MetaVanadate, ammonium

The red cake can be further purified by dissolving it in an aqueous solution of Na2C02- The iron, aluminum, and silicon impurities precipitate from the solution upon pH adjustment. Ammonium metavanadate then precipitates upon the addition of NH Cl and is calcined to give vanadium pentoxide of greater than 99.8% purity. 

Vanadium raw materials are processed to produce vanadium chemicals, eg, the pentoxide and ammonium metavanadate (AMV) primary compounds, by salt roasting or acid leaching. Interlocking circuits, in which unfinished or scavenged material from one process is diverted to the other, are sometimes used. Such interlocking to enhance vanadium recovery and product grade became more feasible in the late 1950s with the advent of solvent extraction. 

For solvent extraction of pentavalent vanadium as a decavanadate anion, the leach solution is acidified to ca pH 3 by addition of sulfuric acid. Vanadium is extracted in about four countercurrent mixer—settler stages by a 3—5 wt % solution of a tertiary alkyl amine in kerosene. The organic solvent is stripped by a soda-ash or ammonium hydroxide solution, and addition of ammoniacal salts to the rich vanadium strip Hquor yields ammonium metavanadate. A small part of the metavanadate is marketed in that form and some is decomposed at a carefully controlled low temperature to make air-dried or fine granular pentoxide, but most is converted to fused pentoxide by thermal decomposition at ca 450°C, melting at 900°C, then chilling and flaking. 

For direct precipitation of vanadium from the salt-roast leach Hquor, acidulation to ca pH 1 without the addition of ammonia salts yields an impure vanadic acid when ammonium salts are added, ammonium polyvanadate precipitates. The impure vanadic acid ordinarily is redissolved in sodium carbonate solution, and ammonium metavanadate precipitates upon addition of ammonium salts. Fusion of the directly precipitated ammonium salts can yield high purity V20 for the chemical industry. Amine solvent extraction is sometimes used to recover 1—3 g/L of residual V20 from the directly precipitated tail Hquors. 

For vanadium solvent extraction, Hon powder can be added to reduce pentavalent vanadium to quadrivalent and trivalent Hon to divalent at a redox potential of —150 mV. The pH is adjusted to 2 by addition of NH, and an oxyvanadium cation is extracted in four countercurrent stages of mixer—settlers by a diesel oil solution of EHPA. Vanadium is stripped from the organic solvent with a 15 wt % sulfuric acid solution in four countercurrent stages. Addition of NH, steam, and sodium chlorate to the strip Hquor results in the precipitation of vanadium oxides, which are filtered, dried, fused, and flaked (22). Vanadium can also be extracted from oxidized uranium raffinate by solvent extraction with a tertiary amine, and ammonium metavanadate is produced from the soda-ash strip Hquor. Fused and flaked pentoxide is made from the ammonium metavanadate (23). 

Dissolve 0.6 g anunonium monovanadate (ammonium metavanadate) in 22.5 ml water and carefully add 2.5 ml cone, sulfuric acid and 25 ml acetone. 

AMMO 2.5 EC , cypermetlu-in, 13 Ammonia, 13 Ammonium acetate, 13 Ammonium arsenate, 13 Ammonium benzoate, 13 Ammonium bicarbonate, 13 Ammonium bifluoride, 14 Ammonium bisulfite, 14 Ammonium carbamate, 14 Ammonium carbonate, 14 Ammonium chloride, 14 Ammonium chlorplatmate, 14 Ammonium clu omate, 14 Ammonium citrate, 14 Ammonium diclu omate, 14 Ammonium fluoride, 14 Ammonium fomiate, 15 Ammonium hexafluorosilicate, 15 Ammonium hydroxide, 15 Ammonium metavanadate, 15 Ammonium molybdate, 15 Ammonium nitrate, 15 Ammonium oxalate, 15 Ammonium perfluorooctanoate, 15 Ammonium persulfate, 15 Ammonium phosphate, 15 Ammonium picrate, 16 Ammonium salicylate, 16... 

VOx/ZrOz samples were prepared by three methods (i) adsorption from a solution of ammonium metavanadate (AV) at pH values from 1 to 4, adjusted by nitric acid, (ii) dry impregnation with AV solutions and (iii) adsorption from a solution of VO(acetylacetonate)2 in toluene. 

Usually the nitric acid/amine interaction is more dangerous when impurities that can play a catalytic role are present. This goes for metal oxides such as copper oxides, iron (III) oxide and divanadium pentoxide. Salts such as sodium or ammonium metavanadates, iron trichloride, alkaline chromates and dichromates, cyanoferrates and alkaline or nitrosopentacyanoferrates can also act as catalysts. 

