Vanadium extractive concentration

Silicon Reduction. The preparation of ferrovanadium by the reduction of vanadium concentrates with ferrosiUcon has been used but not extensively. It involves a two-stage process in which technical-grade vanadium pentoxide, ferrosiUcon, lime, and fluorspar are heated in an electric furnace to reduce the oxide an iron alloy containing ca 30 wt % vanadium but undesirable amounts of siUcon is produced. The siUcon content of the alloy is then decreased by the addition of more V2O5 and lime to effect the extraction of most of the siUcon into the slag phase. An alternative process involves the... 

Vanadium and nickel are poisons to many catalysts and should be reduced to very low levels. Most of the vanadium and nickel compounds are concentrated in the heavy residues. Solvent extraction processes are used to reduce the concentration of heavy metals in petroleum residues. 

V02.V206 also results as deep blue crystals on heating ammonium metavanadate which has previously been fused and cooled. It is stated that the fused substance does not furnish vanadium pentoxide on being decomposed.10 The residue is extracted with concentrated ammonium hydroxide solution and the oxide precipitated by addition of water. 

At very low concentrations of vanadium (less than 2 x 10 5 M) only monomeric metal species are present209 and the extraction process can be expressed as... 

Butler (B39) described the leaching of carnotite ores that contained high-vanadium-low-lime and low-vanadium-asphaltic-type minerals. The high-vanadium-low-lime ore (less than 2%) is roasted with 6-9 wt. % salt at 850°C and is immediately quenched in 3% hot sodium carbonate solution. The calcine is ground to 65 mesh and uranium and vanadium are dissolved by agitation leaching at 92-96°C. 93% of the uranium and 85% of the vanadium are extracted from the ore. The asphaltic tjq>e ore is roasted at 550°C and 80-85% of the uranium and 35-40% of the vanadium are extracted. The leach solution concentration was maintained between 7 and 9% sodium carbonate. The pulp density was between 45 and 50% solids. 

When the sulfur content of the crude oil is low (usually less than one percent by weight), the crude oil is known as a sweet crude, while crude oil with higher concentrations of sulfur is called sour crude. Removal of sulfur and other impurities form part of the treating processes and sulfur itself can form a valuable by-product in a refinery as an input into the chemical industry. Other impurities include nitrogen, oxygen, and salt, as well as small quantities of metals such as vanadium and nickel that are common in certain of the heavier crude oils. As well as extraction processes to purify oil and its products of impurities, specific additives are also used to react with corrosive or odiferous constituents to produce harmless and odorless substances. Such processes are generally termed sweetening processes. 

Apparently, vanadium is present in the (IV) state The first EPR spectrum reported of an extract of the cap of the mushroom showed clearly an EPR signal characteristic of oxo-vanadium(IV) (97). Although the vanadium concentration in some mushrooms is low, it should be noted that they are similar to those reported for a number of seaweeds that may contain vanadium bromoperoxidases (27). 

The organic matter in these tar sands resembles most crude oils in several respects. Metals always are concentrated in asphaltene fractions. Extracts from tar sands which are high in sulfur content usually have ratios of vanadium-to-nickel greater than unity, while those which are low in sulfur tend to have vanadium-to-nickel ratios less than unity. An exception to this generalization is the Edna, California tar sands, which yield extracts that are high in sulfur content but have vanadium-to-nickel ratios of less than unity. 

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