Ammonium carbonate vanadate

Cone, aqua ammonia in the cold dissolves carbamate from the commercial carbonate, and it converts the hydrocarbonate into normal carbonate-either by removing half its carbonic monohydride, or by combining with it and with water. If the commercial carbonate be digested with a sat. soln. of ammonia in a closed vessel at 20° to 25°, this salt slowly dissolves, and the soln., on cooling, deposits crystals of ammonium carbamate and a little normal carbonate (NH3)3H20(C02)2-j-NH3 =H20+2C02(NH3)2. C. Arnold has tabulated the solubilities of the freshly precipitated carbonates and hydroxides of most of the common metals in sat. soln. of potassium and ammonium carbonates. A. Ditte studied the action of soln. of ammonium carbonate on vanadic oxide. 

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. 

The most general method for the simultaneous analysis of oxyanions by gas chromatography is the formation of trimethylsilyl derivatives. Trimethylsilyl derivatives of silicate, carbonate, oxalate, borate, phosphite, phosphate, orthophosphate, arsenite, arsenate, sulfate and vanadate, usually as their ammonium salts, are readily prepared by reaction with BSTFA-TMCS (99 1). Fluoride can be derivatized in aqueous solution with triethylchlorosilane and the triethylfluorosilane formed extracted into an immiscible organic solvent for analysis by gas chromatography [685). 

The carbonates, sulphates, and borates are decomposed. The sulphides of the alkalies and alkaline earths are decomposed while the sulphides of arsenic, antimony, molybdenum, zinc, cadmium, tin, iron, lead, copper, mercury, and palladium are not attacked. Cobalt sulphate is not attacked, while the sulphates of the alkalies and alkaline earths are attacked and dissolved. Alkali tungstates, ammonium arsenite and arsenate, copper arsenite, ammonium magnesium arsenate, ammonium molybdate and vanadate, potassium cyanide and ferrocyanide are decomposed. Paraffin is not attacked shellac, gum arabic, gum tragacanth, copal, etc., are decomposed. Celluloid is slowly attacked. Silk paper, gun cotton, gelatin, parchment are dissolved. M. Meslans 22 has studied the esterification of alcohol by hydrofluoric acid. 

The nickel and vanadium in the fly ash from the burning of heavy oil can be recovered by chlorination and distillation, with 67% recovery of the nickel and 100% recovery of the vanadium.265 Another method is to leach out the nickel with aqueous ammonium chloride, followed by treatment with hydrogen sulfide to recover nickel sulfide (in 87% yield), which could be refined in the usual way.266 The vanadium was recovered next in 78% yield by solvent extraction with trioctylamine, followed by treatment of the extract with aqueous sodium carbonate to take the vanadium back into water, and finally ammonium chloride to produce ammonium vanadate. 

The first stage of the Stretford process absorbs H2S over sodium carbonate contained in the wash liquor together with sodium ammonium vanadate, anhydrous citric acid and anthraquinone disulfonic acid. The reaction... 

Vanadium ores are heated to high temperatures with sodium chloride in air to obtain water-soluble sodium vanadate, which is then leached with dilute acids so that a vanadium oxide can be obtained. The precipitate is dissolved in a sodium carbonate solution and ammonium chloride is added to precipitate NH4VO3. Intense heating of NH4VO3 causes it to decompose to V2O5, which is the commercial vanadium compound [13]. Vanadium metal can be purified by several methods including iodine refining [13]. 

VC powder is prepared by the reaction of vanadium oxide or ammonium vanadate with carbon at 1500-1700 C in hydrogen followed by a vacuum heat treatment. The reaction of vanadium metal with carbon under vacuum is also used. VC coatings are deposited by CVD, evaporation or sputtering (see Clusters 14 and IS). 

Reaction of vanadium oxide or ammonium vanadate with carbon at 1500-1700°C in hydrogen followed by a vacuum heat-treatment Reaction of vanadium metal Avith carbon under vacuum... 

Reduced chalcogens. An acidified vanadate gives no precipitate with H2S, which reduces it to V. Ammonium sulfide forms a thiovanadate. Treating an ammo-niacal solution of vanadate with H2S gives a violet-red color, a very good test in the absence of Mo. Aqueous VS4 " is deep violet but it decomposes to brown oxygenated species even in basic solution. Acidification then causes incomplete precipitation of V2S5, soluble in alkalis, alkali carbonates, and sulfides. 

Various flux materials have been used for the preparation of europium-activated yttrium vanadate phosphor from vanadium and rare earth oxides. These include sodium nitrate and carbonate, and sodium and ammonium vanadates (Martin and Trond, 1967 Kauders, 1967 Yokota et al., 1970). A precipitation method in which the rare earths are precipitated in nitric acidic solution with NH4VO3 is also used in the preparation of phosphors (Martin and Trond, 1967). The precipitate is afterwards calcined to the flnal composition. 

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