Amid global market volatility and record-high gold prices, FLS’s Knelson gravity separation group has been collaborating with producers to maximise the potential of their operations. IM recently caught up with Chris Arnold, FLS Product Manager for Knelson Concentrators, for some insights into the upsides of the equipment, and recent improvements that have been made.
Arnold says increased gold prices has meant the use of gravity concentrators in polymetallic operations even those with minimal gravity-recoverable gold can significantly improve profitability by integrating compact, efficient gravity circuits. These circuits not only recover gravity-recoverable gold to a sell able product, but also prevent overgrinding, which can render gold unrecoverable in downstream processes. Typically, Knelson concentrators are installed either in primary grinding circuits to recover coarse gold or in regrind circuits to recover ultra-fine gold using a patented cone technology, which offers the industry’s best ultra-fine gold recovery.
A Knelson Concentrator at Newmont’s Cadia operation was recently coloured pink by the customer working with Consep Engineering in support of breast cancer awareness
With the shift of gold installations in large copper mines and the gold industry’s move toward high-tonnage, low-grade operations, he says the Knelson QS70 concentrator has experienced record demand. It is the largest available concentrator in the industry boasting 2.5 times the capacity of the next largest uni – it provides significant operational advantages, including a smaller installation footprint and reduced need for extensive upstream and downstream infrastructure for the same tonnage treated.
Enhancing performance with new technologies
Improving concentrator performance has been a key focus of developments at FLS. Recent design improvements enhance uptime and simplify maintenance. Intensive development of wear resistant components and superior part manufacturing techniques have resulted in longer service life and improved performance. The QS Series, a simplified deign with a low centre of gravity with and fewer components further reduces maintenance needs while maximising availiability.
Additionally, the development of new GX cone technology has improved gold recoveries while delivering environmental benefits, such as reduced water consumption and longer wear part life. The Knelson concentrator utilises a fully fluidised bed that upgrades minerals uniformly across the entire cone surface, ensuring maximum efficiency and consistent recovery. Arnold says that surveys have shown that under-fluidised cones and dry run-up zones, significantly reduce performance across multiple size fractions. Therefore, maintaining a fully fluidized cone is essential for optimised performance. FLS also provides application specific cones for coarse, fine and ultra-fine gold recovery.
FLS says it has also advanced this technology with the new GX cone, which provides greater control over fluidisation water. This advancement enables more balanced fluidisation water flows, reduces overall water consumption, and allows for customised cones designed to target specific particle sizes.
Data-driven optimisation Through KC*ModPro
As part of FLS’s efforts to assist with plant optimisation, FLS regularly works closely with plant operators to conduct detailed metallurgical surveys. The results of these surveys are then used as input for the FLS Proprietary Gravity Model (KC*ModPro), which predicts expected performance changes when plant or equipment modifications are made.
This extensive dataset of operating plant audits, combined with tried-and-tested results, enables FLS to provide dependable predictions of gravity performance for both operating and greenfield projects. This gives clients the required confidence when making costly capital or operational expenditure decisions related to the plant.
The proprietary modelling exercise also helps FLS to identify key factors that truly affect gravity recovery and how to optimise them. In most cases, gravity performance is not just driven by Knelson concentrator performance, which is very consistent from site to site, but by other factors such as cyclone performance, ensuring good circulation of GRG in the mill, or screening performance to maximise the tonnage entering the concentrators.
Success at Ghana’s Tarkwa processing plant
The retrofitting of a gravity gold recovery circuit at Ghana’s Tarkwa processing plant FLS says illustrates the effectiveness of Knelson Concentrators in optimising gold recovery in metallurgical operations.
During the project, extensive metallurgical test work highlighted the potential for Knelson Concentrators to improve gold recovery from both fresh ore and CIL tailings. The concentrators demonstrated remarkable efficiency in capturing a higher proportion of coarse gold particles, which are often lost in conventional processing circuits. The substantial recovery from CIL tailings FLS says further demonstrated Knelson’s capability to enhance overall plant performance, validating the initial investment in this technology.
Financial modelling demonstrated that implementing the Knelson Concentrator system not only increased total gold recovery by 0.6%, but also reduced reagent consumption, resulting in significant cost savings. FLS adds that with approximately 5,250 additional ounces of gold recovered annually, the financial benefits underscore the concentrator’s strong return on investment, resultsing in a 16 month payback on the project. Reduced cyanide usage and lower operational costs were highlighted as additional advantages of effectively integrating the Knelson technology.
The success of the Tarkwa plant FLS says highlights the pivotal role that Knelson Concentrators play in modern gold recovery operations. Their ability to enhance recovery rates, minimise loss, and lower processing costs it argues positions them as a superior choice for mining operations seeking to maximise efficiency and profitability in gold extraction.
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