Exploration and projects within AngloGold Ashanti focus on creating significant value for the company by providing long-term optionality and improving the portfolio quality, two of our strategic focus areas. Our exploration programme covers greenfields and brownfields projects.
These strategic objectives are met by:
- Greenfields exploration which aims to discover large, high-value Mineral Resource, which will eventually lead to the development of new gold mines
- Brownfields exploration focuses on delivering value through accretive additions to the Ore Reserve at existing mines as well as new discoveries in defined areas around operations. Brownfields exploration actively drives the creation of value by growing our Mineral Resource and Ore Reserve, our major assets. The brownfields exploration programme is based on innovation in geological modelling and mine planning, and continual optimisation of our asset portfolio
This report serves to highlight the achievements in 2019. In 2020, the focus will fall on increasing the Ore Reserve by increased Ore Reserve development and exploration drilling, primarily in Brazil and Australia.
Exploration was conducted within 5,500km2 of highly prospective ground in two countries – Australia and the United States – along with licence applications and other ground positions in Argentina, Brazil and Tanzania. In total, more than 71km of diamond, reverse circulation (RC) and aircore (AC) drilling was completed in 2019.
In Australia, in the Laverton district, AngloGold Ashanti completed the 70% earn-in at the Butcher Well and Lake Carey JV. The Butcher Well scoping study was updated by integrating the drilling results from the second half of 2018. Elsewhere in Laverton, a total of 49,200m of aircore drilling and 4,486m of diamond drilling was completed on several joint venture and non-joint venture projects.
Diamond drilling programmes were also completed at the Mt Clark prospect in North Queensland (nine holes for 2,748m) and the Glandore prospect, located 60km east of Kalgoorlie in Western Australia (six holes for 1,846m), with no positive results derived.
In the United States, at the Silicon project in Nevada, 8,008m of RC and 3,300m of diamond drilling were completed in 2019. The programme followed up on and further developed understanding of the alteration system intersected in earlier drilling as well as testing other favourable litho-structural targets within the Silicon- Thompson structural corridor. An induced polarization (IP) survey was also completed along with ground magnetic and gravity surveys. The second-year anniversary payment was made to Renaissance Gold during the period to maintain the option earn-in agreement into the third and final year in 2020.
Also in the United States, in Minnesota, roto-sonic drilling was completed over several target areas with 54 holes completed for a total of 1,619m. Since the results from the programme were not encouraging, work has stopped. AngloGold Ashanti returned all the mineral leases to the state of Minnesota.
In Argentina and Tanzania, exploration properties are on care and maintenance. Target generation activities were completed in Brazil and West Africa.
Brownfields exploration was carried out in 9 countries, in and around AngloGold Ashanti operations. A total of 877,630m of Diamond and RC drilling was completed during the year.
Exploration continued with one-hole drilled at Mponeng’s Western Ultra Deep Levels targeting the Ventersdorp Contact Reef. Drilling was stopped due to capital constraints and the final site clearance/ closure certificate signed off in June.
Argentina: At Cerro Vanguardia, due to budget constraints, exploration was focused on mapping, surface sampling and ground geophysical surveys.
Brazil: At AGA Mineração, in the Iron Quadrangle, a total of 263,345m was drilled. At Cuiabá, the underground drilling programme focused on Fonte Grande and Serrotinho (upright limb), Balancão and Galinheiro (overturned limb). A long-inclined borehole drilling project was successfully completed. Positive results with significant intercepts were reported for secondary targets including the quartz vein project (VQZ) and Viana.
Regionally, drilling at the Descoberto target is ongoing and has produced encouraging observations. Land access was granted in October 2019 to allow the Matarelli target drill programme to begin. A trial unmanned aerial vehicle (UAV) magnetic survey was successfully completed at Matarelli and a more comprehensive survey covering the Matarelli and Tinguá targets is planned. A detailed geological map and associated cross sections were produced over the Tinguá target area ahead of a geochemical soil programme planned for early 2020.
