Glossary

About Vale

Glossary

Check out some technical and specific terms about dams for a better understanding.

A

Areas of Influence

The areas of scope of an enterprise's environmental impacts. They are defined by environmental analysts and are divided in two categories: Direct Influence Area – Is geographically close to the works and the activity itself, as well as mine operations, beneficiation, etc. Indirect Influence Area – Includes a more comprehensive number of people and systems.

ANM (National Mining Agency)

Agency attached to the Ministry of Mines and Energy, which is responsible for the management of mining activities and Brazilian mineral resources.

C

CECOM (Emergency Control and Communications Center)

Vale´s center, installed in Itabira (Minas Gerais), which controls the actuation of the sirens in emergency situations.

D

Dam

Dams are structures designed by engineers to be used as reservoirs for containment and accumulation of liquid substances or the mixture of liquids and solids from the process that improves the physical and chemical qualities of ore.

Dam Level

Indicator for the volume of the material conditioned in the dam and its safety conditions. Currently, there are four:

Level 0

It indicates the normal status.



Level 1

It indicates some instability. The 24-hour reinforced monitoring begins.

Level 2

It indicates everyone shall evacuate the Self-Rescue Zone as soon as the sirens are actuated. This evacuation procedure will be assisted by Vale and the Civil Defense.



Level 3

This level indicates that the people in the Secondary Safety Zone shall be provided with assistance through educational measures and evacuation training. These trainings are scheduled by the Civil Defense and previously communicated to the local population. The sirens are also actuated to certify that there is no one in the Self-Rescue Zone.

Watch the video to understand the definitions of dams.

Watch the video to understand the definitions of dams levels

Dam Safety Index

Factor constantly evaluated through complex calculations to determine the safety of a dam. Recently, the regulatory agencies have made the criteria of this index even more rigid and conservative, in order to increase the safety of workers and inhabitants of the regions with this type of operation.

Decharacterization

Process that is part of the last phase of the decommissioning of a dam. It refers to the treatment of a structure so that it does not present dam characteristics and is reincorporated to the relief and the environment.

Decommissioning

Process of ending the use of a dam permanently. At the end of the process, the structure becomes stable and is reincorporated to the relief and the environment. To learn more about Vale's decommissioning plan, watch the video.


To learn more about Vale's decommissioning plan, watch the video

Displacement Monitoring via Satellite

Orbital Radar systems use surface imaging techniques in which spots of the region under monitoring are lighted by electromagnetic waves and the reflected signal is used to analyze the behavior of geotechnical structures. Satellites generally use two images to measure consecutive phase changes at identical positions and altitudes, but at different periods. When any displacement occurs in the dam, during the collection of the images, it can be observed through the difference between these images. Possible soil movements can be measured with millimetric accuracy. It is currently used in more than 70 structures at Vale.​​

Downstream Tailings Dam and Upstream Tailings Dam

Downstream tailings dam is the conventional construction method. The dam shell is built on compacted soil, regardless of the type of tailings deposited. Raising is built in the direction of the water flow (downstream).

Upstream tailings dam is the type of dam whose body is built according to the use of tailings by means of progressive raisings on the deposited tailing. Raising is built in the opposite direction of the water flow (upstream). The dam requires coarse tailings so that the shell can be built.

Dry Processing

In the dry treatment, no water (from the environment) is required for the processing of extracted ore; thus, there is no need to build tailings dams.

In the last 10 years, Vale invested almost R$66 billion in facilities and development of technologies for the dry iron ore processing production. Today, most of our iron ore production (about 60%) is though dry processing. The company's goal is to reach about 70% in five years.

E

Emergency Action Plan for Mining Dams

The Emergency Action Plan for Mining Dams (PAEBM, Plano de Ação de Emergência de Barragens de Mineração) is a document with guidelines on prevention and actions required in emergency situations. It was developed by Vale and registered in public institutions.

Environmental Constrains

They are instruments of regulation and control present in all phases of the environmental licensing. These are the rules, obligations, and commitments entered into with the environmental licensing authority at the time the environmental licenses are granted.

