Recycling of Ornamental Stones Hazardous Wastes

doi:10.4236/nr.2011.24031

Paper Menu >>

Journal Menu >>

Natural Resources, 2011, 2, 244-249

doi:10.4236/nr.2011.24031 Published Online December 2011 (http://www.SciRP.org/journal/nr)

Recycling of Ornamental Stones Hazardous

Wastes

Abdel Monem Soltan, Zeinab Taman, Baher El-Kaliouby

Geology Department, Faculty of Science, Ain Shams University, Cairo, Egypt.

Email: abdelmonems[email protected]

Received September 11th, 2011; revised October 10th, 2011; accepted October 20th, 2011.

ABSTRACT

Sawing and polishing of the ornamental stones always generate large amount of solid and wet hazardous wastes, which

pollute the environment. In Shak Al-Thoaban area, East Cairo, Egypt, huge amounts of these wastes were accumulated,

during the last years, as rejects “Solid” and wet “Sahala” wastes, representing one of the main sources of environ-

mental pollution. The aim of this work is to characterize and evaluate these wastes for recycling in quicklime produc-

tion. Hence, samples of both wastes were investigated for their chemical and mineral composition applying XRF, XRD,

DTA and TGA methods. Free lime content and reactivity (RDIN) of both samples were also determined after calcination

for differnt soaking times (0.25 - 2.0 h) at 1000˚C. The results were interpreted in relation to composition and micro-

structure of the fired samples as revealed by TLM and SEM methods. The RDIN reactivity of the resulted lime is

changeable along soaking time at 1000˚C because of the microfabric of its crystallites. The lime of the “Solid” sample

is preserving the original limestone microstructure that contributes in its higher RDIN reactivity values at all soaking

times. The relatively higher degree of grain growth of lime crystallites in the “Sahala” sample leads to its lower reactiv-

ity. The optimum soaking times for the highest lime reactivity are 0.25 and 1 h for the “Solid” and “Sahala” samples,

respectively. On increasing soaking time up to 2 h, both samples show minimum RDIN values. The “Solid” sample also

gives higher free lime content than the “Sahala” one at all soaking times. It is gradually increased in the former sample

up to a maximum (96% - 97%) on increasing soaking time up to 1 - 2 h. On the other side, a maximum free lime (~95%)

is detected in “Sahala” sample at 0.25 h soaking time and gradually decreased to (87%) up to 2 h.

Keywords: Recycling, Ornamental Stones, Wastes, Microstructure, Quicklime

1. Introduction

Development of the ornamental stone industry in Egypt

is related to the expansion in the building and construc-

tion sector in the last three decades [1,2]. Most of the or-

namental stone factories are located in Shak Al-Thoaban

area, Katameya, East Cairo, Egypt.

The quarrying, sizing and polishing of the limestone,

granite, marble rocks among others are the main proce-

sses for ornamental stone production. Through these pro-

cesses 20% - 30% of the sawed blocks become fine pow-

der and solid-cutting rejects [3]. The solid-reject wastes

cause dangerous effects on the people working condi-

tions if stacked carelessly, however, the land filling is

costly and has serious drawbacks. Also, the fine powder

can cause serious health problems on inhalation and eco-

logical problems, when mixed with water and poured

into the natural water resources, such as rivers and chan-

nels [4,5].

Recycling of the ornamental stone wastes is the best

way for eliminating their hazardous impact on the people

and environment. This is encouraged by the fact that

these waste materials are mainly rock-derived with high

purity and can be consequently incorporated in different

industries [6].

Many possible applications were suggested to incur-

porate proportions of the wastes in the processing of tiles

[7-12], red ceramics [13-16], building materials [17],

mortars [18], concrete aggregates and mixtures [6,19]

and clay products [20,21].

