| 1. |
- Hellgren, Simon, et al.
(författare)
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The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction
- 2024
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Ingår i: Metals. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2075-4701. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Super-hot acid leach residue is generated during zinc production in the roasting–leaching–electrowinning route, where both primary and secondary resources are used as feed material. This residue may contain valuable metals, such as lead, zinc, and iron, as well as precious metals, such as gold and silver. Four materials, namely super-hot acid leach residue, a residue formed when super-hot acid leach residue is selectively leached for lead with triethylenetetramine, as well as flotation concentrate, and flotation tailings formed in a selective silver flotation process with super-hot acid leach residue as the feed material were characterized to obtain a deeper understanding of possible further metal extraction. These four materials were characterized for chemical composition, mineralogy, and mineral distribution via chemical analyses, X-ray diffraction, and energy-dispersive scanning electron microscopy, respectively. The scanning electron microscope images showed that the materials have large variations in particle size distribution and composition. The results showed that the main lead phase in super-hot acid leach residue is lead sulfate, whereas it is mostly converted to lead sulfide during the selective lead leaching of the super-hot acid leach residue. The remaining lead sulfate is found in a solid solution with barium sulfate. Extracting lead from super-hot acid leach residue via triethylenetetramine leaching resulted in increased concentrations of gold and silver by 41% and 42%, respectively. The identified silver phases in super-hot acid leach residue may correspond to silver sulfide, silver chloride, and elementary silver, where silver sulfide was the most commonly occurring silver phase. After leaching this selectively for lead with triethylenetetramine, similar silver phases were identified, but silver sulfide and silver chloride occurred to a similar extent. Additionally, silver copper sulfide was detected. The presence of different silver phases might pose a challenge to reaching high silver recovery during leaching as the optimum leaching conditions differ somewhat. Furthermore, elemental sulfur, with a tendency to coat gold and silver particle surfaces, which is indicated to be present in all materials except the silver flotation tailings, may hinder metal extraction.
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| 2. |
- Andersson, Anton, et al.
(författare)
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A Method for Synthesizing Iron Silicate Slags to Evaluate Their Performance as Supplementary Cementitious Materials
- 2023
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Ingår i: Applied Sciences. - : Mdpi. - 2076-3417. ; 13:14
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R-3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags.
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| 3. |
- Andersson, Anton, et al.
(författare)
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Ground granulated iron silicate slag as supplementary cementitious material: Effect of prolonged grinding and granulation temperature
- 2023
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Ingår i: Cleaner Materials. - : Elsevier. - 2772-3976. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The metallurgical and cement industries contribute significantly to anthropogenic carbon dioxide emissions. Utilizing oxidic by-products from the metallurgical industry as supplementary cementitious materials (SCMs) can improve resource efficiency and reduce emissions from cement production. Iron silicate copper slags have been studied as SCMs, but mainly in systems where Portland cement is used as an activator. There is limited research on the inherent reactivity of the slag under changing processing conditions. The present study offers insight into the effect of granulation temperature and grinding on the inherent reactivity of an industrially produced iron silicate copper slag. The results showed that granulation temperature had an insignificant effect on reactivity, while grinding generated substantial improvements. The latter effect was concluded to stem from the increased specific surface area, increased number of sites for nucleation and growth of hydrates, and changes in the inherent reactivity owing to structural changes induced by the grinding.
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| 4. |
- Andersson, Anton, et al.
(författare)
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Insights into the Valorization of Electric Arc Furnace Slags as Supplementary Cementitious Materials
- 2023
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 10, s. 96-109
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Tidskriftsartikel (refereegranskat)abstract
- The transition to hydrogen-based reduction processes within the iron and steelmaking industry will generate new types of slag compositions that require valorization routes. Using slags as supplementary cementitious materials (SCMs) addresses the carbon dioxide emissions of the cement industry since the SCM requires neither calcination nor clinkering. Conventionally, ironmaking slags from the blast furnace (BF) are recycled as SCMs, i.e., ground granulated BF slag (GGBS). Ideally, future slags from electric arc furnaces (EAFs) operating on hydrogen-based direct reduced iron should be valorized analogously. Since the hydrogen-based process route is not yet realized in an industrial scale, the literature lacks data to support this valorization route, and additionally, literature on scrap-based EAF slags is scarce. Therefore, the present study aimed to offer insights into the utilization of ore-based EAF slags as SCMs based on an industrial slag sample from an EAF operating on hot briquetted iron. The slag was remelted, modified, and water-granulated in laboratory scale, and its performance as an SCM was compared to water-granulated ladle slag and two commercial GGBS. The results showed promising reactivities measured using the R3 isothermal calorimeter-based testing protocol. Based on the comparison to GGBS, the study indicated that generating reactive and appropriate SCMs from EAF slags will partly be a challenge in balancing the crystallization of the MeO-type solid solution rich in magnesia and addressing the iron oxide content in the amorphous phase.
