Understanding Water Chemistry Under Uranium Recovery by In Situ Leaching for Aquifer Restoration

Tuesday, February 23, 2016: 1:10 p.m.
Omar Ruiz , Civil Engineering, University of New Mexico, Albuquerque, NM
Bruce Thomson, Ph.D. , Dept. of Civil Engineering, University of New Mexico, Albuquerque, NM
Jose Cerrato , Civil Engineering, University of New Mexico, Albuquerque, NM

From 1950 to the early 1980s, New Mexico played an important role in the production of uranium (U) for the nuclear power industry and the nation’s weapon programs. Though the U mining and milling industry is largely dormant at present, increased interest in nuclear power as a CO2 free power source has led to proposals for renewed development of U resources. In particular, U mining projects have been proposed using both underground mining and in situ leach (ISL) mining. The objective of this presentation is to investigate remediation methods that could possibly be implemented in New Mexico after ISL of U mining. In principle, ISL mining will minimize waste by eliminating mill tailings, mine waste rock, mine dewatering, and radiation exposure. ISL mining has not avoided environmental impacts and therefore an evaluation of complexation and redox reactions affecting the interactions between U minerals and co-constituents, which may include but are not limited to arsenic, chromium, molybdenum, selenium and, vanadium. Batch experiments of low-grade ore were conducted and show that U and co-constituents are dissolved and therefore need to be considered for aquifer remediation. Leach tests have been performed with acids to determine the total metal concentrations; NaHCO3 lixiviant was used to understand U and metal dissolution. Results from batch experiments have allowed an understanding of the effectiveness of ISL mining, and the potential impacts on groundwater quality. Remediation process will be composed of in-situ approaches that might include clean water flushing, DO depletion, chemical/bacteria reduction, and evaluating organic matter for positive or negative impacts on remediation. Abundant resources that are found through leaching experiments will be considered for remediation purposes. These results will be presented. These results will explain what processes could be potentially effective for aquifer restoration after ISL of U in New Mexico.

Omar Ruiz, Civil Engineering, University of New Mexico, Albuquerque, NM
Omar Ruiz is currently obtaining an M.S.C.E. with a focus in environmental. His work consists of researching advanced in-situ recovery of uranium and remediation of subsurface water after ISR. Not only will he be working with the source of nuclear energy but will also have the opportunity to try to remediate groundwater and help people that live around ISR mines.

Bruce Thomson, Ph.D., Dept. of Civil Engineering, University of New Mexico, Albuquerque, NM
Bruce Thomson is Director of the Water Resources Program and Professor of Civil Engineering at the University of New Mexico. His research interests focus on water chemistry and treatment. He has a Ph.D. from Rice University in Environmental Science and Engineering.

Jose Cerrato, Civil Engineering, University of New Mexico, Albuquerque, NM
Jose Cerrato’s research interest is related to biogeochemical processes at the interface of water and energy that affect the cycle of metals and radionuclides in the environment. He leads the E-H2O Research Group which applies spectroscopy, microscopy, aqueous chemistry, and molecular biology tools for the study of complex environmental interactions.