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Recent failure at Pau Branco Mine, MG, Brazil

The recent failure at Pau Branco Mine, MG, Brazil is a classic example of cascading events. At this Vallourec Mineração (VMN) iron ore mine the failure of an uphill structure/slope led to overtopping of a downstream retention structure. As a result a flood reached a highway and the environment. Photograph provided by: Adolfo Tribst Corrêa A bit of Pau Branco innovation history Back in 2015 this mine was touted as a technological success when a new filter press module was installed.…

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ORE2 tailings results

We use archival information to formulate the ORE2_Tailings™ quality note and causality analysis. This includes site visits (when possible and if agreed), photographic historic documentation. Of course information will evolve in time, as new data may become available. Thus, one can use ORE2 tailings results to decide which aspects of the life of a considered structure to study. ORE2_Tailings™ results encompass various dam body’s probabilities. They correspond to the FoS yielded by available engineering analyses and the causality analysis. Here…

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ORE2 tailings technical explanations

The first ORE2_Tailings™ deployment for a given client and selected TSF portfolio is an a priori endeavor insofar it delivers estimates that require calibration and adaptation as new data and new events will occur. In particular, this report will require amendments and updates when, for example, new Space Observation (satellite) or other monitoring results, corrective actions reports, changes in service conditions, new incidents reports and inspections may become available. ORE2 tailings technical explanations: Diagnostic poins  ORE2_Tailings™ is a subset of…

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The impact of standard of care on dams survivability

Using ORE2_Tailings we can quantify the impact of standard of care on dams survivability. In this blogpost we take three dams, namely Dam x, Dam y and Dam z. Their design was identical with initial factor of safety of 1.3. In addition, they had similar QA/QC, construction method, same systemic approach, efforts and uncertainties consideration. Various small mishaps hit the dams along their history. Some repairs occurred, under different contracts, different quality control and finally, at different times. It turns…

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SLM and the Probability of failure of a tailings dam

SLM and the probability of failure of a tailings dam goes back 35 years.  A paper entitled “Probability and Risk of Slope Failure” (Silva et al., 2008) proposed using quantification of expert judgement.  That is a subjective/semi-empirical probability evaluation as a practical alternative for determining probability of slope failure. We call this approach SLM, using the initials of the authors. SLM culminates with semi-empirical relationships between Factor of Safety -FoS- and probability of failure -pf-. That relationship allows to estimate…

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Cognitive biases apply to tailings discussions

Cognitive biases apply to tailings discussions more than one could think. Indeed, cognitive biases can cloud debates and oftentimes lead to worrisome “alternative facts” bordering with fake news. Cognitive biases are likely hidden in glossy documents, websites, seemingly authoritative statistical approaches which are then oftentimes referenced by inattentive readers. The final effect is of course to perpetrate the cognitive drifts. Original authors foster the noble cause of reducing the risks posed by the hazardous structures used to contain tailings, i.e.…

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Light on Tailings dams failures

The Church of England Pensions Board and the Council of Ethics of the Swedish National Pension Funds published some recently collected numbers shedding some light on Tailings dams failures.   How many active dams in the world did we assume earlier? In the literature we oftentimes see the number 3500 to characterize the total tailings dam inventory in the world. We used that number in both the following papers: Oboni, C., Oboni F., Factual and Foreseeable Reliability of Tailings Dams and…

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Riskope’s new book Tailings Dam Management for the Twenty-First Century

Riskope’s new book Tailings Dam Management for the Twenty-First Century is in print. This book is based on over thirty years of world-wide consulting experience, relentless methodological research and development, prior books, courses, seminars delivered to corporate key stakeholders, public and governmental agencies, public hearings, expert witnessing in civil and criminal courts, and over fifty technical papers. Its purpose is to identify and describe risk assessment approaches and risk management practices mining must implement to develop a positive path forward. That is…

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