Dear Dr. Sharma,

To distinguish between GGBFS and Iron slag, chemical composition analysis is most important. GGBFS contains alumina as major component after CaO while iron is the major component in iron slag.

Generally GGBFS is white to greyish in color while Iron slag is grey to gyeyish black in color. 

check the links for GGBFS and Iron slag pictures and their composition.

Kunal

https://www.google.co.in/search?q=Iron+slag&sa=X&biw=1366&bih=643&tbm=isch&tbo=u&source=univ&ei=ScSNVLbUBImLuATzo4DYBA&ved=0CCkQsAQ

https://www.google.co.in/search?q=GGBS&biw=1366&bih=643&tbm=isch&tbo=u&source=univ&sa=X&ei=8sONVJTTD9GzuATaooBo&ved=0CDUQsAQ

http://www.slg.jp/e/slag/character.html

Ground Granulated Blast Furnace Slag is typically very amorphous, as a result of the rapid cooling caused by granulation. Basic Oxygen Furnace Slag (I supposed this is what you mean by iron slag) is usually crystalline (when not granulated). Therefore, X-ray diffraction (XRD) is a good tool to differentiate the two materials.

Attached are two of my papers where you can find characterization of these two slags.

Article Towards zero-waste mineral carbon sequestration via two-way ...

Article Stabilization of basic oxygen furnace slag by hot-stage carb...

your answer and links helps me allot to distinguish the GGBFS and Iron slag.Thanks to guided me

Can someone guided me about the influence of Basic oxygen furnace slag on compressive strength properties of concrete. is this possible the BOFS containing concrete compressive strength in 7 days is less than normal concrete 

i have sanded you the pictures of slag which i have used.based on that i have concluded that it is a BOF slag ,with this i am also sending you the chemical composition. can somebody conformed by seen this picture and chemical composition whosoever is well known about slag