Bannerman Resources Limited is pleased to report further positive results from Phase 3 of the Etango Heap Leach Demonstration Plant Program. The Phase 3 results are similar to or better than the assumptions used in the Etango Definitive Feasibility Study (DFS) and have delivered the clear potential to further reduce operating cost estimates. Phase 3 involved trial leaching of Etango ore in three cribs (2m x 2m x 5m high) and six columns (185mm x 5m high) in a configuration designed to mirror the set-up of a full-scale heap operation.
PHASE 3 HIGHLIGHTS
- Fast leach extraction with high recoveries
Total leach extraction of ~93% from a 90 tonne sample over 22 days for the three cribs and six columns (compared to the DFS projection for a scaled up heap of 87%).
- Low sulphuric acid consumption
On average 13.6 kg/tonne for the three cribs and 14.2 kg/tonne for the six columns (compared with the DFS projection of 17.6 kg/tonne).
- Excellent material properties
Clear and clean leach solution with uniform percolation through the material and integrity of the agglomerate.
- High purity product
No evidence of build-up of deleterious elements occurring during the recycling of leach solution.
- Capability building
Growing metallurgical database now reflects large scale testing of 273 tonnes of material since commencement of the heap leach demonstration plant program in April 2015.
Bannerman's Chief Executive Officer, Brandon Munro, said, "We continue to be greatly encouraged by the results from the heap leach demonstration plant. This latest success further de-risks the Etango process route and adds to the significant body of high quality technical work that underpins the large in-ground resource at Etango. We continue to optimise the DFS with a focus on reducing operating and capital costs. The Phase 3 results give us plenty of scope for revisiting key assumptions such as acid consumption."
PHASE 3 RESULTS
Phase 3 of the Demonstration Plant work program entailed the closed circuit heap leach operation of three cribs (cribs 7, 8 & 9). Leach irrigation was conducted for a total of 22 days in two separate stages in order to simulate the conditions of a commercial heap leach operation. The leach solution collected was designated as the pregnant leach solution and was stored separately to be utilised for the solvent extraction (SX) work, which is part of the pending Phase 4 program.
Integrity of the agglomerates was again clearly evident during the unloading process and no percolation issues were observed. This together with rapid drainage occurring during the curing period suggests that the ore has high hydraulic conductivity (permeability) and low moisture retention.
Leach irrigation was stopped at day 22 and the overall uranium extraction achieved after the drain, rinse and post rinse drain phase was approximately 92.8% (compared with DFS projections for a scaled up heap of 86.9%). See Figure 1.
"Figure 1 - Uranium extraction curves for Phase 3" is available at the following address: http://media3.marketwire.com/docs/1049749e_1.pdf
The rate of acid consumption was in-line with previous testing and averaged 13.6 kg/tonne for the four cribs (compared with DFS projections of 17.6kg/t).
These results are in-line with or better than those obtained in laboratory scale test work performed at similar conditions during the DFS. There was also no evidence of 'channelling' and the agglomerated material retained integrity during the leaching process.
These crib results are considered to be highly significant as the conditions are more representative of the agglomeration, stacking, irrigation and drainage methodology expected during a commercial heap leach operation and as such would provide a more accurate picture of the expected results for the full scale plant.
A report detailing the Phase 3 results is attached to this announcement.
Phase 4 is the next step in the Demonstration Plant work program. This will utilise the Phase 3 pregnant leach solution to confirm the DFS assumptions relating to the solvent extraction circuit. This is planned to be followed by a further program in which a variety of scenarios will be tested to identify opportunities for further cost reductions (Phase 5).
"Figure 2 - Etango Heap Leach Demonstration Plant" is available at the following address: http://media3.marketwire.com/docs/1049749e_2.pdf