This feasibility study technical report describes the proposed processing route for the Zinnwald lithium deposit in Germany, based on integrated beneficiation and hydrometallurgical testwork.
Report context
The Zinnwald Lithium Project Technical Report on the Feasibility Study, with an effective date of 31 May 2019, was prepared for Deutsche Lithium GmbH. The report documents a feasibility study for the proposed processing of lithium-bearing ore from the Zinnwald deposit located in Germany. The study presents a complete processing flowsheet from run-of-mine ore through to final product, supported by pilot plant testwork and historical operating data from the region.
Processing route
Summary Flowsheet
The proposed recovery method comprises two main circuits: a beneficiation plant and an extraction and precipitation plant. The beneficiation circuit produces a zinnwaldite concentrate, which is then processed through pyrometallurgical and hydrometallurgical stages to produce lithium fluoride and potassium sulfate (SOP) as final products.
Beneficiation Circuit
The beneficiation process begins with pre-crushing of run-of-mine ore, followed by drying and cooling. The dried material undergoes high-pressure grinding roll (HPGR) grinding and screening. Magnetic separation is then employed to produce a zinnwaldite concentrate. The concentrate and tailings streams are directed to separate storage and loading facilities. A dedusting system is incorporated throughout the beneficiation circuit.
Extraction and Precipitation Circuit
The pyrometallurgical stage involves grinding of the zinnwaldite concentrate, pelletizing the ground material, and then drying, roasting, and cooling the pellets. The roasted product then passes to the hydrometallurgical circuit.
In the hydrometallurgical circuit, the roasted product is milled before entering the leaching stage, where leaching and residual removal occur. The leach solution undergoes purification to remove impurities. Lithium fluoride is precipitated from the purified solution, then dried and packaged as a final product. The remaining solution is processed through SOP-crystallization to produce potassium sulfate, which is dried and packaged separately.
Process Design Criteria and Equipment
The report includes process design criteria that inform the design basis for both the beneficiation and extraction circuits. Equipment selection is documented for all major unit operations in the processing plant. Services for the processing plant include reagent handling, water services, and other supporting utilities.
Historical and Testwork Basis
Historical testwork programs for beneficiation are referenced, alongside feasibility study pilot plant testwork conducted specifically for this project. Variability testwork was also undertaken. The metallurgical testwork program included mineralogical test work covering sample selection, methodology, modal mineralogical composition, mineral intergrowth and liberation, and liberation and recovery analysis. Lithium extraction metallurgical test work was conducted on both pyrometallurgical and hydrometallurgical processing stages.
Key reported parameters
| Parameter | Unit | Basis |
|---|---|---|
| Run-of-mine ore feed | No value reported | Proposed design |
| Zinnwaldite concentrate grade | No value reported | Proposed design |
| Final product – lithium fluoride | No value reported | Proposed design |
| Final product – potassium sulfate (SOP) | No value reported | Proposed design |
| Pre-crushing stage | Design concept | Proposed design |
| Drying and cooling stage | Design concept | Proposed design |
| HPGR grinding and screening stage | Design concept | Proposed design |
| Magnetic separation stage | Design concept | Proposed design |
| Concentrate grinding stage | Design concept | Proposed design |
| Pelletizing stage | Design concept | Proposed design |
| Roasting stage | Design concept | Proposed design |
| Leaching stage | Design concept | Proposed design |
| Impurity removal stage | Design concept | Proposed design |
| Lithium fluoride precipitation stage | Design concept | Proposed design |
| SOP-crystallization stage | Design concept | Proposed design |
| Mineralogical composition | Determined from testwork | Testwork |
| Mineral liberation analysis | Determined from testwork | Testwork |
| Lithium extraction performance | No value reported | Testwork |
| Historical beneficiation testwork | Qualitative | Historical data |
Project website: https://zinnwaldlithium.com/project/
Technical qualifications
The report acknowledges historical test work programs that were conducted for previous investigations of the Zinnwald deposit. The feasibility study pilot plant test work and variability test work were conducted specifically for this study. Mineralogical test work was performed on selected samples to determine modal composition and liberation characteristics. The proposed flowsheet represents a design that has been developed based on the available testwork data, with no full-scale operating data from the proposed configuration available at the time of reporting.
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Source: Zinnwald Lithium Project , Technical Report on the Feasibility Study for the Zinnwald Lithium Project, Germany. Effective date 31 May 2019. Sections 1.8, 13, and 17.
