MANAGING Design for Mining

One area of mine management which offers significant opportunity to improve productivity and reduce costs is the design of the mining process.

Mine planners are normally responsible for this activity. Nevertheless there is ample opportunity for the production department to become involved as well, given their first-hand, detailed knowledge of how the process wor ks in reality.

The concepts behind the effective design of the mining process are often known in theory, but the principals are just as often not practiced. Underground oper ations usually offer more opportunity for mining process improvements than open pit operations, as the former process tends to be more complex, with more equipm ent handling smaller volumes over larger distances. The underground process is a lso largely hidden from easy view, and so inefficient practices are often permit ted to continue.

The main elements to be examined in designing the mining process are as follows:

* Type of Process — A mining operation (including the mill and other departments) can be viewed as a sequence of different processes. Three basic types of pr ocesses are possible: continuous-flow, batch and job-shop. Each of these types h as unique characteristics and unique requirements to function effectively. The t able below provides a brief overview of some of these requirements.

The first step in a proper analysis is to clearly understand the types of processes involved and the factors which are key to their efficient operation.

* Process Flow — Once the processes are introduced in general, the process flows should be looked at in a detailed manner. This involves examining the moveme nts and interactions of men, materials, ore and waste.

A diagram showing the process flow can be extremely helpful in identifying bottlenecks and streamlining activities. The diagram should show equipment production rates and inventories along the process stream.

With mining operations (as opposed to manufacturing operations), bottlenecks continually shift and can be elusive. However, an analysis of the process flow ca n provide a good idea of where the bottlenecks are.

* Information Flow — Information flow analysis requires tracing the movement of information needed to control the mining process. A schematic diagram showing the flow of information (via meetings, forms, letters, telephone calls, etcetera) helps one understand the information flow. This diagram should show who trans mits and receives the information, as well as the format and need for the inform ation. Such an analysis can often point to ineffective, and even risky, practice s. For example it may be found that most of the key information is handled by on e employee with no one else trained for the task.

* Long Range Planning — A mining operation can be analysed using project management techniques including critical path analysis. This kind of analysis become s very critical in an underground setting, where ore reserves must be extracted in sequence.

Reserves should be classified in terms of their sequence of extraction. For example reserves in crown and sill pillars should be classified separately if chut es or drifts lie within this ore.

A chart showing each classified ore reserve unit, the tonnage and production rate expected for each unit as well as the sequence of mining can be extremely us eful. Such a diagram would show where the critical path is, allowing action to b e taken to ensure adequate mining capacity in the future. Such action could cons ist of speeding up extraction in ore blocks which must be extracted early or dri ving new access drifts to bypass bottleneck areas.

Many mines don’t look far enough ahead and don’t plan, in a systematic way, the extraction of all existing ore reserves. Consequently these mines may have to eventually curtail production or write off ore reserves that create bottlenecks.

* Equipment Scheduling — A planned approach to equipment scheduling is necessary to avoid idle equipment and lost production. Preparing a schedule requires a clear understanding of:

— the work that is planned and the time frame involved;

— the detailed activities and sequencing involved;

— the productivity of each equipment unit required; and

— the availability of equipment.

The equipment schedule should be prepared in a simple format and posted. It will form a major input into the upcoming maintenance schedule. It will also provi de the guide for co-ordinating equipment and in communicating the need for sched ule changes to operating personnel.

All of these areas of process planning require regular and careful thought. Computer facilities have become a tremendous tool to assist process planning. Howe ver, good manual systems, specific to a company’s operation, must be developed p rior to implementing any computer system.

If effective manual systems are developed, the selection of appropriate computer hardware and software is easier. In addition, employees understand where info rmation comes from and how it is used rather than simply relying on a computer.

It is all too easy not to plan formally and, instead, to operate by the “seat of the pants.” Most large Canadian mines are good at process planning while smal ler smaller producers are weak in this important area. In the future, proper ana lysis and planning of the mining process will be essential for all mines in allo wing Canada’s mining industry to stay competitive. William Stanley is director of national mine services at Coopers & Lybrand Consulting Group.