Allana Potash's April 2013 resource update for the Danakhil potash project in Ethiopia's Afar State describes two 500,000 t/y lines with an overall process recovery of 84%.
The Technical Report, Resource Update for the Danakhil Potash Project, Danakhil Depression, Afar State, Ethiopia, was prepared by ERCOSPLAN for Allana Potash Corp. with an effective date of April 17, 2013. The plant is designed to produce one million tonnes a year of dry KCl product at 95% purity, running continuously for 7,500 hours a year, with the remaining hours set aside for scheduled maintenance. Brine from solution mining is evaporated in solar ponds, and the harvested salt is milled, floated and leached to grade.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | April 17, 2013 | Not applicable | ERCOSPLAN for Allana Potash Corp. |
| Product | 1,000,000 | t/y | 95% KCl (MOP); two lines of 500,000 t/y |
| Operating hours | 7,500 | h/a | Not applicable |
| Product composition | 95.4% KCl, 2.7% NaCl, 1.1% CaSO4, 0.6% insolubles | Not applicable | Not applicable |
| Overall process recovery | 84 | % | With surplus brine recirculated |
| Water to caverns | About 1,250 | m³/h | Production brine about 1,200 m³/h |
| Crystallisate KCl content | About 32 | % | Feed to the plant |
| Rougher concentrate | About 58 | % KCl | Not applicable |
| Process water | About 315 | m³/h net | 2.36 Mm³ a year; about 267 m³/h for cold leaching |
| Wet tailings | About 2 | Mt/y | Mainly NaCl |
| Salt conveyor | About 9 | km | From the pond hoppers to the plant |
Overview
Groundwater from a well field is piped to caverns to dissolve the sylvinite, and the production brine is pumped to solar evaporation ponds. In the first pond, halite crystallizes. The remaining brine moves to a second pond, together with surplus reclaim brine from the plant, where it is almost completely evaporated to a wet salt of sodium and potassium chlorides. Wheel loaders harvest the salt and trucks take it to three hoppers, from which a conveyor of about 9 km carries it to the wet salt store at the plant.
The plant screens and mills the crystallisate, then floats the KCl in rougher, scavenger and cleaner stages. Cold leaching with KCl-bearing brine raises the product to 95% KCl. The product is dried and screened. Coarse product is stored for trucking to the port of Tadjoura, and fines are dissolved and reused as wash water. Because surplus reclaim brine returns to the KCl ponds, its contained KCl is recrystallized and refloated, giving an overall process recovery of 84%.
Key Process Stages
Solution mining. About 1,250 m³/h of water is fed to the caverns, and about 1,200 m³/h of production brine is pumped to the ponds. Part of the brine may come from cavern brine replacement, which slightly reduces the water needed.
Two-step solar evaporation. Sodium chloride crystallizes first. The brine, about 890 m³/h, then passes to the second pond with about 430 m³/h of surplus reclaim brine, where halite and sylvite crystallize.
Crystallisate treatment. Screening reduces the load on the mill and avoids overgrinding the fines. Milling liberates KCl crystals intergrown with NaCl so that the collector can attach to them. The milled salt is repulped with reclaim brine and wet screened, with coarse material sent through wet milling and back.
Flotation. Rougher flotation takes feed of about 32% KCl to a concentrate of about 58%, which goes to cleaner flotation. Rougher tails are screened. The undersize goes to the tails leach tank, and the oversize, with KCl not yet fully liberated, is crushed and floated again in the scavenger stage.
Cold leaching, debrining and drying. The flotation concentrate is cold leached with water and debrined to reach 95% KCl, then dried with fuel oil or gas and screened.
Tailings. The process generates about 2 Mt/y of wet tailings, mainly NaCl, much of which is to be placed on the salt plain and used for road and dyke construction.
Additional Interesting Data and Summary
Net process water for 1 Mt/y of MOP is about 315 m³/h, or 2.36 million m³ a year, and about 267 m³/h of it goes to cold leaching, which is needed to reach 95% KCl. The process produces surplus saline brine, saturated in KCl and NaCl, which is returned to the ponds rather than discharged.
In summary, the 2013 Danakhil design is a solar evaporation potash flowsheet. Solution-mined brine is concentrated by the sun in two steps, and the harvested salt is upgraded by flotation and cold leaching to a 95% MOP, with recycled brine lifting the overall recovery to 84%.
