Mining Slated To Begin At World’s Largest Known Borate Deposit At Fort Cady

American Pacific Borates and Lithium Limited is purposed to initiate operation of what is believed to be the third largest boric acid mining project in the world at Fort Cady in San Bernardino County’s Mojave Desert.
The mine is located approximately 30 miles east of Barstow and two-and-four-tenths miles south of Interstate 40.
American Pacific Borates and Lithium Limited is working what is the world’s largest known borate deposit, with an estimated mineral resource of 120.4 million tons. In total, over $80 million has been spent on the Fort Cady project, including license acquisition, drilling and resource estimation, well testing, metallurgical testing, feasibility studies and pilot plant infrastructure. In addition, the project has previously obtained all operating and environmental permits required for commercial solution mining operations.
Duval Corporation evaluated the Fort Cady deposit in the late 1970’s and early 1980’s, completing over 30 diamond drill holes upon which the maiden resource estimate was defined. An additional 17 production wells were completed in the following years which were used for injection testing and pilot-scale operations.
The project will be developed in three phases with an estimated investment of $526 million. Phase one is now approaching operational status, while phases two and three are expected to be operational by the second quarter of 2023 and the second quarter of 2025, respectively.
The mine site encompasses an area of a half square mile.
The Fort Cady deposit lies in the Hector Basin in the central Mojave region. The project area has uniform exposures of fine-grained lacustrine sediments and tuffs with younger alluvium occurring in washes and overlying the older lacustrine sediments.
The entire mineralized zone, irrespective of grade cut-off and minor barren interbeds, ranges up to 400 feet in thickness. The borate mineralization occurs in the form of colemanite and is found in thinly laminated silt, clay, and gypsum beds.
The Fort Cady project has proven reserves of 27 metric tons, grading 6.70 percent boron trioxide, B2O3, 11.91 percent boric acid, H3BO3, and 379 parts per million of lithium as of December 2018. The probable reserves are estimated at 13.8 metric tons grading 6.40% boron trioxide, B2O3, 11.36% boric acid, H3BO3, and 343 parts per million of lithium.
The project employs a solution mining method carried out at the site of the deposits intended to recover boric acid. A push and pull method is currently employed and will continue until the wells naturally connect, after which separate injection and recovery wells will be used.
A hydrochloric acid solution is injected into the ore body, 1,394 feet below the surface through the wells. The solution leaches the colemanite ore to form a pregnant leach solution, which is extracted through reverse pumping.
The pregnant leach solution is processed and filtered to remove insoluble impurities by passing it through a solvent extraction circuit, followed by washing and stripping circuit. The final stripped liquor is filtered and directed to the crystallization circuit.
The crystallizer produces slurry containing 28 percent liquid boric acid by weight, which is directed to the dewatering circuit. The boric acid liquor is filtered, concentrated, and crystallized by evaporation. The crystallized boric acid is dried and bagged as a final product.
The site is accessible from the I-40 Hector turn-off and Route 66. A pipeline has been constructed to connect the processing plant to the existing Pacific Gas and Electric Company mainline for supplying natural gas for the project.
Power is sourced from an eight megawatt steam turbine type generator. Water is supplied from two existing water wells in the area. Four new wells are proposed to supply 100 gallons per minute of process water required for the operations when it reaches full capacity.
Barr Engineering, an engineering and environmental consulting services company, was engaged to work on the mineral processing program. .
The geotechnical and water management consulting firm Piteau Associates was contracted to prepare a detailed mining plan for Fort Cady while RESPEC Consulting certified the identified mineral resource estimates into verified ore reserves.
Process solutions company Millcreek Engineering was engaged to conduct basic engineering for the Fort Cady project.
The combined environmental impact statement and environmental impact report for the plan of operations was issued by the Department of the Interior, Bureau of Land Management, and the mining conditional use permit and approved reclamation plan was issued jointly by the San Bernardino Land Use Services Department and the California Department of Conservation, Office of Mine Reclamation.
Ultimately, approximately 80 employees are to be involved on-site at the operation.
-Mark Gutglueck

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