| 1. |
- Adolfsson, Daniel, et al.
(författare)
-
Hydraulic properties of sulphoaluminate belite cement based on steelmaking slags
- 2007
-
Ingår i: Advances in Cement Research. - : Thomas Telford Ltd.. - 0951-7197 .- 1751-7605. ; 19:3, s. 133-138
-
Tidskriftsartikel (refereegranskat)abstract
- Based on modified Bogue calculations, steelmaking slags were combined in order to produce a belite-rich clinker activated with sulphoaluminate. The experiments were conducted on two different mixtures based on steelmaking slags together with additives, namely MixA and MixB. The objective of the present study was to investigate the hydraulic properties of the specimens, using conduction calorimetry, X-ray diffraction and differential scanning calorimetry, and also to measure the mechanical strength of the specimens when hydrated for 2 and 28 days. The compressive strength was satisfactory in relation to the estimated compositions. Both mixtures behaved the same with regard to heat development as well as the amount of ettringite formed during the first 24 h of the hydration.
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| 2. |
- Adolfsson, Daniel, et al.
(författare)
-
Steelmaking slags as raw material for sulphoaluminate belite cement
- 2007
-
Ingår i: Advances in Cement Research. - : Thomas Telford Ltd.. - 0951-7197 .- 1751-7605. ; 19:4, s. 147-156
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, slags from the steelmaking industry are described and considered as a potential raw material within the field of sulphoaluminate belite cement. The objective of the study was to investigate the possibility of using a substantial amount of steelmaking slags as raw meal in the manufacture of a sulphobelitic clinker. A further aim was to compare the influence of different slags in relation to the formation of sulphoaluminate and the other clinker phases required. The behaviour of high temperature reactions was investigated by using thermogravimetric analysis coupled with a quadrupole mass spectrometer. Mineralogical observations were carried out through X-ray powder diffraction, and scanning electron microscopy. Three different mixtures and a single ladle slag were prepared using modified Bogue calculations, which are characterised by the assessment of a potential phase composition in order to produce belite-rich cement activated with sulphoaluminate. The results so far prove that steelmaking slags have the potential to be used as raw material, since sulphoaluminate along with polymorphs of dicalcium silicate and ferrite phases were detected after firing at 1200 degrees C in an air atmosphere.
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| 3. |
- Björkman, Bo, et al.
(författare)
-
Thermodynamic conditions for the reduction of dioxins during combustion of the organic parts contained in electronic wastes
- 1999
-
Ingår i: REWAS '99. ; , s. 937-648
-
Konferensbidrag (refereegranskat)abstract
- Electric and Electronic scrap contains about 30% plastics which are treated with halogenated flame retardants. During the combustion of these wastes, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. Their reduction can be performed by optimization of combustion parameters e.g. temperature in the combustion chamber, concentration of oxygen, temperature of flue gas at exit, residence time in the cooler, and HCl and H2O mixed in secondary air. The thermodynamic calculations show that, with an oxygen content of 0.1 mole, the total amount of dioxins/furans starts to reduce at 700°C and no formation of these isomers can be observed at 1000°C. However, these molecules are formed even at high temperature and the influence of chlorine on their reduction is negligible with an oxygen content of 1E-5 mole. On the other hand, the presence of SO2 in the gas mixture minimizes the dioxin emissions and the high concentration of water reduces the ratio of dioxins and furans in a given system
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| 4. |
- Cunha, Maria Lucelinda, et al.
(författare)
-
Leaching behaviour of industrial oxidic by-products : possibilities to use as neutralisation agent in bioleaching
- 2008
-
Ingår i: Advanced Materials Forum IV. - Stafa-Zurich : Trans Tech Publications Inc.. ; , s. 748-752
-
Konferensbidrag (refereegranskat)abstract
- In this study chemical leaching with sulphuric acid has been performed on 10 selected oxidic by-products in order to determine their neutralising capacity. The ultimate aim with this work is to replace the lime or limestone normally used in bioleaching operations to maintain pH at 1.5, the optimum pH-level for bioleaching microorganisms, with oxidic by-products. The investigated by-products includes three ashes from combustion for energy production, five slag samples from ore and scrap based steelmaking, an EAF dust and mesa lime from a paper and pulp industry, slaked lime (Ca(OH)2) was used as reference material. The neutralising potential of the by-products were evaluated by leaching them with sulphuric acid and comparing the amount of acid needed to that of the reference. Most of the by-products examined had good neutralisation potential and some had even higher capacities than Ca(OH)2. Neutralisation kinetics were lower for some slag products due to slow dissolution of some of the silicates present, but kinetics are considered good enough since stirred tank bioleaching is a relatively slow process. Zinc recoveries from the zinc containing materials were high, which thus is an additional benefit if these materials were to be used for neutralisation in a bioleaching process for zinc recovery.
