Metso Insights Case studies Mining and metals refining Enhancing gold recovery and process control with the Courier® 6G SL analyzer
Jan 24, 2024

Enhancing gold recovery and process control with the Courier® 6G SL analyzer

The demand for accurate and well-maintained elemental analyzers continues to rise as ore grades decline in the mining industry. In particular, the extraction of precious metals such as gold presents a significant challenge due to their low concentration in tailings. To address this issue, the Ada Tepe mine, owned by Dundee Precious Metals, located in southeastern Bulgaria, sought to improve its gold recovery and process control, all whilst reducing any losses to tailings.
The game- changing Courier 6G SL analyzer
The game- changing Courier 6G SL analyzer

As the first greenfield mine in the country in four decades – and boasting one of the highest open pit gold grades in the world – Ada Tepe required a cutting-edge solution capable of real-time and reliable elemental analysis measurements.

Specifically designed for on-stream analysis, the Courier® 6G SL analyzer revolutionizes the direct measurement of gold, platinum, and other valuable metal concentrations in ore feed, concentrate, and tailings streams. By delivering fast and accurate elemental analysis data, the analyzer enables mining operations to have more efficient process control, thus enhancing process stability and maximizing recovery rates. The typical measurement time for gold in feed is one to five minutes, for concentrate streams 30 to 60 seconds and in tailings five to 20 minutes due to lower elemental concentrations. Total cycle time for feed, concentrate and tailings streams can be as low as 30 minutes, which enables operators to react much faster to changes in the process.

The Courier 6G analyzer's advanced technology, which features a high-power X-ray tube and measurement channels optimized for direct measurement of gold and platinum group metals, allows for the detection of low quantities of elements that were previously undetectable.

"This is our first analyzer that can measure gold directly in flotation tailings,” says Juha Timperi, Director, Analyzer Solutions at Metso. “With previous analyzers, you could measure gold in concentrate, for example. But in tailings, the gold level can be below parts per million (PPM), which has been too low for traditional on-line analyzers. With the new Courier 6G SL analyzer, our customers have been able to measure gold concentrations on sub-ppm levels as low as 0.2 grams per ton. This enables new ways to control flotation process in real-time and prevent losing gold to tailings.”


Courier 6G SL analyzer for gold
An efficient process control relies on accurate real-time measurements. The Courier® 6G SL analyzer enables direct measurement of gold from ore feed, concentrate and tailings streams.

The success story of Agnico Eagle Kittilä further solidifies the impact of the Courier 6G SL analyzer. Since October 2019, this on-stream analyzer has given the site invaluable measurement information, enhancing flotation control and optimization. The resulting improvements in the pre-flotation circuit have led to significantly reduced gold losses.

The Kittilä flotation circuit is relatively straightforward: it begins with a carbon pre-flotation followed by bulk sulfide flotation. The Courier 6G is utilized to measure gold content in the flotation feed, carbon flotation concentrates and carbon flotation tailings.

“This set-up allows us to closely monitor real-time gold loss in the carbon flotation circuit,” says Lauri Veki, Senior Metallurgist at Agnico Eagle Finland Oy, Kittilä Mine. “In carbon flotation, our objective is to minimize gold loss and maximize organic carbon recovery.”

“We employ PID controllers to regulate the airflow rates to the carbon flotation cells. This controller utilizes the current gold loss information from the Courier. If the gold loss exceeds a certain threshold, the airflow rate in the cells automatically decreases. This approach has demonstrated greater accuracy in maintaining the targeted gold loss compared to the other gold-loss control methods. Before implementing Courier 6G, we used Courier 5 to measure arsenic, which correlates with gold in the Kittilä ore. It wasn’t bad either, but we got a slightly better ratio of carbon recovery / gold loss using Courier 6G than indirect arsenic measurement. Due to ore variations, the correlation between gold and arsenic varies in the mill feed, which is the root cause of why direct measurement of gold is a better choice to control gold loss in our case.”

“Another minor advantage is that we find out the mill feed gold grade earlier than from the lab measurements,” says Veki. “This allows us to check whether the planned feed recipe is in line with the realized gold content.”

Inspired by this success, Armenak Grigoryan, Corporate Director Metallurgy & Processing, Dundee Precious Metals - was confident the Courier 6G SL was the right fit for their site.

“The main target for us was to have the right measurements of gold so that we could react to the process changes and disturbances on time,” says Grigoryan. “Thanks to Courier 6G, we have successfully achieved that.”

