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Porto Alegre
Brasil
Santiago-
Chile
Beneficiation of pyrite-rich tailings from coal
jig processing by aqueous elutriation
Alexandre Hahn Englert
Jorge Rubio
Federal University
at Rio Grande Do Sul
www.ufrgs.br/ltm
Laboratório de Tecnologia
Mineral e Ambiental
Research lines:
• Fine mineral processing: High
intensity condition, oil extender
flotation, CRF, multibubbles flotation
• Effluent treatment and water reuse;
removal of ions, oils and colloidal
contaminants
• ~ 50-60% (ROM)
discarded
• Tailings deposits:
presence of pyrite
(FeS2)
AMD
Introduction
Brazilian coal processing
Beneficiation of tailings: main tasks
Tailings Pyrite
Inerts
Coal
Energy
Construction materials
Raw material for
chemical production of:
• S
• H2SO4
• FeSO4
• Fe2(SO4)3
• Beneficiation of a pyrite-rich coal
jigging tailings (50-65%) by aqueous
elutriation (expanded bed)
• Obtain a concentrate with high FeS2
grade: >90 %
Aims
Strategy:
Elutriation
rpyrite >rcoal-Oxi-minerals
water
concentrate
coal
Oxi-minerals
pyrite
• Pyrite-rich tailings from a Coal jigging
stage – R1 (South Brazil)
Experimental
• Comminution + sieving: 100% < 100 mm
• Homogenisation/quartering
• Characterisation: Size, S, Ash content
• Isopropyl xanthate 0 or 50
g/ton (pH 9.5)
• Superficial velocity: 1.2 –
3.6 cm/s
Elutriation
Column I
dint = 2.1 cm l = 28 cm
Column II
dint = 4.8 cm
l = 88 cm
[xanthate]: 0 g/ton
• Superficial velocity:
• 1.1 – 3.8 cm/s
Pulp (pyrite-rich tailings)
Concentrate (elutriation)
Characterisation
0
20
40
60
80
100
0 1 10 100
Volu
me u
nders
ize (%
)
Diameter (mm)
dm = 31 mm
Results
Ash: 65%
Total S: 35-37%
(65-68% FeS2)
30
35
40
45
50
55
60
1.2 2.4 3.6
Tota
l sulp
hur
(%)
Elutriation (superficial) velocity (cm/s)
0 g/ton
50 g/ton (pH 9.5)
Feed sample
70
80
90
100
1.2 2.4 3.6
FeS
2gra
de (%
)
Elutriation (superficial) velocity (cm/s)
0 g/ton
50 g/ton (pH 9.5)
Feed sample
30
40
50
60
70
1.2 2.4 3.6
FeS
2re
covery
(%)
Elutriation (superficial) velocity (cm/s)
0 g/ton
50 g/ton (pH 9.5)
Elutriation (Column II)
70
80
90
100
30
40
50
60
0 1 2 3 4
FeS
2G
rade (%
)
Tota
l m
ass
Recovery
(%)
Elutriation (superficial) velocity (cm/s)
30
40
50
60
70
0 1 2 3 4
FeS
2R
ecovery
(%)
Elutriation (superficial) velocity (cm/s)
Pyrite concentrate
Tailings
All the objectives were met:
1. A rich elutriation concentrate (48-52 % Sulphur or
90-98 % pyrite), at 60-65 % recovery and > 3 cm/s of
superficial velocity
2. The concentrate is being used as a raw material for
ferric-sulphur bearing salts production (lab/pilot
plant)
Conclusions
The project continues to improve operating
parameters, increasing process kinetics and recovery
as follows:
1. Optimizing the xanthate concentration, particles
size distribution and pH;
2. Injection of microbubbles and amine – process
named floto-elutriation (with applications in mineral
fines treatment too..)
Future..
• To all Institutions supporting
research in Brazil
• To all Colleagues at LTM (UFRGS)
students, technicians and researchers
Acknowledgements