THE POTENTIAL UTILIZATION OF SLAGS FROM THE
SECONDARY METALLURGY


Potenciální využití strusek z druhotné metalurgie

Václava Tomková1, Jan Melecký2, Lucie Drongová1, Jozef Vlček1
1VŠB-TU Ostrava, FMMI, Institute of Industrial Ceramics
2Mittal Steel Ostrava, a.s.

Abstract

Significant raw materials for potential utilization at geopolymer binders’ preparation are slags from steel production, in the first place ladle slag. According to the kind of produced steel the composition of these products in simplified system of main components comes under the two zones. Bigger part comprises slags with 15–40% SiO2 and 55–80% CaO, which show latent hydraulicity. With their activating by the water glass influence one gains binders of very good strength parameters. When combinating these slags with granulated blast furnace slag (GBFS) and fly ash (FA), can be modified not only the processability of mixtures, setting and hardening course but also the prise level of the products. Examples of strength development of specific raw materials mixtures from our region activated with water glass solution – silicate module SM = 2,0 and low Na2O dose are in the figure. These and other hardened masses show exceptionally good corrosion resistance in distilled water, acid and salt solutions. Experience gained from the cooperation ofIndustrial Ceramics Institute, VŠB-TU and Mittal Steel Ostrava, a.s. show the direction of utilization possibilities of large-tonnage secondary raw materials to ecologically and economically favourable preparation of alternative geopolymeric binders.


TUNGSTEN MINE WASTE GEOPOLYMERIC BINDER VERSUS ORDINARY PORTLAND CEMENT BASED CONCRETE. ABRASION AND ACID RESISTANCE

Geopolymerní pojivo z odpadů z dolování v Tungstenu v porovnání s betonem na bázi portlandského cementu. Odolnost vůči abrazi a kyselinám

Fernando Pacheco Torgal1, J.P. Castro-Gomes2, Said Jalali3
1Castelo Branco Polytechnic Institute, Portugal,
2University of Beira Interior, Portugal
3University of Minho, Portugal

Abstract. This paper reports results of a research project related to the development of geopolymeric binder using mineral waste mud from the Portuguese tungsten mine Panasqueira. Abrasion and acid resistance of two ordinary Portland cement (OPC) strength class concrete mixtures (C20/25 and C30/37) and several tungsten mine waste mud (TMWM) geopolymeric binder mixtures was evaluated. Acid resistance was performed by submitting samples to solutions of sulphuric acid, nitric acid and chloridric acid, results of weight loss are reported. Abrasion resistance was assessed by the mass loss of cubic specimens when submitted to 1000 rotations with the Los Angeles apparatus test machine. This study indicates that TMWM geopolymeric binders possess higher acid and abrasion resistance than OPC based concrete mixtures.

Keywords. Geopolymeric binder, tungsten mine waste mud, abrasion, acid, resistance


UNBURNING ALKALINE BINDERS AND HEAT-INSULATING

MATERIALS ON BASE OF RAW
OF CENTRAL ASIA REGION

Materiály na bázi surovin z centrální Asie

A.A. Tulaganov, Kh.Kh. Kamilov, M.K. Hasanova, P.V. Krivenko, H.B. Fischer, S.S. Kasimova, N.B. Khodzhaev, D.K. Tulaganov, Sh.Kh.Kamilov Building Materials - Science and Technology, Ltd Tashkent Architecture and Construction Institute

Kiev National University of Civil Engineering and Architecture Bauhaus-University, Weimar, Germany

Abstract. The possibility of the obtaining unburning alkaline binders on base of local raw and industrial wastes of the Central Asia region was investigated. The influence of water soluble substances, stalks of cotton plant on the properties of hydraulic binders, and contact zone between organic filler of vegetable origin with unburning alka­line and other binders was studied also.


ALKALINE BINDERS FOR REFRACTORY CONCRETES
ON THE BASIS OF SOLUBLE SILICATES AND
ALUMINATES OF SODIUM

Alkalická pojiva pro refrakční betony na bázi rozpustných silikátů a hlinitanů sodných

A.N. Yefremov

Donbass National Academy of Civil Engineering and Architecture, Makeyevka, Ukraine

Abstract. Alkaline binders of Na2O-Al2O3-SiO2-H2O, Na2O-MgO­SiO2-H2O, Na2O-MgO-Al2O3-H2O systems are developed on the ba­sis of water solutions of silicates and aluminates of sodium. Refrac­tory mineral materials are proposed as hardening (structure forming) components. It made possible to admix not more than 2% of oxide flux - Na2O to concrete and fact that does not influence on their limiting service temperature. The structure-phase changes of binder hardening products after heating at ordinary (20-110oC), average (800-900oC) and high (1200-1700oC) temperatures are studied by IR-spectroscopy, X-ray, DTA and chemical methods analyses. The influence of 2-6% Na2O on refractoriness and deformation tempera­ture indices under the load of aluminosilicate (30-95% Al2O3), mag­nesia (40-90% MgO) and magnesia-aluminate (95% MgO Al2O3) compositions are investigated. On the basis of these relationships recommendations are given how to proportion refractory concrete with maximum approximate fire properties of binders and aggre­gates. Contents of concrete is worked out, technological and service properties of aluminosilicate, magnesia and magnesia-aluminate re­fractory concrete - analogous of corresponding fired refractory bricks are studied.

