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Yangjo Kang - One of the best experts on this subject based on the ideXlab platform.
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study on the refining conditions of nickel pig iron for high purity nickel matte production
Social Science Research Network, 2021Co-Authors: Changwoo Seok, Wonyeong Son, Kihwan Lee, Jin Gyun Park, Yangjo KangAbstract:Nickel has been known to be the most important metallic resource, which has been used in various products, such as multi-layer ceramic capacitors, Li-ion batteries, heat-resistance super alloys. Those Ni resources have various types such as metallic nickel, ferronickel alloy, nickel matte, and nickel sulfate depending on the situation. In a production route of high purity nickel matte from ferronickel, which had been implemented many decades ago, a large amount of by-product, as well as relatively high operational cost, have been recently drawing attention. To resolve arisen problems, nickel pig iron can be suggested as a low-cost raw material. The possibility of upgrading nickel pig iron by removal of Fe and enrichment of Ni was investigated by lab-scale oxidation experiments. It was found that major impurities like C and Si should be removed before Fe oxidation initiates. And decarburization and desiliconization of nickel pig iron were enhanced by Oxygen injection, compared with other Blowing manners. The slag conditions for effective Fe oxidation were discussed using thermodynamic calculation and Oxygen Blowing tests. Conclusively, the continuous addition of CaO during Oxygen Blowing enables the formation of liquid slag and further Fe oxidation. In the case of Fe2O3-SiO2 based slag, liquid slag seems to be limited by MgO dissolution from refractory
Jiaqing Zeng - One of the best experts on this subject based on the ideXlab platform.
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effects of calcium ferrite slag on dephosphorization of hot metal during pretreatment in the bof converter
Journal of materials research and technology, 2020Co-Authors: Qixing Yang, Qi Gao, Jiaqing ZengAbstract:Abstract A study was carried out to examine effects of calcium ferrite slag on dephosphorization of hot metal in the steelmaking BOF, with aims to pick up the speed of slag-forming, increase the slag dumping rate. Laboratory tests using a resistance furnace were performed to examine melting characteristics of calcium ferrite pellets, designed with the optimum ratio of iron oxides (total Fe 55%) to CaO of 3:1. The pellets were put in crucibles with furnace temperature held in the range of 1250–1350 °C for 10 min. The results showed that the melting of pellets was nearly completed at 1250°C and main mineral phases, detected by XRD, in the melted samples were CaO•Fe2O3 and 2CaO•Fe2O3. Based on results of the laboratory tests, experiments of full scale were performed using a converter of 120t, charging the hot metal with C 3.46–6.81%, Si 0.1–1.16%, Mn 0.12–0.30%, P 0.10–0.18%, S 0.017–0.13% and temperature of 1234–1430 °C. For the 13 test heats with 6 min of Oxygen Blowing, the rate of dephosphorization and phosphorus distribution ratio reached to 50–60% and 55.9, respectively, when the calcium ferrite pellets were charged. Averaged slag basicity 1.5–2.0, slag melting point 1280–1310℃, slag viscosity 0.5 pa.s were obtained for the BOF heats adding the calcium ferrite pellet, which ensured the slag foaming height controlled at 2.5–3.0 m during the early stages of the blow. Using above smelting process has increased the rate of slag dumping controlled at 50–70% and enhanced the rate of hot metal dephosphorization over 90%.
Changwoo Seok - One of the best experts on this subject based on the ideXlab platform.
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study on the refining conditions of nickel pig iron for high purity nickel matte production
Social Science Research Network, 2021Co-Authors: Changwoo Seok, Wonyeong Son, Kihwan Lee, Jin Gyun Park, Yangjo KangAbstract:Nickel has been known to be the most important metallic resource, which has been used in various products, such as multi-layer ceramic capacitors, Li-ion batteries, heat-resistance super alloys. Those Ni resources have various types such as metallic nickel, ferronickel alloy, nickel matte, and nickel sulfate depending on the situation. In a production route of high purity nickel matte from ferronickel, which had been implemented many decades ago, a large amount of by-product, as well as relatively high operational cost, have been recently drawing attention. To resolve arisen problems, nickel pig iron can be suggested as a low-cost raw material. The possibility of upgrading nickel pig iron by removal of Fe and enrichment of Ni was investigated by lab-scale oxidation experiments. It was found that major impurities like C and Si should be removed before Fe oxidation initiates. And decarburization and desiliconization of nickel pig iron were enhanced by Oxygen injection, compared with other Blowing manners. The slag conditions for effective Fe oxidation were discussed using thermodynamic calculation and Oxygen Blowing tests. Conclusively, the continuous addition of CaO during Oxygen Blowing enables the formation of liquid slag and further Fe oxidation. In the case of Fe2O3-SiO2 based slag, liquid slag seems to be limited by MgO dissolution from refractory
Qixing Yang - One of the best experts on this subject based on the ideXlab platform.