Courier 6G assembly
Courier 6G assembly

Increasing process control, efficiency, and profitability

Efficient gold recovery and minimizing gold losses in tailings are top priorities for gold producers. Traditionally, many mines have relied on indirect methods to estimate gold content, such as measuring copper levels in chalcopyrite ore, or in Kittilä’s case, using Arsenic as a proxy and estimating the amount of gold from there. While this approach may work in some instances, it has proved ineffective for mines like Ada Tepe, where there was no correlation between gold and other measured elements. For that reason, it was specifically required that a direct measurement of gold was needed to optimize flotation.

It was important to Ada Tepe to see how much gold they were losing to tailings in near real-time and take corrective actions to prevent any losses. Thus, it was a positive surprise for them to learn that the Courier 6G was capable of measuring gold directly in tailings in very low quantities, such as between 0.2 to 0.8 grams per ton.

Another significant challenge the site was facing was the considerable time investment required for manual sampling. Before the implementation of the Courier 6G SL analyzer, the site was relying on someone from the lab to collect 6-7 samples every 2 hours.

“Gold measurement is quite important as there are no other elements we can correlate to gold,” says Grigoryan. “In the lab, it takes at least four hours (for sample preparation and assaying) - to obtain results from the sample taken from the plant. And even then the information might be outdated as the ore feed and conditions might have changed in the meantime, thus requiring adjustments based on assumption.”

With the implementation of the Courier 6G, not only does it provide near real-time automatic measurement of gold content, but it also collects a shift sample for metallurgical accounting purposes. Samples are automatically collected by a multiplexer, filtered and is readily available for sample preparation and analysis. Consequently, the performance of the gold mine is directly reported to the management and plant operators, further enabling informed decision-making. The Courier 6G futher enable automated control and process optimization through the use of advanced control tools or plant simulators/digital twins.

“Without an analyzer, one needs fairly frequent sample collection - hourly or every two hours,” says Grigoryan. “But with an analyzer, this sampling interval can be extended to four, six, or even eight hours. Having near real-time gold measurement and the ability to react to process changes provides the opportunity to make timely and more precise adjustment, allowing for improved stability and process performance.”


Having precise and timely gold measurement and the ability to react to the changes in the process in real-time gave us the opportunity to do more accurate input at the right time.
Armenak Grigoryan, Corporate Manager, Processing at Dundee Precious Metals

These challenges are common industry issues and can affect both productivity and profitability. Though the primary intent was for better process control, inevitably this leads to cost savings as well.

“Typically, recovery increases from 1% to 3% have been recorded as a result of using Couriers to enable better process control,” says Salla Marttonen-Arola, heading Performance Centers at Metso “For example, the impact of keeping the Courier accurate and available could mean a 0.5% increase in recovery, which could mean 4.5MEUR as the value of gold.”

By overcoming the limitations of indirect estimation methods and streamlining the gold measurement process, the Courier 6G SL analyzer has enabled more efficient flotation process control at Ada Tepe mine. The ability to monitor gold losses in near real-time, along with the automation of sampling procedures, has ushered in a new era of process control, leading to increased operational performance, and ultimately maximizing gold recovery rates.

Proactive service and safety

At Metso, safety is our top priority and at the core of everything we do. Not only is it an indicator of exceptional quality, but we firmly believe that good health and safety performance is one of the keys to ensuring sustainable business.

Amongst other benefits they have been seeing, the Courier 6G analyzer is making significant strides in ensuring additional safety at the Ada Tepe mine. Unlike some competitors who rely on radioactive isotopes, the Courier 6G utilizes an X-ray tube in the analyzer, ensuring that no ionizing radiation harmful to living tissue is emitted when the X-ray tube is powered down. The absence of radiation when the energy source is deactivated makes it safe to store and transport the X-ray tubes, even via air freight.

“This is the most powerful X-ray analyzer that we've ever had, and it's designed in a bulletproof manner regarding safety,” says Timperi. “When the X-ray cabinet that stores the components with radiation is opened, the system automatically turns off as a safety feature.”

Metso also consistently reminds customers that although the analyzer incorporates automatic safety functions to prevent accidents, it is crucial that only trained personnel conduct maintenance on the equipment.

“The greatest concern lies with the human factor, where someone who lacks proper knowledge starts to conduct maintenance actions that may actually lead to the risk of accident,” says Timperi. “We are concerned for our customer's safety as well as our own service technicians, so suggest that the person operating the analyzers refresh their safety awareness every year.”

