- Maintaining the quality Australia–wide
- Assay Program Management – Planning For Quality
- Issues Concerning the Quality of Assay Results
- The Sepon Project – Sampling and Assaying in an Exploration Project
- The Use of Matrix-Matched Standards to Monitor the Quality of Assay Data
- Laboratory Accreditation – A Confidence Framework for Laboratories and their Clients
- An Audit Of Outokumpu Mining Australia’s Quality Control Practices
- Deep Sea Tailing Placement
- Unrealistic Expectations of Assay Results
- The Importance of Sampling in Metallurgical Assessment and Quality Control
- Assay quality – an overview
- Braden Copper Disaster – Implications for Modern Trackless Mining
Maintaining the quality Australia–wide.
Australian Laboratory Services’ experience and practice with satellite laboratories
QUALITY MANAGER, AUSTRALIAN LABORATORY SERVICES PTY. LTD. BRISBANE, AUSTRALIA
Quality does not happen by chance. It is generated by a combination of attitude, vigilance, common sense and adherence to correct operating procedures. A laboratory does not need NATA accreditation to provide the “correct results” but it must adhere to accepted good laboratory practice. The customer also has a role to play in the quest for quality by providing appropriate information.
Australian Laboratory Services (ALS) has developed its quality system based on ISO 9002 and ISO Guide 25 – “ General requirements for the competence of testing and calibration laboratories”. Each satellite laboratory must operate within the parameters of this quality system. This paper will discuss a number of the essential requirements with which each laboratory must comply and the procedures that ALS uses to monitor this compliance.
Assay Program Management – Planning For Quality
A.E. WALTHO AND W.J. SHAW,
Mining & Resource Technology Pty Ltd,
BRISBANE AND PERTH, AUSTRALIAem>
Maintaining the quality of assay data to be used in resource evaluation is a fundamental project management issue, readily addressed using a range of simple techniques to ensure the accuracy and precision of assay data. These effectively involve systematic submission of standards and resplit samples, and selection of samples for repeat assay by an independent laboratory. The most important aspects of these techniques are that:
- adequate planning for their use is required to ensure that resplit and appropriate samples for repeat assay are selected from each drill hole or batch of samples submitted for assay;
- appropriate standards are available; and,
- samples for resplitting or repeat assay are selected from appropriate grade ranges for the various elements of interest within the deposit.
All commercial laboratories employ trained, experienced personnel whose contribution to ensuring the quality of assay data should be maximised by consulting them during development of appropriate analytical procedures, based on as much information regarding the physical and mineralogical characteristics of mineralisation to be assayed as is available.
A range of methods for simple statistical analysis of results are available that enable the accuracy and precision of data to be quantified, and for these parameters to be compared between projects in a robust manner.
Ongoing attention to assay data quality enables more attention to be focussed on areas of greater uncertainty associated with the geological interpretation of, and grade estimation within deposits.[one_half]Request Copy[/one_half][one_half_last][back to top][/one_half_last]
Issues Concerning the Quality of Assay Results
PHILLIP L HELLMAN
Hellman & Schofield Pty Ltd, Suite 6, 3 Trelawney St, Eastwood Nsw 2122 Australia
“It is necessary that the assayer who is testing ore or metals should be prepared and instructed in all things necessary in assaying, and that he should close the doors of the room in which the assay furnace stands, lest anyone coming at an inopportune moment might disturb his thoughts when they are intent on the work.” Agricola
It should not be assumed that assays of samples collected during activities associated with mineral exploration, drilling and metallurgical testwork will be either accurate or precise. The onus of responsibility of monitoring quality should be on those who submit samples.
Assumptions of quality that depend upon, interalia:
- Certification or affiliation of the laboratory,
- Use of internal standards by the laboratory,
- Apparent accuracy of internal standards as reported by the laboratory,
- Agreement between original assays and repeat assays by a second, third or subsequent laboratory,
- Agreement between Calculated Heads and Head Assays in metallurgical testwork should not be made.
Numerous examples are presented highlighting problems such as:
- cross contamination of gold,
- incorrect assay technique leading to under-statement of gold,
- background analytical error resulting in delineation of waste as ore,
- assay bias induced by lithology and presence of coarse gold and
- incorrect calibrations.
These issues reinforce the need for the submission of control samples such as blanks and standards, as well as properly designed check assay campaigns, to:
- provide proof of accuracy and precision,
- provide early warning signals of assay problems,
- identify or eliminate the source of error when issues arise such as poor reconciliations (eg between resource model vs grade control, grade control vs mill),
- minimise risks associated with resource development.
