Special Issue "Sampling across the Mine Value Chain"

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Metallurgy".

Deadline for manuscript submissions: 20 December 2019.

Special Issue Editors

Dr. Simon Dominy
E-Mail Website
Guest Editor
Camborne School of Mines, University of Exeter, Penryn, Cornwall TR10 9FE, UK
Interests: economic geology; sampling/theory of sampling; reserve estimation/evaluation; geometallurgy; mining geology; narrow vein mining; mineral processing
Special Issues and Collections in MDPI journals
Prof. Hylke Glass
E-Mail Website
Guest Editor
Camborne School of Mines, University of Exeter, Penryn, Cornwall TR10 9FE, UK
Interests: sampling/theory of sampling; geometallurgy; geostatistics; sensor-based mineral sorting; selective leaching; metal bio-accessibility; post-mining revegetation and terra-greening
Prof. Kim Esbensen
E-Mail Website
Guest Editor
1. KHE Consult, Aldersrogade 8, 2. sal, 2100 Copenhagen Ø, Denmark
2. Geological Survey of Denmark and Greenland (GEUS), Oester Voldgade 10, 1350 Copenhagen C, Denmark
Interests: sampling/theory of sampling; geochemistry/geoanalysis; process analytical technology; multivariate data analysis; chemometrics

Special Issue Information

Dear Colleagues,

Sampling is a critical component throughout the Mine Value Chain; it includes the sampling of both in situ and broken material for exploration, resource and grade control, geoenvironmental, metallurgical and geometallurgical purposes. The data produced must be fit-for-purpose to contribute to Mineral Resources/Ore Reserves reported in accordance with The 2012 JORC Code 2012 or other international reporting codes. Quality assurance/quality control is critical to maintain data integrity through documented procedures, sample security, and monitoring of precision, accuracy and contamination. Samples are their associated assays are key inputs into important decisions throughout the Mine Value Chain.

The Theory of Sampling (TOS) was developed in the 1950s by the late Dr. Pierre Gy to improve sampling within the mining industry (though it has far wider applications). It defines and provides guidelines for the reduction of sampling errors, which may lead to uncertainty and create an overall measurement error. TOS attempts to break down this error into a series of contributions along the sampling value chain (e.g., the planning to assay-measurement process). Errors are additive throughout the sampling process and generate both monetary and intangible losses. The aim is to collect representative samples to accurately describe the material in question.

Despite the wealth of knowledge available on correct sampling principles, it is surprising how little attention and resources are often dedicated to collecting representative samples. Often, practitioners appear to be satisfied as long as some material is collected and delivered to the laboratory for analysis. Yet, unless the samples are representative, the whole measurement process is flawed at the outset and no amount of re-analysis can fix the problem. Consequently, companies stand to lose millions of dollars in terms of poor investment decisions, wasted resources, poor plant performance, poor product quality and income from product sales. Sampling, therefore, needs to be given the attention it deserves to ensure that the samples extracted are representative so that meaningful decisions can be made based on their analyses.

Dr. Simon Dominy
Prof. Hylke Glass
Prof. Kim Esbensen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Theory of Sampling
  • Exploration sampling
  • Sampling for resource/reserve estimation
  • Mine grade control sampling
  • Geoenvironmental sampling
  • Metallurgical and geometallurgical sampling
  • Sample preparation, testing and assaying
  • Quality assurance/quality control
  • Mathematical modelling of sampling systems
  • New developments in sampling, sample preparation and blending equipment
  • Future technologies
  • Case studies

Published Papers (3 papers)

