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Dr. Sossio Fabio Graziano
Pharmacy Department, Federico II University, 49-80131 Naples, Italy
Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino, 10129 Torino, Italy
Department of Earth Sciences, University of Torino, 10124 Torino, Italy
Department of Civil, Environmental and Architecture Engineering, Università degli Studi di Cagliari, 09124 Cagliari, Italy
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Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation

Abstract submission deadline
30 September 2025
Manuscript submission deadline
30 November 2025
Viewed by
37898

Topic Information

Dear Colleagues,

Recycling waste generated by the industrial exploitation of georesources could enhance the utilization of the useful minerals they contain, such as rare earth elements (REEs), critical raw materials (CRMs) and secondary raw materials. Consciously recovering quarry waste or reusing the waste produced by processing operations for georesources means considering them no longer as waste, but as secondary raw materials to be used in further production processes from the perspective of a circular economy; this thus enables vital objectives, such as the following, to be pursued:

  • The recovery of mineral raw materials resulting in the opening of new markets;
  • A reduction in landfills (up to their possible removal), resulting in soil dumping and a reduced impact on the landscape;
  • A reduction of business burdens related to the disposal and generation of added value related to the sale of mineral concentrates directly from quarries.

Herein, this Topic aims to collect original research articles and review papers.

The scope of this Topic includes, but is not limited to, the following areas of interest:

  • industrial waste management;
  • secondary raw materials;
  • exploitation of industrial by-products;
  • natural deposits and recovery of critical metals from waste materials and landfills;
  • innovative approaches for mineral exploitation;
  • sustainability in industrial processing;
  • sustainability in quarrying waste disposal.

Dr. Sossio Fabio Graziano
Dr. Rossana Bellopede
Dr. Giovanna Antonella Dino
Dr. Nicola Careddu
Topic Editors

Keywords

  • quarry waste
  • rare earth elements
  • critical raw materials
  • secondary raw materials
  • environmentally-friendly materials
  • landfill disposal alternative

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Materials
materials 		3.1 5.8 2008 13.9 Days CHF 2600 Submit
Mining
mining 		- 2.8 2021 21.1 Days CHF 1000 Submit
Recycling
recycling 		4.6 6.8 2016 20.9 Days CHF 1800 Submit
Resources
resources 		3.6 7.2 2012 26.1 Days CHF 1600 Submit
Sustainability
sustainability 		3.3 6.8 2009 19.7 Days CHF 2400 Submit
Minerals
minerals 		2.2 4.1 2011 18 Days CHF 2400 Submit
Geosciences
geosciences 		2.4 5.3 2011 23.5 Days CHF 1800 Submit
Environments
environments 		3.5 5.7 2014 22.8 Days CHF 1800 Submit

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Published Papers (24 papers)

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17 pages, 1789 KiB  
Article
Studying the Sintering Behavior of H2-Reduced Bauxite Residue Pellets Using High-Temperature Thermal Analysis
by Dali Hariswijaya and Jafar Safarian
Materials 2025, 18(10), 2378; https://doi.org/10.3390/ma18102378 - 20 May 2025
Abstract
Treating bauxite residue as an alternative source of metals for iron and aluminum industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with a H2-based process is an important step for the decarbonization of metal [...] Read more.
Treating bauxite residue as an alternative source of metals for iron and aluminum industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with a H2-based process is an important step for the decarbonization of metal industry. In this study, bauxite residue (BR) pellets were prepared and were reduced with different H2-H2O gas compositions at different temperatures, which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)2 powders and sintered at 1150 °C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H2-H2O gas mixtures, which resulted in the reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400 °C to study their sintering behavior during H2 reduction using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) techniques to investigate the evolution of phases related to slag formation. Equilibrium module of Factsage™ was utilized to analyze results of thermal analysis. Both chemical and physical changes that occurred during the sintering process of the H2-reduced BR pellets were successfully detected by TG–DTA analysis, and the initial slag- and gas-phase formation were detected to occur from 900 °C and 1180 °C, respectively. One of the most notable chemical reactions to occur during the analysis was formation of mayenite at 810 °C, which is easily leachable, providing potential for recovery of alumina. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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17 pages, 4046 KiB  
Article
Effects of Ettringite Formation on the Stability of Cement-Treated Sediments
by Inácio Soares Ribeiro, Diego de Freitas Fagundes and Helena Paula Nierwinski
Resources 2025, 14(5), 73; https://doi.org/10.3390/resources14050073 - 28 Apr 2025
Viewed by 362
Abstract
This study explores the stabilization of dredged sediments classified as lean clay (CL) using hydrated lime, type III Portland cement, and compaction. While quicklime is commonly used in practice, this research explores alternative calcium-based binders with the aim of valorizing sediments for civil [...] Read more.
This study explores the stabilization of dredged sediments classified as lean clay (CL) using hydrated lime, type III Portland cement, and compaction. While quicklime is commonly used in practice, this research explores alternative calcium-based binders with the aim of valorizing sediments for civil engineering applications. The mechanical behavior of the treated materials was evaluated through an Unconfined Compressive Strength (UCS) test campaign, with the results interpreted using the porosity/volumetric cement content (η/Civ) index. This relationship assesses the influence of apparent dry density and cement content on the strength improvement of sediments, aiming to evaluate the suitability of the dredged sediments for engineering applications. A key feature of this study is the extended curing period of up to 90 days, which goes beyond the typical 28-day evaluations commonly found in the literature. Interestingly, strength degradation occurred at advanced curing ages compared to shorter curing times. To understand the mechanisms underlying this resistance degradation, the mixtures were subjected to X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These tests identified the presence of the expansive sulfate-based compound ettringite, which is associated with swelling and failure in soils stabilized with calcium-based stabilizers. This research contributes to the field by demonstrating the limitations of calcium-based binders in stabilizing sulfate-bearing dredged materials and emphasizing the importance of long-term curing in assessing the durability of treated sediments. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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16 pages, 20746 KiB  
Article
Pretreatment Methods for Recovering Active Cathode Material from Spent Lithium-Ion Batteries
by Federica Barontini, Flavio Francalanci, Eleonora Stefanelli and Monica Puccini
Environments 2025, 12(4), 119; https://doi.org/10.3390/environments12040119 - 12 Apr 2025
Viewed by 293
Abstract
The development of environmentally friendly pretreatment processes for spent lithium-ion batteries (LIBs) is crucial for optimizing direct recycling methods. This study explores alternative approaches for recovering active cathode materials from end-of-life LIBs, focusing on environmentally safer options compared to the usually employed toxic [...] Read more.
