Friday, 14 May 2010

Did Column Flotation Cells ever realise their potential?



I see in an article in CIM Magazine (Vol. 5 Number 2, 2010) that Xstrata Technology, which markets the Jameson Cell (left), recently opened an office in Vancouver that supports projects throughout the Americas. Pilot campaigns at potash operations in Saskatchewan are among them.

Developed in the late 1980s (see MEI Online) by Prof. Graeme Jameson (right) and his students at the University of Newcastle, Australia, the Jameson cell has since been installed at operations around the world for the processing of base metals, coal and industrial minerals, including potash.

It is apparent that the Jameson cell is probably the most successful of the column-type cells.  When column flotation was first patented in the early 1980s, it lead to a spate of dedicated books, conferences and intensive research and publication in peer-reviewed journals.  Originally developed for cleaning, it was predicted that they would also take over rougher and scavenger duties and maybe make mechanical cells obsolete.

This hasn't been the case, however, and I have noticed that at recent flotation conferences columns hardly warrant a mention and the emphasis now seems to be more on extremely large, energy efficient, mechanical cells.

What are your views on this?

9 comments:

  1. I feel they did not, I worked on them at Uni, and we knew they had limited applications. I think the marketing over sold them, so they ended up in applications they were never suitable for, hence there was a fierce backlash against them. I still feel they should still be investigated as an option where upgrading of concentrate can be achieved through froth washing.

    I would be interested to hear some opinions from people on the flotation cell design side.

    Roger Strickland
    SNF Flomin, Australia

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  2. I'm curious from a mechanistic standpoint how have collumn cells failed? I have not had any experience with them, but have had with column processes in other applications - gas-liquid reactors, liquid-liquid extraction, and distillation. What aspect of the hydraulics have not lived up to expectations? Are they too tall, what determines the flooding point for air or liquid? I think of column liquid-liquid extraction columns (or even distillation columns) and note that they represent multiple equilibrium stages stacked vertically. Can that not be done with flotation? What has been tried regarding stacking of perforated distributor plates spaced vertically? At least this would limit the coagulation of air and liquid into large bubbles or masses. Would that help?

    Larry M. Southwick, Principal at L.M. Southwick & Associates, USA

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  3. We successfully installed and operated two separate column flotation cells back in the early 1990's in a nonmetallic processing operation. One unit was used in a rougher flotation application, removing iron mineral contaminants from a feldspar/quartz final product, while the other unit was used as a final cleaner flotation application for our primary product, a spodumene concentrate. Although the learning curve was lengthy, from on-site pilot plant operation to small-scale operation to final full-scale installation, we were happy with its overall performance in our facility.

    Jim Harkins, R.T. Vanderbilt, USA

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  4. John Willis, SRK Consulting UK19 May 2010 at 20:50

    Without wishing to be too simplistic, I think column cells were just rapidly overtaken by pneumatic cells (Imhoflot, Jameson etc) which shared the floorspace advantage over mechanical cells, but had a headspace advantage over columns and equal if not superior flotation performance.

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  5. Agree with the above, when applied properly they work well. I've also met some metallurgists who are fiercely opposed to them; some have had experiences with poor column cell applications that resulted in reduced performance. Column cells are also easy to blame for poor circuit performance regardless of the root cause (I've seen some operations where columns are almost tied with "bad ore" for explaining poor circuit performance)

    When operated correctly with wash water and positive bias, they are good for making concentrate grade (albeit at the expense of recovery). Modern float circuit design is an economic optimization exercise in which the final circuit configuration is that at which the project NPV would decrease by either adding equipment or removing it (in theory, anyway; often we are limited by missing or wrong information). For this reason, columns tend to find a place as the last flotation stage or stages in a typical cleaning circuit, where the objective is making a good concentrate grade without worrying too much about recovery (because you have cleaner scavengers treating the column tails). For this application, the capital and operating costs can often be reduced by using columns, rather than a series of mechanical cells that would require very slow pulling rates in order to reduce water recovery and solids entrainment to the concentrate.