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| 5. |
- Cunha, Maria Lucelinda, et al.
(författare)
-
Possibilities to use oxidic by-products for precipitation of Fe/As from leaching solutions for subsequent base metal recovery
- 2008
-
Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 21:1, s. 38-47
-
Tidskriftsartikel (refereegranskat)abstract
- In acidic biological and chemical leaching processes for base metal recovery, iron is dissolved in addition to the desired metal values. Prior to valuable metal extraction iron has to be removed. This is usually achieved through hydroxide precipitation of ferric iron by the addition of lime or limestone to a pH of approximately 3 whereby ferric hydroxide is formed. The aim of this work has been to investigate the possibility to substitute lime or limestone with oxidic industrial by-products for neutralisation and precipitation of iron from leaching solutions. The neutralisation potential for 10 selected oxidic by-products like slags, ashes and dusts were examined and compared with slaked lime.Experiments were performed by decreasing pH to 3 by additions of H2SO4 to slurry of respective by-product at an S/L ratio of 1/10 at 25 °C and continued till no changes in pH were observed during 10 days. Original samples, residues and solutions were analysed by ICP-MS and XRD in order to identify potential harmful elements for the subsequent metal recovery steps.Characterisation of the by-products revealed high concentrations of oxides such as lime, calcite and metal oxides as well as different forms of silicates in the materials which all dissolved at pH 3. The neutralising potential was found to be high for most of the by-products investigated and in the case of Ladle slag it was even higher than for slaked lime. Slags generally had higher neutralisation potential and long-term effects while the ashes had high initial reactivity which is important for continuous neutralisation in stirred tanks with limited retention times. The most reactive materials were Bioash and Mesa lime which both contained considerable amounts of calcite. Replacement of the conventional lime and limestone with oxidic by-products for neutralisation of acidic leaching solutions has the potential to save costs, environmental resources, reduce CO2 emissions and to recycle metal values like zinc contained in the by-products.
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| 6. |
- Ecke, Holger, et al.
(författare)
-
Carbonation of municipal solid waste incineration fly ash and the impact on metal mobility
- 2003
-
Ingår i: Journal of environmental engineering. - 0733-9372 .- 1943-7870. ; 129:5, s. 435-440
-
Tidskriftsartikel (refereegranskat)abstract
- Fly ash from municipal solid waste incineration (MSWI) is considered as hazardous waste that calls for a robust, reliable, and reasonable treatment technique. This investigation aims to assess the impact of CO2 partial pressure, water addition, time, and temperature on the stabilization of MSWI fly ash with particular emphasis on Pb, Zn, Cd, and Cr. Carbonation and element mobility were studied by applying thermal analysis and leaching assays on fly ash samples treated according to a 24 factorial design. The relationship between the factors and the response variables was evaluated using partial least squares modeling. Chemical equilibrium calculations were performed so as to complement the experimental findings. Decalcification of carbonated fly ash in a typical Swedish landfill was estimated at 0.13 mm.yr(-1) Treatment through carbonation reduced the availability of Pb and Zn about 100 times and also the carbonate alkalinity of 7.4 eq. (kg.FS)(-1) (FS represents the fixed solids) was remedied successfully. However, shortcomings that need to be resolved are the remobilization of Cr with time and the mobilization of Cd.
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| 7. |
- Ecke, Holger, et al.
