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.

References
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

Modules implemented in 2007

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

Goal

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:

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.

Sirens

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.