Reliable lubrication can have a direct impact on operational efficiency by lengthening machine life and decreasing maintenance costs. Maurice Jones reports
Modern mining equipment lubrication has to keep up with the demands now placed on the equipment itself, and this usually means allowing the equipment to operate faster and handling greater loads.
In addition to these requirements directly related to production, pressures for better environmental care may affect the choice, whether out of good practice or to meet regulations. The main hazards to be avoided are usually contaminating of aquifers such as by accidental spillages, and possible harm to lubricant users such as through skin contact.
Although central lubrication systems have the advantage of labour saving, and the days of the ‘grease monkey’ and multiple manual lubrication points are long gone, the lubrication demands of each part of mining equipment can vary greatly. Thus, as indicated by the equipment manufacturer, the lubricant used must meet the required specification to achieve the demands of each component requirement for lubrication. This may mean using a specialist lubricant or an oil of grease that can cover a wide range of duties, and various lubricants for each duty on the same piece of equipment.
The industry is offered general and specialist lubricants to meet these requirements by both multinational oil giants and more specialist producers working on a national or regional basis. Specialist lubricants often contain additives to the basic petroleum (natural or synthetic) product to enhance various properties such as increased viscosity, tackiness, friction reduction, increased life at extreme temperatures and better wear protection.
In addition to selling lubricants some suppliers, like Lubrication Engineers (LE) of Kansas, USA, offer consultancy in lubricant performance through protection against ingress of water and other contamination. LE uses a network on consultants to develop tailored programmes for each mining operation.
As one of the multinationals serving the mining industry Shell offers a broad range of speciality lubrication products and services including heavy-duty diesel engine oils, gear oils, axle and transmission oils, greases, and hydraulic fluids. Shell offers various services to aid selection of the right lubricants including a recently introduced data centre to enable easy downloading of product information. In addition a wide variety of mining case histories are available. Shell emphasises the relatively low cost of good lubrication compared to the overall cost of maintenance within the total cost of ownership of any item of plant.
The requirements placed on a lubricant may include:
* Range of operating temperatures;
* Ambient temperature including special lubricants for polar, tropical or deep underground mine conditions;
* Viscosity and stability of viscosity;
* Frequency of lubricant change c/w normal planned maintenance;
* Minimal hazard to health and environment;
* Cost.
Hydraulic systems require a fluid of long life that can both transmit pressures reliably and rapidly as well as lubricating the moving parts that it comes in contact with, such as pumps, motors and rams. In coal mining and work in other hazardous atmospheres the hydraulic fluid may be a special mix of lubricant and water to avoid a possible fire hazard.
The main practices adopted for frequent mining plant lubrication are either working from a mobile lubrication wagon and/or a central (grease) lubrication system on board the unit featuring a pump feeding bearings and other lubrication points with suitable grease.
Video 1: Lincoln Industrial, part of the SKF bearing engineering group, offers automatic lubrication systems for construction and extraction plant with benefits explained here
Video 2: Lubrication truck by Sage Oil Vac of Australia featuring a patented vacuum and pressure process for lubricant transfer
