For such small particles, a sonic sifter like this one :

http://www.endecotts.com/products/sieve-shakers/sonic-sifter/product-specifications/

can separate them into many fractions of different sizes.

Alain

Both froth-based flotation and elutriation could be considered, since the particles size, shape, and density, jointly influence the performance of these methods.

Thank you so much to all of you for your responses  but I just want to separate out these particles on the basis of their sphericity means how much % these particles are approx. sphere.

{A}FILL/ CLICK:

Experimental determination of sphericity of fly ash particles:

FIND:

[PDF] Experimental determination of Scattering matrix of------

CLICK/FIND:

Journal Of Geophysical Resarch,Vol.106. NoD19; 22833-22844(2001)

{B}International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Title: Morphology and Selected Properties of Fly Ash

Author(s): P. K. Rohatgi, P. Huang, R. Guo, B. N. Keshavaram, and D. Golden

Publication: Special Publication

aci

Volume: 153

Issue:

Appears on pages(s): 459-478[1995]

Abstract:

A new variety of applications are being found for fly ash. It is increasingly important to determine the structural properties of fly ash particles, especially for increasing use in composites, such as polymer matrix and cast metal matrix composites. In this paper, selected properties of precipitator fly ash and cenosphere fly ash were directly measured; other properties were indirectly estimated from the experimental measurements on the properties of composites containing fly ash. {{{The properties studied included sphericity of fly ash particles, wall thickness, the ratio of wall thickness to diameter, and modulus.}}} The data generated on properties of fly ash have been compared with other filler or reinforcement materials, such as glass microspheres, Al 2O 3 , SiO 2, and SiC particles. The results show that the deviation of cenospheres from sphericity is virtually independent of diameter. The ratio of wall thickness to diameter of cenospheres is about 0.1 and tends to decrease with increasing particle diameter. The calculated values of effective modulus of fly ash from the property measurements on metal matrix-fly ash composites are in the range of 140 to 310 GPa, which are of the same order of magnitude as of general ceramics and glasses. The morphology of precipitator and cenosphere fly ash particles studied using scanning electron microscope is discussed. The implications of the morphology and properties of fly ash on its utilization, especially in micro and macro composites, including cements, are also discussed.

Journal of Geophysical Research; Vol106; No:D19; Pages:22833- 22844[2001]

HOW TO REACH?

FILL/ CLICK:

Determining sphericity of fly ash particles

Click:

Morphology and Selected Properties of Fly Ash - American ...

www.concrete.org/Publications/GetArticle.aspx?m=icap&pubID=1083

by PK Rohatgi - ‎1995 - ‎Cited by 7 - ‎Related articles

seems that for your particles use of a scanner or more sophisticated a CamSizer like instrument would be the ideal solution.

If sphericity in addition to size is required, then devices such as Zetasizers supplied by Micromeritics or Malvern allow to do that. The typical range of size that can be studied by the corresponding methods (DLS or DWS) is 0.3 nm to 10 µm.

Alain

I meant 1 µm and larger.