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effects of calcium ferrite slag on dephosphorization of hot metal during pretreatment in the bof converter
Journal of materials research and technology, 2020Co-Authors: Qixing Yang, Qi Gao, Jiaqing ZengAbstract:Abstract A study was carried out to examine effects of calcium ferrite slag on dephosphorization of hot metal in the steelmaking BOF, with aims to pick up the speed of slag-forming, increase the slag dumping rate. Laboratory tests using a resistance furnace were performed to examine melting characteristics of calcium ferrite pellets, designed with the optimum ratio of iron oxides (total Fe 55%) to CaO of 3:1. The pellets were put in crucibles with furnace temperature held in the range of 1250–1350 °C for 10 min. The results showed that the melting of pellets was nearly completed at 1250°C and main mineral phases, detected by XRD, in the melted samples were CaO•Fe2O3 and 2CaO•Fe2O3. Based on results of the laboratory tests, experiments of full scale were performed using a converter of 120t, charging the hot metal with C 3.46–6.81%, Si 0.1–1.16%, Mn 0.12–0.30%, P 0.10–0.18%, S 0.017–0.13% and temperature of 1234–1430 °C. For the 13 test heats with 6 min of Oxygen Blowing, the rate of dephosphorization and phosphorus distribution ratio reached to 50–60% and 55.9, respectively, when the calcium ferrite pellets were charged. Averaged slag basicity 1.5–2.0, slag melting point 1280–1310℃, slag viscosity 0.5 pa.s were obtained for the BOF heats adding the calcium ferrite pellet, which ensured the slag foaming height controlled at 2.5–3.0 m during the early stages of the blow. Using above smelting process has increased the rate of slag dumping controlled at 50–70% and enhanced the rate of hot metal dephosphorization over 90%.
Kärnä A. - One of the best experts on this subject based on the ideXlab platform.
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Modelling of supersonic top lance and the heat-up stage of the CAS-OB process
Oulun yliopisto, 2018Co-Authors: Kärnä A.Abstract:Abstract The CAS-OB (composition adjustment by sealed argon bubbling - Oxygen Blowing) process is used in secondary steelmaking to adjust the composition and temperature of the steel melt. The steel melt can be heated by oxidizing aluminium in process which feeds aluminium particles and Oxygen to the melt surface. Oxygen is in fed by a top lance, which is an important part of many metallurgical processes and is typically used to deliver Oxygen to steel melt surface by supersonic Blowing. Because observing and measuring the metallurgical processes is challenging due to the high temperature, numerical models predicting the processes are especially important. In this thesis, both top lances and the heat-up stage of the CAS-OB process were studied, and numerical models were constructed. CFD (computational fluid dynamics) were used to study top lances. A turbulence model was adjusted for supersonic flows with experimental data from literature. The CAS-OB process model involves chemical reactions and fluid flows. In order to keep the computation times reasonable, a full fluid flow calculation is not included in the model but is calculated in advance. Heat and mass transfer correlations are calculated with CFD, and the results are then used in the process simulation model. Chemical reactions are calculated based on the law of mass action and thermodynamics. The results were validated with industrial measurements. The CAS-OB heat-up stage model can be used in its current state in process development, and in the future for online control of the process. The CFD model for the top lance can be applied to a lance in any other process.Tiivistelmä CAS-OB-prosessia (composition adjustment by sealed argon bubbling - Oxygen Blowing) käytetään teräksen valmistuksessa sulan teräksen koostumuksen ja lämpötilan säätämiseen. Terässulaa voidaan tarvittaessa lämmittää syöttämällä alumiinikappaleita ja happea sulan pinnalle. Hapen syöttö tapahtuu yliäänilanssilla, jota käytetään monissa metallurgisissa prosesseissa, yleensä toimittamaan happea sulan pinnalle yliäänisellä puhalluksella. Metallurgisten prosessien havainnointi ja mittaaminen ovat haastavia korkeiden lämpötilojen vuoksi, joten numeeriset mallit ovat erityisen tärkeitä prosessien ennustamisessa. Tässä työssä on tutkittu yliäänilansseja ja CAS-OB-prosessin lämmitysvaihetta ja luotu niille numeeriset mallit. Yliäänilanssien tutkimiseen käytettiin numeerista virtauslaskentaa (CFD, computational fluid dynamics). Lanssien mallinnusta varten olemassa olevaa turbulenssimallia muokattiin paremmin yliäänivirtausta kuvaavaksi kirjallisuudesta löytyvän mittaustiedon perusteella. CAS-OB-prosessimallissa huomioidaan virtaus ja kemialliset reaktiot. Koska laskenta-ajat haluttiin pitää käytännöllisinä, virtauslaskentaa ei suoriteta mallissa, vaan se tehdään etukäteen. Aineen- ja lämmönsiirtokertoimet lasketaan CFD-laskennalla, ja tuloksia käytetään prosessimallissa. Kemialliset reaktiot lasketaan perustuen massavaikutuksen lakiin ja termodynamiikkaan. CAS-OB-mallin tulokset on validoitu terästehtaalla tehtyjen kokeiden perusteella. Mallia voidaan käyttää nykyisessä muodossaan prosessin kehityksessä ja tulevaisuudessa myös prosessin ohjauksessa. Yliäänilanssin CFD-mallia voidaan soveltaa myös muihin metallurgisiin prosesseihin
