In the mining industry, gently inclined thin ore bodies are among the most challenging to mine due to their unique geological conditions. These ore bodies are typically limited in mining width, confined in working space, and unsuitable for large-scale mechanized equipment. Given these difficulties, choosing an economical, efficient, and safe mining method is crucial for mining companies. This article will explore how to scientifically and reasonably select mining methods for gently dipping thin ore bodies based on specific conditions to provide valuable references for mining operations.
Understand the Ore Body’s Characteristics
Before selecting a mining method, a thorough understanding of the ore body is essential. Key factors include strike, dip, dip angle, thickness, ore grade, and the stability of the hanging wall and footwall.
Take, for example, an antimony mine in Guizhou Province. The ore body occurs conformably in a stratiform manner along the contact between sandstone and mudstone or limestone. It has a dip angle of 8°–12° and an average thickness of 2.80 meters, falling into the category of stable, moderately thick ore bodies. These characteristics form the basis for selecting an appropriate mining method.
Principles for Choosing a Mining Method
- Safety: Working in confined underground spaces often disturbs the rock stress balance, increasing the risk of roof collapse or wall spalling. Thus, safety must be the top priority.
- Low dilution and ore loss: Recovery and dilution rates directly affect economic viability. A good mining method should maximize ore recovery while minimizing losses and dilution.
- Low cost: While ensuring low dilution and ore loss, the method should also be cost-effective to achieve maximum economic return.
- Simplicity: Prioritize methods with fewer steps, lower development-to-production ratios, high production capacity, and simpler operational management.
Common Mining Methods
Flat-Floor Sublevel Stoping with Pseudo-Inclined Layout
This method removes bottom structures, such as electric rakes and funnels through bottom structure removal, with stage transportation tunnels arranged within the vein. Pseudotilted arrangements are used for cutting uphill tunnels, rock drilling tunnels, and mining blocks, reducing the angle slope between the mining face and the horizontal plane to facilitate the entry of non-tracked equipment such as rock drilling rigs and loaders into the mining area for operations.
Pros:
- Enables mechanized mining
- Simple stoping procedures
- Good ventilation
- Adaptable to irregular ore bodies
Cons:
- Larger exposed roof areas
- Requires artificial supports (e.g., hydraulic props or cemented rock fill)
- Partial or loss due to support zones
Flat-Floor “Z”-Shaped Drift Room-and-Pillar Mining
This method eliminates inefficient scraper loading systems. Sublevel transport drifts are placed within the ore body, and “Z”-shaped drifts are laid out inside the stope for LHDs to operate directly.
Pros:
- High mechanization
- Flexible stope layout
- Low development requirements
Cons:
- Lower ore recovery
- Labor-intensive roof inspection and cleaning
- Higher ore loss rate
Pseudo-Inclined Sublevel Cemented Backfill Mining
In this method, stopes are laid along the strike and divided into sublevel panels and pillars. Pillars are mined first and filled with cemented backfill to form artificial pillars, then the panels are mined.
Pros:
- High mechanization
- Low development requirements
- The short exposure time of voids
- Low ore loss
Cons:
- More complex stoping process
- Cemented fill may increase dilution
- The backfill cycle may lengthen the production time
Conclusion
Selecting a mining method for gently inclined thin ore bodies requires a comprehensive evaluation of safety, efficiency, cost, and environmental impact. By analyzing geological conditions, comparing the advantages and limitations of various methods, and considering real-world production constraints and economic factors, a practical and effective mining solution can be developed.
Among the options, pseudo-inclined sublevel cemented backfill mining stands out for its superior safety, recovery rate, and cost control, making it highly suitable for many gently inclined thin ore bodies. However, as technology advances and ore body conditions evolve, mining methods should also adapt through continuous innovation to meet changing demands and support the safe, efficient, and sustainable development of the mining industry.
