Magnetite oxidation

Mechanistically chromium additions have been shown to significantly enrich (lOX) in the magnetite oxide layer and, it has been suggested that this lowers its solubility. Additions of small amounts of oxygen to the water, increases the metal s potential and promotes the formation of haematite... 

Silicate iron-formations are relatively rarely encountered in pure form impurities of carbonates and magnetite are usual, hematite is rare. All transitions are observed between magnetite-oxide, carbonate, and silicate rocks. 

FeCb (instead of FeS04) also yields magnetite. Oxidation at RT instead of at 90 C gave smaller crystals (ca. 50 nm) which chemical analysis, unit cell size and magnetic hyperfine properties showed to be partially... 

III. Magnetite— 390 °C exotherm, magnetite oxidizes to hematite accompanied by a mass increase 720 °C endotherm, hematite is transformed to y-Fe203. 

IV. Riebeckite—1075 °C endotherm, riebeckite releases constitution water, decomposes and is transformed to magnetite 1300 °C exotherm, magnetite oxidizes to hermatite. 

STUDY ON THE IMPROVEMENTS OF REDUCTION SWELLABILITY AND LOW TEMPERATURE REDUCTION DISINTEGRATION OF VANADIUM-TITANIUM MAGNETITE OXIDIZED PELLETS... 

Magnetic - from a place called Magnesia where magnetic iron oxide (Magnetite) occurred naturally. 

After aluminium, iron is the most abundant metal and the fourth most abundant of all the elements it occurs chiefly as oxides (for example haematite (FCjO,), magnetite (lodestonej (FC3O4) and as iron pyrites FeSj- Free iron is found in meteorites, and it is probable that primitive man used this source of iron for tools and weapons. The extraction of iron began several thousand years ago, and it is still the most important metal in everyday life because of its abundance and cheapness, and its ability to be cast, drawn and forged for a variety of uses. 

The mixed oxide Fc304 (tri-iron tetroxide) is a black solid, which occurs naturally as magnetite it is formed when iron(III) oxide is strongly heated, and its structure is effectively made up of oxide (O ) and iron(II) and iron(III) ions. 

Minerals. Iron-bearing minerals are numerous and are present in most soils and rocks. However only a few minerals are important sources of iron and thus called ores. Table 2 shows the principle iron-bearing minerals. Hematite is the most plentiful iron mineral mined, followed by magnetite, goethite, siderite, ilmenite, and pyrite. Siderite is unimportant in the United States, but is an important source of iron in Europe. Tlmenite is normally mined for titania with iron as a by-product. Pyrite is roasted to recover sulfur in the form of sulfur dioxide, leaving iron oxide as a by-product. 

The reduction of iron ore is accompHshed by a series of reactions that are the same as those occurring in the blast furnace stack. These include reduction by CO, H2, and, in some cases soHd carbon, through successive oxidation states to metallic iron, ie, hematite [1309-37-17, Fe202, is reduced to magnetite [1309-38-2], Fe O, which is in turn reduced to wustite [17125-56-3], FeO, and then to metallic iron, Fe. The typical reactions foUow. 

HTS catalyst consists mainly of magnetite crystals stabilized using chromium oxide. Phosphoms, arsenic, and sulfur are poisons to the catalyst. Low reformer steam to carbon ratios give rise to conditions favoring the formation of iron carbides which catalyze the synthesis of hydrocarbons by the Fisher-Tropsch reaction. Modified iron and iron-free HTS catalysts have been developed to avoid these problems (49,50) and allow operation at steam to carbon ratios as low as 2.7. Kinetic and equiUbrium data for the water gas shift reaction are available in reference 51. 

Ore Processing. Vanadium is recovered domestically as a principal mine product, as a coproduct or by-product from uranium—vanadium ores, and from ferrophosphoms as a by-product in the production of elemental phosphoms. In Canada, it is recovered from cmde-oil residues and in the Repubhc of South Africa as a by-product of titaniferous magnetite. Whatever the source, however, the first stage in ore processing is the production of an oxide concentrate. 

The Phalaborwa complex ia the northeastern Transvaal is a complex volcanic orebody. Different sections are mined to recover magnetite, apatite, a copper concentrate, vermicuhte, and baddeleyite, Hsted in order of aimual quantities mined. The baddeleyite is contained in the foskorite ore zone at a zirconium oxide concentration of 0.2%, and at a lesser concentration in the carbonatite orebody. Although baddeleyite is recovered from the process tailings to meet market demand, the maximum output could be limited by the requirements for the magnetite and apatite. The baddeleyite concentrate contains ca 96% zirconium oxide with a hafnium content of 2% Hf/Zr + Hf. A comminuted, chemically beneficiated concentrate containing ca 99% zirconium oxide is produced also. 

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