Sodium m-nitrobenzenesulphonate has been proposed as an oxidising agent for vat dyes. It is available as a proprietary product and is claimed to react with leuco compounds more quickly than does peroxide. The solubilised vat leuco esters are most commonly hydrolysed and reoxidised to the insoluble parent dye using sodium nitrite and sulphuric acid. Alternative oxidising agents for vat leuco esters include hydrogen peroxide and ammonium metavanadate (NH4VO3), persulphates and nitric acid [218]. 

The effects of various metal oxides and salts which promote ignition of amine-red fuming nitric acid systems were examined. Among soluble catalysts, copperQ oxide, ammonium metavanadate, sodium metavanadate, iron(III) chloride (and potassium hexacyanoferrate(II) with o-toluidine) are most effective. Of the insoluble materials, copper(II) oxide, iron(III) oxide, vanadium(V) oxide, potassium chromate, potassium dichromate, potassium hexacyanoferrate(III) and sodium pentacyanonitrosylferrate(II) were effective. 

Turpentine and fuming nitric acid do not ignite on contact in absence of added catalysts (fuming sulfuric acid, iron(III) chloride, ammonium metavanadate or copper(II) chloride). 

Molybdovanadic Reagent Suspend 4.0 g of finely powdered ammonium molybdate and 0.1 g of finely powdered ammonium metavanadate in 70 ml DW and grind until dissolved. Add 20 ml of HNOs and dilute to 100 ml with DW. 

Vanadium usually is recovered from its ores by one of two processes, (1) leaching raw mineral with hot dilute sulfuric acid, and (2) roasting ore with common salt to convert vanadium into water soluble sodium vanadates. In the sulfuric acid leaching process, vanadium is extracted from acid leach liquors by solvent extraction with an aliphatic amine or an alkyl phosphoric acid in kerosene. The organic solvent extract then is treated with an aqueous solution of ammonia in the presence of ammonium chloride to convert vanadium into ammonium metavanadate. Alternatively, the organic extract is treated with dilute sulfuric acid or an aqueous solution of soda ash under controlled conditions of pH. Vanadium is precipitated from this solution as a red cake of sodium polyvanadate. 

The sodium polyvanadate obtained above by either method is decomposed thermally at 700°C producing a melt of vanadium pentoxide, V2O5. Pentoxide obtained at this stage is in impure form. Purified vanadium pentoxide is obtained by dissolving the red cake in sodium carbonate solution to precipitate ammonium metavanadate. The metavanadate is decomposed at 320 to 430°C to form highly purified vanadium pentoxide. 

Vanadium pentoxide is an intermediate in recovering vanadium from minerals (See Vanadium). Sodium polyvanadate, obtained as a red cake in one of the steps in extracting vanadium from its ores is calcined at 700°C in air to form a melt of vanadium pentoxide. Pentoxide is prepared in purified form by dissolving red cake in sodium carbonate solution followed by addition of an aqueous solution of ammonia and ammonium chloride. Ammonium metavanadate is precipitated which on decomposition at 320 to 430°C forms vanadium pentoxide. 

Catalyst. A pure precipitated Si02 sample (grade Si 4-5P, AKZO product BET S.A., 395 m g" Pore Volume, 1.14 cm -g" ) has been used "as received", while 4% MoOj/SiOj (BET S.A., 187 m g-l) and 5% V205/Si02 (BET S.A., 231 m2.g-i) catalysts have been prepared by incipient wetness impregnation of the "Si4-5P" Si02 with a basic solution (pH=11) of ammonium heptamolybdate and ammonium metavanadate respectively (23). The impregnated samples were dried at 90°C for 24h and then calcined at 6C)0°C for 16h. 

Ammonium metavanadate [7803-55-6] M 117.0, m 200°(dec). Crystd from conductivity water (20ml7g). 

Prepare 10 g. of potassium metavanadate, KVO 3, either by heating a solution of vanadium pentoxide, V2O5, with the necessary amount of a solution of potassium hydroxide or by boiling the necessary amount of ammonium metavanadate (difficultly soluble) with the required quantity of potassium hydroxide. In either case, obtain the white, needle-shaped crystals by evaporation. 

V0.V205 is produced as a dark blue, crystalline powder when either vanadium pentoxide or ammonium metavanadate is heated with excess of powdered arsenic, or when ammonium metavanadate is reduced with sulphur dioxide at a red heat. It dissolves in nitric acid to a blue solution.8... 

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. 

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