(författare)
-
Treatment-oriented characterization of dry scrubber residue from municipal solid waste incineration
- 2002
-
Ingår i: Journal of Material Cycles and Waste Management. - 1438-4957 .- 1611-8227. ; 4:2, s. 117-126
-
Tidskriftsartikel (refereegranskat)abstract
- Dry scrubber residue from municipal solid waste incineration (MSWI) was characterized to identify critical inorganic pollutants and to suggest a conceptual treatment method. The key methods used were thermal analysis, including thermogravimetry (TG) and differential thermal analysis (DTA), pHstat titration, qualitative X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical equilibrium calculations, and statistics such as error propagation, principal component analysis (PCA), and empirical modeling based on factorial designs. Based on EU directives, the major inorganic pollutants Cd, Cr, Pb, and Zn were found. In addition, the pH was too high. With dry scrubber residue stabilization in mind, the impact of carbonation and hydration was assessed and judged to be encouraging. In particular, chemical equilibrium calculations showed that carbonation has considerable potential to lower the pH and the availability of Pb, Zn, and Cr. The impact of carbonation on the mobility of Cd was found to be small. During carbonation, a metal-trapping calcium aluminosilicate hydrate (C–A–S–H) phase is also formed. Both processes together have the potential to lead to a robust, reliable, and reasonable stabilization method for dry scrubber residue. However, to control these processes, the decisive factors need to be identified and their effects need to be quantified. Ca, Cl, Na, and K might be abundant components which would be mobile even after stabilization.
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| 8. |
- Forssberg, Eric, et al.
(författare)
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Metals recycling from electronic scrap by air table separation : theory and application
- 1998
-
Ingår i: EPD Congress 1998. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 0873393880 ; , s. 497-515
-
Konferensbidrag (refereegranskat)abstract
- Metals recovery from electronic scrap by physical separation may provide an alternative to the current recycling approach, through which halogenated flame retardants can result in hazardous dibenzo-p-dioxins and dibenzo-furans. On the basis of a complete sink-float analysis of personal computer and printed circuit board scrap, and in view of the advantages of dry processes for electronic scrap recycling by mechanical separation, air table separation is prioritized in an attempt to separate metals from plastics and glass involved. In the present paper, theoretical and practical considerations of air table separation have been detailed. It has been shown that air table separation is effective for recovering copper and precious metals from this specific waste stream. With the feed rate of 60 kg per hour, the combined grade and recovery of copper, gold, and silver attainable for the two heavy products produced by the air table used in the present study was shown in a table.
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| 9. |
- Kanari, N., et al.
(författare)
-
Chlorination of chalcopyrite concentrates
- 1999
-
Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 30B:4, s. 567-576
-
Tidskriftsartikel (refereegranskat)abstract
- The chlorination behaviors of two chalcopyrite concentrates and their pure constituents in Cl^sub 2^ + N^sub 2^ were investigated by thermogravimetric analysis (TGA) in nonisothermal conditions up to 1000 deg C. The effect of temperature on the reaction of chlorine with both concentrates was studied between 170 deg C and 300 deg C under isothermal conditions. The effects of gas flow rate, chlorine content of the gas mixture, and reaction time on the reaction rate were also investigated. The reaction products were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the kinetics of chlorination of chalcopyrite concentrates generating chlorides of Cu, Pb, Zn, Fe, and S was rapid at about 300 deg C. The iron and sulfur chlorides were volatilized, leading to a residue containing valuable metal chlorides.
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| 10. |
- Kanari, N., et al.
(författare)
-
Some aspects of the reactivity of olivine and serpentine towards different chlorinating gas mixtures
- 1998
-
Ingår i: Thermochimica Acta. - 0040-6031 .- 1872-762X. ; 319:1-2, s. 97-104
-
Tidskriftsartikel (refereegranskat)abstract
- The reactivities of olivine and serpentine towards mixture of chlorine in air, nitrogen and carbon monoxide were studied in non-isothermal conditions up to 1000°C. The samples were also chlorinated in a horizontal reactor over 2 h between 500° and 1000°C, under oxidizing and reducing atmospheres. The chlorination products were examined by XRD and SEM.The iron-bearing compounds contained in the natural olivine and serpentine samples can be eliminated through chlorination or oxychlorination of these solids at temperatures lower than 900°C. Carbochlorination of olivine and serpentine is incomplete even at 1000°C for a reaction time of 2 h. Pure magnesium chloride can be recovered by cooling the gas phase at ca. 500°C.
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| 11. |
- Lindblom, B, et al.