The development of environmentally friendly pretreatment processes for spent lithium-ion batteries (LIBs) is crucial for optimizing direct recycling methods. This study explores alternative approaches for recovering active cathode materials from end-of-life LIBs, focusing on environmentally safer options compared to the usually employed toxic solvent N-methyl-pyrrolidone (NMP), using disassembled batteries as test subjects. Various pretreatment methods, including thermal treatment, selective aluminum foil dissolution with a NaOH solution, and the use of eco-friendly solvents such as triethyl phosphate (TEP), are examined on the cathode sheets. The results show that thermal pretreatment combined with TEP provides the most effective approach, achieving a recovery efficiency of 95% while maintaining the morphology and purity of the recovered materials, making them suitable for direct recycling. These methods are further tested on complete battery cells, simulating industrial-scale operations. The TEP treatment proves particularly promising, ensuring high recovery efficiency and preserving the structural integrity of the materials, with a mean particle diameter of approximately 8 µm. Additionally, when applied to cycled batteries, this pretreatment successfully recovers active materials without contamination. This study provides valuable insights into various pretreatment strategies, contributing to the development of a greener, more efficient direct recycling pretreatment process for spent LIBs. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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13 pages, 4589 KiB  
Article
Development and Implementation of a Machine to Increase the Production and the Quality of a Compost
by Camila Mori de Oliveira, Andrea Sammito, Mauro Boano, Matteo Fischetti, Lorenzo Toso, Roberta Pizio, Rossana Bellopede and Paola Marini
Recycling 2025, 10(2), 62; https://doi.org/10.3390/recycling10020062 - 5 Apr 2025
Viewed by 268
Abstract
The composting sector plays a crucial role in the urban waste management system and is essential for advancing towards a circular economy. All organic matter can be entirely recovered from waste collection, except for the extraneous fractions present as impurities. In the studied [...] Read more.
The composting sector plays a crucial role in the urban waste management system and is essential for advancing towards a circular economy. All organic matter can be entirely recovered from waste collection, except for the extraneous fractions present as impurities. In the studied waste composting plant, three fractions are produced: >50 mm (waste not idoneous for compost), <12 mm (suitable for compost market) and 50–12 mm (overflow). The latter is used as inoculum and therefore recirculates many times, reducing the sizes of its constituents, which are mainly plastic films falling into the lower class <12 mm, where they are concentrated. The goal of this study is to reduce the quantity of undesirable materials present in the 50–12 mm class in order to increase the quality of the compost produced. For this reason, a compost characterization was carried out and a plant solution was proposed: the inclusion of a mesh conveyor belt, with beater rollers and an aspiration system at the end. The fine organic material passes through the mesh sieve, and it is moved apart from the overflow material, in which the light plastics are aspirated. More than 10% of the overflow weight is recovered as clean compost, with very low percentages of undesired remaining. A reduction in plastic impurity of 75% is reached. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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20 pages, 1917 KiB  
Article
Potential of Lipids from Polymer-Based Dewatered Sewage Sludge as Feedstock for Biodiesel Production
by Nor Afifah Khalil, Mohd Faizar Banjar, Fatin Najwa Joynal Abedin, Ahmad Noor Syimir Fizal, Norkhairi Ahmad, Muzafar Zulkifli, Wirach Taweepreda, Md Sohrab Hossain and Ahmad Naim Ahmad Yahaya
Sustainability 2025, 17(7), 2991; https://doi.org/10.3390/su17072991 - 27 Mar 2025
Viewed by 463
Abstract
Municipal wastewater treatment plants produce vast amounts of sewage sludge as waste, with more than 80% dewatered sludge (DS). DS is a polymer-based sludge containing flocculant and extracellular polymeric substances, including lipids. Lipids can be converted into biodiesel as an alternative energy that [...] Read more.
Municipal wastewater treatment plants produce vast amounts of sewage sludge as waste, with more than 80% dewatered sludge (DS). DS is a polymer-based sludge containing flocculant and extracellular polymeric substances, including lipids. Lipids can be converted into biodiesel as an alternative energy that reduces dependency on fossil fuels while helping cities manage waste more sustainably. Past studies explored the potential of lipids from various sewage sludges in biodiesel production. However, the potential of DS remains largely unexplored. This study evaluates the lipid extracted from DS and the potential of its fatty acid methyl ester (FAME) to be used as biodiesel. Lipid extraction was conducted under varying parameters, including temperatures of 70, 80, and 90 °C, extraction time of 2, 4, 6, and 8 h, and sludge-to-solvent (S/L) ratios of 0.05, 0.075, 0.1, 0.125, 0.15, and 0.175 g/mL. The optimal extraction conditions of 70 °C for 4 h at S/L of 0.175 g/mL yielded 1.71 ± 0.10% lipid. FTIR and TGA revealed that the DS lipids contain triglycerides, fatty acids, glycerol, and proteins. Transesterification of DS lipids produced DS FAME with a fatty acid profile ranging from C4:0 to C22:0. The evaluation of DS FAME revealed a high ester content (94.7%) of fatty acids ranging from C14:0 to C24:1, surpassing the minimum standard of 90% for biodiesel. The elevated proportion of unsaturated fatty acids in DS FAME is expected to result in a low melting point, reducing the solidifying effect and enhancing its performance as biodiesel. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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24 pages, 18613 KiB  
Article
Exploring the Recovery Potential of Critical and Strategic Raw Materials from Traversella Mine (Piedmont, Italy) Waste: A Comparison of Laboratory-Scale Separation Techniques
by Gabriele Baldassarre, Camila Mori De Oliveira, Adriano Fiorucci, Rossana Bellopede and Paola Marini
Mining 2025, 5(2), 21; https://doi.org/10.3390/mining5020021 - 21 Mar 2025
Viewed by 264
Abstract
The growing demand for green and, therefore, sustainable technologies present new challenges for our society. The European Union (EU) identified the critical raw materials (CRMs) and strategic raw materials (SRMs) necessary for these technologies and introduced policies to reduce reliance on external suppliers, [...] Read more.
