Tag Archives: Victoria

CSIRO’s Swirl Flow in the mix at Kirkland Lake Gold’s Fosterville mine

Kirkland Lake Gold’s Fosterville gold mine, in Victoria, Australia, has employed one of CSIRO’s innovative gold processing solutions to improve safety for workers maintaining the slurry mixing tanks at the operation.

CSIRO’s Swirl Flow offered Fosterville workers superior mixing and suspension, while minimising problems associated with dead zones and sedimentation, according to Australia’s national science agency.

Slurry mixing is an integral part of the Fosterville operation, CSIRO said. “Due to their configuration, conventional agitators tend to create dead zones in which there is little movement in the mixture, resulting in the precipitation and build-up of unwanted scale.

“Fosterville Gold Mine was managing scale build-up through frequent tank wall cleaning and ‘dropping’ (ie draining) tanks,” CSIRO said.

However, the possibility of pieces of scale breaking off and falling when the tank is drained, or when the agitator is removed for maintenance, creates a health and safety risk for employees cleaning and maintaining the tanks.

A meeting between technical teams from CSIRO and Fosterville identified Swirl Flow as a possible option to reduce the amount of maintenance required, according to CSIRO.

“Swirl Flow offered Fosterville Gold Mine superior mixing and suspension, while minimising problems associated with dead zones and sedimentation, and has since been installed at their operation,” CSIRO said.

With an innovative, yet simple, impeller design, Swirl Flow creates a vortex, or tornado-like motion, in the tank, which prevents stagnant flow, while creating higher wall velocities to help cleanse the walls to reduce scale and build up in the tank,” CSIRO said.

Fosterville Gold Mine’s Technical Process Superintendent, Susan Mills, said: “For us, the driving benefit of Swirl Flow was the health and safety aspect. The safety of our people is paramount and the benefit of reducing the hazards of falling scale during maintenance made the decision simple.”

Mills said there other benefits.

“The actual conversion process is very straightforward and not costly to retrofit from a maintenance perspective, plus the reduction in scale build-up is anticipated to reduce operational costs incurred for cleaning,” she said.

A comparison suggests that, for a greenfields installation in the gold industry, Swirl Flow has the potential to be more cost effective than traditional systems, according to CSIRO. “It is cheaper due to its simple, light engineering design, and because steel baffle structures are not required. This lightweight design also means that retrofit costs are low to replace failed conventional agitators,” the agency said.

CSIRO Lead Scientist, Jie Wu, said: “Currently, companies tend to buy a complete processing system and not look at the individual components within that system to see if there are better alternatives.

“Processes and mixing applications vary from industry to industry, so we design a Swirl Flow system for the process or requirements of a producer’s particular processing, mixing or tank requirements.

“We look at the process, we model it and then we work with the manufacturer and the client company to optimise the performance of the Swirl Flow installation.”

CSIRO is looking to expand the applications of Swirl Flow and is interested in working with both producers and mining equipment technology and services supplier companies to help resolve operational mixing problems.

“We started in the alumina industry and are now making inroads with applications and plant trials in gold processing, uranium leaching and other minerals sectors,” Dr Wu said.

“We hope that Swirl Flow will become a mainstream alternative mixing technology for a number of applications in the minerals sector.”

Swirl Flow technology was developed with CSIRO partners at Queensland Alumina. The technology enhances the agitation process by mixing liquids and suspended solids to create a tornado-like vortex in a tank. It uses a motor, gearbox and a specially-designed radial impeller with a short shaft near the top of the tank. The system improves agitator reliability, resulting in reduced maintenance and shutdowns. Due to higher and more uniform wall veolcities, the scale formation rate is also reduced, according to CSIRO.

AuStar Gold hopes Gekko’s ILR can cope with Morning Star middlings

AuStar Gold has announced the re-commencement of gold processing at its Morning Star process plant in Victoria, Australia, and, at the same time, signed an agreement with Gekko Systems to acquire a custom-made intense leach reactor for the processing of residual sulphide/gold concentrate.

The agreement with Gekko, which should enable increased overall gold recoveries from the process plant, was the last remaining processing hurdle for AuStar, given the small component of non-free milling gold present in its ore, to maximise commercial gold recoveries, it said.

The AuStar Gold process plant at the Morning Star mine site uses standard gravity methods (enhanced by recent investment in a high-speed centrifugal concentrator to recover gold from the Morning Star and Rose of Denmark ores.

“Through the gravity process, the gold room captures approximately 65% to 75% of the gold directly to bullion, with an additional 15% of fine free gold residing in the middlings as concentrate and up to 10% of fine free gold in the gold room table rejects,” AuStar said.

The material containing the fine free gold (concentrate) not captured directly into bullion at the Morning Star plant is to be treated by Gekko Systems offsite, with expected recoveries in these two fractions of approximately 95% of the contained gold, the company said. This is expected to lift total gold recovered and sold from ore supplied to the mill to better than 90%, AuStar added.

Meanwhile, a high-speed centrifugal concentrator has been purchased to replace the smaller, hired unit presently located in the process plant which produces concentrate to be provided to Gekko. This larger unit is being installed in March.

A custom-made intense leach reactor is under construction at Gekko’s Ballarat facility, designed to suit Morning Star concentrate, and will be operational in early April, the company concluded.

