Grand Junction (Climax Uranium) Mill

Location: The Grand Junction (Climax Uranium) mill site is located in the City of Grand Junction, Mesa County, Colorado.

Background: In 1950, the Climax Uranium Company signed a uranium concentrate purchase contract with the U.S. Atomic Energy Commission (AEC) for a uranium mill located at Grand Junction, Colorado. The mill was located on a 200-acre tract on the north bank of the Colorado River in an industrial area of the city. This mill was the first in the United States built primarily for uranium production with secondary vanadium production. The mill (Grand Junction Mill 1 under UMTRA) began operation in 1951 and produced uranium for sale to the AEC under two contracts through December 1966. The mill was designed for a throughput capacity of 100 tons of ore per day (TPD); it was increased to 500 TPD by 1955. In its early years, the mill used the newly developed acid-leach/uranous phosphate precipitation process that, in pilot scale, yielded a high-grade uranium cake (concentrate) product. In full-scale operations, however, the cake product was of lower than expected grade. In 1956, uranium precipitation was changed to a hydrogen-peroxide process, and afterwards the mill produced a high-purity uranium cake product. Climax also changed to a solution-extraction process for uranium-vanadium separation about that time. The mill feed consisted of carnotite-type ores from a large number of mines in the Uravan mineral belt area of western Colorado. During the AEC contract years, the mill processed about 1.8 million tons of ore that averaged 0.28 percent U3O8 and 1.35 percent V2O5. During periods when the vanadium market was soft from mid 1957 to mid 1959, the mill’s production of vanadium in excess of commercial sales was also purchased by AEC. Climax’s last AEC uranium-procurement contract expired at yearend 1966, and afterward the mill continued to produce uranium and vanadium for the commercial market. The mill was permanently closed in March 1970. During the post-AEC years, the mill treated about 0.5 million tons of ore that averaged 0.26 percent U3O8 and 1.63 percent V2O5. In 1970-1971,Climax dismantled most of the mill, and equipment that could be decontaminated was sold. The tailings pile was contoured, covered with top soil, and seeded to establish a cover of vegetation. Over the mill’s lifetime, 1951 to 1970, nearly 2.3 million tons of ore were treated and about 11.7 million pounds U3O8 and 46.1 million pounds V2O5 were produced.

In the early1970s, an industrial park was established on an 85-acre parcel of the Climax mill site. A 40-acre tract was ceded to the State of Colorado. A 10-acre tract became private property.

In the 1950s and 1960s, uranium mill tailings from the Climax mill had been made available to the public. An estimated 300,000 tons of tailings were ultimately used in construction as a sand substitute or for backfill material at various sites throughout the Grand Junction and Mesa County area. These sites later became known as "vicinity properties." In 1972, Congress passed Public Law 92-314 (amended by P.L. 95-238) to provide funding and authority for a Federal/State program to perform remedial action on Grand Junction sites where uranium mill tailings were used, including private residences, schools, churches, and commercial locations. Relocation of tailings under the Federal program began in 1973, and the excavated materials were temporarily stored on the 40-acre State-held tract pending final burial. Under this cooperative program with the State of Colorado, the Government was responsible for 75 percent and the State 25 percent of the remediation cost.