The growing demand for green and, therefore, sustainable technologies present new challenges for our society. The European Union (EU) identified the critical raw materials (CRMs) and strategic raw materials (SRMs) necessary for these technologies and introduced policies to reduce reliance on external suppliers, which includes investigating the recovery of CRMs from extractive waste. This study assesses the recovery potential of mine waste collected in the Traversella mine district (Piedmont, Italy), known for its polymetallic Fe-Cu-W deposit. The characterization of waste rock samples involved chemical and mineralogical analyses, revealing metallic-bearing minerals such as magnetite and scheelite. Laboratory-scale magnetic and gravity separation tests were carried out and compared. Magnetic separation resulted in a recovery of 75.4% of Fe, 72.3% of Cu, and 83.7% of W, with a weak concentration. Instead, gravity separation produced high-grade Fe (67.6%) and W (1289 ppm) concentrate with lower recovery rates. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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33 pages, 29644 KiB  
Article
Gravity and Magnetic Separation for Concentrating Critical Raw Materials from Granite Quarry Waste: A Case Study from Buddusò (Sardinia, Italy)
by Antonello Aquilano, Elena Marrocchino and Carmela Vaccaro
Resources 2025, 14(2), 24; https://doi.org/10.3390/resources14020024 - 29 Jan 2025
Viewed by 906
Abstract
The Critical Raw Materials Act (CRMA), enacted by the European Union (EU) in May 2024, represents a strategic framework that aims to address the growing demand for critical raw materials (CRMs) and reduce dependency on non-EU sources. The present study explores the potential [...] Read more.
The Critical Raw Materials Act (CRMA), enacted by the European Union (EU) in May 2024, represents a strategic framework that aims to address the growing demand for critical raw materials (CRMs) and reduce dependency on non-EU sources. The present study explores the potential of CRMs recovery from granite extractive waste (EW) at a granite quarry in Buddusò (Sardinia, Italy). A significant quantity of granite EW, stored in piles within designated disposal areas at the quarry under study, is estimated in terms of mass and volume using GISs and digital elevation models (DEMs). Analysis performed using a scanning electron microscope attached to an energy-dispersive spectrometer (SEM-EDS) reveals the presence of allanite, a rare-earth-bearing mineral with substantial light rare-earth elements (LREEs), which can potentially be exploited for LREEs recovery. A combined working process including gravity and magnetic separations yields CRMs-enriched fractions with concentrations of REEs, Sc, and Ga, reaching levels of potential economic interest for different industrial applications. Despite promising concentrations, limited knowledge of allanite processing represents significant challenges for CRMs recovery from this waste. Therefore, the present study was conducted to assess the efficiency of these gravity and magnetic separation methods in order to concentrate CRMs from granite EW. Economic evaluations, including potential market value estimates, suggest that CRMs recovery from granite EW can be very profitable under optimized processing conditions. Expanding studies to other quarries in the region can provide valuable insights into the feasibility of establishing a recycling hub, offering a sustainable supply chain solution for CRMs within the EU’s strategic framework. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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43 pages, 4073 KiB  
Systematic Review
Concrete Mix Design of Recycled Concrete Aggregate (RCA): Analysis of Review Papers, Characteristics, Research Trends, and Underexplored Topics
by Lapyote Prasittisopin, Wiput Tuvayanond, Thomas H.-K. Kang and Sakdirat Kaewunruen
Resources 2025, 14(2), 21; https://doi.org/10.3390/resources14020021 - 28 Jan 2025
Cited by 3 | Viewed by 3796
Abstract
Recycled concrete aggregate (RCA) has been widely adopted in construction and emerged as a sustainable alternative to conventional natural aggregates in the construction industry. However, the study of holistic perspectives in recent literature is lacking. This review paper aims to provide a comprehensive [...] Read more.
Recycled concrete aggregate (RCA) has been widely adopted in construction and emerged as a sustainable alternative to conventional natural aggregates in the construction industry. However, the study of holistic perspectives in recent literature is lacking. This review paper aims to provide a comprehensive analysis of RCA, highlighting its properties, applications, and overall sustainability benefits to facilitate the comprehensive points of view of technology, ecology, and economics. This paper explores the manufacturing process of RCA, examines its mechanical and durability characteristics, and investigates its environmental impacts. Furthermore, it delves into the various applications of RCA, such as road construction materials, pavement bases, and concrete materials, considering their life cycle performance and economic considerations. This review reveals that there is a need for systemic data collection that could enable automated concrete mix design. The findings concerning various mix concrete designs suggest that increasing the 1% replacement level reduces the compressive strength by 0.1913% for coarse RCA and 0.2418% for fine RCA. The current critical research gaps are the durability of RCA concrete, feasibility analyses, and the implementation of treatment methods for RCA improvement. An effective life cycle assessment tool and digitalization technologies can be applied to enhance the circular economy, aligning with the United Nations’ sustainable development goals (UN-SDGs). The equivalent mortar volume method used to calculate the RCA concrete mix design, which can contain chemical additives, metakaolin, and fibers, needs further assessment. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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23 pages, 18755 KiB  
Article
Extended Material Recovery from Municipal Solid Waste Incinerator Bottom Ash Using Magnetic, Eddy Current, and Density Separations
by Ida Bagus Gede Sumbranang Adhiwiguna, Keshalinni Ramalingam, Karl-Heinz Becker, Alexander Khoury, Ragnar Warnecke and Rüdiger Deike
Recycling 2025, 10(1), 16; https://doi.org/10.3390/recycling10010016 - 24 Jan 2025
Viewed by 1190
Abstract
This research introduces an extended processing method for increasing the possibility of valorizing processed IBA (pr.IBA), which is currently only used as a construction material in landfill sites, considering its immense potential in valuable metal and mineral concentrations. Following a selective milling process, [...] Read more.
This research introduces an extended processing method for increasing the possibility of valorizing processed IBA (pr.IBA), which is currently only used as a construction material in landfill sites, considering its immense potential in valuable metal and mineral concentrations. Following a selective milling process, an extended material recovery sequence involving a magnetic, eddy current, and density separation sequence is developed. Based on the observations and outcomes explored in the present study, a substantially reliable and practical industrial approach is designed and tested to generate a cleaner mineral fraction and complementarily collect valuable metals from pr.IBA. Specifically, four enhanced valuable product streams can be anticipated, output mineral, high-magnetic, low-magnetic, and non-ferrous, which can be further utilized as alternative materials for cement clinker and concrete production coupled with iron, copper, and aluminum recovery in a conventional recycling operation. Therefore, in addition to introducing an additional perspective and moving one step closer to closing the waste management loop, this proposed method offers the opportunity to save primary materials and reduce carbon emissions by providing valuable alternative secondary resources. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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17 pages, 14354 KiB  
Article
Development of a Recycling Process for the Recovery of Gypsum Stone from Stockpile Material
by Jacob Fenner, Julius Luh, Bengi Yagmurlu and Daniel Goldmann
Recycling 2025, 10(1), 12; https://doi.org/10.3390/recycling10010012 - 16 Jan 2025
Viewed by 862
Abstract
Due to changes in the German government’s energy concept, the amount of gypsum produced in flue gas desulfurisation plants (FGD gypsum) will fall from 5 million tons per year to 1 million tons or less by 2038 at the latest. As of 2016, [...] Read more.
