Botswana Diamonds PLC announced that it has concluded the processing of two bulk samples taken from the Marsfontein diamond development project in the Limpopo Province of South Africa. The samples comprised 58-tons of fresh high-interest kimberlite and 62-tons of kimberlitic material from one of the residual stockpiles, known as ‘Dump E’.
Highlights:
- 87 macro diamonds were recovered from the fresh kimberlite giving a modelled grade of 50 cpht. (carats per hundred tons)
- 24 macro diamonds were recovered from Dump E giving a modelled grade of 16 cpht.
Grades are quoted at a +1.5 mm screen bottom size cut off
James Campbell, Managing Director, commented: “This bulk sampling campaign, which was carried out with the company’s royalty mining contractor Eurafrican Diamond Corporation, had two objectives. The first was to test the grade of the fresh kimberlite and the second was to confirm the grades of one of the mine dumps. Both were achieved, and proof of the fresh kimberlite grade paves the way for further exploration work on Marsfontein to target potential blows.
“The kimberlite grade is aligned with those achieved at Klipspringer mine and Thorny River, which are both nearby, indicating the considerable extent of the kimberlite dyke system. Options will be investigated on exploitation of the dumps once the nationwide lock down in South Africa is lifted and a sense of normality returns to diamond markets, post the global Covid-19 pandemic crisis.”
Results of the bulk sampling program, including modelled results are illustrated in the table below:
| Source | Sample Size (tons) | No of stones | Carats | Raw Grade (cpht) +1.7mm BCOS | Average stone size cts | Largest stone cts | Modelled Grade (cpht) +1.5mm BCOS | Modelled Grade (cpht) +1.0mm BCOS | ||
| Kimberlite | 58 | 87 | 16.53 | 28.5 | 0.19 | 2.28 | 50 | 53 | ||
| Dump E | 62 | 24 | 6.77 | 10.9 | 0.28 | 1.38 | 16 | 21 | ||
The fresh kimberlite was identified as originating from the M8 dyke system, which extends to the Klipspringer diamond mine c.11 km to the west and the company’s Thorny River project to c.5 km the east. The Dump E material was predominantly a mix of M8 kimberlite and dolerite.
Both samples were treated at Eurafrican Diamond Corporation’s processing facility. They were subjected to primary and secondary crushing, pan plant concentration, grease and x-ray recovery and jigging with a nominal bottom cut-off of +1.7mm. These tailings have been retained for future analyses, as required.
The grade modelling was undertaken by Interlaced Consulting. It assumed a conventional kimberlite processing plant, including a re-crush circuit (to recover more finer diamonds).
Modelled results determined are in line with previous estimates and diamond recoveries from the nearby Klipspringer diamond mine.
Work will re-commence at Marsfontein and Thorny River as soon as Covid-19 restrictions are lifted to enable travel to the work areas.
Source: resourceworld.com