Reliability applied to Secondary Fans in Mining

This article was written by Emerson Carlos Assunção Sanches, whose passing occurred on September 27, 2024. The publication of this work represents a posthumous tribute to a brilliant professional, mentor, and friend who contributed immensely to the success of FanTR from its inception.
A mechanical engineer and master in Mechatronics from UFBa, Emerson had extensive experience in Rotating Equipment Maintenance since 1978 and Reliability Engineering since 2009. Trained in Reliability Engineering at Reliasoft/Compass, he applied his expertise in major industries such as Cement Plants and Mining, and served as a professor at Cimatec, teaching undergraduate and graduate courses. His dedication and excellence have left a legacy that will continue to inspire professionals in the field.

1. INTRODUCTION

The secondary fans used in underground mines are fundamental elements in the operation and progress of underground mining. They are critical pieces of equipment and require continuous operational campaigns, without failures and delivering the required air flow and pressure.

This equipment is usually installed at the top of the gallery, making it difficult for the maintenance staff - mechanics, lubricators and predictive inspectors - to access it and carry out their work to keep the equipment running. (Figure 1)

Figure 1 - FanTR fan installed on the roof of the mine

Because of this difficulty, coupled with the maintenance strategy of some mines, this equipment is run to failure, and as a result, some components are damaged to a degree that cannot be recovered, causing longer downtime and high costs.

While other mines have taken the decision to carry out scheduled overhaul programs, Preventive Maintenance, removing equipment before it fails and replacing it with recovered and tested equipment. This policy reduces operational downtime and the cost of repairing removed equipment.

There are mines that have adopted mechanical condition monitoring of the fan and included an automatic lubrication system for the fan's electric motor bearings.

In these cases, the fan delivers greater availability, but at the same time is removed at the right time, avoiding further damage to its components, and with a replacement schedule adjusted to the operating condition. Repair costs and operational downtime are minimized.

This article, focused on Equipment and Systems Reliability, aims to help the operations and maintenance teams of mines that fall into the last two cases discussed in the previous paragraph and to motivate those that fall into the first case to review their current strategy.

 

2. THE SECONDARY FAN

      FanTR axial fans used in secondary ventilation in mining are generally made up of the following basic components, shown in Figure 2:

1. Rolling set:

• Electric motor;
• Central hub (fixed to the axle of the ME);
• Disc / ring (attached to the central hub);
• Fasteners, screws and nuts (central hub, disk and ring, split blades);
• Split bearings
• Aluminum split bearing (bearing type rotors);
• Shovel, made of fiberglass composite material, coated on the leading edge with stainless steel tape;
• Spinner (if available).

 

1. Static set:

• Metal housing;
• Noise attenuator;
• Fasteners, screws and nuts;

Figure 2 - Typical fan assembly