| 1. |
- Morozovska, Kateryna, et al.
(författare)
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Trade-offs of wind power production: A study on the environmental implications of raw materials mining in the life cycle of wind turbines
- 2024
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 460
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Tidskriftsartikel (refereegranskat)abstract
- The energy demand in Sweden is increasing due to the growing electrification, and to meet this need, the generation must be expanded. Wind power generation is a very attractive renewable power production alternative for Sweden because of the favorable weather conditions. Research looks at how much wind energy may be deemed sustainable. Increased energy demand puts pressure on the government and industry to build more wind farms and, as a result, produce more wind turbines. Raw materials are necessary for wind turbines to provide a secure transition to green energy technologies. To meet these demands, the materials from various countries should efficiently contribute towards the Sustainable Development Goals (SDGs). This paper gathers information about raw resources from diverse nations worldwide. All materials are mapped to the country where they are produced using social science criteria. A few nations are chosen based on a sample approach for further analysis, and the implications of mining operations are investigated. Finally, the direct and indirect effects of the SDGs are considered. Based on the data gathered, recommendations and considerations are given to avoid or mitigate the repercussions of raw materials mining and make wind power generation more socially and environmentally sustainable.
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| 2. |
- Malovanyy, Myroslav, et al.
(författare)
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Disposal of pine wood waste by pelleting with sulphate soap binder
- 2024
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Ingår i: Pollack Periodica. - Poland. - 1788-1994 .- 1788-3911. ; 19:1, s. 47-52
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Tidskriftsartikel (refereegranskat)abstract
- Promising method for disposal the pine wood waste through extrusion pelleting using sulphate soap as a natural binder is considered in the article. Prior to pelleting, the wood waste requires drying to a water content of no more than 10%. Analysis of pine wood waste drying in filtration mode yielded optimal parameters: A 20 mm layer thickness, temperature of 135 °C, and drying time of 3,900 s. The optimal content of sulphate soap binder was determined to be about 20%, resulting in reduced coke residue, increased volatile components, higher calorific value, and enhanced static strength. This binder facilitates formation of pellets at lower pressures, increases calorific value, and acts as a lubricant, reducing friction and associated energy costs.
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| 3. |
- Di Donna, Alice, et al.
(författare)
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The contribution of swelling to self-sealing of claystone studied through x-ray tomography
- 2022
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Ingår i: Physics and Chemistry of the Earth. - : Elsevier BV. - 1474-7065. ; 127
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Tidskriftsartikel (refereegranskat)abstract
- Many countries, as among others France, Belgium and Switzerland, are facing the issue of finding a proper solution to store radioactive waste coming from nuclear power plants. The possibility to store them in underground tunnels is largely considered and investigated. In France, Andra (Agence Nationale pour la gestion des Déchets RAdioactifs) selected the Callovo-Oxfordian clay rock situated in the Meuse/Haute Marne site between 400 and 600 m depth as possible host rock deposit. The excavation of the storage tunnels is expected to create a fractured zone around galleries. The factures will be then gradually re-saturated by the underground water coming from the surrounding rock and they are expected to self-seal in contact with water, thanks to the swelling potential of COx. The capacity of self-sealing, i.e. closing of fractures after water contact and possibly restoring of permeability, is thus of primary interest for the safety of the storage system with respect to water, gas and solutes transport. The physical mechanisms driving this phenomenon are mainly the swelling and de-structuration of the clay matrix present in the claystone. In this work, the self-sealing response of COx was investigated through x-ray tomography at multi-micrometre and sub-micrometre voxel size. The objective was to study the influence of mineralogy, size of the discontinuity, hydraulic paths, mutual orientation of the bedding plane and fractures. The size of the discontinuity is of primary importance in determining the percentage of closure. Fractures parallel to the bedding plane are more likely to seal as swelling is anisotropic and occurs mainly perpendicular to the bedding plane. The main novelty is represented by the direct and local observation of the physical process of self-sealing down to a scale lower than 1 μm.
