Production of Transformed Red Mud and Application in Mining Waste Treatment

Experience in South West EuropeISCOBA 2011, Dr J.(Hans) J.P. Zijlstra

INTRODUCTION

20 Mt alkaline bauxite refining residue

100 Mt acid metal mining residue

Transformation of red mud

Properties of transformed red mud (TRM)

Production of TRM at Eurallumina SpA

Application of TRM in treatment of mining residue

Economics of TRM application

INTRODUCTION

RED MUD TRANSFORMATION

L/kg pH Cl g/kg SO4 g/kg ANC mol/kg

Red mud - 12.9 <0.1 <0.10 4.5Seawater TRM 8.5 9.2 54.9 8.59 4.0Brine TRM 0.1 9.2 12.5 0.17 4.2

2NaOH + MgCl2 → Mg(OH)2 + 2Na+ + 2Cl-

TRM PROPERTIES

Minerals Formula % WeightSodalite Na4Al3Si3O12Cl 15 - 20

Cancrinite (Na,Ca,K)8(Al,Si)12O24(SO4,CO3)3H2O 5 - 8

Hydrotalcite Mg6Al2CO3(OH)16.4H2O 2 - 4

Brucite Mg3(OH)6 0.5 - 2

Aragonite CaCO3 1 - 3

Gibb./Boehm. Al(OH)3 / y-AlOOH 15 - 25

Hematite Fe2O3 30 - 35

TRM PRODUCTION Eurallumina SpA (Italy)

Brine mixing Thickening Centrifuging

Cement mixing Curing Pellet sieving

ViroMineTM

g/L pHCu mg/L

Fe mg/L

Zn mg/L

SO4

mg/LRaw - 2.0 933 14461 1962 65640Treated 44 8.2 <1 7 <1 68913

TRM APPLICATION Baja Acqua Forte (Portugal)

B.A.F

TESTING

MIXING

SPRAYING

TRM APPLICATION Baja Acqua Forte (Portugal)

TRM APPLICATION Baccu Locci (Italy)

GCT APPLICATION Baccu Locci (Italy)

Testing Reactive barrier Reagent mixing

Mix deposition Filtration Reactive barrier

TRM ECONOMICS

Low efficiency - high volume:TRM has only 20% of arsenate adsorption capacity of GFH.GFH = $1500/t then TRM < $300/t with higher disposal costs.

High efficiency – low volume:EK soil treatment 6 times as efficient with TRM around anode.Economic at TRM = $1500/t.

High efficiency – high volume:Mining waste remediation for $100/t with 10 wt% TRM blend.Competitive at TRM = $100/t incl. transport-, excl. disposal costs.

ACKNOWLEDGEMENTS

Thanks for your attention

Digita-IGAC-CNR: Roberto Peretti, Antonio Zucca | Eurallumina: Giorgio Pompei, Alredo Teodosi |Integra: Paolo Busolo, Alessandro Caviezel, Claudio Cossu | Montana: Alberto Angeloni, Nicola Cogoni,Marco Maroni | TerraPlus: João Barros | Virotec: Daniel Drew, Daniel Faux, Doug Gordon, DavidMcConchie, Bill Prast.