The Sepon Project – Sampling and Assaying in an Exploration Project
Principal Geologist, Rio Tinto Exploration, Melbourne, Australia
Manager Exploration Support & New Resources , Rio Tinto Technology, Melbourne, Australia
The Sepon Gold and Copper project in Laos has been the focus of an intense exploration effort by Rio Tinto since 1993. From the time of project inception, the technical and management teams have implemented and maintained high standards of sample preparation, assaying and associated quality control. These aspects of the project will be discussed in detail.
The Use of Matrix-Matched Standards to Monitor the Quality of Assay Data
Manager Exploration Support & New Resources , Rio Tinto Technology, Melbourne, Australia
Exploration and new mineral resource developments generate large quantities of assay data, the integrity of which is critical to the viability of the project. One of the key requirements in minimizing uncertainty and improving the integrity of the geochemical data is to be able to measure and quantify the accuracy of the data. The best method to achieve this is through the use of check standards and preferably by using matrix-matched standards.
The benefits of using matrix-matched standards during exploration programs have been demonstrated on numerous occasions over the last ten years within Rio Tinto. The standards have proven to be a reliable and cost effective means of monitoring assay accuracy.
Laboratory Accreditation – A Confidence Framework for Laboratories and their Clients
ANTHONY J RUSSELL,
National Association of Testing Authorities, Sydney, Australia
The primary objective of laboratory accreditation is to provide public confidence in the competence of laboratories and in their ability to provide reliable data. The use of laboratory accreditation in the Australian mining industry has historically been patchy, despite the critical role of accurate data in the successful commercialisation of our mineral resources. A lack of understanding by laboratory clients of the process of laboratory accreditation, its limitations and its strengths, and how clients can capitalise on these, has contributed to a diminishing and poor representation of minerals testing facilities in the ranks of accredited laboratories in Australia. This paper explores these misunderstandings and reinforces the proposition that reliable, and useful, test data depends on a solid partnership between a competent laboratory and a well informed client.
An Audit Of Outokumpu Mining Australia’s Quality Control Practices
M.A. AHEIMER AND A.P. BLACK,
Outkumpu Mining Australia Pty Ltd. First Floor, 141 Burswood Rd, Burswood, WA 6100, Australia
Quality analyses are essential in nickel sulphide exploration and mining. The aim of these analyses is the accurate determination of the total nickel (in the form of sulphide minerals plus any non-sulphide nickel) and deleterious elements such as arsenic. The maintenance of a quality geochemical database requires a well documented series of control measures. Outokumpu Mining Australia Pty Ltd’s (Outokumpu’s) sampling and quality control procedures were audited to examine the effectiveness of these measures and to resolve the inconsistent reporting of analyses encountered with laboratory data.
Initially the relevant standard, field duplicate and pulp residue re-assay data was extracted from each project. These data were analysed statistically using a series of scatter plots and Shewart Control Charts to determine the precision and accuracy of the data sets. The procedures used to insert standards, field duplicates were also critically reviewed. The effects of these procedures were taken account of in the review of current and previous analytical data. Mineralogical influences on the total extractable nickel and the necessary checks needed to account for such mineralogical influences have been considered and incorporated in the review of analytical data.
The Audit has shown that Outokumpu’s performance has been varied. Sampling procedures and sampling and analytical quality control have been well executed and the choice of materials for standards has been good. Outokumpu has been less effective in the recording, analysis and use of the quality control data. This aspect of Outokumpu’s quality control could have been better executed, otherwise it is a waste of time and money. The laboratories have overall performed poorly, there are a numerous sample batches with unacceptable results, and a number of sample batches with large errors. The underestimation of the detection limit for AAS arsenic has resulted in low precision arsenic assays for Honeymoon Well and Forrestania. It is recommended that the Black Swan Nickel Mine should insert its own standards on site, so they are sending a “blind” standard for which the laboratory doesn’t know the accepted values.
Deep Sea Tailing Placement
STUART JONES AND DR DAVID GWYTHER
NSR Environmental Consultants Pty Ltd
124 Camberwell Road, Hawthorn East, Victoria 3123, Australia. Web: http://www.nsrenv.com.au
Successful management of tailing presents technical challenges for mining operators and their regulators in all parts of the world where mining occurs. Constraints and uncertainties exist for all tailing management options. Understandably, communities located near existing or proposed mines perceive the uncertainties as ‘risks’ to either their shared use of the environment, their livelihood and/or their personal safety.
Two types of tailing management are considered in this discussion paper: on-land tailing storage in man-made structures: and deep sea tailing placement1 (DSTP), defined as the planned deposition of tailing solids in a specific area located deep below the ocean surface.
