Block caving mining method - Epiroc

Summary

Block caving is an efficient large-scale mining method that allows for the extraction of large volumes of rock. The process begins by creating a gap in the lower part of the mine, causing the rock mass to cave due to gravity and stress. While the development time is longer compared to other methods, block caving offers high productivity with low operating costs and is highly mechanized. Substantial rock reinforcement is needed due to extreme rock stress, and ore is extracted via draw points. This method ultimately results in subsidence on the surface, but it ensures high ore recovery and minimal blasting.

Takeaways

• 😀 Block caving is a large-scale mining method that allows efficient extraction of huge volumes of rock.
• 😀 The development time before production starts is longer compared to other mining methods.
• 😀 The process creates a gap by drawing rock from the lower part of the mine, causing the overlying rock to cave due to gravity and rock stress.
• 😀 Accurate drilling and blasting are essential to avoid misfires and ensure effective rock breakage.
• 😀 Rock reinforcement like steel arches, sprayed concrete, cable bolts, and steel mesh is necessary to handle extreme rock stress and long production periods.
• 😀 The ore body needs to be large enough, and the rock conditions must be favorable for natural breakage to ensure successful mining.
• 😀 An undercut level is developed to break the rock mass into smaller pieces, initiating the caving process.
• 😀 Drawbells between the undercut and extraction levels create passages for caved rock.
• 😀 Ore extraction results in subsidence on the surface, provided the rock breaks properly and the ore is extracted evenly.
• 😀 Block caving offers high productivity with low operating costs, making it ideal for mechanization and automation in mining.

Q & A

What is block caving, and how is it used in mining?

Block caving is a large-scale mining method used for efficiently extracting vast volumes of rock. It involves creating a gap by drawing rock from the lower part of a mine, allowing gravity and rock stress to cause the overlying rock to cave. This technique minimizes the need for drilling and blasting.

Why does block caving have a longer development time compared to other mining methods?

Block caving requires a longer development time because it involves preparing the mine with undercut levels and ensuring the ore body is large enough and the rock conditions are favorable for natural breakage, which takes more time to set up compared to other methods.

What are draw bells in block caving, and why are they important?

Draw bells are passages created between the undercut and extraction levels in a block caving mine. They allow the caved rock to flow to the extraction points, which is essential for ensuring the smooth removal of ore throughout the mining process.

What is the role of rock reinforcement in block caving?

Rock reinforcement is critical in block caving due to the extreme rock stress changes and the long duration of the production period. Reinforcements like steel arches, sprayed concrete, cable bolts, and rock bolts are used to stabilize the mine and prevent collapses or misfires.

How does the rock caving process work once the undercut is created?

Once the undercut is created, the rock mass in the lower part of the ore body is broken down into smaller pieces, causing the overlying rock to cave due to gravity and rock stress. This caved rock then flows to the extraction level, where it can be loaded and transported.

What factors influence the choice of transportation method for the extracted ore?

The choice of transportation method depends on factors such as the fragmentation of the ore and the crushing requirements. These factors determine the most efficient way to move the ore to the surface or to a crusher.

What happens to the surrounding rock as ore is extracted in block caving?

As ore is extracted, the surrounding rock eventually caves in, resulting in subsidence at the surface. This natural subsidence occurs as a result of the caving process and is a characteristic of block caving mining.

What are the advantages of block caving as a mining method?

Block caving offers several advantages, including high productivity, low operating costs, and a high degree of mechanization. It also allows for automation, making it a cost-effective and efficient method for large-scale ore extraction.

Why is accurate drilling crucial in block caving?

Accurate drilling is essential in block caving to avoid misfires, which could disrupt the mining process. Precise drilling ensures the proper blasting of the undercut and the smooth flow of caved rock to the extraction level.

What is the significance of having a large ore body in block caving?

A large ore body is essential in block caving because the method relies on gravity and rock stress to break the rock naturally. If the ore body is too small or the rock conditions are not favorable, the caving process may not work effectively, leading to inefficient extraction.