Evaluating localised ventilation improvements on deep-level mines using simulation models

Abstract

The ventilation system of a mine is responsible for providing sufficient airflow in terms of quantity and quality. To ensure a safe and healthy environment, the main fans dilute and exhaust poisonous gases and dust throughout the mine. Due to the mine’s vast networks and depths, the ventilation system is challenging to manage and considerable time is spent investigating and identifying ventilation inefficiencies. The objectives of this study focused on developing a methodology that would identify ventilation problems on a localised ventilation network. The ventilation inefficiencies were mitigated through a simulation model. The localised network made it easier and less time-consuming to investigate, analyse and implement ventilation improvements. The methodology consisted of three phases, namely: Phase 1) identifying localised ventilation problems; Phase 2) building and verifying the simulation model; and Phase 3) implementing an optimised solution. At first, it was necessary to understand the mining network of the case study. In the case study, there were ventilation concerns regarding one particular level of the mine, which required further investigations. Key performance indicators and measurement locations were identified before a ventilation audit was conducted. These parameters and locations ensured that adequate data would be obtained for the baseline conditions and simulation model. After the ventilation audit, the data was analysed and restrictions, which largely influenced the airflow measurements, were noted. Assumptions were made to establish the final actual baseline conditions. From the actual baseline conditions, inefficiencies such as high temperatures and low to no airflow were recorded at the workshop area of the affected level. A simulation model was built in Process Toolbox 3D using all the information and data obtained. A discrepancy of 4% occurred between the simulation model and actual baseline conditions after verification and calibration. Three scenarios were simulated during which the ventilation inefficiencies of the level were mitigated and different ventilation plans were introduced to improve the conditions. After simulation, Scenario 3 was selected as the most feasible solution, which was implemented with no additional electricity costs added to the ventilation system. The scenario was validated by repeating the audit on the level. During the audit, the conditions proposed by Scenario 3 differed from the actual conditions due to a constructed wall leaking air and a fan being switched off. As a result, the validation of the air mass flow had a defect of 22.64%. The simulation model was adjusted through mass balancing to align with the conditions recorded during the audit. Subsequently, a defect of 0.08% was achieved for the average air mass flow through the workshop area. The actual average air mass flow recorded through the workshop area increased with 21.47 kg/s. The temperature recorded had a defect of 1.01% and 1.83% for the wet-bulb and dry-bulb temperatures, respectively. The actual average wet-bulb temperature over the workshop area decreased with 1.16℃. Thus, the overall percentage error determined for the entire system between the simulation model and actual results was 0.98%, which indicates the accuracy of the simulation model. Thus, all the objectives for this study were met.