Phosphorous removal from iron

Wesley and Wall (4 ) and Brown and coworkers (18) collected dust samples at five cotton gins with high volume air samplers at three locations in the gin. The dust was removed from the filters in the seime manner as the weave room dusts discussed above. The average ash content was 32.9%. X-ray fluorescence analyses showed that silicon was the most abundant element detected (7.69%), followed by potassium (1.82%), aluminum (1.46%), calcium (1.15%), magnesium (1.05%), phosphorous (0.52%), iron (0.45%), sulphur (0.33%) and chlorine (0.16%). The total dust was separated into a "respirable fraction" (28) by the sonic sifting procedure and analyzed as above. The ash content of the respirable fraction of gin dusts increased to 46.0%. Only the... 

In the reduction stripping process uranium(IV) in the raw wet process acid is oxidized to uranium(Vl) by treatment with sodium chlorate, hydrogen peroxide or air at 60 to 70°C, the uranium(VI) formed being extracted with trioctylphosphine oxide/di-(2-ethylhexyl)phosphate in kerosene and the resulting solution finally reductively stripped repeatedly with aqueous iron(II) solutions. This results in an enrichment by a factor of 40. After oxidation of the stripped solution with sodium chlorate or ambient oxygen and renewed extraction of the uranium(VI) formed with trioctylphosphine oxide/di-(2-ethylhexyl)phosphate, the phosphoric acid is removed from the organic phase by washing. The uranium(Vl) is then stripped with ammonium carbonate and precipitated as the ammonium diuranyl-tricarbonato-complex. This is filtered off, washed and calcined. 

Gold and mercury are removed from aqueous solution by cementation on metallic copper, while antimony is reduced partly to the metal and partly to Sb(III), and thallium(in) is reduced to T1(I). Iron(III) may be masked with phosphoric acid. 

If, however, phosphoric acid is used, the iron(III) ions are rapidly removed from the column, and a sharp separation results. Subsequently, the copper(II) ions can be removed with hydrochloric acid. Clearly the phosphate ions form a much more stable complex with iron(III) ions, which are rendered colourless, than with copper(II). Complex formation is undoubtedly an important factor in other types of chromatography, particularly in inorganic separations on paper, but in no other technique has it been exploited to quite the same extent as in ion-exchange chromatography. 

What was it about the Coke that removed the iron deposits from our sink It was carbonic acid (H2CO3). (Coke contains lots of phosphoric and citric acid too.)... 

For solvent extraction of a tetravalent vanadium oxyvanadium cation, the leach solution is acidified to ca pH 1.6—2.0 by addition of sulfuric acid, and the redox potential is adjusted to —250 mV by heating and reaction with iron powder. Vanadium is extracted from the blue solution in ca six countercurrent mixer—settler stages by a kerosene solution of 5—6 wt % di-2-ethyIhexyl phosphoric acid (EHPA) and 3 wt % tributyl phosphate (TBP). The organic solvent is stripped by a 15 wt % sulfuric acid solution. The rich strip Hquor containing ca 50—65 g V20 /L is oxidized batchwise initially at pH 0.3 by addition of sodium chlorate then it is heated to 70°C and agitated during the addition of NH to raise the pH to 0.6. Vanadium pentoxide of 98—99% grade precipitates, is removed by filtration, and then is fused and flaked. 

Zincex [Zinc extraction] A process for extracting zinc from pyrite cinder leachate, using organic solvents. The chloride leachate is first extracted with a secondary amine, and then with di(2-ethylhexyl)phosphoric acid to remove iron Developed by Tecnicas Reunidas, first commercialized in 1976, and now used in Spain and Portugal. 

The resulting solution will contain saline impurities such as salts of iron and manganese derived from the barium peroxide. These can be removed by the addition of a little phosphoric acid followed by neutralisation with barium hydroxide solution when the metals are precipitated as phosphates. If necessary, further addition of barium hydroxide may be made m order to precipitate the hydrogen peroxide as pure barium peroxide, which on treatment with the correct quantity of dilute sulphuric acid will give a pure solution of hydrogen peroxide. 

Oxysulfides are also rather important. Y2O2S is used as a host material for Ln + ion emitters (e.g. Eu, Tb) in some phosphors, notably those used in TV screens. When mischmetal is used to remove oxygen and sulfur from impure iron and steel, the product is an oxysulfide, which forms an immiscible solid even in contact with molten steel and thus does not contaminate the product. 

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