Methodology

For the majority of mining operations that are not integrated with a smelter or refinery we have included emissions associated with smelting and refining copper concentrates.

Smelter emission intensities are modelled based on regional benchmarks. Emissions at the smelter are driven by technology, electricity, and consumption of combustibles such as natural gas, diesel and coal. Concentrate shipments are modelled according to export destination based on reported statistics or Skarn's industry expertise.

Default reporting of emission intensities is on a recovered copper-equivalent basis. CO2e emissions are divided by contained copper-equivalent production at the minesite. This allows for a like-for-like comparison between polymetallic mines producing multiple commodities with single product operations. Copper equivalent production is calculated as the volume of each metal multiplied by the average metal price divided by the average copper price for the year in question.

Scope 1 (Direct) Greenhouse Gas Emissions are derived from sources that are owned or controlled by the reporting organisation - often to the 'minegate' boundary or smelter/refinery gate for integrated operations. They typically include emissions from consumption of diesel in haulage trucks or onsite power generators along with emissions from other sources such as natural gas, aviation fuel, fugitive emissions (e.g. coal, lime, cyanide), etc.

Scope 2 (Indirect) Greenhouse Gas Emissions are generated at sources owned or controlled by another organisation. This is generally electricity purchased by the mine (or smelter/refinery for integrated assets) from the grid. The Grid Carbon Factors sheet in this model provides a high level summary of the greenhouse gas content per MWh that a mine might be exposed to. However, this can vary at an asset level which may have contracts in place to purchase a higher proportion of renewable energy than the grid / country average.

Downstream emissions from smelting are based on Skarn's knowledge of material flows from smelter to refinery.

By products and residues

Although there are certain by products from both smelter and refinery that are normally commercialised, we have allocated all CO2 emissions to the production of copper. This means that we do not allocate CO2 emissions to the production of sulphuric acid or slimes. In the case of the former, we will include the emissions associated to electricity consumption in the smelter E0. For anode slimes, since there are no operational changes that can be done to the smelter or to the refinery to increase or decrease the recovery of precious metals, we allocate all emissions to copper.

From Skarn's perspective, the CO2 intensity of slime production at the refinery is 0. The situation changes when these slimes are treated at a precious metals plants, which is where we would allocate CO2 emissions to Gold, Silver and Platinum. The precious metals plant emissions are not included in the boundaries of our analysis.

*As defined by the GHG Protocol Corporate Accounting and Reporting Standardhttps://ghgprotocol.org/corporate-standard.