Braúna mine
The Braúna mine is the first diamond mine in South America developed on a kimberlite deposit, the primary source rock of natural diamonds. The mine is located in the Municipality of Nordestina, a city situated in the interior of the State of Bahia, 350 kilometres to the northwest of the city of Salvador.
The mine has been developed on the Braúna 3 kimberlite, one of 22 kimberlite occurrences that have been discovered on Lipari’s mineral rights holdings. Commercial production commenced in July 2016. As of 31 December 2021, the Braúna mine has achieved sales of US$174 million from 926.447 carats at an average unit sales price of US$188 per carat. The mine itself lies within a mining permit encompassing 1,875 hectares. Lipari also holds 100% of the rights to 4 adjacent mineral licenses covering 5,053 hectares. The Braúna mine entered into commercial production in July 2016 at a capital cost of approximately US$61 million. The mine produces approximately 130,000 carats per year at an average realized sales value of US$190 per carat. The direct cost of production is US$130 per carat or US$21.50 per tonne of ore processed.
The mine is a 12,000-tonne per day open pit mine operation, transporting 2,500 tonnes per day of kimberlite ore to the processing plant. The mine operates with an owner-operated mining fleet with its own maintenance team and facilities. The open pit is currently operating at a depth of 220 metres below the surface and has an ultimate pit design depth of 260 metres below the surface.
Lipari is currently advancing an operational plan to transition the open pit mine to a vertical mining operation which advances the development of the kimberlite to a depth of 360 metres below the surface.
The kimberlite ore mined from the open pit is processed through a 2,500 tonne per day processing plant which operates on a 24 x 7 basis. The plant consists of a crushing and screening circuit which feeds a 150 tonne per hour dense media concentrating circuit, feeding 6 X-Ray diamond recovery machines enclosed in a high-security final recovery building. The plant also has an integrated large diamond circuit featuring XRT technology. Lipari’s in-house plant maintenance team has produced exceptional plant performance with a plant availability averaging over 95%.
Lipari’s processing plant at the Braúna mine recycles 98% of the water used to process the ore. This is done by dewatering the plant “tailings”, which is the waste produced that is produced during the crushing, screening, and concentration of the ore, by passing this fine waste material through a rotary centrifuge which spins the material at a high velocity to remove the water. This clean water is then recycled back to the processing circuit. In addition to water conservation, another important benefit of Lipari’s water recovery system is that the mine does not have a traditional “tailings pond”, or a wet storage system for the processing plant waste. Traditional tailings ponds can be a long-term environmental liability for mining companies and the communities in which they operate. Lipari is extremely proud of the fact that
the mine recycles over 98% of the water used by the processing plant. Lipari is the only diamond producer in the world that operates without a traditional tailings pond.
Lipari is the only diamond producer in the world to use this tailings dewatering system.
For more information, access lipari.com.br
Tchitengo Diamond Project
The Tchitengo Project is situated in the Lunda Province in northeastern Angola, 945 kilometres from the capital city Luanda. The Property encompasses 18 kimberlites including the Tchiuzo and Tchegi kimberlites – two advanced-stage kimberlite deposits. Tchitengo is located in the heart of Angola’s diamond rush:
- 30 km away from Sociedade Mineira de Catoca (SMC) world-class Luaxe kimberlite currently under construction (3-4Mct/annum production starting in 2023);
- 15 km north of the Chiri kimberlite which will be developed by Rio Tinto (US$14M to be invested in 2022);
- 15 km north of the Catoca Mine, Angola’s largest diamond producer at 7.5Mcts/annum; and
- 5km south of the Camatchia mine which produces ~100kcts/annum.
The Property encompasses 30 kimberlites. ALROSA, through its Angolan subsidiary Catoca Mines, explored the southern part of the Tchitengo property and discovered the 10.6-hectare Tchiuzo kimberlite, investing US$32 million between 2006 and 2013. During the same period, a joint venture between BHP Billiton and Banco Espírito Santo explored the northern part of the area and discovered 29 occurrences of kimberlite between 2006 and 2011, investing US$ 25 million in exploration within the concession area.
