Crystal Peak Minerals is developing the Sevier Playa potash project, a brine solution potassium mine, in Utah, US.
Feasibility study (FS) for the project was completed in January 2018 and the FS report was released in February 2018. The project is expected to be developed at a capital cost of £305m ($412m) and is expected to have a mine life of approximately 30 years.
It received record of decision (ROD) from the US Department of the Interior in August 2019. It is expected to produce 27,500 tons of sulphate of potash (SOP) a year in the initial three years and 337,500t of SOP from 2025.
Construction of the Sevier Playa project is expected to be commenced in 2019, while commissioning is exepcted in 2022.
Sevier Playa potash project location, geology, and mineralisation
The Sevier Playa property is situated approximately 225km to the south-west of Salt Lake city in Millard County, Utah. The site, approximately 42km-long and 13km-wide, extends over 130,000 acres and is located between the towns of Delta and Milford.
It is located on 48 federal potassium leases owned by CPM and 11 federal potassium leases owned by LUMA Minerals (LUMA). The Bureau of Land Management (BLM) granted CPM and LUMA access to the potassium leases through competitive bidding in April 2011.
Sevier Playa is an endorheic basin located within the Basin and Range physiographic province. The composition of the salt crust, which covers Playa, comprises evaporite minerals and is between 3 and 4 inches in thickness, which ranges up to 18 inches in certain areas.
The evaporite minerals on Playa surface are halite (NaCl), followed by galuberite and gypsum near the Playa shore. The Sevier Playa belongs to the terminal lakebed brine deposit, which is contained within Playa sediments comprising clay and marl.
The proven and probable reserves of the Sevier Playa potash project are 8.52 million short tons (7.73 million metric tonnes) of potassium sulphate (K2SO4). The produced reserves value is estimated to be 6.8 million short tons (6.17 million metric tonnes).
Mining and processing at Sevier Playa potash project
The Sevier Playa project will be installed with solar evaporation ponds for the precipitation of potassium-bearing salts. Brine recovery from the sedimentary basin will be undertaken using stepped extraction trenches as well as drilled wells.
Playa brine will be recovered from extraction trenches and wells and forwarded to the solar pre-concentration ponds to precipitate gangue material.
The recovered material will be precipitated in solar pre-concentration ponds with the resulting brine forwraded to the harvest ponds. The brine chemistry is then controlled in addition to the precipitation of potassium-bearing minerals, at the ponds.
The precipitated solids will be harvested and transmitted to the processing plant through haul trucks. The salts will be then crushed, slurried, and pumped before being converted into a single potassium-bearing mineral, which will be further upgraded and recovered at the flotation circuit.
The recovered potassium-bearing salt will be forwarded to the SOP crystallisers, wherein MOP brine will be added followed by re-crystallisation as K2SO4.
The K2SO4 produced will be dried, screened, and forwarded to either the compactor or load-out or to the bagging plant to produce granular, standard, or water-soluble products. The dry SOP product will be loaded onto haul trucks for transport to the rail load-out facility.
The processing plant can be reached from Delta on State Highway 257 through the existing Crystal Peak Road.
Electrical power for the project will be supplied by Rocky Mountain Power at 69kV from the Black Rock substation, wihc is located 74km to the north-east of the plant. A main substation will be built at the processing plant and a proposed substation on the north of Playa.
Four fresh water production wells of 300gpm capacity are planned to be drilled for the project.
Water required for non-potable needs will be sourced from a storage tank using individual pumps, while water for consumption and other potable water needs will be provided by bottled water.
Crystal Peak Minerals awarded the contract to prepare the feasibility study for Sevier Playa to Novopro Project, Norwest Corporation, and CH2M HILL Engineers.