South Africa

Black Rock Operation

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Categories

Overview

Mine TypeUnderground
Commodities
  • Manganese
Mining Method
  • Bord-and-pillar
Production Start... Lock
Mine Life2053
ShapshotNchwaning and Gloria mines are collectively Black Rock Mine Operation.

Assmang is ramping up production at the Black Rock Mine to 4.6 million tonnes per annum by F2025.
Related Asset

Owners

SourceSource
CompanyInterestOwnership
African Rainbow Minerals Ltd. 50 % Indirect
Assore Ltd. 50 % Indirect
Assmang Proprietary Ltd. (operator) 100 % Direct
African Rainbow Minerals Ltd. (ARM) owns 50% of Assmang (Pty) Ltd and Assore (Pty) Ltd owns 50%.

Assmang is jointly managed by ARM and Assore. ARM provides the administration and technical services while Assore performs the sales and marketing function.

Deposit type

  • Banded iron formation

Summary:

The manganese ores of the Kalahari Manganese Field are contained within sediments of the Hotazel Formation in the Postmasburg Group of the Griqualand West Sequence, a sub-division of the Proterozoic Transvaal Supergroup. The Griqualand West Sequence comprises a basal dolomite and banded ironstones dominating the Ghaap, Postmasburg and the Olifantshoek Groups. The Postmasburg Group consists of basal basaltic andesites of the Ongeluk lava and banded ironstone and manganese of the Hotazel Formation.

On Belgravia, Santoy and Nchwaning farms the Hotazel Formation and overlying Mapedi shales and Lucknow quartzite sequences have been duplicated by thrusting. The thrusted orebodies were mined from surface at the Kalahari Manganese Field discovery outcrop, the Black Rock Koppie and at two other down dip interconnected Belgravia 1 and Belgravia 2 shafts. Mining reached depths of approximately 200 metres. The manganese resources hosted in the thrusted orebodies are reported, collectively, under Black Rock (Koppie area) orebodies. The average thickness of the HotazelFormation is approximately 75 metres, with the banded iron formation (BIF) hosted manganese orebodies occurring as three stratabound and stratiform units of variable thickness. The lowermost orebody (Seam 1) is of a higher grade in comparison to the topmost orebody (Seam 2). Seam 3, which occurs in between Seams 1 and 2, is thin and uneconomic.

The manganese orebodies exhibit a complex mineralogy and more than 200 ore and gangue mineral species have been identified. Hydrothermal upgrading has resulted in zoning of the orebody adjacent to fault positions in most instances. Distal areas exhibit more original and lowgrade kutnohorite and braunite assemblages, while areas immediately adjacent to faults typically exhibit high-grade hausmannite rich ore. The intermediate areas exhibit mineralogy which includes bixbyite, braunite and jacobsite among a host of other manganese-bearing minerals. Similar zonation also exists in the vertical sense.

At the top and bottom contacts it is common to have high iron (Fe) and low manganese (Mn) contents while the reverse is true towards the centre of the seam. This vertical zoning has given rise to a mining practice where only the 4.0 to 5.0-metre-high centre portion of the seam is being mined.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Production

CommodityUnits202320222020201920182017
Manganese Mt 000000003.73.1
All production numbers are expressed as lump & fines. ^ Guidance / Forecast.

Operational metrics

Metrics202320222021202020192018
Ore tonnes mined 0000000000000004.12 Mt
Waste 000000163,443 t

Production Costs

CommodityUnits202320222021202020192018
Site cash costs (produced) Manganese ZAR 000 000 000 000 605 / t   525 / t  

Financials

Units2023202220212020201920182017
Capital expenditures M ZAR  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 1,240   1,671  
Revenue M ZAR  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 10,495   8,322  
Operating Income M ZAR  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 4,478   3,351  
EBITDA M ZAR  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 5,015   3,759  

Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
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Total WorkforceYear
Subscription required 2023
Subscription required 2022
Subscription required 2021
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Subscription required 2019
Subscription required 2018
Subscription required 2017

Aerial view:

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