What we offer

Before you can get the most out of your mining operation, you need to understand exactly what goes into it. And to truly understand the ores your business is built on takes reliable, dedicated and thorough hydrometallurgical testing. Having recently integrated with the AuTec Legacy laboratory, FLSmidth now offers the full range of hydrometallurgical testing and mineral processing services. These services include the following.


Pressure Oxidation (POX)

Pressure oxidation (POX) is a well-established process for pre-treatment of refractory gold ore and base metal sulfide concentrate. We have batch and continuous pressure oxidation testing equipment available for concept testing, process design or process improvement. We offer testing services suited for pressure oxidation piloting integrated with upstream and downstream unit processes. Our technical capabilities include:


  • 2L benchtop pressure oxidation testing
  • 30L continuous pressure oxidation pilot testing with full automated control and data collection (Delta V system)
  • Flowsheet development and collaboration with engineering to provide design data
  • Site-support for process commissioning or optimisation



The dissolution of metals in cyanide or acid may be the most effective method to recover metals from an ore. Lab stirred vessels, bottle roll and leach column testing provide criteria needed to design and operate a hydrometallurgical circuit. FLSmidth is well equipped to investigate cyanidation of gold ores and concentrates directly or after peroxidation. Our hydrometallurgical leaching capabilities include:


  • Cyanidation (CIP, CIL, CIC)
  • Cyanidation (CIP, CIL, CIC)
  • Bottle rolls
  • Mixed reactor
  • Column leach
  • Gold and copper diagnostic leach
  • Cyanide destruction testing


Thiosulfate leaching

AuTec and its predecessor groups have been studying thiosulfate leaching for many years, and now FLSmidth is able to continue testing this technology. In the thiosulfate leach process, thiosulfate is used as an alternative to cyanide, to enable gold recovery from preg-robbing ores. The gold-thiosulfate complex does not adsorb onto carbon as does gold-cyanide, but is instead loaded onto resin, in a resin-in-leach process.


Elution is a multiple-stage process that produces a gold-bearing pregnant solution for electrowinning. Loaded resin received from the RIL undergoes washing, copper elution, gold elution and resin regeneration. After the gold has been removed from the resin, the barren resin can be reused in the leach.



Precipitation is a process widely employed in hydrometallurgy for recovery of metal values or for removal of impurity elements from process solution. FLSmidth has the capabilities to evaluate precipitation technologies across a variety of flowsheets for impurity removal, neutralisation or metal recovery.

Stories from FLSmidth