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| 5. |
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| 6. |
- Fokkens, Jelle Tjeerd, 1992, et al.
(författare)
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Cognitively adequate complexity of reasoning in a description logic
- 2023
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Ingår i: CEUR Workshop Proceedings. Joint of the 2nd Workshop on Knowledge Diversity and the 2nd Workshop on Cognitive Aspects of Knowledge Representation, KoDis + CAKR 2023, Rhodes, Greece, September 3-4, 2023 / Baker C., Alvarez L.G., Heyninck J., Heyninck J., Meyer T., Penaloza R., Vesic S. (eds.). - 1613-0073.
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Konferensbidrag (refereegranskat)abstract
- The problem of finding automated and cognitively adequate explanations for entailments in knowledge bases is tackled by modelling a deductive reasoning process with the cognitive architecture ACT-R. This results in the model sharp which simulates the reasoning process of a human executing an algorithm for deciding inconsistency of an ALE ABox. With sharp one can make certain predictions about the inference time of this reasoning process. Based on the inference time two complexity measures are defined that are expectedly cognitively adequate by design.
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| 7. |
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| 8. |
- Kero Andertun, Jakob, et al.
(författare)
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Characterisation and leaching behaviour of granulated iron silicate slag constituents
- 2022
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Ingår i: Canadian metallurgical quarterly. - : Taylor & Francis. - 0008-4433 .- 1879-1395. ; 61:1, s. 14-23
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Tidskriftsartikel (refereegranskat)abstract
- Due to increased copper production and the associated environmental consequences, copper production processes need to be improved, considering the impact of their byproducts, among others slag. This study investigated the leaching of individual constituents of iron silicate slag from a copper smelter. This was done by characterising granulated samples of its constituents – glass, matte, speiss – to determine their leaching contribution. It was observed that leaching in distilled and deionised water without pH regulation achieved various natural pH for the constituents. At natural pH, glass (Cu, Zn) and speiss (Ni, Sb) contributed to leaching. Static pH titrations showed the increased leaching of Zn, Cu, Ni, As, and Sb with decreasing pH. The results showed that, an iron silicate slag consisting of glass, matte and speiss, contributes to leaching as follows: matte – Cu and Ni, speiss – Cu, Ni, As, and Sb. Zn leaching is similar among the constituents.En raison de l’augmentation de la production de cuivre et des conséquences environnementales associées, on a besoin d’améliorer les processus de production du cuivre, tenant compte de l’impact de leurs sous-produits, parmi lesquels les scories. Cette étude a examiné la lixiviation des constituants individuels des scories de silicate de fer provenant d’une fonderie de cuivre. Ceci a été accompli en caractérisant les échantillons granulés de ses constituants –verre, matte, smaltite–pour déterminer leur contribution à la lixiviation. On a observé que la lixiviation dans de l’eau distillée et désionisée sans régulation du pH atteignait divers pH naturels pour les constituants. Au pH naturel, le verre (Cu, Zn) et la smaltite (Ni, Sb) contribuaient à la lixiviation. Les titrages de pH statique ont montré une augmentation de la lixiviation du Zn, Cu, Ni, As et Sb avec une diminution du pH. Les résultats ont montré que les scories de silicate de fer composées de verre, de matte et de smaltite contribuent à la lixiviation comme suit: matte–Cu et Ni, smaltite–Cu, Ni, As et Sb. La lixiviation du Zn est similaire parmi les constituants.