Due to changes in the German government’s energy concept, the amount of gypsum produced in flue gas desulfurisation plants (FGD gypsum) will fall from 5 million tons per year to 1 million tons or less by 2038 at the latest. As of 2016, FGD gypsum accounts for 55% of German gypsum mix. The resulting raw material gap must be closed through innovative recycling concepts, such as the processing of existing mine dumps. The process development aims to achieve a calcium sulfate dihydrate content of 85% and a reduction in the stockpile volume by 50%. The main components of the stockpiles are calcium sulfate in the form of gypsum stone as well as clay minerals and organic matter. Successful laboratory tests were transferred to a pilot scale jigging machine with dewatering screening. The process water is circulated throughout the entire process. The gypsum content in the heavy fraction is 76% when measured with ICP OES and 87% when measured via thermogravimetric methods. Furthermore, pilot-scale dry screening on the stockpile took place, and up to 1500 tons of material could be processed. Due to fluctuating weather conditions, the screening quality was subject to significant variations. Under optimal conditions, up to 60% of the feed could be recovered as gypsum stone; however, the screening process was nearly impossible during rain; therefore, a process combination of screening and a downstream jigging machine is recommended. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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13 pages, 7177 KiB  
Article
Preparation of an FA-Based Discoloration Material and Its Application in Jewelry Design
by Xiaomin Zhang, Xiangrui Gao, Yue Yuan, Guangqin Yang and Yanchen Li
Materials 2024, 17(22), 5628; https://doi.org/10.3390/ma17225628 - 18 Nov 2024
Viewed by 1060
Abstract
Fly ash (FA) is the main solid waste emitted from coal-fired power plants. Due to its high yield, low utilization rate, and occupation of a large amount of land, it exerts enormous pressure on the Earth’s environment. With the deepening of the concept [...] Read more.
Fly ash (FA) is the main solid waste emitted from coal-fired power plants. Due to its high yield, low utilization rate, and occupation of a large amount of land, it exerts enormous pressure on the Earth’s environment. With the deepening of the concept of sustainable development, exploring the reuse of industrial waste such as FA has become a key strategy. If FA can be combined with commonly used jewelry in people’s lives, it will be of great significance to promote the high-net-worth utilization of FA. Therefore, this study synthesized a fly-ash-based composite material with color-changing function and combined it with necklaces as the main material. In the first stage, after blending fly ash and slag, an alkaline activator with a total mass of 10% was added. When the proportion of fly ash was 60%, the compressive strength of the prepared fly-ash-based composite material reached 10.1 MPa. This was attributed to the reaction between sodium silicate in the alkaline activator and free CaO, MgO, and other substances in the fly ash to form hydrated silicate colloids, which solidify the fly ash and transform it into a complex three-dimensional network skeleton. In the second stage, a UV resistant coating with thermochromic function was obtained by blending acrylic resin, TiO2, and a thermosensitive color-changing agent. It was applied to the surface of fly-ash-based composite materials, and the results showed that as the content of the color-changing agent increased, the number of pores on the surface of the coating gradually decreased. When the content of color-changing agent was 10%, the prepared 10%FAB not only had good surface color but also had good thermal stability, UV absorption ability, superhydrophobicity, and mechanical properties. Therefore, 10%FAB was selected as the basic material for jewelry design. In the third stage, the traditional Chinese technique of “gold inlaid with jade” was utilized to develop jewelry applications for the FA composites. As such, 10%FAB was processed into necklaces, which not only had modern design aesthetics but also had good color-changing effects above 30 °C. And after a long period of UV aging experiments, the necklace did not show any wrinkles, bubbles, or other phenomena. Due to the excitation of TiO2 hole–electron pairs, the necklace’s UV absorption ability was further improved. This study demonstrates the potential application of industrial waste in decorative products, expands the high-end utilization of fly ash as a low-cost material, and provides new ideas for building a low-carbon lifestyle. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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20 pages, 12022 KiB  
Article
Study on the Effect of Basalt Fiber Content and Length on Mechanical Properties and Durability of Coal Gangue Concrete
by Zixin He, Xiao Zhao, Meichen Ye, Wei Zuo, Xiaoxiong Nie and Jianjun Zhao
Sustainability 2024, 16(21), 9310; https://doi.org/10.3390/su16219310 - 26 Oct 2024
Cited by 2 | Viewed by 1383
Abstract
The massive accumulation of coal gangue not only causes a waste of resources but also brings serious environmental pollution problems. To promote the utilization of coal gangue resources, mitigate environmental pollution from coal gangue, and address the shortage of natural aggregates, this study [...] Read more.