(författare)
-
Thermal decomposition of zinc hydroxo-carbonate obtained after leaching of EAF dust
- 2003
-
Ingår i: EPD Congress 2003. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 873395328 ; , s. 365-376
-
Konferensbidrag (refereegranskat)abstract
- An EAF dust generated in a Swedish steel mill has been leached in hydrochloric acid at pH = 3. The solution obtained has been subjected to purification by cementation followed by precipitation of zinc with sodium carbonate. The thermal decomposition of the precipitate was studied using thermal analysis and X-ray diffraction. The results show that during the calcination of the precipitate three different reactions occur. The decomposition of the solid phases Zn5(CO3)2(OH)6, CaZn(CO3)2 and CaCO3 occur completely at 370DGC, 560DGC and 940DGC respectively, yielding a final product containing 61.9% ZnO and 38.1% CaO. Methods to minimize calcium and manganese in the final product are discussed.
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| 12. |
- Menad, Nourreddine
(författare)
-
Auto shredder residue recycling
- 2005
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Ingår i: Proceedings of WasteEng 05. ; , s. D 60:1-D 60:12
-
Konferensbidrag (refereegranskat)
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| 13. |
- Menad, Nourreddine
(författare)
-
Cathode ray tube recycling
- 1999
-
Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 26:3-4, s. 143-154
-
Tidskriftsartikel (refereegranskat)abstract
- Lead and polybrominated flame retardants are the two hazardous materials that can be found in electronic appliances. Particularly, cathode ray tubes (CRT) contain leaded glasses. In a computer monitor, over 98% of the lead is in the CRT. This material is generally not accepted for reuse as a component; only those from televisions can be reused. However, this currently represents only a very small market. Envirocycle (a US company) has developed a process to recycle all glasses contained in CRTs; this process includes cleaning and sorting glass. The product obtained is used for the manufacture of new CRT glass. Some industries have used pulverized glass from CRTs in smelting processes as slagging material instead of sand or slag. In this paper, some environmental issues related to the recycling of computers and television sets, and CRTs from computers are presented and discussed. Different processes used to recycle CRTs are described along with an economic analysis.
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| 14. |
- Menad, Nourreddine, et al.
(författare)
-
Characteristics of electronic wastes
- 2000
-
Ingår i: EPD Congress 2000. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 873394593 ; , s. 231-243
-
Konferensbidrag (refereegranskat)abstract
- Electronic wastes are heterogeneous mixture, with mainly copper, aluminium and steel attached to or mixed with various types of plastics and ceramics. In general, small amounts of precious metals are incorporated in this mixture. Today, these components constitute an environmentally problematic fraction in disposal. Their physico-chemical characteristics have been investigated through chemical, x-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis.
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| 15. |
- Menad, Nourreddine, et al.
(författare)
-
Combustion of plastics contained in electric and electronic scrap
- 1998
-
Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 24:1, s. 65-85
-
Tidskriftsartikel (refereegranskat)abstract
- Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount up to 30% of the scrap mass. Generally, they contains flame retardants such as halogenated compounds which can lead to the formation of different toxic products. Recycling, incineration and landfilling are the current methods used to treat these plastics. They also can be used as combustibles in some metallurgical processes. However, during their combustion, halogenated flame retardants can produce dibenzop-dioxins and dibenzo-furans.
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| 16. |
- Menad, Nourreddine, et al.
(författare)
-
Minimization methods for emissions generated from sinter strands: a review
- 2006
-
Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 14:8, s. 740-747
-
Tidskriftsartikel (refereegranskat)abstract
- The agglomeration of iron ores or fine-grained recycled high-grade iron materials is an essential part of the integrated iron and steelmaking process. The 15 European countries produce more than 100 Mt of sinter per year. However, environmental regulation is becoming more stringent, and therefore, sintering plants are under pressure to minimize their generated emissions, because they are the most polluting processes. Different possibilities have been suggested to solve this problem, e.g. using imported pellets or briquettes in blast furnace or to use EAF process. Such changes are very expensive and also delete the recycling route of the by-products, thereby creating an additional treatment or disposal problem. In this paper, different methods for minimizing emissions generated from sinter strands are reviewed.
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| 17. |
- Menad, Nourreddine, et al.
