Efecto de los residuos de flotación de cobre en el cemento

8/10/2019 Efecto de los residuos de flotacin de cobre en el cemento

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Introduction

With rapid growth of industrialization, there is pressure all over the world on available land, not

only for housing and industrial complexes, but for land-filling as a means of disposing huge

quantities of waste generated from industrial and mining-mineral processing operations [Rai et al.,

2002; Kula et al., 2001]. Disposal of industrial by-products in a hydrologic environment can cause

environmental risks due to the mobility of toxic trace elements.The main goals of environmentalprotection agencies and governments are to seek ways to minimize the dual problems of disposal

and health hazards of these by-products. The use of various types of waste materials as additives in

the production of cement and concrete has received substantial attention during recent years [Al-

Jabri et al., 2006; Penpolcharoen, 2005].

The copper flotation waste generated from the copper industry is generally disposed of without any

prior solid waste treatment in areas around the industrial facility where they are generated. Copper

flotation waste is classified as Hazardous waste according to current literature [Samet and

Chaaboni, 2004; Zain et al., 2004]. Landfill disposal of copper industry waste is not feasible since a

few hundred tones are produced per year per factory; leaching of heavy metals in the ground water

is of concern [Samet & Chaaboni, 2004; oruh & Ergun, 2006]. Dumping of such amount of

copper slags causes economic, environmental and space problems, therefore, currently governments

have implemented policies that give responsibility to mining and metallurgical companies for

reducing the volume of solid waste deposition by promoting the material recycling and reutilization

[Gordan, 2002; oruh et al., 2006]. Recent research papers reviewed the use of copper slag in the

production of value added products such as abrasive tools, abrasive materials, cutting tools, tiles,

glass, and roofing granules. They are also reported the potential use of copper slag as a partial

substitute of cement and aggregates in concrete and asphalt mixtures [Al-Jabri et al., 2006].

Investigations relating to the disposal of industrial by-products in cement have been actively

pursued. The disposal of these materials in cement conserves natural resources, energy, and reduces

pollution.

The present study includes the safe disposal of the copper flotation waste using as pozzolanic

material in cement production. In order to produce six group cement mixtures, copper flotation

waste is added in Portland cement clinker in the ratio of 2.5%, 5%, 7.5%, 10%, 12.5% and 15% due

to weight. Physical properties such as setting time, volume expansion and compressive strength

were determined and compared to reference mixture (PC 42.5) and Turkish standards (TSE, 2002).

Materials and Experimental Procedures

Materials

The copper flotation waste samples used in this study were obtained from the Eti Copper Works of

Samsun, Turkey. The cement was PC purchased from Yibita Cement Company, Samsun. This

cement is the most widely used one in the construction industry. The chemical compositions and

physical properties of cement, copper flotation waste are given Table 1. Copper flotation waste has

a black color and glassy appearance. SEM spectra in Fig. 1-a shows that copper flotation waste

consist mainly of magnetite (FeO.Fe2O3) and fayalite (2FeO.SiO2).


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Table 1.Chemical composition and physical properties of cement, copper flotation waste

Component Materials

Cement Copper flotation waste

Chemical composition (wt.%)

SiO2

Fe2O3*

Al2O3

TiO2CaO

CuO

ZnO

PbO

Cr2O3

CO2SO3

K2O

MgOBaO

CoO

Na2O

P2O5

MnO

LOI

Others

19.57

2.945.58

-

63.11

-

-

-

-

-

2.73

-

1.95-

-

-

-

-

3.35

0.77

24.87

67.680.88

-

0.69

0.98

2.78

0.21

-

-

2.18

0.48

0.360.10

0.21

-

-

0.12

-

-

* Iron oxides are presented as Fe2O3Loss on ignition

Figure1.Scanning electron microscopic (SEM) micrograph of copper flotation waste


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Mixtures Design

The binder material was mixed with copper flotation waste in definite ratio as given in Table 2.