This paper introduces the fundamental differences between on-land tailing storage and DSTP. It describes both low- and high-risk environments for on-land tailing storage and then introduces DSTP as a proven technology and describes the natural characteristics of seawater that are favourable for the development of this technology.
It then identifies mines that have used, are using, or are proposing to use DSTP and briefly mentions two examples of past and present DSTP implementation. The legality of DSTP under International Law and under US and Canadian Law is then discussed. The paper concludes with an outline of where DSTP could be utilised.
Unrealistic Expectations of Assay Results
JOHN EAMES BSC (HONS), FRACI, CHARTERED CHEMIST, MAUSTIMM,
Laboratory Quality Management Services Pty Ltd, Sydney, Australia
The integrity of a resource database is pivotal to a company’s success in securing debt or equity finance for a new mining project. The quality of data and thus the validity of the database can only be guaranteed when appropriate sampling and assaying protocols have been implemented. No amount of mathematical sophistry can replace them.
This paper examines the key sampling, analytical and quality assurance factors impacting on project success and how a project manager should set about establishing an analytical protocol in liaison with a commercial laboratory. What can really be expected from assay data? Laboratories are not perfect, mistakes can happen we are all human, even geologists make mistakes. It is the duty of both the chemist and geologist to minimise mistakes, and ensure that assay data is fit for purpose. An analytical performance specification should be clearly defined in contract documents ensuring laboratories deliver technically sound and legally defensible assay results. It is irresponsible to assay samples using a “cheap and nasty” geochemical technique if the project involves resource estimation.
The Importance of Sampling in Metallurgical Assessment and Quality Control
Presented at SHINE – The Australasian Metals Symposium, Surfers Paradise, 16-19 August 1998
RALPH J HOLMES,
CSIRO MINERALS, PO BOX 883, KENMORE QLD 4069
With the increasing pressure from customers for better quality control, it is surprising that sampling is often ranked as an area of relatively low importance. The task is delegated to personnel who do not fully appreciate the significance and importance of sampling, and major flaws in sampling procedures and equipment do not receive the attention they deserve. Yet correct sampling and sample processing practices are critical to delineation of ore resources and control of subsequent processing operations from mining through to delivery of the final product. In simple terms, there is little point in making major capital investment in the latest analytical equipment and spending considerable time obtaining the best analytical precision, if the sample presented for analysis is not representative in the first place. In essence, the entire measurement chain has been corrupted at the outset.
Failure to meet product specification can have serious consequences, such as penalties and loss of sales contracts. Poor knowledge of ore quality and large measurement uncertainties also limit the ability of operators to optimise the life of ore resources, because target grades are often set high to avoid penalties. Unsatisfactory sampling practices will also result in poor metallurgical balances…
Assay quality – an overview
Becquerel Laboratories, Lucas Heights, NSW, Australia
In recent years geochemistry has been responsible for more discoveries of mineral deposits in Australia than any other exploration technique. The samples collected in order to make these finds were analysed in commercial laboratories and in the great majority of cases it would be reasonable to argue that the results were acceptable – they enabled the user to make technically correct decisions and they were therefore fit for the purpose of locating the positions of potentially economic mineral deposits. Furthermore, the development of many new mines attests to the fact that analyses were of a sufficient standard to allow evaluation of mineral resources and ore reserves once those deposits had been located. Minerals laboratories have played their part inthese successes and deserve credit for this.
Nevertheless, analytical mistakes have been made and will continue to be made so long as human beings are involved in the analytical process. It would be unrealistic to expect perfection in an industry that produces millions of analyses per annum. The challenge is to keep these mistakes to a minimum; to detect them as fast as possible when they do occur; to react appropriately once they have been identified; and to learn from them in the hope that they can be avoided in the future. A further challenge centres on the need for accurate results with well defined limits of uncertainty.
Braden Copper Disaster – Implications for Modern Trackless Mining
F. AusIMM B.E Mining (Hons)
The Braden Copper disaster occurred at the El Teniente mine now owned by Codelco and resulted in the deaths of 355 men. The fire started in a workshop adjacent to the mine air intake and initially involved a relatively small amount of oil. This paper presents a brief description of the events of that day and draws parallels that might apply to diesel equipment fires in modern trackless mines and implications for ventilation system design. The descriptions of the fire have been drawn from reports provided to the Author by the U.S. Department of the Interior M.S.H.A. Library and include a Bureau of Mines report on the incident as well as a report from the Proceedings of the 4th US Mine Ventilation Symposium, March 1989. While these two reports are considered definitive there are some minor differences.