Mining Project: CFD Modeling in Processing Facilities

Research Summary

During mineral processing of ore, a large amount of dust is generated which creates hazardous conditions for workers at the mineral processing plant. Many mineral processing plants have difficulty meeting the federal standards for respirable dust. Engineering controls address the most significant dust sources; however, less significant and minor dust sources such as leakage from chutes, transfer points, and conveyor belts are often not properly addressed. These dust sources can cause serious health effects over a prolonged period of time, especially when the ore being milled has a high silica content. Therefore, it important to study various factors affecting the transport of dust in mill buildings and to design a ventilation and control system that will keep the dust levels within permissible limits.

Evaluation of dust exposure can be done by sampling; however, the dust sample collected will only reveal exposure at a fixed location at that time. Thus, it is required to assess the transport of dust throughout the entire mineral processing facility in order to reduce worker exposure. Dust generated does not stay near the source but is transported to different locations due to both active and passive (natural) ventilation, wind, solar heating, and other factors.

To address these issues under this pilot project research, preliminary computational fluid dynamics (CFD) models were developed to study the flow behavior and other factors affecting the dust generation and transport at one particular mineral processing facility. The intent of the pilot project was to identify the dust generation sources and modes of transport using the CFD models, and then to devlop a total mill ventilation system (TMVS) model. The developed model for a TMVS would then be implemented at a partner mine or mines to assess its effectiveness.

The overall project was designed to be carried out in two phases:

Phase 1. A proof of concept was done within the one-year pilot project. The tasks under this phase included finding a collaborator, conducting a field survey to collect data that reflects current ventilation, dust sources, and airborne dust levels in a mill, and using the data to develop a CFD model for assessing the control of dust concentrations via ventilation modifications in the mill. This phase of the project was completed, and the results were published at the 2018 SME Annual Conference & Expo.

Phase 2. The tasks under this second phase were to develop a TMVS based on the CFD model developed in Phase 1, present the most promising results from the TMVS models to collaborator stakeholders, and implement the TMVS design at the collaborating mine’s mineral processing facility. After establishing CFD as a viable tool for designing and modeling mineral processing facilities, we intended to use this approach to design an automated mill ventilation system. This phase of the work was not completed due to changes in research funding..

Ultimately, this project was designed to help researchers to understand the flow behavior of dusts in a mineral processing plant on a day-to-day basis as well as seasonally. The intent was to use that information to help in proposing a better ventilation design, which will finally lead to improved health and safety and working conditions for mill workers.