At Lamego, drilling focused on confirming the continuity of Carruagem in a south-westerly direction (both limbs) from levels 1 to 5. Drilling also took place at Cabeça de Pedra (hinge zone), which reported high grades and indicated that the orebody remains open. Drilling at CdS tested the Rosalino open pit. At CdS I, underground drilling in Laranjeiras and Carvoaria confirmed the Mineral Resource and indicate good prospectivity for high grades in Carvoaria. In the ‘Gold Quadrangle’ area of Candeias-Cristina, Mutuca, Cachorro Bravo and Pneu, drilling supported Mineral Resource additions in the area.
At CdS II, drilling in the shallow north-east portion of São Bento confirmed the continuity of the mineralised structure in that direction. The Remaining Ounces project identified potential areas for high-grade ore within old mining areas. At CdS III, a sterilisation drilling campaign is underway and one positive intercept suggests the extension of the Anomalia and Jambeiro target trends.
A total of 128,888m was drilled at Serra Grande. Exploration drilling at Pitanga, Palmeiras South, Mangaba, Corpo IV, V and Limoeiro resulted in the addition of Mineral Resource. The mine acquired the Palmeiras South area in late 2018 which contains the southern extension of all mineralised trends; subsequent drilling during 2019 returned positive results along Structure 3.5.
The Pitanga orebody was discovered along Structure III close to Mina Nova mine. Reinterpretation of existing orebodies at Corpo IV, Corpo V and Limoeiro, supported exploration drilling and lead to new ounce generation. Target generation focused on assessing shallow opportunities and using interpreted S2 stacking behaviour to identify new potential areas to test in 2020.
Colombia: Limited exploration activities were completed at Gramalote. RC drilling started at Trinidad in October and diamond drilling at Gramalote in November with no results reported to date.
The La Colosa project continued on care and maintenance following the cessation of all field activities in April 2017.
At Quebradona, a total of 10,494m was drilled, focusing on geotechnical programmes for site infrastructure, the tunnel trace, the mine subsidence area and the crusher chamber. Geological and structural models were updated for infrastructure sites, the tunnel and mine area.
Tanzania: At Geita, a total of 96,407m of drilling was completed in 2019.
The overall results for Star & Comet Cut 2 Mineral Resource drilling were positive. While exploratory drilling results identified no economic intersections, interpretation and review are ongoing. The Star & Comet Cut 3 Mineral Resource drilling results confirmed the down-dip continuity. Extension drilling at Star & Comet Cut 2 and Cut 3 confirmed the presence of open-ended high-grade mineralisation along the hanging wall and footwall sides of the intrusive, suggesting that the Cut 2 and Cut 3 orebodies might join and become one.
Mineral Resource development drilling programmes for Nyankanga underground were carried out at Blocks 3, 4 and 5 as well as in the gap area between Block 2 and 3. All results were positive.
Three of eight holes in the surface drilling programme at the Star & Comet North Extension returned lower grades than previous data. Results from surface drilling completed at Selous confirmed the orebody extensions inside and outside the pit margins. While exploratory surface drilling at Mabe delineated localised orezones of medium to high grade.
At Geita Hill, underground Blocks 1 and 2 drilling results defined low-grade mineralised zones. Drilling initiated at the Roberts deposit confirmed the presence and potential of economic ore zones within and outside the optimised pit.
Guinea: At Siguiri, a total of 74,939m was drilled during the year.
Kami drilling has shown that the mineralisation extends into the fresh rock and into oxide in Kami East saddle. Bidini drilling shown that the mineralisation extends to the east of the pit in oxide.
Silakoro West drilling was completed and confirmed the mineralisation. While at Silakoro North drilling intersected mineralisation associated with disseminated sulphides.
Foulata East drilling results show unmineralised albitite, while the main Foulata drillholes indicate the potential extension of mineralisation at depth and along the trend. Advanced grade control (AGC) drilling at Foulata confirmed the model.
At Saraya, drilling confirmed the extension of shallow mineralisation to the north and deeper along the plunge. The Saraya AGC drilling confirmed the model despite defining thicker internal waste intervals. At Seguelen, PB2 drilling confirmed the extension of the mineralisation in the fresh rock.
The Sanu Tinti infill drilling crossed potentially mineralised breccioconglomerates layers. At Niono, reconnaissance drilling showed weak potential for oxide mineralisation. The Doko, Block 4, reconnaissance drill programme is now 48% complete with some economic intersection.