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| 4. |
- Hildor, Fredrik, 1992
(författare)
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Steel converter slag as an oxygen carrier
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Thermal conversion of fuels can be used to produce heat and power in addition to chemicals. In order to be aligned with climate targets, it is necessary that such systems do not emit carbon dioxide to the atmosphere. Carbon capture and storage (CCS) can be used together with fuel conversion systems to prevent CO2 from entering the atmosphere. If CCS is used together with biomass-based fuels, it is possible to achieve a net-flow of carbon dioxide out of the atmosphere, so called negative emissions. Chemical looping technologies for combustion (CLC) and gasification (CLG) are technologies which can be used for heat, power and chemical production with no or low penalties for carbon capture. In any chemical looping applications, a functional oxygen carrier is essential. The oxygen carrier is normally a metal oxide based material that can transport oxygen from one reactor to another. However, when fuel is introduced into the system, ash can react with the oxygen carrier and decrease its operational lifespan, especially reactive ash from biomass and low-grade fuels. Therefore, there is growing interest in low-cost oxygen carriers that can contribute to making the process economically feasible. Low-cost oxygen carriers can be obtained from ores or as byproducts of the steel industry. Of particular interest is steel converter slag, which is also known as Linz-Donawitz (LD) slag. LD slag is generated in significant amounts, contains sufficient amount of iron oxide (that can act as an oxygen carrier) and available at a low cost. This work presents a comprehensive overview of the chemistry and behavior of LD slag when it is implemented as an oxygen carrier in chemical-looping applications. The material has been investigated in laboratory reactors, in addition to pilot and semi-industrial units, and LD slags interactions with different fuel components, ash, alkali salts, sulfur and tars have been investigated. It is concluded from this work that LD slag can be viable as material for both CLC and CLG processes with biomass. In contrast to other bed materials, such as silica sand or the commonly investigated iron-based oxygen carrier ilmenite, the slag has limited reactivity with reactive alkali components. This results in more alkali being available in the gas phase, which is beneficial for tar cracking and for the gasification rate of the solid char. The high content of calcium in the LD slag is also favorable in terms of gasification and ash interactions. Calcium oxide catalyzes both the water-gas shift reaction and is catalytic towards tar cracking. A high level of calcium also increases the melting points of both the K-Ca-P and K-Ca-Si matrixes. However, the structural integrity of the material is lower compared to, for example, ilmenite, resulting in more fines being generated during the process. Overall, LD slag is a potential oxygen carrier that is suitable for chemical-looping processes that utilize low-grade fuels.
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| 5. |
- Moldenhauer, Patrick, 1983, et al.
(författare)
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Avoiding CO2 capture effort and cost for negative CO2 emissions using industrial waste in chemical-looping combustion/gasification of biomass
- 2020
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Ingår i: Mitigation and Adaptation Strategies for Global Change. - : Springer Science and Business Media LLC. - 1381-2386 .- 1573-1596. ; 25:1, s. 1-24
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-looping combustion (CLC) is a combustion process with inherent separation of carbon dioxide (CO2), which is achieved by oxidizing the fuel with a solid oxygen carrier rather than with air. As fuel and combustion air are never mixed, no gas separation is necessary and, consequently, there is no direct cost or energy penalty for the separation of gases. The most common form of design of chemical-looping combustion systems uses circulating fluidized beds, which is an established and widely spread technology. Experiments were conducted in two different laboratory-scale CLC reactors with continuous fuel feeding and nominal fuel inputs of 300 Wth and 10 kWth, respectively. As an oxygen carrier material, ground steel converter slag from the Linz–Donawitz process was used. This material is the second largest flow in an integrated steel mill and it is available in huge quantities, for which there is currently limited demand. Steel converter slag consists mainly of oxides of calcium (Ca), magnesium (Mg), iron (Fe), silicon (Si), and manganese (Mn). In the 300 W unit, chemical-looping combustion experiments were conducted with model fuels syngas (50 vol% hydrogen (H2) in carbon monoxide (CO)) and methane (CH4) at varied reactor temperature, fuel input, and oxygen-carrier circulation. Further, the ability of the oxygen-carrier material to release oxygen to the gas phase was investigated. In the 10 kW unit, the fuels used for combustion tests were steam-exploded pellets and wood char. The purpose of these experiments was to study more realistic biomass fuels and to assess the lifetime of the slag when employed as oxygen carrier. In addition, chemical-looping gasification was investigated in the 10 kW unit using both steam-exploded pellets and regular wood pellets as fuels. In the 300 W unit, up to 99.9% of syngas conversion was achieved at 280 kg/MWth and 900 °C, while the highest conversion achieved with methane was 60% at 280 kg/MWth and 950 °C. The material’s ability to release oxygen to the gas phase, i.e., CLOU property, was developed during the initial hours with fuel operation and the activated material released 1–2 vol% of O2 into a flow of argon between 850 and 950 °C. The material’s initial low density decreased somewhat during CLC operation. In the 10 kW, CO2 yields of 75–82% were achieved with all three fuels tested in CLC conditions, while carbon leakage was very low in most cases, i.e., below 1%. With wood char as fuel, at a fuel input of 1.8 kWth, a CO2 yield of 92% could be achieved. The carbon fraction of C2-species was usually below 2.5% and no C3-species were detected. During chemical-looping gasification investigation a raw gas was produced that contained mostly H2. The oxygen carrier lifetime was estimated to be about 110–170 h. However, due to its high availability and potentially low cost, this type of slag could be suitable for large-scale operation. The study also includes a discussion on the potential advantages of this technology over other technologies available for Bio-Energy Carbon Capture and Storage, BECCS. Furthermore, the paper calls for the use of adequate policy instruments to foster the development of this kind of technologies, with great potential for cost reduction but presently without commercial application because of lack of incentives.
