Norilsk Nickel starts to study the ability of waste rock to absorb greenhouse gases

The company has set an ambitious goal to reduce greenhouse gas emissions, and one of the ways to achieve this goal is to study the process of absorption of greenhouse gases by the rock and develop a methodology how to account for captured carbon units.
In 2021, the company mined 41.2 million tons of ore. In the process of mining and beneficiation of ore at the company's enterprises, waste rock, or tailings, are formed, which is a finely divided rock with a fraction of less than 0.4 mm, similar to fine sand. In the form of waste, tailings are stored at special landfills - tailing dumps.
Silica and magnesium oxide contained in such a rock are able to absorb carbon dioxide during weathering - prolonged contact with atmospheric air. When interacting with water and air, carbon dioxide binds with minerals and metals that are present in the composition of such rocks, resulting in the formation of carbonates. This process is called mineralization. As a result, CO2 from the atmosphere passes into secondary minerals in the form of carbonates.
According to Norilsk Nickel's environmental strategy, greenhouse gas emissions in the first and second scopes (direct emissions from production and indirect emissions from energy consumption) for the group should decrease by 25% by 2028, to 7.7 million tons per year compared to 10 .3 million tons now.
Taking into account the company's large production volumes, the potential for CO2 absorption from the atmosphere by the waste rock can reach several million tons per year. The Technological Innovation Department of Norilsk Nickel has begun assessing this potential. The specialists of the department, together with the production sites of the group, collected 200 samples to study the processes of natural and artificial mineralization of waste rock. Then the specialized research institute will analyze the mineralogical and elemental composition of the collected samples with an assessment of the content of absorbed CO2.
Performing drilling operations and obtaining samples of tailings for the study of the mineralization process
“We started to study the process of mineralization. The plans include developing a methodology for assessing and calculating carbon units based on the results obtained, which will become the basis for creating a standard for accounting for carbon units. As a result, we will get a methodology that will allow us to evaluate the absorption capacity of tailings based on the mineralogical composition of a ton of ore mined. Thanks to this, we will understand how many tons of ore have been processed and how much CO2 has been absorbed,” commented Sergey Vagner, Head of the Technologies for Recycling and Involving By-Products section of the company’s Department of Technological Innovations.
Together with scientists, Norilsk Nickel is also developing a technology for artificial tailings mineralization. It can be used at the company's production sites: for example, it will be possible to pass flue gases from thermal power plants or process gases from melting furnaces, which also contain CO2, through the pulp. This will significantly increase the potential for absorption of greenhouse gases.

Vladimir Malakhov, Rough&Polished