Since 2023, Barr Engineering Co. has been providing engineering and environmental services to Nevada Gold Mines (NGM).
NGM hired Barr to study air emissions from three facilities: the roaster at the Gold Quarry mine and the roaster and autoclave at the Goldstrike mine. The company wanted to understand whether increasing throughput at the three facilities would jeopardize compliance with the limits specified in their air permits. The goal of the study was to determine how expanded operations might affect compliance with air emission limits at facilities that use performance testing or continuous emission-monitoring systems (CEMS) to measure emissions.
Barr took a five-step approach to completing the evaluation:
- Summarized baseline emissions from five years’ worth of performance-test data and CEMS data, where applicable.
- Created a preliminary estimate of future emissions by employing descriptive statistics and projected future operating rates.
- Assessed the risk of emissions exceeding permit limits at each source to determine where additional analysis was warranted.
- To recommend the most promising strategies for lowering the risk of exceedances, developed multiple linear-regression models for further studying the impact of future operating rates on emissions; better assessing the compliance risk for emission sources flagged in step 3; and evaluating the degree to which modifying processes might maintain or reduce emissions.
- Identify potential actions such as combustion tuning, process optimization, process modifications, and emissions testing campaigns that could minimize the potential for exceeding permitted emission limits.