Introduction to Bord and Pillar Method

I. Importance of Bord and Pillar Method in Underground Coal Mining

The Bord and Pillar Method is an underground mining technique used to extract coal. It is one of the oldest and most commonly used methods for coal mining. The method involves the creation of a network of tunnels or 'headings' in the coal seam, which are then divided into smaller sections called 'panels'. These panels are further divided by leaving pillars of coal in between them. The pillars provide support to the roof and prevent the collapse of the mine.

The Bord and Pillar Method is particularly suitable for mining coal deposits that are too deep to be extracted by surface mining methods. It allows for the efficient extraction of coal while ensuring the stability and safety of the mine.

II. Fundamentals of Bord and Pillar Method

The Bord and Pillar Method is based on the principle of leaving behind pillars of coal to support the roof of the mine. The pillars act as a barrier between the panels and prevent the collapse of the mine.

The size of the headings, pillars, and panels is determined by various factors such as the depth of the coal seam, the strength of the coal, and the stability of the surrounding rock. The size of the headings and pillars is calculated and designed to ensure the stability of the mine.

III. Size of Headings, Pillars, and Panels

A. Definition and Purpose of Headings, Pillars, and Panels

Headings: Headings are the tunnels that are excavated to access the coal seam. They provide entry and exit points for the miners and equipment.

Pillars: Pillars are the blocks of coal left behind to support the roof of the mine. They act as a barrier between the panels and prevent the collapse of the mine.

Panels: Panels are the smaller sections into which the headings are divided. They are created by leaving pillars of coal in between them.

B. Factors Affecting the Size of Headings, Pillars, and Panels

The size of the headings, pillars, and panels is determined by various factors such as:

1. Depth of the coal seam: The deeper the coal seam, the larger the size of the headings, pillars, and panels.
2. Strength of the coal: The strength of the coal determines the size of the pillars. Weaker coal requires larger pillars for support.
3. Stability of the surrounding rock: The stability of the surrounding rock affects the size of the headings, pillars, and panels. Unstable rock requires larger pillars for support.

C. Calculation and Design of Headings, Pillars, and Panels

The size of the headings, pillars, and panels is calculated and designed to ensure the stability of the mine. This is done through various engineering calculations and computer simulations. The design takes into account the factors mentioned above and aims to create a safe and efficient mining operation.

IV. Development of Panels

A. Definition and Purpose of Panels in Bord and Pillar Method

Panels are the smaller sections into which the headings are divided in the Bord and Pillar Method. They are created by leaving pillars of coal in between them. The purpose of panels is to facilitate the extraction of coal in a systematic and efficient manner.

B. Steps Involved in the Development of Panels

The development of panels in the Bord and Pillar Method involves the following steps:

1. Excavation of Headings: The headings are excavated to access the coal seam. This is done using various mining equipment and techniques.

2. Installation of Support Systems: Once the headings are excavated, support systems such as roof bolts, steel arches, and shotcrete are installed to ensure the stability of the mine.

3. Extraction of Coal from Panels: After the support systems are installed, the coal is extracted from the panels. This is done using mining equipment such as continuous miners and shuttle cars.

4. Monitoring and Maintenance of Panels: The panels are continuously monitored for any signs of instability or collapse. Regular maintenance and repairs are carried out to ensure the safety and efficiency of the mining operation.

V. Depillaring of Panels

A. Definition and Purpose of Depillaring in Bord and Pillar Method

Depillaring is the process of extracting the pillars of coal in the Bord and Pillar Method. It is done after the coal has been extracted from the panels. The purpose of depillaring is to maximize the recovery of coal from the mine.

B. Methods of Depillaring

There are two main methods of depillaring in the Bord and Pillar Method:

1. Full Extraction Method: In this method, all the pillars of coal are extracted after the coal has been extracted from the panels. This method allows for maximum recovery of coal but can lead to the collapse of the mine.

2. Partial Extraction Method: In this method, only some of the pillars of coal are extracted after the coal has been extracted from the panels. This method provides a balance between recovery and stability.

C. Challenges and Solutions in Depillaring

Depillaring poses several challenges in the Bord and Pillar Method. These include the risk of roof collapse, subsidence, and the release of methane gas. To overcome these challenges, various engineering techniques and safety measures are implemented. These include the use of roof support systems, ventilation systems, and gas monitoring systems.

VI. Real-World Applications and Examples

A. Case Studies of Bord and Pillar Method in Underground Coal Mining

There are numerous case studies of the Bord and Pillar Method being used in underground coal mining. These case studies demonstrate the effectiveness and efficiency of the method in extracting coal.

B. Comparison with Other Mining Methods

The Bord and Pillar Method is often compared with other mining methods such as longwall mining and room and pillar mining. Each method has its advantages and disadvantages, and the choice of method depends on various factors such as the depth of the coal seam, the thickness of the coal seam, and the geology of the area.

VII. Advantages and Disadvantages of Bord and Pillar Method

A. Advantages

• Efficient extraction of coal
• Provides support to the roof of the mine
• Allows for selective extraction of coal
• Suitable for mining coal deposits that are too deep for surface mining

B. Disadvantages

• Lower recovery of coal compared to other methods
• Risk of roof collapse and subsidence
• Requires extensive support systems

VIII. Conclusion

In conclusion, the Bord and Pillar Method is an important technique in underground coal mining. It allows for the efficient extraction of coal while ensuring the stability and safety of the mine. The method involves the creation of headings, pillars, and panels, and the size of these elements is determined by various factors. The development of panels involves the excavation of headings, installation of support systems, extraction of coal, and monitoring and maintenance. Depillaring is the process of extracting the pillars of coal, and there are two main methods: full extraction and partial extraction. The method has its advantages and disadvantages and is often compared with other mining methods. Overall, the Bord and Pillar Method is a valuable tool in the mining industry.

Summary

The Bord and Pillar Method is an underground mining technique used to extract coal. It involves the creation of headings, pillars, and panels, with the size of these elements determined by factors such as the depth of the coal seam and the strength of the coal. The development of panels includes excavation, installation of support systems, coal extraction, and monitoring. Depillaring is the process of extracting the pillars of coal, and there are two methods: full extraction and partial extraction. The method has advantages such as efficient extraction and support for the roof, but also disadvantages such as lower coal recovery and the need for extensive support systems.

Analogy

Imagine a chocolate bar with a grid-like pattern. The chocolate bar represents the coal seam, and the grid represents the headings, pillars, and panels created in the Bord and Pillar Method. The chocolate between the grid lines represents the coal that is extracted, while the chocolate within the grid lines represents the pillars of coal left behind for support. Just like the chocolate bar needs the grid to maintain its shape, the coal seam needs the headings, pillars, and panels to ensure the stability of the mine.