Carnotite containing vanadium

Vanadium is not found in its pure state. Small amounts of vanadium can be found in phosphate rocks and some iron ores. Most of it is recovered from two minerals vanadinite, which is a compound of lead and chlorine plus some vanadium oxide, and carnotite, a mineral containing uranium, potassium, and an oxide of vanadium. Because of its four oxidation states and its ability to act as both a metal and a nonmetal, vanadium is known to chemically combine with over 55 different elements. 

V. In sedimentary rocks. These minerals also contain oxidised vanadium, and consist of vanadates of iron, aluminium, lead, copper, etc. The carnotite deposits of Colorado are of this type. 

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. 

Vanadium is widely, but sparsely, distributed in the earth s crust (Byerrum et al. 1974 Windholz 1983). It may be found at levels as great as 0.07% in the lithosphere and exists in the form of over 50 different mineral ores (Grayson 1983). The principal ores are carnotite, patronite, roscoelite, and vanadinite (Grayson 1983 Byerrum et al. 1974 Weast 1969 Windholz 1983). Vanadium is also found in phosphate rock, some iron ores, and crude petroleum deposits. Flue-gas deposits from oil-fired furnaces have been found to contain up to 50% vanadium pentoxide (Brooks 1986 Grayson 1983 Symanski 1983 Weast 1969). 

Carnotite is a potassium uranyl vanadate for which the formula K20 2U03 V206 8H20 is frequently given. The ore, however, varies materially from this composition. It contains 19 or 20 per cent V206 and is valuable for both vanadium and uranium, as well as radium. It occurs extensively in Paradox Valley, Colorado, and in Utah, South Australia, Portugal, etc. 

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). 

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. 

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