size fractionating

Maybe you need to think out of the box with this kind of stuff.

How about using friction of the particles when suspended in air or even in liquid. When particles are bigger they will have a different interaction characteristic with its surrounding media. I am no expert on this field but I would have thought it could be used to divide the particles by size that way. Why not look it up in google by combining micron separation with aero dynamics or hydro dynamics?

Have you looked at a cyclone? Failing that maybe something can be done with a tube of Bernoulli to cause different speeds of the particles.

In continuous mineral processing of slurries, hydrocyclones are often used for particle segregration. Chances are that if sekenber can determine the Reynold's number of their celloluse fibers falling in whatever medium they have them in, they will be able to predict what speed and size of hydrocyclone to use in separation.

There you go, I knew that somebody would know more about it than I do. I am sure it will prove possible but if it is financially viable that may be an entirely different matter altogether.

The original poster mentions a kilogram of the stuff. Is that all he is looking to seperate????? If so he or she needs to think again.

Although we are not interested in that subject, but we -at least- need to understand the problem.

Sorry dear Abdel Halim Galala, you have lost me!

Can you explain what you mean with your statement or question?

Sorry dear case491,

I mean with "not interesting" that the process is unknown w.r.t. me, may be my expression in english was not precise. But the meaning of my statement is : I'm interesting to understand and share yours.

Ok I see now.

If you read post 3 and search for his suggestion, I am sure it will all be explained. I am sure you know that cyclones work on the principle of diminishing air speed closer to the wall of the round separator column. The dust that is in the air will slow down as it travels to the edge and will get to a speed that it falls down out of the rotating air it is traveling with. This is caught at the bottom and so you separate the dust out of the air. Different dust particles with different sizes will fall out of the air at different speeds so you could theoretically separate them.

Hydro cyclone must work according to a similar principle but now it is a suspension of the parts in a fluid.

Sounds simple but I am sure it can give you a headache if you need it to work and it does not

Yes case491, that is good clarification,

But for your statement "If you read post 3 and search for his suggestion", I'd like you to know that my post #2 which subjected to your comment was send before applying or seeing post #3 by Ben Bonsens.

sorry, I missed that little but important fact.

Still hope you liked it though and that it was helpfull.

Sorry again.

OK case491, and you are welcome.

Dear Case 491,

I am not sure that I understood your explanation for the cyclone function. I am aware that my knowledge is limited but as far as I know a cyclone uses the centrifugal force acting on a particle in a circular movement. The conical part is an accelerating part since the radius decreases and the tangential speed was given by the cylindrical part. Since the centrifugal acceleration is v^2/R an R decrease will increase the acceleration and related force. The medium offers to the particle a resistance proportional to a geometric factor, its relative speed with respect to the fluid and the viscosity of the last. Due to this the particles move radially to the exterior and at the bottom where the flux is changing drastically its direction only the "cleaned" fluid goes out. The particles continue to "fall" down in the bottom box.

I may be wrong but I designed years ago such separators for earth drilling and they worked, at least at that time, as I described above.

Please explain how they work now I always ready to learn more.

Thank you

Nickname.