In addition to the open pit mining operations, Atlantic City Ore Operations included an ore crushing and screening facility; a concentrating plant; an agglomerating plant; an extensive water storage and handling system; and storage, loading, and shipping facilities, including a 76-mile industrial spur track. Iron ore agglomerates were shipped to the blast furnaces at Geneva Works in Provo, Utah by the Union Pacific Railroad.
Construction was completed in 26 months, with initial startup of plant operations in August 1962. Full production was achieved by March 1963. Operations were suspended indefinitely October 1, 1983, and in April 1984, the plant was permanently shut down.
On June 30, 1960, U.S. Steel Corporation's Columbia-Geneva Steel Division broke ground for the construction of facilities to mine, concentrate, and agglomerate iron ores of the Atlantic City, Wyoming area, which became known as the Atlantic City Project. The project, named for a nearby ghost mining town, was located in Fremont County, 28 miles south of Lander, on the southeast flank of the Wind River Mountains. The installation was the highest open pit iron ore mining operation in the United States, operating at an elevation of 8300 feet, 16 miles north of South Pass, where the Oregon Trail crossed the Continental Divide. It was the first integrated iron ore beneficiation plant west of the Mississippi producing an agglomerated product.
In addition to the open pit mining operations, Atlantic City Ore Operations included an ore crushing and screening facility; a concentrating plant where the low grade taconite-type ore was magnetically upgraded; an agglomerating plant; an extensive water storage and handling system built to recover most of the process water and recirculate it back through the mills; and storage, loading, and shipping facilities, including a 76-mile industrial spur track to Winton Junction, 10 miles north of Rock Springs. Iron ore agglomerates were shipped to the blast furnaces at Geneva Works in Provo, Utah by the Union Pacific Railroad, where they were then converted into a variety of high-grade steel products.
Construction was completed in only 26 months, with initial startup of plant operations in August 1962. Full production was achieved by March 1963. Operations were suspended indefinitely October 1, 1983, but in April 1984, the plant was permanently shut down and the stripping dumps, pit, and tailings basin reclaimed.
Initially, Geneva Steel Works drew its raw materials from an iron ore mine at Cedar City, Utah. That mine proved insufficient to keep Geneva Steel Works operating at full capacity, so U.S. Steel sought a secondary source of iron ore. Owing at least in part to a geological report issued jointly by the Geological Survey of Wyoming and the University of Wyoming Natural Resources Research Institute in 1949, U.S. Steel became aware of a large reserve in the Wind River Mountains in Wyoming, north of Atlantic City and south of Lander. The reserve was more than 75 miles away from the Union Pacific Railroad's line in southwestern Wyoming, and it would require a 300-mile trek by rail to bring the iron ore from the reserve to the Geneva Steel Works.
Undaunted by those distances, U.S. Steel in the mid-1950s began planning the creation of the Atlantic City iron ore mine, to be an open-pit mine with on-site agglomeration facilities. The mine was located some 8,300 feet above sea level. Work began in 1960 on the mine complex and the 76.7-mile railroad. The mine and railroad were constructed by contractors J.H. Pomeroy & Co. and Bechtel Corp.
U.S. Steel enlisted the Union Pacific Railroad's civil engineers to design the railroad, which was completed in 1962. The line's construction disproved a theory put forth in the October 1947 issue of Trains magazine that held that no more railroad lines ever would be built to cross the Continental Divide in the Rocky Mountains. The taconite pellet plant began operations in August 1962, with the first shipment departing the site on August 15, 1962.
The line began at a connection with the Union Pacific at Winton Junction, north of Rock Springs, and extended north and then northeast, snaking past the west side of South Pass City and then turning northeast before concluding at the mine. From the mine's loading chute at its north end to the connection with the Union Pacific at Winton, the line descended 1,884 feet in elevation, including dropping 880 feet alone in the first 13 miles between the mine and the Continental Divide at South Pass. Construction of the line required fills as high as 100 feet between the mine and the Sweetwater River. In that segment, grading contractors moved more than 2.5 million cubic yards of material. Below South Pass, civil engineers encountered a peat bog across the route, which was unusual for such an arid climate. The solution was to dig deep under an impervious layer of soil to drain the subgrade.
The railroad's motive power was F7 locomotives that U.S. Steel reallocated from a common carrier railroad in Pennsylvania that the company had owned at that time, the Bessemer & Lake Erie. The railroad initially "leased" the locomotives from the B&LE before purchasing them outright.
The mine operated for three shifts each day - thus never shutting down - and employed 550 employees, and the railroad normally carried a full train out of the mine every other day. At the mine, U.S. Steel extracted a hard, slate-like rock called magnetic taconite, which was only about 30 percent iron. After the taconite was blasted from the pit walls, it was crushed several times and then strong magnets pulled the iron out of the taconite. Then, the concentrated iron ore was agglomerated, which involved mixing the iron ore - which at that point was a cake-like mixture - with bentonite, rolled into marble-sized pellets and heated in an agglomerating furnace at the mine. Finally, the pellets were stored on-site in a building until they were shipped out in 120-car trains. The operation was the highest open pit iron ore mining operation in the U.S.
Wyoming Highway 28 subsequently was rerouted through the old mine site, and the mine's pits today have become filled with rainwater and melted snow. Locomotive-wise, the railroad had four F7 A units and four F7 B units. Seven of the railroad's eight locomotives - all except the F7A unit bearing the number 734 - formerly had been on the roster of the Bessemer and Lake Erie, while F7A No. 734 formerly had been a Burlington Northern Railroad locomotive and prior to that had been on the roster of the Northern Pacific Railway. The seven former B&LE units were used for hauling the taconite pellets, while No. 734 was purchased as a parts source and never was used in active ore service. Those seven former B&LE locomotives all went first to the Texas Southern railroad. Three units - 723B, 724B and 726B - eventually were scrapped. Four other locomotives - 712B, 723A, 724A and 726A - found homes elsewhere. 712B, 723A and 724A all later became property of the Washington Central Railroad, while 726A fell into the hands of Passenger & Freight Locomotive in San Antonio. No. 734, the former Burlington Northern unit, was bought by railroad photographer Dale Sanders in September 1983.
The reopening of the mine was discussed again in 2014, after the Wyoming Business Council began investigating the feasibility of reopening the mine. Reopening of the mine, whose mineral rights are owned by the J.R. Simplot Company, would entail building a new rail line to transport the ore.