Stoping Methods-I in Underground Metal Mining

Stoping methods play a crucial role in underground metal mining operations. These methods involve the extraction of ore from a mine by creating open spaces or stopes. The selection of the appropriate stoping method is essential for maximizing productivity and ensuring the safety of miners. In this topic, we will explore different stoping methods used in underground metal mining and discuss their applications, advantages, and disadvantages.

Key Concepts and Principles

Overhand Stoping Method

The overhand stoping method is a common technique used in underground metal mining. It involves mining from the top downwards, removing the ore in horizontal slices. This method is suitable for steeply dipping ore bodies and provides good access for mining equipment and personnel.

Advantages of Overhand Stoping Method

• Efficient extraction of ore from steeply dipping ore bodies
• Provides good access for mining equipment and personnel
• Allows for easy control of dilution and ore recovery

Disadvantages of Overhand Stoping Method

• Requires additional support to prevent cave-ins
• Increased risk of rock falls
• Limited flexibility in mining sequence

Underhand Stoping Method

The underhand stoping method is the opposite of the overhand method. It involves mining from the bottom upwards, removing the ore in horizontal slices. This method is suitable for weak or unstable ore bodies and provides better control over dilution and ore recovery.

Advantages of Underhand Stoping Method

• Better control over dilution and ore recovery
• Suitable for weak or unstable ore bodies
• Reduced risk of rock falls

Disadvantages of Underhand Stoping Method

• Limited access for mining equipment and personnel
• Increased difficulty in controlling cave-ins
• Lower productivity compared to overhand stoping

Breast Stoping Methods

Breast stoping methods involve mining ore from a vertical or near-vertical face. This method is commonly used when the ore body is narrow and steeply dipping. There are different variations of breast stoping methods, including longitudinal, transverse, and inclined breast stoping.

Advantages of Breast Stoping Methods

• Efficient extraction of ore from narrow and steeply dipping ore bodies
• Provides good access for mining equipment and personnel
• Allows for easy control of dilution and ore recovery

Disadvantages of Breast Stoping Methods

• Requires additional support to prevent cave-ins
• Increased risk of rock falls
• Limited flexibility in mining sequence

Open Stoping Method

The open stoping method involves mining ore from an open stope, which is a large underground excavation. This method is suitable for large, near-vertical ore bodies and provides high productivity and flexibility in mining sequence.

Advantages of Open Stoping Method

• High productivity and flexibility in mining sequence
• Suitable for large, near-vertical ore bodies
• Provides good access for mining equipment and personnel

Disadvantages of Open Stoping Method

• Requires extensive support to prevent cave-ins
• Increased risk of rock falls
• Higher operational costs compared to other methods

Vertical Crater Retreat (VCR) Method

The vertical crater retreat (VCR) method is a specialized stoping method used for mining large, steeply dipping ore bodies. It involves drilling a series of vertical holes in the ore body and blasting the ore in a controlled manner. The blasted ore is then mucked out and transported to the surface.

Advantages of Vertical Crater Retreat Method

• Efficient extraction of large, steeply dipping ore bodies
• Provides good control over dilution and ore recovery
• Allows for selective mining of high-grade ore

Disadvantages of Vertical Crater Retreat Method

• Requires specialized drilling and blasting equipment
• Increased risk of ground instability
• Higher operational costs compared to other methods

Sublevel Stoping Method

The sublevel stoping method is commonly used for mining large, tabular ore bodies. It involves the extraction of ore in a series of horizontal slices or sublevels. This method provides good access for mining equipment and personnel and allows for selective mining of high-grade ore.

Advantages of Sublevel Stoping Method

• Suitable for mining large, tabular ore bodies
• Provides good access for mining equipment and personnel
• Allows for selective mining of high-grade ore

Disadvantages of Sublevel Stoping Method

• Requires extensive support to prevent cave-ins
• Increased risk of rock falls
• Limited flexibility in mining sequence

Room and Pillar Method

The room and pillar method is a traditional stoping method used for mining coal and other sedimentary deposits. It involves the extraction of ore in a grid-like pattern, leaving behind pillars of ore to support the roof. This method provides good access for mining equipment and personnel and allows for selective mining of high-grade ore.

Advantages of Room and Pillar Method

• Suitable for mining coal and other sedimentary deposits
• Provides good access for mining equipment and personnel
• Allows for selective mining of high-grade ore

Disadvantages of Room and Pillar Method

• Lower recovery of ore compared to other methods
• Requires extensive support to prevent roof collapse
• Limited flexibility in mining sequence

Resuing Method

The resuing method is a stoping method used for mining narrow, steeply dipping ore bodies. It involves mining the ore in a series of horizontal slices, leaving behind pillars of ore to support the roof. This method provides good access for mining equipment and personnel and allows for selective mining of high-grade ore.

Advantages of Resuing Method

• Efficient extraction of ore from narrow, steeply dipping ore bodies
• Provides good access for mining equipment and personnel
• Allows for selective mining of high-grade ore

Disadvantages of Resuing Method

• Requires extensive support to prevent roof collapse
• Increased risk of rock falls
• Limited flexibility in mining sequence

Summary

Stoping methods are essential in underground metal mining operations for extracting ore from the mine. The overhand stoping method involves mining from the top downwards, while the underhand stoping method involves mining from the bottom upwards. Breast stoping methods are used for mining ore from a vertical or near-vertical face, and open stoping involves mining ore from an open stope. The vertical crater retreat (VCR) method is used for mining large, steeply dipping ore bodies, and the sublevel stoping method is used for mining large, tabular ore bodies. The room and pillar method is used for mining coal and other sedimentary deposits, and the resuing method is used for mining narrow, steeply dipping ore bodies.

Analogy

Imagine you are building a sandcastle on the beach. You can choose different methods to shape the sandcastle, such as starting from the top and working downwards or starting from the bottom and working upwards. Similarly, in underground metal mining, different stoping methods are used to extract ore from the mine, depending on the characteristics of the ore body.