Shining a light on Sunrise Dam

With gold prices reaching an all-time high of $3935oz (US$2685oz) in September 2024, gold mining companies are reaping the benefits as demand for this precious metal remains elevated.

One such company is AngloGold Ashanti, owner of the Sunrise Dam operation which lies 205km north-northeast of Kalgoorlie and 55km south of Laverton in WA.

Open pit production began in 1997 and was completed at the main pit in 2014 to a final depth of 500m below surface.

After the Golden Delicious open pit was depleted last year, the main source of ore comes from the Vogue and Frankie zones, both of which are underground operations.

Underground operations and production from Golden Delicious, while it was still producing, saw 252,000oz of gold produced in 2023, up 9% from the 232,000oz produced in 2022.

AngloGold Ashanti credits this to higher recovered grades which were partially offset by lower processed ore volumes.

In 2023, 92km of exploration drilling was completed at Sunrise Dam, with a particular focus on the Frankie, Vogue and Astro-Flamingo zones.

The aim of this was to boost the mineral reserve which currently stands at 1.04moz.

Mineralisation at Sunrise Dam is typically hosted within quartz-carbonate veins, with varying quantities of pyrite and arsenopyrite.

Sunrise Dam is one of AngloGold Ashanti’s tier two assets, meaning it’s a steady performer, reliable cash generator and has a shorter mine life with an approved life planned until 2028.

Underground mining

While Sunrise Dam is 100% owned by AngloGold Ashanti, underground mining is carried out by Barminco, Perenti’s (ASX: PRN) underground mining business, with the two companies partnering together in 2003 when the first portal was cut.

In 2011, Barminco was awarded a $500m underground mining contract, the largest ever contract the company had received at that time.

The contract has been extended twice since then, with the first in 2018 for a further five years for $700m, and the second extension began in October 2024 with Barminco’s work being extended a further three years for $450m.

Mineral processing

The Sunrise Dam gold processing facility began operations in 1997 as a two-stage crushing single-stage grinding plant with a capacity of 1mtpa.

A second ball mill was added two years later to increase capacity to 1.5mtpa and another major upgrade was completed in 2001, with a three-stage crushing circuit, two-stage grinding and a second parallel carbon-in-leach circuit (CIL) being added.

This upgrade increased throughput capacity to 2.5mtpa and enabled treatment of harder material mined from deeper levels of the underground mine.

The gravity circuit recovers around 30% of the gold, with the CIL circuit is used to recover the remainder.

Currently, plant throughput at Sunrise Dam is around 4.1mtpa.

Full asset potential program

Launched in 2022, AngloGold Ashanti’s Full Potential Program aims to achieve a step-change in the operating performance and cost competitiveness across all operations.

It involves a comprehensive three-month assessment of all operating mine sites with an aim to build on the company’s understanding of the potential of each asset.

The initial three-month assessment covers mine design and all key operating parameters to identify any gaps between the current and potential performance.

Sunrise Dam was the first operation to have the Full Potential Program completed at, with increasing productivity in development and achieving a step-change in underground production the biggest opportunity identified.

Since July 2022, Sunrise Dam has achieved production rates of over 1100m per month with the target increased to 1200m per month in 2023.

As a result, Sunrise Dam has seen higher ore production of around 200,000t per month since then.

Other key initiative include: increasing plant metallurgical recovery rates through optimised cyanide and reagent usage; increasing development rates across underground operations to promote greater ore volumes; and increasing output through better maintenance practices.

The initiative ran for three months and was completed at the end of 2023.

Sustainability

In October 2022, AngloGold Ashanti set a target to reduce absolute Scope 1 and 2 greenhouse gas (GHG) emissions by 30% by 2030 compared to 2021’s baseline of 1.4mt of carbon dioxide equivalent.

“We have a clear pathway to achieve our target by 2030, when we expect to have lowered our overall emissions by almost a third,” AngloGold chief executive Alberto Calderon said at the time.

“This ensures we continue to do our part in reducing our carbon footprint, while also improving the value of our business.”

In a bid to reduce its emissions, AngloGold Ashanti has begun trials for battery electric trucks at Sunrise Dam.

World’s largest battery-electric truck begins trial

In September 2023, AngloGold Ashanti, Barminco and Sandvik began trialling the world’s largest battery-electric underground mining truck at Sunrise Dam – the Sandvik TH665B.

The truck features an advanced lithium-iron phosphate battery, meaning no underground exhaust emissions are emitted compared to traditional diesel engines.

Not only does the truck produce zero diesel emissions underground and generate 80% less heat than other underground mining trucks, it’s also 25% faster on a 1:7 ramp than regular diesel trucks.

“Trials such as this are incredibly important as they help us to understand how equipment performs in an operational environment,” Perenti head of mining electrification and technology Darren Kwok said.

“Being able to father data on the performance and capabilities of new machines allows us to piece together an aggregated view of future mines.”

The Zero Harm (Hazard and Risk Management) Award

Over the years, AngloGold Ashanti’s Zero Harm Award has provided many useful solutions to improve the safety and wellbeing of both its staff and operations.

These awards recognise the proactive and innovative measures taken to eliminate and control safety hazards in a bid to support AngloGold’s vision to have a workplace free from occupational injuries and illness.

“The awards are very well received by our employees and over the years they have delivered some very useful innovations,” AngloGold Ashanti vice president of group safety Neels Muller said.

Flashing Beacon Enhancement

One notable submission to come from Sunrise Dam was the Flashing Beacon Enhancement which provides an additional visual aid for heavy vehicle equipment in the form of a continuous and distinct beam.

Airsled

Another innovative solution is the Airsled which uses compressed air to effortlessly lift heavy appliances and equipment, reducing the need for manual handling and lowering exposure to risk and potential health and safety performance indicators.

Driftshot 4G Detonator

The Driftshot 4G Detonator has been introduced at Sunrise Dam’s underground operations to initiate development headings.

The unique safety protocols of the detonator protect against overvoltage and illegal currents, requiring a specific voltage and a coded signal via a blast control unit to initiate.

A conventional detonator is vulnerable to illegal currents and initiation, meaning headings could not be ‘wired in’ to the firing line until 30 minutes before blast times (when everyone is evacuating).

Operators then had to rush to complete the wiring which often resulted in breaches of the tagboard procedure, a process which involves underground workers placing their personal tag on a board before descending and collecting them upon ascent.

The Driftshot 4G Detonator eliminates the time pressures for those both evacuating and re entering after a blast.

Gold Room Pallet Scale

Prior to smelting, gold precipitate is stored in steel trays and these trays are typically handled manually.

A pallet scale has been installed, allowing these trays to instead be loaded via an overhead crane onto a scissor lift trolley and wheeled up a ramp onto the scale for weighing.

When the precipitate is wet, the trays can weigh up to 25kg and pose a risk to the technicians manually handling them.

This pallet scale eliminates the need for manual handling of the trays and improves staff ergonomics.