IJE TRANSACTIONS B: Applications Vol. 15, No. 2 (July 2002) 191-203   

downloaded Downloaded: 71   viewed Viewed: 1800

A. A. Rahmani

Department of Mining Engineering, Imam Khomeini International University
Qazvin, I.R. Iran, aarahmani@yahoo.com
( Received: October 17, 2000 – Accepted in Revised Form: December 31, 2001 )

Abstract    Selective flocculation has long been suggested as a method for the treatment of ultra-fine particles typical of which are those produced in a de-sliming process ahead of flotation. In this paper the results of the coal de-mineralization, using synthetic polyacrylamide polymers, are presented. A prescreening test on the suitability of the polymers using Run-Of-Mine (R.O.M.) coal and artificial mixtures of Shirebrook coal and shale the floe settling rates and supernatant clarity of the suspension was carried out and three polymers. Floe Aid 202 (medium anionic). Floe Aid 204 (high anionic) and Polyethylene oxide (P.E.O.) (non- ionic) were employed in subsequent experimental work. The effectiveness of the polymers was established by carrying out settling rate tests using polymers dosages between 0.00025 to 0.0075 g/25g feed and at various suspension pH values. P.E.O. showed significant differences in the flocculation of coal and shale. The results concerning polymers FA 202 and FA 204 are not discussed. Slurry pH, dispersant concentration and polymer dosages were examined and are discussed. Shale entrapment was believed to be due to three reasons. Firstly the mineral particles not fully liberated from the coal structure. This could be infered from the S.E.M. micrographs. Secondly, once coal floes have been formed, they become larger in size, and on settling collect the much smaller mineral particles, beneath themselves, to the bottom of the container. And thirdly polymers may possess a weak affinity for the shale surface. 


Keywords    Selective Flocculation, De-Sliming, Polymers, Settling Rate



1. Attia, Y. A., Conkle, H. N. and Krishnan, S. V., "Selective Flocculation Coal Cleaning for Coal Slurry Preparation", Proceedings of the 6th Int. Symp. On Coal Slurry Combustion and Tech., Orlando, (1984). 571-581.

2. Haseman, J. F., "Selective Flocculation of Colloidal Phosphate Ore in the Presence of Clay", U.S. Patent 2.660.303, (Nov. 24, 1953).

3. Usoni, L. G., Rinelli, G. and Marabini, A. M., "Selective Properties of Flocculants and Possibilities of Their Use in Flotation of Fine Minerals", Proc. 8th Int. Miner. Process Congr., Leningrad, U.S.S.R, (1968), Paper D13, 14-21.

4. Fromer, D. W. and Colombo, A. F., "Process for Improved Flotation Treatment of Iron Ores by Selective Flocculation", U.S. Patent3.29i.780, (Dec.20, 1966).

5. Hucko, R. E., "Beneficiation of Coal by Selective Flocculation, a Laboratory Study", U.S. Dept. of Interior, Bureau of Mines, Ref. No. 8234, (1977), 1-4.

6. Blagov, I. S., "Discussion of a Paper on Flocculation of Minerals and Carbon Suspensions by Polymers: By I. S. Blagov and Others", Proc. 9th Int. Mier. Procces Congress, Prague, Czechoslovakia, (1970), 166-173.

7. Blaschke, Z., "Benefieiation of Coal Fines by Selective Flocclation", 7th Int. Coal Preparation Congress, (May 1976), Paper F2, 1-16.

8. Brookes, G. F., Littlefair, M. J., Spencer, L. and Abdulrahman, A. A., "The Selective Flocculation of Coal/Shale Mixtures U sing Commercial and Modified Polyacrylamide Polymers", XIV Int. Mineral Processing Congress, Toronto, Canada,(0ct. 1982), 17-23.

9. Bajor, 0, and Trass, 0., "Modified Oil Agglomeration Process for Coal Beneficiation; In Mineral Matter Liberation by Fine Grinding with Szego Mill", The Canadian J. of Chem. Eng., Vol. 66, (April 1988), 282-290.

10. Singh, J. and Singh, M. N., "Settling Rates of Polymeric Flocculants", Ind. J. Tech., 17, (7), (Feb.1979), 283-284.

11. Sworska, A., et at., "Flocculation of the Syncrude Fine Tailings Part II. Effect of Hydrodynamic Conditions", Int. J. Miner. Process, 60, (2000), 153-161.

12. Karapinar, N., Ekmekci, Z. and Demiral, H.., "Separation of Quartz from Clay Minerals by Selective Flocculation in Progress in Mineral Pro. Tech.", Demirel + Ersayin Eds., Publisher A. A. Ballcema, Rotterdam, ISBN 9054105135, (1994), 219-226.

13. Hogg, R., "Polymers in Mineral Processing", Proc. 3rd UBC McGill Int. Symp., Metallurgical Society of CIM (Ed. J. S. Laskowski), Quebec City, (1999), 3-17.



International Journal of Engineering
E-mail: office@ije.ir
Web Site: http://www.ije.ir