VALORIZATION OF SOLID WASTE NICKELVANADIUM RICH IN NICKEL AND VANADIUM FUEL OIL PRODUCED BY THE COMBUSTION OF FUEL OIL Ibujés Paulina, De la Torre Ernesto and Guevara Alicia National Polytechnic School Extractive Metallurgy Department Quito - Ecuador

The combustion of fuel oil in boilers Fly ash acumulation Slag incrustation Fuel oil

The problem Fly ash Slag

Acid leaching HNO 3, HCl, H 2 SO 4 Acid leaching HNO 3, HCl, H 2 SO 4 Acid leaching H 2 SO 4 Acid leaching H 2 SO 4 Roasting Stabilization Crystallization solution cake Fly ash methodology Characterization 25°C 24h 20 – 40 g/L 250 – 950 °C 0.5 – 2.0 h Atomic Absorption Spectrophotometer A X-ray diffraction (XRD) in a D8 advance equipment Cake33-60 % Cement % Lime10-33 % 75 °C 25°C 24h 20 – 200 g/L

Fly ash characterization by Atomic Absorption Spectrophotometer ElementsConcentration (%) Iron 5.42 Vanadium 5.31 Nickel 1.61 Calcium, sodium, potassium< 1.00 Fixed carbon Moisture 1.24 Volatile matter 0.86

fly ash roasted at °C Mineralogical content by X-ray diffraction (XRD) equipment MineralFormula CoulsoniteFeV 2 O 5 Sodium vanadium oxideNaV 6 O 15 / Na 0,33 V 2 O 5 Nickel vanadium oxideNiV 2 O 6 Calcium vanadium oxideCa 0,17 V 2 O 5 Iron oxideFe 2 O 3 Iron hydroxide oxideFe 1,833 (OH) 0,5 O 2,5 Grupo plagioclasa (albita, andesita, anortita)(Na,Ca)Al(Si,Al)Si 2 O 8 KarelianiteV2O3V2O3 QuartzSiO 2 Magnesiun Aluminium iron oxideMgAl 0,8 Fe 1,2 O 4

Vanadium, nickel and iron recovery from stirred leaching (750rpm) with H 2 SO g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours.

MineralFormula Approximate composition (%) Iron sulfate Fe 2 (SO 4 ) 3 60 Vanadium oxide V2O5V2O5 27 Morenosite NiSO 4.7H 2 O5 Jambornite (Ni,Fe,Ca)(OH) 2 (OH,S,H 2 O)4 Crystallization of the strong solution The strong solution produced from stirred leaching (750rpm) with H 2 SO g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours.

CarbonC90 RhomboclaseHFe(SO 4 ) 2.4H 2 O10 Stabilization of cake The cake produced from stirred leaching (750rpm) with H 2 SO g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours MineralFormula Approximate composition (%) 31% Cement 31% Cement 38% Cake 38% Cake 31% Lime 31% Lime The standard of public sewer system discharge (Ecuador) U.S. EPA 40 CFR standards, EPA 2003

Leaching HNO 3, HCl, H 2 SO 4, HNO 3+ HCl, NH 3, NaOH, NaCl, NH 4 Cl, Na 2 CO 3 Leaching HNO 3, HCl, H 2 SO 4, HNO 3+ HCl, NH 3, NaOH, NaCl, NH 4 Cl, Na 2 CO 3 Leaching H 2 SO 4 Leaching H 2 SO 4 Roasting Leaching H 2 SO 4 + Br / H 2 O 2 Leaching H 2 SO 4 + Br / H 2 O 2 Leaching H 2 O Leaching H 2 O Roasting NaCl, Na 2 CO 3 Roasting NaCl, Na 2 CO 3 Leaching Na 2 CO 3 Leaching Na 2 CO 3 Leaching H 2 SO 4 Leaching H 2 SO 4 Stabilization Crystallization Slag g/L 25-80°C 2 h °C 2 h °C 18-22% NaCl/Na2CO g/L M g/L Atomic Absorption Spectrophotometer A scanning electron microscope (MEB-EDX) A X-ray diffraction (XRD) in a D8 advance equipment Characterization

