**8. Conclusion**

352 Material Recycling – Trends and Perspectives

Chromium (Cr) is used in different industrial field of applications such as steel industry, wood preservatives, electroplating, metal finishing, leather tanning, textiles and chemical manufacture and it is a frequent contaminant of both surface ground waters. In oxidizing conditions is highly soluble and forms Cr(VI) anions, such as chromates CrO42- or

reduction and a precipitation, Cr(VI) converts to Cr(III) that is insoluble. Both forms are stable in the environment. The roots plants can absorb both forms Cr3+ and CrO42-, but, according to some date, the Cr(III) forms stable compounds (e.g. hydroxides, oxides and sulphates). Therefore it is less soluble and, consequently, less bioavailable (Srivastava et al., 1994, as cited in Babula, P. et al., 2008). However Huffman et al. has shown as there are not uptake differences between Cr(III) and Cr(VI) by bean (*Phaseolus vulgaris, Fabaceae*) and

Although Cr is an essential element for animal and human health, hexavalent Cr salts have toxic and carcinogenic effects. The plant mechanism of toxic effect of Cr is due to the reaction between Cr-complexes and hydrogen peroxide that produces hydroxyl radicals. They can trigger off DNA alteration (Shi & Dalal, 1990a, b, as cited in Babula, P. et al., 2008),

Among heavy metals, steelmaking slags contain Vanadium (V). The V content in the processed ore is about less of 2%. During the blowing process into the LD converter the V is transferred to the converter slag as V2O5 (about 5%), which represents the main source for some procedures aiming to extract V from LD converter slag. Due to its heavy metals content and the environmental problems resulting to their release to earth, LD slag is often subjected to treatments, aiming to extract these harmful but also precious elements from it. Because of its physical properties, such as high tensile strength, hardness, and fatigue resistance, V is used in ferrous and non-ferrous alloys. For all these reasons it is desirable to

Among some studies about this topic, a recent research aims to investigate on the extraction procedure of V by using salt roasting and sulphuric acid leaching and how some leaching parameters, such as particle size, acid concentration, reaction temperature and solid:liquid ratio (S/L), may influence the kinetics process (Aarabi-Karasgani et al., 2010). The found optimum condition of leaching allows to achieve a maximum V recovery of 95%. Furthermore the size fraction of below of 0.850 mm has shown to be mostly effective in order to attain the maximum extraction. Two leaching stages have been proposed: the first one (the first 15 minutes), when the V leaching is faster, and a second stage (more than 30 min), when the leaching becomes slower. In addition, the leaching rate is controlled by chemical reaction at low temperature while at high temperature it is controlled by the solid

The increasing interest concerning the slags use for soil conditioning has focused the attention on the heavy metal concentrations in these materials. Several investigations carried out in Finland have shown that the concentration of some elements, such as Cr and Zn, are low because of the high temperatures of the processes. On the other hand, long-term experiments in Germany have shown that the application of steel slag as liming material does not increase the content of mobile chromium into the soil and, after using steelmaking slags as fertiliser, significant increases in Cr content have not been found in plants (R.

2-. Under reducing conditions, through a process involving a chemical

dichromates Cr2O7

wheat (*Triticum aestivum, Poaceae*).

recover this valuable element.

product diffusion.

Hiltunen & A. Hiltunen, 2004).

by affecting, for example, its replication and transcription.

The steel industry is committed to increasing the way for recycling slags generated during the steel production. Since their use as landfill material has almost reached its limit, the pressure for saving natural resources and energy has led steel industry, along with other important technological challenges, to improve and increase the recycling of this byproduct. While in the past steelmaking processes were exclusively design for the production of specific qualities of iron and steel, one of the today's goals for steelmakers is to design processes to produce high quality slags, according to the market requirements. New technologies and/or the improvement of existing technologies have been investigated and developed in order to achieve the ambitious target of "zero-waste" in the incoming years. To this aim, the effective utilisation of slags turns it into high value added product and allows to improve the steel industry competitiveness. On the other hand, the sustainable use of slags contributes to natural resources saving, to CO2 emission reductions and to consolidate a society founded on the recycling practice.

The use of steel slags in agriculture produces not only economic but also ecological advantages. A more effective exploitation of natural resources can be achieved in both the

Possible Uses of Steelmaking Slag in Agriculture: An Overview 355

Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008

Drissen, P., Ehrenberg, A., Kühn, M. & Mudersbach, D. (2009) Recent Development in Slag

EC (2001), Integrated Pollution Prevention and Control (IPPC) – Best Available Techniques

EC (2006), Commission of the European communities, regulation (EC) no 1907/2006 of the

EC (2009), Integrated Pollution Prevention and Control—Draft Reference Document on Best

Eloneva, S., Puheloinen, E.-M., Kanerva, J., Ekroos, A., Zevenhoven, R. & Fogelholm, C.-J.

