JOURNAL PAPER

Nugget effect, artificial or natural?

P.C. Carrasco

Technical Group, Codelco,Chile

SYNOPSIS

Knowing the origin of the relevant and irrelevant components of the nugget effect is essential to optimize the process under study. This paper describes the causes of the nugget effect and, its dependency on the sample support, sampling density, and on the QA/QC procedures. Several examples of natural and 'human' nugget effect are given. A method to estimate the magnitude of the relevant and irrelevant components is suggested. Finally, the economic consequences of misunderstanding the nugget effect are analysed.

“Full text available only in PDF format”

References

1. CHILES, J. P. and DELFINER, P. Geostatistics: Modeling Spatial Uncertainty. Wiley Series in Probability and Statistics. John Wiley & Sons, Inc. 1999. p. 695.         [ Links ]

2. DAVID, M. Geostatistical ore reserve estimation. Elsevier Science Ltd, Developments in Geomathematics, vol. 2. 1977. p. 384.         [ Links ]

3. MATHERON, G. La Théorie Des Variables Régionalisées et Ses Applications. Les Cahiers du Centre de Morphologie Mathématique De Fontainebleu. Fascicule 5. Ecole Nationale Supérieur des Mines de Paris. France. 1970.         [ Links ]

4. PITARD, F. Pierre Gy's Sampling Theory and Sampling Practice. Heterogeneity, Sampling Correctness, and Statistical Process Control. CRC Press, 1993. p. 488.         [ Links ]

5. GY PIERRE, L'Echantillonnage des minerais en Vrac. vol. 1. Revue de l Industrie Minérale, St Etienne, France. Numéro Spécial. 15 Janvier 1967.         [ Links ]

6. GY PIERRE, L'Echantillonnage des minerais en Vrac. vol. 2. Revue de l Industrie Minérale, St Etienne, France. Numéro Spécial. 15 Septembre 1971.         [ Links ]

7. GY, PIERRE. Sampling of Particulate Materials Theory and Practice. First edition (1979) second revised edition (1982). Elsevier, Amsterdam xvii. 1979. p. 431.         [ Links ]

8. JOURNEL, A.G. and HUIJBREGTS, C.J. Mining Geostatistics. Academic Press, New York, 1978. p. 600.         [ Links ]

9. CARRASCO, P., CARRASCO, P., and JARA, E. The economic impact of correct sampling and analysis practices in the copper industry. Chemometrics and Intelligent Laboratory Systems, vol. 74, 2004. Elsevier Scientific Publications. pp. 209-213.         [ Links ]

10. CARRASCO, P., WILKE, A., JARA, E., and SUAREZ, E. Some applications of statistics and geostatistics to the sampling of a big cooper tail stream. Third world conference on sampling and blending. Porto Alegre, Brazil. 2007. p. 352-366        [ Links ]