    The grade-recovery curve of a column can be pushed to the right by installing hydrodynamic reactors (as in the Contact Cell, Jameson Cell, MicroCell, etc). I think this is where columns will go in the future.

    Also note that I've had bad luck with columns and other pneumatic cells in any kind of application in which agitation is important. I'm thinking of inverse flotation of silica using starches-- typically a lot of mixing is required.

    Peter Ameluxen, Aminpro Chile

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  6. On a historical note, I seem to recollect that he earlyflotation cells became only successful when they became "mechanical", i.e. agitated by impellor. In a way, the flotation columns of the 80's were a return to the non-mechanical early cells. Every adventurous mill metallurgist with a large diameter pipe and an air sock in stock had a go at column flotation. Many of these devices ended up in the scrap yard, their trial unreported. Some succeeded and were described in the various Conferences Barry has referred to.In a way it was an industry reaction to the high cost per cubic feet of the cells available then, 50 cu ft being the norm for a long time. They became obsolete with larger mined tonnages. The "unit" cell was another industry reaction, providing lower cost volume. The flotation cell manufacturers did not lead here, they followed.

    Returning to the flotation column, John C. Schneider, inventor of the PROCHEM hydrofoil agitator and its supplier to the industry, formed the opinion in the mid 80's that flotation column efficiency would only become equivalent to that of the mechanical cells by the columns becoming... mechanical! Thus the agitated flotation column concept was born.

    I was the person charged at the time with reducing this concept to practise. In 1987, PROCHEM installed a 1.6 m diameter, 6 m high, 5 stage agitated flotation column at Dickinson Gold mines in the Red Lake camp, N.Ontario.The column handled 100 t/day AsPy rougher con (produced from filtered cyanide leach residue), yielding approx. 25 t/d final concentrate (Column Flotation,'88,Chapter 31,pp.287-292).
    More on this installation can be found in CIM and CMP archives. It operated for years, but was never studied in detail by PROCHEM, nor by Dickinson. PROCHEM did not want to be industry leader and Dickinson lost its customer for auriferous AsPy concentrates. By the time Dickinson morphed into Goldcorp, the equipment needed replacing; PROCHEM was out of business and another mineral upgrading experiment ended.

    My personal view on agitated columns sees them as scavengers, by having multiple stages on top of each other, one can develop a deeper froth layer and apply more effective froth washing on scavenger concentrates. Agitated column development will need the input of an agitator manufacturer; it takes specialized knowledge to design long, multiple, stable! impellor shafts.

    Gus Van Weert
    ORETOME Limited

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  7. Recently, two type of injectors column flotation cells have been in practice. As such, the agitation and kinetics for large particle is taken care as well as the small bubbles and drainage and entraintment mechanism controlled using the wash water. I beleive the good understanding of the hydrodynamics and particle/species understanding are a fundamental step to getting the practice requered for optimization of mineral separations. You tuve version of a Froth Flotation Dynamic Simulator.
    http://www.youtube.com/watch?v=OQN5r6v9mKg
    Dr. Osvaldo A. Bascur
    OSIsoft, LCC

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  8. Recently, flotation cells/collumns with two type of bubbler/mixing have been installed a large copper sulphide concentrator in Chile. I beleive the good understanding of the hydrodynamics and particle/species flotation kinetics are a must to understand the dynamics of the froth flotation. Froth flotation is a zero order hydradynamic machine following a fluz curve behavior. Attached is a Dynamic Froth Flotation Similutor which models both the hydrodynamics and the particle kinetics of the froth flotation machines (Agited or Columns). The new column flotation machine have a bubbler for the agitation and large particles and a small sparger for small particles. By having the right entrainment and drainage rate (wash water) the optimal separation can be achieved.
    Attached is You Tube recording a a Dynamic Froth Flotation Simulator.
    http://www.youtube.com/watch?v=OQN5r6v9mKg

    Dr. Osvaldo A. Bascur
    OSIsoft, LCC

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  9. go the denver cells

    ReplyDelete

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