Key Processes
- Solution mining of sylvinite
- Two-step solar evaporation (halite, then halite and sylvite)
- Screening, milling and wet milling of crystallisate
- Rougher, scavenger and cleaner KCl flotation
- Cold leaching and debrining to 95% KCl
- Drying, screening and fines recycle
- Surplus brine recirculation to the ponds
Source: Technical Report, Resource Update for the Danakhil Potash Project, Danakhil Depression, Afar State, Ethiopia, ERCOSPLAN for Allana Potash Corp., effective date April 17, 2013.
Consolidated report summaries
The following former standalone pages about this operation were consolidated here in October 2026. They are retained for source traceability; dates and figures reflect each report’s own effective date and may be superseded by the current information above.
Danakhil Potash Deposit — 2011 Technical Report
This report describes three conceptual processing options for potassium chloride recovery from the Danakhil potash deposit, each based on different mining and beneficiation approaches.
Report context
This 2011 technical report presents proposed recovery methods for the Danakhil potash deposit located in the Afar State of Ethiopia. The report details three processing options: flotation of open-pit mined sylvinite (Option 1); solar and thermal evaporation of solution-mined brine (Option 2); and solar evaporation followed by flotation of crystallized material from solution mining (Option 3). Each option is designed for a production capacity of 1 million tonnes of KCl per year, with the plant operating continuously for 7,500 hours per year.
Processing route
Option 1: Flotation of Material from the Open Pit
This option assumes open-pit mining, producing a KCl-containing solid feed. Processing stages include raw ore treatment, desliming, rougher flotation, cleaner flotation and leaching, scavenger flotation, reclaim brine and brine disposal, effluent flotation, and KCl product debrining, drying and screening. The dry KCl product is planned to have a purity of at least 95%.
Raw ore is stored in a bunker, then screened to separate material for crushing from material for direct repulping. Crushing liberates KCl crystals intergrown mainly with NaCl. The crushed salt is mashed with reclaim brine and water to dissolve carnallite and avoid precipitation of fine decomposition KCl. Wet screening divides solids into fine, middle and coarse fractions. The coarse fraction goes to wet milling and is returned to wet screening; the middle fraction proceeds to rougher flotation; the fine fraction goes to desliming.
Desliming removes fine insoluble material using cyclones. The cyclone overflow, containing most insolubles, is sent to thickening; the underflow proceeds to rougher flotation. Thickener overflow is reused as reclaim brine.
Rougher flotation processes feed containing approximately 20% to 40% KCl in solids (crude salt approximately 25% KCl) and produces a concentrate with over 80% KCl. Concentrate is fed to the cleaner flotation feed cyclone; the underflow goes to cleaner flotation and the overflow to effluent flotation. Rougher tailings are screened; the through fraction goes to tails thickening, while the oversize is crushed and sent to scavenger flotation.
Cleaner flotation enriches KCl to over 90% in solids. Tailings with over 20% KCl are recycled to rougher flotation. Concentrate is leached with water to dissolve NaCl, achieving the designated product purity.
Scavenger flotation recovers KCl from reground rougher tailings, separating KCl from insoluble material. Concentrate is sent to cleaner flotation; tailings are returned to screening.
Effluent flotation treats fine solids from cyclone overflows using column flotation. Approximately one third of the feed solids are KCl. Concentrate goes to leaching; tailings go to tails thickener.
Reclaim brine, a NaCl and KCl saturated solution, is recovered from thickener overflows. A disposal brine stream of 26 m³/h is discharged to control MgCl₂ content below approximately 50 g/l.
KCl product is debrined in centrifuges to 5% residual water, dried, and screened into fine, standard and oversize fractions. The oversize is crushed and returned to the product screen.
Option 2: Solar and Thermal Evaporation of Material from Solution Mining
This option uses solution mining to produce saline brine. Processing includes solar evaporation, thermal evaporation and NaCl crystallization, KCl crystallization, KCl product debrining, drying and screening, and solvent conditioning. The dry KCl product is planned to have a purity of at least 95%.
Brine from solution mining is led to solar evaporation ponds where water is removed and NaCl crystallizes. Brine is separated from NaCl crystals before KCl saturation (approximately 97%) and conveyed to the processing plant. Approximately 0.35 km² of evaporation surface is required for sylvinite mining brine; solar evaporation tests on site are recommended.
