Experimental Study of Mechanical Performance, Mill Output ...€¦ · shale on cement mill ou 2. Materials 2.1. Raw Materials The raw materials used for this work are presented •

European Journal of Scientific Research

ISSN 1450-216X / 1450-202X Vol. 156 No 3 May, 2020, pp.275 - 284

http://www. europeanjournalofscientificresearch.com

Experimental Study of Mechanical Performance, Mill

Output and Grindability of Portland Cement

Made with Calcareous Shale as Additive

Mambou Ngueyep Luc Leroy

Corresponding Author: Laboratory of Material Sciences

Department of Physics, Faculty of Sciences, University of Yaoundé 1

P.O.BOX 812 Yaoundé, Cameroon

School of Geology and Mining Engineering, University of Ngaoundéré

P.O. BOX 115 Meiganga, Cameroon

E-mail: [email protected]

Tel: + 237697419489

Keyangue Tchouata Jules Hermann



Tchapga Gnamsi Guy Molay

Laboratory of Material Sciences Department of Physics, Faculty of Sciences

University of Yaoundé 1 P.O.BOX 812 Yaoundé, Cameroon



Souaibou Fatoumata Adda



Ndjaka Jean-Marie Bienvenu

Laboratory of Material Sciences Department of Physics, Faculty of Sciences

University of Yaoundé 1 P.O.BOX 812 Yaoundé, Cameroon

Abstract

The present work deals with the valorization of calcareous shale rejected from

Bidzar quarry activities in CPJ35 cement production. The Lab tests performed with normal

limestone cement additive at 31%, used as our control sample compared to the addition of

calcareous shale at 31% and the mix limestone – calcareous shale at 29% and 5% in cement

respectively. Chemical composition and physico-mechanical analyses of these samples

show that the incorporation of 31% of calcareous shale could be an effective method for

valorization from both the environmental and economic points of view. Industrial trial with

the addition of calcareous shale cementitious at 29% confirmed an increase in mill output

of 3.4t/h for CPJ35.

Keywords: Limestone; Calcareous shale; grinding; mill output; cement Portland

Experimental Study of Mechanical Performance, Mill Output and Grindability of

Portland Cement Made with Calcareous Shale as Additive 276

1. Introduction For a few years, the technical community (standards committee, building and concrete companies,

engineering firms, contractors) have become aware of the need for rational and economical material

resource management. This naturally raises the issue of the appropriateness of using unusual material

sources, including industry co-product sand by-products, recycling materials and also some natural

materials. The substitution of "normal" cement materials (limestone, pozzolan well-known and used

for a long time) by these co-products and natural materials for cement production is often suggested as

a possibility [1-4]. However, such an act should not affect the quality or durability of buildings, road

construction. In this way, it should be performed at a controlled cost, and should not reduce the quality

performance on cement application. Grinding aids are mostly organic compounds that are added to the

clinker in the cement mill [5].

Their main purposes are to reduce the energy consumed in grinding the clinker. In addition to

increase the efficiency of the mill, some grinding aids can also provide important positive effects on

the final cement paste like the rheology and the improved strength development [5-7]. In cement mill,

the cement particles can coat the grinding media, seal the armour plating and agglomerate and form

small plates which absorb the impact. The cement particle agglomeration reduces the efficiency of the

mill. This phenomenon is characterized by an increase in energy consumption whilst maintaining

constant Blaine fineness [5].

In 2010 Assaad JJ et al.[6] evaluated the effect of grinding aids (GAs) on the percentage of

clinker decrease and reduction of energy needed during the grinding process.

Three GAs, based on amines, glycols and acids, were tested at various concentrations. The

tested cement properties include water demand, Blaine fineness, sieve residue, setting time and

compressive strength. The results showed that the use of higher concentrations of GAs can lead to

significant improvements in the performance of grinding mills characterized by higher Blaine and

lower sieve residue values. Compared with the control mix, setting times were found not to be

significantly affected. However, the mortar compressive strength increased by 15, 8 and 7% when

using GA based on amine, glycol and acid, respectively.

