|
Salt Lake City Mill Site (Preliminary)
Salt Lake County, Utah
| Years of Operation |
Status of Mill
or Plant Site |
Uranium Ore
Processed
(Million Short Tons) |
Production
(Million Pounds U3O8) |
| 1951-1968 |
Decommissioned |
1.69 |
9.57 |
Mill/Plant Area
(Acres) |
Disposal Cell
Area
(Acres) |
Disposal Cell
Radioactive
Waste
Volume
(Million Cubic Yards) |
Disposal Cell
Total Radioactivity
(Ci, 226Ra) |
Disposal Cell
Average Tailings
Radioactivity
(pCi/g, 226Ra) |
UMTRA Project
Final Cost
(Million Dollars) |
| 128 |
54 |
2.80 |
1,550 |
481 |
94.17 |
Location: The Salt Lake City mill site, known also as the Vitro mill site, is located south of Salt Lake City, Utah, within the metropolitan area.
Background: In 1951, Vitro Corporation of America purchased the old Kalunite Plant that had produced alumina from Utah clays during World War II. Vitro converted the plant to a sulfuric-acid leaching process for treating uranium ore, and it became known as the Salt Lake City mill. From May 1952 to January 1964, the mill shipped uranium concentrate under three procurement contracts to the U.S. Atomic Energy Commission (AEC). The old alumina plant’s ore roasters were retained, and uranium ores with high carbonaceous content were roasted to improve the ore processing characteristics. The initial uranium milling process included acid leaching of the ore, countercurrent decantation, and precipitation of a uranous-phosphate product. During 1957, the mill was converted to a unique solvent extraction process that also permitted the recovery of small quantities of byproduct scandium. The mill’s initial capacity of about 100 tons of ore per day (TPD) was expanded several times, so that by 1957 milling capacity was 600 TPD. Over the AEC contract years, the mill processed about 1.7 million tons of ore and produced nearly 9.6 million pounds U3O8. All but a few pounds of the U3O8 product was sold to the AEC.
|
|
The Salt Lake City mill was operated mainly as a custom mill. Most of the ore processed was received from independent mines in southeastern Utah, though ore was also received from mines in several western states. From 1953-1958, uranium ore purchased under an AEC’s ore-buying program was stockpiled at the mill site. The AEC-purchased ore, along with ore from other AEC buying stations in the Utah region, was later sold to Vitro and processed at the mill. The uranium ore processed at the mill from 1953-1955 contained appreciable vanadium (averaging 0.7 percent V2O5), but it was not recovered during the years in which the mill supplied uranium to the AEC. When the mill was closed in 1964, the uranium ore remaining at site (about 58,000 short tons) was sold to the Atlas Corporation and transported to the latter’s mill at Moab, Utah. After uranium production was phased out, Vitro converted the Salt Lake City mill to recover vanadium by processing a waste product obtained from an elemental phosphorus production plant in Idaho. The Salt Lake City mill site was permanently closed in 1968. From its uranium ore processing, the Salt Lake City mill generated about 1.7 million tons of tailings. When the mill was closed down in 1968, the sites two piles held about 2.6 million tons of tailings material. Clean up of the mill site was begum in 1968. By 1970, the mill structures were demolished except for a 450-foot tall stack, a railroad spur, and a water tank. Radioactively contaminated soil and was excavated and shipped to other mills.
UMTRA Surface Remediation: The Salt Lake City mill site is located in the South Salt Lake urban area just south of Salt lake City. A natural wetlands area lies nearby east of the site. On the north, a natural creek boarders the site, and the Jordan River flows less than one-half mile west of the site. The site is underlain by lake-bed sediments consisting of poorly drained sand, clay, and silt. The mill and related structures were located on 8 acres in the eastern portion of the site. The western 120 acres were used for tailings storage. The tailings impoundment ponds were formed by earthen-dams that were built from soil and sediments excavated from the mill site. The tailings piles thus extended about four feet below the natural grade and stood up to 16 feet high in places. The mill site reclamation work was performed between February 1985 and June 1989 by the State of Utah under the direction of the U.S. Department of Energy. The mill structures remaining at the site were demolished. About 2.8 million cubic yards of tailings, radioactively contaminated soil material, and debris from the site were transported by rail and truck to the South Clive Disposal site for stabilization. Included in that volume material recovered from the 119 vicinity properties in the Salt Lake City and nearby areas that were cleaned up during the surface restoration project.
Responsibility for Remediation: U.S. Department of Energy, initially; completed by the State of Utah.
Stewardship:
Disposal Area: Remedial activities began at the Salt Lake City mill site in February 1985 and were completed in June 1989. Contaminated materials that remained at the site were excavated and relocated by rail and truck to the South Clive disposal cell, a new site acquired by the State of Utah and located 85 miles west of Salt Lake City. Rectangular in shape, the 54-acre cell’s base is 5-feet below grade and its top rises to 35 feet the local terrain. Covering the cell is an engineered 9-foot thick, multilayered soil and rock cap. The radon barrier is a silty-clay layer, 7-feet thick; a 6-inch sand layer serves as the bedding layer for the 1.5-foot thick rock cap designed to protect against bioerosion from plant and animal intrusion.
Groundwater Program:
|
|