ElementsConcentration (%) Vanadium Nickel 8.16 Sodium 1.62 Iron 1.60 Fixed carbon Volatile matter 2.50 Moisture 1.01 Slag characterization by Atomic Absorption Spectrophotometer

Increase 200xIncrease 1500x Si Components distribution of the slag section by scanning electron microscope (MEB-EDX)

Slag roasted at 550 and 650 °C Mineralogical content of the slag by X-ray diffraction (XRD) in a D8 advance equipment MineralFormula Calcium vanadium oxideCa 0,17 V 2 O 5 Sodium vanadium oxideNa 0,33 V 2 O 5 / NaV 6 O 15 BannermaniteNa 0,76 V 6 O 15 CristobaliteSiO 2 Grupo plagioclasa (albita, andesita, anortita) (Na,Ca)Al(Si,Al)Si 2 O 8 Nickel vanadium oxideNiV 2 O 6

Recovery of vanadium, nickel and iron in solution by mean slag leaching

Vanadium, nickel and iron recovery in solution by agitated leaching (750 rpm) with H 2 SO g/L, 25% solids at 70°C.

Vanadium, nickel and iron recovery in solution from agitated leaching (750 rpm) of the solid residue (from H 2 SO 4 leaching) with Na 2 CO 3 2 M at 75°C.

Leaching g/L H 2 SO 4 70 °C 25 % solid Vanadium oxy sulphateV 2 O 3 (SO 4 ) 2 51 Nickel hidrate sulphateNiSO 4.6H 2 O 27 MikasaiteFe 2 (SO 4 ) 3 7 Nickel and potasium hidrate sulphateK 2 NiSO 4.6H 2 O 5 Leaching 2 2 M Na 2 CO 3 75 °C 25 % solid TronaNa 3 H(CO 3 ) 2. H 2 O 28 ThermonatritaNa 2 CO 3. H 2 O 24 BarnesitaNaV 6 O VolborthitaCa 3 (V 2 O 7 )(OH) 2 (H 2 O) 15 Calcium magnesium vanadium oxideCaMgV 2 O 7 14 ProcessApproximate composition (%) Crystallization of the strong solutions

Vanadium nickel oxideNi 3 (VO 4 ) 2 56 Calcium aluminum oxideCaAl 2 O 4 15 Aluminum phospateAlPO 4 8 Iron sulphurFe 7 S 8 6 Stabilization of slag cake The cake produced from leaching sequence with H 2 SO 4 and Na 2 CO 3 was constituted by MineralFormula Approximate composition (%) 40% Cement 40% Cement 50% Cake 50% Cake 10% Lime 10% Lime The standard of public sewer system discharge (Ecuador) U.S. EPA 40 CFR standards, EPA 2003

The fly ash has 5.42wt-% iron, 5.31wt-% vanadium and 1.61wt-% nickel, and amorphous material. (NaV 6 O 15, NiV 2 O 6, Na 0.33 V 2 O 5, NiV 2 O 6, Ca 0,17 V 2 O 5, NaV 6 O 15 ) Fly ash was roasted at 350°C for 1.5 hours and agitated leaching with H 2 SO g/L at 25°C, 25wt-% solids for 8 hours at 750 rpm in order to recover 91wt-% vanadium, 73wt-% nickel and 70wt-% iron in solution Conclusions Fly ash

The slag has 28.72wt-% vanadium, 8.16wt-% nickel, 1.62wt-% iron. (Ca 0,17 V 2 O 5, Na 0,33 V 2 O 5, Na 0,76 V 6 O 15, NaV 6 O 15, NiV 2 O 6, SiO 2 ) Slag was leached with H 2 SO g/L at 70°C, 25wt-% solids for 4 hours stirring (750 rpm) followed by another leaching with Na 2 CO 3 2 M, 75°C, 25wt-% solids and 8 hours in order to recover 75wt-% vanadium, 21wt-% nickel and 34wt-% iron The fly ash and slag processing is costly and complex. Their valorization for vanadium and nickel recovery is possible, but must be evaluated with large scale essays ConclusionsSlag