GRI 103-2, 103-3 SDG 6.a, 9.4
Water is an issue of fundamental importance in the global context and also for our operations and, therefore, is one of the material topics that make up our Sustainability Master Plan. For the management of the topic, we have guidelines for the sustainable use of the resource and goals for continuous improvement. Our intention is to achieve, by 2025, a percentage of 75% of recirculation and to reduce the specific use of new water in all operations.
In Cerro Lindo, for example, all the water used comes from recirculation or from the sea – the recirculation index is approximately 90%. Despite being at 2,200 meters altitude, the unit is able to use ocean water because it has a desalination plant, which lets it extract the salt by a process of reverse osmosis and to pump it for a distance of 60 kilometers until the operation. This initiative, pioneered in Peru in the mining sector, represents an important solution to this arid region. We also work with the population to advise on how to store rainwater. GRI 303-1 SDG 6.4
In Vazante, the water treatment of thickeners is currently under study, to be disposed together with the tailings in the Aroeira dam. The proposed technology is to treat the supernatant, so as to recirculate water back into the process.
In 2018, under the Mining Lab program, startups were also selected to optimize the line of studies focused on recirculation. Examples are the process with the potential to treat calcium and magnesium sulfates by means of electrocoagulation and enable the recirculation of water/effluent in the smelter’s units; and the development of new bioflocculants capable of optimizing current effluent treatment systems in the smelter and mining unit.
Water management GRI 303-2
In addition to the challenge for current operations, the new projects also come into being with a different approach to water resources management, focusing on recirculation, where all projects are obliged to start operations with at least a 75% rate, as is the case of Aripuanã.
Within the framework of the guidelines for water management, of particular note were the development of tools to monitor the water balance of the units, the analysis of water use accounting on a regular and preventive basis and the identification of the local water risk to define control, mitigation or contingency.
As a follow-up, initiatives were also developed to elevate recirculation and reduce water abstraction, and a Measurement Master Plan was prepared to optimize water outflow measurements for all units.
Based on the goals to be achieved by 2025, the indicators of percentage of recirculation and specific use of new water (m³/t) are being followed systematically in a corporate database, integrated for the entire company in 2018.
In 2018, we maintained the percentage of water recirculation at 66%, which considers the total volume of water recirculated in relation to all the water used in the process, reducing the specific use of new water to 28 m³/t. Moreover, our water metering master plan initiatives progressed.
We also diagnosed the basic sanitation conditions, focusing on access to drinking water and collection/ treatment of domestic sewage, in the municipalities where we have operations in Brazil and Peru. The objective of the diagnosis was to map strategies for an action plan designed to meet the SDG 6 targets (Drinking water and sanitation).
In order to increase sustainable water use, corporate and operational teams participated in the 8th World Water Forum, the world’s largest water event that was, held for the first time in Brazil (in Brasilia).
We participated as lecturers at the IV Latin American Forum of Engineering and Sustainability, promoted by the Federal University of Tocantins (UFT), an event involving more than one thousand students from Brazil and Latin America. We addressed the importance of the standardization of indicators and risk assessment for the management of water resources in mining and smelting enterprises. We believe our participation was relevant for the integration of technical-scientific knowledge and to bring a practical vision of what an environment engineer does to the students.
Water Capture by Vazante SDG 11.6, 15.1
We are undergoing a period of attention in the Vazante region, not only due to the reduction of rainfall volume in the Santa Catarina River basin, at the lowest level in the last decades, but also because of the dolination phenomenon, which are depressions with characteristic occurrence in karstic soils (rich in limestone). Therefore, we routinely monitor the flow of the Santa Catarina River, conduct piezometric monitoring and we prepared a dolomitic risk management plan. We also support the study being carried out by the Technological Research Institute (TRI) to evaluate the impact of river drainage in the region, work designated by the Public Prosecutor’s Office due to a Term of Commitment we signed.
Because the Santa Catarina River represents one of the main water courses in the region, the Vazante Unit also initiated a major project designed to recover the headwater region of the river, which covers an area of 50 thousand hectares and contains 134 springs.
The works were started in May 2018, with a diagnosis of the hydrographic basin through preliminary surveys of its borders, access roads, registry of springs and local properties, state of conservation of the springs and a photographic inventory.
The project’s initial duration is five years, involving the construction of approximately 114 kilometers of fences to protect the springs and the installation of 26 flow monitoring points. In stage 1 (2018/2019), we prioritized the recovery of four streams forming the Guariroba Stream, one of the main Santa Catarina River tributaries, with the construction of approximately 6.2 kilometers of fences and the installation of a flow monitoring point.
Use of water by source GRI 303-3
Disposal SDG 6.3
An efficient water recirculation program contributes to ensuring not only less fresh water intake but also lower effluent volumes, thus reducing both the risk of an adverse impact on the environment as well as the cost of effluent treatment. Such wastewater should only be discarded after a suitable treatment that guarantees all the required quality parameters. During the year, we allocated 14.8% of the environmental expenses for the treatment of effluents.
River Day GRI 303-1
Due to the low levels of water reservoirs in Brazil, the National Water Agency (ANA) proposed an emergency action to suspend one day’s catchment in the São Francisco River, named River Day, which occurred from January to November 2018. We presented the agency with an alternative idea: to replace the weekly shutdowns with a 14% reduction in water capture during the month, with additional social and environmental actions. Immediate reduction was 10%, with an additional reduction of 4% over 60 days. Thus, the Três Marias unit reached an average reduction of 24.36% of water captured from the river, from 530 m³/h to 401 m³/h.
A number of internal and external actions were taken to reach this level of reduction, among them:
■ Increased water recirculation during the zinc filtration step;
■ Maintenance to eliminate leaks in the production areas;
■ Installation of flow-reducing nozzles in hoses used for cleaning purposes;
■ Change in periodicity (from fortnightly to monthly) for cleaning the administrative offices with hoses;
■ Water blitz, to map the points of waste;
■ Guided tours for schools and the local community, with the distribution of a booklet containing water-saving tips;
■ Awareness raising on websites, radio shows and newspapers about the topic.