Key Benefits

  • Integrated complete systems
  • Single source warranty
  • Proven reliable proprietary equipment
  • Reduced capital cost (Zadra)
  • Reduced strip time (AARL)

Elution/Strip Systems with optimum results every time

At FLSmidth, we understand your need to have the best systems in place to remove and recover the maximum amount of gold and silver from carbon. We provide our unmatched Elution/Strip Systems to process loaded carbon in the shortest time possible with the highest energy efficiency and with significant cost-saving benefits.

Your needs in mind

We offer systems that utilise either the Zadra desorption process, pioneered by J.B. Zadra in the 1950s, or the AARL process, from Anglo American Research Laboratories in the 1970s. Each method has its advantages over the other option, to be evaluated with your plant’s operations and requirements in mind.

Standard, modular and custom sizing

FLSmidth offers our integrated systems capable of stripping carbon from 1–72 tonnes carbon per day. Our standard designs are the most economical from a capital cost perspective and also offer the quickest delivery times. We are excited to offer completely modular plants, which minimise onsite installation time. Customisation is possible for any of our plants, though cost and delivery time may increase.


Extraction efficiency

You’ve worked hard to mine, process, leach and absorb the maximum amount of gold and silver from your ore body. Now it’s time to recover the most precious metal from your carbon as well. Our FLSmidth elution/strip circuits routinely remove precious metals below 50–100 ppm on the eluted carbon. Our circuits are healthy, maximising precious metal adsorption and minimising inventory losses in the heap or actual losses to tailings.


Don’t get caught operating with an underperforming elution circuit. Poorly performing elution circuits leave excess metal loaded on the carbon, robbing it of the activity needed to completely remove precious metals from the last contact stage in the absorption circuit.


Energy efficiency

The solution temperature and flowrate are the main controlled factors in the elution circuit.  Both are critical factors for eluting carbon with the utmost efficiency. From selecting a properly sized boiler to designing the correct amount of heat recovery in the heat exchanger skid, our designers have optimised our elution systems to yield the best possible results. 



Our circuits come complete with Elution/Strip Vessel, Solution Heater Skid, Boiler, Solution Tanks, Pumps, and Electrowinning Cells, plus all tanks, piping, instrumentation, and valves to complete the system. We match each component to work cohesively together, and we right-size vessels, tanks, pumps and proprietary equipment. Take your system to the next level. 



During the last decade, we have implemented the FLSmidth Summit Valley Split-Zadra stripping process, saving further on plant capital, installed power and operating costs.  During the standard elution process, the majority of the gold is recovered in the first half of the strip cycle and the remaining time is used to polish the carbon to low absorbed gold values. In our patented FLS-SVT Split-Zadra, as is true for the Split-AARL process, the solution from the polishing time is used as the lean eluate for the next elution cycle.  The FLS-SVT Split-Zadra is capable of saving 33% more energy on consecutive strips versus a standard elution cycle.

Elution/Strip Systems to maximise gold and silver recovery

Integrated complete systems

When you purchase an FLSmidth Elution/Strip System, you have confidence you will receive the same quality and comprehensive system our valued clients have received for over 25 years in over 75 installations. 


Our system designers work with the complete system in mind and maximise your return on investment. Each component selected has been carefully designed and built from our proprietary equipment lines or has been secured from our proven and trusted suppliers. 


All components work cohesively, maximising extraction, recovery and efficiency, and have a proven track record.

Single source warranty
You have peace in mind purchasing an FLSmidth system because we stand behind our product with a single source warranty. Each of our systems and every component in them from the inlet to outlet tie-in points are protected. If a part, component or the system is not functioning correctly, simply contact us and we will resolve the issue. Parts or items that have failed will be replaced by FLSmidth for the warranty period and under the warranty conditions. No more trying to contact multiple suppliers. We’ll take care of you.
Proven reliable proprietary equipment
Choose a complete system or select itemised equipment. All equipment from the Elution Vessel to the solution pumps has been selected to work with efficiency and longevity, providing years of trouble-free use. Our proprietary Solution Heater Skids and Electrowinning Cells have been proven in the most difficult installations around the world.
Reduced capital cost (Zadra)

The Zadra circuit has reduced capital costs, with a smaller number of required tanks and reduced footprint. Another benefit to the standard Zadra circuit is that it requires less energy than a typical AARL. It also uses less reagents than a typical AARL and does not require the high-quality water of a typical AARL.

Reduced strip time (AARL)
The main advantage of the AARL process is the ability to strip a batch of carbon to low gold residuals in an average strip time of 6–8 hours compared with 6–10 hours for standard Zadra. New plants can be designed with multiple daily stripping cycles in mind, or existing plants can have increased daily capacity by adding shifts for stripping.

Zadra vs AARL operation conditions





150° C

120° C


>285 kPa


Flow rate

2-2.5 BV/hr

2-2.5 BV/hr

Total Volume

12 – 16 BV

12 – 12 BV

Cyanide Concentration

0.1 wt%

1 wt%

Caustic Conc.

1 wt%

2 – 3 wt%


The recovery is comparable between the two, so ultimately the choice is based on specific needs. Take advantage of our globally respected experts who will discuss your individual situation and advise you which Elution/Strip System is best for your plant.

The most effective Elution/Strip System for your requirements

Whether using the Zadra or AARL processes, we offer you the most efficient Elution/Strip Systems for maximum gold or silver recovery.

Cost benefit, long life and reliability

Our standard carbon steel Strip Vessel is engineered and fabricated to ASME Section VIII and comes complete with 316SS internal screens and assemblies, as well as a rupture disk and pressure relief valve assembly to prevent over-pressurising of the vessel. Using carbon steel as the standard material reduces the associated capital cost, while still providing excellent service life and reliability.

Semi-automated and fully-automated systems

FLSmidth plants are available with minimal automation all the way to fully automated using PLC system control implemented by FLS Automation. For our fully-automated plants, we have options for programming control and architecture.

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