ETAF (Fluvial Water Treatment Station)

Water treatment station Installed at the confluence of the Ferro-Carvão stream with the Paraopeba River. The objective of this structure, which is being tested, is to reduce the turbidity of the water and return it to the Paraopeba river. The ETAF will be able to treat approximately 2 million liters per hour.

Evacuation Training

Actions organized by Vale with the communities located near the dam region. These activities simulate safety and evacuation procedures in emergency situations. Days and times are previously scheduled and communicated by Vale. The objective is to make the population aware of its role in case of eventual dam breach.

F

Ferteco Mineração

Company acquired by Vale on April 27, 2001, and responsible for the construction of the dam I of Córrego do Feijão mine.

Flooding Area

It is the picture of a region estimating effects after a dam breach. It presents the amount of material contained in the dam through mathematical templates, possible method for draining the material, and extent of the breach. It is calculated considering safety factors so that, in case of a breach, the real flooding area is smaller than the theoretical flooding area.

G

Geophone

Geophones are sensors installed in the structures of the dams to measure the speed of seismic waves (natural or induced). These sensors are installed at the surface of the structures and collect the vibration waves. Based on the wave speed, the micro seismic monitoring keeps up with the response of the dam to seismic events. They are installed at Itabiruçu, dike 3 – Pontal, and Forquilha III dams.

Geotechnics

Geotechnics studies the behavior of soil and rock, mostly related to changes made by men. It is an extremely relevant phase for any construction, and can be performed by geologists or geotechnical engineers.

Geotechnical Monitoring Center

The monitoring center founded in February 2019 to support Vale's geotechnical operations in the Southeast region. It uses data from radars and 24-hour cameras that monitor Vale's geotechnical structures. Using the instruments available, the geotechnical team reads the areas, and the information is all available in the Monitoring Center, along with the information from radars and cameras that allows Vale to monitor and make decisions in a more secure and assertive way.

I

Immediate Response Group

Internal area of Vale created to ensure focus on structuring actions that involve repairing the damages caused as well as socioeconomic and environmental recovery of Brumadinho and affected municipalities. 

Inclinometer

Instrument that measures angular displacements of the geotechnical structure shell, verifying the inclination by means of holes made in the structure. Three instruments have already been installed at Vargem Grande and Doutor dams, and 234 new inclinometers are being acquired to be installed at two dams.

Inactive Dam

The dam that does not receive waste, but keeps the characteristics of dam (deposited material).

This type of dam is different from those that underwent the decommissioning process; that is, whose structure was changed to be reincorporated to the relief and the environment. To understand the difference, watch the video.

Independent Committee for Extraordinary Advisory on Support and Recovery

The Independent Committee for Extraordinary Advisory on Support and Recovery (CIAEAR, Comitê Independente de Assessoramento Extraordinário de Apoio e Reparação), composed only by external members, was created by Vale to recover from the social and environmental impacts caused by the breach of the dam from Córrego de Feijão mine, in Brumadinho (Minas Gerais).

Independent Committee for Extraordinary Advisory on Investigation

The Independent Committee for Extraordinary Advisory on Investigation (CIAEA, Comitê Independente de Assessoramento Extraordinário de Apuração), composed only by external members, was created by Vale to support the Board of Directors during investigation of the causes and possible responsibilities related to the breach of the dam from Córrego de Feijão mine, in Brumadinho (Minas Gerais).

Independent Committee for Extraordinary Advisory on Dam Safety

The Independent Committee for Extraordinary Advisory on Dam Safety (CIAESB, Comitê Independente de Assessoramento Extraordinário de Segurança de Barragens), composed only by external members, was created by Vale to advise the company on issues related to diagnosis of safety conditions, as well as management and mitigation of risks regarding ore tailings dams, and to recommend measures to be taken for improvement of the safety conditions.

Inspection Drones

The drones are used for visual monitoring of conservation conditions of the dams, considering the shell, crest, bottom drain, tailings beach, and extravasation channels, among others. Several photos of the dam parts are collected, during the drone flight, and will be analyzed later by the responsible geotechnician. Fábrica and Gongo Soco mines are monitored by a drone, and another equipment is being acquired for the dam B3/B4.

