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| 2. |
- Ahmed, Hesham, et al.
(author)
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Alternative Reducing Agents for Sustainable Blast Furnace Ironmaking
- 2017
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In: ESTAD 2017.
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Conference paper (peer-reviewed)abstract
- Lowering of CO2 emission from the integrated steel industry as well as minimizing theneed for landfill are important challenges in the focus for the integrated steel industry. With thisaim collaborative research projects have been conducted and are on-going on the possible useof renewable reducing agents or such with high content of H2 as well as for enabling recyclingof 1in-plant fines so far not possible to use. Due to contents of undesired impurities the blastfurnace (BF) sludge has to be pre-treated in an appropriate way before carbon and iron oxidecan be valorized. In order to understand the impact of alternative reducing agents as injectedthrough the tuyeres or part of top charged agglomerates containing iron oxide, samples oftorrefied biomass, plastic and in-plant fines have been analyzed by means of thermogravimetricanalyzer coupled with a mass spectrometer (TGA-MS).The results proved that effective utilization of carbon bearing BF dust and sludge as analternate reducing agent could be realized and can be implemented into BF after adequateupgrading. Plastic materials and biomass based reductants decomposition is associated with therelease of volatiles. The main contents of these volatiles are CO, H2 and hydrocarbon which areall known for their reduction potential. Moreover, injection of such materials is expected toimprove process efficiency and sustain the gas permeability along the BF cohesive zone. Onthe other hand, top charging of these materials would improve the energy and materialefficiency in the BF due to their higher reactivity compared to conventional carbon.
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| 3. |
- Lotfian, Samira
(author)
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Alternative reducing agents in metallurgical processes : Experimental study of thermal characterization of shredder residue material
- 2016
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Licentiate thesis (other academic/artistic)abstract
- Coal used in metallurgical processes can participate in reduction reactions to produce metals and alloys from oxides. Base metals production leads to generation of slag, which contains valuable metals that can be recovered and recycled. There are several options to treat the slag, depending on the metal content in the slag. One is slag fuming, which is a well-established process that is traditionally used to vaporize zinc from zinc containing slags, mainly lead blast furnace slag, but is applied in a few plants for copper smelting slags. In this process reduction is achieved using pulverized coal, lump coal or natural gas. Conventionally pulverized coal injected to the furnace is utilized both to participate in reduction reactions and also to supply heat. On the other hand, the amount of possible alternative reducing agents such as residue plastic material is increasing steadily and the issue of sustainable disposal management of these materials has arisen. As carbon and hydrogen are major constituents of the residue plastic-containing materials, they have the potential to be an auxiliary source of reducing agents, to partially replace conventional sources such as coal. Shredder Residue Material (SRM) is a plastic-containing residue material after separation of main metals. Utilization of SRM as an alternative reducing agent, would lead to not only decreased dependency on primary sources such as coal but also to an increase in the efficiency of utilization of secondary sources. This calls for systematic scientific investigations, wherein these secondary sources are compared with primary sources with respect to e.g., devolatilization characteristics, gasification characteristics and reactivity. As a first step, devolatilization characteristics of SRM are compared with those of coal using thermogravimetric analysis. To study the reduction potential of the evolved materials, composition of evolved off-gas was continuously monitored using quadrupole mass spectroscopy. To gain a better understanding of possible interaction of plastics in a mixture, the devolatilization mechanisms and the volatile composition of three common plastics; polyethylene, polyurethane and polyvinylchloride and their mixture have been studied. Furthermore, gasification characteristics and reactivity of char produced from SRM is compared with coal char. The effect of devolatilization heating rate on gasification rate of char was investigated. Proximate analysis has shown that SRM mainly decomposes by release of volatiles, while coal shows high fixed carbon content, which is reported to contribute to reduction reactions. The composition of volatiles shows H2, CO and hydrocarbons which are known to have reduction potential. Therefore, it is essential that SRM be used in a process that could utilize the evolved volatiles for reduction. The results confirm the interaction between the plastics within the binary and ternary mixtures, which suggests that similar phenomenon may occur during devolatilization of SRM. Although the char produced from SRM contains lower amounts of fixed carbon compared to coal char, it has a porous structure and high surface area, which makes it highly reactive during gasification experiments. In addition to physiochemical properties, the catalytic effect of ash content of SRM char contributes to its higher reactivity and lower activation energy value compared to coal char. Moreover, the gasification reactivity of char produced at fast devolatilization heating rate was highest, due to less crystalline structure of produced char.
