Monday, 6 June 2016

Challenges in processing nickel laterite ores by flotation

It's a shame that the highly depressed nickel market led to the cancellation of MEI's October Nickel and Cobalt Processing conference, as there are enormous challenges in the processing of nickel ores, particularly the laterites. The majority of the world's nickel resources occur as laterite ores, which are complex, low grade, and expensive to treat using conventional smelting and high-temperature and/or high-pressure autoclave methods.
However, while about 70% of the nickel resources are contained in laterites, only 40% of the world's nickel production comes from these ores. This is likely to increase as nickel laterites are becoming more attractive for production of nickel as the amount of high-grade nickel sulphide ores is diminishing. Therefore more economic processes to recover nickel from these resources should be developed, and a paper by Saeed Farrokhpay and Lev Filippov of Université de Lorraine, France, has just been published in International Journal of Mineral Processing, reviewing the challenges in processing nickel laterite ores using flotation.
Flotation has not been successful in recovering nickel from laterite ores, as the nickel is often finely disseminated in various minerals at a very fine size. Ultrafine grinding has to be used to liberate nickel-containing particles, but the resultant fine particles means that recovery is low in conventional flotation cells. The authors suggest that using reactor–separator cells, with more probability of particle–bubble attachment, could be useful to recover fine particles and these types of cells (or similar) should be tested in processing laterites. In addition, increasing particle size often results in enhancing the particle–bubble interaction in flotation, so selective flocculation of fine particles could be a key parameter in improving flotation performance. It is therefore suggested that flocculation of these type of ores needs to be thoroughly investigated.

Food for thought which may sow the seeds for future research projects?
 
Twitter @barrywills

14 comments:

  1. I think that in general the conventional flotation cells are not fit for what happens and for what is needed in flotation. What is needed is the development and implementation of more efficient flotation machines. The Staged Flotation Reactor (SFR) is a very good example of a more efficient flotation cell.
    Juan J. Anes, Canada

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  2. The limonite fraction is a big portion of the laterites. They are viscous, fine and mineralogically almost the same for gangue and pay-minerals. Collection chemistry, hydrodynamics, entrainment, tailings thickening etc. all come up as fatal flaws for limonite flotation. But then I did not used to beleive that you could heap leach the stuff either!
    Adam Johnston

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  3. Nickel price is already low (3.9 USD/lb) with just 40% coming from laterite. floating is in deed challenging, processing issues aside, but economical feasible?

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    1. Hi,
      Can you please talk about nickel ore price? Example: How are change price by MgO in nickel concentrate.

      Delete
  4. Need some great understanding of the mineralogy - what minerals, what state of dissemination, etc. Ultrafine grinding to liberate ultrafine minerals followed by poor recovery may not have great economics. Perhaps not even with higher recoveries. It will be interesting seeing the sensitivity analysis around this.
    Robert Seitz, Freeport-McMoRan, USA

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  5. As far as I know, nickel laterites are not amenable to enrichment by flotation. Some work has been done on carbonylation as an enrichment technique, but this has been unsuccessful. As a result, upgrading by hydromet or Pyro processes are expensive in terms of capital, because whole ore processing is required.
    Eric Bain Wasmund, Eriez Flotation Division, Canada

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    Replies
    1. I agree with Eric, I am not sure if the flotation technology is determining factor, normally this ores directly reports E -Furnaces. See ANTAM Indonesia
      Evren Ören, allmineral Aufbereitungstechnik GmbH & Co. KG, Germany

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  6. Major challenge has been any discrete object (particle) to separate vs. Ni-atoms highly disseminated with no association in discrete mineralization. Some of the opportunity in note from Barry relates to discrete mineralization albeit at ultrafine size. Perhaps that can reduce the load of material requiring hydro / pyro treatment at a financially acceptable cost.
    Robert Seitz, USA

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  7. In India Ni is associated with lateritic overburden.A fine powdery form. Since its a mine overburen it is difficult to store use or beneficiate it. Since 70's all combination of processes - beneficiation, pyro-hydro were evaluated "lab sacle".. The challenge is to use th whole laterite rather than Ni extraction. Pilot scale pig iron setup were tried at IMMT Bhubaneswar but the market or economics are the pain areas..
    Bio treatment at TATA R&D, BARC , IMMT were also carried out. The presence of Ni is around 0.7-1%....

    Shall we still look into as a precious metal or just .....
    Thanks
    Rama Murthy

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  8. Mineralogy is the dominating factor. Laterites are highly altered materials with Ni (and Co) present in many phases. Basically, any phase with Fe in its lattice can host Ni. See our series of papers by Quast et al.
    William (Bill) Skinner, University of South Australia

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  9. Mineralogy is a factor to determine the flotation conditions such as p80, reagents, % solids, pH
    One could find the best flotation conditions for any ore but if the flotation machine doesn´t do its job then the float conditions will not produce the expected results
    At present I´m dealing with a flotation machine design problem. We have wemco 1+1 - 14 m3 cells to treat an ore and recently we installed outotec 100 m3 cells. The difference in metallurgy is ridiculous. It is the same ore , same reagents but the metallurgical results are day and night.
    https://www.youtube.com/watch?v=kyLOUX1q6mo
    Juan J. Anes, Canada

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  10. http://www.sciencedirect.com/science/article/pii/S0892687515001089
    Juan J. Anes, Canada

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  11. Typically nickel laterites are formed from leaching of ultramafic rocks, with the nickel depositing within several mineral and non mineral structures. At one end of the spectrum is limoniteFe(OH)?, at the other end is saprolite Mg(O,H)? in between numerous amorphous silicious mixtures. The nickel content is typically lower in the limonite phase which sits atop of the leaching profile, and higher in the saprolite phase at the bottom, however nickel content is fairly uniform within the different mineral phases. I would therefore think that the best outcome would be to separate the limonite from the saprolite and amorphus phases by flotation, but this can easily be achieved by selectively mining the laterite profile with high quality grade control. It is unlikely that flotation, or high intensity mag sep etc will achieve a better result than selective mining.
    Enzo Artone, Principal Consultant at METOPS, Australia

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    Replies
    1. Precisely my point Enzo, though you have provided much greater detail. We have worked with goethitic (limonitic), saprolitic and transition types of laterites. The only pre-concentration method prior to agglomeration and heap leach is classification - coarser material, such as quartz, rejected. Flotation, magnetic, gravity all send as much Ni to con as tail.
      Bill Skinner, Australia

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