United States

Big Island (Ciner Trona) Complex

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Overview

Mine TypeUnderground
StatusActive
Commodities
  • Trona
Mining Method
  • Room-and-pillar
  • Continuous
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SnapshotSisecam Wyoming is one of the world’s largest producers of soda ash, serving a global market from its facility in the Green River Basin of Wyoming.

Big Island Mine complex consists of an underground Trona mine and associated refinery. The Trona deposits of SW Wyoming are the world’s largest occurrence of natural soda ash.
Related Asset

Owners

SourceSource
CompanyInterestOwnership
Natural Resource Partners L.P. 49 % Indirect
Sisecam Resources LP 51 % Indirect
Sisecam Wyoming LLC (operator) 100 % Direct
Sisecam Wyoming is owned by Sisecam Resources LP ("Sisecam") 51% and by NRP Trona LLC ("NRP") 49%. Sisecam Resources LP is the registrant. NRP Trona LLC, a wholly owned subsidiary of Natural Resource Partners L.P. ("NRP"). Sisecam Wyoming owns and operates the Big Island Mine complex that consists of an underground Trona mine and associated refinery.

As a result of the CoC Transaction, the Partnership changed its name to Sisecam Resources LP to be effective on February 18, 2022. The Partnership’s common units have traded on the New York Stock Exchange under the new ticker symbol “SIRE” since March 1, 2022. In connection with these changes, the general partner of the Partnership also changed its name to Sisecam Resource Partners LLC and Ciner Wyoming LLC changed its name to Sisecam Wyoming LLC, effective on February 18, 2022.

Contractors

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Deposit type

  • Sedimentary

Summary:

The trona deposits of SW Wyoming are the world’s largest occurrence of natural soda ash. The deposit was formed from the evaporation of a shallow lake, Lake Gosiute, thatcovered SW Wyoming and NE Utah 50-60 million years ago (wyomingmining.org, 2020). The trona mineral deposits within the Sisecam Wyoming lease area are correlated with the lacustrine sequences of the Eocene Green River Formation. Trona and otherassociated evaporates occur within the Upper Wilkins Peak Member. The lacustrine sequences of the Green River Formation were deposited in a series of lakes. Approximately fifty million years ago, Lake Gosiute, fluctuated in areal extent in response to climatic and tectonic events. At its smallest size, during restrictive phases, the lake was very saline and contained large quantities o fdissolved solids. When evaporation of the water reached critical levels, dissolved solids precipitated to form trona, shortite, halite, and other saline minerals. Trona formed as a chemical precipitate and required a specific range of weight percent of sodium and carbon dioxide in solution, a specific range of temperatures, and a specific range of relative concentrations of other ions (calcium, magnesium, chlorides, sulfates, etc.) within the water column. Sediments eroding from the peripheral mountains created extensive alluvial plains and broad flat pediments. Clastic wedges of the Wasatch and Bridger-Washakie formations intertongue and grade laterally with the lacustrine sequences of the Green River Formation. Within the hydrogeographic basin of approximately 77,300 km (48,500 square miles), the greatest expanses of Lake Gosiute and surrounding mudflats occurred during the Tipton and Laney stages. Bradley (1964) estimated the lake expanded to over 24,000 km (15,000 square miles). Total evaporation of Lake Gosiute during the restrictive phases of the Wilkins Peak stage is indicated by the presence of sedimentary structures in the deposit. TRONA BEDS OF THE GREEN RIVER BASIN The US Geological Survey recognizes 25 trona beds of economic importance (at least 1 meter in thickness and 300 km in areal extent) within the Green River Basin. Identified in ascending order, the trona beds are numbered 1 through 25 from the oldest (stratigraphically lowest) to the youngest (stratigraphically highest). Sisecam Wyoming has mineable reserves in the shallowest mechanically minable Trona Beds 24 and 25 (800 to 1,100-feet deep). Currently Genesis. Alkali, Solvay, and Tata are mining Bed 17 occurring at greater depth. Pacific Soda is focused on the lower trona beds, Bed 1 through Bed 4, utilizing solution mining due to the trona depth. Trona Bed 1 through 18 of the Lower Wilkins Peak are relatively tabular with a fine grain sugary appearance. Various amounts of halite are present and can become more salt, halite, than trona towards the southwestern portion of the depositional basin. Halite is a significant contaminate in the refining process and reduces recovery and increases production cost. A stable depositional environment is implied by uniformity and minimal variation of the depocenters of Beds 1 through 18. Trona Beds 19 through 25 are relatively halite free and consist of amber translucent coarse-crystalline blades to coarse granular “sugary” textured masses. Trona Beds 19through 22 are located in the northwestern corner of the Green River Basin saline depositional basin. Trona Beds 24 and 25, mined by Sisecam Wyoming, are located in the northeastern corner of the Green River Basin. Local Geology Mineral reserves within the Sisecam Wyoming lease area are confined to Trona Beds 24 and 25. Isotope analysis of a volcanic layer, known as the Big Island Tuff, located between these beds, has dated deposition at approximately 49 million years. Local structural gradient is oriented west/southwest at a grade of approximately 50-feet per mile and was influenced by the structural high of the Rock Springs Uplift to the east. Overburden depths of Beds 24 and 25 increases along the strike of the dip from typically 800-feet to 1,100-feet with increasing surface topography. Depositional and post-depositional sedimentary structures have been observed in the Sisecam Wyoming Mine and have had some impact on production grades and/or mining. These structures include: Polygonal, vertically oriented, clay filled features are common, suggesting intense evaporation and desiccation, resulting in the formation of large “mud-cracks” within the deposit. Sisecam Wyoming Bed 25 exhibits these features in greater detail than Bed 24. “Blow-outs” occurring in both beds, represent a massive dewatering event from vertical brine movement eroding the trona bed. Results of this movement have been observed to completely obliterate the beds from a 12-foot seam thickness to zero within a 50-foot distance span. Geological faulting, movement, and fracturing have been observed in Bed 25. The occurrence of locally identified “root-beer” seams is associated with this type of disturbance. Post-depositional dissolution from moisture/groundwater has been observed in the Lower Bed 24. Relatively isolated, the trona bed appears to be dissolved from the top after deposition, resulting in thinning of the bed and an increase in insoluble content in the upper portion of the seam.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnits20222021202020192018201720162015
Trona k tons  ....  Subscribe  ....  Subscribe  ....  Subscribe2,7522,6132,6672,6952,663
All production numbers are expressed as soda ash.

Operational metrics

Metrics20222021202020192018201720162015
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe4,157 k tons4,018 k tons4,001 k tons4,050 k tons4,040 k tons
Annual production capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe2.75 M tons of soda ash

Production Costs

CommodityUnits2020201920182017
Total cash costs (sold) Soda ash USD  ....  Subscribe 80 / ton   80 / ton   79 / ton  

Financials

Units202220212020201920182017
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 65.4   39.4   24.7  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 522.8   486.7   497.3  
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 107.1   106.3   89.5  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 130.9   103.3   113.5  
After-tax Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 101.6   103   86.4  
EBITDA M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 135.4   136.5   120.1  
Operating Cash Flow M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe 103.8   162.2   79.3  

Heavy Mobile Equipment

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Personnel

Mine Management

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EmployeesYear
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Aerial view:

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