A process for evaluating different options for extraction of mining blocks is presented. The process is described and an example of the application of the process to a case study is presented.

Un procede pour evaluer differentes options pour l'extraction de blocs d'exploitation est presente. Le procede est decrit et un exemple de l'application du procede à un cas particulier est presente.

Ein Prozeß fuer das Auswerten der unterschiedlichen Optionen fuer die Extraktion von Abbaublöcken wird dargestellt. Der Prozeß wird beschrieben und ein Beispiel der Anwendung des Prozesses zu einer Fallstudie wird dargestellt.


A design process, "Optimine", to evaluate risks associated with the extraction of mining blocks is presented. It is discussed in terms of its application in evaluating the pre-determined risks associated with extraction of an above normal risk remnant at a depth of approximately 3000 m on the Carbon Leader Reef.

"Optimine" Process

The "Optimine" design process that is followed to optimise mining layouts and sequence from a rock engineering perspective is presented in Figure 1a.

(Figure in full paper)

Figure 1a. "Optimine" design process to evaluate optimum mining layouts and sequence. The process is divided into three phases, pre-mining, mining and the post-mining phase. More detail of the pre-mining phase of the "Optimine" process as applied to a case study is given in Figure 1b.

(Figure in full paper)

Figure 1b. Further detail of the pre-mining phase of the "Optimine" process.

The first step in the process is to define the scope and objectives. This refers to the extent of the mining area to be evaluated, etc. The next step is to list all options and to evaluate these options based on sound rock engineering principles. From the evaluation results, the preferred options are identified and selected. A broad quantification of the risk associated with each of these options is then conducted in terms of an underground observations, seismic analysis, empirical tools and local knowledge, which will feed into a numerical analysis, which is conducted on a purely comparative basis. These options are then ranked in terms of the risk associated with each option. The best option can then be chosen and implemented together with a continuous risk assessment programme. A brief explanation on how the underground observations, empirical rules, seismic analysis and numerical modelling can be applied in the design process follows.

Underground Observations

Investigation of the service and stoping excavations can give an indication of the principal stress directions, rock types, support conditions, etc. which can feed into a risk assessment.

Empirical Rules

Empirical rules are useful when evaluating different mining sequences e.g. accepted rock engineering practice suggests mining away from seismically active structures or approaching geological structures at an angle of greater than 30°. Thus, before the numerical analysis is even conducted, an idea of the mining layout and sequence can be obtained by applying basic rock engineering principles.

Seismic analysis

A record of seismic data catalogues must be made available for the analysis.

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