Browsing by Department "Geological Survey of Finland"
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Item Characterization of sedimentary depositional environments for land use and urban planning in Espoo, Finland(Geological Society of Finland, 2021) Saresma, Maarit; Kosonen, Emilia; Ojala, Antti E.K.; Kaskela, Anu; Korkiala-Tanttu, Leena; Geological Survey of Finland; Department of Civil EngineeringThe capital region of Finland is growing rapidly and into areas with challenging construction conditions such as deep fine-grained sediments. In the coastal city of Espoo, present land use is mainly focused in the southern and central parts, which were submerged by the Baltic Sea during the early and mid-Holocene. These areas have experienced saline and brackish water phases during the history of the Baltic Sea Basin. The deposition environments of the presently studied onshore areas are an analogue for the present day offshore Baltic Sea sedimentation settings for fine-grained material. The results from Baltic Sea studies have demonstrated that the seabed topography has a significant role in the deposition of sediments and their properties. In this study, paleotopographic models were created for the ancient Baltic Sea Basin in the Espoo area 1) after deglaciation and 2) during the Litorina transgression and classified into bathymetric (terrain) zones and structures. Topographic classification was combined with the water depth of the Litorina stage, the thickness of fine-grained deposits and wind fetch to establish the overall characteristics of sedimentary environments in the coastal area. Fine-grained sediments can be found mainly in depressions that are classified here as broad, narrow or local. The study found the most challenging environments for construction purposes in sheltered narrow depressions that contain thick layers of fine-grained sediments deposited during the Litorina transgression. These are mainly located in the southern and central parts of Espoo. Minor deep canyons were also found in the northern parts of Espoo. This study provides new prior knowledge for urban planning and construction design in Espoo. The methodology could be applied to other Baltic Sea coastal cities and areas with fine-grained sediments.Item Characterization of sedimentary depositional environments for land use and urban planning in Espoo, Finland(Geological Society of Finland, 2021) Saresma, Maarit; Kosonen, Emilia; Ojala, Antti E.K.; Kaskela, Anu; Korkiala-Tanttu, Leena; School services, ENG; Geological Survey of Finland; Department of Civil Engineering; Department of Civil EngineeringThe capital region of Finland is growing rapidly and into areas with challenging construction conditions such as deep fine-grained sediments. In the coastal city of Espoo, present land use is mainly focused in the southern and central parts, which were submerged by the Baltic Sea during the early and mid-Holocene. These areas have experienced saline and brackish water phases during the history of the Baltic Sea Basin. The deposition environments of the presently studied onshore areas are an analogue for the present day offshore Baltic Sea sedimentation settings for fine-grained material. The results from Baltic Sea studies have demonstrated that the seabed topography has a significant role in the deposition of sediments and their properties. In this study, paleotopographic models were created for the ancient Baltic Sea Basin in the Espoo area 1) after deglaciation and 2) during the Litorina transgression and classified into bathymetric (terrain) zones and structures. Topographic classification was combined with the water depth of the Litorina stage, the thickness of fine-grained deposits and wind fetch to establish the overall characteristics of sedimentary environments in the coastal area. Fine-grained sediments can be found mainly in depressions that are classified here as broad, narrow or local. The study found the most challenging environments for construction purposes in sheltered narrow depressions that contain thick layers of fine-grained sediments deposited during the Litorina transgression. These are mainly located in the southern and central parts of Espoo. Minor deep canyons were also found in the northern parts of Espoo. This study provides new prior knowledge for urban planning and construction design in Espoo. The methodology could be applied to other Baltic Sea coastal cities and areas with fine-grained sediments.Item Control of Platinum Loss in WEEE Smelting(SPRINGER, 2020-07-01) Klemettinen, Lassi; Avarmaa, Katri; O’Brien, Hugh; Jokilaakso, Ari; Taskinen, Pekka; Department of Chemical and Metallurgical Engineering; Geological Survey of FinlandIn spite of significant economic value, the solubilities of the platinum group and precious metals in metallurgical copper smelting slags are not well known. Recent experimental information on iron-free and low-iron silicate melts indicates that the chemical solubility of platinum is very low, < 1 ppmw (part per million weight). In this study, the concentration of platinum in alumina spinel-saturated