According to the author’s knowledge, no research

works were directed to recycling of the solid rejects and

wet-powder “Sahala” wastes as a source of quicklime

after calcination. Therefore, this work directly aims at re-

cycling both of these ornamental stone wastes accumu-

lated in Shak Al-Thoaban area for production of reactive

quicklime. Hence, samples of both wastes were investi-

gated for their chemical and mineral composition apply-

Recycling of Ornamental Stones Hazardous Wastes245

ing XRF, XRD, DTA and TGA methods. Free lime con-

tent and reactivity (RDIN) of both samples were also de-

termined after calcination for different soaking times

(0.25 - 2.0 h) at 1000˚C. The results were interpreted in

relation to composition and microstructure of the fired

samples as revealed by TLM and SEM methods.

2. Sampling and Experimental Procedure

In Shak Al-Thoaban area, when the rock fine-powder is

mixed with water during sawing and polishing it trans-

forms into aqueous sludge called “Sahala”, whereas the

rejects of rock-cuttings is called “Solid” wastes and both

are disposed in the surrounding environment (Figures 1

and 2). Representative samples of both wastes were col-

lected and prepared through many field trips to the area.

The “Solid” sample was crushed into grains of 5 - 10

mm in diameter. The average mineral content of the two

samples was determined by conducting X-ray diffraction

analysis (XRD) using a Philips X-ray diffractometer

(Model PW/1840) with a Ni-Filtered, Cu-Kα radiation (λ

= 1.542 Å). The thermal behaviour was revealed by the-

rmal analysis, adopting a simultaneous recording of vari-

ations in heat content and weight by differential-thermal

Figure 1. “Solid” wastes of Shak Al-Thoaban.

Figure 2. “Sahala” wastes of Shak Al-Thoaban.

and thermo-gravimetric analyses (DTA and TGA) meth-

ods, respectively. The thermograms of both analyses are

recorded as a function of temperature, with a rate of heat-

ing of 10˚C/min, using Perkin Elmer, 7 series Thermal

Analysis System. The chemical composition was deter-

mined by X-ray fluorescence (XRF) using a spectrometer

(Model PW/1404) with Rh target and six analyzing crys-

tals. The petrographic characteristics of the “Solid” sam-

ple were examined using transmitted light (TLM) and

scanning electron microscopy (SEM).

Firing of the “Solid” and “Sahala” waste samples was

conducted by loading in alumina boats which calcined in

an electrical muffle furnace at 1000˚C for 0.25, 0.5, 1

and 2 h soaking times. After each firing, the calcined

samples were investigated for their microfabric by SEM

as well as free lime content and reactivity. The lime sam-

ples were dissolved in a sugary solution and titrated agai-

nst standardized HCl solution for determination of free-

lime content [22]. The lime reactivity was measured in

terms of the RDIN values [23], where the lime grains were

mixed with distilled water (1 lime: 4 water) in a calo-

rimeter. The time elapsed to attain a temperature of 60˚C

(T60 sec.) was measured and the RDIN was calculated

from the equation: RDIN = 2400/T60.

3. Results and Discussion

The XRD analysis showed that the main mineral content

of both of the “Solid” and “Sahala” waste samples is the

calcite (CaCO3) together with minor gypsum CaSO4·2H2O

in the “Sahala” sample. The DTA and TG curves (Figure

3) confirm the presence of calcite, where the its decom-

position commences at ~670˚C, 720˚C and ends at

~1000˚C with an average weight loss of 43.63% and

Figure 3. DTA and TGA of the waste samples.

Recycling of Ornamental Stones Hazardous Wastes

246

42.02% in the “Solid” and “Sahala” samples, respec-

tively [24]. The minor amount of gypsum detected by

XRD in the latter sample is confirmed by a small endo-

thermic peak at ~140˚C and a weight loss of ~1.2% due

to its dehydroxylation.

The chemical composition of the two waste samples

(Table 1) indicates highly pure material suitable for the

lime production [25]. The CaO average is 55.23%, where-

as the average of total impurity oxides (sum of silica, alu-

mina, magnesia as well as iron and alkali oxides) is

0.60%. Also, TLM-microstructure of the “Solid” sample

is showing the enrichment of fossils (grain-supported)

with prominent pores as exhibited in (Figure 4).

Figure 5 shows the trends of free lime content and

RDIN-reactivity of both the “Solid” and “Sahala” samples.

