• Kinetics and Mechanism of Phase Transformations from Quartz to Cristobalite 

      Kjelstadli, Marthe Erdal (Master thesis, 2016)
      The largely debated silica polymorphism has in this thesis been investigated for the transformation from β-quartz to β-cristobalite. It is done as a step in understanding and improve the furnace operations of the silicon ...
    • Ore melting and reduction in silicomanganese production 

      Ringdalen, Eli; Gaal, S.; Tangstad, Merete; Ostrovski, Oleg (Journal article; Peer reviewed, 2010)
      The charge for silicomangansese production consists of manganese ore (often mixed with ferromanganese slag) dolomite or calcite, quartz, and in some cases, other additions. These materials have different melting properties, ...
    • An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices 

      du Preez, Stephanus P.; van Kaam, Tristan P. M.; Ringdalen, Eli; Tangstad, Merete; Morita, Kazuki; Bessarabov, Dmitri G.; van Zyl, Pieter G.; Beukes, Johan P. (Peer reviewed; Journal article, 2023)
      Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its ...
    • Parameters Affecting Softening and Melting of Quartz 

      Jusnes, Karin Fjeldstad (Master thesis, 2016)
      The aim of this work was to develop and improve a new method for investigating how different parameters affect the softening and melting of quartz. The method should give quantitative results. Quartz is the stable phase ...
    • Phase transformations and thermal degradation in industrial quartz 

      Jusnes, Karin Fjeldstad (Doctoral theses at NTNU;2020:205, Doctoral thesis, 2020)
      Quartz is used as the silicon source for silicon and ferrosilicon production. Together with various carbon materials, the quartz is added to a submerged arc furnace. Energy is supplied through three carbon electrodes, which ...
    • Phase Transformations from Quartz to Cristobalite 

      Jusnes, Karin Fjeldstad; Tangstad, Merete; Ringdalen, Eli (The Minerals, Metals & Materials Series;, Chapter, 2018)
      Two quartz types used in the silicon and ferrosilicon industry were heated to temperatures of 1600 and 1700 °C. The parameters varied were the temperature and the holding time at maximum temperature. The amount of quartz, ...
    • Phase transformations in quartz used in silicon and ferrosilicon 

      Jusnes, Karin Fjeldstad; Tangstad, Merete; Ringdalen, Eli (Peer reviewed; Journal article, 2021)
      Different quartz types are used as raw material for silicon and ferrosilicon production. Upon heating, the quartz will experience phase transformations to other silica polymorphs. In this study the phase transformation ...
    • Pilot Scale Production of Manganese Ferroalloys Using Heat-Treated Mn-Nodules 

      Tangstad, Merete; Ringdalen, Eli; Manilla, Edmundo; Davila, Daniel (Journal article; Peer reviewed, 2017)
      Pilot-scale experiments are one way to investigate the process patterns and the reaction mechanisms of processes and raw materials. To understand a process fully, both theoretical considerations as well as small-scale ...
    • Pretreatment of manganese ores in CO/CO2/H2 atmospheres 

      Schanche, Trygve Lindahl (Doctoral theses at NTNU;2022:401, Doctoral thesis, 2022)
      During industrial production of manganese ferroalloys, the manganese raw materials are prereduced in the low temperature zone of the submerged arc furnace (SAF). The endothermic Boudouard reaction (CO2 + C = 2CO) consumes ...
    • Reduction Mechanisms in Manganese Ore and Deposition of Carbon from Natural Gas 

      Svoen, Stine (Master thesis, 2017)
      This report investigates the deposition of carbon from natural gas onto manganese ore and the effect of reduction of the higher manganese oxides. Manganese ore has been heated in an argon atmosphere, before methane was ...
    • Reduction of SiO2 to SiC using natural gas 

      Ksiazek, Michal Tomasz; Tangstad, Merete; Dalaker, Halvor; Ringdalen, Eli (Journal article; Peer reviewed, 2014)
      This paper presents a preliminary study of SiC production by use of natural gas for reduction of silica. Direct reduction of SiO2 by gas mixtures containing CH4, H2, and Ar was studied at temperatures between 1273 K and ...
    • Reduction Rates of SiMn Slags from Various Raw Materials 

      Kim, Pyunghwa Peace (Doctoral theses at NTNU;2018:260, Doctoral thesis, 2018)
    • Reduction Rates of SiMn Slags from Various Raw Materials 

      Kim, Pyunghwa Peace (Doctoral theses at NTNU;2018:260, Doctoral thesis, 2018)
      The kinetic information in the SiMn (Silicomanganese) process from melting of raw materials to production of metal was investigated in this work. This is of interest for the SiMn production industries where the effect of ...
    • Road-map for gas in the Norwegian metallurgical industry: greater value creation and reduced emissions 

      Dalaker, Halvor; Ringdalen, Eli; Kolbeinsen, Leiv; Mårdalen, Jostein (Research report, 2017)
      In order to increase the use of gas in metal production, we will need to develop new – and to further develop existing – gas-based technologies, which will need to be adopted on an industrial scale. In order to provide a ...
    • Shock Heating Test of Quartz for Si and FeSi Production 

      Jusnes, Karin Fjeldstad; Tangstad, Merete; Ringdalen, Eli (Research report, 2017)
      Six different quartz types used as raw material for Si and FeSi production, were shock heated to 1500 °C in an induction furnace. The amounts of fines produced were measured and compared. The method has been used before ...
    • SiC formation and SiO reactivity of methane at high temperatures 

      Aarnæs, Trygve Storm; Tangstad, Merete; Ringdalen, Eli (Peer reviewed; Journal article, 2021)
      Methane (CH4) is a carbon source currently not in use in the production of silicon. Using a gaseous carbon source instead of conventional solid carbon sources presents an opportunity to rethink silicon production. Preliminary ...
    • SiC production using SiO 2 and Cagglomerates 

      Li, Fei (Doctoral theses at NTNU;2017:180, Doctoral thesis, 2017)
      Due to the possible shortage of high-quality fossil carbon materials and charcoal for the Si industry, this study will focus on the possibility of using natural gas as the substitute of commercially scarce high quality ...
    • Silicon carbide formation from methane and silicon monoxide 

      Aarnæs, Trygve Storm; Ringdalen, Eli; Tangstad, Merete (Peer reviewed; Journal article, 2020)
      Silicon carbide (SiC) formation plays an important role during the production of elemental silicon. SiC forms through a high temperature reaction between silicon monoxide gas (SiO) and carbon. Currently, the carbon sources ...
    • Slag and its effect on Si and FeSi production 

      Folstad, Marit Buhaug (Doctoral theses at NTNU;2023:317, Doctoral thesis, 2023)
      Silicon (Si) is one of the most useful elements on earth and is popular due to its semiconductor characteristics and its abundance in form of quartz (SiO2). Both metallurgical Si and ferrosilicon (FeSi) are produced ...
    • Steam Reforming of Methane on Sponge Iron: Influence of GasComposition on Reaction Rate 

      Ramos Ribeiro, Tiago; Neto, João Batista Ferreira; Poco, Joao G R; Takano, Cyro; Kolbeinsen, Leiv; Ringdalen, Eli (Peer reviewed; Journal article, 2020)
      Direct Reduction processes use gases (CO and H2) for iron reduction and production of sponge iron or direct reduced iron (DRI). The generation of this gas occurs through methane reforming, which can be done in a reformer ...