MINERAL SEPARATION
Installation of a custom-designed Metso MHC™ 250 hydrocyclone cluster at Hecla Casa Berardi
software available. The inlet head design allows for a smoother flow of material into the hydrocyclone for increased unit capacity. Increased unit capacity combined with minimal turbulence creates a higher throughput wet classification process.
The next-generation design of the MHC™ Series hydrocyclones drive maximum uptime along with decreasing operational costs( OPEX). The MHC™ Series hydrocyclone’ s industry-leading flow rate creates an optimal flow even with given pressure drops. Wear-resistant liners are also incorporated for increased uptime and to extend the lifecycle of the parts overall. With the single component conical section, MHC™ hydrocyclone provides an ease of maintenance reducing downtime. The liner changes are quick, safe and easy due to the simple design and limited number of parts. The simplicity of the hydrocyclone brings increased uptime and reduced costs.
At Hecla Mining’ s Casa Berardi operation, a major process transformation has reshaped the performance of the site’ s grinding and classification circuit. Historically, the mine relied on a two-stage cyclone arrangement that struggled with low efficiency, high operating pressures, excessive wear, and limitations imposed by the mill building’ s overhead crane height. Together, these constraints hindered recovery performance and increased maintenance demands, signalling a clear need for modernisation.
The breakthrough came with the adoption of a custom-designed Metso MHC™ 250 hydrocyclone cluster installed at a 60-degree inclination. After evaluating several configurations, the team selected a twelve-unit system that fitted seamlessly
26 within the height restricted space while allowing proper piping slope and full crane access, crucial factors for a safe, maintainable circuit layout. Despite the compact footprint, the new cluster delivered the required classification precision, targeting an overflow P80 near 100 µ m while operating at significantly lower pressures than the legacy system.
Operational data from 2023-2024 highlights the impact of the upgrade. The circulating load surged from 185 % to 290 %, enabling more gold-bearing material to be captured by the gravity circuit. Feed tonnage to the gravity concentrator climbed from 102 t / h in 2020 to 136 t / h in 2024, directly supporting improved gold recovery. Average gravity recovery improved from 33 % to 38 %, ultimately contributing to a recovery increase averaging 1.57 %, equating millions of dollars in additional gold production.
Commissioning wasn’ t without its challenges, ranging from fines bypass to underflow launder flooding and flowmonitoring hurdles. However, each issue was systematically addressed through equipment adjustments, launder redesign, and improved instrumentation. Metso;“ Today, the Casa Berardi grinding circuit operates more efficiently, safely, and sustainably. The partnership between Metso and Hecla Mining not only delivered a more robust classification system, it also unlocked greater gold recovery and long-term operational resilience.”
On latest Metso MHC™ Hydrocyclone development, it says the new, unique and patented MHC™ Hydrocyclone curved bottom is a breakthrough for classification processes. It offers increased unit capacity and coarser cut sizes whilst minimising the fines bypass. The new design helps in significantly improving overall efficiency of the solution.
Metso:“ The MHC™ Hydrocyclone curved bottom is ideal for various applications requiring a coarse cut, where a larger diameter cyclone would traditionally be required. This can be for typical flow rates or for lower flow rates more suited to a smaller diameter cyclone. It also excels in coarse particle flotation circuits, where the production of coarser products with sharp cuts is essential. For desliming duties, it minimises the amount of fines in the underflow, thus ensuring optimal performance. It is also suitable for coarse grinding duties and can effectively address applications that are bottlenecked by the capacity of existing hydrocyclones.”
Multotec’ s GV Cyclone and managing tailings
Multotec’ s GV Cyclone it says has been designed specifically for tailings dam applications, and engineered with these priorities in mind, delivering durability, flexibility, simple maintenance, and process efficiency. Its lightweight spin-cast steel shell is lined with bonded rubber, ensuring it can withstand pressure fluctuations while remaining easy for operators to move on-site.
“ By improving material distribution, Multotec’ s GV Cyclones help mining operations reduce their environmental impact while maintaining safe and efficient tailings deposition,” says Ernst Bekker, Cyclone Product Specialist at Multotec.
A leading South African gold producer, committed to reducing the environmental impact of its tailings deposition, sought a more efficient solution for slurry management. With strict operational and environmental performance standards in place, the safety and reliability of its tailings infrastructure were non-negotiable.
Multotec had already built a longstanding relationship with the client through its work on other TSFs and gold processing plants, where it extended equipment wear life, optimised cyclone performance, and supplied fit-for-purpose solutions such as screening media, automated mechanical samplers, and mill liners. This track record made Multotec the natural partner for the new TSF order.
The mine’ s focus on leveraging modern technology to enhance operational performance while reducing environmental impact placed high demands on cyclone durability, flexibility, and efficiency.
Handling large tailings volumes under tough conditions had placed pressure on the existing deposition equipment, highlighting the need for a more reliable and operatorfriendly solution. Earlier deployments of Multotec cyclones had already proven their performance advantage over competing systems, encouraging the decision to order the GV Cyclones for the new facility.
To configure the GV Cyclones, Multotec conducted both in-house simulations and test work, supported by on-site comparative equipment trials. These trials evaluated material behaviour, confirmed achievable recoveries, and provided accurate tailings samples for further testing. To ensure
International Mining | MARCH 2026