(författare)
-
Oxidizing and reducing treatments of industrial hazardous wastes
- 1999
-
Ingår i: Toxicological & Environmental Chemistry. - : Informa UK Limited. - 0277-2248 .- 1029-0486. ; 70:3-4, s. 491-508
-
Tidskriftsartikel (refereegranskat)abstract
- Three samples generated by the non-ferrous metallurgy are subjected to thermal treatments between 200°C and 800°C in controlled oxidizing and reducing atmospheres. The objectives of these treatments are the elimination of toxic elements and the concentration of valuable metals in the treatments' residues. The treatments of these solids under oxidizing conditions at 700°C are well adapted for two samples. About 98% of toxic elements are eliminated and the totality of valuable elements is concentrated in the treatments' residues. The use of hydrogen at 600°C, permits the elimination of more than 96% of toxic elements and the recovery of up to 100% of valuable metals contained in the treated industrial wastes. The elimination rates of toxic elements (As, Hg, Cd, Se, ...) and the concentration rate of valuable metals (Pb, Zn, Cu) as well as the Global Decontamination Factor are reported.
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| 18. |
- Menad, Nourreddine, et al.
(författare)
-
Polyvinyl chloride used as a chlorinating and a reducing agent
- 1998
-
Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 24:3-4, s. 257-274
-
Tidskriftsartikel (refereegranskat)abstract
- Polyvinyl chloride (PVC) or vinyl is a recyclable material. It can be used as a chlorinating and a reducing agent. Two tests of chlorination and reduction of two different samples of jarosite and hematite were realized using PVC, results are presented in this paper. The chlorination test shows that the HCl gas produced from PVC and heated at ≈250°C can be used as a chlorine source to recover as chlorinated compounds the valuable metals such as Zn, Pb contained in jarosite. The XRD reveals the presence of lead and zinc chlorides in the condensates obtained. The second test of reduction was conducted using a mixture of PVC and hematite treated in a nitrogen atmosphere between 200 and 1000°C. The results show that at low temperature, PVC produces HCl and with kinetic consideration, no reactions can be observed with hematite. However, at high temperature, the weight of the hematite sample decreases by ≈15%, due to the reduction of hematite to iron metal.
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| 19. |
- Menad, Nourreddine, et al.
(författare)
-
Precursors for PCDD/F formation during combustion process
- 2000
-
Ingår i: EPD Congress 2000. - : Minerals, Metals & Materials Society. ; , s. 29-38
-
Konferensbidrag (refereegranskat)abstract
- The formation of the dioxins can be dependent on the quantities of carbon, hydrogen, chlorine and oxygen present in a given system, as well as on parameters such as temperature and pressure. Inadequate supply of combustion air (incomplete oxidation), low combustion temperatures (incomplete combustion), and insufficient turbulence in the combustion are factors which can favor their formation. Dioxins were produced also calatytically from chlorinated phenol precursors, non-chlorinated compounds that were chemically, and reaction of phenol with inorganic chloride. In this paper different precursors such as combination of C, H, O, Cl, rapid formation/combustion intermediates and routes to PCDFs are reviewed, and the influence of PVC amount on the formation of these isomers is discussed
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| 20. |
- Menad, Nourreddine
(författare)
-
Recycling of auto shredder residue
- 2007
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 139:3, s. 481-490
-
Tidskriftsartikel (refereegranskat)abstract
- Currently, about 75% of end-of-life vehicle's (ELV) total weight is recycled in EU countries. The remaining 25%, which is called auto shredder residues (ASR) or auto fluff, is disposed of as landfill because of its complexity. It is a major challenge to reduce this percentage of obsolete cars. The European draft directive states that by the year 2006, only 15% of the vehicle's weight can be disposed of at landfill sites and by 2015, this will be reduced to 5%. The draft directive states that a further 10% can be incinerated. The quantities of shredder fluff are likely to increase in the coming years. This is because of the growing number of cars being scrapped, coupled with the increase in the amount of plastics used in cars. In Sweden, some current projects are focusing on recycling of ASR material. In this paper some different alternatives for using this material are reported. The hypothetical injection of ASR into a blast furnace concentrating on ASR's effect to some blast furnace (BF) parameters has been completed using a blast furnace mass balance model. As a result, in principle, ASR can be used as reducing agent in the BF process if certain conditions are met. The particle size of ASR material must be controlled to ensure optimal gasification of the material in the raceway. Regarding the chemical composition of ASR, the non-ferrous content can affect the pig iron quality, which is difficult to rectify at a later point. The most attractive recycling alternative is to use the products obtained from pyrolysis of ASR in appropriate metallurgical processes.
