Maintenance procedures can also be hazardous in their own right. Maurice Jones highlights the dangers
It is widely recognised in all well-run mines that for working equipment to breakdown is not only bad for sustained production but it is bad for safety too. Hence the concept of planned preventative maintenance came about. However, the act of maintenance has many of its own hazards that maintenance practitioners and their assistants should be aware of.
Awareness of possible hazards is just one reason why those engaged in maintenance must be trained to the appropriate level. For more complicated equipment such as electrical apparatus and gearboxes, this will include formal qualification. The necessary training will include tuition in safety hazards to both the artisan and others, and there are many hazards to consider. Just some of those known to cause death and serious injury are:
1. Starting machinery when somebody is working on it, including when changing bits and picks;
2. Switching on power when somebody is working inside electrical equipment;
3. Loss of hydraulic safety valves allowing collapse of heavy equipment such as roadheader booms;
4. Inadequate plant support when working beneath;
5. Use of parts and consumables with incorrect specifications;
6. Inadequate attention to maintaining explosion-proof properties of equipment in coal mines and similar hazardous atmospheres;
7. Runaways of wheeled equipment;
8. No provision for handling heavy parts,
9. Tripping and stumbling over untidy working areas.
Many of these circumstances can be avoided by good working practice, put some necessitate other provisions. For example interlock safety switches and warning signs can prevent a plant operator or other third party from starting equipment that is being worked on. Also adequate support, braking and chocking can prevent unexpected movements rather than rely on possibly compromised equipment systems.
While a lot of maintenance, especially for breakdowns, may have to be carried out at the place of use, or nearby, the provision of a clean, well lit, and well equipped working environment will go a low way to ensuring maintenance is carried out safely. Many enlightened mine operators, especially of large mines, provide maintenance workshops near to the sector of use. This is particularly important in underground mines as a long trip to the surface for ordinary maintenance is a deterrent to good practice. Some also provide smaller lubrication bays for frequent maintenance.
For work in open pit mines same tasks may have to be carried out in open areas requiring the provision of suitable mobile lifting equipment such as a rough-terrain forklift or crane to lift wheels, tyres, etc.
Sometimes, particularly with sealed systems, it may have been considered best to ‘leave well alone’ rather than indulge in preventative maintenance that may open a system to contamination in the harsh environment of mining. However this still leaves open the possibility of unexpected breakdown and consequent loss of equipment availability. Equipment condition monitoring should remove this concern with regular analysis of lubricants and hydraulic fluid, plus sensors at strategic positions, such as on bearings, for vibration, temperature, and flammable gases.
Some major manufacturers have extended the concept to providing regular reports to the mine operator, and perhaps the manufacturers also, to warn of deteriorating machine conditions. A further development is to provide these reports, including limit warnings, in real time to remote locations so that Possible breakdown warnings can be instant. Another maintenance aid innovation in modern equipment is to design it with better access to maintenance points. Those requiring regular attention such as filters, dipsticks and filling points are, wherever possible, grouped together in one location accessible from ground level, hopefully eliminating the need to climb over equipment.
Videos: Part of a series, this Florida Mine Safety Training video funded through the US Mine Health & Safety Administration (MHSA) features safety in maintenance operations