In the “Solid” lime samples the free lime content in-

creases with soaking time up to a maximum (~97%) at 1

h. and slightly decreases to (~96%) at 2 h. However, the

“Sahala” free lime is maximized at 0.25 h (~95%), then

gradually decreased to a minimum at 2 h (~87%). The

decrease in lime content is due to the possible belite for-

mation with the longer soaking time [26].

Both the “Solid” and “Sahala” lime samples are highly

reactive at all soaking conditions (RDIN > 30) as shown in

Figure 5. However, the “Solid” lime samples are more

reactive (RDIN = 57 - 97) than the “Sahala” ones (RDIN =

34 - 47). This is attributed to the relatively higher range

of free lime content of the former samples (95% - 97%)

as compared with that of the latter ones (87% - 95%).

Also, preservation of the original ghost pores (OGP) of

the parent limestone of the former samples as shown by

SEM (Figure 6(a)) has contributed in increasing the lime-

particles surface area and hence its reactivity [27].

The RDIN-reactivity values of both the “Solid” and “Sa-

hala” lime show a conspicuous decrease from 97 to 57 in

the former and from 47 to 34 in the latter by increasing

soaking time from 0.25 h to 2 h, respectively. This could

be attributed to the microfabric of the calcined lime as

exhibited in (Figures 6(b)-(d)). The “Solid” lime at 0.25

h is characterized by very small lime crystallites (less

than 2 μm) (Figure 6(b)), however their size is en-

larged to be more than (5 μm) at 2 h (Figure 6(c)). This

is due to the crystallite grain growth at the longer soaking

time [28,29].

On the other side, “Sahala” lime crystallites (Figure 6(d))

show grain growth micopores (GGM), which is the main

cause for its higher reactivity. However, at 2 h, the (GGM)

are closed due to the formation of lime holo- and hemihe-

dral-lime crystallites (HLC and HeLC, respectively) (Fig-

ure 6(e)), leading to lowering the reactivity of lime.

4. Conclusions

The “Solid” and “Sahala” ornamental stone wastes in

Shak Al-Thoaban, Egypt are hazardous materials for the

environment. Firing these wastes will eliminate their

hazardous impact together with production of a useful

Table 1. Chemical composition of the technological waste samples.

Sample CaO MgO SiO2 Al2O3 Fe2O3 TiO2 P2O5 MnO Na2OK

2O SO3 Cl L.O.I

Solid 55.61 0.11 0.160.03 0.11 <0.01 0.04 0.01 0.02 <0.01 < 0.01 0.03 43.70

Sahala 54.85 0.13 0.480.08 0.09 0.02 0.03 0.00 <0.01<0.01 1.05 <0.0143.09

Figure 5. Free lime and hydration behavior of the lime sample s.

Figure 4. Grain-supported limestone enriched with fossils.

Recycling of Ornamental Stones Hazardous Wastes247

Figure 6. SEM micrographs of the lime samples under different conditions (a) The preservation of the original pores of the

“Solid” lime at 0.25 and 2 h; (b) “Solid” lime at 0.25 h with remnant fossil pores; (c) “Solid” lime at 2 h; (d) “Sahala” lime at

1 h with GGM; (e) “Sahala” lime at 2 h with HeLC and HLC.

quick-lime product. The optimum firing conditions for

producing highly reactive lime for the “Solid” and “Sa-

hala” wastes are soaking for 0.25 and 1 h at 1000˚C, re-

spectively.

5. Acknowledgements

The authors are grateful to Ain Shams university, Egypt

for funding the research project: “Recycling of Shak Al-

Thoaban wastes”. The authors are also of deep gratitude

to all the persons working in Shak Al-Thoaban area of-

fered their sincere help, especially Haj Mahdy Abo-Zeid.

REFERENCES

[1] A. A. Dardir, A. K. Hassan and K. M. Abu Zeid, “Building

Recycling of Ornamental Stones Hazardous Wastes

248

and Construction Raw Materials in Egypt: An Overview,”

Proceeding of Geological Survey of Egypt. Cem. Confer-

ence, Cairo, 19-22 November1996, pp. 89-98.

[2] M. M. Hassaan, “The Economic Potential of the Mesozoic-

Cenozoic Carbonate Rocks in Egypt,” Sedimentology of

Egypt, Vol. 12, 2004, pp. 1-22.