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| 6. |
- Ren, Kaipeng, et al.
(författare)
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Evaluating metal constraints for photovoltaics : Perspectives from China’s PV development
- 2021
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 282
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Tidskriftsartikel (refereegranskat)abstract
- Chinese PV industry can be expected to grow rapidly of until 2050, driven by ongoing decarbonization of the energy mix. Such large-scale deployments generate significant increases in metal demand that may induce resource dilemmas. In this study, dynamic material flow analysis is combined with scenario analysis to estimate future metal demand from Chinese PV industry and complemented by a supply risk assessment. It is found that the maximum annual copper and silver demand up to 2050 equals 79.6% and 58.5% of China’s annual production in 2019. Similarly, the baseline scenario projects maximum annual demand of Tellurium and Indium corresponding to 598.1% and 161.8% of China’s annual production in 2019. Cumulative base metal demand by 2050 for China’s PV sector is 17.3–22.8 times that of in 2018, while cumulative silver demand increases by 4.5–6 times from 2018 to 2050. In the baseline scenario, cumulative byproduct metal demand by 2050 is 14–27.3 times larger than in 2018. High annual and cumulative supply pressures indicate not only the general scarcity of base, precious, and byproduct metals but also highlights the importance of building stable trade relationships for future PV developments in China. Two different measures are identified and assessed for reducing short- and long-term supply risks. Prolonging the lifetime from 25 to 30 years can achieve a cumulative metal conservation of 6.7–24.2%, while shorter lifetime will give rise to secondary supply if recycling technologies are implemented. A clean energy shift indicates that metal availability will become an important perspective for assessing energy security, implying that resource constraints should be considered in different planning levels for renewable energy developments. Strong interconnections between energy and metal supply chains indicate that coordination and holistic nexus views are required for achieving simultaneous sustainability in both systems.
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| 7. |
- Sanchez Llancan, Felipe, et al.
(författare)
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Assessing the Environmental Impact of Mining - Holistic Data-Driven Approach for Quarrying Operations
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Quarries can produce a series of environmental impacts, e.g. ground vibration, noise, dust, and air emissions. The DigiEcoQuarry project (DEQ), in which the research presented in this paper is framed, aims to digitalise quarries in Europe, enhancing their economic and environmental performance, safety aspects, and social acceptance. From the implementation of an integrated IoT system, a large amount of operational data is generated and collected, including, for example, drilling and blasting parameters, real-time positioning of the mobile fleet, driving speed, cycle times, distances, weather conditions (i.e. precipitation and sunshine time), and materials flow (extracted, transported, processed). It is expected that the analysis of this information, besides facilitating operational efficiency, allows the prediction of immediate and later environmental impacts with more frequency than traditional methods. Consequently, mitigation strategies can be improved, opening also the opportunity to adjust operational parameters to achieve a broader global efficiency. In this context, the objective of this paper is to provide a comprehensive review and analysis of the most frequent and relevant environmental aspects of quarries, with a focus on the local effects. From the evaluation conducted, these aspects were linked to certain characteristics and conditions that can be present in quarrying operations, providing a guide to identifying the main environmental challenges for different types of quarries. Moreover, this framework was applied to the sites participating in the DEQ project, revealing the major environmental concerns in each case. Finally, air emissions, dust emissions, and noise pollution were identified as the impacts with the highest potential for complementary estimation through machine learning or similar techniques based on operational data.
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| 8. |
- Wang, Benxin, 1991, et al.
