Decarbonisation projects

Mineralisation of mining waste

Research into the mineral sequestration of carbon dioxide has been under way since the late 20th century, but has significantly intensified over the past two decades due to the global search for safe, environmentally sound, and long‑term solutions for CO₂ disposal.

The CO₂ mineralisation process implies the reaction of carbon dioxide with various minerals – such as olivine, serpentine, and other silicates containing calcium, magnesium, and iron. During the reaction, a carbon dioxide molecule binds with the positively charged ions of these elements in the presence of water to form carbonates, thereby converting into a solid phase.

In 2024, TÜV AUSTRIA validated Nornickel’s methodology for calculating direct GHG absorption through gangue mineralisation in tailings storage facilities to GOST R ISO 14064‑1‑2021 Greenhouse gases.

Part 1. Specification with guidance at the organisation level for quantification and reporting of greenhouse gas emissions and removals. This methodology is unique in Russian practice.

The methodology provides for measuring СО₂ absorption through passive (non‑anthropogenic) carbonation of certain minerals in the tailings stored at the Company’s tailings storage facilities. The rate of passive carbonation depends on the mineral composition of the parent ore, particle size, climatic conditions, and the chemistry of pore water in the rock mass. One of the key factors influencing the efficiency of the mineralisation process is the acid–alkaline balance of the solution in which the reaction occurs. To estimate the amount of CO₂ absorbed, analytical methods are used, including infrared (IR) spectroscopy, X‑ray diffractometry, and CHNS(CN) elemental analysis, which determines the carbon content in the pulp and tailings.

The amount of direct СО₂ absorption depends on the volume of waste rock disposed of at the Company’s tailings storage facilities in the reporting period. The amount of actual removals for 2021–2024 was verified by TÜV AUSTRIA.

Nornickel plans to further develop this project, with studies of artificial and active gangue mineralisation in tailings storage facilities scheduled to start as early as 2025. These approaches have greater potential for greenhouse gas capture compared to natural mineralisation.