Gravity Separation & Concentration Methods

Gravity Separation & Concentration Methods 2017-04-04T06:57:23+00:00
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Compare Falcon & Knelson Concentrators (11 replies and 4 comments)

Gabriel
1 year ago
Gabriel 1 year ago

I will buy a centrifugal gravity concentration. What is better? Falcon or Knelson?

Modine96069
1 year ago
Modine96069 1 year ago
3 likes by Tererai, Bob Mathias and David

Falcon concentrators operate at higher G-Forces and are therefore better suited for fine free gold particle collection.  They are heavier, more robust machines.  If you intend to install the concentrator(s) on cyclone underflow, it makes little difference on which concentrator to install.  Operators are leaning more towards installing concentrators on cyclone OVERFLOW where there is greater mineral liberation, in which case the Falcon is a better choice of machine

Chalky
1 year ago

Has anyone on this forum has any experience with Chinese manufactured concentrators ? I am fairly certain people will tend to dismiss them, but I would be keen to hear from anyone who has actually used one. Cheers

David
12 months ago

Chalky, I would really like to hear about your experience. If you have some please post.

Gabriel
1 year ago
Gabriel 1 year ago

I will install on underflow cyclone. 

David
1 year ago
David 1 year ago

Hi Gabriel,

Welcome to 911Met

Be sure to read https://www.911metallurgist.com/blog/falcon-knelson-concentrators-compared

and watch https://www.youtube.com/watch?v=-dlSLJXf7gg&feature=youtu.be

 

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Bob Mathias
1 year ago
Bob Mathias 1 year ago
Modine96069
1 year ago

Is it not strange to ask a salesman his opinion on which is better, his product or the competitors? The salesman was wrong, André Laplante is the grandfather of gravity concentration (before Byron Knelson)

David
1 year ago
David 1 year ago

Hi Modine96069 and thank you very much for your great input.

Yea, what's the rep going to say... hmmm...  

In any case, am with you on highest G-Forces = highest fines recovery.

The voodoo around the holes and fluidized bed is not relevant. I like to compare this to religion; 3 faiths, 1 God. The God here is G-Force and you do not need to believe in the laws of gravity for them to work/apply.

Depending on the specific mineralogy and overall circuit, which machine you pick may not matter.

Gabriel, what is your downstream circuit? Flotation or Leach?

Do you know how much GRG gravity recoverable gold you have?

A Laplante paper is in the list https://www.911metallurgist.com/blog/falcon-knelson-concentrators-compared

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Gabriel
1 year ago
Gabriel 1 year ago

My circuit is leaching. The P80 of mill circuit is 80% < 74 microns. The concentrator will be install on underflow cyclone. The GRG testwork is 60%.
Actually we have three small concentrators (2 knelson and 1 falcon with 20 years old) and the gravity recovery is about the 38%. The availability the current concentrators is down. I want change the 3 old concentrate to 1 more modern. The feed rate of the mill is 130 TPH and the circuit load is 350%.
We have 1 acacia for intense leaching the final concentrate.

Colette
1 year ago
Colette 1 year ago
1 like by David

Hi Gabriel

The previous responses give a good overview of the perceived value of the two manufacturers - the Falcon has been marketed as aimed at the finer cyclone feed installation (where an offtake is taken from the cyclone distributor), and the Knelson was used in the cyclone underflow almost by default. Using cyclone underflow has been perceived as more expensive because your gravity tower has to have an additional level to it (personally I prefer it, plant surveys have clearly shown that there is a gold concentration upgrade across your cyclone to the underflow, and I like to take advantage of that).

In practice with side-by-side units I haven't seen or heard reported that there is a heck of a lot of difference between the two in terms of recovery. Plants that have conducted these types of trials also aren't going to publish, because the vendor on the "losing" side isn't going to be happy. You have had this opportunity - and probably find the same that I have heard anecdotally - no real difference in metallurgical performance, the important difference is in the maintenance issues, availability and service from the vendors - which can differ depending on the company's relationship with the vendor, and the local support team.

If you have run the two versions together, and if you haven't already, ask the maintenance guys which one was easier to maintain, who they had better service from, which one had higher operating hours. It is probably of considerably more value to have a machine that is more available than any debatable metallurgical recovery difference.

David
1 year ago
David 1 year ago

Thank for this Gabriel. This makes for a very interesting discussion!

Some 10 + years ago, I witnessed a side by side plant comparison at an operating mine. A 3rd party metallurgical laboratory was used to monitor and perform the evaluation and avoid any bias.

The trials involved a side by side comparison of two enhanced gravity concentration devices, of approximately the same rated capacity, which were supplied by Falcon Concentrators and Knelson Concentrators.  The performance characteristics of these units were compared on a process stream taken from within the primary grinding circuit

For that specific situation, it was apparent that the Falcon concentrator tended to produce somewhat coarser sized, and lower grade concentrates, than those generated by the Knelson unit: Overall however, gold capture per cycle of operation was almost identical.

Falcon VS Knelson pretty much performed the same.

The cumulative gold distribution in the gravity concentrates were identical for Falcon and Knelson units.

There might be specific technical situations/applications where Falcon wins over Knelson OR Knelson wins over Falcon. I do not know.

Maybe others here have valuable experience to share and add to this.

For now, I would ask myself: 

  1. Is there a large price difference between Falcon VS Knelson Concentrators where you are?
  2. Who offers the best support/service?
  3. Do you have any coarse gold or free in your final tails?

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Gabriel
1 year ago
Gabriel 1 year ago

Thank you all for answers. We will do a good discussion on the topic.
The price difference is low, a small advantage for the Falcon.
Our historical maintenance is to have some balance problems with the Falcon, but I believe that because of the age of the equipment.
Our ore have fine gold, tomorrow will post the distribution the grade by size.
I believe that the question of supplier representatives will not be a problem.
Someone have serious maintenance problems with this equipments?

Modine96069
1 year ago

Gabriel, a Knelson installed at the Sansu Sulphide Treatment Plant (Ashanti Goldfields, Obuasi) in 1995/1996 had a design fault in thT the drive shaft bearings were spaced too close together and subject to unnececessary stress and frequent failures. This information was relayed and demonstrated to the Knelson representative and I believe this fault has been rectified

David
1 year ago
David 1 year ago

Here are some Knelson papers http://knelsongravity.xplorex.com/page423.htm

Look up Steve McAlister (the father of Falconshttp://www.seprosystems.com/sepro-mineral-systems-executive-team

Falcons are believed to be better machines "mechanically" for Engineering is McAlister's background.

Also see An Introduction to Centrifugal Concentrators

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Jorge Quintanilla
10 months ago
Jorge Quintanilla 10 months ago

Many years ago I was involved in a technical comparission between Falcon and Knelson. In that particular case, the winner was Falcon , I don´t know, may be in other mines is different.

I have a personal theory. The most important for gold concentration is the fluidization zone.
It is assumed that due to water ingress this area allows the heavier material may enter to the deeper zone of the fluidized bed where the water comes out. However, if you have a very rich mineral which can visually see gold, even the finest gold, You can see that gold will be in the outer layer of the fluidized bed and for some reason fails to go to the bottom as It supposed must to be. I could not define the reason but this can be viewed in laboratory too.
Now, beyond the difference in the number of channels and volume of concentrate which can be obtained from both concentrators, the biggest difference seems to me that is in the form of work, the Knelson has rubber cushioning stop equipment, instead the falcon is virtually no shock absorption.
I think When Knelson shuts down loses part of concentrate gold from the outer layer of the fluidized bed, which in the falcon does not occur because the stop has no damping.

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