(författare)
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Fracture characteristics and the damage constitutive model of 3D printing undulating joint samples based on DIC
- 2022
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Ingår i: Gongcheng Kexue Xuebao/Chinese Journal of Engineering. - 2095-9389. ; 44:12, s. 2029-2039
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Tidskriftsartikel (refereegranskat)abstract
- Due to the influence of geological structures, various forms of joint structural planes are present in rock mass engineering. The undulating structural planes, such as a torsional fold surface, are unique geological structures. These structures affect the stability of rock masses and cause potential hazards to rock mass engineering. Because of their shape complexity, the research on the fracture and damage constitutive law of rock mass with undulating joints is not thoroughly conducted. Undulating joints with various dip angles were fabricated using three-dimensional printing technology. The uniaxial compression test and digital image correlation (DIC) technology were used to study the mechanical and fracture characteristics of undulating joint specimens. Based on the principle of fracture mechanics, an idea was proposed to use the DIC displacement field for solving the stress intensity factor (SIF: type one KI and type two KII) at the joint tips and to study the damage constitutive law. The results show that the upper limit of undulating joint damage to specimens is determined with 46.6% through the minimum strength analysis. The sensitivity of uniaxial strength to a joint dip angle of undulating joint specimen is greater than that of a straight joint specimen. The fracture initiation occurs near peak stress. The fracture process can be divided into the initiation and synchronous penetration of microcracks on the fracture path. Additionally, the fracture mode shows a combination of multiple tension and shear fractures. The SIF increases with loading at the prepeak stage, and the cracks propagate in shear fracture at the joint left and right tips in the postpeak stage because KII>KI under the same stress. The undulating joint damage to the specimen with the dip angle is in a sinusoidal curve form. The relationships between the total damage coupled by joint and load with strain are all “S” curves.
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| 9. |
- Wang, Benxin, 1991, et al.
(författare)
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Study on mechanical and fracture characteristics of rock-like specimens with rough non-persistent joints by YADE DEM simulation
- 2023
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Ingår i: Computers and Geotechnics. - : Elsevier BV. - 0266-352X .- 1873-7633. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Rough non-persistent joints exist widely in natural rock mass. The roughness of joints influences its mechanical and fracture characteristics. However, the research on rough non-persistent jointed rock mass is inadequate. To investigate the effects of joint angle, rock bridge angle and roughness of rough non-persistent joints, the rough non-persistent joints were truncated and their JRC was calibrated based on the Barton typical roughness profiles. A series of DEM numerical uniaxial compression tests were conducted based on the laboratory tests of rock-like specimens with 3D printed non-persistent joints. By the investigation of mechanical behaviour, crack coalescence types, crack evolution law, fracture modes presented by the strain field, and micro-fracture mechanism revealed by the displacement vectors, it was verified that YADE is suitable to simulate the fracture of rough non-persistent jointed specimens; the six types of coalescence of rough non-persistent joints were concluded, and the relation between micro-crack and macro-fracture was established by the four types of micro-cracks causing macro-fractures.
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| 10. |
- Wang, Benxin, 1991, et al.
(författare)
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The Strength and Macro-mesoscopic Fracture Characteristics of 3D-printed Rock-like Specimens with Internal Parallel Joints
- 2022
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Ingår i: Geotechnical and Geological Engineering. - : Springer Science and Business Media LLC. - 0960-3182 .- 1573-1529. ; 40:6, s. 3307-3324
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Tidskriftsartikel (refereegranskat)abstract
- The internal parallel joints weaken the rock mass and they are more difficult to be studied than the exposed joints. The intact specimen and internal parallel four joints (IPFJ) specimen were prepared by 3D printing for the uniaxial compression. According to the macro-mechanical parameters of the intact specimen, the apparent fractures, and internal 3D fracture modes obtained by computerized tomography technology, the Particle Flow Code 3D (PFC3D) was used to study the strength properties, 3D fracture modes, and macro-meso evolution mechanism of specimens with IPFJ under uniaxial compression. It was found that the apparent macro fractures are initiated at the yield point of about 90% of the peak stress in 3D similar to 2D. However, the stress of inner initial fracture is approximately 30% of the peak stress due to the strike discontinuity of joints in 3D. The stress intensity factors at the inner and outer edges of the joints are influenced by the adjacent joints leading to four fracture modes. Finally, a small number of tensile micro-cracks on the propagation path cause a large number of shear micro-cracks based on the force chain analysis.
