Abstract: Under the Carbon Peaking and Carbon Neutrality Goals strategy,open-pit mining is advancing toward green,
low-carbon,and sustainable development. This study develops a process-wide carbon-accounting framework for open-pit operations,
integrating direct emissions (electricity and fossil-fuel use,explosives,and mineral processing) and indirect emissions
(loss of ecosystem carbon-sequestration capacity due to land disturbance,plus the embodied carbon of construction materials).
A large open-pit iron mine is used as a case study to quantify how the ultimate pit limit (UPL) scale and pit-wall slope-angle
schemes jointly shape total emissions,emission composition,and economic performance. Total emissions increase approximately
linearly with pit expansion and tend to accelerate at larger scales. In terms of composition,direct emissions contribute 96. 2% to
96. 8% of the total,with mineral processing as the dominant source (54% to 68%),whereas indirect emissions account for
3. 2% to 3. 8% and are mainly driven by sequestration loss from pit-area land disturbance (1. 61% to 1. 88%). Steepening pitwall
angles improves economic performance;meanwhile,total emissions exhibit marked non-linear fluctuations across adjacent
slope-angle schemes,with a maximum difference of 0. 427 Mt CO2. Despite these changes in magnitude,the relative shares of
major emission categories remain broadly stable across schemes. Overall,the case mine exhibits an emission intensity of
0. 044 9 t CO2 per tonne of ore under the accounting boundary and assumptions adopted in this study. Beyond providing a
transparent emissions inventory,the proposed framework supports design-stage screening and comparison of alternative pit limits
and slope-angle configurations. It also offers a quantitative basis for further decision-making extensions,such as internalizing
carbon costs into economic evaluation or identifying Pareto-efficient trade-offs between economic returns and emissions. These
capabilities allow environmental constraints to be incorporated proactively into mine design,thereby facilitating low-carbon
planning and sustainable development of open-pit mines.