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| 21. |
- Menad, Nourreddine, et al.
(författare)
-
Study of the presence of fluorine in the recycled fractions during carbothermal treatment of EAF dust
- 2003
-
Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 23:6, s. 483-491
-
Tidskriftsartikel (refereegranskat)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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| 22. |
- Menad, Nourreddine, et al.
(författare)
-
Thermal reduction of EAF dusts by using BF dusts as a reducing agent
- 2005
-
Ingår i: Proceedings of the REWAS '04. - : Minerals, Metals & Materials Society. - 8495520060 ; , s. 2751-2760
-
Konferensbidrag (refereegranskat)abstract
- The investigation of the thermal reduction of Electric Arc Furnace Dust (EAFD) by Blast Furnace Dust (BFD) was carried out using simultaneous thermogravimetric analysis (STA) coupled with Quadrupole Mass Spectroscopy (QMS). Chemical and mineralogical analyses were also employed. EAF Dust, which mainly consists of higher zinc compounds as Zincite (ZnO) and Franklinite (ZnFe2O4), is produced in electric arc furnaces (EAF). Blast furnace dust (BFD) with a carbon-iron rich, flue by-product released in the iron-making process was used as a reductant agent. Both raw materials were examined individually in different controlled atmospheres of Ar, air and CO 2 between 20° and 1400°C. Different parameters such as effect of reaction atmosphere, temperature and quantity of the reductant agent were explored. The products of reaction were examined by x-ray diffraction (XRD) as well as the gaseous substances evolved in the reactions. The results indicated that, at 1300°C in Ar atmosphere, a complete reduction of oxide compounds contained in both samples is achieved with a 33 % reductant mixture
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| 23. |
- Menad, Nourreddine, et al.
(författare)
-
Thermal treatment of dusts from non ferrous metallurgical industries
- 2000
-
Ingår i: Revista de metalurgia. - : Editorial CSIC. - 0034-8570 .- 1988-4222. ; 36:3, s. 159-164
-
Tidskriftsartikel (refereegranskat)abstract
- Three samples of dusts generated by the non ferrous metallurgical industries are treated between 200 and 800 °C in controlled oxidizing and reducing atmospheres. The objective of this study is to recover the valuable metals from these wastes. The treatments of these solids under oxidizing conditions at 700° are well adapted for two samples. The totality of valuable elements are concentrated in the treatments' residues. The use of hydrogen at 600° C, permits the removal of up to 100% of valuable metals contained in the treated industrial wastes. The recovery rate of valuable metals (Pb, Zn, Cu) as well as the Global Decontamination Factor are reported.
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| 24. |
- Menad, Nourreddine, et al.
(författare)
-
Thermal treatments of industrial wastes in controlled atmospheres for the elimination of As, Hg, Cd, Se and the concentration of Pb, Cu and Zn
- 1999
-
Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 25:3-4, s. 233-254
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal treatments of five different types of non-ferrous metallurgical wastes, under a controlled atmosphere, were carried out at temperatures lower than 800°C for the separation of their toxic compounds and the concentration of valuable metals in the treatments residues. The best results were obtained by the treatments in air or hydrogen, or both successively. Simple treatments, using air or hydrogen, of three samples allowed the elimination of more than 95% of their toxic elements and almost doubled their valuable metals concentration. For the rest of the samples, a combined treatment was necessary for their efficient decontamination. In this case, the valuable metals content in the treatment's residue was increased to a reasonable value. Most of the solids issuing from these treatments can be recycled in current non-ferrous metallurgical processes.
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| 25. |
- Menad, Nourreddine, et al.
