200 likes | 410 Views
National Polytechnic School Extractive Metallurgy Department Quito - Ecuador. Valorization of solid waste rich in nickel and vanadium produced by the combustion of fuel oil. Ibujés Paulina, De la Torre Ernesto and Guevara Alicia. The combustion of fuel oil in boilers. Fuel oil.
E N D
National Polytechnic School Extractive Metallurgy Department Quito - Ecuador Valorization of solid waste rich in nickel and vanadium produced by the combustion of fuel oil Ibujés Paulina, De la Torre Ernesto and Guevara Alicia
The combustion of fuel oil in boilers Fuel oil Slag incrustation Fly ash acumulation
The problem 60 ton/year Fly ash V Cd Fe Ni Slag
Fly ash methodology Acid leaching HNO3, HCl, H2SO4 Crystallization 25°C 24h 20 – 40 g/L 75 °C solution Acid leaching H2SO4 Roasting 250 – 950 °C 0.5 – 2.0 h 25°C 24h 20 – 200 g/L cake Characterization Stabilization Atomic Absorption Spectrophotometer A X-ray diffraction (XRD) in a D8 advance equipment Cake 33-60 % Cement 33-40 % Lime 10-33 %
Fly ash characterizationby Atomic Absorption Spectrophotometer
Mineralogical content by X-ray diffraction (XRD) equipment fly ash roasted at 550 - 950°C
Vanadium, nickel and iron recovery from stirred leaching (750rpm) with H2SO4 200 g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours.
Crystallization of the strong solution The strong solution produced from stirred leaching (750rpm) with H2SO4 200 g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours.
Stabilization of cake The cake produced from stirred leaching (750rpm) with H2SO4 200 g/L and 25% solids on the fly ash burned at 350°C for 1.5 hours • The standard of public sewer system discharge (Ecuador) • U.S. EPA 40 CFR 261.24 standards, EPA 2003 38% Cake 31% Cement 31% Lime
Slag Leaching HNO3, HCl, H2SO4, HNO3+HCl, NH3, NaOH, NaCl, NH4Cl, Na2CO3 LeachingH2SO4 + Br / H2O2 20-300 g/L 25-80°C Roasting Leaching H2SO4 20-100 g/L 2 h 450-550°C Roasting NaCl, Na2CO3 Characterization Leaching H2O Atomic Absorption Spectrophotometer A scanning electron microscope (MEB-EDX) A X-ray diffraction (XRD) in a D8 advance equipment 2 h 450-550°C 18-22% NaCl/Na2CO3 Crystallization 120-200 g/L 0.5-2.5 M Leaching H2SO4 Leaching Na2CO3 Stabilization
Components distribution of the slag sectionby scanning electron microscope (MEB-EDX) Increase 200x Increase 1500x V Ni Si Fe O
Mineralogical content of the slagby X-ray diffraction (XRD) in a D8 advance equipment Slag roasted at 550 and 650 °C
Recovery of vanadium, nickel and ironin solution by mean slag leaching
Vanadium, nickel and iron recovery in solution by agitated leaching (750 rpm) with H2SO4 200 g/L, 25% solids at 70°C.
Vanadium, nickel and iron recovery in solution from agitated leaching (750 rpm) of the solid residue (from H2SO4 leaching) with Na2CO3 2 M at 75°C.
Stabilization of slag cake The cake produced from leaching sequence with H2SO4 and Na2CO3was constituted by • The standard of public sewer system discharge (Ecuador) • U.S. EPA 40 CFR 261.24 standards, EPA 2003 50% Cake 40% Cement 10% Lime
ConclusionsFly ash The fly ashhas 5.42wt-% iron, 5.31wt-% vanadium and 1.61wt-% nickel, and amorphous material. (NaV6O15, NiV2O6, Na0.33V2O5, NiV2O6,Ca0,17V2O5, NaV6O15) Fly ash was roasted at 350°C for 1.5 hours and agitated leaching with H2SO4 200 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
ConclusionsSlag The slag has 28.72wt-% vanadium, 8.16wt-% nickel, 1.62wt-% iron. (Ca0,17V2O5, Na0,33V2O5, Na0,76V6O15, NaV6O15, NiV2O6, SiO2) Slagwas leached with H2SO4 200 g/L at 70°C, 25wt-% solids for 4 hours stirring (750 rpm) followed by another leaching with Na2CO3 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