Thermal evaporation is performed in a four-stage evaporator system. The first stage is heated with steam; subsequent stages use vapour from preceding stages. NaCl crystallizes during evaporation and is dewatered by centrifuges. KCl brine at approximately 135°C undergoes flash evaporation where additional NaCl crystallizes and is removed.
KCl crystallization occurs via cooling in two sections: a brine-cooled section (four stages) and a water-cooled section (three stages). Crystallized KCl from stages 4 and 7 is dewatered by centrifuges. Mother liquor is largely recycled; approximately 5% is removed to limit MgCl₂ concentration.
KCl product is debrined in centrifuges to 5% residual water, dried, and screened. Solvent for solution mining is conditioned using vapour condensates from thermal evaporation and KCl crystallization stages, supplemented by heated cooling water to approximately 70°C.
Option 3: Solar Evaporation and Flotation of Material from Solution Mining
This option uses solution mining with solar evaporation followed by flotation of the crystallized material. Processing includes solar evaporation, crystallizate treatment, desliming, rougher flotation, cleaner flotation and leaching, scavenger flotation, reclaim brine and brine disposal, effluent flotation, and KCl product debrining, drying and screening. The dry KCl product is planned to have a purity of at least 95%.
Brine from solution mining undergoes two-stage solar evaporation. First, NaCl crystallizes in ponds requiring approximately 0.75 km² of evaporation surface. After brine separation from halite sediment, a second pond stage (approximately 2.25 km²) produces a Sylvite/Halite mixture. The mixture is harvested using surface miners and transported to the plant.
Crystallizate treatment follows the same screening, crushing, repulping and wet screening sequence as Option 1. Fine material goes to desliming, middle fraction to rougher flotation.
Desliming removes fine insoluble material (assumed from dust blown into ponds) using cyclones, with the same process flows as Option 1.
Rougher flotation processes feed containing approximately 20% to 40% KCl in solids (crystallizate approximately 31% KCl) and produces a concentrate with over 80% KCl. Flows are equivalent to Option 1.
Cleaner flotation, scavenger flotation, effluent flotation, and reclaim brine and brine disposal follow the same designs as Option 1, except that surplus reclaim brine is discharged directly as disposal brine without a specified rate.
KCl product debrining, drying and screening follow the same design as Option 1.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Production capacity (all options) | 1 million tonnes KCl/year | Design |
| Annual operating hours (all options) | 7,500 hours/year | Design |
| Plant operating schedule (all options) | 24 hours/day, 7 days/week | Design |
| Dry KCl product purity (all options) | At least 95% | Design |
| Crude salt KCl content (Option 1) | Approximately 25% | Testwork/design |
| Crystallizate KCl content (Option 3) | Approximately 31% | Testwork/design |
| Rougher flotation feed KCl (Options 1 & 3) | 20% to 40% in solids | Design |
| Rougher flotation concentrate KCl (Options 1 & 3) | Over 80% in solids | Design |
| Cleaner flotation concentrate KCl (Options 1 & 3) | Over 90% in solids | Design |
| Cleaner flotation tailings KCl (Options 1 & 3) | Over 20% in solids | Design |
| Residual water in debrined KCl (all options) | 5% in wet solid | Design |
| MgCl₂ limit in circulating brine (Option 1) | Approximately 50 g/l | Design |
| Disposal brine flow (Option 1) | 26 m³/h | Design |
| Solar evaporation surface, sylvinite brine (Option 2) | Approximately 0.35 km² | Preliminary design |
| Solar evaporation surface, NaCl ponds (Option 3) | Approximately 0.75 km² | Preliminary design |
| Solar evaporation surface, Sylvite/Halite ponds (Option 3) | Approximately 2.25 km² | Preliminary design |
| Solvent temperature (Option 2) | Approximately 70°C | Design |
| Thermal evaporation temperature (Option 2) | Approximately 135°C | Design |
| KCl saturation threshold (Options 2 & 3) | Approximately 97% | Design |
Project website: https://www.e-mj.com/news/africa/allana-potash-project-cost-pegged-at-642m/
Technical qualifications
All processing descriptions represent preliminary flowsheet designs developed for a preliminary economic assessment. No actual operating data from the Danakhil deposit are reported. Options 2 and 3 specify that solar evaporation tests on site are recommended to define exact evaporation rates for pond sizing. The report notes that block schemes and mass balances are provided in referenced figures (Figures 19, 20 and 21) which are not included in this text. All product purity and performance values are design targets.