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| 11. |
- Adolfsson, Lars, 1955-
(författare)
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What keeps a shoulder stable - Is there an ideal method for anterior stabilisation?
- 2024
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Ingår i: Shoulder & Elbow. - : Sage Publications. - 1758-5732 .- 1758-5740. ; 16:1, s. 4-7
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The gleno-humeral joint is by far the most mobile in the human body but also afflicted by dislocations, predominantly anterior. Surgical stabilisation is often successful but failures not uncommon. The following review describes potential causes of failure and highlights the need of adapting surgical methods to pathomorphology.
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| 12. |
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| 13. |
- Andrén, Anna, et al.
(författare)
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Degradation of the Reinforcing Effect of Shotcrete : Freeze-Thaw Tests on Shotcrete-Rock Panels
- 2020
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Ingår i: The Electronic journal of geotechnical engineering. - : Mete Öner. - 1089-3032 .- 1089-3032. ; 25:1, s. 1-30
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Tidskriftsartikel (refereegranskat)abstract
- In rock tunnels in regions with colder climates, the load-bearing structure, including the rock and the reinforcing elements, is exposed to repeated destructive freezing and thawing cycles during the winter. If water accumulates in cracks or in the interface between rock and shotcrete, frost shattering may occur. If there is adequate adhesion between the rock and shotcrete, degradation of the shotcrete as a reinforcement element due to frost shattering should not present a problem. However, if adhesion is poor, a small void will form between the rock and the shotcrete where water can accumulate. If the water in these voids is subjected to freeze-thaw cycles, ice will develop, thus exerting pressure on the interface and causing the shotcrete to crack and degrade. In tunnel sections with complex water conditions, for example, relatively water-bearing open joints and weak zones, the adhesion of the shotcrete and its stability and reinforcing effect may be strongly affected when exposed to freezing temperatures. This article describes a laboratory study that comprised freeze-thaw tests on shotcreterock panels with the objective of studying how water migration affects the growth of ice and the ice pressure in the shotcrete-rock interface to better understand the degradation of the reinforcing effect of shotcrete
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| 14. |
- Andrén, Anna, et al.
(författare)
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Evaluation of a laboratory model test using field measurements of frost penetration in railway tunnels
- 2022
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Ingår i: Cold Regions Science and Technology. - : Elsevier. - 0165-232X .- 1872-7441. ; 204
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Tidskriftsartikel (refereegranskat)abstract
- Despite extensive grouting efforts to prevent water from leaking into tunnels, water seepages remain. When exposed to freezing temperatures, ice formations occur. During the winter, the Swedish Transport Administration's railway tunnels are affected by major problems caused by ice, such as icicles from roof and walls, ice loads on installations, ice-covered tracks and roads, etc. To ensure safety and prevent traffic disruptions, many tunnels require extensive maintenance. Improved knowledge about frost penetration in tunnels is required to reduce maintenance of the tunnels. Frost insulated drain mats are often used at leakage spots to prevent ice formation along the tunnels. To find out which parts of a tunnel are exposed to freezing temperatures, the University of Gävle and the Royal Institute of Technology in Stockholm conducted a laboratory model test on behalf of the Swedish National Rail Administration (now the Swedish Transport Administration). The laboratory model test aimed to find a method to determine the expected temperature conditions along a tunnel to decide which parts of the tunnel require frost insulation to protect the drainage system from freezing and prevent ice formation. To evaluate the laboratory model test, the Swedish Transport Administration in collaboration with Luleå University of Technology have performed field surveys in two Swedish railway tunnels. The field measurements involved monitoring temperatures in air, rock surfaces and rock mass, as well as measuring wind direction, wind and air velocity and air pressure. The measurements in the tunnels show that the frost penetrates further into the tunnels than was expected from the laboratory model test, which was based on a completely uninsulated tunnel. Frost insulated drains do not only prevent the cold air from reaching the rock mass, but also prevent the rock from emitting geothermal heat that warms up the cold tunnel air. Consequently, the frost penetrates further into the tunnel than it would do if the heat from the rock mass was allowed to warm up the outside air on its way into the tunnel. The number of frost insulated drains and how much of the tunnel walls and roof are covered thereby affect the length of the frost penetration.
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| 15. |
- Andrén, Anna, et al.
