Controlling dust concentration in a fan housing using settling chambers and water sprays

Abstract

Dust generation is a consequence of various activities in the mining industry. The industry generates dust in quantities that can present occupational health hazard and equipment damage. A notable instance of equipment deterioration is the corrosion and erosion experienced by fan blades in underground mines. This thesis introduces settling chambers and water spray as feasible techniques commonly used for controlling dust in underground mine operations. The research aims to provide a low capital cost and maintenance-free system to capture the dust particles upwind of the main fan. The research focuses on an underground polymetallic mine in Peru, serving as a case study. It was conducted in two distinct phases. In the first phase, airflow data in the upcast shaft and the fan housing was collected from the collaborating mine in Peru. Subsequently, a 3D model of the shaft and the fan housing system was developed, and a Computational Fluid Dynamics (CFD) simulation of the airflow in the system was performed. The results of the CFD simulation were compared against the airflow data from the mine, and the CFD model was validated. The 3D model of the upcast shaft-fan housing system was adapted to incorporate the settling chamber, which underwent variations in shape, length, and hydraulic diameter, resulting in the creation of 18 modified models. For each model, CFD simulation was conducted in steady-state condition to establish flow in the computational domain, followed by transient-state simulations to replicate the behavior of dust and assess the settling chamber's efficiency in capturing dust particles with aerodynamic diameter ranging from 1 μm to 400 μm. Furthermore, Sensitivity analysis was performed to examine the effect of shape, length, hydraulic diameter, and airflow velocity on the capture efficiency of the settling chamber. Analysis of the simulation results indicated a significant dust reduction of up to 60%. The second phase of the research involved simulated the capture of dust using water spray system within a return entry. Different water spray nozzles, characterized by varying spray angles, velocities, and droplet sizes, were simulated to evaluate their impact on dust capture efficiency. The analysis of the results revealed that the system could achieve a dust capture efficiency of up to 60%.