In 2013, Lai et al. [7] estimated production output, grindability/fineness, and strength-

enhancing effects of incorporating SikaGrinds874MY (SG) on ordinary Portland cement (OPC). In

projects I and II, OPC 42.5R was used, and sustainable cement (OPC+10% fly ash) was used in

project-III. Project-IV utilized OPC +26% fly ash +12% limestone. Conventional strength enhancer

(SE) was applied using the following proportions: 0.0%, 0.05%, 0.19%, and 0.1%. SG was used at

0.015%, 0.04%, 0.05%, and 0.035% by weight of cement in the four projects, respectively. Production

increased by 20.8%, 13.5%, 12.5%, and 10.5% by using SG. Blaine fineness considerably improved.

Moreover, the compressive strength of mortar was significantly enhanced because of the inclusion of

SG.

In 2015, Ebrahim Ghiasvand et al. [8] investigated the influence of the producing method

(inter-grinding and separate grinding) and particle size distribution (PSD) on early-age properties of

binary and ternary blended cements. Various experiments were carried out to determine properties of

cement paste including normal consistency, time of setting, heat of hydration and calcium hydroxide

content. In addition, compressive and flexural strength tests were carried out on cement mortars. Their

results shown that for achieving the same percentage of 45 μm residue in blended cements containing

Trass, inter-grinding was less energy demanding than separate grinding (shorter grinding time was

required).

In 2016 Toraman et al [9] studied the effects of liquid additives such as water, triethanolamine

(TEA) and ethylene glycol (EG) on the dry fine grinding of calcite by using a laboratory scale vertical

stirred mill. Their results showed that the chemical additives and water promoted the fine grinding of

calcite and that the maximum specific surface area of calcite (2.97 m2/g) was obtained with EG

additives 0.5%. The average particle size at this point was 3.16 μm.

277

In 2017,

pozzolanic materials for cement production. Inspired by the VTI method used in the coal industry,

which uses porcelain laboratory ball mill and compares

method was created. The first modification in methodology was the use of a planetary mill instead of a

porcelain drum mill. Another modification was in the measurement of undersize by means of laser

granulometry.

used for the comparison of properties.

In 2019, Ashem

Ordinary Portland Cement (OPC). Standa

times and compressive strength are tested for OPC. The phase composition and microstructure of the

formed hydrates are tested using DTA/TG and SEM techniques. Their results showed that both th

GAs had a significant improvement in the performance of grinding mills.

Few of these cited works investigated the possibility of the utilization of shale calcareous as

additive of cement Portland. In this work, we investigate the m

of Portland cement using

The paper is organized as follows.

Section 3 is devoted to

laboratory and industrial cement production incorporated with constituents. The Impact of calcareous

shale on cement mill ou

2. Materials2.1. Raw Materials

The raw materials used for this work are presented

• The clinker used, is manufactured from the Figuil plant

• Limestone

• Gypsum

• Calcareous shale

Tchapga Gnamsi Guy Mo

In 2017, K Dvo





granulometry. Their results were then used in the calculation of the grindability index, which can be


In 2019, Ashem







of Portland cement using


Section 3 is devoted to


shale on cement mill ou

Materials and Methods Materials

raw materials used for this work are presented

The clinker used, is manufactured from the Figuil plant

Limestone was

Gypsum was imported from Morocco,

Calcareous shale


K Dvořák and D Dolák





Their results were then used in the calculation of the grindability index, which can be


In 2019, Ashem et al. [11]







of Portland cement using calcareous


Section 3 is devoted to results of


shale on cement mill output is presented in section 4

Methods



was extracted from Bidzar quarry

imported from Morocco,

Calcareous shale was extracted fr

Figure 1:


Tchapga Gnamsi Guy Molay, Souaibou Fatoumata Adda

ák and D Dolák [10]







[11] used Triethanol amine and ethylene glycol as grinding aids for

Ordinary Portland Cement (OPC). Standard water of consistency, Blaine area, initial and final setting






calcareous shale as additive

The paper is organized as follows. Materials and method used

results of compressive test,


tput is presented in section 4



extracted from Bidzar quarry

imported from Morocco,

extracted from Bidzar quarry

1: a) Clinker, b) Limestone, c) Calcareous shale



investigated






used Triethanol amine and ethylene glycol as grinding aids for

rd water of consistency, Blaine area, initial and final setting






shale as additive

Materials and method used

compressive test, Chemical and physico


tput is presented in section 4. Finally,

raw materials used for this work are presented in Figure 1.


extracted from Bidzar quarry of Cameroon

om Bidzar quarry

a) Clinker, b) Limestone, c) Calcareous shale

Mambou Ngueyep Luc Leroy, Keyangue Tchouata Jules Hermann


investigated alternative evaluation of the grindability of


which uses porcelain laboratory ball mill and compares material based of oversize particles, a new










additive of cement Portland. In this work, we investigate the mechanical performa

Materials and method used

Chemical and physico


. Finally, conclusion is given in Section 5

Figure 1.