Tchiuzo Kimberlite
- The 10.6-hectare Tchiuzo kimberlite is the most advanced stage deposit on the Property. SMC developed the kimberlite to the pre-feasibility stage of development. In 2009 SMC reported resources for the Tchiuzo kimberlite, stated to NAEN standards which has been summarized by SRK Consulting (Canada) Inc. as follows:
| Resource Block Designation (Russian Classification) | NI43-101 Equivalent Resource Category | Bench Elevation(masl) | Rock Volume(m3) | SG(cm/m3) | Ore Resource(t) | Resource Grade(cpht) | Diamond Resource(cts) | |
|---|---|---|---|---|---|---|---|---|
| From | To | |||||||
| BLOCK 1 – C1 | Measured Resource | 890 | 880 | 881,847 | 1.76 | 1,552,050 | 45.3 | 703,079 |
| BLOCK 2 – C1 | Measured Resource | 880 | 680 | 8,062,763 | 2.20 | 17,738,080 | 34.5 | 6,119,638 |
| BLOCK 3 – C1 | Measured Resource | 880 | 680 | 7,347,009 | 2.29 | 16,824,650 | 47.9 | 8,059,007 |
| TOTAL – C1 | Measured Resource | 880 | 680 | 16,291,619 | 2.22 | 36,114,780 | 41.2 | 14,881,724 |
| BLOCK 4 – C2 | Indicated Resource | 680 | 530 | 7,492,005 | 2.33 | 17,456,370 | 41.0 | 7,157,112 |
| TOTAL – C1 + C2 | Measured + Indicated | 890 | 530 | 23,783,624 | 2.25 | 53,571,150 | 41.1 | 22,038,835 |
SMC completed the initial pre-feasibility study in 2009 and then updated the study in 2013. The study projected four different open-pit mining scenarios based on ore mining and processing rates ranging from 2.0 MTPA to 2.9 MTPA, and open pit mine depths ranging from 200 metres below surface to 250 metres below surface. Life of mine of these mine scenarios ranged from 13 to 22 years. Diamond sales prices used in their 2013 pre-feasibility study ranged from US$112 per carat to US$149 per carat.
| Reference | Unit | Scenario 1 | Scenario 2 | Scenario 3 | Scenario 4 |
|---|---|---|---|---|---|
| Throughput per annum | MTPA | 2.0 | 2.0 | 2.9 | 2.9 |
| Ore volume for LOM | Million tons | 42.23 | 35.81 | 42.23 | 35.81 |
| Overburden for LOM | Million m3 | 32.56 | 27.13 | 32.56 | 27.13 |
| Head feed for LOM | Million m3 | 51.48 | 43.30 | 51.48 | 43.30 |
| Ore transport for LOM | Million ton/km | 380.56 | 305.85 | 377.10 | 303.35 |
| Commercial Production | Million carats | 17.78 | 15.10 | 17.78 | 15.10 |
| Diamond value | US$/carat | 144.79 | 129.71 | 122.42 | 112.59 |
| Total revenues | US$ million | 2,574.11 | 1,958.48 | 2,176.36 | 1,699.93 |
| Operating expenses | US$ million | 1,310.38 | 1,081.50 | 1,199.93 | 1,007.66 |
| Capital expenses | US$ million | 173,743.00 | 171,568.00 | 195,523.00 | 190,88.00 |
| Return on Capital (IRR) | % | 15.25 | 14.57 | 19.24 | 18.48 |
Tchegi-38 Kimberlite
The Tchegi-38 kimberlite was one of 18 kimberlites discovered by the BHP Billiton/ESCOM joint venture within the boundaries of the Tchitengo Property. BHP Billiton advanced the Tchegi-38 kimberlite to the resource definition stage of development, completing 18 large diameter drill holes which resulted in the recovery of 834 tonnes of kimberlite for processing.
| # LLD Holes Drilled | Metres Drilled | Sample Weight (tonnes) | Diamonds Recovered | Total Weight of Diamonds (carats) | Recovered Diamond Grade (cpht) | Largest Diamond Recovered (carats) | Average Diamond Size (carats/ stone) |
|---|---|---|---|---|---|---|---|
| 18 | 2999 | 834.32 | 2516 | 214.69 | 25.7 | 3.43 | 0.09 |
The central portion of the 10 ha Tchegi-38 kimberlite comprises an open-ended ore body that is well constrained by large diameter drilling. Processing of the 834 tonnes of kimberlite recovered from the drilling program resulted in the recovery of 214.69 carats of diamonds, resulting in a recovered diamond grade of 24.7 cpht. Additional drilling is required to define the margins of the Tchegi-38 kimberlite, and large scale bulk sampling is required to confirm the diamond grade and value.