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Cyanide leach

Superior leach and adsorption circuits for optimum metals extraction

Our range of cyanide leach and adsorption circuits deliver optimised precious metals extraction from ore. Simple, affordable, and easy to maintain, we offer three circuit types that improve on traditional, highly regarded techniques to offer performance that matches your applications needs.

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Key benefits of our cyanide leach and adsorption circuits

  • Proper circuit design

    FLS leach and adsorption circuits are designed and supplied to exceed your plant specifications. We provide long-lasting circuits with careful attention to proper residence time, agitation, slurry mixing, oxygen dispersion, eliminating short circuiting, slurry density and reagent introduction, including cyanide and pH control.

  • Robust and easy to maintain

    Designed with maintainability in mind, FLS cyanide leach and adsorption circuits are engineered and constructed to high quality specifications, reducing maintenance, but allowing easy equipment access when needed.

  • Cost-effective precious metals extraction

    FLS leach and adsorption circuits extract gold and silver from ore as cost-effectively as possible. By designing and selecting the most application-appropriate equipment, we deliver high reliability and performance, exceeding expectations for total cost of ownership.

Our leach and adsorption circuits

Carbon in column 

The CIC circuit is an adsorption-only system used to treat relatively clear pregnant solutions, such as heap leach, CCD, and pre-leach thickener overflow. Upflowing tanks from an active fluidised carbon bed, which adsorbs the metal through a series of adsorption stages.

  • Smaller footprint with vertical arrangement possible. 
  • Lower installation costs. 
  • Low carbon attrition.  

Leach-Carbon in pulp  

Comprising separate leaching and adsorption tanks, the leach-CIP circuit first leaches the ore pulp in agitated tanks, dissolving the gold and silver into a slurry over 24 – 72 hours. The leached slurry is then routed to agitated CIP tanks for adsorption.  

  • Less gold lock-up. 
  • Lower carbon inventory. 
  • Interstage screens retain carbon in the tanks. 

Carbon in leach 

Combining leach and adsorption into a single process, CIL circuits introduce cyanide, ore pulp, oxygen, and carbon at the same time. Sizing of the tanks is calculated based on the time needed to complete ore leaching, usually 24-72 hours.  

  • High recovery of preg-robbing ore.
  • Smaller environmental footprint. 
  • Interstage screens retain carbon in the tanks.  

Maintenance & service of our leach and adsorption circuits

Our aftermarket department offers reliable and timely supply of spares and wear parts, ensuring minimal downtime and optimal equipment performance. Our specialists are also readily available to provide ongoing operational support. Whether it’s technical advice, troubleshooting or circuit optimization, we work closely with mine site teams to ensure the longevity and efficiency of the equipment throughout its lifecycle. Additionally, we offer comprehensive support services, including circuit audits, preventive maintenance programs, training for mine operators and maintenance personnel, and detailed reporting on equipment performance. Our goal is to help maximise recovery, minimise downtime, and ensure the safe and efficient operation of your FLS systems and equipment.

Learn more about FLS service centres

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Frequently asked questions

FAQs for our leach and adsorption circuits

Cyanide leaching, or cyanidation, is a method used to extract precious metals from ore. Ores are first crushed and ground to liberate the metal, which is then dissolved using a dilute cyanide solution. The resulting metal-cyanide complex is adsorbed onto activated carbon for downstream recovery.  

FLS offers three different tank-based cyanide leaching and adsorption processes: carbon in column, leach-carbon in pulp, and carbon in leach. Heap leaching is an alternative process in which crushed ore is piled onto an impermeable liner with the cyanide solution sprayed or dripped over the heap. The pregnant solution collects at the bottom of the rock pile.

Cyanide leaching is a simple, cost-effective, and easily scalable method of delivering high precious metals recovery, especially from oxidised ores.