Assessments of Boundary Conditions and Requirements for Rare Earth Underground Mining Due to Presence of NORMs

Rare Earth Deposits & Mining / Rare Earth Exploration, Mining, Processing, & Uses

Barakos, and 2 co-authors reported in 2014 rare earths contain naturally occurring radioactive materials  (aka NORMs), such as uranium, thorium and their progeny, like radium and radon. The varying concentrations of NORMs are quite often significant enough to result in occupational and environmental radiation exposures during the mining, milling and processing procedures of rare earths and compounds. Ventilation is the primary technique of controlling ambient concentrations of radon. Fresh air volume flow rates, the distribution of airflow within the mine and the radon emanation rate are primary factors affecting such concentrations. The authors attempted to determine the factors that may result in radiation risks and evaluate the boundary conditions that will contribute to the restriction or even elimination of radon progeny, with a goal to use the evaluations in order to build an overall assessment tool. 

The presence of NORMs, especially of radon, is a paramount safety and health issue for the underground mining industry. This poses challenges for ventilation engineers to minimize the radiation contamination of the air and thus the human exposure. The most efficient methods to achieve control are; mechanical dilution ventilation, confinement or suspension of radiation source, dust reduction and control as well as personal protection measures. The improvements made so far have reduced radon concentration in underground mines, however, the work to further improve the evaluations continues. In an ideal underground rare earth mine radon accumulation is prevented and radiation concentration is kept to very low levels with respect to safety and cost efficiency. For this reason, a comprehensive investigation was made by the authors to evaluate the primary boundary conditions and requirements. These evaluations should be useful in order to build an overall assessment tool, to adjust and to apply special techniques in mining of radon‐emitting deposits.

[One of principal contributing factors in lung cancer occurrences was smoking by the underground mine workers (who inhaled)while smoking) during the 1950s and 1960s. Combined with a lack of ventilation, the workers were seriously exposed during those days. Today, this has been eliminated via improved ventilation and "no smoking" while underground mining rules in the mines. For more see (more)]