A model for prediction of unplanned dilution in underground metal mines considering rock engineering systems

The over-break and slough of walls and roof of stopes in underground mines leads to unplanned dilution and dropping in the grade. The complex mechanism of unplanned dilution resulting from the effect of different parameters and interaction between them makes it impossible to provide an unplanned dilution model with sufficient accuracy through non-system methods. In this paper, a high-precision model in which interactions between parameters are considered is presented using the rock engineering systems approach. For this purpose, after selecting 8 parameters, as the most important parameters for unplanned dilution, the steps of this method include the formation of interaction matrix, matrix coding and formation of the ranking table, the index of unplanned dilution of 24 stopes from the Venarch Manganese mines has been calculated. Subsequently, using the cavity monitoring system, the actual values of unplanned dilution of each stope were measured and from there the unplanned dilution prediction model was obtained based on the unplanned dilution index. The model, which is a power relationship, has a coefficient of 0.89, root mean square error of 0.034, mean absolute error of 0.089 and a percentage of variance of 87. In the end, using this model, unplanned dilution of 9 new stopes (other than the 24 workshops) was predicted and compared with the actual values measured. The coefficient of this prediction is equal to 0.95, which indicates the high efficiency of the model and system approach in predicting the unplanned dilution of underground mining stopes.