High-rate fluidized-bed ferric sulfate generation for hydrometallurgical applications

Jaakko A. Puhakka, Päivi H.M. Kinnunen, Tuomas Van Der Meer, Bestamin Özkaya, Erkan Sahinkaya, Anna H. Kaksonen, Pauliina Nurmi

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

3 Citations (Scopus)


An overview is presented of a multi-year research effort on developing high-rate fluidized-bed bioprocesses for ferric sulfate production to be used as a unit process in various hydrometallurgical applications including indirect tank leaching of ore concentrates, regeneration of heap leach liquors and control of iron containing acidic mine wastewater. Iron oxidation rates of over 26 kg m-3 h-1 were achieved at hydraulic retention times of less than 1 h at 37°C. Oxygen supply became the rate-limiting factor even with 99.5% dioxygen aeration. Fe2+ oxidation proceeded at pH below 1 even in the presence of 60 g Fe3+ L-1 allowing the regeneration of concentrated ferric sulphate solutions required in indirect tank leaching of sulfidic ore concentrate applications. Of several tested FBR carrier materials activated carbon was the most suitable based on its availability, long-term durability and the achieved high iron oxidation rates. Jarosite precipitates accumulating to the top of the inert carrier materials played an important role in the FBR biomass retainment. For regeneration of synthetic and actual sulfidic ore heap leaching liquors, a gravity settler was installed in the recycle line of the FBR. The system produced iron precipitates with good settling characteristics and settling tank effluent with low turbidity and suspended solids concentrations. These results revealed the potential of FBR process in both heap leach liquor regeneration and controlling the iron containing waste streams. The PCR-DGGE-partial seguencing of the 16S rRNA gene protocol revealed that the FBR culture at 25-37°C remained dominated by Leptospirillum ferriphihtm over a range of operational conditions studied over the years. A modeling approach for managing Fe3+ production by FBR in combination with heap leaching was based on an artificial neural network-back propagation algorithm (ANN-HEAP) and resulted in excellent match between the measured and the predicted concentrations. High-rate fluidized-bed iron oxidation is amenable to regeneration of tank and heap leaching solutions as well as controlling iron containing waste streams.

Original languageEnglish
Title of host publicationBiohydrometallurgy
Subtitle of host publicationFrom the Single Cell to the Environment
PublisherTrans Tech Publications
Number of pages4
ISBN (Print)978-087849452-1
Publication statusPublished - 1 Jan 2007
MoE publication typeNot Eligible
Event17th International Biohydrometallurgy Symposium, IBS 2007 - Frankfurt am Main, Germany
Duration: 2 Sept 20075 Sept 2007

Publication series

SeriesAdvanced Materials Research


Conference17th International Biohydrometallurgy Symposium, IBS 2007
CityFrankfurt am Main


  • Back propagation algorithm
  • Carrier material
  • Fluidized-bed reactor
  • Iron oxidation
  • Kinetics
  • Neural network


Dive into the research topics of 'High-rate fluidized-bed ferric sulfate generation for hydrometallurgical applications'. Together they form a unique fingerprint.

Cite this