Reducing Environmental Pollution of Fuel Fly Ash by Extraction and Removal Vanadium Pentoxide

Recovery of vanadium and nickel from heavy oil fly ash (HOFA): a critical review

“…Aer the leaching process, V is precipitated as NH 4 VO 3 from the leaching solution by adding NH 4 ) 2 SO 4 . 49 The precipitated NH<sub4></sub>VO<sub3></sub> is separated by ltration, dried, and calcined to produce vanadium oxide "V 2 O 5 " according to the next precipitation and calcination reaction equations: Precipitation:…”

“…This is attributed to the fact that the increase in the concentration of metallic elements in the ash due to the thermal pretreatment has an inhibitory effect on the growth of fungus. Hakimi et al 49 optimized the precipitation of V as NH 4 VO 3 compound by adding an ammonium compound to the ltrate aer the leaching process. They compared individual use of three ammonium compounds, namely (NH 4 ) 2 SO 4 ammonium persulfate "(NH 4 ) 2 S 2 O 8 ", and ammonium nitrate "NH 4 NO 3 ".…”

“…Hakimi et al 49 established a flowchart for the extraction of V with a high recovery yield through alkaline leaching of V-rich HOFA using NaOH solution at 95 °C for 4 h. After the leaching, the alkaline leachate is neutralized by adding 4.5 M H 2 SO 4 solution. When the pH is adjusted to 8, dissolved Al and Si are deposited leaving V dissolved as sodium vanadate in the filtrate.…”

“…Hakimi et al 49 optimized the precipitation of V as NH 4 VO 3 compound by adding an ammonium compound to the filtrate after the leaching process. They compared individual use of three ammonium compounds, namely (NH 4 ) 2 SO 4 ammonium persulfate “(NH 4 ) 2 S 2 O 8 ”, and ammonium nitrate “NH 4 NO 3 ”.…”

“…4 h at 550 °C 46, 1 h at 450 °C 49. Nickel is recovered from the acidic leachate of HOFA as NiC 2 O 4 by adding NH 4 ) 2 C 2 O 4 35.…”