Euroslag (2006) Legal Status of Slags. Position Paper. January 2006. The European Slag

Geiseler, J. (1996). Use of steelworks slag in Europe. *Waste management*, Vol. 16, No. 1-

Hiltunen, R. & Hiltunen, A. (2004). Environmental aspects of the utilization of steel industry

1–919783–58–X, The South African Institute of Mining and Metallurgy, 2004 Jamali, S. F. K., Forghani, A. & Shirinfekr, A.(2006).Effect of Steelmaking Slag and Converter

Kobesen, H. (2010). The registration of Ferrous Slags within REACH, *Proceeding of the 6th*

Kühn, M., Spiegel, H., Lopez, A. F, Rex, M. & Erdmann, R. (2006). Sustainable agriculture

Li, H.-J., Suito,H. & Tokuda, M.(1995).Thermodynamic Analysis of Slag Recycling Using a Slag Regenerator. *ISIJ Intenaltional*, Vol. 35, No. 9 (1995), pp.(1079-1088), ISSN 0915-1559 Motz , H. & Geiseler, J. (2001). Products of steel slags an opportunity to save natural

Negim, O., Eloifi, B., Mench, M., Bes, C., Gaste, H., Montelica-Heino, M. & Le Coustumer, P.

Treatment and Dust Recycling. steel research international, Vol. 80, No. 10,

Reference Document on the Production of Iron and Steel – December 2001,

European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation,Authorisation and Restriction of Chemicals(REACH), establishing a European Chemicals Agency, amending Directive 1999/45/EC and repealing Council Regulation (EEC) No 793/93 and Commission Regulation (EC) No 1488/94 as well as Council Directive 76/769/EEC and Commission Directives 91/155/EEC,93/67/EEC, 93/105/EC and 2000/21/EC,Available from: http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32006R1907:en:NOT

Available Techniques for the Production of Iron and Steel – July 2009, European

(2010). Co-utilisation of CO2 and steelmaking slags for production of pure CaCO3 legislative issues. Journal of Cleaner Production, Vol.18, No. 18, (2010), pp. (1833-

slags, *Proceedings of VII Intenational Conference on Molten Slags, Fluxes and Salts,* ISBN

Sludge on Some Properties of Acid Soil under Tea Planting, Proceeding of 18th World Congress of Soil Science, Philadelphia, Pennsylvania, USA, July 9-15, 2006 Kobesen, H. (2009). Legal Status of Slag Valorisation, *Proceeding of the First International Slag* 

using blast furnace and steel slags as liming agents, European Commission, ISBN

resources. Waste Management. Vol. 21, No. 3, (2001), pp. (285-293), ISSN 0956-053X

(2010). Effect of basic slag addition on soil properties, growth and leaf mineral

on waste and repealing certain Directives

European Commission, Brussels

Commission, Brussels

1839), ISSN 0959-6526

(October 2009), pp. (737-745), ISSN 1869-344X

Association - *EUROSLAG*. Duisburg, Germany

*Valorisation Symposium*, Leuven, Belgium, April 6-7, 2009

*Euroslag Conference,* Madrid, Spain, October 19-22, 2010

92-79-01702-0, Luxembourg, INTERNATIONAL

3,(1996), pp. (59-63), ISSN 0956-053X

steelmaking processes and in the agriculture. Obviously soil fertilisers have to supply nutrients, but should not have negative effects on the environment and on the human, animal and plant health. Therefore many studies have been particularly focused on the behavior and immobilization in the soil of the main heavy metals (e.g. Cr and V, contained in converter slag at higher concentrations), in order to achieve a more effective and sustainable use of steel slags in agriculture and thus improve its recycling.

#### **9. References**


steelmaking processes and in the agriculture. Obviously soil fertilisers have to supply nutrients, but should not have negative effects on the environment and on the human, animal and plant health. Therefore many studies have been particularly focused on the behavior and immobilization in the soil of the main heavy metals (e.g. Cr and V, contained in converter slag at higher concentrations), in order to achieve a more effective and

Aarabi-Karasgani, M., Rashchi, F., Mostoufi, N. & Vahidi, E. (2010). Leaching of vanadium

Abbaspour, A., Kalbasi, M., & Shariatmadari, H.. (2005). Effect of Steel Converter Sludge as

Ali, M.T. & Shahram, S.H. (2007). Converter slag as a liming agent in the amelioration of

Anderson, W.B. & Parkpian, P.(1984) Plant availability of an iron waste product utilized as

Babula, P., Adam, V., Opatrilova, R., Zehnalek, J., Havel, L. & Kizek, R. V. (2008).

Bialucha, R., Merkel, T. & Motz, H. (2011) European environmental policy and its influence

Bogdan, K., Schenk, M. K. (2009). Evaluation of soil characteristics potentially affecting

Branca, T.A., Colla, V. & Valentini, R. (2009). A way to reduce environmental impact of ladle

Conference of the Parties, 1997. Kyoto Protocol to the United Nations framework convention

Das, B., Prakash, S., Reddy, P.S.R. & Misra, V.N. (2007). An overview of utilization of slag

Dippenaar, R. Industrial uses of slag – The use and re-use of iron and steelmaking slags,

919783–58–X, The South African Institute of Mining and Metallurgy, 2004 Directive 2006/12/EC of the EuropeanParliament and of the Council of 5April2006 on waste

10 December, FCCC/CP/1997/L.7/Add.1, http:/www.unfccc.de.

Valorisation Symposium, Leuven, Belgium, April 18-20, 2011

157, No. 10, (2009), pp. (2617-2621), ISSN 2617-2621

from LD converter slag using sulfuric acid. Hydrometallurgy, Vol. 102, No. 1-4, pp.

