08924875(01)ooo2&7 Minerals Engineering, Vol. 14, No. 4. pp. 445448,200l 0 2001 Elsevier Science L.td All rights reserved 0892-6875/01B - see front matter TECHNICAL NOTE A FAST DETERMINATION OF Fe%e2* RATIO IN INDUSTRIAL MINERALS A.F. MULABA-BAFUBIANDIq, H. POLLAK”**, M. MASHLAN+, D. JANCIK+ and A. KHOLMETSKII* 4[Technikon Witwatersrand, Faculty of Engineering, School of Process and Mechanical Engineering, Department of Metallurgy, P.O.Box 526, Wits 2050, Johannesburg, South Africa. Email: MulabaBphysnet.phys.wits.ac.za 0 University of the Witwatersrand, Department of Physics, P.O.Box 526, Wits 2050, Johannesburg, South Africa. t Palacky University, Department of Experimental Physics, Svobody 26, 77146 Olomouc, Czech Republic 1: Belorussian State University, Department of Physics, Skoriny Ave 8, Minks, Belarus *Deceased. (Received 18 October 2000; accepted 16 January 2001) ABSTRACT Three-channels data collecting method for the determination of Fe3+/Fe2’ ratio in industrial iron- bearing minerals is proposed using Miissbauer effect spectroscopy. The method has been proved faster (less than $ve minutes) than the conventional collection of fill Miissbauer spectra. Natural Ilmenite, Chromite and Stilpnomelane minerals can be used. The later is used to illustrate the method. 02001 Elsevier Science Ltd. All rights reserved. Keywords Industrial minerals; on-line analysis; process optimisation. INTRODUCTION Fe3+/FeZ+ ratio in raw materials has been one of the crucial criteria in considering or discarding the iron- bearing feeds to the ceramic, paint and cosmetic industries. It has been used as a geothermal indicator for diamond formation in kimberlitic structures [Burns (1993)]. The toxicity of fibrous crocidolite minerals and the coloration of gemstones have been monitored using this Fe3+/Fe2+ ratio [Gulumian et al. (1993)]. Conventional methods for its determination involve the tedious and cumbersome chemical analysis and the recording of the full Mijssbauer effect spectrum of the mineral. Although the determination of ferric to ferrous ratio by the conventional Mossbauer effect technique agrees with results from the wet chemical analysis, relatively long data collection time (4 to 48 hours) is required. This could impede on its on-line industrial utilization. This paper reports on a speedy method for the determination of this ratio. Natural ilmenite, chromite and stilpnomelane minerals can be used. The later is used to illustrate the technique. With an acquisition time of less than five minutes, the ratio Fe3+/Fe2+ is easily determined and a cut-off decision on the quality of the particular iron-bearing raw material, as far as this ratio is concerned, can then be made. 445