(författare)
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Field Observations of Water and Ice Problems in Railway Tunnels from a Maintenance Perspective
- 2023
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Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 13:1, s. 11-54
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Tidskriftsartikel (refereegranskat)abstract
- During the winter season, ice causes major problems in many Swedish railway tunnels. Ice, rock and shotcrete in the roof and on the walls may come loose and fall down, installations and cables can break due to ice loads and the tracks can become covered with ice. To maintain safety and prevent traffic disturbances, many tunnels require frequent maintenance. The removal of ice, loose rock and shotcrete is expensive and potentially risky work for the maintenance workers. To reduce maintenance costs, it is important to improve our knowledge of frost penetration inside tunnels and investigate the effect of ice pressure and frost shattering on loadbearing constructions. The aim of this investigation was to gather information about the problems caused by water leakage and its effect on the degradation of a rock tunnel when subjected to freezing temperatures. There are many factors that determine whether frost or ice formations will appear in tunnels. To collect information on ice formation problems, field observations were undertaken in five of Sweden’s railway tunnels between autumn 2004 and summer 2005. For one of the tunnels, follow-up observations also took place in March during the years 2005, 2006 and 2007.
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| 16. |
- Andrén, Anna, et al.
(författare)
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Temperature Flows in Railway Tunnels : Field Measurements of Frost Penetration
- 2020
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Ingår i: Journal of Earth Sciences and Geotechnical Engineering. - : Scientific Press International Limited. - 1792-9040 .- 1792-9660. ; 10:5, s. 161-194
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Tidskriftsartikel (refereegranskat)abstract
- Even though extensive pre-grouting is carried out during the construction of tunnels, certain leakages and drips remain. These remaining leakages are remedied by a combination of post-injection and drainage measures with, for example, frost insulated drain mats, whose function is to prevent the cold tunnel air from reaching a leakage spot and causing water to freeze. Despite these measures, some water may still enter the tunnels and cause problems during winter with ice formations and frost shattering. Icicles, ice pillars and ice-covered roads and railway tracks require constant maintenance. If ice occurs in the fracture network close to the tunnel contour or in the interface between the rock and shotcrete, it can cause degradation of the load-bearing capacity of the tunnel and fall-outs of both materials. In tunnel sections with water leakage problems it is common to protect the load-bearing structure from freezing with insulated drainage systems. To determine where along the tunnel efforts must be made to prevent ice formation, the temperature conditions of tunnels must be investigated. This article presents parts of the results from field measurements in two Swedish railway tunnels. The measurements involves monitoring of air and rock temperatures, air pressure and air velocity.
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| 17. |
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| 18. |
- Asimi Neisiani, Ali, et al.
(författare)
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Biodegradable acids for pyrite depression and green flotation separation–an overview
- 2024
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Ingår i: Critical reviews in biotechnology. - : Taylor & Francis. - 0738-8551 .- 1549-7801. ; 44:6, s. 1226-1240
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Forskningsöversikt (refereegranskat)abstract
- Exponential increasing demands for base metals have made meaningful processing of their quite low-grade (>1%) resources. Froth flotation is the most important physicochemical pretreatment technique for processing low-grade sulfide ores. In other words, flotation separation can effectively upgrade finely liberated base metal sulfides based on their surface properties. Various sulfide surface characters can be modified by flotation surfactants (collectors, activators, depressants, pH regulators, frothers, etc.). However, these reagents are mostly toxic. Therefore, using biodegradable flotation reagents would be essential for a green transition of ore treatment plants, while flotation circuits deal with massive volumes of water and materials. Pyrite, the most abundant sulfide mineral, is frequently associated with valuable minerals as a troublesome gangue. It causes severe technical and environmental difficulties. Thus, pyrite should be removed early in the beneficiation process to minimize its problematic issues. Recently, conventional inorganic pyrite depressants (such as cyanide, lime, and sulfur-oxy compounds) have been successfully assisted or even replaced with eco-friendly and green reagents (including polysaccharide-based substances and biodegradable acids). Yet, no comprehensive review is specified on the biodegradable acid depression reagents (such as tannic, lactic, humic acids, etc.) for pyrite removal through flotation separation. This study has comprehensively reviewed the previously conducted investigations in this area and provides suggestions for future assessments and developments. This robust review has systematically explored depression performance, various adsorption mechanisms, and aspects of these reagents on pyrite surfaces. Furthermore, factors affecting their efficiency were analyzed, and gaps within each area were highlighted.
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| 19. |
- Asimi Neisiani, A., et al.