The massive accumulation of coal gangue not only causes a waste of resources but also brings serious environmental pollution problems. To promote the utilization of coal gangue resources, mitigate environmental pollution from coal gangue, and address the shortage of natural aggregates, this study investigates the use of coal gangue to replace coarse aggregate at a 40% replacement rate to prepare coal gangue concrete (CGC). The current research on the modification of gangue concrete by BF has been less often compared with the research on the effect of basalt fiber (BF) on the properties of ordinary concrete, so in this study, BF with different admixtures and lengths were added into CGC. Additionally, basalt fibers (BFs) of varying amounts and lengths were incorporated into CGC. The study explored the effects of BF on the tensile strength, splitting tensile strength, and flexural strength of CGC. It was found that the mechanical properties of CGC improved significantly when the BF dosage was 0.10–0.15% and the length was 18 mm. This is evidenced by an increase in the compressive strength of 3.94–5.11%, split tensile strength of 11.20–16.18%, and flexural strength of 8.23–12.97%. BF was able to refine pore space, prevent crack development, and bridge cracks in CGC. To further investigate the effect of BF on the long-term service performance of CGC, the effects of BF on the appearance, quality, and compressive strength of CGC in sulfate and freeze–thaw environments were examined. The results indicated that a BF dosage of 0.10–0.15% significantly enhanced the sulfate erosion resistance and freeze–thaw resistance of CGC. This is shown by a 36.76–46.90% reduction in the rate of loss of compressive strength of CGC under the freeze–thaw cycling and a 6.21–8.50% increase in the corrosion resistance factor of CGC under a sulfate attack. BF improved the pore structure and reduced seepage channels, thereby enhancing the durability of CGC. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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15 pages, 900 KiB  
Article
Evaluation of the Mechanical Behavior of Asphaltic Mixtures Utilizing Waste of the Processing of Iron Ore
by Antônio Carlos Rodrigues Guimarães, Marcio Leandro Alves de Arêdes, Carmen Dias Castro, Lisley Madeira Coelho and Sergio Neves Monteiro
Mining 2024, 4(4), 889-903; https://doi.org/10.3390/mining4040049 - 22 Oct 2024
Cited by 2 | Viewed by 1351
Abstract
Mineral extraction is an important operation for the economy of different countries and generates millions of tons of mining waste. In this context, and in association with the high demand for paving aggregates and the lack of raw materials for this purpose, the [...] Read more.
Mineral extraction is an important operation for the economy of different countries and generates millions of tons of mining waste. In this context, and in association with the high demand for paving aggregates and the lack of raw materials for this purpose, the feasibility of using iron ore processing waste has emerged as a promising alternative. This study evaluates the physical and mechanical behavior of asphalt mixtures incorporating waste from the company Samarco S.A., collected in Mariana-MG, to replace the fine aggregate in asphalt concrete mixtures, with a view to applications in the bearing layer of local traffic roads. Two mixtures, M2 and M3, containing 20% and 17% waste, respectively, were formulated and analyzed, compared to a reference mixture, M1. Evaluations were carried out using the Marshall method parameters, mechanical tests of resilience modulus, and fatigue life under controlled tension, as well as mechanistic analysis. Brazilian mechanistic–empirical design software (MeDiNa—v 1.5.0) contributed to this analysis. This analysis revealed that, for a traffic level of N = 5 × 106 (average traffic) on a local road, pavements containing the M1 and M3 mixtures had the same layer thicknesses (6.9 cm), as well as the same fatigue class, equal to 1. The pavement with the M2 mixture had the thickest asphalt layer (8.2 cm) and a lower fatigue class equal to 0. But if compared in terms of the percentage of cracked area over 10 years, it still offers ideal performance conditions compared to the M1 and M3 mixes. Thus, it can be considered feasible to replace fine aggregate with iron ore waste in asphalt concrete for use on local roads in the region without altering the bearing capacity of the pavement. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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18 pages, 5840 KiB  
Review
Accumulated Copper Tailing Solid Wastes with Specific Compositions Encourage Advances in Microbial Leaching
by Juan Zhang, Xiaojun Liu, Xinyue Du, Xin Wang, Yifan Zeng and Shukai Fan
Minerals 2024, 14(10), 1051; https://doi.org/10.3390/min14101051 - 20 Oct 2024
Cited by 1 | Viewed by 2573
Abstract
Against the backdrop of the increasing copper demand in a low-carbon economy, this work statistically forecasted the distribution of China’s copper tailings for the first time, and then characterized them as finely crushed and low-grade mining solid wastes containing copper mainly in the [...] Read more.
Against the backdrop of the increasing copper demand in a low-carbon economy, this work statistically forecasted the distribution of China’s copper tailings for the first time, and then characterized them as finely crushed and low-grade mining solid wastes containing copper mainly in the form of chalcopyrite, bornite, covelline, enargite and chalcocite based on available research data. China is the globally leading refined copper producer and consumer, where the typical commercial-scale bioleaching of copper tailings is conducted in the Dexing, Zijinshan and Jinchuan mining regions. And these leaching processes were compared in this study. Widely used chemolithoautotrophic and mesophilic bacteria are Acidithiobacillus, Leptospirillum, Acidiphilium, Alicyclobacillus and Thiobacillus with varied metal resistance. They can be used to treat copper sulfide tailings such as pyrite, chalcopyrite, enargite, chalcocite, bornite and covellite under sufficient dissolved oxygen from 1.5 to 4.1 mg/L and pH values ranging from 0.5 to 7.2. Moderate thermophiles (Acidithiobacillus caldus, Acidimicrobium, Acidiplasma, Ferroplasma and Sulfobacillus) and extreme thermophilic archaea (Acidianus, Metallosphaera, Sulfurococcus and Sulfolobus) are dominant in leaching systems with operating temperatures higher than 40 °C. However, these species are vulnerable to high pulp density and heavy metals. Heterotrophic Acidiphilium multivorum, Ferrimicrobium, Thermoplasma and fungi use organic carbon as energy to treat copper oxides (malachite, chrysocolla and azurite) and weathered sulfides (bornite, chalcocite, digenite and covellite) under a wide pH range and high pulp density. We also compared autotrophs in a planktonic state or biofilm to treat different metal sulfides using various sulfur-cycling enzymes involved in the polysulfide or thiosulfate pathways against fungi that produce various organic acids to chelate copper from oxides. Finally, we recommended a bioinformatic analysis of functional genes involved in Fe/S oxidization and C/N metabolism, as well as advanced representation that can create new possibilities for the development of high-efficiency leaching microorganisms and insight into the mechanisms of bioleaching desired metals from complex and low-grade copper tailings. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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15 pages, 1795 KiB  
Article
Enhancing Sewage Sludge Stabilization, Pathogen Removal, and Biomass Production through Indigenous Microalgae Promoting Growth: A Sustainable Approach for Sewage Sludge Treatment
by Hajer Ben Hamed, Antoine Debuigne, Hetty Kleinjan, Dominique Toye and Angélique Léonard
Recycling 2024, 9(5), 97; https://doi.org/10.3390/recycling9050097 - 12 Oct 2024
Cited by 1 | Viewed by 2279
Abstract
Sewage sludge (SS), a byproduct of wastewater treatment plants, poses significant environmental and health risks if not properly handled. Conventional approaches for SS stabilization often involve costly and energy-consuming processes. This study investigated the effect of promoting native microalgae growth in SS on [...] Read more.