Just last month, AuStar confirmed it would re-start mining activity at the historic Morning Star and Rose of Denmark mines in February, with processing at the Morning Star gravity processing plant expected before the end of that month.

Morning Star is a proven past operator, with 830,000 oz of gold at 26.5 g/t Au previously produced.

Kirkland Lake Gold cements approvals at Fosterville gold mine

Kirkland Lake Gold has received regulatory and planning approval for an on-site cement plant at its rapidly-expanding Fosterville gold mine in Victoria, Australia.

Victoria’s Minister for Resources, Jaclyn Symes, confirmed the approvals on site at Fosterville last week.

The new cement infrastructure plant will enable by-product rock to be re-inserted underground, reducing tailings and extending the life of the mine, according to the government. It will also lead to production increasing at the underground mine, it added.

Estimated gold reserves at Fosterville were recently upgraded 60% to 2.7 Moz, with production in 2019 set to come in at 550,000-610,000 oz, up from 350,000 oz in 2018.

In August, Kirkland Lake Gold secured GR Engineering’s EPC services for a paste backfill plant at Fosterville which, when in production, could produce 65 m³/h of paste to fill the stopes in the gold mine.

AuStar Gold about to start operations at Morning Star and Rose of Denmark mines

ASX-listed AuStar Gold has confirmed it will re-start mining activity at the historic Morning Star and Rose of Denmark mines in Victoria, Australia, this month.

The company, in December, said it was looking to reach the mining milestone at both projects this quarter. AuStar said it had now gained a “requisite level of confidence in its minerals inventory estimation and mine planning to start production”.

AuStar Gold CEO Tom de Vries said the decision to commence production reflected the progress that had been achieved with recent exploration activity.

de Vries said: “We have repeatedly witnessed diamond drill core with visible gold and accompanying outstanding high-grade assay results, which gives us confidence that mining can be undertaken successfully.

“Our process plant is proven, the infrastructure is all well tested, and our exploration work gives us confidence that we have high-grade material available for mining. We have conducted extensive work internally to assess potential production rates and costs and the board and management are confident the decision to commence production will generate positive results for shareholders. While initial throughput rates will be modest, further exploration success will enable increased production over time,” he said.

AuStar Gold’s mine development plan will initially focus on exposing the reef at McNally’s and thereafter develop along the structure then targeting the stoping on the highest-grade drill holes.

Following an initial pre-development stage, a similar approach will be taken to the selective mining of Stone’s Reef, targeting zones where high-grade gold drill holes proliferated.

Development is expected to begin in the first week of February with logistics and procurement activity already underway. Processing at the Morning Star gravity processing plant is expected to start before the end of February.

The company said it has identified an initial gold mineral inventory to sustain production over the next six months, with the objective of continuing to replace and add to the current mineral inventory via ongoing exploration. The plant will initially operate at around 85,000 t/d throughput on a week on/week off basis, which is expected to increase in the next six months.

AuStar Gold said Morning Star is a proven past producer, with 830,000 oz at 26.5 g/t Au. It also comes with significant shaft access infrastructure in place and multiple high-grade zones identified and untested high grade intercepts.

The Rose of Denmark mine, meanwhile, has a long predictable dyke zone, vastly unexplored, with a fully refurbished circa-3 m wide adit suitable for mechanised mining and ore capable of processing through the fully recommissioned processing plant, AuStar said.

Rio’s Technical Development Centre on the search for jadarite process cure

Rio Tinto is developing a new chemical procedure to process jadarite, a mineral discovered in 2004 with concentrations of lithium and boron, as it looks to unlock the potential at its Jadar asset in Serbia.

The company’s Technical Development Centre in Bundoora, Victoria (Australia), in collaboration with the company’s team of global experts, is using ground-breaking methods to reduce jadarite to its component parts, according to a release from the International Mining and Resources Conference.

This will see lithium carbonate and boric acid produced from the mined ore.

Lithium is increasingly being used to produce batteries for electric vehicles and mobile phones, while borates are essential components for heat-resistant glass, fibreglass and smartphone screens.

Rio Tinto’s Group Executive – Growth and Innovation, Stephen McIntosh said Rio’s Bundoora site had an essential role in its global business.

“Our Bundoora Technical Development Centre was established more than 25 years ago. It has a proud history of applying innovative thinking to help us to maximise value in our business,” he said.

“The centre is actively involved in applying technical expertise to improve how we find, study, build, optimise and close our operations.”

Rio Tinto has built a pilot processing plant within a large shipping container to be relocated to the Serbia mine site should the project proceed to production. The company is currently working on a prefeasibility study on Jadar, the only project where there is a known occurrence of jadarite.

Rio has invested more than $100 million on the project to date. Significant investment is required to continue technical analysis and planning to move from prefeasibility to feasibility, then to construction and operation, the latter of which could occur in 2023-2024.

The resource base at Jadar is currently are 21 Mt of B2O3-equivalent and 2.5 Mt of Li2O-equivalent.

The IMARC conference and exhibition, taking place this week in Melbourne, Victoria, is developed in collaboration with its founding partners the Victorian State Government of Australia, Austmine, AusIMM and Mines and Money.