To address this, Metso places a strong emphasis on safety and requires analyzer operators to undergo annual safety refresher training. By offering free access to these training sessions through our Training Academy, we can ensure that customers are equipped to prioritize their safety.


Combining analyzers and digital solutions for real results

The scope of Metso’s solution at the Ada Tepe mine site included an Analyzer Health Management Life Cycle Services (LCS) program for the customer’s analyzers. This LCS package includes spare and wear parts, annual maintenance planning workshops, maintenance visits, and remote services from the Performance Centers and from the technical support teams.

The Performance Centers provide Metrics Monitoring Level 2 service for the Courier 6G, and their monthly service clock includes assessment reports delivered to the customer and internal stakeholders, review meetings to discuss the findings with the customer, regular calibration data analyses, as well as calibration formula updates when needed.

“The customer’s Courier 6G was connected to Metso Metrics™ in June 2022,” says Marttonen-Arola. “The first months after starting the data collection included data quality checks, ramping up the Performance Centers’ service and support model, getting to know the customer’s process and targets, and providing the customer access to Metrics.”

Along with the invaluable support of the dedicated service team, the utilization of Metso Metrics has proven instrumental in facilitating seamless communication and support between Metso experts and the operators on-site.

”We are reading the Courier 6G data in our SCADA system as well as archiving in our historian and making it available in the control room for operators, so the functionality is very useful,” says Grigoryan. “They can track grades, status of each line, if it is under maintenance, which stream are running and more - all this has been visible within the system. This is an extra plus for the Courier 6G, that remote visibility, local visibility, and flexibility on connectivity. That is a big value.”

“Ultimately, the site was looking to make the most of their Courier 6G in terms of accuracy and availability,” says Marttonen-Arola. “If the Courier calibration model is not adjusted sufficiently, the assay results and metal recovery calculations become inaccurate over time. Courier data needs to stay accurate to enable expert process control solutions, so inaccuracy leads to loss of recovery in flotation and increase in cost per ton. In terms of availability, if the Courier is not available to do what it is intended to do, process control does not have the information it needs.”

The first composite sample results were initially received from the customer back in 2021. This has allowed the Performance Centers to keep track of the equipment and continuously support keeping the Courier accurate ever since. In the figure below it can be seen that the average accuracy of the Courier measurements for flotation feed in January was 79.5%.

Metso courier measurement results
Courier measurement results vs. laboratory results in January 2023

By March 2023, the Performance Centers had performed another remote calibration for the flotation feed, and the service had matured enough for the average measurement accuracy of the Courier to reach 96.9% as shown in the figure below. This level of accuracy allows the use of the Courier measurement data in process control to optimize metallurgical performance.

 Courier measurement results vs. laboratory results in March 2023
Courier measurement results vs. laboratory results in March 2023
We are happy with Metso Metrics.
Armenak Grigoryan, Corporate Manager, Processing at Dundee Precious Metals

“We are happy with Metso Metrics,” says Grigoryan. “If there is tracking, then there can be analysis, and if there is analysis, then there will be an action plan to resolve bottlenecks or problems.”

The monthly report that Metso Performance Centers provide includes a comprehensive overview of equipment performance that enables proactive measures to address any abnormalities. By leveraging the power of digital solutions, both Metso and Ada Tepe continue to demonstrate their commitment to enhancing operational efficiency and maximizing the mine's productivity.

Revolutionizing gold recovery

The capabilities of the Courier 6G SL analyzer - such as its technical features, increased safety aspect, integration with Metrics and the Performance Centers, and transformative benefits - bring new recovery methods to gold mining operations worldwide. With this revolutionary technology, operations can now unlock unparalleled efficiency and maximize their gold recovery while minimizing losses.

By prioritizing efficiency and safety at every step, the Courier 6G analyzer sets a new benchmark for gold recovery in the mining industry. Metso understands the customer’s world and the daily challenges they face. That’s why, together, we are the partner for positive change. 


Enjoyed this article? Try this next
Courier® 6G SL analyzer product launch
In this webinar our Metso Outotec expert, Juha Timperi, introduces the Courier® 6G SL on-stream analyzer.
Read more
Contact our experts!
Your information is safe. Check our privacy notice for more details.
Thank you!
We will shortly contact you. You can send a new inquiry again after 15 minutes.