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| 9. |
- Kero Andertun, Jakob
(författare)
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Leaching of water-granulated iron silicate slags and their compounds : A study of synthetic and industrial slag systems
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Copper smelter slag is a residue product of the pyrometallurgical extraction of copper. Due to its physical properties, the iron silicate type of copper smelter slag has many possible application areas, e.g., different aggregates and abrasives. During the copper-making process, some copper becomes distributed in the slag; therefore, copper recovery from the slag is commonly done through slag treatment processes. Despite treatment, copper-containing inclusions can remain in the final slag. In order to secure the environmental properties of slags containing inclusions, the leaching mechanisms needs to be understood, which is the focus of the thesis presented.Synthetic and industrial iron silicate slags have been studied with respect to the impact of the slag constituent’s oxide (glass), sulfide (matte) and metalloids (speiss) on leaching as well as the impact of chemical composition (ZnO and CaO content). The synthetic slags are melted in laboratory furnaces. The industrial slags have undergone a Zn-fuming and settling process (including CaO additions for some slags) to recycle and reduce the zinc content and further separate copper-containing inclusions such as sulfide (matte) and metalloid (speiss) species. The materials investigated in the thesis are solidified using water granulation.All materials are characterized by their chemical compositions and mineralogy. Further, industrial slag constituents are investigated regarding their leaching contribution. Syntheticiron silicate (oxide) is investigated regarding the influence of ZnO content and granulation temperature on Zn leaching. CaO-modified industrial iron silicate slags are investigated regarding the leaching of specific elements (e.g., Cu, Zn, Ni, As, Sb). The leaching tests examine the effect of pH, oxidation and time using water leaching, acid and oxidating leaching and dynamic leaching methods.Characterizing the slag constituents shows that the glass mainly contains amorphous iron silicate. The matte contains mainly copper sulfides, and speiss contains copper metalloids. The leaching results show that the glass contributes to Cu and Zn leaching at pH 8.4, and the speiss contributes to Ni and Sb leaching at pH 7.8. Further, the leaching contribution of matte and speiss increased with decreasing pH. The main leaching elements from the matte and speiss include Cu, Ni, As and Sb.Characterization of the ZnO-modified iron silicate shows that Zn is mainly distributed in glass and partly in fayalite. Further, the Zn leaching increases with granulation temperature, ZnO content in the glass and decreasing pH.Characterization of CaO-modified slags shows that up to 20 wt.% CaO dissolves into the glass phase. An increased CaO content resulted in increased Ca leaching, yielding higher pH. Leaching of Zn, Cu, Ni and Sb was on the other hand shown to decrease. Further, long-term leaching studies confirm increasing pH and Ca leaching. In contrast, the leaching of Cu, Zn and Ni showed a peak after a certain time, which was lowered with increasing CaO content in the slags. The leaching of As and Sb increased with increasing leaching time, but the increase diminished with increasing CaO content in the slags. A lower pH and an oxidating environment increased the leaching of Zn, Cu and Ni.The summarized results from this thesis indicate that the glass contributes to Zn leaching while copper-containing inclusions matte and speiss contribute to the leaching of Cu, Ni, As and Sb. The leaching of elements from the copper-containing inclusions matte and speiss can be limited by ensuring a pH buffer preventing acidification, for example, by CaO modification. CaO modifications decrease the slag leaching resistance, which contributes to increasing pH in the leachate by Ca-dissolution and hence decreased leaching of copper-containing inclusions in the slag. Also, the Zn leaching from the slag decreased with increasing pH in the leachate.
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| 10. |
- Kero Andertun, Jakob, 1991-, et al.
(författare)
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Long-Term Leaching Effects on CaO-Modified Iron Silicate Slag
- 2022
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Ingår i: Minerals. - : MDPI. - 2075-163X. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- Granulated iron silicate slag, a by-product of pyrometallurgical copper extraction, has excellent properties for construction applications. Slag modification with CaO enhances the application properties regarding pozzolanic reactivity, potentially extending slag use in the future. The slags’ short-term leaching behavior has already been investigated with promising results, while the long-term leaching effects are less studied. Therefore, this study aims to determine the long-term leaching effects on CaO-modified iron silicate slags. The CaO-modifications were conducted during full-scale slag treatment operation. The slags were characterized and leached, and the remaining slags were investigated regarding the formation of secondary phases. The long-term leaching of main and trace elements was determined over 30 days using a dynamic leaching method corresponding to an extended time period. The leaching tests showed increased leaching of the main slag elements (Si, Ca). Zn and Cu showed peak leaching after four days of leaching, and the leaching of As and Sb decreased with the increasing CaO content in the samples. After dynamic leaching, secondary phases formed on the Cu-containing inclusions on the sample surfaces. Independent of the CaO content, the leaching of Cu was increased when subjected to external acidic and oxidating conditions using static pH titration at pH 5 in dilute nitric acid.
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