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## Journal of the Southern African Institute of Mining and Metallurgy

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*versão On-line* ISSN 2411-9717

*versão impressa* ISSN 0038-223X

### J. S. Afr. Inst. Min. Metall. vol.110 no.6 Johannesburg Jun. 2010

**TRANSACTION PAPER**

**A comparison between the duplicate series analysis method and the heterogeneity test as methods for calculating the sampling constants, K and alpha**

**R.C.A. Minnitt ^{I}; W. Assibey-Bonsu^{II}**

^{I}School of Mining Engineering, University of the Witwatersrand, Johannesburg, South Africa

^{II}Gold Fields Limited, Perth

**SYNOPSIS**

The compilation of the sampling nomogram is an essential tool in the optimization of a sampling protocol and allows the operator to track the change in relative variance of the sampling error (the Fundamental sampling error) during steps of comminution and mass reduction in the process of recovery of the aliquot for analysis. The data required for the compilation of the nomogram are centred on the sampling constant *K *and the exponent, alpha (α) of the nominal fragment size. Five methods for establishing *K *have been identified, but two of them, the duplicate sampling analysis method and the heterogeneity test method purport to provide such constant. The step by step procedure for each of these two methods was examined using broken ores from three mines, Mponeng mine, Kloof mine, and Lily mine. Two of these mines (Mponeng and Kloof) are typical Witwatersrand-type gold mines, and the third is an Archaean-type shear related gold deposit situated in the Barberton Greenstone belt. The results suggest that the factor *K *derived using the heterogeneity test is very accurate, but applies only to a single size fraction in the spectrum of comminuted materials. The calculation of gold grain sizes using this method appear to be too small and do not conform with the results from detailed mineralogical studies. The factors *K *and alpha derived using the duplicate series analysis are appropriate for use across a wide spectrum of comminution sizes and also provide realistic gold grain sizes, comparable with the equivalent circular diameter of gold grains identified in mineralogical studies of the ores.

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**References**

1.** **GY, P.M. *Sampling of particulate materials*-*Theory and practice, *2nd Edition, Elsevier, Amsterdam. 1979. 430 p. [ Links ]

2.** **LYMAN, G.J. *Sampling of Particulate Materials Power Point Presentation Workshop*, Porto Alegre, Brazil, 2007, vol. 1, 2007. 174 p. [ Links ]

3.** **PITARD, F.F. Pierre Gy's Theory of Sampling and C.O. Ingamells' Poisson Process Approach, pathways to representative sampling and appropriate industry standards. PhD Thesis, Aalborg University, Esbjerg Campus, Niels Bohrs Vej 8, DK-67 Esberg, Denmark, 2009. [ Links ]

4.** **PITARD, F.F. The Theory and Practice of Sampling, a Short Course given through the Geostatistical Association of Southern Africa, in the School of Mining Engineering, University of the Witwatersrand, as part of the GDE Programme. 2005. [ Links ]

5.** **PITARD, F.F. Effects of residual variances on the estimation of the variance of the Fundamental Error. C*hemometrics and Intelligent Laboratory** Systems, *vol. 74, 2004. pp. 149-164. [ Links ]

6.** **FRANCOIS-BONGARCON, D. Sampling in the Minerals Industry-The Theory and Practice, a Short Course given through the Geostatistical Association of Southern Africa, in the School of Mining Engineering, University of the Witwatersrand, as part of the GDE Programme. April-May 1995. [ Links ]

7.** **GY, PIERRE. Sampling of discrete materials-a new introduction to the theory of sampling I Qualitative Approach. *Chemometrics and Intelligent** Laboratory Systems, *vol. 74, 2004. pp. 7-24. [ Links ]

8.** **PITARD, F.F. A short course on the theory, predictability and economic consequences of the *in situ *Nugget Effect. *Third World Conference on** Sampling and Blending*. October 22, 2007. 45 p. [ Links ]

9. FRANCOIS-BONGARÇON, D. Extensions to the Demonstration of Gy's Formula. January, 1998. [ Links ]

10.** **BECKER, A.D.J. Sampling in the Mining Industry I (Theory). A Gencor inhouse report on sampling theory and practice. 1995. 44 pp. [ Links ]

11.** **ASSIBEY-BONSU, W. Summary of present knowledge on the representative sampling of ore in the mining industry. *The Journal of South African** Institute of Mining and Metallurgy*, November 1996. pp. 289-293. [ Links ]

12.** **MINNITT, R.C.A., RICE, P., and SPANENGBERG, C. Part 2: Experimental calibration of sampling parameters *K *and alpha for Gy's formula by the sampling tree method. *Journal of the Southern African Institute of Mining** and Metallurgy, *vol. 107, August 2007. pp. 513-518. [ Links ]

13. PETERSEN, L., DAHL, C.K., and ESBENSEN, K.H. Representative mass reduction in sampling-a critical survey of techniques and hardware: Chemometrics and intelligent Laboratory Systems, Volume 74, Issue 1. 28 November 2004. Special Issue: 50 years of Pierre Gy's Theory of Sampling* Proceedings: First World Conference on Sampling and Blending *(WCSB1). pp. 95-114. [ Links ]

14.** **FRANCOIS-BONGARCON, D. Sampling in the mineral industry, Theory and Practice. Course presented in Johannesburg by Mineral Resources Development Consultants, California, USA. 1995. [ Links ]

15.** **COETZEE, L.L. A General Mineralogical and Gold Deportment Study On Six Gold Bearing Ore Samples from the Kloof Gold Mine. Mineralogical Report No: Min 1207/213, Proposal number: 07/386 for and on behalf of Gold Fields Ltd.-Kloof Gold Mine 2 April 2008. SGS Lakefield Research Africa (Pty) Ltd 58 Melville Street, Booysens, Johannesburg 2091. P.O Box 82582, Southdale 2135, South Africa. 2008. 120 p. [ Links ]

16.** **MAGRI, E.J.M. Some experiences in Heterogeneity Tests and Mine Sampling. *Third World Conference on Sampling and Blending Proceedings* WCSB3. 23-25th October 2007. Sheraton Hotel, Port Allegre, Brazil. Publishers, Joao Felipe Costa and Jiar Koppe. 2007. pp. 329-351. [ Links ]

17.** **HOLMES, R.J. Correct sampling and measurement-the foundation of accurate metallurgical accounting. *Chemometrics and Intelligent** Laboratory Systems*, vol. 74, 2004. pp. 71-83. [ Links ]

18.** **FRANCOIS-BONGARCON, D. and GY, P. The Most Common Error in Applying 'Gy's Formula' in the Theory of Mineral Sampling, and the History of the Liberation Factor, *Mineral Resource and Ore Reserve Estimation-The** AusIMM Guide to Good Practice*. A.C. Edwards (ed.), The Australasian Institute of Mining and Metallurgy: Melbourne. 2001. pp. 67-72 [ Links ]