This prefeasibility study examines the proposed development of a polyhalite deposit in southeastern New Mexico for the production of potassium sulfate and potassium-magnesium sulfate.
Report context
The Ochoa Prefeasibility Study NI 43-101 Technical Report, dated December 30, 2011, documents a prefeasibility study for the Ochoa Project located in Lea County, New Mexico. The project is held through a wholly-owned subsidiary, Intercontinental Potash Corp. (USA), and consists of 34 federal Bureau of Land Management potassium prospecting permits covering approximately 76,000 acres and 17 New Mexico State Land Office mining leases covering approximately 26,000 acres. As of the report date, the Ochoa Project was in advanced exploration status. The mineral resource estimate reported as of November 25, 2011, was updated to include data from seven new core holes drilled during the Phase 2B drilling program. This mineral resource estimate is compliant with NI 43-101 Standards of Disclosure for Mineral Projects and Canadian Institute of Mining, Metallurgy, and Petroleum (CIM) Definition Standards.
Processing route
Crushing and sizing
Much of the proposed process of transforming polyhalite into sulfate of potash (SOP) and langbeinite was based upon research from the U.S. Bureau of Mines in the 1930s. Detailed tests were performed on all aspects of the processing to determine that producing SOP from polyhalite is both economical and can be produced on a large scale. Polyhalite will first be crushed to minus 10 mesh, which was determined by initial testing to be the best size for extracting the potassium from the polyhalite.
Calcination
The second step of the processing is calcination, where the crushed polyhalite is heated to 480-520 degrees Celsius, with 500 degrees Celsius appearing to be optimum. This heating makes the potassium, magnesium, and sulfate contained in the polyhalite soluble in water for leaching. A rotary kiln was considered in the prefeasibility study; other options include vertical flash and fluid bed technology. The report notes that additional test work prior to the feasibility study is needed to determine the optimum equipment configuration.
Leaching and crystallization
After calcination, the material will be leached to dissolve the polyhalite, and the resulting brine will be sent to the crystallizer circuit. The crystallization circuit changed from use of evaporation ponds, previously considered in the Preliminary Economic Assessment, to Mechanical Vapor Recompression (MVR) in order to precipitate potassium sulfate and langbeinite from the solution.
Drying and granulation
The precipitated products are then dried and granulated to create a particle suitable for the market. Exhaust gases from the process will be scrubbed, and dust will be captured prior to discharging gases back into the atmosphere.
Plant design responsibility
The layout of the plant was generated by FLSmidth Salt Lake City, Inc., in July 2011. FLSmidth is responsible for the front-end processes, including crushing, milling, calcining, and leaching, and the back-end processes, including crystal drying, granulation, and on-site product storage. HPD, a subsidiary of Veolia Water Solutions & Technologies, is responsible for the evaporators and crystallizers using MVR and phase chemistry to produce langbeinite and SOP crystals.
Material transport
Finished product will be transported to a loadout facility in Jal, New Mexico, approximately 22 miles east of the processing plant. The study assumes ICP will run its own trucking fleet. The rail loadout facility will have its own electrical supply separate from the plant and mine.
Key reported parameters
| Parameter | Unit | Value | Basis |
|---|---|---|---|
| Crush size for leaching | mesh | Minus 10 | Testwork |
| Calcination temperature | degrees Celsius | 480-520 (optimum 500) | Testwork |
| Annual ore throughput | tons per year | Approximately 3,250,000 | Proposed design |
| Operating days per year | days | 337 | Proposed design |
| Annual SOP production | tons per year | 568,000 (normal level from 2018) | Proposed design |
| Annual langbeinite production | tons per year | 275,000 | Proposed design |
| Total SOP equivalent production | tons per year | 660,000 | Proposed design |
| Measured plus indicated mineral resource | million tons | 838.2 at 80.3% polyhalite (5-ft minimum thickness) | Resource estimate |
| Proven plus probable mineral reserves | million tons | 414.5 at 83.98% polyhalite | Reserve estimate |
| Mining extraction rate (normal) | percent | 90 | Proposed design |
| Mining extraction rate (near wells) | percent | 60 | Proposed design |
| Processing plant initial capital | US dollars | $481,392,000 | Proposed design |
| Total initial capital | US dollars | $705,568,000 | Proposed design |
| Average annual operating cost per ton of product | US dollars | $147.31 | Proposed design |
| Average annual mining operating cost | US dollars | $24,033,000 | Proposed design |
| Average annual processing operating cost | US dollars | $85,946,000 | Proposed design |
Project website: https://www.nafinance.com/zGetCompanyProfile.aspx?tradedSymbol=Icp&langCd=En
Technical qualifications
The prefeasibility study is based on a proposed 40-year mine plan with a forecast sale price of $623 per ton of finished product over the life of the project. Operating costs were determined from a variety of sources that included estimates from vendors, FLSmidth, HPD, Gustavson's historical and internal cost estimates, the InfoMine USA Mine and Mill Equipment Cost Estimators Guide, and ICP employees' first-hand knowledge and information of potash operations in the Carlsbad region. Processing costs for the plant were determined by FLSmidth for all areas excluding the crystallizer portion, and HPD determined the operating costs for the crystallizer portion. Major component rebuild costs are not included within the operating costs as these items are capitalized as sustaining capital. The report notes that additional test work prior to the feasibility study is needed to determine the optimum equipment configuration for calcination.
Source: Ochoa Project Prefeasibility Study NI 43-101 Technical Report, December 30, 2011, Sections 1.9 Processing and related processing sections.
