1. Recovery of phosphorus and metals from the ash of sewage sludge, municipal solid waste, or wood biomass : a review and proposals for further useSara Tominc, Vilma Ducman, Wolfgang Wisniewski, Terttu Luukkonen, Kirkelund Gunvor M., Ottosen Lisbeth M., 2023, izvirni znanstveni članek Povzetek: This review provides an overview of methods to extract valuable resources from the ash fractions of sewage sludge, municipal solid waste, and wood biomass combustion. The resources addressed here include critical raw materials, such as phosphorus, base and precious metals, and rare earth elements for which it is increasingly important to tap into secondary sources in addition to the mining of primary raw materials. The extraction technologies prioritized in this review are based on recycled acids or excess renewable energy to achieve an optimum environmental profile for the extracted resources and provide benefits in the form of local industrial symbioses. The extraction methods cover all scarce and valuable chemical elements contained in the ashes above certain concentration limits. Another important part of this review is defining potential applications for the mineral residues remaining after extraction. Therefore, the aim of this review is to combine the knowledge of resource extraction technology from ashes with possible applications of mineral residues in construction and related sectors to fully close material cycle loops.
Ključne besede: critical raw materials, extraction, sewage sludge ash, municipal solid waste incineration ash, wood biomass ash
Objavljeno v DiRROS: 03.11.2023; Ogledov: 376; Prenosov: 138
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2. Characterizing the interfacial zones of fly ash based alkali activated adhesives to various substratesWolfgang Wisniewski, Vilma Ducman, 2022, izvirni znanstveni članek Povzetek: Alkali Activated Materials (AAMs) are important potential substitutes for cement in many materials. The AAMs presented here are based on industrial ground granulated blast furnace slag (GGBFS) and fly ash (FA). They are tested for their suitability as adhesives for joining concrete, ceramic tiles, a wood-based geopolymer (WGP) and a high density geopolymer (HDGP). After mixing multiple batches and performing preliminary tests of the resulting shrinkage, bending-, compressive- and pull-of-strengths to standard ceramic tiles, selected mixtures are tested for their open time and applied to bond intended substrates. The interfacial zones (ITZ) of an AAM containing additional KOH and the most comparable KOH-free AAM to concrete, ceramic tiles, WPG and HDGP are subsequently characterized in detail using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). Both mechanical interlocking and areas of probable chemical bonding are identified.
Ključne besede: adhisive, fly ash, ITZ, pull of test, open ccess
Objavljeno v DiRROS: 21.06.2023; Ogledov: 327; Prenosov: 226
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3. Microstructural characterization of alkali-activated composites of lightweight aggregates (LWAs) embedded in alkali-activated foam (AAF) matricesKatja Traven, Wolfgang Wisniewski, Mark Češnovar, Vilma Ducman, 2022, izvirni znanstveni članek Povzetek: Alkali-activated composites of lightweight aggregates (LWAs, with beneficial insulating properties) and alkali-activated foams (AAFs, higher added value products due to their production from waste materials at well below 100 ◦C) allow for the expectation of superior properties if a chemical bonding reaction or mechanical interlocking occurs during production. However, the interfaces between LWAs and an AAF have not been studied in detail so far. Chemical reactions are possible if the LWA contains an amorphous phase which can react with the alkaline activators of the AAF, increase the bonding, and thus, also their mechanical strengths. These, in turn, allow for an improvement of the thermal insulation properties as they enable a further density reduction by incorporating low density aggregates. This work features a first-detailed analyses of the interfaces between the LWAs’ expanded polystyrene, perlite, expanded clay and expanded glass, and the alkali-activated foam matrices produced using industrial slags and fly ash. Some are additionally reinforced by fibers. The goal of these materials is to replace cement by alkali-activated waste as it significantly lowers the environmental impact of the produced building components.
Ključne besede: alkali activated materials/geopolymers, light weight aggregates, SEM
Objavljeno v DiRROS: 20.06.2023; Ogledov: 358; Prenosov: 185
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4. Clay rich river sediments calcined into precursors for alkali activated materialsLea Žibret, Wolfgang Wisniewski, Barbara Horvat, Mojca Božič, Boštjan Gregorc, Vilma Ducman, 2023, izvirni znanstveni članek Povzetek: Alkali activated materials (AAMs), a potential alternative to cement-based products or ceramics, can incorporate large amounts of currently landfilled aluminosilicate rich materials such as calcined clay-rich river sediments collected at hydropower plant dams. Untreated fresh sediment and untreated aged sediment intended to serve as AAM precursors were calcined to increase their amorphous content, then activated by Na or K-based silicate or hydroxide solutions and cured at 60 ◦C for three days.
Up to 30 mass % (ma%) of fly ash (FA) or ladle slag (LS) increased the mechanical performance. The phase composition and microstructure are analyzed using X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and mercury intrusion porosimetry to gain further insight into how the additives influence the final properties of the resulting AAMs. The main crystalline components of the prepared AAMs are quartz, illite/muscovite and feldspar. The amorphous content reaches up to 52.5 ma% in the Na-activated AAMs and up to 48.8 ma% in K-activated AAMs. The acquired results confirm the suitability of the investigated sediments as sole precursors for AAMs. The mechanical properties of the AAMs can be improved by adding FA and/or LS.
Ključne besede: sediments, alkali activated materials, properties
Objavljeno v DiRROS: 30.05.2023; Ogledov: 319; Prenosov: 249
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