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

National Polytechnic SchoolExtractive Metallurgy Department

Quito - Ecuador

The combustion of fuel oil in boilers

Fly ash acumulation Slag incrustation

Fuel oil

60 ton/year

CdFe Ni

V

The problem

Fly ash

Slag

Acid leachingHNO3, HCl, H2SO4

Acid leachingH2SO4

Roasting

Stabilization

Crystallization

solution

cake

Fly ash methodology

Characterization

25°C 24h 20 – 40 g/L

250 – 950 °C0.5 – 2.0 h

Atomic Absorption SpectrophotometerA X-ray diffraction (XRD) in a D8 advance equipment Cake 33-60 %

Cement 33-40 %Lime 10-33 %

75 °C

25°C 24h 20 – 200 g/L

Fly ash characterization by Atomic Absorption Spectrophotometer

Elements Concentration (%)

Iron 5.42

Vanadium 5.31

Nickel 1.61

Calcium, sodium, potassium < 1.00

Fixed carbon 85.00

Moisture 1.24

Volatile matter 0.86

fly ash roasted at 550 - 950°CMineralogical content by X-ray diffraction (XRD) equipment

Mineral Formula

Coulsonite FeV2O5

Sodium vanadium oxide NaV6O15 / Na0,33V2O5

Nickel vanadium oxide NiV2O6

Calcium vanadium oxide Ca0,17V2O5

Iron oxide Fe2O3

Iron hydroxide oxide Fe1,833(OH)0,5 O2,5

Grupo plagioclasa (albita, andesita, anortita) (Na,Ca)Al(Si,Al)Si2O8

Karelianite V2O3

Quartz SiO2

Magnesiun Aluminium iron oxide MgAl0,8Fe1,2 O4

0 2 4 6 8 10 12 14 16 18 20 22 240

102030405060708090

100

V Ni FeLeaching time (h)

Met

al re

cove

ry in

sol

ution

(%)

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.

Mineral Formula Approximate composition (%)

Iron sulfate Fe2(SO4)3 60

Vanadium oxide V2O5 27

Morenosite NiSO4.7H2O 5

Jambornite (Ni,Fe,Ca)(OH)2(OH,S,H2O) 4

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.

Carbon C 90

Rhomboclase HFe(SO4)2.4H2O 10

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

Mineral Formula Approximate composition (%)

31%Cement

38%Cake

31%Lime

The standard of public sewer system discharge (Ecuador)

U.S. EPA 40 CFR 261.24 standards, EPA 2003

LeachingHNO3, HCl, H2SO4, HNO3+HCl, NH3,

NaOH, NaCl, NH4Cl, Na2CO3

Leaching H2SO4

Roasting

Leaching H2SO4 + Br / H2O2

Leaching H2ORoasting

NaCl, Na2CO3

Leaching Na2CO3Leaching H2SO4

Stabilization

Crystallization

Slag

20-300 g/L 25-80°C

2 h 450-550°C

2 h 450-550°C 18-22% NaCl/Na2CO3

120-200 g/L 0.5-2.5 M

20-100 g/L

Atomic Absorption Spectrophotometer

A scanning electron microscope (MEB-EDX)

A X-ray diffraction (XRD) in a D8 advance equipment

Characterization

Elements Concentration (%)

Vanadium 28.72

Nickel 8.16

Sodium 1.62

Iron 1.60

Fixed carbon 46.57

Volatile matter 2.50

Moisture 1.01

Slag characterization by Atomic Absorption Spectrophotometer

Increase 200x Increase 1500x

V Ni Si Fe O

Components distribution of the slag sectionby scanning electron microscope (MEB-EDX)

Slag roasted at 550 and 650 °C

Mineralogical content of the slagby X-ray diffraction (XRD) in a D8 advance equipment

Mineral Formula

Calcium vanadium oxide Ca0,17V2O5

Sodium vanadium oxide Na0,33V2O5 / NaV6O15

Bannermanite Na0,76V6O15

Cristobalite SiO2

Grupo plagioclasa (albita, andesita, anortita)

(Na,Ca)Al(Si,Al)Si2O8

Nickel vanadium oxide NiV2O6

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

H2SO4 +

Br

Na2CO3

H2SO4

HCl-HNO3 (3

:1)

H2SO4

H2SO4 +

H2O2 NH3

NaOH

H2O NaC

l

NH4Cl 0

10

20

30

40

50

60

70

80

90

100

V Ni Fe

0 4 8 12 16 20 240

102030405060708090

100

V Ni Fe

Leaching time (h)

Met

al r

ecov

ery

in s

oluti

on (%

)Vanadium, nickel and iron recovery in solution

by agitated leaching (750 rpm) with H2SO4 200 g/L, 25% solids at 70°C.

0 4 8 12 16 20 240

102030405060708090

100

V Ni Fe

Leaching time (h)

Met

al r

ecov

ery

in s

oluti

on (%

)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.

Leaching 1 200 g/L H2SO4

70 °C25 % solid

Vanadium oxy sulphate V2O3(SO4)2 51Nickel hidrate sulphate NiSO4.6H2O 27

Mikasaite Fe2(SO4)3 7

Nickel and potasium hidrate sulphate K2 NiSO4.6H2O 5

Leaching 2 2 M Na2CO3

75 °C25 % solid

Trona Na3H(CO3)2. H2O 28Thermonatrita Na2CO3. H2O 24Barnesita NaV6O16 16Volborthita Ca3(V2O7)(OH)2(H2O) 15

Calcium magnesium vanadium oxide CaMgV2O7

14

Process Approximate composition (%)

Crystallization of the strong solutions

Vanadium nickel oxide Ni3(VO4)2 56

Calcium aluminum oxide CaAl2O4 15

Aluminum phospate AlPO4 8

Iron sulphur Fe7S8 6

Stabilization of slag cake The cake produced from leaching sequence with H2SO4 and Na2CO3 was constituted by

Mineral Formula Approximate composition (%)

40%Cement

50%Cake

10%Lime

The standard of public sewer system discharge (Ecuador)

U.S. EPA 40 CFR 261.24 standards, EPA 2003

The fly ash has 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

Conclusions Fly ash

The slag has 28.72wt-% vanadium, 8.16wt-% nickel, 1.62wt-% iron. (Ca0,17V2O5, Na0,33V2O5, Na0,76V6O15, NaV6O15, NiV2O6, SiO2)

Slag was 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

Conclusions Slag