IC Potash's March 2014 feasibility study for the Ochoa project in Lea County, New Mexico, expects 82.24% overall recovery from 3.69 Mt a year of run-of-mine ore.
The NI 43-101 Technical Report, Ochoa Project Feasibility Study, Lea County, New Mexico, was compiled by SNC-Lavalin and Agapito Associates for IC Potash Corp., with an effective date of January 9, 2014 and a report date of March 7, 2014. The plant design rests on ICP's metallurgical testwork. It processes conventionally mined polyhalite ore into sulphate of potash (SOP) products through crushing, washing, calcining, leaching, crystallization, drying and granulation.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | January 9, 2014 | Not applicable | SNC-Lavalin and Agapito for IC Potash Corp. |
| ROM feed | 3.69 | Mt/a | Not applicable |
| Ore composition | 80.0% polyhalite, 7.68% magnesite, 6.9% anhydrite, 5.42% halite | Not applicable | Not applicable |
| SOP production | 714,400 | t/a | Plant utilization 90.32% |
| Recovery by area | 96.5 crush/wash, 99.8 calcine, 95.0 leach, 90.8 crystallize, 99.0 granulate | % | Not applicable |
| Overall recovery | 82.24 | % | Not applicable |
| Nominal products | 312,500 t/a standard and 312,500 t/a granular SOP | Not applicable | Plus soluble SOP |
| Granulation | Two circuits of 192,500 t/a | Not applicable | Second added in Year 2 |
| Ore top size | 4 inches | Not applicable | Roll crushed to below 1 inch |
| Calcination | Fluid bed, about 860 to 986°F | Not applicable | Above 986°F leachability drops |
Overview
The plant runs crushing and washing to remove sodium chloride, calcining to make the ore leachable, two-stage countercurrent leaching to a potassium sulphate brine, and crystallization by mechanical vapour recompression (MVR) and multiple-effect evaporation (MEE), followed by drying, sizing and granulation. Each area's recovery is taken from testwork, pilot work or industry standards, and together they give an overall recovery of 82.24%. The plant can produce soluble, standard and granular SOP.
Key Process Stages
Crushing and washing. Conveyors carry ore from the mine to two surge bins holding ten hours of mine output. A roll crusher reduces the ore from 4 inches to below 1 inch. Recycled water slurries it, and a wet sizing screen sends oversize to a Cage-Paktor. The ore contains about 5.4% sodium chloride in thin discrete layers. Left in the system, the salt would cause corrosion during evaporation and threaten product grade. Testwork showed it is freed by crushing and dissolves quickly, so it is leached out in the crushing circuit and a salt leach tank. Hydrocyclones and vacuum belt filters then separate and wash the solids, and the salty purge is sent by pond to deep well injection.
Calcination. Fluid-bed units, chosen for close control of temperature and residence time, heat the polyhalite in three stages. The first stage drives off free moisture and the second, at about 320°F, the water of crystallization. Above about 860°F, molecular rearrangement forms a leachable solid solution containing the potassium and magnesium sulphate. Above 986°F, further reactions reduce leachability. Fluid-bed coolers then cool the calcine, and five hours of surge capacity buffers the leach.
Leaching. Two countercurrent stages of four agitated vessels each, held near boiling with steam because the reaction is endothermic, dissolve the calcine. Primary leach brine passes through hydrocyclones and solid bowl centrifuges. The secondary stage, using recycled condensate, recovers the remaining potassium sulphate, and its solids are trucked to tailings. Extra clarification equipment was added because pilot work showed sub-10 µm particles in the brine.
Crystallization. Leonite precipitated at the end of the process is redissolved in the leach brine, which concentrates it and raises the potassium sulphate fed to the SOP crystallizers. Polyhalite seed removes calcium supersaturation to prevent scaling. A single MVR forced-circulation pre-concentrator then raises the potassium and magnesium concentration before SOP crystallization.
Product finishing. Crystallized SOP is dried and sized as standard and soluble products, and granulated in two 192,500 t/a circuits, the second added in Year 2.
Additional Interesting Data and Summary
The report gives product capacities of 250,000 to 503,000 t/a of standard SOP and 250,000 to 385,000 t/a of granular SOP, with nominal production of 312,500 t/a of each, alongside a soluble SOP product.
In summary, the 2014 Ochoa feasibility study is a polyhalite-to-SOP flowsheet in which the key steps are washing out halite, carefully controlled fluid-bed calcination to unlock the potassium, and evaporative crystallization with leonite recycle, for 82.24% overall recovery.
Key Processes
- Roll crushing and Cage-Paktor size reduction
- Halite washing with hydrocyclones and vacuum belt filters
- Fluid-bed calcination and cooling
- Two-stage countercurrent leaching with centrifuge separation
- Brine clarification
- Leonite dissolution and polyhalite seeding
- MVR and multiple-effect evaporative crystallization
- Drying, sizing and granulation of SOP
Source: NI 43-101 Technical Report, Ochoa Project Feasibility Study, Lea County, New Mexico, USA, compiled by SNC-Lavalin and Agapito Associates for IC Potash Corp., effective date January 9, 2014.
Earlier report summaries
Earlier versions of this profile, based on older technical reports, are retained below for source traceability. Dates and figures reflect each report’s own effective date and are superseded by the current information above.
Ochoa Project — 2011 Technical Report
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.
