Gold
- Data is presented from the mine perspective, including supply chain emissions up to production of refined gold
- Physical production parameters are presented, including ore mined, heap leached and/or milled, ore grades, strip ratios and by-product metal production
- For base metal concentrates containing gold, emissions are fully allocated to the primary metal in concentrate with gold being free-carried, up to the anode slime stage. Emissions from refining of anode slimes are allocated to gold
- Allocation of emissions by company is added according to equity ownership of mine assets, including emissions for minority shareholdings, which are often excluded from company sustainability reports)
- The dataset includes total cash costs and all-in sustaining costs, based on the World Gold Council Guidelines
Emission data is presented as both total tonnes of CO2e and tonnes of CO2e per equivalent ounce of refined gold.
For gold, E0 and E1 emissions are defined as follows:
E0: Scope 1 and 2 emissions at mine site.
E1: E0 plus emissions from dore and concentrate freight, smelting and refining.
Methodology
Base metal smelting/refining emissions - For mines that produce gold in a base metal concentrate, we have assumed that all the emissions relating to the freight, smelting and refining of the concentrate are apportioned to the primary metal in that concentrate (i.e. copper in a copper concentrate) - therefore gold is effectively 'free carried' However, emissions from refining of anode slimes derived from the smelting of concentrates have been calculated and included in Smelting / Refining.
Ore grades are presented based on the total ore leached and/or milled. Company and country averages are weighted by total ore treated (leached and/or milled) and attributable ownership.
Waste to ore strip ratios - ratios have been calculated as the waste to ore treated for open pit mines. Simplistically, a high strip ratio can potentially incur higher diesel consumption and therefore lead to a higher emission intensity.
Energy consumption metrics- the majority of CO2 emissions created in gold mining are from consumption of fossil fuels, namely diesel used in haulage. Data in the accompanying model allows users to compare the energy use and efficiency of each mine (or company) and relationship between energy use and carbon emissions. The majority of Skarn's data is derived from reported information where energy use and carbon emissions are verified and reconciled. However, many companies often use differing calorific values or emission factor constants which can lead to relatively modest discrepancies - Skarn makes an attempt to balance these discrepancies and highlight where numbers have been 'corrected' or adjusted. A summary of direct energy by source split is provided on the AssetData, CompanyData and CountryData sheets - diesel energy includes diesel and biodiesel used in haulage and onsite power generation.
Energy emission factors - Calculated or reported emissions divided by energy. The lower the emission factor the greater the consumption of renewable energy; typically mines that have a direct emission factor below 50tCO2e/TJ often generate a notable proportion of renewable energy onsite (hydro, solar). Mines with a direct emission factor of >80tCO2e/TJ tend to generate heat or electricity onsite from coal. In the case of Beatrix the very high factor relates to the fugitive methane release which is incorporated in Scope 1 emissions. Electricity- data included in the accompany model relates to the MWh of electricity (and heat) purchased from the electricity grid and onsite power generation. This data is presented in terrajoules (TJ) and in kWh/t ore treated. Reagent consumption - where companies report consumption of lime, cyanide, caustic soda and explosives, Skarn has captured this data in the accompanying AssetData sheets.
Total Cash Costs and All-in Sustaining Costs:
Costs are presented for reference only.
Costs are presented as reported and may include a Total Cash Costs per sales or production ounce. In general most costs are based on the World Gold Council guidelines - https://www.gold.org/about-gold/gold-supply/responsible-gold/all-in-costs.
Mines where costs are zero or missing are generally operations that are classified as primary copper or primary silver mines. For these operations we have excluded costs from our database.
All-in Sustaining Costs $/oz are presented as reported but in certain cases maybe adjusted to include corporate overheads / general administration charges which may be omitted from company reported numbers.
AISC Cost Quartile Position - a summary of the relative global cost position, ranked on All-in Sustaining Costs, for each mine, company or country. For example, 4th quartile mines and companies are those which have the highest cost compared to the rest of the gold mining industry and where at least 75 percent of production has a lower cost.