iron silicate slags in equilibrium with a solid iron-platinum alloy was measured as a function of oxygen partial pressure at 1300°C. The results were converted to unit activity of platinum by the thermodynamic properties of the iron-platinum alloy formed. This allowed the mechanism of dissolution of platinum in the slag and the forms of platinum species in alumina-rich iron silicate slags in copper scrap smelting and refining conditions to be obtained. Our findings explain some inconsistent results in the geochemical literature by proposing an anionic dissolution mechanism at low oxygen partial pressures in iron-containing silicate slags.Item Novel fluxing strategy of copper matte smelting and trace metals in E-Waste recycling(Elsevier Ltd, 2023-01) Chen, Min; Avarmaa, Katri; Taskinen, Pekka; Klemettinen, Lassi; Michallik, Radoslaw; O'Brien, Hugh; Jokilaakso, Ari; Department of Chemical and Metallurgical Engineering; Geological Survey of Finland; Department of Chemical and Metallurgical EngineeringThe distribution behavior of trace metals between copper matte and spinel-saturated iron silicate slags was investigated at 1250 °C and pSO2 of 0.25 atm at low silica concentrations. The experiments were conducted in magnetite (Fe3O4) spinel crucibles in controlled CO-CO2-SO2-Ar gas mixtures using a high-temperature equilibration-quenching technique. The concentrations of trace elements in matte, spinel, and slag were quantified by electron probe X-ray microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. The trace metals (Ag, Ni, Co, and Sn) in all phases and their distribution coefficients were calculated as a function of matte grade. Results show that silver and nickel can be effectively recovered into matte, whereas cobalt and tin are predominantly deported into slag and gas phases, respectively. These results augment the fundamental thermodynamic data of trace metal distributions in copper smelting processes at low-silica fluxing practices.Item On the MILP Modeling of Remote-Controlled Switch and Field Circuit Breaker Malfunctions in Distribution System Switch Placement(IEEE, 2023) Jooshaki, Mohammad; Karimi-Arpanahi, Sahand; Millar, Robert; Lehtonen, Matti; Fotuhi-Firuzabad, Mahmud; Geological Survey of Finland; University of Adelaide; Department of Electrical Engineering and Automation; Sharif University of Technology; Department of Electrical Engineering and AutomationInstalling sectionalizing switches and field circuit breakers (FCBs) is vital for the fast restoration of customer electricity supply in distribution systems. However, the high capital costs of these protection devices, especially remote-controlled switches (RCSs) and FCBs, necessitate finding a trade-off between their costs and financial benefits. In this study, we propose a mixed-integer linear programming (MILP) model for optimizing switch planning in distribution systems. The proposed model determines the optimal allocation of manual switches, RCSs, and FCBs to minimize the costs of switches and the reliability-oriented expenses. While the former includes the costs of installing and operating the switches, the latter consists of the distribution company’s lost revenue due to the undelivered energy and the regulatory incentives (or penalties) associated with service reliability indices. Two penalty-reward mechanisms are used to account for the financial benefits of increasing the service reliabilitythrough reducing the duration and frequency of interruptions. Proposing a novel reliability assessment model, we consider the possibility of malfunctions in both RCSs and FCBs in a highly efficient manner, which is a major contribution of this work. The proposed MILP model is applied to three test networks to validate its applicability and efficacy. The results show the importance of considering the possibility of switch malfunctions in distribution networks.Item Recycling of tellurium via copper smelting processes(SPRINGER, 2020-03) Klemettinen, Lassi; Avarmaa, Katri; Sukhomlinov, Dmitry; O'Brien, Hugh; Taskinen, Pekka; Jokilaakso, Ari; Department of Chemical and Metallurgical Engineering; Metallurgy (MTG); Geological Survey of FinlandThe modern world continuously demands more raw materials for manufacturing all kinds of products. Nowadays, the lifetime of a single product can be very short, as is the case with electronic appliances. Waste electrical and electronic equipment (WEEE) is one of the fastest growing waste categories, and one of the most promising recycling routes for WEEE is to use it as a feed material in pyrometallurgical copper smelting. This article presents new experimental observations regarding the behavior of tellurium in secondary copper smelting process, and compares the results to primary smelting experiments. In secondary smelting conditions, most of tellurium distributed into the copper phase, and the distribution coefficient between copper and slag decreased with increasing oxygen partial pressure. In the primary smelting experiments, most of tellurium was vaporized into flue dusts, and the distribution coefficient between