13-qaqc and sample security
TRANSCRIPT
-
8/12/2019 13-QAQC and Sample Security
1/26
Considerations on QA&QC and Sample Security
Armando Simn and Greg Gosson
AMEC Americas Limited
Sampling 2008, 27-29 May 2008, Perth, Western Australia
-
8/12/2019 13-QAQC and Sample Security
2/26
Presentation Outline
QA/QC and Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 2
Objective assessment of precision
Why blind insertion of control samples?
QC versus Sample Security
Recommendations
-
8/12/2019 13-QAQC and Sample Security
3/26
Introduccin
"Bre-X Minerals eolo ist
The BreThe Bre--X AffairX Affair
Sampling 2008, 27-29 May 2008, Perth, WA 3
Michael de Guzman, centre,conducts a survey with hiscolleagues at the Busang-2 fieldin Indonesia in this March 1997
picture. (Associated Press/Gatra
Magazine)
-
8/12/2019 13-QAQC and Sample Security
4/26
Introduccin
Sampling 2008, 27-29 May 2008, Perth, WA 4
!
" #
-
8/12/2019 13-QAQC and Sample Security
5/26
Quality in NI 43-101
All written information of scientific or technical naturerelated to mining projects should:
Introduccin
Sampling 2008, 27-29 May 2008, Perth, WA 5
Specifyif a Qualified Person verified the data on which
this information is based, including sampling, assayingand tests
Describethe quality assurance program and the qualitycontrol measures
Describethe nature and limitations of such verification
Explainany deficiencies detected during the verification
-
8/12/2019 13-QAQC and Sample Security
6/26
Quality in JORC
A Competent Person report should:
Introduccin
Sampling 2008, 27-29 May 2008, Perth, WA 6
Describethe nature, quality and appropriateselection of sampling and analytical procedures
Describethe quality control procedures, includingthe insertion of standards, blanks, duplicates and
external checks
Assessthe accuracy and precision levels attained
during the project
-
8/12/2019 13-QAQC and Sample Security
7/26
However, quality of geological data is a matter
of concern not only for companies working under
Introduccin
Sampling 2008, 27-29 May 2008, Perth, WA 7
- , or o er w e y recogn ze co es:
Hundreds (or thousands?) of private exploration
companies, mines and laboratories are involved
in exploration and mining all over the world.
-
8/12/2019 13-QAQC and Sample Security
8/26
Consequence of Lack of QC Protocols
(or Poor QC Protocols)
Entire drilling campaign data may have to be partially or
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 8
totally excluded from the resource estimation databases
The estimated resources may be down-graded
If QC data were not timely processed, then only aforensic analysis can be done.
-
8/12/2019 13-QAQC and Sample Security
9/26
Quality Control
Hence, we need comprehensive
geological QC programs!!!
Sampling 2008, 27-29 May 2008, Perth, WA 9
,
appropriate measurements (if necessary)
Assessing precision (sampling, sub-sampling,analytical)
Assessing accuracy
Assessing contamination during preparationand assaying
-
8/12/2019 13-QAQC and Sample Security
10/26
Assessment of Precision (1)
ISO 3534-1 defines precision as "the closeness of agreement
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 10
conditions.
Repeatabilityconditions are fulfilled when re-sampling occurs inthesamesampling intervals, with thesamesampling procedure,
when samples are processed with thesameequipment and thesame preparation procedure, and are assayed with the samemeasuring instrument, under thesamemeasurement conditions,and are repeated over ashort period of time.
-
8/12/2019 13-QAQC and Sample Security
11/26
Assessment of Precision (2)
Therefore, an objective assessment of precision on repeatabilityconditions requires thatthe original and the duplicate samples be
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 11
.
However, at least for preparation and pulp duplicates this isseldom accomplished:
Duplicates are usually inserted in another batch, sometimesmonths (or years) later, or
Duplicates are submitted to another laboratory, alleguedly toassess precision.
