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

jrubio@ufrgs.br

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