• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • Tagged with
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Physico-chemical properties of titaniferous iron-making slags under neutral and under reducing conditions

Van Der Colf, Jacobus Cornelius Gideon Kotze. January 1974 (has links)
A tbesis sutmitted to the Faculty of Engineering in fulfilment of the requirements for the degree of Doctor of Philosophy. / Available data on particularly viscosities of titaniferous melts under oxidizing conditions are reviewed, and an attempt is made to explain the high fluidity of such melts. (Abbreviation abstract) / Andrew Chakane 2018
2

The formation of cementite from hematite and titanomagnetite iron ore and its stability

Longbottom, Raymond James, Materials Science & Engineering, Faculty of Science, UNSW January 2005 (has links)
This project examined the reduction and formation of cementite from hematite and titanomagnetite ores and cementite stability. The aim of the project was to develop further understanding of cementite stability under conditions relevant to direct ironmaking and the mechanism of cementite decomposition. The reduction of hematite and ironsand by hydrogen-methane-argon gas mixtures was investigated from 600??C to 1100??C. Iron oxides were reduced by hydrogen to metallic iron, which was carburised by methane to form cementite. The hematite ore was reduced more quickly than the ironsand. Preoxidation of the ironsand accelerated its reduction. Hematite was converted to cementite faster than preoxidised ironsand. The decomposition of cementite formed from hematite was investigated from 500??C to 900??C. This cementite was most stable at temperatures 750-770??C. The decomposition rate increased with decreasing temperature between 750??C and 600??C and with increasing temperature above 770??C. The stability of cementite formed from pre-oxidised titanomagnetite was studied from 300??C to 1100??C. This cementite was most stable in the temperature range 700-900??C. The rate of decomposition of cementite increased with decreasing temperature between 700??C and 400??C and with increasing temperature above 900??C. Cementite formed from ironsand was more stable than cementite formed from hematite
3

The formation of cementite from hematite and titanomagnetite iron ore and its stability

Longbottom, Raymond James, Materials Science & Engineering, Faculty of Science, UNSW January 2005 (has links)
This project examined the reduction and formation of cementite from hematite and titanomagnetite ores and cementite stability. The aim of the project was to develop further understanding of cementite stability under conditions relevant to direct ironmaking and the mechanism of cementite decomposition. The reduction of hematite and ironsand by hydrogen-methane-argon gas mixtures was investigated from 600??C to 1100??C. Iron oxides were reduced by hydrogen to metallic iron, which was carburised by methane to form cementite. The hematite ore was reduced more quickly than the ironsand. Preoxidation of the ironsand accelerated its reduction. Hematite was converted to cementite faster than preoxidised ironsand. The decomposition of cementite formed from hematite was investigated from 500??C to 900??C. This cementite was most stable at temperatures 750-770??C. The decomposition rate increased with decreasing temperature between 750??C and 600??C and with increasing temperature above 770??C. The stability of cementite formed from pre-oxidised titanomagnetite was studied from 300??C to 1100??C. This cementite was most stable in the temperature range 700-900??C. The rate of decomposition of cementite increased with decreasing temperature between 700??C and 400??C and with increasing temperature above 900??C. Cementite formed from ironsand was more stable than cementite formed from hematite
4

A Study on Vanadium Extraction from Fe-V-P Melts Derived from Primary and Secondary Sources

