Scheduling

Scheduling may be defined as the allocation of available resources to activities over time, in a manner such that corporate objectives are met. There is however no universal scheduling method that covers all situations. A scheduling method used at one mine may not necessarily satisfy the requirements of another mine, for reasons that are both tangible and intangible.

The economic feasibility of a mine is usually based on a block model that defines the tonnes and grade of the ore body.  These ore blocks typically have a regular size.

The fundamental component of the mining (or extraction) process is a mining block. The design of mining blocks is dependent on a number of physical parameters, including the mining method and the type of equipment to be used. The blocks in a mining model need not be regular in shape or size, and will have associated attributes, such as tonnes and grade. Mining blocks are a three-dimensional representation of the material to be removed, and form the basis of the subsequent production sequencing.

A mine schedule, in simple terms, defines when and how each mining block will be extracted. Scheduling deals with the allocation of resources to tasks over time, in such a way that some constraints are satisfied and some goals are met. The constraints may regard both the tasks and the resources.

Many mining operations use a manual scheduling process. It is not uncommon to combine generic spreadsheet and project management applications to accomplish this. Although these tools have the capability of getting the job done, there are problems:

• The formulae and equations that control the spreadsheet calculations can become quite complex and difficult to maintain. This is particularly so if the original author moves on.
• The definition of mining blocks, and their associated attributes, is invariably done in some other application. Getting this information into a spreadsheet, and updating it when necessary, can be clumsy and error prone.
• Other than by exporting to an appropriate application, there is no way to visualise, or animate, the schedule in 3D. This introduces a degree of risk
• The Gantt chart facilities provided by applications such as Microsoft Project®, enable a diagrammatic representation of the schedule. However they lack the ability to handle mining attributes such as tonnes, grades and equipment resources.

The Micromine Scheduler module provides a neat, integrated solution. Mining block solids (wireframes) are created using the purpose-built tools in Micromine. Block model attributes are assigned to the mining blocks.

One of the requirements of the mining model is to generate a mine plan which represents the tonnes and grade (quality) in both a graphic and a tabular form. Scheduling involves defining the mine layout as a series of mining blocks, sequencing the order in which those blocks will be mined, and mapping this to a timeframe in order to meet periodic targets.

The Scheduler has provision for sequencing and the allocation of resources to the mining blocks. With a time component added, the mining blocks can be visualised in Vizex (MICROMINE’s 3D environment), in a Gantt Chart window, or as a report. The import and export of information to and from a third-party package is now redundant.

For more information, refer to the Mining Planner.