(författare)
-
Thermodynamic conditions for the formation of dioxin during the recycling of non ferrous metals from electric and electronic scrap
- 1998
-
Ingår i: EPD Congress 1998. - Warrendale, Pa. : Minerals, Metals & Materials Society. - 0873393880 ; , s. 657-673
-
Konferensbidrag (refereegranskat)abstract
- Plastic materials have been associated with electric and electronic applications since the early days of the electrical industry. Plastics can amount to 30 percents of the scrap mass. Generally, they are treated with flame retardants such as halogenated ones and they can result in different toxic chemical compounds. These plastics can be used as combustibles in the recovery of copper and precious metals. However, during their combustion, halogenated flame retardants can produce dibenzo-p-dioxins and dibenzo-furans. The estimated thermodynamic data of several organic compounds resulting from combustion of electric and electronic scrap, have been used in conjunction with the program HSC to calculate the conditions for dioxin and furan formation. The results show that the formation of the dioxins is dependent on the quantities of carbon, hydrogen, chlorine and oxygen reacting in a given system, as well as on parameters such as temperature and pressure.
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| 26. |
- Pineau, J.L., et al.
(författare)
-
Representativeness of an automobile shredder residue sample for a verification analysis
- 2005
-
Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 25:7, s. 737-746
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Tidskriftsartikel (refereegranskat)abstract
- To apply a decision-making scheme using a statistical classification while conforming to the meaning of representativeness as defined by the US EPA, we propose an equation defining the representativeness of a sample. To utilize this equation, the batch must be homogenized. This requires analyzing the constitution and distribution heterogeneities. The equation relates the sample weight ms to its representativeness R either by a statistical approach or by a physical approach using the following equation:ms={4/(1-R)2}·[K+ke(1-2te)/te] In the equation, K and ke are the heterogeneity factors determined from a descriptive analysis. This equation is applicable to solid waste with majority constituents such as automobile shredder residue (ASR) and domestic waste. This analysis was applied to a sample of ASR in the framework of a verification for France. The results of the analysis showed that the sample weight must be at least 140 kg to have a representativeness of 90%.
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| 27. |
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| 28. |
- Sandström, Åke, et al.
(författare)
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EAF dust processing with a combination of hydro- and pyrometallurgical techniques
- 2003
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Ingår i: EPD Congress 2003. - : Minerals, Metals & Materials Society. - 873395328 ; , s. 377-388
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Konferensbidrag (refereegranskat)abstract
- An EAF dust sample generated in a scrap based steel mill was treated by a combination of hydro- and pyrometallurgical techniques. The EAF dust contained mainly ferritic spinels forming solid solution phases according to the general chemical formula (MnxZnyFe1-x-y)Fe2O4 and other oxide phases such as ZnO, CaO and Ca2Fe2O5. The EAF dust was first treated by hydrochloric acid leaching at pH = 3 which dissolved 63% of the zinc. The pyrometallurgical treatment of the leaching residue was studied using an induction heating system to simulate some important operations of EAF smelting of the residue in combination with steelmaking. The leaching residue was mixed with carbon powder to obtain a mixture with 52.1% ZnFe2O4 and 17.8% carbon. The mixture, scrap, and slag former were charged together in a crucible and heated to attain a melt temperature around 1650DGC. The effects of different amounts of mixture on the zinc balance and iron recovery were examined. Based on the test results, suggestions are made for the EAF recycling procedure of the leaching residue.
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| 29. |
- Tossavainen, Mia, et al.
(författare)
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Characteristics of steel slag under different cooling conditions
- 2007
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 27:10, s. 1335-1344
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Tidskriftsartikel (refereegranskat)abstract
- Four types of steel slags, a ladle slag, a BOF (basic oxygen furnace) slag and two different EAF (electric arc furnace) slags, were characterized and modified by semi-rapid cooling in crucibles and rapid cooling by water granulation. The aim of this work was to investigate the effect of different cooling conditions on the properties of glassy slags with respect to their leaching and volume stability. Optical microscopy, X-ray diffraction, scanning electron microscope and a standard test leaching (prEN 12457-2/3) have been used for the investigation. The results show that the disintegrated ladle slag was made volume stable by water granulation, which consisted of 98% glass. However EAF slag 1, EAF slag 2 and the BOF slag formed 17%, 1% and 1% glass, respectively. The leaching test showed that the glass-containing matrix did not prevent leaching of minor elements from the modified slags. The solubility of chromium, molybdenum and vanadium varied in the different modifications, probably due to their presence in different minerals and their different distributions.
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| 30. |
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| 31. |
- Yang, Qixing, et al.
