Tag Archives: Tropicana

AngloGold, IGO eye Tropicana production flexibility as Boston Shaker goes commercial

AngloGold Ashanti, in conjunction with its joint venture partner IGO Ltd, has declared commercial production at the Boston Shaker underground mine at its Tropicana gold operation in Western Australia.

Situated some 330 km east-northeast of Kalgoorlie, the operation is managed by AngloGold Ashanti Australia (AGAA) with a 70% interest, while IGO holds the remaining 30% interest.

Development of the Boston Shaker mine was approved in March 2019, and the mine transitioned into commercial production this month on schedule, below the A$105.7 million ($77 million) budget and, importantly, with no recordable safety incidents, AngloGold said.

Boston Shaker will deliver around 1.1 Mt/y of ore at an estimated grade of 3.5 g/t, contributing some 100,000 oz/y to gold production over a seven-year mine life.

“Underground mining at Boston Shaker will leverage further value from this high performing operation, achieving payback in just over three years with upside potential as the deposit remains open at depth,” AngloGold Ashanti SVP Australia, Michael Erickson, said. “The underground mine will contribute higher-grade mill feed from the current quarter onwards, improving the gold production profile and enhancing cash flow during calendar 2021-2023 when the mine plan includes periods of higher waste stripping in the Havana open pit.”

AngloGold has previously said operational excellence work at the underground mine is focused on remote bogging, the mechanical operator-controlled digging of ore from surface, and on optimising level spacing and extraction ratios.

The first production stope was fired in June 2020 and underground ore production has now reached an annualised production rate of 700,000 t/y with the design production rate expected to be achieved in March 2021.The commercial production milestone at Boston Shaker comes after Tropicana produced its 3 millionth ounce of gold in March this year, just seven years after pouring first gold in September 2013.

AngloGold explained: “From commencement of the operation at Tropicana the mining strategy has been designed to optimise cash flow, net present value and the delivery of ore. The Tropicana, Havana, Havana South and Boston Shaker open pits have been mined as a series of cutbacks, sequenced and scheduled to maximise value at a mining rate that delivers the best mining unit cost for the scale of the operation.”

Up until June 2020, ore production from the open pits exceeded the plant capacity, allowing higher-grade ore to be preferentially treated, while lower grade ore was accumulated on stockpiles. Over the course of the second half of 2019 and first half of 2020, the Tropicana pit and Havana pit were completed, in line with the mine plan. As a result, grade streaming came to an end and stockpiled ore is currently being used to supplement the mill feed from the Havana South and Boston Shaker pits.

A decision was made in the June 2020 quarter to invest in the next cutback of the Havana pit (Stage 2) which will allow access to the deeper Havana open-pit ore from 2022 onwards. While this cutback is being completed, mill feed will be sourced from the Boston Shaker open pit, supplemented by some 4 Mt/y of low grade (0.85-1.05 g/t) stockpiled ore, resulting in a lower milled grade over the period. The lower grade will be partially offset by the Boston Shaker underground mine, which is ramping up and will be contributing at full capacity by the second half of 2021.

The plan remains for gold production (at 100%) in 2020 and 2021 to be between 400,000-450,000 oz, compared with 513,785 oz last year. From 2022 onwards, annual gold production will normalise between 450,000-500,000 oz as the low-grade stockpile ore in the mill feed is displaced by a larger proportion of Boston Shaker underground ore and an increasing contribution of higher-grade ore from the Havana pit, as the cutback progresses.

AngloGold says significant potential remains to unlock known extensions of mineralisation beneath the Tropicana and Havana open pits and the extensions at depth of the Boston Shaker Underground. Development of an underground drill drive from the Boston Shaker Decline is well advanced with a total of 240 m completed to date. The drill drive is well positioned to also provide production access to the Tropicana underground reserve should the drilling prove successful. Underground diamond drilling is scheduled for the December 2020 quarter with a decision to mine expected during 2021.

Final trade-off studies are currently being completed on the Havana Stage 3 open pit cut-back and Havana underground to determine the optimal open pit – underground interface. A decision on the way forward for Havana Stage 3 is expected to be made during 2021.

(photo credit: Macmahon)

Macmahon, Flanders help automate Cat drills at Tropicana gold mine

The rollout of a A$6 million ($4.3 million) autonomous drill fleet at the Tropicana gold mine in Western Australia is believed to be an industry first for hard-rock mining, according to the mine’s contractor, Macmahon Holdings.

Macmahon says the use of hammer drilling versus the more traditional rotary concept when it comes to blasthole drilling is unique in the hard-rock space.

AngloGold Ashanti Australia (AGAA), with support from Flanders, a technology innovator and leader in autonomous drilling, and Tropicana Mining Alliance partner, Macmahon Holdings, now has five autonomous CAT MD6250 drill rigs and seven manned rigs as part of its drilling fleet.

Mining at Tropicana, which is 70% owned and managed by AngloGold Ashanti Australia and 30% by IGO, is carried out by Macmahon.

The fit out of the fifth rig in August comes only four months after the first rig was commissioned on April 27 and incorporates the ARDVARC drill control system with multi pass and down-the-hole modes to provide seamless operations with the site’s recently-installed long term evolution (LTE) telecommunications network, Macmahon said.

The project was initiated by AGAA Manager: Technology, Martin Boulton, who developed the original project scope before engaging Macmahon to further develop the business case.