copper matte and slag increased with increasing oxygen pressure, i.e. increasing matte grade.Item Solubility of Chromium in DON Smelting(TAYLOR & FRANCIS, 2022) Avarmaa, Katri; Strengell, Dan; Johto, Hannu; Latostenmaa, Petri; O’Brien, Hugh; Taskinen, Pekka; Department of Chemical and Metallurgical Engineering; Gasum Oy; Boliden Harjavalta Oy; Geological Survey of FinlandChromia-bearing raw materials in nickel and copper matte smelting are difficult to process due to their tendency of forming solid chromite spinel precipitates, leading to formation of mushy slag and buildups in the smelting vessel. The solubility of chromia in smelting slags, and especially in mattes, are not known accurately and new data for iron-silicate slags in equilibrium with low-iron nickel mattes have been measured at 1350–1450°C. Typical copper-bearing nickel mattes with Ni:Cu≈2 (w/w) in the DON (Direct Outotec Nickel) process with 2 to 10 wt% [Fe]matte have been equilibrated in carefully controlled S2-O2-SO2-Ar gas atmosphere experiments with the corresponding silica saturated iron-silicate slags. The phase assays post quenching were measured by electron probe X-ray microanalysis, including the molten slag and matte as well as the solid phase of chromite spinel. Laser ablation ICP mass spectrometry was used to measure the trace elements in the matte. An additional variable in the slag composition was magnesia concentration, varying from zero to 10 wt% (MgO)slag. The solubility of chromium in the slag at 1400°C was ≈0.7 wt% (Cr) and in the nickel matte 30–100 ppm [Cr], depending on the iron concentration of the sulfide matte. The impact of MgO on the chromium concentration in slag was small and within the experimental error of the measurements.Item Solubility of Palladium in Alumina-Iron Silicate Melts(SPRINGER, 2021-06) Avarmaa, Katri; Klemettinen, Lassi; O’Brien, Hugh; Jokilaakso, Ari; Lindberg, Daniel; Taskinen, Pekka; Department of Chemical and Metallurgical Engineering; Geological Survey of FinlandDissolution and solubility of palladium in iron silicate melts saturated with alumina–iron spinel at 1300°C has been measured using an equilibration-drop quenching technique combined with electron probe microanalysis and laser ablation–inductive coupled plasma–mass spectrometry analysis from polished sections. Composition of the resulting Fe-Pd alloy allowed estimation of the activity of palladium at different oxygen partial pressures, and, thus, the solubilities of palladium in the studied slags in conditions typical of copper and nickel smelting as well as slag cleaning at pO2=10-5 to 10-10 atm. The mechanism of palladium dissolution in the studied iron silicate slags was oxidation by formation of the monovalent oxide species PdO0.5 over the entire oxygen activity range of this study. Testing the applicability of the various palladium isotopes for quantitative analyses of Pd in these types of matrices resulted in a good fit of measured concentrations of 104Pd and 105Pd with interference-corrected 106Pd and 108Pd.Item Statistical approach to identify variables predicting sulphide clay occurrence in southern Finland(Springer, 2023-07) Saresma, Maarit; Löfman, Monica; Kosonen, Emilia; Ojala, Antti E. K.; Korkiala-Tanttu, Leena; Geological Survey of Finland; Mineral Based Materials and Mechanics; University of Turku; Department of Civil EngineeringAcid sulphate soil and sulphide-bearing sediments cause various challenges in construction projects and land use planning, as well as harmful environmental effects. Fine-grained sulphide sediments were mainly formed in coastal areas during the Litorina Sea water phase at approximately 7000 BP in the capital region of Finland, but not all these sediments contain sulphide clay. In this study, environmental and material property variables related to the depositional conditions of sulphide clay were selected for statistical analyses to find their association with the occurrence of sulphide. The datasets consisted of sulphide investigations by the City of Espoo, the City of Helsinki, and the Geological Survey of Finland. Statistically significant associations were found in the study area between the occurrence of sulphide and enumerative variables (i.e., sediment organic content, total clay depth, topographic class in the Litorina Sea phase, and water depth) in the Litorina Sea phase. Locations where sulphide clayis especially likely to occur consist of organic-rich (≥ 2%) thick clay (≥ 15 m) deposits in a topographically narrow depression with deep Litorina water (≥ 30 m), or where there is a moderate depth clay (3–5 m) in a local depression with shallow Litorina water (10–20 m). The best individual predictor for sulphide clay occurrence in the study area was found to be the sediment organic content, and, together with sediment water content, these variables very accurately predicted the occurrence of sulphide clay. In addition, clay depth is a very good predictor and, together with the topographic class narrow depression and the Litorina water depth or current elevation, can be used to predict sulphide occurrence.