The clinker used, is manufactured from the Figuil plant of Cameroon

of Cameroon,

om Bidzar quarry Cameroon.



and Ndjaka Jean

alternative evaluation of the grindability of


material based of oversize particles, a new










echanical performa

Materials and method used are described in Section 2.

Chemical and physico-mechanical analyse


conclusion is given in Section 5

of Cameroon,

.















echanical performance and Grindability

are described in Section 2.

mechanical analyse


conclusion is given in Section 5

Keyangue Tchouata Jules Hermann,

Marie Bienvenu










formed hydrates are tested using DTA/TG and SEM techniques. Their results showed that both the two


nce and Grindability

are described in Section 2.

mechanical analyses of


conclusion is given in Section 5.

Experimental Study of

Portland Cement Made with Calcareous Shale as Additive

2.2.

grinded for the same time.

Table 1

3.Chemical analyses results of different raw materials are obtained with x

3.1. Characterization of

The results obtained from the X

calcareous shale vary as presented on Figure

Fe

proportion of these major elements SiO



2.2. Laboratory

• Lab Mill: 5 kg capacity

This protocol is aimed


• Trial 1; 65% clinker, 4% gypsum and 31% limestone,

• Trial 2; 65% clinker, 4% gypsum and 31% calcareous shale,

• Trial 3; 64% clinker, 3%

Table 1 illustrate

Table 1: Laboratory protocol of cement composition with calcareous shale and limestone

Trial

1 Clinker,limestone and gypsum

2 Clinker,calcareous shale and gypsum

3 Clinker,limestone, calcareous shale and gypsum

3. Results Chemical analyses results of different raw materials are obtained with x




The result

Fe2O3 (21.15%), Al




Laboratory Protocol of Cement Composition with Calcareous Shale and Limestone

Lab Mill: 5 kg capacity

This protocol is aimed


Trial 1; 65% clinker, 4% gypsum and 31% limestone,

Trial 2; 65% clinker, 4% gypsum and 31% calcareous shale,

Trial 3; 64% clinker, 3%

Table 1 illustrated

Laboratory protocol of cement composition with calcareous shale and limestone

Clinker,limestone and gypsum

Clinker,calcareous shale and gypsum

Clinker,limestone, calcareous shale and gypsum

Chemical analyses results of different raw materials are obtained with x




The results obtained, shows that the major elements in calcareous shale are SiO

1.15%), Al2O3


Mechanical Performance, Mill Output and Grindability of


Protocol of Cement Composition with Calcareous Shale and Limestone

Lab Mill: 5 kg capacity

This protocol is aimed to give

grinded for the same time. Therefore different compositions of trials were applied.



Trial 3; 64% clinker, 3% gypsum, 5% calcareous shale and 29% clinker.

d the cement compositions and grinding time.


Materials

Clinker,limestone and gypsum




3.1. Characterization of Calcareous Shale

The results obtained from the X-ray


Figure 2:

obtained, shows that the major elements in calcareous shale are SiO

3 (11.31%) and MgO (4.32%) respectively. Compare





e the cement composition with v

Therefore different compositions of trials were applied.



gypsum, 5% calcareous shale and 29% clinker.

the cement compositions and grinding time.





Calcareous Shale (X-ray

ray spectrometer showed that, the percentage of elements in

calcareous shale vary as presented on Figure 2.

