| 1. |
- Arm, Maria
(author)
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Self-cementing properties of crushed demolished concrete in unbound layers : results from triaxial tests and field tests
- 2001
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In: Waste Management. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0956-053X .- 1879-2456. ; 21:3, s. 235-239
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Journal article (peer-reviewed)abstract
- A 2-year study is underway to evaluate the expected growth in stiffness in layers of crushed concrete from demolished structures. This growth is said to be a result of self-cementing properties. The study consists of repeated load triaxial tests on manufactured specimens after different storing time together with falling weight deflectometer, FWD, measurements on test sections. Results so far show a clear increase with time in resilient modulus and in back-calculated layer modulus for all concrete materials. The increase is the largest in the first months and then diminishes. The field measurements show a more considerable growth in stiffness than the laboratory tests, with a doubled value two years after construction. Comparative investigations on natural aggregates, mostly crushed granite do not show any growth in stiffness, neither in the laboratory nor in the field. Consequences for the choice of design modulus are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Ecke, Holger
(author)
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Sequestration of metals in carbonated municipal solid waste incineration (MSWI) fly ash
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 631-640
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Journal article (peer-reviewed)abstract
- Waste management is in need of a reliable and economical treatment method for metals in fly ashes from municipal solid waste incineration (MSWI). However, no state-of-the-art technique has gained wide acceptance yet. This paper is a synthesis of five elsewhere published investigations covering a project which aimed to assess the possibilities and limitations of adding carbon dioxide (CO2) to fly ash as a stabilization method. Carbonation factors that were studied are the partial pressure of carbon dioxide (CO2), the addition of water, the temperature, and the reaction time. Laboratory experiments were performed applying methods such as factorial experimental design, thermal analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and leaching assays including pHstat titration and sequential extraction. Leaching data were verified and complemented using chemical equilibrium calculations. Data evaluation was performed by means of multivariate statistics such as multiple linear regression, principal component analysis (PCA), and partial least squares (PLS) modeling. It was found that carbonation is a good prospect for a stabilization technique especially with respect to the major pollutants lead (Pb) and zinc (Zn). Their mobility decreased with increasing factor levels. Dominating factors were the partial pressure of CO2 and the reaction time, while temperature and the addition of water were of minor influence. However, the treatment caused a mobilization of cadmium (Cd), requiring further research on possible countermeasures such as metal demobilization through enhanced silicate formation.
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| 3. |
- Jonsson, Susanne, 1965-, et al.
(author)
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Transformation of phthalates in young landfill cells
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 641-651
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Journal article (peer-reviewed)abstract
- Phthalic acid diesters are additives in a variety of materials that can end up in landfills. Leachates from a series of full-scale young landfill cells were analysed over time for dimethyl, diethyl, dibutyl, butylbenzyl, and di(2-ethylhexyl) phthalate (respectively designated DMP, DEP, DBP, BBP, and DEHP), and their corresponding monoesters monomethyl, monoethyl, monobutyl, monobenzyl, and mono(2-ethylhexyl) phthalate (MMP, MEP, MbutP, MbenzP, and MEHP, respectively), as well as o-phthalic acid (PA). One landfill cell was created in each of three consecutive years by deposition of the same type of waste in July and August. The pH, volatile fatty acids (VFAs), and total organic carbon (TOC) were measured to characterise development of the degradation phases in three landfill cells, which revealed early acidogenic to initial methanogenic stages. Analysis of the phthalate compounds showed that observed concentrations of the degradation products were below the detection limit in the acidogenic leachates but exceeded concentrations of their corresponding diesters in leachates from cells in the initial methanogenic phase. Maximum and average concentrations of phthalic acid were 50 and 23 mg/l, respectively, and the corresponding values for the other phthalates were 430 and 27 ╡g/l. The concentrations of all phthalates decreased during the establishment of stable methanogenic conditions. ⌐ 2003 Elsevier Ltd. All rights reserved.
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| 4. |
- Kylefors, Katarina, et al.
(author)
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A comparison of small scale pilot-scale and large-scale tests for predicting leaching behaviour of landfilled wastes
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:1, s. 45-59
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Journal article (peer-reviewed)abstract
- Landfills generate emissions over long periods, often longer than a lifetime. The longest lasting emission is leachate. In order to estimate the future requirements for leachate treatment, different kinds of leaching tests may be applied. In this paper, shaking leaching tests (SLT), landfill-simulator leaching tests and a field-cell leaching test performed with ash, municipal solid waste (MSW) and MSW+ash are evaluated. The tests are compared and the factors influencing leaching are identified and discussed. The factors are: liquid to solid (L/S) ratio, water withdrawal, recirculation rate, presence or absence of biological processes, size of particles, duration of experiment, temperature and pre-treatment of the waste. The presence of biological processes has the greatest impact on leaching and is the main reason why SLT is less useful for long-term predictions. The landfill simulator tests were found to be useful for several different kinds of predictions. However, they are not reliable for predicting the L/S required for reaching a certain concentration. The possibilities for reliable long-term predictions would be facilitated by a better knowledge of the influence of various factors on leaching. Such an increased knowledge would make it possible to enhance waste stabilisation in leaching tests as well as in full-scale landfills.
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| 5. |
- Lind, B.B., et al.
(author)
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Environmental impact of ferrochrome slag in road construction
- 2001
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In: Waste Management. - 0956-053X .- 1879-2456. ; 21:3, s. 255-264
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Conference paper (other academic/artistic)abstract
- Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analysed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials. Copyright (C) 2001 Elsevier Science Ltd.Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analyzed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials.
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| 6. |
- Macsik, Josef, et al.
