Tailings, Residue, Water and Waste Rock Management System

What is SIGBAR?

What are SIGBAR and SIGDEP? SIGBAR is a Dam Management System developed by Geoconsultoria, aimed at ensuring the stability of dams, and SIGDEP is a Tailings Deposit Management System, so that any potential weaknesses are reported in advance, allowing for preventive actions.

MODULES

Each module serves to standardize a single way of acting.

REFERENCES

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

We use processes and procedures that comprise the Integrated Dam Management System (SIGBar).

This system consists of 12 modules that establish the rules and measures for periodic monitoring activities, based on which we control all of the structures. SIGBar establishes guidelines for managing documents, monitoring activities, evaluation, risk analysis, compliance with rules and legislation, training of the workforce, structure operations, and other provisions.

This work is monitored on an ongoing basis by an independent firm, which receives data from inspections performed every fifteen days and consolidates data from all monitoring activity to issue monthly stability reports.

Módulos implantados desde 2007

Módulos implantados desde 2007

Origin of the actions

Recommendations for twice-monthly inspections; recommendations from Geoconsultoria; special or cross inspections; actions for deploying the Emergency Plan; Cross-check; compliance with legal requirements; decommissioning; environmental area; operational life.

The “TRAFFIC LIGHT” is the way for us to monitor the stability of the structures and all associated action plans.

Golden rules

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

1 – Project

Build geotechnical structures only with detailed projects, and any modification in the project can only be done with the prior approval of the designer/ATO and the awareness of the external consultant, responsible for dams in the unit and corporate.

2 – Licenses

Authorize any construction activity, dam raising, corrective maintenance work and operation only after the necessary licenses have been issued. When applicable, notify the responsible inspection agency.

3 – Nexa management system

Comply, according to the Nexa management system, with the Operation, Maintenance and Supervision (OMS) manual and keep it updated according to the current operation scenario, physical characteristics of the dam/pond and organizational structure. Any change must have the approval of the structure’s technical manager, external and corporate consultant.

4 – Communication and notification flowchart

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

5 – Data Management

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

6 – Supervision and Auditing

Attend to all recommendations of the monthly safety assessment with priority and high risk, cross checks, legal demands and audits (DCE/DCO/Legal requirements with classification of major or extreme seriousness), on time or if requested new deadline have the awareness of the business and sustainability directors.

7 – Communication of Environmental Accidents

Immediately communicate 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 pertinent and/or corporate entity, according to the company’s standard.

Application of the golden rules

The non-compliance with any rule, standard, or procedure for dams and deposits must be reported and analyzed by the audit team.

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

Reuse of Tailings

In Morro Agudo, we transformed all the tailings into a secondary product, Agricultural Limestone Powder, from which Zincal200 is derived. The tailings from the mining operation are sedimented, part of which is reused in the plant and part of which is sold as Zincal, a product used in agriculture to decrease soil acidity and increase yields. In 2019, we began selling more Zincal than the volume produced at the unit, which allowed us to reduce the stockpiles of old tailings. Last year, we passed the milestone of one million metric tons of limestone sold, and doubled the reprocessing of old tailings at the plant. Aside from representing revenue on the order of US$ 8.7 million (15% of the unit’s total revenue), the process eliminates the need to build new containment structures such as dams, resulting in economic and environmental gains.

Sirenes

In 2019 we installed the most modern siren system in the areas of the Self-Rescue Zone*, with a sound intensity of 70 dB, at all units in Brazil, in the metallurgy and mining sectors. Our mass evacuation system has not only sound alerts but also voice resources (both pre-recorded and live-voice), which offers greater efficiency and eliminates any possibility of confusion, thus minimizing panic, restoring order, and bringing safety to the local populace. We use OMNI-360º sirens, specifically designed for open areas and with completely autonomous operation, powered by a photovoltaic system (solar energy).

Regardless of the wind direction, the sound continues to be propagated in all directions within the area of interest. The sound design includes sirens with 360° propagation, and the system’s robust performance has been proven throughout 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 Standard ISO 9921-2003 (ERGONOMICS – ASSESSMENT OF SPEECH COMMUNICATION), which is one of the world’s best known standards regarding clarity of voice emission.

Our system is called SI TEST® which is activated automatically once a day, without disturbing the communities in the protected areas. In this test, each amplifier, speaker driver, battery charger, battery bank, and radio signal are checked individually, being indicated by an alarm registered in the Control Center. Additionally, an audible test is performed daily, as a second test to verify system operation. The sirens are in accordance with the requirements of the latest Brazilian legislation, which provides for a range within a radius of 10 kilometers or a flood wave equal to 30 minutes. We are currently in the process of automating the geotechnical instrument monitoring process. In addition to the online monitoring required by law, we conduct onsite inspections every 15 days.