Simply put, pushbacks are a sequence of controllable stages that can be exploited with the mining equipment currently in use and that can satisfy operational and geotechnical mining constraints. In the design and optimisation of open pit mines, pushbacks are extremely important. Since the underlying set of pushbacks serves as the basis for production scheduling, the way pushbacks are chosen, planned, and designed has a significant influence on the mine’s profitability.
What are pushbacks in mining?
Pushbacks, also known as phases, stages, or cutbacks, are defined as a series of manageable, spatially contiguous zones or volumes within an open pit mine that are mined sequentially or in parallel as the pit expands. Each pushback represents a practical mining phase, designed to be exploited with available equipment and to meet operational, geotechnical, and geometric constraints such as minimum mining width, slope angles, and access requirements.
A pushback is typically large enough to be mined bench by bench, ensuring that the operation is feasible and efficient for the scale of equipment and production targets at hand. The boundaries of a pushback are planned to avoid leaving behind unmineable remnants and to guarantee continuous access to all active mining areas.
Why are pushbacks used?
Pushbacks are essential in open pit mining for several key reasons:
- Manageability and operational efficiency
Breaking the ultimate pit into smaller, sequential pushbacks makes the mining process more manageable. It allows for better control over equipment deployment, scheduling, and resource allocation, thus improving operational efficiency. - Economic optimization and profitability
Pushbacks are designed to maximize Net Present Value (NPV) by enabling earlier access to high-grade ore zones. This approach generates revenue sooner, reduces financial risk, and optimizes cash flow over the mine’s life. Mining the entire final pit at once would require removing large amounts of waste before reaching ore, delaying revenue and reducing NPV. - Geotechnical stability and safety
Properly designed pushbacks ensure pit wall stability by adhering to slope and geometric constraints. This reduces the risk of slope failures and improves the overall safety of the operation. - Flexibility and risk management
Pushbacks provide flexibility to adapt to changing economic conditions, such as fluctuations in commodity prices or operational costs. By committing only to the current pushback, a mine can reassess and adjust its plans before moving to the next phase, thereby managing financial and operational risks more effectively. - Grade control and plant requirements
Pushbacks are planned to deliver ore that meets the processing plant’s grade and tonnage requirements, ensuring a steady and predictable feed for downstream operations. - Resource optimization and sustainability
By carefully sequencing pushbacks, mines can optimize resource extraction, minimize waste, and extend the life of the mine, contributing to more sustainable operations.
Pushbacks are thus a foundational element of modern open pit mine planning, directly impacting profitability, safety, and the adaptability of mining operations.