Keywords. Alkaline binders, soluble silicates and aluminates of
sodium, refractory concrete


PROGRESS ON RESEARCH AND COMMERCIALISATION OF GEOPOLYMERS

Postup ve vývoji a rozptylu geopolymerů

Jannie S.J. van Deventer, John L. Provis, Catherine A. Rees, Chu Zheng Yong, Peter Duxson, Grant C. Lukey Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010, Australia

Abstract. The use of waste-based geopolymers can result in signifi­cant (up to 90%) reduction in carbon dioxide emissions when used in cement replacement applications. In addition to the formation of con­ventional pre-cast products, these high performance mineral binders are ideally suited to use in the conversion or encapsulation of toxic waste, including radioactive waste, due to their chemical stability and resistance to acid attack. It is the aim of this paper to review recent developments on the fundamental science underpinning this “green” process technology, and to discuss the technical and commercial drivers governing the large-scale adoption of the technology. Some of the recent fundamental breakthroughs in the study of geo­polymer technology at the University of Melbourne will be presented. The microstructural development and characteristics of geopolymers with varied nominal Si/Al ratio will be presented, indicating that labi­lity of species and the Si/Al ratio in the solution state play a large role in determining the final microstructure. These aspects of solution chemistry also control the rate of reaction. Despite the complexity of this reactive solid-gel system, progress has been made in the deve­lopment of advanced infared spectroscopic techniques for the analy­sis of reaction kinetics. Geopolymerisation is potentially a disruptive technology, so it is normal to expect strong resistance from established companies in the construction materials industry. Extensive demonstration of this technology is required before industry standards and practices will be changed. The strongest driver for this technology today is the growing pressure by governments and the public on companies to reduce carbon dioxide emissions. It is possible that this technology will be adopted first in newly industrialised countries instead of the developed world, and progress in this area will be discussed.

Keywords. Geopolymer, microstructure, nanostructure, ATR-FTIR


IMMOBILIZATION OF TOXIC CONTAMINANTS
INTO ALUMINOSILICATE MATRIXES

Imobilizace toxických látek do aluminoslikátové matrice

Hana Vinšová1, Věra Jedináková-Křížová1, Lukáš Grič2,
Josef Süssmilch2
1 Institute of Chemical Technology Prague
2Chemcomex Prague

Abstract

Alkali activated aluminosilicate matrix can be characterized by ability to bound certain cation into the structure of the matrix at the position of negative charge onto the aluminum atom. Cationic form of studied ele­ment are can be partially bound to the structure of polymeric chain. Thus the process is not only encapsulation of this element to the matrix. In this regard aluminosilicate matrix enables stabilization of water-soluble com­pounds with an increasing effectivity as against to Portland cement ma­trix.

The aim of this work was evaluation of retention capacity of alkaline activated aluminosilicated matrixes for the uptake of selected toxic ele­ments that are presented in the solidification product. Studied toxic ele­ments can be found as accompanying component at specific type of waste (predominantly different kinds of sludge). Ferric sludge coming from the treatment of technical water was used as major component of model waste.

A tested solidification products has been labeled with toxic elements (Pb, Cd, Cr, As) in two various forms - sparingly soluble compounds of toxic elements (elements as oxide) and second one were soluble forms (ionic form) of these elements. Different oxidation states of chromic com­pounds (e.g. CrO42-, Cr3+) were simultaneously applied for the study of retention ability of tested solidification products. Physical properties, hy­drolytic stability and leachability of toxic elements chemical forms into destiled water were used for the stability characterization of tested sam­ples.

Retention ability of aluminosilicate matrix is very selective process and depends on the occurrence of the individual chemical species of tested pollutant as it was shown for the immobilization of various oxida­tion states of chromic compounds. Due to the fact that solidification processes under the application of aluminosilicated matrix proceed in very strong basic environment, when chemical reactions could change chemical forms of toxic elements presented in the waste (e.g. change of insoluble As2O3 to soluble forms AsO2(OH)2-and AsO33-), it is very important to know the composition of individual species under the given conditions. The possible occurrences of chemical species of tested pol­lutants Eh and pH of aqueous environment were modeled. Geochemical computer code the Geochemist´s Workbench, which enable better explanation of immobilization mechanism has been used. Selected alu­minosilicate matrix provides excellent retention ability for Pb2+, Cd2+ and Cr3+ cations, while for arsenic and hexavalent chromium is poor.

Acknowledgements

This research was supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project MSM 6046137307 and project of Ministry of Industry and Trade No. MPO FI-IM/113.


