Minerals vanadium

Vanadium is widespread in the earth s crust, twice as abundant as copper and ten times more than lead. Titanium minerals such as ihnenite often have a V-content of 0.1-0.3%. Vanadium is usually obtained as by-product from the extraction of iron from V-containing iron ores, uranium from V-containing carnotite and phosphorus from V-containing phosphate rocks. 

The phosphate rocks of Idaho and Montana contain 0.1-0.5% vanadium pentoxide. 

The vanadium content is extracted as oxide during the manufacture of phosphoric acid and phosphate fertiHzers. Certain dust ores in Arkansas also contain vanadium 

Vanadium is present in some oils, especially those from Venezuela and Mexico. 

The content can be as high as 1.5 g vanadium per kg oil. Residues after combustion of such oils therefore become a vanadium raw material. In the soot the V-content can be up to 6%, in the fly ash 13% and in boiler residues up to 20%. 

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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. 

Vanadium (0.02% of the lithosphere) is very widely distributed—more than 60 vanadium minerals have been described—but there are few workable... 

Derivation (1) Alkali or acid extraction from vanadium minerals. (2) By igniting ammonium metavanadate. (3) From concentrated ferrophosphorus slag by roasting with sodium chloride, leaching with water and purification by solvent extraction followed by precipitation and heating. 

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). 

Vanadium minerals are essentially formed in the course of geological processes. An epigenic formation of specific minerals is, however, conceivable certain bacteria, such as Pseudomonas vanadiumreductans and Shewanella oneidensis (Figure 1.3), can use vanadate(V) as an external electron acceptor, reducing vanadate(V) to vanadium(IV) [and perhaps even further to vanadium(III)], and thus producing sherwoodite-like inorganic... 

Table 1.1 Selection of vanadium minerals with information on the nature of vanadium.

It exists as a sulfide or in the oxidized form. Of the 60 known vanadium minerals, only patronite (V2S5), roscoelite (K(A1, V)2-[AlSi2 Oio]-(OH, F)2), carnotite (KUO2-VO4 1.5 H2O) and vanadinite [Pb5(V04)3Cl] are commercial sources of vanadium. In none of these ores is vanadium present at more than 3% content. 

Vanadium has an abundance in the earth s crust of about 0.2% (Clark, 1975). It is quite eveniy distributed in minerais. A few commerciai deposits contain more than 3% vanadium pentoxide, but normai concentrations are 0.1 - 1% (NAS. 1974). The main sources of vanadium are vanadium suiphide (patronite), carnotite and titanomagnetite ores. Many crude oiis contain considerabie amounts (even about 0.1%) of vanadium, notably those from Venezuela. The ash obtained from burning vanadium-containing oils may have many tens of per cent vanadium. Vanadium can be extracted from fuel ashes. A considerable amount of vanadium production is based on the extraction of converter slag in the steel industry, which can contain 2-10% (Michels, 1973) or even 25% (NAS 1974) vanadium pentoxide. Vanadium is usually manufactured by converting the vanadium minerals to a water- soluble form (Levanto, 1969). 

Throughout the whole period of discovery, the first three decades of the 19 century, vanadium minerals had been found and vanadium compounds been prepared. The metal itself, however, had not been isolated. BerzeHus showed early that it was impossible to prepare vanadium metal by reduction of the oxide with carbon. This gave vanadium carbide. Nor did reduction with metaUic potassium give the pure metal. 

The uranyl vanadates form mineral groups distinct from the phosphates and arsenates because of the markedly different chemistry of the vanadium ion. Like uranium, vanadium shows several valence states in nature, and its detailed mineralogy is very complex. The crystal chemistry of vanadium was reviewed by Evans.In its lower valence states it forms distinct vanadium minerals, but in its higher valence state 5-1- it com-... 

In the crystal chemistry review of the vanadium minerals it was shown that vanadium occurs as different complex units... 

Weeks A. D. and Thompson M. E. Identification and occurrence of uranium and vanadium minerals from the Colorado Plateaus. Bull. U.S. geol. Surv. 1009B, 1954, 13-62. 

Solids materials that are insoluble in hydrocarbon or water can be entrained in the crude. These are called bottom sediments and comprise fine particles of sand, drilling mud, rock such as feldspar and gypsum, metals in the form of minerals or in their free state such as iron, copper, lead, nickel, and vanadium. The latter can come from pipeline erosion, storage tanks, valves and piping systems, etc. whatever comes in contact with the crude oil. 