Sewage sludge (SS), a byproduct of wastewater treatment plants, poses significant environmental and health risks if not properly handled. Conventional approaches for SS stabilization often involve costly and energy-consuming processes. This study investigated the effect of promoting native microalgae growth in SS on its stabilization, pathogen bacteria removal, and valuable biomass production. The effect on settleability, filterability, and extracellular polymeric substances (EPSs) was examined as well. Experiments were conducted in photobioreactors (PBRs) without O2 supply and CO2 release under controlled parameters. The results show a significant improvement in SS stabilization, with a reduction of volatile solids (VSs) by 47.55%. Additionally, fecal coliforms and E. coli were efficiently removed by 2.25 log and 6.72 log, respectively. Moreover, Salmonella spp. was not detected after 15 days of treatment. The settleability was improved by 71.42%. However, a worsening of the sludge filterability properties was observed, likely due to a decrease in floc size following the reduction of protein content in the tightly bound EPS fraction. Microalgae biomass production was 16.56 mg/L/day, with a mean biomass of 0.35 g/L at the end of the batch treatment, representing 10.35% of the total final biomass. These findings suggest that promoting native microalgal growth in SS could be sustainable and cost-effective for SS stabilization, microalgal biomass production, and the enhancement of sludge-settling characteristics, notwithstanding potential filtration-related considerations. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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17 pages, 7074 KiB  
Article
Upcycling Mill Scale and Aluminum Dross for Sustainable Materials Processing: Synthesis of Hercynite via Fe2O3-Al2O3-C Combustion
by Nuntaporn Kongkajun, Benya Cherdhirunkorn and Somyote Kongkarat
Recycling 2024, 9(5), 80; https://doi.org/10.3390/recycling9050080 - 17 Sep 2024
Cited by 2 | Viewed by 1470
Abstract
This study investigates the potential of utilizing industrial by-products—mill scale (MS) and aluminum dross (AD)—as sources of Fe2O3 and Al2O3, respectively, for hercynite (FeAl2O4) production. Through combustion of MS-AD-graphite systems at 1550 [...] Read more.
This study investigates the potential of utilizing industrial by-products—mill scale (MS) and aluminum dross (AD)—as sources of Fe2O3 and Al2O3, respectively, for hercynite (FeAl2O4) production. Through combustion of MS-AD-graphite systems at 1550 °C under air atmosphere, hercynite-based refractory materials were synthesized. Results confirm the viability of this upcycling approach for hercynite synthesis. During the formation of hercynite, the development of a dendritic structure can be observed, which subsequently fuses into a grain shape. XRD phase analysis using the Rietveld method revealed that the major components of the product with a C/O ratio of 1 were 85.11% FeAl2O4, 10.99% Al2O3, and 3.9% C. For the product with a C/O ratio of 2, the composition was 82.4% FeAl2O4, 13.0% Al2O3, and 4.6% C. The combustion of raw pellets with a C/O ratio of 1 at 1550 °C for 1 h in a normal air atmosphere is economically viable for producing hercynite, yielding 85.11 wt%. This approach presents a sustainable and eco-friendly alternative to using commercial raw materials, potentially eliminating the need for virgin alumina and iron ore. By repurposing waste materials from the steel and aluminum industries, this study contributes to the circular economy and aligns with the goal of zero waste. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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18 pages, 1012 KiB  
Review
Research Trends on Valorisation of Agricultural Waste Discharged from Production of Distilled Beverages and Their Implications for a “Three-Level Valorisation System”
by Kelly Stewart, Nik Willoughby and Shiwen Zhuang
Sustainability 2024, 16(16), 6847; https://doi.org/10.3390/su16166847 - 9 Aug 2024
Cited by 1 | Viewed by 1982
Abstract
The circular economy, driven by waste elimination, material circulation and nature regeneration, is crucial for business, people, and the environment. With the increasing demand for distilled beverages, managing agricultural waste like spent grains is paramount. While previous studies focused on individual beverages, investigating [...] Read more.
The circular economy, driven by waste elimination, material circulation and nature regeneration, is crucial for business, people, and the environment. With the increasing demand for distilled beverages, managing agricultural waste like spent grains is paramount. While previous studies focused on individual beverages, investigating technologies across different types of beverages has been overlooked. This paper provides a systematic review of agricultural waste valorisation over the past five years, focusing on four representative distilled beverages: whisk(e)y, tequila, baijiu and shochu. Research efforts have primarily focused on bioenergy production from whisk(e)y and tequila waste, whereas extracting functional substances is common for baijiu and shochu. Through integrating different technologies, a “Three-level Valorisation System” was proposed to enhance the translation of agricultural waste into value-added products like proteins. This system is directly relevant to the distilled beverage industry globally and applicable to associated industries such as biofuel and food production. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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15 pages, 6308 KiB  
Article
Silicon Kerf Recovery via Acid Leaching Followed by Melting at Elevated Temperatures
by Tinotenda Mubaiwa, Askh Garshol, Alexander Azarov and Jafar Safarian
Recycling 2024, 9(4), 66; https://doi.org/10.3390/recycling9040066 - 8 Aug 2024
Viewed by 1858
Abstract
The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an [...] Read more.
The aim of this work was to study the purification of silicon kerf loss waste (KLW) by a combination of single-acid leaching followed by inductive melting at high temperatures with an addition of fluidized bed reactor (FBR) silicon granules. The KLW indicated an average particle size (D50) of approximately 1.6 µm, and a BET surface area of 30.4 m2/g. Acid leaching by 1 M HCl indicated significant removal of impurities such as Ni (77%), Fe (91%) and P (75%). The combined two-stage treatment resulted in significant removal of the major impurities: Al (78%), Ni (79%), Ca (85%), P (92%) and Fe (99%). The general material loss during melting decreased with an increasing amount of FBR silicon granules which aided in the melting process and indicated better melting. It was observed that the melting behavior of the samples improved as the temperature increased, with complete melting being observed throughout the crucibles at the highest temperature (1800 °C) used, even without any additives. At lower temperatures (1600 °C–1700 °C) and lower FBR-Si (<30 wt.%) additions, the melting was incomplete, with patches of molten silicon and a lot of surface oxidation as confirmed by both visual observation and electron microscopy. In addition, it was indicated that more reactive and volatile elements (Ga, Mg and P) compared to silicon are partially removed in the melting process (51–87%), while the less reactive elements end up in the final silicon melt. It was concluded that if optimized, the combined treatment of single-acid leaching and inductive melting with the addition of granular FBR silicon has great potential for the recycling of KLW to solar cells and similar applications. Moreover, the application of higher melting temperatures is accompanied by a higher silicon yield of the process, and the involved mechanisms are presented. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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20 pages, 4111 KiB  
Article
Valorization of Fine-Fraction CDW in Binary Pozzolanic CDW/Bamboo Leaf Ash Mixtures for the Elaboration of New Ternary Low-Carbon Cement
by Javier Villar-Hernández, Ernesto Villar-Cociña, Holmer Savastano, Jr. and Moisés Frías Rojas
Resources 2024, 13(7), 100; https://doi.org/10.3390/resources13070100 - 19 Jul 2024
Viewed by 1467
Abstract
This paper presents the characterization of a binary mixture of construction and demolition waste (CDW) and bamboo leaf ash (BLAsh) calcined at 600 °C (novel mixture) and the study of its pozzolanic behavior. Different dosages in a pozzolan/Ca(OH)2 system were employed. The [...] Read more.