(författare)
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Biodegradable hematite depressants for green flotation separation – An overview
- 2023
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 199
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Forskningsöversikt (refereegranskat)abstract
- Due to environmental issues and the restrictions imposed on mineral flotation separation, the use of biodegradable and environmentally friendly reagents has gained widespread international attention. So far, several investigations have been conducted regarding the eco-friendly flotation separation of iron oxide ores for moving toward sustainable development and cleaner production. Yet, no critical review is specified on the green and eco-friendly depression reagents through their reverse flotation beneficiation. Therefore, this study will comprehensively discuss the previously conducted works in this area and provides suggestions for future assessments and developments. This robust study explored various adsorption aspects of natural-based depressants (polysaccharide-, polyphenolic-, and lignosulfonate-based) on iron oxide minerals (mainly hematite) to create a possible universal trend for each biodegradable depressant derivative. The laboratory and industrial experiments indicated that these depressants (except lignosulfonate-based) could selectively depress hematite at alkaline pHs and enhance its reverse flotation separation from their gangue phases (especially silicates as the main gangue phases). Although these eco-friendly depressants showed promising metallurgical results, several gaps still need to be addressed, notably in surface analyses and their adsorption mechanisms.
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| 20. |
- Bazar, July Ann, et al.
(författare)
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Enhancing froth flotation performance of iron oxide apatite ore tailings through synergistic utilization of organosolv lignin particles and tall oil fatty acid-based collector
- 2024
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 216
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Tidskriftsartikel (refereegranskat)abstract
- Beneficiation of the tailings from Iron Oxide Apatite (IOA) ore has become an important topic in the field of mineral processing as phosphate rock is considered as critical raw material by the European Union. Driven by the strong call for sustainability and green technology, this paper introduces the application of novel and bio-based organosolv lignin particles (OLP) as a reagent for apatite flotation. In the artificial mineral mixture flotation tests, OLP addition or replacement to tall oil fatty acid-based collector (TOFA) was shown to improve flotation kinetics and recovery. In this study, it was demonstrated that one of the widely used commercial TOFA collectors could be replaced with OLP by 70 %. The replacement led to an increase in recovery (+2%) and only a minimal decrease in P grade (−0.3 %) for the rougher-cleaner flotation tests in one of the two feed types tested. The influence of OLP and other reagents on apatite floatability has been investigated through Hallimond tube tests and laboratory scale batch flotation tests as well as zeta potential measurements and spectroscopy tests to further understand the possible mechanism and synergism of reagents in the apatite flotation system.
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| 21. |
- Bergamo, Pedro A. de S., et al.
(författare)
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Use of Kirkpatrick evaluation model in simulation-based trainings for the mining industry - A case study for froth flotation
- 2022
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Ingår i: Minerals Engineering. - : Elsevier Ltd. - 0892-6875 .- 1872-9444. ; 188
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Tidskriftsartikel (refereegranskat)abstract
- Trainings play a vital role in the transference of knowledge between skilled and novice operators in the mineral industry. Evaluation is an important part of those trainings, but many trainings rely solely on the trainees’ feedback. This paper presents how technology enhancement can help produce more effective training evaluations to the mineral industry. It describes a case study involving a froth flotation simulator-based training, including details of the simulation, user interface, and the training program. The training was delivered to sixteen mining operators and evaluated by both the traditional method (trainee's feedback) and with the simulation's learning evaluation. The feedback evaluation showed a high level of satisfaction with the learning results, while the learning evaluation showed a very different training outcome, putting established evaluation methods such as Kirckpatrick's “Four levels” into question. Correlations between the learning results and the operators’ personal information such as process work, and academic experience are also presented.
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| 22. |
- Bhadani, Kanishk, 1991, et al.
(författare)
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Application of design of experiments (DoE) in evaluating crushing-screening performance for aggregates production
- 2024
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Ingår i: Minerals Engineering. - 0892-6875. ; 209
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Tidskriftsartikel (refereegranskat)abstract
- The configuration and the interaction between the crushers and screens enable aggregate producers to produce products that are in accordance with the applicable product certification. However, the performance of the system is seldom optimized for the given conditions and market demand. This paper aims to describe the experimental work and the results of quantifying the crusher and screen performance by applying the design of experiments (DoE) in a full-scale tertiary crushing process of an aggregate production plant with both standard belt-cut sampling as well with continuous processes monitoring. The results show the application of a simplified modelling approach using the design of experiments for the evaluation of crusher performance and circuit performance using experimental data. The research output is able to demonstrate that there exists an interaction effect between the crusher closed side setting and eccentric speed that previously has not been identified with traditional methods. The quantification of interaction between crusher and screen individual performance to the process performance has been demonstrated with both belt-cut samples and continuous process monitoring. Using a DoE, digital experiments can be planned for mapping and quantifying the performance of aggregate production.
