Top ten longwall problems

CONSULTANT Nick Wills takes a look at the top ten problems plaguing the longwall industry.

Angie Tomlinson

10. AFC Creep

Definition: The migration of the AFC towards the maingate or tailgate.

Causes: Direction of push, gradient, misalignment, poor face management.

Frequency: Quite common.

Risks to machinery: Mainly operational problems: binding of supports, broken equipment, loss of roof control, inability to cut out at ends.

Risks to people: Small.

Remedy: Training and good face management.

9. Excessive Water

Definition: Beyond normal requirements: mud, pools, free running water.

Causes: Leaking pipes and hoses, strata water, inefficient water sprays, broken pumps poor water management.

Frequency: Quite common.

Risks to machinery: Bogging of machinery, damage to electrical equipment.

Risks to people: Stumbling and slipping accidents, drowning.

Remedy: Training and good water management plan.

8. Horizon Control

Definition: “That which everything else must follow”

Causes: Operator error, lack of training, blunt picks, poor drum design, poor management.

Risks to machinery: Damage to AFC dog bones and drive frames, inability to advance AFC, potential for drum contacting support canopies.

Risks to people: Small.

Frequency: Common.

Remedy: Training, new technology (auto steering), cowls, good face management.

7. Dust

Definition: Particles of matter, the result of disintegration.

Causes: Blunt picks, transfer points, poor ventilation, poor suppression.

Risks to machinery: Small.

Risks to people: High risk through respirable dust.

Frequency: Respirable dust is well controlled but nuisance dust (particles you can see) are still common in most coal mines.

Remedy: Effective dust monitoring, well maintained equipment and effective dust suppression.

6. Attitude

Definition: Tendency to respond positively or negatively to an idea, object, person, which influences ability to succeed.

Causes: Interaction between people, management and workforce and invariably the other shift is always at fault.

Frequency: Common.

Remedy: Good team work.

5. Maintenance

Definition: Actions performed to retain an item in a specified condition, including periodic inspection, detection, condition monitoring, calibration, and critical item replacement to prevent incipient failures.

Causes of poor maintenance: Poor maintenance is directly related to poor management, lack of funds.

Risks to machinery: High.

Risks to people: High.

Remedy: Good face management.

4. Face Alignment

Definition: Whether a longwall is straight… or not.

Cause: Lack of training, poor face management.

Risks to machinery: High, damage to face chain, dog bones, trapping shoes, loss of strata control.

Risks to people: Low (except for loss of strata control).

Frequency: Very Common.

Remedy: Training and good face management.

3. Leg Pressures

Definition: The SET pressure in a support leg.

Causes of low set pressures: Lack of maintenance, defective equipment, poor equipment specification.

Risks to machinery: Potential for loss of strata control and subsequent roof falls.

Risks to people: High in roof falls.

Frequency: Very Common.

Remedy: Education, training, effective maintenance and good face management.

2. Face Training

Definition: Planned activities which support and improve individual and organizational performance and effectiveness.

Causes of poor training: Poor management.

Risks to machinery: High.

Risks to people: High.

Frequency: Very Common.

Remedy: Higher priority for good quality training programmes.

1. Stopping

Definition: The state of inactivity following an interruption. Statistically, roof falls are most likely to occur after a shutdown.

Causes: Coal clearance problems, planned shutdowns, unplanned shutdowns, poor maintenance, poor mine management.

Risks to machinery: High.

Risks to people: Low (except where a roof fall occurs).

Frequency: Very Common.

Remedy: Good longwall management. A longwall is at less risk if run “24/7”