EXPERIENCE FROM PRODUCTION AND APPLICATION OF THE SLAG ALKALINE CEMENTS AND CONCRETES

Zkušenosti z produkce a využití struskových alkalických cementů a betonů

Anatoliy Volovikov, Sergey Kosenko Joint Stock Company “Ilyich Iron and Steel Integrated Works”

Abstract. The paper covers previous experience obtained from commercial-scale production of the slag alkaline cement concretes in Mariupol in 1960- 1990s together with the results of current produc­tion at the Joint Stock Company “Ilyich Iron and Steel Integrated Works” in cooperation with the V.D.Glukhovsky State Scientific Re­search Institute for Binders and Materials. The problems on the way of commercial- scale production as well as ecological aspects (including waste-free technologies) are discussed in details.

Keywords. Alkaline activator, artificial stone, concrete, constituent composition, durability, granulated blastfurnace slag, optimization, plasticizer, slag alkaline cement, strength.

HIGH-STRENGTH FINE-GRAINED CONCRETES WITH MODIFIED MINERAL ADMIXTURES OF FLY ASH AND MILLED SLAG OF POWER STATION

Vysokopevnostní jemnozrnné betony s příměsí modifikovaných minerálií z úletových popílků a mletých strusek z elektráren

N.M. Zaichenko, A.K. Khalyushev, E.V. Sakhoshko

Donbass National Academy of Civil Engineering and Architecture, Makeyevka, Ukraine

Abstract. Increased demands to the physical-mechanical and operating properties of modern concretes stipulated the necessity of using the fine dispersed mineral admixtures in their compositions. In a combination with effective superplasticizers they contribute to concrete high strength and durability by pozzolanic (chemical) and filler (physical) effects as well as allow obtaining hi-tech concrete mixtures. Silica fume and amorphous metakaolin are the most widely used mineral admixtures in HPC technology. However, these materials are quite expensive. So this paper presents the results of determining the properties of high-strength fine-grained concrete mixtures and concretes containing dispersed pozzolanas of by-products of coal-fired electric power station – fly ash and milled slag. While the chemical composition of fly ash and slag is similar, XRD patterns indicated that the crystallinity of slag is much lower compared with fly ash. Incorporation of milled slag modified by SNF superplasticizer into high-strength fine-grained concrete as a partial cement replacement increases the long-term strength of concrete as well as its early one. Replacement of milled slag with fly ash of the same fineness results in considerable deceleration of concrete strength at an early age and insignificant decrease of the long-term strength of concrete. To eliminate this problem the sodium sulfate activator is used. This activator not only increases the early-age compressive concrete strength but also slightly improves the workability of concrete mixtures and decreases their slump loss. This is due to the concurrent adsorption of sodium sulfate and superplasticizer on the surface of cement and mineral admixture particles.

Keywords. Fly ash, milled boiler slag, compressive strength, workability, slump loss, adsorption, sodium sulfate activator


STRENGTH AND MICROSTRUCTURE DEVELOPMENT
OF ALKALI-ACTIVATED FLY ASH MORTARS

Vývoj pevnosti a mikrostruktury u alkalicky aktivovaných malt na bázi úletových popílků

Jelica Zelić1, Dražan Jozić1, Darko Tibljaš2

1Department of Inorganic Technology, Faculty of Chemical Technology, University of Split 2 Institute of Mineralogy and Petrology, Dept of Geology,
Faculty of Science, University of Zagreb

Abstract. The enhancing of pozzolanic activity of the fly ash, which emerges as the coal combustion by-product, by alkali activation is the critical key to large-scale application. By an alkali activation of fly ash, alkaline aluminosilicate polymers, referred as „geopolymers”, are formed. This new type of binder materials with empirical formula: Mn[-(Si-O2)z –Al-O2]n wH2O, where z is 1, 2 or 3; M is an alkali cation (Na or K) and n is the degree of polymerization, is characterized by a three-dimension amorphous network structures, and can exhibit superior chemical and mechanical properties compared to Portland cement-based materials. The present work reports preliminary results of the study on the products of reaction and strength development in an alkali-activated geopolymers material prepared using the Croatian Class F fly ash and sodium silicate solution (technical grade water glass, SiO2/Na2O = 3.1), and then thermally cured at 85 oC for different periods of time. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized in this study. The results of the investigation show that the main reaction product formed in the alkali-activated fly ash-based geopolymers is an amorphous alkaline alumino-silicate that induce a shift in the T – O (T = Si or Al) asymmetric stretching band towards lower wave number (1029 cm -1) related to ones in the original fly ash. It was found that mechanical strength of alkali-activated fly ash mortars are affected substantially by the duration of thermal activation and by the curing time, when the mortars cured for 24 h at temperature of 85oC had the highest compressive strength about 8 MPa at the age of 7 days, which then reached 15 MPa after 28 days of curing in the air at room temperature.

Keywords. Class F fly ash; Alkali activation; Geopolymers, Com-pressive strength, Mortars.

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