Characterisation and Pre-concentration of Chromite Values from Plant Tailings Using Floatex Density Separator

C. Raghu Kumar, Sunil Tripathy, D.S. Rao

Mineralogy Dept., IMMT, Bhubaneswar, India.
R&D Department, TATA Steel Limited, Jamshedpur, India.

DOI: 10.4236/jmmce.2009.85033                

Abstract

Classification is a method of separation of fines from coarse particles and also lighter particles from heavier particles. The conventional classifiers, such as, hydrocyclone or mechanical classifiers, decreases the efficiency of the grinding and concentration circuits due to their imperfect separation. In the process of improving the efficiency of classification, a device that has been gaining popularity in recent years is the teeter-bed or hindered-bed separator such as Floatex density separator. Generally for processing chromite ores, different types of gravity methods are employed after crushing, grinding followed by classification. The Tata Steel Chrome Ore Beneficiation (COB) plant is generating 50 tph of tailings assaying 17% Cr₂O₃. A critical review on practice of the plant operating personnel is concerned in the grade-recovery characteristics of unit operations. But separation insight and influence of different operating and process parameters are essential to understand and control the process. The objective of the present investigation was to study the effect of the important operating variables on floatex density separator and preconcentration of COB plant tailings for the further beneficiation process and found that significant removal of iron bearing mineral such as goethite and silica is possible using FDS in a single stage operation. The maximum of 83% recovery of chromite is possible with 22 to 23% Cr₂O₃ content and thus obtained FDS underflow is suitable for flotation circuit. A low teeter water flow rate with a high bed pressure removes iron bearing mineral like goethite efficiently in an FDS.

Keywords

Hindered settling, Floatex density separator, Classification and Chromite plant tailings.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Heiskanen, K., 1993, Particle Classification, Chapman and Hall, London.
[2]	De Kok, S.K., 1975, “Fine sizing in milling circuits.” Journal of SAIMM, October, pp 83-86.
[3]	Heiskanen, K., 1979, “Two stage classification.” World Mining, Vol. 32, pp 44-46.
[4]	Hukki, R.T., and Heiskanen, K., 1981, ”Two stage hydrallic classification: A report on industrial application.” 110th Annual AIME meeting, Chicago.
[5]	Lynch, A.J., 1977, Mineral crushing and grinding circuits, Elsevier, New York.
[6]	Luckie, P., Hogg, R., and Schaller, R., 1980, “A review of two fine particle processing unit operations – Classification and Mixing.” Fine particle processing, Somasundaran (Ed),Vol.1, pp 167-180.
[7]	Rogers, R.S.C., Hukki, A.M.., Steiner, G.J., and Arterburn, R.A., 1981, “An evaluation of the use of two vs. one stage hydro cyclones in a pilot scale ball mill.” 110th Annual AIME meeting, Chicago.
[8]	Guney A., Onal G., and Atmaca T., 2001, New aspect of chromite gravity tailings reprocessings, Vol. 14, pp 1527-1530.
[9]	Rao S.M., Chandrakala K., Kapure G., Nath G., and Rao N.D., 2006, “Recovery of chromite values from chrome ore beneficiation plant tailings.” Tata Search, pp 59-64.
[10]	Guney A., Sirkesi A. A., Gurkan V., and Onal G., 1996, “The recovery of chromite fines from the tailings of Uckopru chromium plant using HIWMS.” Changing scopes in mineral processing, pp 149-154.
[11]	Sarkar. B., Das A, and Mehrotra S.P., 2008, “Study of separation features in floatex density separator for cleaning fine coal.” Int. J. Miner. Process., Vol. 86, pp. 40–49.
[12]	Richardson J. F., and Zaki W. N., 1954, Trans. Inst. Chem. Eng., Vol. 32, pp. 35.