Figure 2: Characterization of calcareous shale


(11.31%) and MgO (4.32%) respectively. Compare

proportion of these major elements SiO2, Fe2O3




the cement composition with v







Composition of 5kg sample

Clinker 3250g

Limestone 1550g

Gypsum 200g

Clinker 3250g

Calcareous shale 1550g

gypsum 200g


Clinker 3200g

Limestone 1450g


Gypsum 150g


ray Spectrometer

spectrometer showed that, the percentage of elements in

Characterization of calcareous shale



3 and Al2O3 are higher.



the cement composition with varying percentages of constituents,








Clinker 3250g

Limestone 1550g

Gypsum 200g

Clinker 3250g


gypsum 200g

Clinker 3200g

Limestone 1450g

careous shale 250g

Gypsum 150g

Chemical analyses results of different raw materials are obtained with x-ray fluorescence spectrometer

Spectrometer)





are higher. It is



arying percentages of constituents,





ray fluorescence spectrometer




(11.31%) and MgO (4.32%) respectively. Compared

It is also noticed an important



Grinding time

45min

45min

45min

ray fluorescence spectrometer


obtained, shows that the major elements in calcareous shale are SiO2 (25.02%)

to limestone, the

also noticed an important

278


Grinding time

45min

45min

45min

ray fluorescence spectrometer.


(25.02%),

to limestone, the

also noticed an important

279

proportion of MgO (4.32%). Generally, this element is below 3% in limestone

ignition of 13.41% and CaO (7.25%), lower than in limestone. This observation show

shale may resulted from the

shale can be used at a certain p


The X-ray fluorescence analysis was a qualitative and quantitative method giving the amount of each

oxide present in the sample; and the loss on ignition amount. The obtained results w

figure 3.

We

(uncombined state of CaCO

volatile CO

(2.02%), Al

P2O5 (0.08%)

crushing operations.

3.3. Chemical and

Production Incorporated

3.3.1. Compressive

The test is constructed in ac

compressive strength of mortar specimens. This mortar is formed from 1350g of standard sand, 450g

of cement and 225g of mixing water (W/C = 0.50). The essays are performed on the prismatic

specimens of 4 x 4 x 16cm which were packed in humidity cabinet at 20°C. After 24hours of time

mixing, these test pieces are remolded after being stored in water at 20±1°C until the burst test at 2, 7

and 28 days. The mechanical compressive strength is det

Carry out the test on halves of the prism broken with the flexural apparatus. Centre the prism

halves laterally to the platens of the machine within ± 0, 5 mm, and longitudinally such that the end

face of the prism

RC in mega




shale may resulted from the

shale can be used at a certain p

Characterization of

ray fluorescence analysis was a qualitative and quantitative method giving the amount of each


We can notice from the result obtained that 28.81% CaO, is the major element in limestone

(uncombined state of CaCO

volatile CO2 leaving from CaCO

(2.02%), Al2O3 (0.93%), Fe

(0.08%), Mn2O5

crushing operations.

Chemical and Physico


Compressive Strength Test

The test is constructed in ac








face of the prism overhangs the platens or auxiliary plates by about 10 mm.

in mega Pascals is read from the compressive press machine




shale may resulted from the metamorphism of granite. This statement makes us to think that calcareous

shale can be used at a certain proportion as constituent in cement.

Characterization of Limestone



Figure 3:

notice from the result obtained that 28.81% CaO, is the major element in limestone

(uncombined state of CaCO3). A high percentage of loss on ignition (41.07%) is a c

leaving from CaCO3

(0.93%), Fe2O3 (0.83%)

(0.02%) which might come from

Physico-Mechanical Analyses


Strength Test

The test is constructed in accordance to European standard








overhangs the platens or auxiliary plates by about 10 mm.

Pascals is read from the compressive press machine





metamorphism of granite. This statement makes us to think that calcareous

roportion as constituent in cement.

Limestone



Figure 3: Characterization of Limestone cementitious


). A high percentage of loss on ignition (41.07%) is a c

at high temperature (1150

(0.83%), SO3

(0.02%) which might come from

Mechanical Analyses

Production Incorporated with Constituents

Strength Test

cordance to European standard


















Characterization of Limestone cementitious



at high temperature (1150

3 (0.12%), Na

(0.02%) which might come from clay and soil, as pollutant during blasting and

Mechanical Analyses of Laboratory

Constituents

cordance to European standard





and 28 days. The mechanical compressive strength is determined on a compressive press apparatus.
















at high temperature (1150oc). We also obtained minor elements SiO

(0.12%), Na2O (0.05%), K

clay and soil, as pollutant during blasting and

Laboratory and

cordance to European standard [12-14]





ermined on a compressive press apparatus.