At Balato North, Saraya West EL and Setiguiya West reconnaissance drilling showed negative results. Field visits and reviews confirmed the potential of the Carbonate Hills (East and Central) targets.
Ghana: At Iduapriem, a total of 21,279m was drilled in 2019. Exploration focused on Mineral Resource conversion drilling at Block 1, Ajopa, Efuanta and Block 4S. Regional mapping of the hydrothermal targets commenced during the year as well as auger drilling at Mile 8 and Mile 5W targets.
At Obuasi, drilling started on 27 May 2019 with capital drilling on 41 level, grade control drilling on 17 and 22 levels, and expensed exploratory drilling in the GCS top area.
The 41-level drill programme completed 7,921m of combined RC and diamond drilling. Two multi-purpose RC/diamond rigs are being used to accelerate data acquisition and reduce costs. The grade control programme drilled 3,480m and showed continuity of the Obuasi fissure in terms of grade and structure. The 5,475m of exploratory drilling indicated potential in the footwall splays.
DRC: A total of 25,210m was drilled at Kibali.
The drilling results at Gorumbwa-Sessenge gap support the continuity of the mineralisation from Gorumbwa into the gap.
At Ikamva, drilling observations support the model while at Ikamva- East, the drilling programme was completed, and the results returned support the consistency of the two lenses. Two holes were drilled into the Kalimva-Ikamva Hinge zone with results supporting the model of a potential link between the two structures.
Results also suggest the presence of other shoots pertaining to the Kalimva system.
The orientation drilling programme along the Zakitoko-Birindi trend was completed and indicate an extension down dip and along strike. A data review of the Aindi area was conducted leading to identification of four zones of interest.
In the Oere-Kalimva Gap, the drilling programme is complete and indicates no mineralisation within the gap. While in the Mofu-Oere gap, a trenching programme showed weak results from surface that increase down dip and plunge.
Eight trenches were excavated in the Mandungu-Memekazi-Renzi trend with overall results supporting the model and the trenching programme at Memekazi Northeast, returning results that support the potential of the area.
At Sayi, the results support the model and continuity of the interpreted mineralisation. While drilling in the Sayi-Mengu gap returned narrow intercepts. Results from the Renzi trenching programme support the model, though they are relatively low grade, while the Oere drilling results support the presence of highgrade domains within the mineralisation envelope.
A soil sampling programme in the KZ South area returned results supporting potential for a mineralised system. At Pakaka, drilling results from the hole furthest southeast support a consistently thin high-grade mineralisation along the sheared contact observed in the pit.
Mali: No drilling was completed in 2019.
Australia: At Sunrise Dam, six underground rigs were in use during the period, with most drilling taking place at Vogue, Midway Shear (MWS) Steeps and Elle, as well as at Stella (Target 18) and Steeps below Sunrise Shear Zone (Target 01). Commissioning of a seventh underground rig took place during November and an eighth rig was commissioned in December 2019.
One surface rig was in operation, targeting the southern extensions of the deposit from surface, 520m and 360m south of the current Ore Reserve from the Cleo waste dump.
At Tropicana, mine drilling consisted of infill drilling at Havana to upgrade the Mineral Resource confidence and assist in the mining option studies. Significant results were returned from the infill drilling at Havana, as well as encouraging results from drilling at Havana South down-dip.
Regional drilling was concentrated at Iceberg, Tumbleweed, New Zebra, Angel Eyes Voodoo Child, Wild Thing, Electra, Mojito and Monsoon. Regional drilling produced an important result from RC drilling at Voodoo Child that indicates mineralisation is present ~500m along strike from the defined prospect.
The greenfields projects in Colombia make a significant contribution to AngloGold Ashanti’s Mineral Resource with the three projects, La Colosa, Quebradona and Gramalote, collectively contributing 38.5Moz. Quebradona and Gramalote contribute 4.3Moz to the gold Ore Reserve. Quebradona also has a copper Ore Reserve of 3,068Mlbs. Both Quebradona and Gramalote are at various stages of feasibility study while the La Colosa project is currently under force majeure, pending the necessary environmental permits.
