What factors are to be considered to transit from open pit mine to underground mine?

Many ore deposits extend vertically, a fact which is not always known at the start of mining. If initial mining is by opencast methods and ore reserves are proven to greater depths, the pits are often planned to go deeper than originally envisaged. In such cases, surface plants and critical underground facilities: conveyor tunnels, access ramps, ore passes, hoisting, and ventilation shafts are often located much closer to the pit rim and the ore body than desirable. This raises the question of stability, which may be critical for operating the mine longer term. Key considerations to evaluate are: open pit stability, shaft stability, dilution, mud rushes and air blasts, and mining method selection(Planning Considerations For Transition From Open Pit To Underground | SRK Consulting, n.d.).

Below are some factors to be considered when transitioning from an open pit to an underground mine:

• The level of knowledge regarding the deeper areas of the ore body
• Access to personnel with the right skills and experience
• The method and underground mining equipment available 
• Capital cost to establish underground access 
• The time frame to move to full ore underground production 
• Whether ore can be accessed from alternative sources 
• The existing process plant’s capacity to treat what might be different ore types at a lower feed rate 
• The time it takes to establish an underground mine 
• Environmental, safety, and social considerations of open pit mining as opposed to underground mining(Navigating the Open Pit to Underground Mine Process | AMC Consultants, 2023)

Do you know any other factor to be considered? Comment below!

Reference:

• Navigating the Open Pit to Underground Mine Process | AMC Consultants. (2023, May 3). https://www.amcconsultants.com/navigating-the-open-pit-to-underground-mine-process

• Planning Considerations For Transition From Open Pit To Underground | SRK Consulting. (n.d.). Retrieved June 13, 2025, from https://www.srk.com/en/publications/planning-considerations-for-transition-from-open-pit-to-underground