Iron tungstate

The Wolframite Group. The wolframite group comprises iron and manganese tungstate minerals of varying composition. The iron tungstate up to a manganese content... 

There are a whole range of lead-containing relaxors based on lead zinc niobate (PZN), lead iron niobate (PFN), lead iron tungstate (PFW), and solid solutions with each other and with BaTiOs (BT), PbTi03 (PT), and SrTiOs (ST). Some of the solid-solution phases are PMN-PT, PMN-PT-PZN, PMN-PZN, PFN-PFW, PFN-PMN, and PFW-PT. 

Lead iron tungstate (PFW) PbFeWO 183 20,000 Multilayered capacitors... 

Iron tungstate FeW04 NaOH, H2SO4 R-765,825 oil acids Alcohols, pine oil Na2Si03, H2SO4... 

PFW. Lead iron tungstate (from the chemical symbols Pb, Fe, W). pH. Symbol for the acidity or alkalinity of a solution it is a number equivalent to the logarithm, to the base 10, of the reciprocal of the concentration of hydrogen ions in an aqueous solution. The point of neutrality is pH7 a solution with a pH below 7 is acid, above 7 is alkaline. The pH of a casting slip is of practical importance in determining its rheological properties. 

The mechanism and rate of hydrogen peroxide decomposition depend on many factors, including temperature, pH, presence or absence of a catalyst (7—10), such as metal ions, oxides, and hydroxides etc. Some common metal ions that actively support homogeneous catalysis of the decomposition include ferrous, ferric, cuprous, cupric, chromate, dichromate, molybdate, tungstate, and vanadate. For combinations, such as iron and... 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

Determination of tungsten as the trioxide (tannic acid-phenazone method) Discussion. Tungstic acid is incompletely precipitated from solutions of tungstates by tannic acid. If, however, phenazone (2,3-dimethyl-l-phenyl-5-pyrazolone) is added to the cold solution after treatment with excess of tannic acid, precipitation is quantitative. This process effects a separation from aluminium, and also from iron, chromium, manganese, zinc, cobalt, and nickel if a double precipitation is used. 

Many heavy metals react with dithiol to give coloured precipitates, e.g. bismuth, iron(III), copper, nickel, cobalt, silver, mercury, lead, cadmium, arsenic, etc. molybdate and tungstate also react. Of the various interfering elements, only arsenic distils over with the tin when a mixture is distilled from a medium of concentrated sulphuric acid and concentrated hydrobromic acid in a current of carbon dioxide. If arsenic is present in quantities larger than that of the tin it should be removed. 

Refer the readings to a calibration curve prepared from a solution containing spectrographically pure iron to which suitable amounts of standard sodium tungstate solution have been added. 

In Raub and Matthias experiment (16)(55), a bluish-black needle of NaxWOs, produced by the electrolysis of a sodium tungstate melt in an iron crucible, exhibited a transition at 0.57 K. It was first... 

FeN2OjC2,Hi , Iron, tricarbonylbis(2-isocy-amo-l,3-dimethylbenzene)-, 26 54 Fe O WCmHw. Tungstate(2-), nona-carbonyliron-... 

F,SCH, Methanesulfonic acid, trifluoro-iridium, manganese and rhenium complexes, 26 114, 115, 120 platinum complex, 26 126 OiFeCgH, Iron, acetyl dicarbonyl (if -cyclopentadienyl)-, 26 239 0,FeN2C2 Hll(, Iron, tricarbonylbis(2-isocy-ano-l,3-dimethylbenzene)-, 26 54 0.iMoNaCHH5-2 C4H ,02, Molybdate 1 -), tricarbonyl(T) -cyclopentadienyl)-sodium, compd. with 1,2-dimethoxy-ethane-(l 2), 26 343 0,NaWC H5-2 C4H ,02, Tungstate(l -), tricarbonyl(ris-cyclopentadienyl)-... 

Yttrotantalite, -which is found at Ytterby and other parts of Sweden, and in Norway. It is richer in tantalum than in niobium, and contains considerable proportions of yttrium, erbium, cerium, and uranium, together with calcium, iron, etc.2 Tungstates and stannates are also present. 

Although flotation was developed as a separation process for mineral processing and applies lo the sulfides of copper, lead, zinc, iron-molybdenum, cobalt, nickel, and arsenic and to nonsullides, such as phosphates, sodium chloride, potassium chloride, iron oxides, limestone, feldspar, fluorite, chromite, tungstates, silica, coal, and rhodochrosilc, flotation also applies to nonmineral separations. Flotation is used in the water disposal field, particularly in connection with petroleum waste water cleanup. 

---