Vanadium is found in about 65 different minerals among which are carnotite, roscoelite, vanadinite, and patronite, important sources of the metal. Vanadium is also found in phosphate rock and certain iron ores, and is present in some crude oils in the form of organic complexes. It is also found in small percentages in meteorites. 

Under unusual circumstances, toxicity may arise from ingestion of excess amounts of minerals. This is uncommon except in the cases of fluorine, molybdenum, selenium, copper, iron, vanadium, and arsenic. Toxicosis may also result from exposure to industrial compounds containing various chemical forms of some of the minerals. Aspects of toxicity of essential elements have been pubhshed (161). 

The volatile chlorides ate collected and the unreactedsohds and nonvolatile chlorides ate discarded. Titanium tetrachloride is separated from the other chlorides by double distillation (12). Vanadium oxychloride, VOCl, which has a boiling point close to TiCl, is separated by complexing with mineral oil, reducing with H2S to VOCI2, or complexing with copper. The TiCl is finally oxidized at 985°C to Ti02 and the chlorine gas is recycled (8,11) (see also... 

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. 

Fig. 1. Generalized flow sheet of minerals processing to vanadium products (1).

The ore is ordinarily ground to pass through a ca 1.2-mm (14-mesh) screen, mixed with 8—10 wt % NaCl and other reactants that may be needed, and roasted under oxidising conditions in a multiple-hearth furnace or rotary kiln at 800—850°C for 1—2 h. Temperature control is critical because conversion of vanadium to vanadates slows markedly at ca 800°C, and the formation of Hquid phases at ca 850°C interferes with access of air to the mineral particles. During roasting, a reaction of sodium chloride with hydrous siUcates, which often are present in the ore feed, yields HCl gas. This is scmbbed from the roaster off-gas and neutralized for pollution control, or used in acid-leaching processes at the mill site. 

Zn, Ni, Cu, and W, yet is the seventh most abundant element overall because Cr is concentrated in the earth s core and mantle (1,2). It has atomic number 24 and belongs to Group 6 (VIB) of the Periodic Table and is positioned between vanadium and manganese. Other Group 6 members are molybdenum and tungsten. On a toimage basis, chromium ranks fourth among the metals and thirteenth of aU mineral commodities in commercial production. 

The modem process uses a potassium-sulfate-promoted vanadium(V) oxide catalyst on a silica or kie,selguhr support. The SO2 is obtained either by burning pure sulfur or by roasting sulfide minerals (p. 651) notably iron pyrite, or ores of Cu, Ni and Zn during the production of these metals. On a worldwide basis about 65% of the SO2 comes from the burning of sulfur and some 35% by the roasting of sulfide ores but in some countries (e.g, the UK) over 95% conies from the former. 

A. M. del Rio in 1801 claimed to have discovered the previously unknown element 23 in a sample of Mexican lead ore and, because of the red colour of the salts produced by acidification, he called it erythronium. Unfortunately he withdrew his claim when, 4 years later, it was (incorrectly) suggested by the Frenchman, H. V. Collett-Desotils, that the mineral was actually basic lead chromate. In 1830 the element was rediscovered by N. G. Sefstrom in some Swedish iron ore. Because of the richness and variety of colours found in its compounds he called it vanadium after Vanadis, the Scandinavian goddess of beauty. One year later F. Wohler established the identity of vanadium and erythro-nium. The metal itself was isolated in a reasonably pure form in 1867 by H. E. Roscoe who reduced the chloride with hydrogen, and he was... 

The elements of Group 5 are in many ways similar to their predecessors in Group 4. They react with most non-metals, giving products which are frequently interstitial and nonstoichiometric, but they require high temperatures to do so. Their general resistance to corrosion is largely due to the formation of surface films of oxides which are particularly effective in the case of tantalum. Unless heated, tantalum is appreciably attacked only by oleum, hydrofluoric acid or, more particularly, a hydrofluoric/nitric acid mixture. Fused alkalis will also attack it. In addition to these reagents, vanadium and niobium are attacked by other hot concentrated mineral acids but are resistant to fused alkali. 

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