Ayrshire Mine Celebrates 4 Hour Re-entry Success with Zero Gas Incidents
In a significant achievement for safety and operational efficiency, Ayrshire Mine has successfully implemented a 4-hour re-entry protocol in its ventilation system.
By Ryan Chigoche
In mine ventilation, the term “4-hour re-entry” is crucial not only after incidents such as fires or explosions but also following blasting operations. After a blast, a mandatory waiting period of four hours is enforced before personnel can safely re-enter the area.
This waiting period allows for the dissipation of harmful gases, including nitrogen oxides and other byproducts released during blasting. It also provides time for the environment to stabilize, enabling any potential secondary hazards, such as rock falls, to become evident.
During this period, ventilation systems are assessed and adjusted to ensure safe air quality for re-entry. Additionally, monitoring vibrations is essential, as the ground may remain unstable immediately after a blast. Overall, the 4-hour re-entry rule is a vital safety protocol in mining operations, protecting workers from the risks associated with blasting and other hazardous events.
Since implementing the 4-hour re-entry guideline, Ayrshire Mine has reported zero incidents related to harmful gases. This remarkable achievement highlights the effectiveness of the ventilation system, which dissipates toxic gases and maintains a safe atmosphere for workers. Proactive measures taken by the team have significantly reduced risks, contributing to a safer workplace.
Maintaining optimal air quality is critical in mining operations, and Ayrshire Mine consistently monitors environmental conditions to achieve a wet bulb temperature (WBT) of 24°C and a dry bulb temperature (DBT) of 29°C. These controlled conditions are essential for ensuring a safe and productive working environment.
This focus on maintaining optimal air quality allows personnel to work for 8 hours or more without experiencing heat stress. The commitment to employee health not only enhances productivity but also fosters a culture of safety and well-being among the workforce.
The Ayrshire Mine team remains dedicated to continuous improvement, exploring further enhancements in ventilation technology and safety protocols. The mine aims to uphold high safety standards while optimizing production processes.
With these milestones, Ayrshire Mine sets a benchmark for best practices in the industry, demonstrating that a commitment to safety and operational efficiency go hand in hand.
Ayrshire Mine Ventilation System Overview
Intake Airway
Ayrshire Mine’s ventilation system utilizes fresh air drawn downcast through Open Pit 1, located east of the Edward Shaft. The airflow follows this path:
- Entry: Air enters through Open Pit 1.
- Descent to Level 13: Air descends via raises and stopes.
- Circulation to Levels 14 and 15: Air circulates through:
- 13 West 124 Winze
- Other connecting levels
- Circulation to Levels 16 and 17: Air moves through the 13 West 67 drive sub-vertical shaft.
Return Airway
The return airway is essential for maintaining air quality:
- Foul air is upcast from Level 17 to Level 13 via the sub-vertical shaft.
- It continues from Level 13 to Level 12 through the 13W 412 Tway.
- From Level 12, foul air is upcast into box raises, Tways, and stoppings, eventually reaching the Susan Maria and 366 main fan.
Current Ventilation System
The current airflow rate in the drives at Ayrshire Mine is 3.5 cubic meters per second. The mine employs a hybrid ventilation system that effectively combines natural ventilation with mechanical assistance. This includes one operational exhaust auxiliary fan that supports underground operations, drawing an impressive 9.8 cubic meters per second, ensuring that fresh air is consistently circulated throughout the mine.
Air Quality and Monitoring
Maintaining air quality is a top priority at Ayrshire Mine, and this is rigorously monitored to safeguard the health of personnel. At the 4-hour re-entry, the mine has recorded zero harmful gases, demonstrating the effectiveness of its ventilation strategies. Additionally, dust levels are currently measured at 2 mg/m³ in underground areas, indicating a controlled and safe working environment.
Ventilation Challenges
Despite these efforts, the ventilation system faces several challenges. Blocked return airways can force foul air to divert to the shaft, compromising air quality. Furthermore, unrepaired ventilation doors hinder proper airflow, and inconsistent door closure practices by personnel add to the problem. Damage to ventilation walls and an unoptimized return airway configuration also contribute to inefficiencies within the system.
Improvements and Solutions
To address these challenges and enhance the ventilation system, several improvements have been proposed:
- Installing a 75 kW surface fan to boost airflow.
- Adding an exhaust fan underground at a dead end to improve circulation.
- Implementing ventilation ducts to facilitate efficient movement of foul air.
- Repairing existing ventilation doors and constructing new ducts to strengthen overall system effectiveness.
The hybrid ventilation system at Ayrshire Mine, which combines natural and mechanical ventilation, has undergone recent upgrades to further enhance its effectiveness. Key improvements include the installation of surface ventilation at underground dead ends and the implementation of ventilation ducts designed for the efficient removal of foul air. These enhancements have improved airflow and increased safety for personnel, resulting in better health and productivity among miners. Additionally, these upgrades ensure compliance with regulatory standards, reinforcing Ayrshire Mine’s commitment to safety.