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Título

IRON ORE TAILINGS CRITICAL STATE PROPERTIES FROM BASIC LABORATORY TESTS FOR STATIC LIQUEFACTION ANALYSIS

Resumo

Over the past eight years, Brazil has witnessed two significant failures in tailings storage facilities (TSF): the rupture of Fundão TSF in Mariana (2015) and TSF I in Brumadinho (2019). After these incidents, new legislative measures were proposed, introducing the concept of "TSF decharacterization". This involves transitioning from an existing upstream-constructed tailings dam to a structure that no longer primarily serves as a tailing containment facility, thereby functionally reintegrating the structure into the environment. Additionally, the failures prompted increased interest in filtered TSFs in Brazil given their lower risk compared to conventional tailings technologies.

As part of the development of decharacterization and filtered stacks projects, comprehensive geotechnical testing campaigns were carried by practitioners, primarily focused on studying the mechanical behavior of tailings using the Critical State Soil Mechanics (CSSM) framework with the Critical State Locus (CSL) representing a practical mean of assessing tailings strength-deformation characteristics. A substantial database of critical state (CS) parameters was developed and published primarily on iron ore tailings, as most TSF decharacterization and filtered stack projects are situated within the Iron Quadrangle (Minas Gerais) in Brazil-one of the world's largest reserves of iron ore.

The unique features of these tailings, marked by high iron (ferrous) content contributing to a high specific gravity (Gs), render conventional geotechnical correlations not applicable without further considerations. This article compiles CS parameters derived from laboratory testing on over 30 iron ore tailings from various sites in Brazil and globally. These parameters are then compared to basic laboratory data, including fines content (Fc), mean particle size (D50), coefficient of uniformity (Cu), plasticity, Gs, etc. The aim is to establish correlations between basic iron ore tailings data and CS parameters, providing a screening approach to determine whether laboratory results fall within expected ranges or if more detailed tests are necessary when analyzing TSFs static liquefaction.

Palavras-chave

Iron ore tailings, CSSM, basic laboratory tests, static liquefaction, decharacterization, filtered stack

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