Overview

Mine Type	Underground
Status	Active
Commodities	Gold
Mining Method	Blast Hole Stoping Conventional narrow-reef mining
Production Start	...
Mine Life	...
Snapshot	Blyvoor Mine, is a producing, high-grade, long-life underground gold mine in the Witwatersrand region near Johannesburg, South Africa, one of the most prolific regions for gold production in the world. Formerly known as Doornfontein No 3 Shaft, the mine has outlasted several owners. It acquired its name Blyvoor in 1997. Aurous restarted production from the Blyvoor Mine in 2022. Aurous intends to ramp up Blyvoor Mine gold production to average ~150 koz per year at an all-in-sustaining cost of ~$815/oz with further upside from Gauta Tailings.

Deposit type

• Conglomerate hosted

Summary:

Gold and uranium deposits in the Witwatersrand Basin are hosted by quartz-pebble conglomerates, which are generally less than 2 m in thickness and developed on laterally continuous unconformity surfaces. These reefs are generally characterised by shallow dips of between 10° to 25° and thicknesses of 1.0 m to 2.5 m that make them suitable for exploitation by means of typical narrow stoping techniques.

The gold deposits of the Witwatersrand Basin are considered to be associated with coalesced fluvial braidplains, where gold was concentrated within braided stream gravels developed on unconformities which have been correlated around the basin.

Most early theories on the origin of gold believed the gold to be deposited syngenetically (placer theory) with the conglomerates or by epigenetic means (hydrothermal origin), but subsequent research by Kirk et al (2004) concluded that metamorphism caused the post depositional local redistribution of gold (modified placer theory).

Generally, gold occurs in native form often associated with pyrite (less commonly pyrrhotite) and carbon, with quartz as the main gangue mineral.

At Blyvoor, two economic placer horizons have been exploited. These are namely the Carbon Leader and Middelvlei Reefs and occur in quartzites of the Main Reef Conglomerate Formation of the Johannesburg Subgroup of the Central Rand Group. The auriferous conglomerates dip uniformly at 22°S.

The Carbon Leader is a high grade, predominantly thin (<40 cm) carbon-rich reef and is the principle economic horizon at Blyvoor. The origin of the carbon is in debate as to whether it originated hydrothermally or from algae. Within the deeper southern section of the Mine, carbon is scarcer and hence likely responsible for the decline in grade.

In the western area, the Carbon Leader is eliminated by a northwest-southeast striking, 1,900 m wide erosional channel. The erosion channel is truncated to the north by the Master Bedding Fault. Its eastern boundary is well defined by mining, while the western boundary is less certain and has only been defined by drilling.

The Carbon Leader is divided into seven facies areas, namely F1 to F7, based on channel width and carbon content. Four types of Carbon Leader are recognised:-
• carbon seam;
• channel reef;
• thin single reef; and
• thick single reef.

Grade generally decreases down dip (south) and towards the west associated with a reduction in carbon.

The Middelvlei Reef is the second economic horizon at Blyvoor and lies stratigraphically 50 m to 75 m above the Carbon Leader. Towards the south, the separation increases due to a minor angular unconformity. The Middelvlei Reef is characterised by lower grades than the Carbon Leader. Owing to the variable payability and presence of sedimentologically controlled pay shoots, the Middelvlei Reef has been mined in scattered payable areas and is present over the whole lease area.

On the Middelvlei Reef, facies areas have similarly been identified using grade, channel direction and reef characteristics.

Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

Commodity	Units	2023
Gold	koz	....

Personnel

Job Title	Name	Profile	Ref. Date
.......................	.......................		Nov 14, 2024
.......................	.......................		Nov 14, 2024
.......................	.......................		Mar 1, 2021

Employees	Year
......	2023