How the process works

Through new technologies, we prioritize the reuse of material as an alternative in the treatment of waste and tailings.

This proposal is applied at the Morro Agudo Mine, where tailings are a commercially viable byproduct. When this is not applicable, Nexa uses three different forms of disposal, in order of preference: backfill, dry stacking and disposal in dams.

Other operations may have more than one disposal method. At the Atacocha, El Porvenir and Cerro Lindo units, we adopted the backfill system, in which part of the waste is filtered, separating water and solids.

At the Vazante and Aripuanã Mines, we dispose of waste in piles, which reduces environmental impacts and risks to the operation.

Backfill Dry stacking Dam

Backfill refers to filling the mine with tailings, inserted into the voids of underground mines, with the purpose of increasing the structural stability of the mine, providing platforms, improving ore recovery and disposing of tailings.

Underground disposal of tailings in mining pits can occur when the waste is considered inert, excluding the possibility of contaminating water or soil.

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Also called filtered tailings pile/deposit, or dewatered tailings, the Pulp Tailings that leaves the beneficiation goes through processes (combined or single) of filtering, drying, handling, until they obtain moisture levels below 20%.

With the extraction of water from the pulp (mixture of a liquid fluid plus ore or waste), the solid part is stored or formed into piles, ensuring a reduction in environmental impact.

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A dam is a structure built for the purpose of permanent or temporary containment, accumulation or storage of water, liquid substances or mixtures of liquids and solids.

The term dam includes not only the dam, but also all associated structures, such as: overflows and spillways, reservoir, approach channel, diversion structures, return channel, water intakes, and water collection, saddle dyke, among others.

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Status of dams and deposits

The disposal of waste at NEXA offers several alternatives, but all they comply with the best practices and technologies available. You can follow the status of structures (dams, lagoons and reservoirs) at each site and the construction method for each of them.







Brazil Peru


Dams and tailing deposits in Brazil


Morro agudo
Três Marias
Juiz de Fora
01 2 3 4 5 6 7 8 9 10
Active Inactive


Dams and tailing deposits in Peru


Cerro Lindo
El Povenir
01 2 3 4 5 6 7 8 9 10
Active Inactive

Data and documents

Tailings, Waste and Water Management System

To control and monitor dams and tailings deposits, we apply guidelines from the International Commission on Large Dams (ICOLD) and the Canadian Dam Association (CDA).

We adopt processes and procedures that form the Integrated Dams Management System (SIGBar) and an Integrated Deposit Management System (SIGDep). During this process, routine monitoring of structures is carried out and a monthly report is issued which is taken to all hierarchical levels in the company.

Tailings, Waste and Water Management System

What is SIGBAR?                                                                                                                                              What is SIGBAR and SIGDEP? SIGBAR is a dam management system developed by Geoconsultoria, whose objective is to guarantee the stability of dams, and SIGDEP of deposits, so that any potential deficiencies are informed in advance, enabling preventive actions.

Modules                                                                                                                                                                  Each module has the function of standardizing a unique way of acting.

ICOLD – International Commission on Large Dams
CBDB – Brazilian Committee of Large Dam

We have processes and procedures that form the Integrated Dam Management System (SIGBar).

This system is made up of 12 modules that establish rules and measures for regular monitoring actions, from which we control all structures. SIGBar establishes guidelines for document management, monitoring, evaluation, risk analysis, compliance with standards and legislation, staff training, operation of structures and other provisions.

This work is permanently monitored by an independent company, which receives data from biweekly inspections and consolidates data from all monitoring monthly to issue stability reports.


Modules implemented in 2007


Definition of preliminary planning activities


Geotechnical monitoring activities and record


Assessment and recording of behavior and safety


Organization, registration and availability of documents


Analysis of legislation and verification of applicable Requirements


Provision of key information about dams


Training of everyone involved in management


Dam operation manual and operational controls


Risk analysis identifying the risk condition of the structure


PAE including the “dam break” or ZAS - Auto Rescue Zone

Modules implemented in 2007


Monitors the useful life of each structure


Environmental function monitoring

Dam management routine
  • Comply with operational procedures
  • Conduct operational inspections
  • Perform monitoring
Every 15 days
  • Conduct on-site inspections of safety conditions
  • Perform monitoring
  • Sending data to external company for evaluation.
  • Sending data to external company for stability assessment
  • Perform monitoring
  • Issue the SIGBAR indicator
  • Consolidation of monthly reports and issuance of indicators

Origin of actions

Recommendations for biweekly inspections; Geoconsulting recommendations; special or cross inspections; actions to implement the Emergency Plan; Cross-check; compliance with legal requirements; decommissioning; environmental area; operational life

SIGBAR’s “Traffic light” is the way we monitor the stability of structures and all associated action plans.

Golden rules


Nexa Resources in all its operations has adopted 7 golden rules that aim to guarantee the management of geotechnical structures and the safety of all employees and third parties, they are:

1- Project

Build geotechnical structures only with detailed projects, and any modification to the project can only be carried out with prior approval from the designer/ATO and knowledge of the external consultant, responsible for dams at the unit and corporate team.

2- Licences

Authorize any construction, heightening, corrective maintenance and operation activities only after issuing the necessary licenses. When applicable, communicate to the responsible supervisory body.

