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Cementite
Published in Harshad K. D. H. Bhadeshia, Theory of Transformations in Steels, 2021
Cementite can be synthesised by gas (CH4+H2+Ar ) carburising of iron oxides at about 750∘C. Figure 8.22 shows the thermal stability of such cementite in the form of time-temperature-transformation curves, when the carbide is reheated to a variety of temperatures. The rate at which it decomposes is a lot slower when made using titanomagnetite, attributed to titanium dissolving in cementite and stabilising it [113]. However, phase equilibrium calculations show that there is a negligible solubility of titanium in cementite Longbottom et al. [113]. On the other hand, when pure cementite is in equilibrium with iron containing dissolved titanium, the cementite for some reason becomes stable to the formation of graphite.
Origin of the apatite-ilmenite deposit of Sept-Îles, Québec, Canada
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
Magnetite, ihnenite and apatite represent the principal oxide phases in the ore deposits. Magnetite is a common accessory mineral in igneous and metamorphic rocks and it is the principal host mineral for vanadium in magmatic ores. In the Critical Zone of the Sept-Îles Complex, magnetite consists of complex solid solution (spinel-hercynite) and titanomagnetite hosting a number of exsolution phases such as ulvospinel and ilmenite. Ilmenite occurs as a relatively coarse intergrowth of lamellae, while ulvospinel forms micron-size complex mesh textures. A number of exsolution products formed at high temperature, most commonly ilmenite, but also other spinels can be found in magnetite. In the Critical Zone of the Sept-Îles Complex, ilmenite laths form a trellis texture in the magnetite (Figure 2). Buddington and Lindsley (1964) stated that most of the titanium could have held in magnetite-ulvospinel solid solution at high temperature, and that ilmenite lamellae have probably originated in high-temperature oxidation of the ulvospinel component of titanomagnétite:.
Study on the beneficiation process of a fine ilmenite in YunNan province
Published in Ai Sheng, Energy, Environment and Green Building Materials, 2015
Due to the sample, ore contains more mud and titanium is disseminated in fine ilmenite and titanomagnetite ore. It is hard to get the ore with a low grade of titanium-qualified concentrate by conventional beneficiation methods. So, this study has processed grinding fineness and field intensity of strong magnetic separation experiments, as well as fineness of shaking table experiments. An optimum beneficiation process has been confirmed by a series of probe experiments.
Beneficiation of fluxed titaniferous slag to a marketable titania product using the modified upgraded slag process
Published in Mineral Processing and Extractive Metallurgy, 2021
Xolisa Goso, Jochen Petersen, Merete Tangstad, Jafar Safarian
Titanomagnetite deposits typically offer a unique opportunity for the production of vanadium, steel, and titanium products. Titanomagnetite is the primary source of vanadium throughout the world and a significant source of steel in countries like China and Russia (Fischer 1975; Moskalyk and Alfantazi 2003; Taylor et al. 2006; Roskill 2010). Titanomagnetite is typically processed by smelting in an electric arc or blast furnace in the presence of dolomite–quartz flux and carbonaceous reductant to produce a valuable vanadium-bearing pig iron and a virtually valueless titanium-bearing slag, referred to as titaniferous slag. The pig iron is processed further to produce vanadium and steel products; the slag is generally discarded in waste dumps. Titaniferous by-product slags have been produced in many industrial operations around the world, including by New Zealand Steel (NZS) (from iron sands), in China by Panzhihua Iron and Steel Corporation (Pangang) and Chengde Iron and Steel (CHMP), in Russia by EVRAZ Nizhny Tagil Iron and Steel Works (NTMK), and in South Africa by (now-defunct) EVRAZ Highveld Steel and Vanadium Corporation (EHSV) (Kelly 1993; Nizhny Tagil Iron and Steel Works 2003; Zhang et al. 2007; Roskill 2010; Steinberg et al. 2011). These slags are typically described by the TiO2–SiO2–Al2O3–MgO–CaO system and contain 8–40 mass% TiO2. Table 1 summarises typical chemical compositions of titaniferous slags.
Solid-state reduction of an Indonesian iron sand concentrate using subbituminous coal
Published in Canadian Metallurgical Quarterly, 2021
Zulfiadi Zulhan, I.B.G. Sumbranang Adhiwiguna, Atneral Fuadi, Nuryadi Saleh
When coal was used as the reducing agent and no pre-oxidation was performed on the iron sand concentrate, the XRD pattern of the reduced composite cylindrical briquettes as a function of temperature in the argon atmosphere is shown in Figure 1. From room temperature to 700°C, the minerals in the samples were found to be magnetite (Fe3O4) and titanomagnetite (Fe2.5Ti0.5O4). Titanomagnetite is a mineral within magnetite and an ulvospinel (Fe2TiO4) solid solution. At 800°C, an amount of magnetite and titanomagnetite transformed into wustite (Fe0.97O). Metallic iron (Fe) was observed at 900°C together with wustite, magnetite, and titanomagnetite. At 1000°C, metallic iron was more dominant and magnetite as well as titanomagnetite disappeared and transformed into ulvospinel (Fe2-xFe2xTi1-xO4 or Fe2TiO4 in general for x = 0) and ilmenite (FeTiO3). Metallic iron was more stable at 1100°C. The XRD results indicate that the reaction proceeds from magnetite or titanomagnetite to wustite, metallic iron, ulvospinel, and ilmenite.
The aeromagnetic expression of New Zealand’s Alpine Fault: regional displacement and entrainment of igneous rock
Published in New Zealand Journal of Geology and Geophysics, 2018
Mark S. Rattenbury, Paul Vidanovich
Aeromagnetic surveys involve a fixed-wing aeroplane or helicopter carrying a magnetometer flying parallel lines, typically tens of kilometres long and separated by 100–400 m, to cover an area of tens to thousands of square kilometres. Accurate GPS-controlled positioning is essential, as is height measurement where a constant height above ground, typically 35–100 m, is sought for draped surveys (Isles and Rankin 2013). The magnetometer records variations in the Earth’s magnetic field intensity; these are influenced by varying concentrations of different magnetic minerals in rocks or sediments at and below the ground surface. High to very high magnetic susceptibility rocks typically contain magnetite or titanomagnetite and are commonly igneous. Other magnetic minerals such as pyrrhotite, hematite or ilmenite have lower magnetic susceptibility but in sufficient concentrations will result in magnetic anomalies. Some sedimentary units contain detrital magnetic minerals and can have moderate to high magnetic susceptibilities. Metamorphism of some sedimentary or igneous rocks can result in the growth of magnetic minerals. The further the sensor is from the magnetic source the weaker and broader the recorded signal, but aeromagnetic surveys can record the signal of strongly magnetic rock units that occur many kilometres below the surface.