The Environmental Legacy of Mining & Milling in New Mexico Bruce Thomson Civil, Construction & Environmental Engineering University of New Mexico ([email protected]) Fiestaware Early Uses & Source of U for

• Uranium (U) was discovered in 1789 by Klaproth (German chemist) from mineral pitchblende (UO2) • Prior to discovery of fission of heavy elements demand for U was small. Used for color in glass & glaze in ceramics (No. Food placed on Fiestaware won’t cook itself!!) • Discovery of fission in 1938/1939 led to explosion in U demand and consequent development of U resources around the world. • Manhattan project used 6,000 tons of U

• 67% from Shinkolobwe Mine – , now DRC (up to 65% U3O8) • 17% from Canada • 14% from western CO . • Domestic U came from mines in western CO which mined carnotite (K2(UO2)2(VO4)2 1-3H2O) • Originally mined for Ra, price was then $70 K/g - $120 K/g ($3.0 M/g in 2020) • Mines switched to V for steel alloy, including re-processing of tailings • Mines switched to U ~1942, including re-processing of tailings

• Stunningly ironic that world class U reserves were found <150 miles from Los Alamos, NM

Monticello, UT U.S. Uranium Production

• Though U is surprisingly abundant, most domestic production occurred in western US • Early mining was in NW NM & NE AZ in small mines originally built for V • Discovery of ore in Poison Canyon by Paddy Martinez, 1950 led to first Grants Mining District mines in Grants Mineral Belt • Poison Canyon was named because high Se concentrations in plants killed livestock (Locoweed, Astragulus) • Se is associated with some U minerals • First big mine was Dysart No. 1 near Ambrosia Lake • 247 U mines in NM produced 36 M tons of ore, ~50% of total domestic production through 1990 • NM U industry in 1979 • 38 mines • 6 mills • ~7,000 employees • NM U industry today - No operating mines or mills

McLemore & Chenoweth, 2017 Mines & Mills in San Mateo Creek & Laguna Marquez Sub District

Gallup Sandstone • Most productive was Morrison Formation • Initially surface mines then underground mines were used to develop deeper ore bodies Dakota Sandstone • Underground mines required ventilation & dewatering • High levels of Rn increased risk of lung cancer by 3 to 6 times (less for non-smokers)

Morrison Formation

• Ambrosia Lake Sub-District Rio Algom Mill • ~100 mines (Kerr McGee) Phillips Mill • Bluewater Mill: 1953-1982 • Homestake Mill: 1957-1990 L-Bar Mill • Rio Algom Mill: 1958-2002 • Phillips Mill: 1958-1982 Bluewater Mill • Laguna & Marquez Sub-District • 3 mines (open pit) • L-Bar Mill: 1977-1981 Homestake Mill Jackpile Mine Open Pit Mining - Jackpile Mine (Laguna Pueblo)

• Largest open pit U mine in world located on SE flank of Mt. Taylor • 1953 – 1982 • ~7,868 acres in 3 pits • ~400 Mtons or ore • Deepest pit excavated to depth of 625 ft 1982 • Partial reclamation 1989-1994 • Declared Superfund site in 2013 due to airborne dust

2019

2019 2019 Mine headframe Underground Mines

• Dewatering estimates range from 170,000 AF to Mine water treatment ~500,000 AF in Grants Mining District • Water was treated before discharge but not put to beneficial use

• Large regional aquifer depletion Discharge to Arroyo del Puerto • Ore body aquifer was sole source of water for some communities • Several proposed projects It’s wet & dark down there! • Roca Honda mine near San Mateo • Churchrock near Gallup • Crownpoint in-situ leach (ISL) mine • Pilot ISL mine operated in 1979

UNC Church Rock Mine, 1990 Iron oxidizing bacterial growth U Milling

Water Ore Crushing & Grinding

• Acid leach process HSO 2 4 Oxidation & • Oxidize U(IV) to U(VI) Leaching e l

• Dissolve in H2SO4 c y c

• Recover by solvent extraction or IX e R

Countercurrent e • Precipitate U as yellowcake (U O ) t Decantation

3 8 a n i f • Alkaline leach was similar but used Na CO f Tailings Slurry

2 3 a

R (Sand, Slime &Liquids • >40 mills operated in US (DOE, 2014) Solvent Extraction Amine & Kerosene t e

• 7 mills operated in NM l n

c Feed e y v l • Bokum mill was built but never operated c o e S R

Stripping

UO3 8Precipitation Ammonia

Filtration, Drying & Packaging

Yellowcake

(UO)3 8

Bokum Mill 1982 Kerr McGee Mill 1990 U Mill Tailings

• Few regs to protect health & the environment until mid- 1970’s (e.g. no liners) • Most tailings piles predated NEPA & creation of EPA • U production was under authority of AEC • U production was national priority to support defense programs • Mill tailings were disposed in unlined (& unstable) piles as Sohio Mill,1982 slurry, typically 30% slimes • Churchrock tailings dam failure, 7/16/79 • Stunningly poor water quality Constituent SDWA MCL 4 Acid Mills 1 Alkaline Mill (mg/L) in NM in NM As .010 1.3 5.0

Mo 0.9 98.0 NH3 (as N) 400.0 16.0 Se .050 29,700. 8,400. U .030 74.0 14.0 TDS 500. 39,800. 25,400. pH 1.05 10.1 Ra-226 (pCi/L) 5. 70.0 58.0 Gross-α (pCi/L) 15.0 38,000. 6,700. Mill tailings water quality Thomson & Heggen, 1983 Tailings Piles Then and Now

Homestake, ~1965

Kerr McGee, 1981

Homestake, 1990

Kerr McGee, 33 M tons 2012 Homestake Superfund Site, 22 M tons, 2020 What is Future of Nuclear Power & U Development in NM?

• Nuclear power…. • Provides reliable carbon-free base load electric power • Has smaller environmental footprint than fossil fuels • Has an excellent safety record • Increasing support by environmentalists • Yet…. • Strong public opposition • Lasting impacts • NM has very large U reserves. Diagram of in-situ leach (ISL) (in-situ recovery – ISR) process • Future mines may include ISL mines • State needs to be prepared if U industry resumes

$50/lb $100/lb State Ore (M tons) % U3O8 U3O8 (M lbs) U3O8 (M lbs) Wyoming 145 0.076 220 446 New Mexico 64 0.14 179 390 AZ, UT, CO 22 0.145 63 198 Texas 15 0.089 27 40 Other 28 0.09 50 154 Total 274 0.098 539 1,228

References listed in: Thomson, B. (2020). The environmental legacy of and milling in New Mexico, The Geology of the Mt. Taylor Area, NM Geol. Soc. Spec. Pub. 14, Frey, B. et al. (eds.), Socorro, NM pp. 89-96, ISBN 978-1-58546-012-0