Three series of mixtures and one reference mixture were prepared according to Turkish standards

(TSE, 2002). Reference mixtures were prepared out of Portland cement (PC) and reference as R.

The copper flotation waste mixtures were reference as CFW physical characteristics of mixtures are

shown in Table 2.

The mixtures of the specimens contained 450g cement, 1350g of fine aggregate and water liquid

/solid /L/S) ratio was 0.5.The cement-water mixtures were stirred at low speed for 30s then, with

the addition of sand, the mixtures were stirred for 5 min. eighteen batches were prepared and cast

into 40mm x 40mm x 160mm moulds for strength tests. After 24h of curing at 20oC with 95%

humidity, the samples were demoded and immersed in a tap water. Prepared materials were cured

for 2, 7, 28 and 90 days and were subjected to unconfined compressive strength testing [TSE,

2002].

Compressive strength measurement was tested with a Tony technique compression machine at the

loading rate 20-40 N/mm2/s according to TS 19. The setting times of mixtures were determinedaccording to TS 24 using a Vicatapparatus at room temperature [Gorai et al.,2003].

Table 2.Physical characteristics and composition of different cement mixtures

Symbol Cement mixes Fineness

+32 m

(wt.%)

+90 m

Specific

surface

(cm2/g)

Specific

gravity

(g/cm3)

R

CFW1

CFW2

CFW3CFW4

CFW5

CFW6

Reference mix

2.5% CFW+97.5% PC

5% CFW+95% PC

7.5% CFW+92.5% PC10% CFW+90% PC

12.5% CFW+87.5% PC

15% CFW+85% PC

13.5

15.6

16.7

15.415.5

13.1

13.9

0.1

0.2

0.3

0.20.4

0.1

0.5

3520

3400

3280

32903260

3200

3240

3.12

3.12

3.13

3.173.19

3.18

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Result and Discussion

Compressive Strength of Mixtures

Rate of strength development for six dosages of 2.5, 5, 7.5, 10, 12.5 and 15% copper flotation wasteused as Portland cement replacement were compared to reference mixtures for mortars. Mortar

cubes were tested for compressive strength after 2, 7, 28 and 90 days of curing. The trends of

compressive strength of mortar with copper flotation waste are shown in Fig. 2. At age of 2 days,

reference mixture showed the highest value (23.8 N/mm2) of compressive strength of the mixtures

tested. The mixture CFW2 showed close results to the reference mixture. The 2 days measured

compressive strength of mixture CFW6 has the lowest value of the compressive strength. This value

was obtained as 14.8 N/mm2. The 7 days measured compressive strength of mixture CFW1 was

close the mixture CFW2. These values were close to the 7 days measured compressive strength of

the reference mix. When curing extended to 28 days, an impressive increase in the performance of

the mixtures was noticed. The data indicate that the addition of small quantity of copper flotation

waste (i.e., 2.5%, 5%) has an important positive effect on cement strength. The addition of copperflotation waste (2.5 %) for compressive strength with 2, 7 and 28 days caused a reduction 12 %, 7.6

% and 3.7 % in the compressive strength of cement compared with the reference mixture. The 90


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day compressive strength compressive strength of CFW1 was close to the compressive strength of

the reference mixture.

The higher quantity of copper flotation waste showed an adverse effect on cement mixture. The

compressive strength of the mixture containing copper flotation waste decreased to a very

significant extent. This may be due to small pozzolanic contribution of copper flotation waste at this

age. It is well known that replacing cement by pozzolanic materials with low calcium would lowerthe early strength.

0

10

20

30

40

50

60

2 7 28 90

Age (days)

Compressivestrength(N/mm

2)

R CFW1 CFW2CFW3 CFW4 CFW5CFW6

Figure 2.Compressive strength of cement mixtures with copper flotation waste

Setting Time of Mixtures

The test results of the water percent and setting time of all mixtures are illustrated in Table 3. The

results clearly show in the Table 3 that all samples expect for CFW6 absorb less water than that of

the reference mixture. CFW6 mixture showed the higher absorption than reference and other

mixtures. It is proposed the high water absorption to the magnetic property of the copper flotation

waste. The magnetic property induces water to penetrate into the porosity, as well as to bind the

other surface of the samples, by the magnetic force [Mesci, 2007].