[3] K. E. Alyamac and R. Ince, “A Preliminary Concrete Mix

Design for SCC with Marble Powders,” Construction and

Building Materials, Vol. 23, No. 3, 2009, pp. 1201-1210.

doi:10.1016/j.conbuildmat.2008.08.012

[4] G. Rego, C. Martínez, A. Quero, T. P. Blanco and J. M.

Borquea, “The Effects of Dust Inhalation in Slate Industry

Workers,” Medicina Clinica, Vol. 116, No. 8, 2001, pp.

290-291.

[5] A. S. Reis, “Estudo do Aproveitamento do Resíduo de Be-

neficiamento de Resíduo de Rochas Ornamentais na Fab-

ricac¸ ão de Ladrilho Hidráulico Piso Tátil,” Master Dis-

sertation, UFES-PPGEC, Vitória, 2008.

[6] H. Hebhoub, H. Aoun, M. Belachia, H. Houari and E. Gho-

rbel, “Use of Waste Marble Aggregates in Concrete,” Con-

struction and Building Materials, Vol. 23, No. 3, 2011, pp.

1167-1171. doi:10.1016/j.conbuildmat.2010.09.037

[7] S. N. Monteiro, L. A. Pecanha and C. M. F. Vieira, “Re-

formulation of Roofing Tiles Body with Addition of Gran-

ite Waste from Sawing Operations,” Journal of the Euro-

pean Ceramic Society, Vol. 24, No. 8, 2004, pp. 2349-

2356. doi:10.1016/S0955-2219(03)00638-1

[8] M. A. Monteiro, M. M. Jordan, M. B. Almendro-Candel, T.

Senfeliu and M. S. Hernández-Crespo, “The Use of a Cal-

cium Carbonate Residue from the Stone Industry in Manu-

facturing of Ceramic Tile Bodies,” Applied Clay Science,

Vol. 43, No. 2, 2009, pp. 186-189.

doi:10.1016/j.clay.2008.08.003

[9] P. Torres, H. R. Fernandes, S. Agathopoulus, D. U. Tulya-

ganov and J. M. F. Ferreira, “Incorporation of Granite Cut-

ting Sludge in Industrial Porcelain Tile Formulations,”

Journal of the European Ceramic Society, Vol. 24, No.

10-11, 2004, pp. 3177-3185.

doi:10.1016/j.jeurceramsoc.2003.10.039

[10] P. Torres, H. R. Fernandes, S. Olhero and J. M. F. Ferreira,

“Incorporation of Wastes from Granite Rock Cutting and

Polishing Industries to Produce Roof Tiles,” Journal of the

European Ceramic Society, Vol. 29, No. 1, 2009, pp. 23-

30. doi:10.1016/j.jeurceramsoc.2008.05.045

[11] A. J. Souza, B. C. A. Pinheiro and J. N. F. Holanda, “Proc-

essing of Floor Tiles Bearing Ornamental Rock-Cutting

Waste,” Journal of Materials Processing Technology, Vol.

210, No. 14, 2010, pp. 1898-1904.

doi:10.1016/j.jmatprotec.2010.07.001

[12] A. J. Souza, B. C. A. Pinheiro and J. N. F. Holanda,. “Re-

cycling of Gneiss Rock Waste in the Manufacture of Vitri-

fied Floor Tiles,” Journal of Environmental Management,

Vol. 91, No. 3, 2010, pp. 685-689.

doi:10.1016/j.jenvman.2009.09.032

[13] C. M. F. Vieira, T. M. Soares, R. Sánchez and S. N. Mon-

teiro, “Incorporation of Granite Waste in Red Ceramics,”

Materials Science and Engineering: A, Vol. 373, No. 1-2,

2004, pp. 115-121. doi:10.1016/j.msea.2003.12.038

[14] R. M. Romualdo, S. F. Heber, A. N. Gelmires, L. L. de

Helio and C. F. Heber, “Use of Granite Sawing Wastes in

the Production of Ceramic Bricks and Tiles,” Journal of

the European Ceramic Society, Vol. 25, No. 7, 2005, pp.