(författare)
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A fundamental study on recycling of wastes from stainless steel plants via the electric arc furnace
- 2000
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Ingår i: 58th Electric Furnace Conference and 17th Process Technology Conference. - : Iron and Steel Society. - 1886362467 ; , s. 195-207
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Konferensbidrag (refereegranskat)abstract
- Waste briquettes of high carbon contents have been smelted using an induction furnace in tests to gain fundamental information for EAF operations of the briquette smelting. The briquettes amounted to 5-15% of the weights of the metal charges, stainless steel scrap and alloys.
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| 32. |
- Yang, Qixing, et al.
(författare)
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A laboratory study on smelt-reduction of briquettes made of wastes from stainless steel production
- 1999
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Ingår i: REWAS '99. ; , s. 1061-1072
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Konferensbidrag (refereegranskat)abstract
- Wastes from stainless steel production were briquetted together with carbon for smelt-reduction in the electric arc furnace, EAF, to achieve an internal recycling. A laboratory induction furnace was used to simulate the EAF to study the disintegration of the briquettes under heating and recovery of metals from briquettes melted together with stainless steel and slag-former. The influences of test conditions on carbon reduction of oxides in the briquettes were also examined. The briquettes endured heating at 1186°C under load and could be charged to the melt in small quantity without causing serious splashing. For a high metal recovery, it was necessary to charge the briquettes together with slag-former. Small local zones of smelt-reduction with high carbon concentration could thus be formed during heating. Silicon content in the metal near to the briquettes should be minimised to achieve a high degree of carbon reduction. Based on results obtained from this study, suggestions were made on smooth operations of smelt-reduction of the briquettes by using electric arc furnaces of large scale
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| 33. |
- Yang, Qixing, et al.
(författare)
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Smelting of EAF and BF dust in combination with scrap melting to recycle the by-products from steel industry
- 2005
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Ingår i: Proceedings of the REWAS '04. - : Minerals, Metals & Materials Society. - 8495520060 ; , s. 2729-2738
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Konferensbidrag (refereegranskat)abstract
- The baghouse dust generated from the electric arc furnace (EAF) process must be treated using environmentally and economically sound methods. One treatment step is to smelt the dust in the EAF so the dust can be upgraded for further processing. Parameters related to optimum dust smelting in the EAF were studied in the present laboratory tests. An induction furnace was used to smelt test charges, steel parts weighing 5 kg, slag formers and the EAF dust pellets (EAFDP) with a steel weight of 2%. Eight tests were performed. Reducing agents for Zn oxides in the EAFDP were coke, blast furnace dust, solid iron and liquid iron with temperature of 1650°C. Influences of contacts between the EAFDP and reducing agents on Zn dissolution in liquid steel were examined in some detail. It was demonstrated by the tests that material mixing and heating were important for minimizing the impact of the EAFDP smelting on steel and slag properties when using either coke or blast furnace dust as reducing agents. Based on results from the present laboratory tests, some suggestions were made for production-scale recycling of EAFDP in the EAF
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| 34. |
- Yazawa, Akira, et al.
(författare)
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Thermodynamic evaluations on the formation of dioxins and furans in combustion gas
- 1999
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Ingår i: Chemosphere. - 0045-6535 .- 1879-1298. ; 39:14, s. 2419-2432
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Tidskriftsartikel (refereegranskat)abstract
- The formation of toxic PCDD/Fs are discussed thermodynamically for C---O---H---Cl quaternary combustion gas to elucidate the effects of temperature and gas composition. In most cases, these toxic gases are formed at a temperature below 400°C, representing the isomers of furans and tetra dioxin (4CDD) in similar amounts, but those of other dioxin isomers are much lower.The amounts of PCDD/Fs species formed depend greatly on the gas composition, but are always associated with the formation of chlorobenzenes. When the system contains excess oxygen such as O/C > 1, PCDD/Fs decrease sharply.Hydrogen and water vapor are quite effective in decomposing dioxins and furans to form benzene and hydrocarbons. The derived amounts of PCDD/Fs are much higher than those observed in practice because of kinetic reasons. Taking account of kinetic factors, reasonable amounts of these toxic gases are derived.Especially, the reaction of carbon deposition has always been neglected in thermodynamic calculation of PCDD/Fs because of kinetic reason, but both of solid carbon and PCDD/Fs must be coexisting in small amounts.
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