N

National Policy for Dam Safety

The National Policy for Dam Safety (PNSB, Política Nacional de Segurança de Barragens), established by law No. 12,334/10, is a public policy and a system for integration of the several agencies and different federal entities in order to ensure integrity of the dams, so as to protect the human beings who depend on them or who live in their surroundings as well as the environment.

O

Ore Processing

The recovery process aimed at improving the chemical and physical properties of ore.

P

Piezometer

The vibrating wire piezometer is used to monitor the progress of piezometric pressure – from the liquid compressibility – in more difficult-to-reach areas of the structures to be monitored. It consists of a pressure measuring device – vibrating wire type – and a temperature measuring device. It measures the water level at the point in which is installed. Today, the dams of Minas Gerais and Mato Grosso do Sul count on 126 piezometers (some in phase of installation). In addition, 626 piezometers are under acquisition phase to be installed in 35 new dams.

R

Radar

It is installed in front of the dam shell, and its operating principle is the emission of electromagnetic waves. It is used to analyze the small longitudinal movements (common for all structures) at the front side of the shell. This is possible by creating multiple sectors along the structure (pixels) and analyzing the behavior of each pixel. Radar monitoring has fast response and millimetric accuracy. Today, there are eight devices operating at Forquilha III, Mar Azul, Vargem Grande, Gongo Soco, B6, and MAC B5 dams. Robotic stations complement the radar monitoring.

Raising

The construction method to increase the storage capacity of a tailings dam. Several methods of raising can be used.

S

Secondary Safety Zone

The Secondary Safety Zone (ZSS, Zona de Segurança Secundária) is the region beyond 10km or 30 minutes from the dam breach point. If the dam breaches, there is enough time for the trained people to act for their own rescue and go to the meeting points for assistance. The meeting points are informed during the trainings conducted by the Civil Defense.

Self-Rescue Zone

The Self-Rescue Zone (ZAS, Zona de Autossalvamento) is the region up to 10km or 30 minutes from the dam breach point.
People are responsible for their own rescue. They must get out of the flooding area and go to a safe zone on her own.


To learn more, watch the video.

Slope

Slope is a generic technical term for any sloping surface that delimits a mass of soil, rock or other material (ore, slag, barren, rubbish, etc.). Slopes can be natural, when they are formed by nature without human interference, or artificial, formed by embankments or modified by works.

In the specific case of mines, slope is the hillside that give support to the pit.

Stability Condition Statement

Document that certifies the safety of a dam. Under current legislation, the signers of this document are the engineers who work in specialized companies hired for the consultancy services.

To learn more, watch the video.

T

Tailings

It is the waste from the recovery process aimed at improving the chemical and physical properties of ore. It is composed of iron ore, sand, and water. It is not toxic, corrosive, or flammable.

Tailings Impoundment Membrane

The structure installed in the Paraopeba river acts as a filtering fabric to prevent the dispersion of the solid particles – such as clay, silt, and organic matter – that cause turbidity of the water and change its transparency. For a better understanding, watch the video.

Tailings Plume

Mixture of water and high concentration of suspended solids carried by the watercourse.

Turbidity

It is a physical property of liquids that reduces transparency due to the presence of suspended material that affects the path of light through the fluid.

V

Video monitoring

A method that uses cameras with remote-drive zoom and movement resources for full-time monitoring (24x7). The infrared ray feature also enables the analysis of night images. Images from video monitoring cameras are sent to a hub device and kept recorded for a minimum of 90 days. Currently, there are 86 monitoring devices at Vale's iron ore dams in Brazil. The use of artificial intelligence with the cameras for movement analysis is under development.

Visual Inspections

Inspections in which the technician goes to the area and checks for cracks or any indication that the dam is not under the conditions required to operate.

W

Wet Processing

It aims at improving the chemical and physical properties of run of mine (ROM). The material from the mine goes through this process (which uses water) and generates as waste a material called tailings. This waste is disposed of in dams.