What is Cave Mining?
Cave mining, for those who are new to the term, is a highly specialized, large-scale method of underground mining used to extract large orebodies efficiently.
The main principle behind cave mining is to undercut the orebody using drilling and blasting over a wide area and then allow it to collapse under its own weight. This process continues until a fully fragmented column is created, which is similar to a massive silo. The caved ore can now be drawn at a high rate of production, typically with large capacity LHD units. Once the cave reaches the surface, a subsidence zone is created. This method is particularly effective for large, low-grade deposits, where traditional mining methods would not be economic.
In this article, we’re going to examine the different types of cave mining, their key features, advantages, and challenges, and the key players involved in this unique industry.
Different Types of Cave Mining: An Overview
Cave mining methods have grown and evolved to suit various geological conditions and ore body characteristics. Let’s explore each type in more detail:
Block Caving
Block caving is the most widely used cave mining method, particularly for large, low-grade, and vertically extensive ore bodies. An orebody may be divided into a series of block caves on the same level or at different levels. Small orebodies may comprise of only one block cave.
Figure 1: Block caving schematic
Block caving generally follows the typical sequence of:
- Undercutting
- Drawpoint development
- Drawbell blasting
- Cave establishment: Initiation and production ramp-up
- Full cave production
The combination of comminution and induced stresses on the fractured rock in the orebody block results in a column of fragmented rock particles. By pulling out this broken ore from a series of Drawpoints at the base of the block cave, an expansion void is created which, in turn, is refilled with cave ore from above.
Key features:
- A large block of ore with an area that can range between 2-20 Ha and between 100-500 meters in height, is undercut to initiate caving.
- The undercut level is created by developing a network of tunnels and then blasting above these to remove a horizontal slice of rock.
- Below the undercut level, a production level (or extraction level) is developed by drill & blast to create a network of drawbells and drawpoints.
- As the undercut advances, the ore above begins to fracture and cave under its own weight and induced stresses.
- The fragmented ore is then drawn down through the drawpoints and delivered to the materials handling system.
Advantages:
- High production rates (can exceed 100,000 tonnes per day)
- Low operating costs once the initial development and construction is complete
- Suitable for very large ore bodies
Challenges:
- High initial capital costs
- Long lead times for development (can take 5-7 years before production starts)
- Requires careful planning and monitoring to manage cave propagation
Induced Massive Caving
Induced massive caving is used in very competent rock masses that wouldn’t naturally cave under their own weight.
Key features:
- Large-scale blasting is used to initiate and propagate the cave
- Often used in conjunction with other caving methods
- Requires extensive drilling and blasting networks
Advantages:
- Allows caving methods to be used in rock masses that would otherwise be too competent
- Can improve fragmentation in very strong rock types
Challenges:
- Higher costs due to extensive drilling and blasting requirements
- Requires careful blast design and sequencing to control cave propagation
- Can lead to more unpredictable cave behavior
Panel Caving
Panel caving is a variation of block caving, where massive ore bodies are divided into large panels that are mined using a continuous process where undercutting, development, drawbell establishment and cave production are carried out simultaneously.
Key features:
- The ore body is divided into discrete panels, typically 100-200 meters wide
- Undercutting, Extraction Level development, Drawbell establishment and production are carried out simultaneously and continually over a period of many years.
- Allows for more controlled extraction and can be used when the entire ore body is too large to be undercut in one block.
Advantages:
- More flexible than block caving for large orebodies, allowing for phased development
- Can be used in ore bodies with varying grade distribution
- Allows for earlier production start compared to full block caving
Challenges:
- Requires careful sequencing of panels to manage stress redistribution
- Can be more complex to manage than block caving due to the various simultaneous activities
Sublevel Caving
Figure 2: Sublevel Caving layout (after Mining Methods in Underground Mining, Atlas Copco 2007)
Sublevel caving is used for steeply dipping ore bodies with competent host rock. It’s a top-down method that combines some aspects of caving with more traditional sublevel stoping.
Key features:
- The ore body is divided into sublevels, typically 15-30 meters apart vertically spaced.
- Mining progresses from the top down with each sublevel being blasted and the broken ore is trammed to orepasses using LHD units.