Iron Fertilizer and Soil Amendment in Some Calcareous Soils. *Journal of Plant* 

acidic soils. International Journal of Agriculture and Biology, Vol. 9, No. 5, (2007),

an agricultural fertilizer on calcareous soil. *Journal of Plant Nutrition*, Vol.7, No.1,

Uncommon heavy metals, metalloids and their plant toxicity: a review. Environmental Chemistry Letters, Vol. 6, No. 4, pp. (189-213), ISSN 1610-3661 Besga, G., Pinto, M., Rodríguez, M., López, F. & Balcázar, N. (1996). Agronomic and

nutritional effects of Linz-Donawitz slag application to two pastures in Northern Spain. Nutrient Cycling in Agroecosystems, Vol. 46, No. 3, (1996), pp. (157-167),

on the use of slag products, Proceeding of the Second International Slag

arsenic concentration in paddy rice (Oryza sativa L.). Environmental Pollution, Vol.

furnace slag. *Ironmaking & Steelmaking*, Vol.36, No.8, (November 2009) , pp. (597-

on climate change. Report of the Conference of the Parties, Third Session, Kyoto, 1–

and sludge from steel industries. *Resources, conservation and Recycling,* Vol.50, No. 1,

*Proceedings of VII Intenational Conference on Molten Slags, Fluxes and Salts,* ISBN 1–

sustainable use of steel slags in agriculture and thus improve its recycling.

*Nutrition*, Vol. 27, No. 2, pp. (377 – 394), ISSN 0190-4167

**9. References** 

(14-21), ISSN 0304-386X

pp. (715-720), ISSN 1560-8530

pp.(223–233)

ISSN 1385-1314

602(6)), ISSN 0301-9233

(2007), pp. (40-57), ISSN 0921-3449


**15** 

*I.R. Iran* 

**From PET Waste to Novel Polyurethanes** 

It is well known that Poly (ethylene terephthalate) (PET) is a semi-crystalline thermoplastic polyester widely used in the manufacture of apparel fibers, disposable soft-drink bottles, photographic films, etc. The world production of PET in 2002 was 26 million tons which is expected to rise to 58 million ton in 2012 (Kloss J et al, 2006 & Shukla SR, 2009). The majority of the world's PET production is for synthetic fibers (in excess of 60%) with bottle production accounting for around 30% of global demand. The polyester industry makes up about 18% of world polymer production and is third after polyethylene (PE) and polypropylene (PP). Large numbers of post-consumer PET products, especially bottles and containers, do not create a direct hazard to the environment, but are being concerned due to their substantial volume fraction in the solid waste streams, their high resistance to the atmosphere, their poor biodegradability and photo degradability. Recently, recycling of PET has received a great deal of attention. Although the nontoxic nature, durability and crystal clear transparency of PET during use are major advantages, its non biodegradability is the serious cause of concern to the environmentalists. Since land filling of such non biodegradable waste has severe limitations, chemical recycling is the best possible alternative. Therefore, chemical recycling of PET leads to various advantages: consuming waste to get new useful materials and changing of a non- biodegradable polymer to a biodegradable one. Chemical recycling of PET includes chemolysis of the polyester with an excess of reactants such as water (hydrolysis) (Pusztaszeri SF, 1982, Mishra S et al, 2003; Schwartz J, 1995; Lamparter RA et al, 1985; Tindall GW et al, 1991 & Doerr ML, 1986) alcohols (alcoholysis), glycols (glycolysis) (Akiharu F et al,1986; Ostrowski HS,1975; . Güçlü G et al, 1998, Andrej K, 1998; Berti C et al, 2004; Manfred K et al,1993), amines (aminolysis) (Shukla SR et al,2006 ; Fabrycy E et al,2000;Zahn H et al,1963; Popoola V,1998) and ammonia (ammonolysis) (Blackmon KP et al,1990). Aminolysis has been little explored as chemical degradation of PET for synthesis of useful products. The use of ethanolamine for aminolytic degradation of PET waste has been investigated. (Shukla SR et al, 2006) The product obtained BHETA has potential for further reactions to synthesize useful products such as polyurethanes. There are few reports on the usage of recycled BHETA from PET to synthesis of polyurethanes. Depolymerization of the PET waste, using ethanolamine to obtain BHETA and BHETA-based polyurethanes, has been investigated in our works (Shamsi R et al, 2009; Mohammadi M et al, 2010; Mir Mohamad Sadeghi G et al, 2011). This

**1. Introduction** 

Gity Mir Mohamad Sadeghi and Mahsa Sayaf

*Dep. Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran,* 

composition of beans in a Cu-contaminated soil. Journal Soil and Sediment Contamination, Vol. 19, No. 2, (2010), pp. (174-187), ISSN 1532-0383

