Vanadium recovery from oil fly ash by leaching, precipitation and solvent extraction processes.
In order to reduce the environmental impact due to land disposal of oil fly ash from power plants and to valorize this waste material, the removal of vanadium was investigated using leaching processes (acidic and alkaline treatments), followed by a second step of metal recovery from leachates involving either solvent extraction or selective precipitation. Despite a lower leaching efficiency (compared to sulfuric acid), sodium hydroxide was selected for vanadium leaching since it is more selective for vanadium (versus other transition metals). Precipitation was preferred to solvent extraction for the second step in the treatment since: (a) it is more selective; enabling complete recovery of vanadate from the leachate in the form of pure ammonium vanadate; and (b) stripping of the loaded organic phase (in the solvent extraction process) was not efficient. Precipitation was performed in a two-step procedure: (a) aluminum was first precipitated at pH 8; (b) then ammonium chloride was added at pH 5 to bring about vanadium precipitation.
Navarro
R
R
Universidad de Guanajuato, Instituto de Investigaciones Científicas, Cerro de la Venada s/n, Pueblito de Rocha, C.P. 36040 Guanajuato, Gto, Mexico.
Guzman
J
J
Saucedo
I
I
Revilla
J
J
Guibal
E
E
D000535:Aluminum / Q000302:isolation & purification; D000643:Ammonium Chloride / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D011232:Chemical Precipitation; D060729:Coal Ash; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D052638:Particulate Matter / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D014639:Vanadium / Q000302:isolation & purification*; D018505:Waste Management
D002254:Carbonates; D060729:Coal Ash; D052638:Particulate Matter; D012996:Solutions; D012997:Solvents; D013464:Sulfuric Acids; D014639:Vanadium; D000643:Ammonium Chloride; C005686:sodium carbonate; D012972:Sodium Hydroxide; D002244:Carbon; D000535:Aluminum; C033158:sulfuric acid