'Periodica Polytechnica Budapest University of Technology and Economics'
Abstract
Extraction of vanadium and molybdenum from alkaline leaching solution of boiler ash was investigated. The ash coming from heavy oil-fired electrical power station was leached with 8 mol dm^-3 sodium hydroxide at 373 K. The leaching solution was cooled to 278 K; an alkali-precipitate was precipitated. The precipitate was dissolved in sulfuric acid and a selective solvent extraction process was applied. First, almost all the molybdenum was extracted with 1.5% (v/v) tri-n-dodecylamine/kerosene, stripped with 0.5 mol dm-3 NaOH and precipitated with CaCl2 as CaMoO4, then acidified with 30% HNO3, the resulting H2MoO4.H2O was calcinated at 723 K for 4 hours to give molybdenum oxide, next the vanadium was extracted from the raffinate coming from the first solvent extraction with 25% (v/v) tri-n-dodecylamine/kerosene at pH 1.8, stripped with 0.5 mol dm-3 NaOH, precipitated with (NH4)_2SO4 at pH between 7.5-8.5 as ammonium metavanadate and calcinated at 773 K for twenty four hours to yield 99.9% vanadium pen
toxide
