában.

Beton XIX. évf. (2011) 3.sz. pp. 3, 22-24.

grinding theoretical and technological - midra

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