Vanadium-bearing minerals

There are over 65 known vanadium-bearing minerals, some of the more important are Hsted in Table 1. Patronite, bravoite, sulvanite, davidite, and roscoehte are classified as primary minerals, whereas all of the others are secondary products which form in the oxidizing zone of the upper Hthosphere. 

Vanadium is widely distributed in the earth s crust having an abundance of 0.02% by weight. It is found combined in various minerals, coal, and petroleum. It is present in phosphate rock, in some iron ores, and in certain cmde oils in the form of organic complexes. An important source of the vanadium-bearing mineral patronite, which was found in coal at Mina Raga, Peru, has been materially depleted [12]. The world leaders in vanadium production are the United States, the former Soviet Union, South Africa, Namibia, Finland, Norway, and Chile [13]. 

The above techniques have a wide array of applications, including those that are both analytical and physicochemical (such as bonding) in nature. Typical examples of research include the surface chemistry of ferrite minerals (38) and the valence states of copper in a wide array of copper (39) minerals. Other areas of bonding that have been studied include the oxidation state of vanadium (40) in vanadium-bearing aegirities (also using x-ray photoelectron spectroscopy) and the. surface features of titanium perovskites (41). ... 

Vanadium is recovered from several sources vanadium minerals, vanadium-bearing phosphates, boder residues, and spent vanadium catalysts. One major vanadium mineral is patronite, a greenish-black, amorphous sulfide ore used extensively for many years to produce vanadium. This mineral, found in Peru, has depleted gradually. The metal also is recovered commercially from carnotite and roscoelite. 

III. In sulphide ores in which the mineral is associated with hydrocarbons. This class includes the patronite deposits of Peru and various vanadium-bearing asphaltites. It is probable that these asphaltites are the residuary seepage of petroleum deposits, and that they have been formed by the action of (a) hydrocarbons and (6) sulphur or hydrogen sulphide on a fairly porous rock which has been impregnated with a vanadium compound. 

A review of the literature shows that there is a vast amount of crystal field spectral data for iron, the major transition metal in silicate and oxide minerals. The focus of this chapter, therefore, is mainly on ferromagnesian silicates. However, there is also a significant amount of information for chromium-, vanadium- and manganese-bearing minerals. The data are more sporadic for other cations. The optical spectra of the transition metal-bearing minerals enable semi-quantitative estimates to be made of the relative CFSE s of Fe2+, Cr3+, Mn3+, V3+, Ti3+, Ni2+ and Co2+ in many mineral structures. Note, however, that Mn2+ and Fe3+ in high-spin states acquire zero CFSE in oxides and silicates. The crystal field spectra of Mn(II) and Fe(III) minerals are described separately later in the chapter ( 5.10.6 and 5.10.7). 

Faye, G. H. Nickel, E. H. (1970b) On the pleochroism of vanadium-bearing zoisite from Tanzania. Canad. Mineral., 10, 812—21. 

Foit, F. F. Rosenberg, P. E. (1979) The structure of vanadium-bearing tourmaline and its implications regarding tourmaline solid solutions. Amer. Mineral., 64, 788-98. 

There are two other aspects that should be mentioned here that may directly affect the choice of the milling process. First, the uranium ore often contains other metals that have commercial value, like vanadium or niobium, for example, and their recovery may influence the process selected for uranium recuperation. Second, uranium itself may be a by-product of other processes like gold extraction, niobium, and tantalum production or phosphoric acid manufacture. Thus, recovery of low levels of uranium from phosphates, columbite, or gold-bearing minerals may not be economical in itself, but extracting uranium as a by-product from the waste streams of these operations could be commercially sensible. 

With a relative abundance in the Earth s crust of 122 mg/kg, chromium is the 21st most abundant element and the 6th most abundant transition metal after iron, titanium, manganese, zirconium, and vanadium it is more abundant than nickel, zinc, and copper. Though native chromium is extremely rare (e.g, Udachnaya Mine in Russia), most common chromium-bearing minerals are the spinel-type mineral chromite [FeCr O, cubic] and, to a lesser... 

Schmetzer, K. (1978) Der Alexandrit-Effekt in Festkorpem. Naturwiss., 65, 592. Schmetzer, K. (1982) Absorption spectroscopy and colour of V3+-bearing natural oxides and silicates - a contribution to die crystal chemistry of vanadium. Neues Jahrb. Mineral. Abh., 144,73-126. 

Natural releases of vanadium to soil result from weathering of rock-bearing vanadium minerals, precipitation of vanadium particulate from the atmosphere, deposition of suspended particulate from water, and plant and animal wastes. The largest amount of vanadium released to soil occurs through the natural weathering of geological formations (Byerrum et al. 1974 Van Zinderen Bakker and Jaworski 1980). 

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