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| 23. |
- Bhadani, Kanishk, 1991, et al.
(författare)
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Application of Optimization Method for Calibration and Maintenance of Power-Based Belt Scale
- 2021
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Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Process optimization and improvement strategies applied in a crushing plant are coupled with the measurement of such improvements, and one of the indicators for improvements is the mass flow at different parts of the circuit. The estimation of the mass flow using conveyor belt power consumption allows for a cost-effective solution. The principle behind the estimation is that the power draw from a conveyor belt is dependent on the load on the conveyor, conveyor speed, geometrical design, and overall efficiency of the conveyor. Calibration of the power-based belt scale is carried out periodically to ensure the accuracy of the measurement. In practical implementation, certain conveyors are not directly accessible for calibration to the physical measurement as these conveyors have limited access or it is too costly to interrupt the ongoing production process. For addressing this limitation, a better strategy is needed to calibrate the efficiency of the power-based belt scale and maintain the reliability of such a system. This paper presents the application of an optimization method for a data collection system to calibrate and maintain accurate mass flow estimation. This includes calibration of variables such as the efficiency of the power-based belt scale. The optimization method uses an error minimization optimization formulation together with the mass balancing of the crushing plant to determine the efficiency of accessible and non-accessible conveyors. Furthermore, a correlation matrix is developed to monitor and detect deviations in the estimation for the mass flow. The methods are applied and discussed for operational data from a full-scale crushing plant.
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| 24. |
- Bhadani, Kanishk, 1991, et al.
(författare)
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Applied Calibration and Validation Method of Dynamic Process Simulation for Crushing Plants
- 2021
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Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- There is a need within the production industry for digitalization and the development of meaningful functionality for production operation. One such industry is aggregate production, characterized by continuous production operation, where the digital transformation can bring operational adaptability to customer demand. Dynamic process simulations have the ability to capture the change in production performance of aggregate production over time. However, there is a need to develop cost-efficient methodologies to integrate calibrations and validation of models. This paper presents a method of integrating an experimental and data-driven approach for calibration and validation for crushing plant equipment and a process model. The method uses an error minimization optimization formulation to calibrate the equipment models, followed by the validation of the process model. The paper discusses various details such as experimental calibration procedure, applied error functions, optimization problem formulation, and the future development needed to completely realize the procedure for industrial use. The validated simulation model can be used for performing process planning and process optimization activities for the crushing plant's operation.
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| 25. |
- Bhadani, Kanishk, 1991, et al.
(författare)
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Development and implementation of key performance indicators for aggregate production using dynamic simulation
- 2020
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Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 145
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Tidskriftsartikel (refereegranskat)abstract
- Continuous process improvements are needed to maintain and run an industrial operation at a profitable state. An aggregates production plant consists of multiple process operations such as blasting, primary crushing, followed by secondary and tertiary crushing stages with an intermediate screening of products. Each of these processes can be operated with multiple objectives in mind of operators and plant managers. These objectives can be defined by varying terms like generating required throughput of the plant, maintaining equipment’s health, meeting customers’ demands, etc. The use of the term key performance indicators is recurrent in industry to formalise and represent these objectives of operation. Currently, the KPIs defined by the ISO 22400 standards are widespread for continuous improvements in the manufacturing industry and they are viewed as a support tool to measure improvements. The scope of this paper is to calculate relevant KPIs for an aggregates production plant using dynamic simulations. Further, the KPIs are implemented in a three-stage aggregate production plant using both real-time plant data and dynamic process simulation. The KPIs developed are useful for operators and plant managers to make decisions. The results show the relationship and dependencies of various equipment and process KPIs. The dynamic simulation has potential to be used as an exploration tool to identify the opportunities of improvement in aggregates processing using KPIs as a measure. The KPIs presented in the paper are based on ISO 22400 standard and have potential to be extended to similar processing operations such as coarse and fine comminution for minerals processing. Apart from the diagnostics application, the KPIs implemented in the dynamic simulation platform can be used to explore and optimize a crushing plant’s design and operations.
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