The Gramalote project, a joint venture between AngloGold Ashanti (51%) and B2Gold (49%) in Colombia, lies on the eastern flank of the Cordillera Central, near the towns of Providencia and San Jose del Nus in the municipality of San Roque, in the north-west of the Antioquia Department. It is approximately 230km north-west of Bogota and about 120km north-east of Medellin.
In September 2019, AngloGold Ashanti announced that an agreement had been reached with B2Gold, in terms of which B2Gold would fund an investment and exploration programme in 2020 to the value of $13.9m, in order to earn back to a 50:50 partnership and assume management of the project effective 1 January 2020. Completion of the feasibility study for Gramalote is targeted for the end of 2020. The project has several key infrastructure advantages including reliable water supply, its close proximity to key infrastructure and a technically capable workforce in country.
As per the agreement, B2Gold assumed management of the Gramalote joint venture on 1 January 2020. On 21 January 2020, B2Gold announced positive results from the updated preliminary economic assessment (PEA) for the Gramalote Ridge deposit, a part of the Gramalote project. The PEA updates and enhances previous studies on the Gramalote project in several areas, which are listed in the announcement Updated Preliminary Economic Assessment for the Gramalote Project in Colombia made in January 2020
B2Gold is currently completing approximately 42,500m of infill drilling at Gramalote Ridge to convert the existing Inferred Mineral Resource to the Indicated category, and 7,645m geotechnical drilling for site infrastructure.
The Gramalote joint venture will continue to advance community resettlement programmes, establish coexistence programmes for small artisanal miners, to work on health, safety and environmental projects and to continue to work with government and local communities on social programmes. B2Gold, as manager, plans to continue to complete and submit the feasibility work by 31 December 2020. Given that the volume of work completed by AngloGold Ashanti over the past several years – including extensive testing programmes, work with local communities and small miners and the high level of engineering performed in 2017 for an internal study – the remaining work required to complete the final feasibility study is not extensive. The main work programme for feasibility is infill drilling to confirm and upgrade the Inferred Mineral Resource to the Indicated category. The budget agreed by the joint venture partners for the feasibility study is $37m.
The Environmental Impact Study and Project Implementation Plan for the Gramalote project have been fully approved by the National Authority of Environmental Licences of Colombia. Due to necessary modifications to the processing plant and infrastructure locations, a Modified Environment Impact Study and a Modified Project Implementation plan were submitted and are currently in the final stages of approval. If the final economics of the feasibility study are positive and the joint venture makes the decision to develop Gramalote as an open pit gold mine, B2Gold would use its proven internal mine construction team to build the mine and mill facilities, and operate the mine on behalf of the joint venture.
The Quebradona deposit is located approximately 104km south-west from Medellin, Antioquia Department and is a porphyry-related, copper-gold mineralised stock work system, located within the Western Cordillera of Colombia. Until 2019, the project was a joint venture with B2Gold (5.7% and diluting) and AngloGold Ashanti (94.3% and operator). During 2019, the 5% dilution threshold was reached and the parties entered into a royalty agreement in which B2Gold transferred the minority interest in the joint venture to AngloGold Ashanti in exchange for a royalty fee during production.
During the year, AngloGold Ashanti continued with the exploration programme, with the key aim of developing the feasibility study, completing and submitting the environmental and construction licence requests (filled in November 2019), and securing the land required for project implementation. The Quebradona project is an attractive business case of ~8.7Moz gold equivalent, with required capital investment estimated at around ~$1b and an internal rate of return at approval stage of 15% (meeting our required hurdle rate).
2020 will be a critical year for the project, with an estimated investment of approximately $64m, targeted at the following key milestones:
- Complete the feasibility study and present it to the board for approval in November 2020
- Obtain the environmental and construction licence by November 2020
- Complete the process of securing the land for project implementation
The La Colosa project is located approximately 150km west of Bogota in the Tolima Department. It is a very large porphyrystyle gold deposit discovered by the Colombia greenfields exploration team in 2006. The project is 100% owned by AngloGold Ashanti. The project comprises a singular large deposit likely in excess of 28.33Moz of Mineral Resource and endowment. The project’s prefeasibility study began in 2010 and was formally put on care and maintenance in April 2017. A second-time force majeure was granted pending environmental permits. The force majeure is expected to be renewed in June 2020 if the conditions associated with the environmental licence permits remain.