- Ore is drawn from each sublevel as mining progresses downwards with a percentage of ore left to control draw and to assist in minimizing any air gap.
- Waste material is allowed to cave above the ore to prevent an airgap developing.
Advantages:
- More selective than block caving, allowing for better grade control
- Can be used in narrower, more steeply dipping ore bodies
- Lower initial capital cost compared to block caving
Challenges:
- Higher operating costs than block caving due to drilling and blasting of all ore
- Lower production rates compared to block caving
- Can have higher dilution rates as mining progresses deeper
Sublevel Shrinkage
Figure 3: Sublevel Shrinkage with continuous backfill schematic (after: Brand and Haider, 2023, Sublevel Shrinkage (SLSh) Mining—A State-of-the-art Review)
Sublevel shrinkage is a variant of cave mining that combines elements of sublevel caving and shrinkage stoping, typically used for narrow, steeply dipping ore bodies with competent ore conditions but which may have weak sidewalls that must be restrained from caving by backfilling.
Key features:
- Mining progresses in a top-down sequence
- Approach requires backfilling, using dedicated tunnels to backfill the rock from the top
- Backfilling is necessary to prevent unwanted failure of sidewalls and backs
- Typically uses a series of sublevels spaced 8-15 meters apart
- Utilizes long-hole drilling techniques for ore breakage
Advantages:
- Suitable for narrow, high-grade ore bodies that may not be amenable to other cave mining methods
- Reduced development costs compared to traditional cut-and-fill methods
- Better ore recovery and less dilution compared to sublevel caving
Challenges:
- Implementing a backfill delivery system, developing dedicated accesses for backfill delivery and maintaining these accesses.
- Limited production rates due to the controlled draw of broken ore
- Requires careful scheduling to balance ore breaking, backfilling and drawing activities
- Risk of oxidation or spontaneous combustion in some ore types when broken ore is left in place
- Potential for hang-ups and bridging in the broken ore, requiring secondary breaking
Global Cave Mining Industry: Statistics and Key Players
The cave mining industry has seen significant growth in recent decades, driven by the need to extract large, low-grade ore bodies economically. Here’s an overview of the global cave mining landscape:
Industry Statistics
- As of 2025, there are approximately 30-35 active large-scale cave mines worldwide
- Block and panel caving account for about 9% of the world’s underground metal production
- The total annual production from cave mining operations globally is estimated to be over 300 million tonnes
- Copper is the most common commodity extracted using cave mining methods, followed by molybdenum, gold, and diamonds
Major Companies and Operations
- Rio Tinto
- Operates the Oyu Tolgoi copper-gold mine in Mongolia, one of the world’s largest block cave mining operations
- Rio Tinto operated the Argyle diamond mine in Australia (from 2008-2020) which used block caving
- Freeport-McMoRan
- Operates the Grasberg copper-gold mine in Indonesia, transitioning from open pit to block cave mining
- Also operates block cave mines at Henderson and Climax in Colorado, USA
- Codelco
- Chile’s state-owned copper mining company operates several panel and block cave mines including El Teniente, the world’s largest underground copper mine and Chuquicamata underground
- Newmont
- Operates the Cadia Valley mine site in Australia, which consists of a series of caves extracting the Cadia East gold-copper orebody
- The Ridgeway Deeps block cave was in production between 2009-2016.
- KGHM Polska Miedź
- Operates the Deep Głogów copper mine in Poland, using a modified room and pillar method transitioning to block caving
- Other companies currently using block/panel caving: Philex, Palabora, Tongkuangyu, Pulang, Evolution, Petra, and New Gold.
Consulting Firms and Research Centers
Several consulting firms and research centers specialize in cave mining:
- SRK Consulting: Offers services in cave mining design, planning, and optimization.
- Itasca Consulting Group: Specializes in numerical modelling for cave mining operations.
- Beck Engineering: Focuses on geotechnical aspects of cave mining.
- Sustainable Minerals Institute (SMI) at the University of Queensland: Conducts research into various aspects of cave mining, including the Mass Mining Technology (MMT) project.
- Helmholtz Institute Freiberg for Resource Technology: Conducts research into innovative mining methods, including cave mining.
The cave mining industry continues to evolve, driven by technological advancements and the need for more efficient and sustainable mining methods.