Lindvall, Mikael January 2017 (has links)
Vanadium extraction methods were developed for iron-vanadium-phosphorus (Fe-V-P) melts derived from processing of V-bearing titanomagnetites and steel slags. Studies on phase relationships of V slags were carried out to provide important understanding of the extraction processes. Phase relationship in vanadiferous slag was investigated experimentally at 1573K, 1673K and 1773K, for the compositional range of 0-6mass% Al2O3, 1-5mass% CaO, 10-17mass% SiO2, with MnO and V2O3 fixed at 5.5mass% and 30mass%, balanced with FeO. The slags were found to be solid-liquid mixtures, of liquid, spinel and in some cases free silica. Alumina was identified as the preferred additive to prohibit precipitation of free silica. A method for V extraction to vanadiferous slag was developed based on Fe-V(2mass%)-P(0.1mass%) melts at 1677K using a semi-industrial scale BOF. Oxidation was carried out with an oxygen enriched air jet and iron ore pellets. The complete dissolution of pellets was achieved by deliberately creating good stirring conditions utilising high momentary decarburisation rates. The P distribution to the slag was low when good stirring conditions was obtained. Phase relationship in Al2O3-CaO(25-35mass%)-SiO2-VOx slag was investigated experimentally at an oxygen partial pressure of 9.37•10-11atm and 1873K. The maximum solubility of V-oxide in the slag was 9-10mass% V2O3. Two solid phases were found, a solid solution of Al2O3 in V2O3 (karelianite) and hibonite with fractionation of V into the crystal structure. V extraction experiments to Al2O3-CaO-SiO2 based slags were carried out in 150kg scale by blowing CO2 gas into the metal bath consisting mainly of 1-10mass% V and 1mass% P. At these conditions, oxidation of V was favoured over Fe. Up to 10-13mass% V2O3 could be dissolved in the slag before a viscous slag saturated in V-oxide was observed. The phosphate capacity in the slag was low and as a result this slag could at once be subjected to a final reduction step for production of ferrovanadium with 40-50mass% V. / Metoder för att utvinna vanadin till högvärdiga vanadinslagger från metallsmältor innehållande främst järn (Fe), vanadin (V) och fosfor (P) utvecklades. Metallsmältorna framställs genom att processa primära V råvaror, såsom titanomagnetit, och sekundära råvaror av i huvudsak vanadinrik stålslagg. Fasstudier av högvärdiga vanadinslagger genomfördes som grund för utvecklingsarbetet. Experimentella fasstudier av vanadinspinellslagg med 30vikt% V2O3 och 5.5vikt% MnO genomfördes vid en temperatur av 1573K, 1673K och 1773K. Övriga komponenter i slaggen varierades inom ett intervall av 0-6vikt% Al2O3, 1-5vikt% CaO och 10-17vikt% SiO2, viktad med järnoxid. Samtliga slagger var sammansatt av både flytande- och fastfas. Den fasta fasen utgjordes främst av en vanadin- och järnrik spinellfas och i vissa fall även av fri SiO2. Genom försök i en stålkonverter i semi-industriell skala utvecklades och validerades en metod för vanadinutvinning från råjärnsmältor innehållande 2vikt% V och 0.1vikt% P, vid en temperatur av 1677K. Oxidationen utfördes med syreanrikad luft via en vattenkyld topplans och genom tillsats av hematit pellets. Omsättningen av pellets säkerhetsställdes genom god omrörning som erhölls under korta perioder med höga gasvolymer som en effekt av hög avkolningstakt. Råjärnet efter behandlingen innehöll cirka 3vikt% C och 0.1vikt% V. Producerad vanadinspinellslagg bestod av upp till 30vikt% V2O3. Fosforfördelningen till slaggen var låg under processbetingelser med god omrörning. Experimentella fasstudier av Al2O3-CaO(25-35vikt%)-SiO2-VOx slagg genomfördes vid en temperatur av 1873K och ett syrepartialtryck av 9.37·10-10atm. Den maximala lösligheten av vanadinoxid i slaggen var 9-10vikt% V2O3. Två fasta faser identifierades, V2O3 (Karelianit) med fast löslighet av Al2O3 och Hibonit med vanadinoxid inlöst i kristallstrukturen. Experimentella försök för att utvinna vanadin från en stålsmälta bestående av 1-10vikt% V och 1vikt% P till en slagg med en initial sammansättning av 7-40vikt% Al2O3, 25-35vikt% CaO och 27-64vikt% SiO2 utfördes i en skala av 150kg. Oxidation av vanadin åstadkoms genom att blåsa in CO2 gas i stålsmältan via en spolsten. Under dessa processförhållanden var oxidationen av vanadin gynnsam framför järn och fosfor. Lösligheten av vanadinoxid i slaggen var upp till 10-13vikt% V2O3. Slagg mättad med vanadinoxid var viskös som en konsekvens av utfällning av V2O3 med inlöst Al2O3. Slaggens gynnsamma vanadin och järn- samt vanadin och fosfor förhållande möjliggör att genom slutreduktion producera ferrovanadin med en vanadinhalt av 40-50vikt% och låg fosforhalt. / <p>QC 20170912</p>

Page generated in 0.0528 seconds