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| 4. |
- Lotfian, Samira, et al.
(author)
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Alternative reducing agents in metallurgical processes : devolatilization of Shredder Residue Materials
- 2017
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In: Journal of Sustainable metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 3:2, s. 311-321
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Journal article (peer-reviewed)abstract
- Plastic-containing shredder residue material has the potential to be used as an alternative reducing agent in nonferrous bath smelting processes. This would lead to not only decreased dependency on primary sources such as coal or coke but also to an increase in the efficiency of utilization of secondary sources. This calls for systematic scientific investigations, wherein these secondary sources are compared with primary sources with respect to devolatilization characteristics, combustion characteristics, reactivity, etc. As a first step, in this paper, devolatilization characteristics of plastic-containing shredder residue material (SRM) are compared to those of coal using thermogravimetric analysis. Proximate analysis has shown that SRM mainly decomposes by release of volatiles, while coal shows high fixed carbon content, which is reported to contribute to reduction reactions. To study the reduction potential of the evolved materials, composition of evolved off-gas was continuously monitored using quadrupole mass spectroscopy. The composition of volatiles shows H2, CO, and hydrocarbons which are known to have reduction potential. Therefore, it is essential that SRM would be used in a process that could utilize the evolved volatiles for reduction. Furthermore, to understand the potentials of different plastic materials as reducing agents, the devolatilization mechanisms and volatile composition of three common plastics, namely, polyethylene, polyurethane, and polyvinylchloride and their mixtures have been studied. The results show the interaction between the plastics within the binary and ternary mixtures. Similar phenomena may occur during devolatilization of SRM, which contains different type of plastics.
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| 5. |
- Lotfian, Samira, et al.
(author)
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Alternative reducing agents in metallurgical processes : gasification of shredder residue material
- 2017
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In: Journal of Sustainable metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 3:2, s. 336-349
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Journal article (peer-reviewed)abstract
- Shredder residue material (SRM) contains plastic material, which has a potential to replace metallurgical coal for reduction during bath-smelting processes. Among the important parameters affecting its implementation are the gasification and the reactivity of char. Therefore, prior to considering its application in metallurgical processes, the gasification characteristics of the produced char need to be studied. Although the char produced from SRM contains lower fixed carbon compared with coal char, it has a porous structure and high surface area, which makes it highly reactive during gasification experiments. In addition to physiochemical properties, the catalytic effect of ash content of SRM char is attributed to its higher reactivity and lower activation energy compared with coal char. Furthermore, the effect of devolatilization heating rate on the gasification characteristics of produced char is investigated. It was found that the devolatilization heating rate during char production has a considerable effect on morphological properties of the char product. Moreover, the gasification reactivity of char produced at a fast devolatilization heating rate was the highest, due to the less crystalline structure of the produced char.
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| 6. |
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| 7. |
- Lotfian, Samira, et al.
(author)
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Conversion Characteristics of Alternative Reducing Agents for the Bath Smelting Processes in an Oxidizing Atmosphere
- 2019
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In: Journal of Sustainable Metallurgy. - New York : Springer. - 2199-3823 .- 2199-3831. ; 5:2, s. 230-239
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Journal article (peer-reviewed)abstract
- The amount of plastic-containing materials, such as shredder residue material, which is generated after the processing of electronic equipment waste, is increasing. One interesting option for the sustainable management of these materials, instead of incineration or landfilling, is recycling through injection in a bath smelting process, such as zinc fuming. In this way, the plastic material could partially substitute coal as a reductant in the process. In such processes, shredder residue material is injected alongside air into the furnace at temperatures up to 1250 °C. Once the material is injected, it undergoes several conversion steps, including ignition, devolatilization, and char oxidation. In this study, the conversions of shredder residue material and other pure plastic materials were investigated using a drop tube furnace and an optical single-particle burner. The effect of particle size on the conversion time of each material was studied. The conversion time of the particles increases as the particle size increases, although the relationship is not linear. The results indicate that plastic materials with a particle size range of 1–7 mm have a considerably longer conversion time than that of coal used in the conventional processes.