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Research

Open AccessArticle
Integrating the Theory of Sampling into Underground Mine Grade Control Strategies: Case Studies from Gold Operations
Minerals 2019, 9(4), 238; https://doi.org/10.3390/min9040238 - 17 Apr 2019
Cited by 1
Abstract
Grade control aims to deliver adequately defined tonnes of ore to the process plant. The foundation of any grade control programme is collecting high-quality samples within a geological context. The requirement for quality samples has long been recognised, in that these should be [...] Read more.
Grade control aims to deliver adequately defined tonnes of ore to the process plant. The foundation of any grade control programme is collecting high-quality samples within a geological context. The requirement for quality samples has long been recognised, in that these should be representative and fit-for-purpose. Correct application of the Theory of Sampling reduces sampling errors across the grade control process, in which errors can propagate from sample collection through sample preparation to assay results. This contribution presents three case studies which are based on coarse gold-dominated orebodies. These illustrate the challenges and potential solutions to achieve representative sampling and build on the content of a previous publication. Solutions ranging from bulk samples processed through a plant to whole-core sampling and assaying using bulk leaching, are discussed. These approaches account for the nature of the mineralisation, where extreme gold particle-clustering effects render the analysis of small-scale samples highly unrepresentative. Furthermore, the analysis of chip samples, which generally yield a positive bias due to over-sampling of quartz vein material, is discussed. Full article
(This article belongs to the Special Issue Sampling across the Mine Value Chain)
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Open AccessArticle
Variographic Assessment of Total Process Measurement System Performance for a Complete Ore-to-Shipping Value Chain
Minerals 2018, 8(7), 310; https://doi.org/10.3390/min8070310 - 23 Jul 2018
Abstract
Variographic characterisation has been shown to be a powerful tool to assess the performance of process measurement systems, using existing process data. Variogram interpretation enables decomposition of variabilities stemming from the process and measurement system, respectively, allowing to determine if measurements are able [...] Read more.
Variographic characterisation has been shown to be a powerful tool to assess the performance of process measurement systems, using existing process data. Variogram interpretation enables decomposition of variabilities stemming from the process and measurement system, respectively, allowing to determine if measurements are able to describe the true process variability with sufficient resolution. This study evaluated 14 critical sampling locations, covering a total of 34 separate measurement systems, along the full processing value chain at Luossavaara Kiirunavaara limited company (LKAB), Sweden. A majority of the variograms show low sill levels, indicating that many sub-processes are well controlled. Many also show low nugget effect, indicating satisfactory measurement systems. However, some notable exceptions were observed, pointing to systems in the need of improvement. Even if some of these were previously recognized internally at LKAB, the use of variographic characterisation provide objective and numerical evidence of measurement system performance. The study also showed some unexpected results, for example that slurry shark-fin and spear sampling show acceptable variogram characteristics for the present materials, despite the associated incorrect sampling errors. On the other hand, the results support previous conclusions indicating that manual sampling and cross belt hammer samplers are leading to unacceptably large sampling errors and should be abandoned. Such specific findings underline the strength of comprehensive empirical studies. Based on the present compilation of results, it is possible to conduct rational enquiry of all evaluated measurement systems, enabling objective prioritization of where improvement efforts will have the largest cost–benefit effect. Full article
(This article belongs to the Special Issue Sampling across the Mine Value Chain)
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Open AccessArticle
Integrating the Theory of Sampling into Underground Mine Grade Control Strategies
Minerals 2018, 8(6), 232; https://doi.org/10.3390/min8060232 - 29 May 2018
Cited by 5
Abstract
Grade control in underground mines aims to deliver quality tonnes to the process plant via the accurate definition of ore and waste. It comprises a decision-making process including data collection and interpretation; local estimation; development and mining supervision; ore and waste destination tracking; [...] Read more.
Grade control in underground mines aims to deliver quality tonnes to the process plant via the accurate definition of ore and waste. It comprises a decision-making process including data collection and interpretation; local estimation; development and mining supervision; ore and waste destination tracking; and stockpile management. The foundation of any grade control programme is that of high-quality samples collected in a geological context. The requirement for quality samples has long been recognised, where they should be representative and fit-for-purpose. Once a sampling error is introduced, it propagates through all subsequent processes contributing to data uncertainty, which leads to poor decisions and financial loss. Proper application of the Theory of Sampling reduces errors during sample collection, preparation, and assaying. To achieve quality, sampling techniques must minimise delimitation, extraction, and preparation errors. Underground sampling methods include linear (chip and channel), grab (broken rock), and drill-based samples. Grade control staff should be well-trained and motivated, and operating staff should understand the critical need for grade control. Sampling must always be undertaken with a strong focus on safety and alternatives sought if the risk to humans is high. A quality control/quality assurance programme must be implemented, particularly when samples contribute to a reserve estimate. This paper assesses grade control sampling with emphasis on underground gold operations and presents recommendations for optimal practice through the application of the Theory of Sampling. Full article
(This article belongs to the Special Issue Sampling across the Mine Value Chain)
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