As seen from Table 3, setting times of reference and all mixtures are different. This difference may

arise from fineness and free CaO content of cement mixes.


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Table 3.Water percent and setting time test results for cement mixes

Cement mixes Water (%) Setting Time

Initial (min) Final (min)

R

CFW1

CFW2CFW3

CFW4

CFW5

CFW6

29.5

28.5

28.828.0

27.0

29.0

31.0

195

230

305280

300

300

440

260

295

365350

360

380

525

Conclusion

This paper presented the results of a research study on the effect of using copper flotation waste as apartial substitute for Portland cement in cement mixtures. A total of six mixtures were evaluated.

The results show that the performance of copper flotation waste cements is similar to that of more

traditional cement. At early ages, reference mixture showed higher strength than mixture containing

cement replacement material. At 28 and 90 days, the use of copper flotation waste even at the

concentration of % 2.5 and %5 showed a similar performance as the reference mixture. Higher

copper flotation waste (12.5%) replacement for cement resulted in adverse effects on cement

strength. This is expected since copper flotation waste has a low free lime content compared with

free lime in Portland cement. As a result 2.5% and 5% copper flotation waste can be used as

cementitious materials.

References

Al-Jabri, K.S., Taha, R.A., Al-Hasmi, A. & Al-harty, A.S. (2006): Effect of Copper Slag and

Cement by-Pass Dust Addition on Mechanical Properties of Concrete.

Construction and Building Materials 20, pp. 322-331.

oruh, S., and Ergun, O.N. (2006):Leaching Characteristics of Copper Flotation Waste Before and

After Vitrification.

Journal of Environmental Management 81, pp. 333-338.

oruh, S., Ergun, O.N., & Cheng, T.W. (2006): Treatment of Copper Industry Waste and

Production of Sintered Glass-Ceramic.

Waste Management and Research 3. pp. 234-242.

Gorai, B., Jana, R.K. & Premchand. (2003): Characteristic and Utilization of Copper Slag.

Resources, Conservation and Recyling, pp. 1-15.

Gordan, R.B. (2002): Production Residues in Copper Technology Cycles.Resources, Conservation

and Recyling 36, pp. 87-106.

Kula, I., Olgun, A., Erdogan, Y. & Sevinc, V. (2001): Effects of Colemanite Waste, Cool BottomAsh and Fly Ash on the Properties of Cement.

Cement and Concrete Research 31, pp.491-494.


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Mesci, B. (2007). Investigation of utilization possibilities of copper industry flotation waste and

zeolite in concrete production, Ph.D. Thesis, Civil Engineering Department, Ondokuz Mays

University, Samsun, Turkey.

Penpolcharoen, M. (2005): Utilization of Secondary Lead Slag as Construction Material.

Cement and Concrete Research, 35, pp. 1050-1055.

Rai, A., Prabakar, J., Raju, C.B. & Morchalle, R.K. (2002): Metallurgical Slag As a Component in

Blended Cement.

Construction and Building Materials 16, pp. 489-494.

Samet, B. and Chaabouni, M. (2004): Characterization of the Tunisian Blast-Furnace Slag and its

Application in the Formulation of a Cement.

Cement and Concrete Research 34, pp. 1153-1159.

Turkish National Standards, TSE 2002. imento-imento Deney Metodlar, Turkish Standard

Institute, Ankara, Turkey.

Zain, M.F.M., Islam, M.N., Radin, S.S. & Yap, S.G. (2004): Cement-Based Solidification for the

Safe Disposal of Blasted Copper Slag

Cement and Concrete Composites No.26, pp. 845-851.

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Efecto de los residuos de flotación de cobre en el cemento