Pascals is read from the compressive press machine [12].


and Ndjaka Jean

proportion of MgO (4.32%). Generally, this element is below 3% in limestone and we had a loss on








c). We also obtained minor elements SiO

O (0.05%), K2O (0.05%), TiO


and Industrial Cement

14] and it consists to study the








overhangs the platens or auxiliary plates by about 10 mm. The compressive strength



and we had a loss on

ignition of 13.41% and CaO (7.25%), lower than in limestone. This observation shows that calcareous



oxide present in the sample; and the loss on ignition amount. The obtained results were depicted in


). A high percentage of loss on ignition (41.07%) is a consequence of

c). We also obtained minor elements SiO

O (0.05%), TiO2


Industrial Cement

and it consists to study the








The compressive strength


Marie Bienvenu

and we had a loss on

s that calcareous



ere depicted in


onsequence of

c). We also obtained minor elements SiO2

2 (0.09%),


and it consists to study the








The compressive strength



3.3.2.

The results obtained from these analyses are presented on Figure

limestone (12.64MPa), CPJ35 31% of calcareous shale (11.73 MPa) and CPJ35 29% of limestone +

5% of shale (11.84 MPa). All the values obtained are higher than the minimum limit value (10MPa)

stated in the national nor

calcareous shale (31.33MPa) are higher than the minimum value (30MPa) stated in the national norm,

wit

limestone + 5% of shale (28.04MPa) compressive strength is lower than the minimum limit value



3.3.2. Chemical and

Lab Test


Figure 5:

Concerning the compressive strength,



stated in the national nor

Similarly at 28 days strength, for CPJ35 31% of limestone (32.31MPa), CPJ35 31% of


with CPJ35 31% of limestone still being the highest.





Lab Test


Figure 5: Chemical and physico




stated in the national norm, with CPJ35 31% of limestone being the highest among the 02 others.



h CPJ35 31% of limestone still being the highest.




Physico-Mechanical Analysis


Chemical and physico-mechanical analysis of cement with different constituents from lab test




m, with CPJ35 31% of limestone being the highest among the 02 others.







Figure 4: Compressive test

Mechanical Analysis


mechanical analysis of cement with different constituents from lab test

Concerning the compressive strength, in figure 5, it










Compressive test

Mechanical Analysis of Cement



in figure 5, it






h CPJ35 31% of limestone still being the highest. It is



Compressive test

Cement with Different

The results obtained from these analyses are presented on Figure 5.


in figure 5, it is obtained at 02 days for CPJ35 31% of






It is noticed at 28 days CPJ35 with 29% of



Different Constituents


obtained at 02 days for CPJ35 31% of






noticed at 28 days CPJ35 with 29% of


Constituents from










280

from










281

(30MPa). The reason for this drastic drop is related to the total per

(29%+5%= 34%) which is higher than the 02 others CPJ35 (31%). We also observed a decrease in

strength with 31% of calcareous shale in CPJ 35 by (

31% limestone. The reason of this stren

high in CPJ35 with 31% of calcareous shale( 13.49%).This is because the unreactive silica content

%SiO2 (25.02%) is high and the value of CaO (7.28%) low in calcareous shale compare to CaO

(28.81%) in limestone.

CPJ35 31% of calcareous shale (0.93mm), CPJ35 29% of limestone + 5% of shale (2.00

respectively, and we noticed that these values do not exceed 10.00

Expansion is an important parameter used to consider a material as constituent in cement.

In addition, MgO for CPJ35 31% of limestone (2.56 %), CPJ35 31% of calcareous shale

(3.40%) and CPJ35 29% of limestone + 5% of shale (2.50%) are l

5% according to the national norm.

3.3.3. Chemical and

Shale

An industrial trial has been carried out with CPJ35 limestone and CPJ35

results on chemical and physico

Figure 6:

The results obta

The results on insoluble residue for CPJ35 calcareous shale1 (13.96%) and CPJ35 calcareous shale2

(13.22%) gave a high value compare to CPJ35 limestone (6.80%). The high inso

CPJ35 with calcareous shale are normally due to the high silica content in calcareous shale.

compressive strengths at 02 days of CPJ35 with calcareous shales (17.00MPa and 16.60MPa) are

almost equal to that of CPJ35 with limestone (16

CPJ35 with calcareous shale

with limestone (33.5MPa). However, the 02 samples of CPJ35 with calcareous shales are in

conforming to the minim

These chemical and physico

Bidzar quarry can be used as a constituent of cement.







(25.02%) is high and the value of CaO (7.28%) low in calcareous shale compare to CaO

.81%) in limestone.








