There are tens of thousands of inactive mine features in 274 mining districts in New Mexico (including coal, uranium, metals, and industrial minerals districts). However, many of these mines have not been inventoried or prioritized for reclamation or reprocessing. Many of these mines have existing mine wastes, generated during mineral production, which could have potential for critical minerals, especially since the actual mineral production was generally for precious and base metals and not critical minerals. The purpose of this project is to inventory, characterize and estimate the critical mineral endowment of mine wastes using USGS sampling procedures. This project is important to the state of New Mexico because critical mineral resources must be identified before land exchanges, withdrawals or other land use decisions are made by government officials. Future mining of mine wastes that potentially contain critical minerals will directly benefit the economy of New Mexico. Possible re-mining and/or reprocessing of mine wastes could clean up these sites and pay for reclamation. Furthermore, this project will include training of younger, professional geologists and students in economic and reclamation geology by the PIs.
In 2013, a team of New Mexico Tech researchers began a study of uranium transport, uranium source characteristics, and uranium legacy issues in New Mexico. The effort was funded by Energize New Mexico, a five-year NSF EPSCoR program that concluded in 2018 and that encompassed five research components focused on developing non-carbon emitting energy technologies. The uranium team, which included researchers from UNM, addressed uranium deposits and mine waste mainly in the Grants Mining District, including Laguna Pueblo, and on Navajo Nation lands. These uranium studies span a range of science and engineering disciplines, and not only provide new conclusions impacting remediation, hazard management, and uranium extraction, but hold implications for human health.
Although no uranium mines are operating in New Mexico today, the legacy of the mining industry requires continuing evaluation and remediation of inactive or abandoned mine features, which number around 300 for the uranium industry alone. The sites of mining activities can offer physical and chemical threats to individuals, communities and the environment. Dr. Virginia McLemore has assembled a team of New Mexico Tech students to evaluate mine sites throughout New Mexico as part of the Abandoned Mine Lands Project.
Many metals can be harmful to humans when they are taken into the body. We often think of drinking water when we think of these sources, however, toxic metals can also be taken into the body as inhaled particles or as part of our food. In this study, dust particles were mixed with one of two simulated lung fluids in an airtight glass reactor (configured as the figure to the right) where the solution was heated to a constant temperature of the standard human body temperatures – 37?C (98.6 ?F) – in a vessel purged with oxygen just before adding the dust sample. The study found that the uranum in some dust samples (and lab standards) dissolved better in one or the other of the fluids and that this phenomenon seemed to be based on the mineralogy and available surface area of the dust and the pH of the fluid.
Microbes can play an important role in geology and in the precipitation and dissolution of mineral components. Uranium is most commonly mobile in the environment with a charge of 6+, referred to as oxidized uranium, usually forming the uranyl molecule, UO22+. It is most commonly precipitated with the oxidation state of 4+, referred to as reduced uranium, to form minerals as the molecule U3O8. Microbes, which are constantly seeking metals and molecules that they can use as nutrients, energy sources, and electron acceptors, often reduce such metal species (changing uranium 6+ as UO22+ to uranium 4+ as U3O8, for example) as part of their metabolic processes; however, not all microbes reduce all metal species. Identifying microbes that can reduce the uranyl molecule and therefore create an environment ripe for uranium precipitation could be important for understanding how uranium deposits occur and for identifying possible tools for uranium mine remediation.
Understanding the relationship of dust to uranium contamination can be critical to predicting if and how uranium moves by dust from a mine site, as well as predicting if the health of nearby community members and mine workers can be affected by mining activities. In this study, dust traps were installed at several locations at Jackpile Mine, a remediated uranium mine site at Laguna Pueblo, New Mexico, to evaluate this problem. In all samples, uranium levels were low, however, they were statistically high enough to help researchers determine dust influences on the movement of uranium.