(author)
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Leachability of V and Cr from LD-Slag/Portland cement stabilised sulphide soil
- 1996
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In: Waste Management. - 0956-053X .- 1879-2456. ; 16:8, s. 699-709
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Journal article (peer-reviewed)abstract
- The objectives of this study were to improve the mechanical stability of a sulphide soil with additives of an industrial waste product (LD-Slag) and Portland Cement. The criterion of using LD-Slag was if it could be done in an environmentally proper way. Sequential Leaching Tests were performed on monolithic LD-Slag/Portland Cement stabilised sulphide soil samples in order to register the leachability and pollution potentials. Different pH and Eh conditions were established in these tests in order to control the leachability of Na, K, Ca and Mg, which are important during cementation processes inside as well as outside an inforced monolith, and the leachability of V, which is regarded as a pollutant. The contents of Cr and V of pure LD-Slag, monolithic samples and leachates were compared with Canadian and Finnish Maximum Containment Level standards. The investigation showed that acidic conditions will increase the leachability of V. An acidic environment will even change the physical properties of a monolith. However, acidic conditions are not likely to occur in an in-situ anaerobic sulphide soil.
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| 7. |
- Menad, Nourreddine, et al.
(author)
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Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:6, s. 483-491
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Journal article (peer-reviewed)abstract
- Carbothermal treatment tests of electric arc furnace dusts (EAFD) using the Waelz kiln process were carried out in pilot-scale for the production of zinc oxide. The association of halides in the EAFD, and the recycled products, such as zinc oxide fumes and high-grade iron contents fractions were examined by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. XRD reveals the presence of chlorine and fluorine in the dusts in the form of KCl, NaCl and CaF2. An ultra-pure fraction of zinc was obtained after the Double Leaching Waelz Oxide (DLWO) process was performed on the zinc oxide fumes. The halide contents were reduced to approximately 100 ppm Cl and 700 ppm F. The rest of these elements are in the form of CaF2. About 65% F is volatilised as lead and zinc fluorides, 15% is expected in the magnetic fractions and 20% in non-magnetic fractions as CaF2 and MnF2, respectively.
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| 8. |
- Shen, Huiting, et al.
(author)
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An overview of recovery of metals from slags
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:10, s. 933-949
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Journal article (peer-reviewed)abstract
- Various slags are produced as by-products in metallurgical processes or as residues in incineration processes. According to the origins and the characteristics, the main slags can be classified into three categories, namely ferrous slag, non-ferrous slag and incineration slag. This paper analysed and summarised the generation, characteristics and application of various slags, and discussed the potential effects of the slags on the environment. On this basis, a review of a number of methods for recovery of metals from the slags was made. It can be seen that a large amount of slags is produced each year. They usually contain a quantity of valuable metals except for blast furnace slag and they are actually a secondary resource of metals. By applying mineral processing technologies, such as crushing, grinding, magnetic separation, eddy current separation, flotation and so on, leaching or roasting, it is possible to recover metals such as Fe, Cr, Cu, Al, Pb, Zn, Co, Ni, Nb, Ta, Au, and Ag etc. from the slags. Recovery of metals from the slags and utilisation of the slags are important not only for saving metal resources, but also for protecting the environment.
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| 9. |
- Singh, Maneesh, et al.
(author)
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Preparation of special cements from red mud
- 1996
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In: Waste Management. - 0956-053X .- 1879-2456. ; 16:8, s. 665-670
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Journal article (peer-reviewed)abstract
- Red mud from HINDALCO (Hindustan Aluminium Corporation) Industries Limited, Renukoot, India, contains significant quantities of alumina, iron oxide and silica. Presence of the said constituents makes it a suitable ingredient for the preparation of special cements. Preparation of three varieties of cements was investigated, namely: (a) aluminoferrite (C4AF)- belite (β-C2S) using lime + red mud + fly ash; (b) aluminoferrite-ferrite (C2F)-aluminates (C3A and C12A7) utilising lime + red mud + bauxite; and (c) sulfoaluminate (C4A3S̄)-aluminoferrite-ferrite using lime + red mud + bauxite + gypsum. The effects of composition (proportions of lime, red mud, fly ash, bauxite and gypsum), firing temperature and duration on the properties of cements produced were studied in detail. Cements made from lime + red mud + bauxite or lime + red mud + bauxite + gypsum exhibit strengths comparable or superior to ordinary Portland cement (OPC). On the other hand, those prepared using lime + red mud + fly ash did not have sufficient strength. Moreover, it was not possible to replace bauxite by fly ash (as a source of alumina) in any significant quantity.
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| 10. |
- Todorovic, Jelena, et al.
(author)
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Solidification with water as a treatment method for air pollution control residues
- 2003
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In: Waste Management. - 0956-053X .- 1879-2456. ; 23:7, s. 621-629
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Journal article (peer-reviewed)abstract
- The process of solidification with water was studied on air pollution control (APC) residues from incineration of refuse-derived fuel (RDF) regarding mechanical strength and leaching behaviour of solidified material. Factorial design in two levels was applied to investigate the impact of water addition, time, and temperature to mechanical strength of solidified material. Factors time and temperature, as well as the interaction between the addition of water and time significantly (α=0.05) influenced the mechanical strength of solidified material. The diffusion-leaching test NEN 7345 was performed to investigate if the leaching behaviour of elements from solidified material was determined by diffusion. Since it was found that leaching is not diffusion controlled, the long-term leaching behaviour was not assessed. However, the investigation showed that some of the studied components (Al, Hg, Mn, Pb, Si, and Zn) could be considerably demobilised by solidification with water. Concentrations of As, Cd, Co, Cu, Fe, and Ni were either below or not quite above the detection limits to be included in the analysis of leaching behaviour. The elements least demobilised by solidification were Cl, Cr, K, and Na.
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