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 CO2disposal.
The CO2mineralisation 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 14064‑1‑2021Greenhouse 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 СО2absorption 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 CO2absorbed, 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 СО2absorption 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.