He has been integral in developing the roll out schedule and managing the various technical linkages such as running the solution on the Tropicana LTE platform, according to Macmahon. This work led to the project taking out the AngloGold Ashanti Zero HARM (Hazard & Risk Management) Award in 2020.

“The autonomous drill fleet roll out has had many benefits with increased operating efficiency and asset utilisation as the equipment can operate through lightning and inclement weather, explosive detonation and eliminates the need for operator fatigue breaks,” Boulton said.

It also introduces a safer, risk-reduced method in production drilling, increases asset availability and operating efficiency and decreases asset wear, according to Macmahon.

While still early days, the autonomous fleet has already recorded an 8% increase in instantaneous penetration rates compared with the manned rigs, along with a 14% reduction in delay times in June compared with May.

These improvements can be attributed to the rigs’ ability to continue to drill safely during live blasts and lightning storm, while delays have also been removed from water refills and shift changes, the company said.

Tropicana Autonomous Drilling Systems Specialist, Richard Hill, said the autonomous project was testament to the team on site and at Flanders, and had come a long way in a relatively short period of time.

One person (drill controller) can operate up to five rigs from the one console located in the administration building at Tropicana with the automated rigs supported by two ground crew on the pit floor. To date, up to three rigs have been operated from the one console.

With roster changes on a two weeks on and one week off swing, that equates to three crews (with one back-up per crew).

“The plan is to have six drill controllers when fully mobilised, one main controller and a backup per crew,” Hill said.

However, like any new concept, it was not without some early teething problems.

The first was rod feed rates, particularly when it came to transitional ground, but the solution came with development of a new bit chasing logic and the plan is to also develop an automated bit changer that would further reduce delay times, Macmahon said.

Another challenge was managing the autonomous operating zones, which are currently required to run separately from the manned rigs as they were not equipped with collision avoidance software.

“We are working on that now and within the next couple of weeks should be able to incorporate those in the collision avoidance, and that will then increase our production as we will not have to change work areas as often,” Hill said.

Manning has also been an issue in terms of availability of ground crews to support the drill controller, but the role will now be classified as an entry-level position with a clear career pathway progression for new entrants.

Macmahon General Manager Plant & Maintenance, Mark Hatfield, said the company was thrilled with the overall performance of the fleet having achieved full conversion from design to installation and commissioning of the drill and remote operation centre in just eight weeks.

“The Flanders team have worked alongside our people providing specialist support for the duration of the trial on site, and remotely, and will work to provide continuous improvements in the coming months,” he said.

“The system provides an agnostic solution with a customisable capability, with all available drill data providing valuable insights for analysis and improved planning, and importantly, improving site safety conditions for our people.”

Pentium Hydro wins drilling and waterwell construction contract at Tropicana gold mine

Vysarn’s wholly-owned subsidiary, Pentium Hydro, has confirmed another major mining contract, this time with the AngloGold Ashanti and Independence Group joint venture Tropicana gold mine in Western Australia.

Pentium, which was only acquired from Ausdrill last month, is to provide dual rotary drilling and waterwell construction services at the mine.

Earlier this month, Pentium announced a purchase order worth up to A$800,000 ($549,866) with Fortescue Metals Group at the Cloudbreak iron ore operation.

Under the contract, Pentium will drill and construct de-watering at various locations at the Tropicana mine site including the bore fields, tailings storage facility and open pit areas.

Pentium has commenced procurement of the long lead time materials with mobilisation of the drill rig and auxiliary plant to be completed by early October, Vysarn said. The scope of work is expected to commence shortly thereafter and be complete by mid December 2019.

Pentium Managing Director, Sheldon Burt, said: “This is the fourth rig mobilised by the company in less than a month since acquiring the hydrogeological drilling assets from Ausdrill and confirms the board’s confidence in the underlying demand for the company’s assets and services. We are delighted to be working for a company of AngloGold Ashanti’s standing.”

Tropicana is owned 70% by AngloGold (manager) and 30% by Independence Group. The open-pit operation poured first gold in September 2013.

Macmahon to go underground with AngloGold, IGO at Tropicana gold mine

ASX-listed Macmahon Holdings says it has been issued a Notice of Award by AngloGold Ashanti, its client at the Tropicana gold mine in Western Australia, for the development of the new Boston Shaker underground mine.

Tropicana, a joint venture between AngloGold (70% and manager) and Independence Group (IGO, 30%), is already Macmahon’s largest mining contract in Australia.

The addition of the Boston Shaker underground work is worth approximately A$170 million ($121 million) over five years, according to Macmahon, which said it expected to commence work in May with contract documentation finalised by the parties in the coming weeks.

Capital expenditure for the underground works is estimated to be approximately A$30 million, and will be primarily spread across the first three years, Macmahon said.

The development of the Boston Shaker underground mine will enable Tropicana gold production to be maintained at between 450,000-500,000 oz/y of gold over the five years to and including the 2023 financial year, AngloGold and Independence Group said. It is expected to contribute 100,000 oz/y to the operation, with first gold expected during the September 2020 quarter. The feasibility study estimated a capital cost for the project of A$105 million.

Macmahon’s Chief Executive Officer, Michael Finnegan, said: “We are excited that our long-term alliance partnership with AngloGold Ashanti and Independence Group has grown to also include its new underground development at Tropicana, where we have been operating the surface mining since 2012.

“This contract win is a major step towards our strategic goal of growing our underground business and capitalising on the increased level of underground opportunities with existing and potential new clients.”