The mine taps under Lake Erie into the F1 unit of the Salina Formation, which is more than 70 feet (21m) high in the area.[4][5] According to mine manager Bob Supko, it is unusual for a salt mine to be located in an urban area (downtown Cleveland), but it keeps supply close to Cargill's business.[6] The location is leased from the State of Ohio,[7][8] and royalties are paid to the state and the City of Cleveland per amount of salt mined.[5]
Access to the mine is on the shore of Lake Erie on Whiskey Island, where the above-ground facilities are located.[9] The mine dives through limestone to a depth of 1,793 feet (547m),[5] a four-minute trip by elevator,[10] before expanding horizontally under the lake, which is only 56 feet (17m) deep here.[11][9] The mine has grown significantly over the years, from 4 square miles (10km2) in 2013[9] to 12sqmi (31km2) in 2016[11] to 16sqmi (41km2)as of 2023[update].[10] The temperature inside remains around 70°F (21°C) year-round.[6][10]
Operations
Mining takes place using the room and pillar system.[8] Salt is removed by drilling holes filled with ammonium nitrate, an explosive,[10][6][9] then transported by conveyor belt and cut before it is lifted to the surface.[6] Pillars are left behind for support and allowed to flex in a technique called "yielding pillar".[8] There are hundreds of rooms in the mine, and each room has a height of about 25ft (7.6m) and an area of about 45sqft (4.2m2).[12] They branch off east and west from a 4-mile (6.4km) primary tunnel extending to the north.[10] According to engineer David Harris, "it’s surprisingly similar to how it was mined 50 years ago".[10]
As of 2023[update], there were 223 workers at the mine.[10] The miners are members of the union Teamsters Local 436.[9] Equipment is transported down the mine in pieces and, once assembled, remains underground forever.[6][13] Maintenance is also performed underground.[13] The low humidity prevents the machinery from quickly rusting.[10]
Yield
The average yield is 12,000 short tons (11,000t) per day.[10] According to engineering manager Bob Nelson, demand for salt is relatively stable compared to other parts of the mining industry.[10] Superintendent Nick Newsome claims that "about 80 percent of our production goes to de-icing control".[6] Salt is also used in the manufacture of a wide variety of materials.[5] The mine supplies salt across the Snow Belt and was the largest supplier for Ohio in 2012.[9]Shipping by boat takes place from April to the end of the year.[10]
As of 2013[update], reserves are expected to last for another 100 years.[6]
History
For most of the 19th century, Cleveland relied on salt from Youngstown or out-of-state.[5] The present deposit was discovered accidentally in 1886 when drilling for natural gas.[5] Construction of the mine began in 1958 by the International Salt Company.[7] Production began in 1962,[4][7] and the company would be renamed Akzo Nobel Salt following an acquisition.[7] The mine was acquired by Cargill in 1997.[9] The company launched a $13.8 million expansion of operations in 2010.[9]
On August 19, 2013, the mine was shut down indefinitely after the discovery of a potential cave-in threat.[9][1] Sensors had detected a convergence, or narrowing between the floor and ceiling, measuring fractions of an inch.[8] Local geologists suspected that it was caused by weight sagging above and predicted that the closure would not be permanent.[8] Below-ground workers were given paid leave[1][9] while the company brought in consultants from the Ohio Department of Natural Resources (ODNR) and the Mine Safety and Health Administration (MSHA).[18] Above ground operations, including shipping, were not affected.[9] Operations gradually resumed starting ten days later after determining that the affected area was isolated.[12][18]
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