Shale from Industrial Trial


results on chemical and physico

Chemical and physico

with calcareous shale

The results obta






CPJ35 with calcareous shale


conforming to the minim










.81%) in limestone. The results obtained on expansion are: CPJ35 31% of limestone (2.13







Physico-Mechanical Analysis

Industrial Trial


results on chemical and physico-mechanical analysis presented on Figure 6.

Chemical and physico-mechanical analysis from industrial trial of CPJ35 with limestone and CPJ35

with calcareous shale

The results obtained in figure 6






CPJ35 with calcareous shale (31.80MPa and 31.20MPa) have dropped by (


conforming to the minimum value at 28 days strength (30MPa








31% limestone. The reason of this strength reduction, is the impact of insoluble residue which is very



The results obtained on expansion are: CPJ35 31% of limestone (2.13







Mechanical Analysis

Industrial Trial


mechanical analysis presented on Figure 6.

mechanical analysis from industrial trial of CPJ35 with limestone and CPJ35

ined in figure 6 confirm the tendency of the results obtained from the lab tests.






(31.80MPa and 31.20MPa) have dropped by (


um value at 28 days strength (30MPa

These chemical and physico-mechanical analyses prove that the calcareous shale coming from






strength with 31% of calcareous shale in CPJ 35 by (- 1 MPa) at 02 and 28 days compared to CPJ35

gth reduction, is the impact of insoluble residue which is very









Mechanical Analysis of CPJ35 with




confirm the tendency of the results obtained from the lab tests.





almost equal to that of CPJ35 with limestone (16.90MPa). But at 28 days, compressive strengths



um value at 28 days strength (30MPa

mechanical analyses prove that the calcareous shale coming from






1 MPa) at 02 and 28 days compared to CPJ35









(3.40%) and CPJ35 29% of limestone + 5% of shale (2.50%) are lower than the maximum limit value

of CPJ35 with Limestone









.90MPa). But at 28 days, compressive strengths



um value at 28 days strength (30MPa) in the national norm NC 234.



and Ndjaka Jean

(30MPa). The reason for this drastic drop is related to the total percentage of material added








respectively, and we noticed that these values do not exceed 10.00 mm as s



ower than the maximum limit value

Limestone and CPJ35 with

An industrial trial has been carried out with CPJ35 limestone and CPJ35 calcareous shale. We obtained









(31.80MPa and 31.20MPa) have dropped by (-2MPa) compare to CPJ35


) in the national norm NC 234.




centage of material added








mm as stated in the norm.




and CPJ35 with

calcareous shale. We obtained




(13.22%) gave a high value compare to CPJ35 limestone (6.80%). The high insoluble residues in




2MPa) compare to CPJ35


) in the national norm NC 234.



Marie Bienvenu

centage of material added






The results obtained on expansion are: CPJ35 31% of limestone (2.13 mm),

CPJ35 31% of calcareous shale (0.93mm), CPJ35 29% of limestone + 5% of shale (2.00 mm)

tated in the norm.



and CPJ35 with

calcareous shale. We obtained




luble residues in

CPJ35 with calcareous shale are normally due to the high silica content in calcareous shale. The


.90MPa). But at 28 days, compressive strengths of

2MPa) compare to CPJ35





It is noticed that the values of expansion for CPJ35 limestone (0.10mm), CPJ35 calcareous

shale1 (0.10mm), and CPJ35 calcareous shale2 (0.10 mm) are lower than the maximum limit value (10

mm) stated by the national norm [15].

4. Reject and Mill Output of CPJ35 with Limestone and CPJ35 with Calcareous Shale

We ground different cement constituents using a lab mill of 5kg capacity and an industrial mill, we are

going to compare the grindability.

4.1. Grindability of Cement Made with Limestone and Cement with Calcareous Shale Lab Test

The results obtained from the grindability of cement with different constituents (limestone and

calcareous shale) in CPJ35, are presented on Figure 7.