This paper presents the characterization of a binary mixture of construction and demolition waste (CDW) and bamboo leaf ash (BLAsh) calcined at 600 °C (novel mixture) and the study of its pozzolanic behavior. Different dosages in a pozzolan/Ca(OH)2 system were employed. The aim is the valorization of fine-fraction CDW that achieves a more reactive binary mixture and allows an adequate use of CDW as waste, as CDW is a material of limited use due to its low pozzolanic activity. The pozzolanic behavior of the mixture was analyzed using the conductometric method, which measures the electrical conductivity in the CDW + BLAsh/CH solution versus reaction time. With the application of a kinetic–diffusive mathematical model, the kinetic parameters of the pozzolanic reaction were quantified. This allowed a quantitative evaluation of the pozzolanic activity based on the values of these parameters. To validate these results, other experimental techniques were used: X-ray diffraction, thermogravimetry and scanning electron microscopy. Also, mechanical compressive strength assays were carried out. The results show an increase in the pozzolanic activity of binary mixes of CDW + BLAsh for all the dosages used in comparison to the pozzolanic activity of CDW alone. The quantitative assessment (kinetic parameters) shows that the binary mixture CDW50 + BLAsh50 is the most reactive (reaction rate constant of 7.88 × 10−1 h−1) and is superior to the mixtures CDW60 + BLAsh40 and CDW70 + BLAs30. Compressive strength tests show higher strength values for the ternary mixes (OPC + CDW + BLAsh) compared to the binary mixes (OPC + CDW). In view of the results, the binary blend of pozzolans CDW + BLAsh is suitable for the manufacture of future low-carbon ternary cements. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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26 pages, 17996 KiB  
Article
Critical Raw Materials Supply: Challenges and Potentialities to Exploit Rare Earth Elements from Siliceous Stones and Extractive Waste
by Xinyuan Zhao, Faten Khelifi, Marco Casale, Alessandro Cavallo, Elio Padoan, Ke Yang and Giovanna Antonella Dino
Resources 2024, 13(7), 97; https://doi.org/10.3390/resources13070097 - 15 Jul 2024
Cited by 4 | Viewed by 3236
Abstract
Critical raw materials (CRMs) supply is a challenge that EU countries have to face, with many thinking about domestic procurement from natural ore deposits and anthropogenic deposits (landfills and extractive waste facilities). The present research focuses on the possibilities linked to the supply [...] Read more.
Critical raw materials (CRMs) supply is a challenge that EU countries have to face, with many thinking about domestic procurement from natural ore deposits and anthropogenic deposits (landfills and extractive waste facilities). The present research focuses on the possibilities linked to the supply of CRMs and the potential for exploiting rare earth elements (REEs), investigating a large variety of extractive waste and siliceous rocks in the Piedmont region (Northern Italy). Indeed, the recovery of REEs from the extractive waste (EW) of siliceous quarries and other siliceous ore deposits can be a valuable way to reduce supply chain risks. Starting with a review of the literature on mining activities in Piedmont and continuing with the sampling and geochemical, mineralogical, petrographic, and environmental characterization of EW facilities connected to siliceous dimension stones, of kaolinitic gneiss ore deposits, and of soils present near the investigated areas, this study shows that the degree of REEs enrichment differs depending on the sampling area (soil or EW) and lithology. The concentration of REEs in the EW at some sampling sites fulfils the indicators of industrial-grade and industrial recovery; the high cumulative production and potential market values of EW and the positive recovery effects through proven methodologies indicate a viable prospect of REE recovery from EW. However, REE recovery industrialization faces challenges such as the difficulty in achieving efficient large-scale recovery due to large regional differences in REE abundance, the mismatch between potential market value and waste annual production, etc. Nonetheless, in the future, EW from dimension stone quarries could be differentially studied and reused based on the enrichment and distribution characteristics of trace elements. The present paper shows investigation procedures undertaken to determine both CRMs potentialities and environmental issues (on the basis of literature data employed to select the more-promising areas and on sampling and characterization activities in the selected areas), together with procedures to determine the waste quantities and tentative economic values of REEs present in the investigated areas. This approach, tested on a large area (Piedmont region), is replicable and applicable to other similar case studies (at EU and non-EU levels) and offers decision makers the possibility to acquire a general overview of the potential available resources in order to decide whether and where to concentrate efforts (including economic ones) in a more detailed study to evaluate the exploitable anthropogenic deposits. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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19 pages, 5324 KiB  
Article
Utilization of Natural Soils as a Remediation Method for Electric Arc Furnace and Ladle Slags
by Bilal Korkmaz and Asli Yalcin Dayioglu
Sustainability 2024, 16(12), 5244; https://doi.org/10.3390/su16125244 - 20 Jun 2024
Cited by 3 | Viewed by 1600
Abstract
Steel slags are solid residual materials formed as by-products throughout the process of steel production within the steelmaking industry. These wastes have good physical properties such as high stiffness and friction angle for use as road fill materials or in geotechnical applications. However, [...] Read more.
