Genotipo

Introducción al Muestreo
Minero
por
Marco Antonio Alfaro Sironvalle

Santiago, Chile, 2002

Instituto de Ingenieros de Minas de Chile.
Encomenderos 260, Of. 31. Tel (56-2) 2461615, Fax 2466387.
E-Mail: instituto@iimch.cl
Web: http://www.iimch.cl
Santiago, Chile, 2002.

Es Propiedad.
Prohibida la reproducción parcial o total sin autorización del autor.

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Preface

Is there asingle important decision made on a mining project that is not in a way or
another, directly or indirectly based on some kind of assayed grade, or in other
terms on a mineral sample? And who, in the end, is responsible for the devastating
consequences of taking bad samples?
It clearly is a subject of utmost importance that Dr. Marco Alfaro has decided to
bring to his audience in this simple,yet fundamental leaflet, which is directed not
only to technical professionals of the mining industry, but also to those who
manage them and bear the ultimate responsibility for the results and
consequences of mineral sampling. In this piece of work, Dr. Alfaro genuinely
makes justice to the simplicity of sampling theory, and to the many services it
renders and has rendered the industry overseveral decades of applications.
Like in many a discipline, however, there is Sampling and ‘Sampling’, good and
poor applications, enlightenment and ignorance, science and witchcraft. Practical
implementations have kept improving, but have also suffered through many
avatars, not all consistent with its eminently scientific approach. Erroneous
sampling equipment and experimental procedures,incorrect application models
and formulae, based on a highly commercial but appallingly arbitrary modus
operandi, have made their way into our service and equipment markets, and are
currently offered to the non-discerning professional. The utmost critical sense and
prudence must be exercised.
It is to Dr. Alfaro’s credit to have presented in a simple and short publication all the
tools thatwill help the professional of the industry, as well as the managers and
directors who are committed to the success of mining projects, tell the good
from the bad, and not fall prey to ‘imitation sampling theory’ which plagues our
plants, our mines, and even some of our ‘consultants’ calculations.
As active devotees to the future and growth of genuine sampling theory, we feel
indebted to Dr.Alfaro and thank him very much for this commendable effort.

Pierre Gy & Dominique Francois-Bongarcon
Sampling Associates

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Prólogo

Estimado lector, he decidido publicar en el lenguaje más simple posible una
introducción a la Teoría del Muestreo Minero, para ello, basado en mi experiencia
docente, he considerado fundamental incluir el máximo de gráficos.
En algunas ocasiones elmaterial presentado corresponde a minas conocidas, he
omitido sus nombres, por razones de discreción minera.
Agradezco sinceramente la ayuda, consejos y apoyo de los Doctores Pierre Gy y
Dominique Francois-Bongarcon. Agradezco también a Ana María por su apoyo y
consejos.
Estimado lector, agradeceré contactarme ante cualquier duda, comentario o
sugerencia. Juntos mejoraremos futuras ediciones dellibro.

Marco Antonio Alfaro
Enero, 2002.

A
Ana María, Marco y Sebastián.

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TEMARIO.

I. Introducción e Importancia del muestreo de minerales.

5

II. Conceptos importantes en Teoría del Muestreo. Problema principal.

8

III. El Muestreo Estadístico. Ecuaciones.

14

IV. Consideraciones prácticas para el muestreo de minerales.

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V. Muestreo de flujos de mineralesen movimiento.

40

VI. Tipos especiales de muestreo minero.

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VII. El Error Fundamental del Muestreo. Teoría de Pierre Gy.

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VIII. Bibliografía.

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Anexo 1. Tabla de números aleatorios.

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Anexo 2. El Profesor Pierre Maurice Gy.

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Anexo 3. Sesgos generados por muestreo y análisis.

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Anexo 4. Ejemplos de errores de muestreo importantes.

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Anexo...