Source: Danakhil Potash Deposit , 2011 Technical Report, Section 17 Recovery Methods, pages 75–88.
2011 Potash PEA Technical Report
This profile describes the proposed processing route for solution-mined sylvinite brine as outlined in the 2011 Preliminary Economic Assessment (PEA) for the Danakhil Potash Deposit, Afar State, Ethiopia. The technical report was prepared for Allana Potash Corporation with an effective date of 30 April 2012.
Report context
The 2011 PEA described a conceptual processing scheme for potash recovery from solution-mined sylvinite and carnallitite. However, only the sylvinite-brine processing route is detailed in the report. No recent test work to verify mining and processing concepts had been completed at the time of reporting. Preparations for pilot cavern operation and evaporation testing, as well as rock mechanical test work, were in progress. Historical information from the PARSONS exploration program indicated that conventionally mined material from the Sylvinite Member could be successfully processed using flotation, but no process details were available from that earlier program.
Processing route
The proposed process for KCl recovery from sylvinite brine uses solar evaporation ponds followed by conventional flotation and product finishing. The route begins with brine produced from solution mining of the sylvinite zone.
Solar evaporation and salt rejection
Brine from sylvinite solution mining is directed to solar evaporation ponds without intermediate storage. In the first pond stage, solar evaporation concentrates the brine while NaCl crystallizes. Halite crystals sediment within the pond. Before the brine reaches approximately 97% KCl saturation, it must be separated from the halite crystals and conveyed to subsequent ponds.
The solid halite sediment is declared as waste. It may remain in the pond if sufficient capacity is available, or be removed and stockpiled temporarily, or directed to cavern backfill.
Sylvite/halite harvesting
The separated brine is led to a second pond stage (Sylvite/Halite ponds), where further solar evaporation causes both NaCl and KCl to crystallize. After complete evaporation, the mixed sylvite/halite salt layer is harvested from the pond using surface miners. Harvested material is loaded directly onto trucks, unloaded near the ponds, and then transported to the processing plant via conveyor belt.
Plant processing
At the plant, the harvested sylvite/halite mixture undergoes:
- Grinding
- Flotation
- KCl product debrining
- KCl washing to achieve required grade
- KCl drying
- Reclaim flotation brine and solid waste (NaCl) disposal
Key reported parameters
| Parameter | Value / Description | Basis |
|---|---|---|
| KCl saturation threshold for brine transfer | ~97% | Design criterion for pond operation |
| Primary waste solid | NaCl (halite) | Conceptual design |
| Harvest method for sylvite/halite mixture | Surface miners, truck loading, conveyor transport to plant | Proposed design |
| Plant unit operations | Grinding, flotation, debrining, washing, drying | Proposed design |
| Waste handling | NaCl disposal; reclaim flotation brine | Proposed design |
| Processing of carnallitite brine | Not described in detail | Study limitation |
| Processing of kainitite brine | Theoretically possible but requires investigation | Study limitation |
Project website: https://en.wikipedia.org/wiki/Potash
Technical qualifications
The processing route described is based on the 2011 PEA and represents a conceptual design, not a tested or operating flowsheet. No recent test work had been completed at the time of reporting, and the process description is limited to sylvinite-brine processing. The report does not provide testwork-derived metallurgical recoveries, product grades, reagent types or dosages, equipment sizing, or pond area requirements. Historical PARSONS flotation results are mentioned but not detailed. The 97% figure refers to the approach to KCl saturation for brine transfer between pond stages, not to product purity or recovery.
Source: Updated Resource Report for the Danakhil Potash Deposit, Afar State/Ethiopia, prepared by ERCOSPLAN Ingenieurgesellschaft Geotechnik und Bergbau mbH for Allana Potash Corporation. Effective date 30 April 2012. Relevant sections: 14 Mineral Processing and Metallurgical Testing; 18 Recovery Method; 18.1 KCl recovery from Sylvinite Brine.