Figure 7: Grindability of different cement composition

Figure 7 above shows the grindability of three different cement compositions. We obtained for

CPJ35 containing 31% of limestone, SSB (5646cm2/g), rejects(25.3%), CPJ35 containing 31% of

calcareous shale (6014cm2/g) SSB, reject (16.97%) and CPJ35 containing 29% of limestone + 5%

calcareous shale, SSB (5909cm2/g), rejects (25.74%). It is noticed that the SSB (specific blain surface

area) is higher and reject is lower with CPJ35 containing 31% of calcareous shale compare to CPJ35

containing 31% of limestone and CPJ35 containing 29% of limestone + 5% calcareous shale. This

statement is confirmed by a low calcareous shale density (2.15) compare to the two others CPJ35 with

limestone (3.00). This result shows that calcareous shale is easier to grind compare to limestone;

leading to an increase in mill output and consequently increases in volume of production.

4.2. Reject and Mill Output of CPJ35 with Limestone and CPJ35 with Calcareous Shale

In the previous lab tests results, we determined that CPJ35 with calcareous shale is easier to grind

compare to CPJ35 with limestone. The results obtained on Figure 8 show the impact of calcareous

shale on mill output and cement finesse.

283

Figure 8:

In figure 8 it is noted

compared

These values confirm the lab tests results; showing that calcareous shale is easier to

mill output has

The mill outputs of CPJ35 with calcareous shale obtained (25.71t/h and 26.96 t/h) are higher

than the mill output obtained with limestone (22.94 t/h). This industrial trial shows, a gain of 3 or 4 t/

in the cement mill is possible if we use calcareous shale. This gain may represent a good profit for

enterprise.

5. ConclusionThe characterization of calcareous shale showed us that the proportions of SiO

(11.31%), Fe

Al2O3 (0.93%), Fe

shale, showed a high insoluble residues (13.49%) coming from silica dioxide and a high MgO (3.40%

amount in cement.

the compressive strength tests performance. All the results obtained are lower than the maximum limit

value (10mm) as stated in the Cameroonian norm (NC

calcareous shale are easier to grind than regular limestone, this is showed by low rejects at 45

and a high SSB obtained. The impact of calcareous shale on grindability is seen on the increased mil

output with CPJ35 produced with calcareous shale (25.71t/h and 26.96t/h respectively) compare to

CPJ35 with limestone (22.94t/h). Calcareous shale can be valorized as a constituent in cement.


Figure 8: Reject at sieve 45 µm and mill output of CPJ35 with limestone and CPJ35 with calcareous shale

In figure 8 it is noted

to CPJ35 calcareous shale1 (8.17%) and CPJ35 calcareous shale2 (7.74%) respectively.


ll output has an important consequence of grindability.




enterprise.

Conclusion characterization of calcareous shale showed us that the proportions of SiO

(11.31%), Fe2O (21.15%) and

(0.93%), Fe2O (0.83%) and MgO (1.74%) respectively. The CPJ35 produced with calcareous


in cement. Meanwhile,

compressive strength tests performance. All the results obtained are lower than the maximum limit







Reject at sieve 45 µm and mill output of CPJ35 with limestone and CPJ35 with calcareous shale

In figure 8 it is noted that CPJ35 wit



an important consequence of grindability.




characterization of calcareous shale showed us that the proportions of SiO

O (21.15%) and MgO (4.32%) are higher than in regular limestoneusedSiO

O (0.83%) and MgO (1.74%) respectively. The CPJ35 produced with calcareous


Meanwhile, these high values do not have a significant impact on the expansion and










that CPJ35 wit








MgO (4.32%) are higher than in regular limestoneusedSiO



these high values do not have a significant impact on the expansion and










that CPJ35 with limestone had a high rejects at sieve 45 µm (9.13%)













value (10mm) as stated in the Cameroonian norm (NC 234). The lab and industrial tests confirmed that








h limestone had a high rejects at sieve 45 µm (9.13%)












234). The lab and industrial tests confirmed that






and Ndjaka Jean
























These values confirm the lab tests results; showing that calcareous shale is easier to grind. Generally,




characterization of calcareous shale showed us that the proportions of SiO2 (25.02%), Al

MgO (4.32%) are higher than in regular limestoneusedSiO2











Marie Bienvenu




grind. Generally,


than the mill output obtained with limestone (22.94 t/h). This industrial trial shows, a gain of 3 or 4 t/h


(25.02%), Al2O3

2 (2.02%),


shale, showed a high insoluble residues (13.49%) coming from silica dioxide and a high MgO (3.40%)




calcareous shale are easier to grind than regular limestone, this is showed by low rejects at 45 μm sieve

and a high SSB obtained. The impact of calcareous shale on grindability is seen on the increased mill





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