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.
