Investigation of respirable mine dust and crystalline silica dust characteristics and toxicity in nonmetal mines
Restricted (Penn State Only)
- Author:
- Sharmba, Tsunami
- Area of Honors:
- Environmental Systems Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Mohammad Rezaee, Thesis Supervisor
Jeremy Michael Gernand, Thesis Honors Advisor - Keywords:
- mine dust
mining
crystalline silica
respirable dust
respirable
metal
nonmetal
bioavailability - Abstract:
- Recent NIOSH-funded research activities on respirable coal mine dust have provided essential insights into the root causes of lung diseases among coal miners and sampling techniques and real-time measurements. Several researchers have focused on characterizing coal dust and silica dust in surface and underground coal mines. However, less attention has been given to respirable dust and respirable crystalline silica (RCS) in metal and nonmetal (MNM) mines. Therefore, physicochemical qualities and toxicity of mine dusts remain poorly understood. Detailed investigation of dust particle characteristics and toxicity will lead to an improved understanding of factors related to health impact, silica monitoring, and dust control techniques. To addresses this critical gap-in-knowledge and the 2019-2023 NIOSH Strategic Plan for mining "to eliminate mining fatalities, injuries, and illnesses through relevant research", this research conducted comprehensive characterization of non-metal respirable mine dust and crystalline silica. Bulk and respirable dust samples were collected. Respirable dust sampling was performed using Escort Elf pumps with nylon 10mm Dorr-Oliver cyclones and operating at 1.7 L/min sampling flow rate (adopted from dust sampling in coal mines per 30 CFR part 70), with 37 mm diameter cassettes. The sampling was conducted in vicinity of various operations to represent their contribution to mine dust concentration/characterization. The respirable dust samples were then characterized in detail for size and mineralogy distribution, crystalline silica analysis, elemental content, bioavailability and hydroxyl radical analysis. The results showed that submicron particles, which accounted for 50-74% of the total particle numbers across all sampled mines, were prevalent. Despite their minimal contribution to the overall mass, these particles pose a greater risk due to their potential for deeper respiratory penetration. Mineralogical analysis revealed significant differences in dust composition among mining sites, with calcite and dolomite dominating in certain samples (e.g., TV mine) and silica-rich compositions (10-18% quartz) in others, consistent with local geological formations. Elemental bioavailability analysis indicated high levels of bioaccessible elements, including thallium, boron, scandium, nickel, and lanthanum, which could heighten toxicological risks for workers exposed to respirable dust. Hydroxyl radical testing demonstrated an enhanced oxidative potential in simulated lung fluid, with some samples generating significantly more radicals than in deionized water, underscoring the increased reactive potential of dust in lung-like conditions. This study provides critical insights into the physicochemical characteristics and potential health risks of respirable dust in non-metal mines, contributing valuable data to improve safety standards and dust management practices in the mining industry.