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| 8. |
- Lotfian, Samira, et al.
(author)
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Evaluating the potential of plastic-containing materials as alternative reducing agents
- 2019
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In: Canadian metallurgical quarterly. - : Taylor & Francis. - 0008-4433 .- 1879-1395. ; 58:4, s. 389-399
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Journal article (peer-reviewed)abstract
- The amount of discarded plastic-containing materials is increasing, and one option to help with this issue is to use these materials in bath smelting processes. The injection of plastic-containing materials to partially substitute coal in zinc-fuming processes has been studied in an industrial trial at Boliden–Rönnskär smelter. To evaluate the potential of plastic-containing materials, thermodynamic calculations were performed in this study. In the first step, a thermodynamic calculation was performed for trials with only coal injection, and then this calculation was applied to trials with the co-injection of plastic materials. The thermodynamic calculation shows that not all the injected coal participates in the reactions within the slag. Similarly, the calculation with the co-injection of plastic-containing materials shows that different amounts of each plastic material participate in the reactions within the slag bath.
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| 9. |
- Lotfian, Samira, et al.
(author)
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Plastic-containing materials as alternative reductants for base metal production
- 2019
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In: Canadian metallurgical quarterly. - : Taylor & Francis. - 0008-4433 .- 1879-1395. ; 58:2, s. 164-176
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Journal article (peer-reviewed)abstract
- Shredder residue materials are produced after the removal of ferrous and non-ferrous fractions from end-of-life electronic equipment. Despite the high plastic content and metal value in the ash, high percentages of these materials are currently sent to landfills. In this study, the potential of utilising shredder residue material and other plastic-containing materials as reducing agents was studied. Plastic-containing materials were co-injected with coal into a zinc-fuming furnace in Boliden-Rönnskär smelter. The data obtained from the trial, such as the data from the chemical analysis of the slag and the steam production, are discussed. The observations indicate that plastic-containing material can replace up to 1 ton h−1 of coal without a significant decrease in the zinc reduction rate.
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| 10. |
- Lotfian, Samira, et al.
(author)
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Sustainable Management of the Plastic-Rich Fraction of WEEE by Utilization as a Reducing Agent in Metallurgical Processes
- 2019
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In: Applied Sciences. - : MDPI. - 2076-3417. ; 9:20
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Journal article (peer-reviewed)abstract
- In modern society, there is a fast growth in the production of electrical and electronic equipment (EEE); however, rapid growth results in the frequent discarding of this equipment. During the treatment of discarded materials, a stream is generated that contains a high fraction of plastic materials, but also metals and oxides. This stream, which is called shredder residue material (SRM), is heterogeneous, which limits its recycling options. Utilizing this material in metallurgical processes allows the plastic fraction to be used as a reductant and energy source and the metallic fraction to be recycled and returned to the production of EEE. The aim of this study was to evaluate the potential of plastic-containing materials, especially SRM, as alternative reductants in metallurgical processes. The first step was to compare the thermal conversion characteristics of plastic-containing materials to the currently used reducing agent, i.e., coal. Three main candidates, polyurethane (PUR), polyethylene (PE), and SRM, were studied using a drop tube furnace and an optical single-particle burner. PE had the highest volatile content and the fastest conversion time, whereas PUR had the longest conversion time. Thereafter, plastic materials were tested at the industrial scale through injection to the zinc fuming process at the Boliden Rönnskär smelter. During the industrial trial, the amount of coal that was injected was reduced and substituted with plastic material. The results indicate the possibility of reducing the coal injection rate in favor of partial substitution with plastic materials.
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