Overview
Stage | Production |
Mine Type | Open Pit / Underground |
Commodities |
|
Mining Method |
- Truck & Shovel / Loader
- Longhole open stoping
- Cemented backfill
|
Processing |
- Gravity separation
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 9 years (as of Jan 1, 2017) |
The mine is a combined open pit and underground operation from two deposits, Gokona (underground) and Nyabirama (open pit). |
Latest News | Barrick Gold Corporation: Twiga a Triumph of Partnership October 23, 2020 |
Source:
p. 176
Company | Interest | Ownership |
Government of Tanzania
|
16 %
|
Indirect
|
Barrick Gold Corp.
|
84 %
|
Indirect
|
Twiga Minerals Corporation Ltd.
(operator)
|
100 %
|
Direct
|
On January 24, 2020, Barrick announced that the Company had ratified the creation of Twiga Minerals Corporation at a signing ceremony with the President of Tanzania, formalizing the establishment of a joint venture between Barrick and the GoT and resolution of all outstanding disputes between Barrick and the GoT, including the lifting of the previous concentrate export ban, effective immediately. The GoT will receive a free carried shareholding of 16% in each of the former Acacia mines (Bulyanhulu, Buzwagi and North Mara), and will receive its half of the economic benefits from taxes, royalties, clearing fees and participation in all cash distributions made by the mines and Twiga, after the recoupment of capital investments. Twiga will provide management services to the mines.
Summary:
The North Mara Mine is situated within the Mara Greenstone Belt. The underlying geology comprises felsic and mafic volcanics intercalated with sediments which are intruded by various granitoid and gabbroic plutonic rocks. Tertiary volcanic lava flows partially cover the underlying Archaean geology and the ore bodies are structurally controlled, shear-hosted lode gold deposits. There are several types of gold mineralisation including shear-zone-related quartz vein and disseminated gold.
Mining Methods
- Truck & Shovel / Loader
- Longhole open stoping
- Cemented backfill
Summary:
The mine is a combined open pit and underground operation from two deposits, Gokona (underground) and Nyabirama (open pit).
At Gokona, Acacia utilizes an existing exploration decline for initial access to the planned underground mine. Two major declines are included in the mine plan.
The mining method utilised in the operation is Long Hole Open Stoping (“LHOS”) with Cemented Aggregate Fill (“CAF”).
Processing
- Gravity separation
- Concentrate leach
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Source:
Summary:
Both oxide and sulphide reserves are mined and processed by conventional carbon-in-leach (CIL) technology.
The ore is hauled in 80 tonne dump trucks up to the Run of Mine (ROM) pad at Nyabirama. The ore is drawn out of the ROM bin and fed onto a vibrating grizzly screen by means of an apron feeder. The undersize material passes through the grizzly onto a conveyor belt while the oversize material passes through a jaw crusher which discharges onto the same conveyor belt. The ore is fed onto a banana screen via a two tier conveyor system. The undersize from the banana screen passes onto a conveyor belt which feeds the SAG mill feed stock pile while the oversize material is fed into a secondary cone crusher. The crushed ore from the secondary stockpile is tipped onto the SAG feed stockpile.
The ore is drawn from underneath the SAG mill feed stockpile onto the SAG mill feed conveyor belt by means of three vibrating feeders. It is fed into the SAG mill for primary g ........

Recoveries & Grades:
Commodity | Parameter | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2013 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  | ......  | ......  | ......  | ......  |
Gold
|
Head Grade, g/t
| 4.5 | 4 | 3.9 | 4.5 | 3.6 | 3.5 | 3.5 |
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Reserves at December 31, 2019:
Category | OreType | Tonnage | Commodity | Grade | Contained Metal |
Proven & Probable
|
In-Situ (OP)
|
17.86 Mt
|
Gold
|
1.49 g/t
|
0.87 M oz
|
Proven & Probable
|
In-Situ (UG)
|
6.9 Mt
|
Gold
|
5.4 g/t
|
1.19 M oz
|
Proven & Probable
|
Total
|
25 Mt
|
Gold
|
2.57 g/t
|
2.02 M oz
|
Measured
|
In-Situ (OP)
|
2.74 Mt
|
Gold
|
2.37 g/t
|
0.21 M oz
|
Measured
|
In-Situ (UG)
|
0.88 Mt
|
Gold
|
6.13 g/t
|
0.18 M oz
|
Measured
|
Total
|
3.69 Mt
|
Gold
|
3.28 g/t
|
0.38 M oz
|
Indicated
|
In-Situ (OP)
|
32.14 Mt
|
Gold
|
1.73 g/t
|
1.79 M oz
|
Indicated
|
In-Situ (UG)
|
11.9 Mt
|
Gold
|
4.57 g/t
|
1.79 M oz
|
Indicated
|
Total
|
44.07 Mt
|
Gold
|
2.52 g/t
|
3.57 M oz
|
Inferred
|
In-Situ (OP)
|
2.14 Mt
|
Gold
|
1.1 g/t
|
0.071 M oz
|
Inferred
|
In-Situ (UG)
|
7.5 Mt
|
Gold
|
4.5 g/t
|
1.083 M oz
|
Inferred
|
Total
|
9.64 Mt
|
Gold
|
3.7 g/t
|
1.155 M oz
|
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