A few points to consider for DSO....
1. Is there much in the way of shallow resource & at high enough grade?
• 600m of fluorite reef not tested on A,C,E reef.
• Narbarloo Nth Reef constitutes a target equivalent to A,C,E reefs.
• Includes a Recommendation to carry out drilling on Reef A,C to depths of 60M & Reef E to depths approaching 150M
• Should a successful drilling programme be completed then detailed exploration / drilling over the rest of the mineral field is recommended.
• Across Reef A - 7 holes for 198m. Reef C 8 Holes for 209M. Reef E 21 holes for 624M - so they were shallow holes 36 in total for 1031M.
• Reef E Samples returned some high results - 71% 5.8M width, 67.4% 5.9M width, 66.5% 11.1M width, 87.8% 1.3M, 79.6% 4.3M, 81.1% 2.7M etc
- So it's understandable why Reef E should be a drilling target - these results are consistent with the rock chip results from TVN's sampling.
250,000 short tons, 226,796 metric tonnes at 37% inferred at shallow depth less than 30 metres - Dig, crush, ship above ground operation.
• Additional drilling on Reef E - 7 holes for 665 metres - so these were 3x deeper on average than the earlier program. Deepest was 452 feet 137M.
• Calculated 364,000 short tonnes at 39.66% 330kt metric.
• Mineralization to 330 feet or about 100M can be expected to be equivalent in grade to surface grade (important) but disappeared at 450 feet.
• Northern extensions were not drilled - there is opportunity proving substantial additional fluorite in Reef E & the many adjoining reefs.
• Assay Results for this deeper drilling program - 43.5%, 41.1%, 52.5%, 49.2%, 35.8%, 44%
• Hand Samples from page 17 - 90%, 85%, 85-90%, 80-85%, 98%, 90%, 65%, 95%, 60%, 95%, 99%, 75%, 97% - ie consistent with TVN results
• One hole they published in this report shows 86.9% through 66.4% from 71.3-81.3 feet - 3M or there abouts 3.9M width. Moves around a bit but at 91.3 feet is at 75% CaF2 - so decent grade & width at fairly shallow depth.
Logistics -
Co-ordinates 135' 47°E, 22° 42'S - it's here :
https://maps.app.goo.gl/dF9E8FtbJGoV7Hvo6Distance by Air 225km, by Road in 1972 to the deposit was 280km NE from Alice Springs
In 1972 cost to transport concentrate was estimated at ~$46 a short ton to Port Pirie from Alice Springs - noted that Port Pirie & Darwin Ports are listed as each 1,530km from the site - using Google Maps - to Darwin 1,705km, to Port Pirie 1,661km
From Avenira DSO FS - shipping Phosphate from Tennant Creek Area to Port of Darwin via Road/Rail - 30km access road to Barkly Hwy, 284km to Tennant Creek, 875km to Darwin on the rail line.
For processing ~320ktp month (4.2MT over 14 months) equipment recommended & leased/via contractor :
• 3 Excavators, 4 x 90T dump trucks, 1 drill rig (blast holes), General civil machinery for road, grading, water trucks etc.
• Camp for 24 people.
Table 9.1 show operating costs & includes an AISC of $181.3 AUD per tonne sold. Haulage (road Rail) $77.2 p/t, Shipping $15.2p/t.
Table 1 shows Capital Cost breakdown for a total of $11.5M AUD - Mine Security Deposit at $2.9M, Pre-Strip Mining costs $5.8M, the rest is mobilisation costs & contingencies.
Processing - This was a bit of a question for Chat GPT - what process circuits are needed :
For upgrading from 20% CaF₂ to 80% CaF₂:
Crushing Circuit
rimary Crusher, Secondary Crusher, Tertiary Crusher (if needed)
Grinding Circuit:Ball Mill or Rod Mill (to achieve fine particle size)
Flotation Circuit:Conditioning Tanks, Flotation Cells, Reagent Dosing Systems,
Thickeners and Clarifiers:To concentrate the slurry
Drying Equipment:Rotary Dryers or Fluid Bed Dryers
Vs
For upgrading from 40% CaF₂ to 85% CaF₂
Crushing Circuit
rimary Crusher, Secondary Crusher (if needed)
XRT Sorting:XRT Sorting Machine (to separate based on density)
Minimal Drying Equipment:Optional, depending on moisture content
Enviro approvals - this was the bug bear of days past, so without revisiting this, NTEPA EIS is only required if a self assessment determines the proposal has the potential to have significant impact on the environment.
The Pre-referral screening tool is available
at this link starting at page 31 & in Appendix 1.
See the FAQ page 4.
Based on the above -
Shallow mining program across Reefs A,C,E to 30M inferred resource at 226kt 40% - noting a more comprehensive drill mapping program will prove out the better bands of mineralization in order to target these for DSO - the hole from Reef E with a band at 86.9% to 75% 3M deep from 71 feet with 3.9M width.
Now that I've done all the above, I think the only way to make sense of it is to make a few estimates - based on different grades.
Too complex for a Saturday night.
BBL
