Managing Tailings Facilities

Management of Operated Tailings Facilities

In August 2020, Global Tailings Review (GTR) formulated the Global Industry Standard on Tailings Management (GISTM). The International Council on Mining and Metals (ICMM) is committed to compliance with GISTM, and as a member of ICMM, we are responding to the standard.
Our Group thoroughly implements measures to prevent significant environmental accident at closed mines that it manages and tailings facilities managed by CBNC and Taganito HPAL Nickel Corporation (THPAL), both of which are located in the Philippines.
In FY2023, we disclosed information concerning high-risk tailings facilities in accordance with the provisions of the GISTM, established a working group under the Environmental Preservation Subcommittee, and took measures to ensure compliance with the GISTM.
On August 1, 2024, we formulated the Sumitomo Metal Mining Group’s Tailings Facility Management Policy based on the GISTM in order to clarify guidelines concerning governance and implementation structures, principles, allocation of management resources, collaboration, preparations for and responses to emergency situations, reviews, and disclosures. In this policy, we make a commitment to securing the resources necessary for conducting tailings facility management activities, cooperating with stakeholders including local communities, mitigating risks throughout the lifecycle from tailings facility planning to decommissioning, and reducing impacts on the environment, as well as providing support for the safety management of tailings facilities at mines and other facilities in which we have invested.

Rehabilitation

CBNC and THPAL produce intermediates for electrolytic nickel and nickel sulfate. At tailings facilities, the slurry after the recovery of nickel through the production process is treated through neutralization to eliminate toxins and precipitate heavy metals. The treated slurry is then pumped to the tailings facilities where it allows the solids to settle down.
CBNC has three tailings facilities and THPAL has one. The CBNC #1 tailings facilities reached its storage capacity and completed its role, and accordingly, we are rehabilitating the site to establish an independent and sustainable ecosystem. Rehabilitation does not simply mean greening, but also making it possible for the area to return into its original state which is conducive to sustaining a natural ecosystem. This involves agroforest technology wherein the forest is established alongside agricultural farming. Thus, vegetables and fruits are also grown in the area. Many local residents and indigenous people are involved in this work, and rehabilitation plays an important role in creating local employment. We perform regular monitoring, and safe and effective management of tailings facilities throughout their lifecycles is confirmed by independent organizations and other concerned parties.

Managing Decommissioned and Closed Mines

We manage the nine decommissioned and closed mines and the associated tailings facilities in Japan indicated in the table in the following page.
Wastewater from mines is generated from mine tunnels and talings facilities where tailings and other materials were accumulated during mine operations. Such wastewater is primarily acidic and contains heavy metals, and as a result, it is properly treated at a water treatment facility before release.
We conducted assessments of accumulation sites in accordance with statutory management standards, which were revised following the Great East Japan Earthquake in 2011, and through 2018 we invested a total of approximately JPY4.5 billion to strengthen the 11 tailings facilities that failed to meet the standards. As a result, all accumulation sites now satisfy the standards.
In addition, we have responded to the increasing severity of natural disasters in recent years by completing the installation of emergency power generation equipment at each site and taking other measures by FY2023 to prepare for interruption of external power supplies and discontinuation of traffic for up to three days.
Accordingly, going forward, we will continue to soundly manage closed mines while also engaging in facility and infrastructure strengthening and improvement.

■ Management Framework for Decommissioned and Closed Mines