Magnesite oxidation

Magnesium carbonate (magnesite), oxide, powder, ribbon, sulphate. 

Ferrovanadium can also be prepared by the thermite reaction, in which vanadium and iron oxides are co-reduced by aluminum granules in a magnesite-lined steel vessel or in a water-cooled copper cmcible (11) (see Aluminumand aluminum alloys). The reaction is initiated by a barium peroxide—aluminum ignition charge. This method is also used to prepare vanadium—aluminum master alloys for the titanium industry. 

Magnesium oxide. The natural minerals, i.e., magnesite (MgCO ), brucite [Mg(OH)9], etc., after being crushed to predetermined size, are calcined at temperatures varying from 1055 to 2000 K, depending upon whether a caustic or a dead-burned produc t (periclase) is being... 

Estimatiofi of Niiroo-ot, Second Method.—Another method w hich dispenses with the small furnace and bicarbonate tube may also be used. The long combustion tube is closed at one end and magnesite m small lumps is introduced into the tube and shaken down to the closed end until there is a layer of about 13- 15 cm. (5—6 in.). This is kept in place by a plug of asbestos and the tube is filled s-uccessively with 5 cm. (2 in.) of coarse copper o.xide, then fine copper oxide mixed with the substance, a further layer of coarse copper oxide, and finally the... 

Those minerals whose solubilities are greater than those of most oxides and silicates, but lower than those of soluble salt minerals, are grouped as semisoluble salt minerals (also called salt-type minerals). The list comprising this particular minerals group is calcite, dolomite, magnesite, barite, gypsum, scheelite, carbonate, phosphate, sulfate and some others. These minerals are characterized mainly by their tonic bonding and as has already been pointed out, by their moderate solubility. 

The most likely mineral phases to oxidize under the kinetic testing conditions are the sulfides. Acidity generated from their oxidation is likely to react with calcite and to a lesser extent magnesite. Talc minerals are unlikely to react with leachate. Expected reactions are therefore of the forms ... 

Refractory bricks composed of oxides of magnesium, chromium, aluminum and iron and trace amounts of silica and calcium oxide are used in roofs of open hearths, sidewalls of electric furnaces and vacuum apparatus and copper converters. Such refractories are made in an arc furnace by fusing mixtures of magnesite and chrome ore. 

The following test materials have often been used FCC catalysts, aluminium oxide, silica gel, glass beads, silica or quartz sand, sea sand, coal and coal ash, petroleum coke, metal powders, resin particles, boric acid, and magnesite powder. Mean particle size ranges from 11 /un to 1,041 /rm, and particle density, from 384 kg/m3 to 7,970 kg/m3. According to Geldart s classification (1973), most of these materials belongs to Class A, some to Class B, and a few to Class D or C, as listed in Table II. 

Like calcium, magnesium oxide occurs in minerals such as magnesite (magnesium carbonate), and dolomite (a mixture of calcium and magnesium carbonates). It is the... 

Therefore the formation of magnetite in that way could hardly be of essential importance in the metamorphism of iron-formations, and martitiza-tion is still less hkely. However, in deposits of other genetic types, for instance skam deposits, oxidation of iron silicates to magnetite at the contact with large masses of carbonate rocks (dolomite, magnesite) can be considered an ore-forming process. The last conclusion is still feasible because the carbon dioxide released in the dissociation of carbonates probably had an undisturbed CO O2 ratio. 

The earliest photosynthetic communities may have contributed to oxidation of the early Earth through production of oxidized cmstal minerals without requiring production of O2. Cmstal rocks today are more oxidized than the mantle, with compositions ranging between the QFM and hematite-magnesite /o buffers. This is best explained as an irreversible oxidation of the cmst associated with methanogenesis and hydrogen escape (Catling et al., 2001). It is unlikely that O2 produced by early photosynthesis ever directly entered the atmosphere. 

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