Ventilation friction factor determination and comparison: Two case studies of potash mining

Friction factor is a crucial parameter in assessing and modelling ventilation systems in underground mining. However, the development of a mine along its life-cycle can complicate the airflow supply required at the working faces, creating setbacks in terms of productivity and production. Hence, it is very important to determine all the ventilation parameters, including roughness and the friction factor. In this paper we examine the data from several surveys that were carried out in two potash mines (both using the room-and-pillar method) with the aim of determining the friction factors through the Von Karman equation, which connects the Atkinson friction factor with airway roughness. Comparison of the two mines provided consistent results, despite some differences in the mining methods, and we were able to establish standard values for this type of mining. Furthermore, a roughness variation over a year in this type of evaporitic mining has been determined, indicating that the specific climate characteristics of the zone affect the walls and roofs of the tunnels and therefore their roughness. Friction factor values have also been validated by means of several ventilation simulations and contrasted with values in the literature.