3 – Nexa's management system

Comply, in accordance with the Nexa’s management system, with the Operation, Maintenance and Supervision manual (OMS) and keep it updated according to the current operation scenario, physical characteristics of the dam/deposit and the organizational structure. Any change must be approved by the technical person responsible for the structure, external and corporate consultant.

4 - Communication and notification flowchart

Communicate, in accordance with the communication flowchart of the geotechnical structure in this Operation, Maintenance and Supervision manual (EC<=6) or in the emergency action plan (EC=10), identified anomalies or instrument readings with abnormal levels.

5 – Data management

Never manipulate, alter or falsify inspection and monitoring data or replicate data from previous months as being from the current month.

6 – Supervision and audit

Comply with all recommendations of the monthly security assessment with priority and high risk, cross checks, legal demands and audits (DCE/DCO/Legal requirements with classification of greater or extreme severity), within the deadline or if requested by a new deadline, being aware of the business and sustainability directors.

7 – Environmental accident communication

Immediately report environmental accidents greater than or equal to level 4 and/or potential severity greater than or equal to 5, infraction and inspection notices, to the relevant and/or corporate body in accordance with company standards

Application of the golden rules

Failure to comply with any rule, standard or procedure for dams and deposits must be reported and analyzed by the audit team.

Corrective measures will depend on the severity of the violation and other relevant circumstances, determining the appropriate response which may include, but is not limited to:

1 – Strengthen compliance training, education or coaching;

2- Verbal or written warning;

3 – Suspension; or

4 – Termination of the employment contract

Denunciation and evaluation
The denunciation channel is the ethical line, this channel is impartial and transparent, guarantees the confidentiality of information, and preserves the identity of the people involved.

Through it, it is possible to clarify doubts of interpretation, submit reports of non-compliance with the golden rules for dams and deposits, and follow up on a report that has already been filed.

The sending of a report (anonymous or not) can be done through the link or by phone:


0800 892 0741


1 855 888 9926 / 1 885 350 9393


800 201 11


0800 50 000 / 0800 50 288


1 855 8889926


0800 200 288

Reports can also be made directly to the immediate managers to carry out the treatment of the irregularities observed.

Reuse of tailings

In Morro Agudo, we transform all tailings into a secondary product, Agricultural Lime Powder (PCA), which gives rise to Zincal200. The tailings from the operation is sedimented, some being reused in the plant, some sold as Zincal, a product used in agriculture to reduce soil acidity and increase productivity. In 2019, we started selling more Zincal than the volume produced at the unit, which allowed us to reduce the volume of old tailings stored.

Last year, we surpassed the mark of 1 million tons of limestone sold and doubled the reprocessing of old tailings at the plant. In addition to representing revenue of around US$8.7 million (15% of the unit’s total), the process eliminates the need to build new containment structures such as dams, resulting in economic and environmental gains.


In 2019, we installed the most modern siren system in the ZAS* (Self-Rescue Zone) areas, with a sound intensity of 70 dB, in all units in Brazil, in the metallurgy and mining sectors.

Our mass evacuation system has voice resources (pre-recorded and speakerphone) and not just audible alerts, having greater efficiency, eliminating any possibility of confusion, minimizing panic and restoring order, bringing safety to the population.

We use OMNI-360º sirens, specifically for open areas and with completely autonomous operation powered by a photovoltaic system (solar energy).

Regardless of the direction of the winds, the sound continues to be propagated in all directions within the area of ​​interest.

The acoustic project includes sirens with 360° propagation, whose system robustness has been proven over the last 35 years, with more than 20,000 sirens installed in 50 countries around the world.

The system is STI certified (SPEECH INTELLIGIBILITY INDEX) and meets the International Standards ISO 9921 (ERGONOMICS – ASSESSMENT OF SPEECH COMMUNICATION) of 2003, which attests to it being one of the best known worldwide in terms of clarity in voice emission.

Our system is called SI TEST®, which is activated automatically once a day, without disturbing communities in protected areas. In this test, each amplifier, speaker driver, battery charger, battery bank is individually checked for the existence of a radio signal, indicated by an alarm, registered in the Control Center.

In addition, an audible test is carried out daily as a second test to verify the functioning of the system.

The sirens are in accordance with the requirements of new Brazilian legislation, which provides for a range of 10 kilometers or a flood wave equal to 30 minutes. We are currently in the process of automating the monitoring of geotechnical instrumentation. In addition to the online monitoring required by law, we carry out biweekly on-site inspections.


Três Marias

Três Marias

Raising of Módulo Oeste I and Módulo Central of the Murici Tailings Deposit – DRM.

Nexa invites you to the Public Hearing for licensing of the Project Raising the Modules Oeste I and Central of the Murici Tailings Deposit – DRM.

Date: November 23, 2021

Time: 7 pm
To watch the public hearing, click here 

Physical access points will be made available to broadcast the audience with limited capacity, following the rules for preventing and combating Covid-19, in the following locations:

Três Marias Multi-Sports Gymnasium, Três Marias / MG.

Olinto Gonçalves de Melo Municipal School, Beira Rio neighborhood, São Gonçalo do Abaeté / MG.

Information on how to participate, click here.                 

Administrative case No. 1370.01.0046119/2021-52, before the Regional Environmental Superintendency, SUPRAM.