1149-1158. doi:10.1016/j.jeurceramsoc.2004.04.020

[15] A. Wilson, A. V. Francisco and M. S. Ana, “Using Orna-

mental Stone Cutting Rejects as Raw Materials for Red

Clay Ceramic Products: Properties and Microstructure De-

velopment,” Materials Science and Engineering: A, Vol.

435, 2006, pp. 327-332. doi:10.1016/j.msea.2006.07.091

[16] J. M. S. Moreira, J. P. V. T. Manhaes and J. N. F. Holanda,

“Processing of Red Ceramic Using Ornamental Rock

Powder Waste,” Journal of Materials Processing Tech-

nology, Vol. 196, No. 1-3, 2008, pp. 88-93.

doi:10.1016/j.jmatprotec.2007.05.008

[17] P. Asokan, S. Mohini and R. A. Shyam, “Solid Wastes Ge-

Neration in India and Their Recycling Potential in Building

Materials,” Building and Environment, Vol. 42, No. 6,

2007, pp. 2311-2320. doi:10.1016/j.buildenv.2006.04.015

[18] I. Mármol, P. Ballester, S. Cerro, G. Monros, J. Morales

and L. Sanchez, “Use of Granite Sludge Wastes for the

Production of Coloured Cement-Based Mortars,” Cement

and Concrete Composites, Vol. 32, No. 8, 2010, pp. 617-

622. doi:10.1016/j.cemconcomp.2010.06.003

[19] A. Nuno, B. Fernando and R. S. Jose, “Recycling of Stone

Slurry in Industrial Activities: Application to Concrete

Mixtures,” Building and Environment, Vol. 42, No. 2, 2007,

pp. 810-819. doi:10.1016/j.buildenv.2005.09.018

[20] A. M. Segadaesa, M. A. Carvalhob and W. Accharc, “Us-

ing Marble and Granite Rejects to Enhance the Processing

of Clay Products,” Applied Clay Science, Vol. 30, No. 1,

2005, pp. 42-52. doi:10.1016/j.clay.2005.03.004

[21] F. Saboya Jr., G. C. Xavier and J. Alexandre, “The Use of

the Powder Marble Byproduct to Enhance the Properties of

Brick Ceramic,” Construction and Building Materials, Vol.

21, No. 10, 2007, pp. 1950-1960.

doi:10.1016/j.conbuildmat.2006.05.029

[22] ASTM Standard C25-06, “Standard Test Methods for

Chemical Analysis of Limestone, Quicklime and Hydrated

Lime,” ASTM International, West Conshohocken, 2006.

[23] J. H. Potgieter, S. S. Potgieter, S. S. Moja and A. Mulaba-

Bfubiandi, “The Standard Reactivity Test as a Measure-

ment of Lime’s Quality,” Journal of the South African In-

stitute of Mining and Metallurgy, Vol. 102, No. 1, 2002, pp.

67-69.

[24] R. C. Mackenzie, “Differential Thermal Analysis,” Acade-

mic Press, London, Vol. 1, 1970.

[25] R. Boynton, “The Chemistry and Technology of Lime and

Limestone,” 2nd Edition, Wiley, New York, 1988.

[26] J. A. Oates, “Lime and Limestone: Chemistry and Tech-

nology, Production and Uses,” Wiley-VCH, Weinheim,

1998.

[27] H. Kainer, E. Specht and R. Jascher, “Pore Diffusion, Re-

action and Thermal Conduction Coefficients of Various

Limestones and Their Influence on Decomposition Time,”

Recycling of Ornamental Stones Hazardous Wastes

249

ZKG, Vol. 39, No. 5, 1986, pp. 259-268.

[28] W. D. Kingery, H. K. Bowen and D. R. Uhlmann, “Intro-

duction to Ceramics,” 2nd Edition, John Wiley and Sons,

New York, 1976.

[29] R. Gotthardt, W. Dornap and H. Wilder, “Effect of Lime-

stone Structure and Facies on the “R” Value as a Criterion

of the Degree of Burning,” ZKG International, Vol. 34, No.

8, 1981, pp. 424-429.