Steel slags are solid residual materials formed as by-products throughout the process of steel production within the steelmaking industry. These wastes have good physical properties such as high stiffness and friction angle for use as road fill materials or in geotechnical applications. However, the presence of heavy metals and high alkalinity levels constitute significant environmental hazards and set limitations on using slags in engineering applications. While there have been investigations into the mechanical characteristics of steel slags, research on assessing potential harm when utilizing the materials in engineering applications is rare. This study examines the mitigation methods to address the environmental problems associated with steel slags. To do this, two different steel slags with different production techniques were treated with soils of different properties such as fine and coarse sand, bentonite, kaolin, and natural clay. The pH and electrical conductivity (EC) values of pure steel slags were determined using the water leach test (WLT). Variations in pH and EC values of steel slags subjected to treatment were evaluated through both WLT and sequential water leach (SWLT) tests. As a result, the high strength, stiffness, and drainage capability of EAF and LS steel slags make these materials suitable for road filling. This is further backed by their soaked and unsoaked CBR values. During the water leach tests, notable decreases in pH were observed with a 60% natural clay (NC) solution, resulting in a decrease of 1.2 and 0.7 in EAF and LS, respectively. The addition of sand had a negligible impact on pH due to its inert characteristics. Moreover, in sequential water leach tests, the most significant decrease in pH was observed with NC (with a reduction of 2.0 points for EAF and 0.9 points for LS) through enhanced ion exchange and extended periods of dilution and buffering. Also, the use of NC resulted in substantial decreases in EC for EAF and LS, with reductions of 77% and 81%, respectively. Moreover, heavy metal concentrations in leachate waters from pure steel slags have been detected, and the effect of treatment on aluminum and iron concentrations has been determined. The results indicate that the use of natural soil significantly drops the pH and lowers the trace metal concentrations within the leachate. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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19 pages, 4295 KiB  
Article
Geopolymerization of Recycled Glass Waste: A Sustainable Solution for a Lightweight and Fire-Resistant Material
by Marios Valanides, Konstantinos Aivaliotis, Konstantina Oikonomopoulou, Alexandros Fikardos, Pericles Savva, Konstantinos Sakkas and Demetris Nicolaides
Recycling 2024, 9(1), 16; https://doi.org/10.3390/recycling9010016 - 7 Feb 2024
Cited by 6 | Viewed by 3568
Abstract
Glass is considered a sustainable material with achievable recovery rates within the EU. However, there are limited data available for construction glass waste management. Furthermore, glass is a heavy material, and considering the geographical limitations of Cyprus, the transportation trading cost within the [...] Read more.
Glass is considered a sustainable material with achievable recovery rates within the EU. However, there are limited data available for construction glass waste management. Furthermore, glass is a heavy material, and considering the geographical limitations of Cyprus, the transportation trading cost within the EU is extremely high. Therefore, another method for utilizing this by-product should be developed. The aim of this research is to investigate the production of a low-cost, lightweight and fireproof material able to retain its structural integrity, using the geopolymerization method with the incorporation of randomly collected construction glass waste. The glass waste was initially processed in a Los Angeles abrasion machine and then through a Micro-Deval apparatus in order to be converted to a fine powder. Mechanical (compressive and flexural strength), physical (setting time and water absorption) and thermal properties (thermal conductivity) were investigated. The fire-resistant materials presented densities averaging 450 kg/m3 with a range of compressive strengths of 0.5 to 3 MPa. Additionally, a techno-economic analysis was conducted to evaluate the viability of the adopted material. Based on the results, the final geopolymer product has the potential to be utilized as a fire resistance material, preventing yielding or spalling. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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16 pages, 6752 KiB  
Article
Effect of Limestone Powder Mixing Methods on the Performance of Mass Concrete
by Lele Zhao, Tingshu He, Mengdie Niu, Xiulong Chang, Lei Wang and Yan Wang
Materials 2024, 17(3), 617; https://doi.org/10.3390/ma17030617 - 27 Jan 2024
Cited by 3 | Viewed by 1442
Abstract
Using limestone powder (LP), the by-product of manufactured sand, to replace part of fly ash (FA) or manufactured sand could not only turn waste into treasure and decrease the price of concrete, but could also enhance the performance of concrete and reduce environmental [...] Read more.
Using limestone powder (LP), the by-product of manufactured sand, to replace part of fly ash (FA) or manufactured sand could not only turn waste into treasure and decrease the price of concrete, but could also enhance the performance of concrete and reduce environmental pollution. However, the impact of various LP incorporation methods on the performance of mass concrete was inconsistent. In this paper, the effects of LP on the workability, compressive strength, constrained expansion rate, hydration temperature and impermeability of mass concrete were studied by replacing FA or manufactured sand alone and replacing FA and manufactured sand simultaneously. The results showed that the impact of LP on the performance of mass concrete was equal when it replaced FA alone and FA and manufactured sand at the same time. When the replacement amount was 20%, the workability, expansibility and early strength of concrete were improved, but the later strength and impermeability were slightly reduced. The workability, compressive strength, expansibility and impermeability of mass concrete were improved when manufactured sand was replaced alone, and the optimal dosage was 10%. The LP, moreover, reduced the hydration temperature peak of concrete in three kinds of mixing methods, but the temperature peak appeared earlier. At lower dosages, LP optimized pore structure and promoted the early hydration of cement through filler effects and nucleation effects. When LP replaced manufactured sand, the microstructure of concrete was more dense, so the replacement of manufactured sand had a better effect on the improvement of concrete properties. A reference value for the use of LP in mass concrete is provided in this study. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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21 pages, 9465 KiB  
Article
Removal of Fe3+ Ions from Aqueous Solutions by Adsorption on Natural Eco-Friendly Brazilian Palygorskites
by Antonieta Middea, Luciana dos Santos Spinelli, Fernando Gomes de Souza Junior, Thais de Lima Alves Pinheiro Fernandes, Luiz Carlos de Lima, Vitoria Maria Tupinamba Souza Barthem, Otávio da Fonseca Martins Gomes and Reiner Neumann
Mining 2024, 4(1), 37-57; https://doi.org/10.3390/mining4010004 - 19 Jan 2024
Viewed by 1849
Abstract
This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray [...] Read more.
This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), size distribution measurements, density measurement by He pycnometry, superconducting quantum interference device (SQUID) magnetometry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), zeta potential measurement, hydrophobicity determination by contact angle, Brunauer–Emmett–Teller surface area analysis (BET technique) and atomic force microscopy (AFM). Batch experiments were performed in function of process parameters such as contact time and initial concentration of Fe3+. The natural palygorskites (Palys) had excellent performance for the removal of Fe3+ from aqueous solutions by adsorption (around 60 mg/g), and the Langmuir is supposedly the best model fitted the experimental data. Full article
(This article belongs to the Topic Sustainable Recycling and Reuse of Industrial By-Products or Waste from Geo-Resource Exploitation)
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