-
8/12/2019 13-QAQC and Sample Security
12/26
Is Independent QC Actually Needed? (1)
Internationally certified and competently managed laboratorieshave their own internal QC rotocols and the assa certificates
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 12
commonly include the results of at least some of the internallaboratory QC. However,most laboratories will only reveal thosechecks that pass their internal controls, but not the failures.
Problems with sampling, preparation and assaying areseldomtheresult of dishonest attempts to hide or falsify certain facts, butratherunintentional errors or biasintroduced by improper samplecollection, preparation and assaying.
-
8/12/2019 13-QAQC and Sample Security
13/26
Is Independent QC Actually Needed? (2)
However, from time to time we witness some deceptive practicesat the laboratory, like:
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 13
Altering the sample order:
Preparing all the ordinary samples first, and leaving theblanks to be processed at the end, after cleaning theequipment
Correcting the values of the whole batch to compensate for thedeviations from the CRM certified value.
-
8/12/2019 13-QAQC and Sample Security
14/26
Is Independent QC Actually Needed? (3)
Quality Control
Sampling 2008, 27-29 May 2008, Perth, WA 14
n or una e y, regar ess o e goo n en ons o a ora orymanagement, the incidence of poor sample preparation practicesand unreported blank, duplicate and CRM failures ishigher thanexpected or desired.
Sole reliance on the internal laboratory QC is anunacceptably poor practice.
-
8/12/2019 13-QAQC and Sample Security
15/26
Do We Need Blind Insertions? The identity and characteristics of the control samples must remain
unknown to the controlled entity. Otherwise, the objectivity is lost,
Blind Insertions
Sampling 2008, 27-29 May 2008, Perth, WA 15
e con ro may no onger e va , an can consequen y e ca einto question.
The purpose of the blind insertion of control samples is to preventthe laboratory from identifying the control samples, or at the very
least, their nature and sought values, so that an objective andindependent assessment of precision, accuracy and contaminationcan be conducted.
-
8/12/2019 13-QAQC and Sample Security
16/26
Are Blind Insertions Possible?
Blind insertion of field duplicates and coarse blanks can be easilyconducted at site, during the sampling process.
Blind Insertions
Sampling 2008, 27-29 May 2008, Perth, WA 16
Blind insertion of other control samples (same-batch preparationand pulp duplicates, CRMs, pulp blanks) would require insertion intothe batches during or after sample preparation, and prior toassaying.
Unless sample preparation and assaying take place at differentlaboratories or facilities,this operation would be impossible withoutthe participation of non-laboratory personnel.
-
8/12/2019 13-QAQC and Sample Security
17/26
Then, What About Sample Security?
Under these conditions, samples would have to be temporarilyreturned to the custody of anon-laboratory personin charge of theinsertions, even if this occurswithinthe laboratory premises.
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 17
Is this an acceptable practice? Does it represent a breach in theChain of Custody principle? If so,what do we give up?
Proper assessment of precision, accuracy and contamination? Sample security and the Chain of Custody principle?
Are those two alternatives compatible?
-
8/12/2019 13-QAQC and Sample Security
18/26
Being in Custody
A sample is considered to be in custody if it meets at least one of
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 18
t e o ow ng con t ons:
The sample is insomeones physical possession or view;
The sample issecured to prevent tampering; or
The sample is secured in an area restricted to authorizedpersonnel.
(WSDE, 2007)
-
8/12/2019 13-QAQC and Sample Security
19/26
Chain of Custody
Chain of Custody is defined as "an unbroken trail of accountability
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 19
a ensures e p ys ca secur y o samp es, a a, an recor s
(EPA, 1998).This definition has to do withsecure traceability.
According to this definition, respecting the chain of custody impliesthat it should be known and documented who has custody of asampleat any particular moment. As long as this principle is followed,
the chain of custody concept is respected.
-
8/12/2019 13-QAQC and Sample Security
20/26
Currently accepted situations when neither the company
nor the laboratory are in permanent custody of the samples:
Samples are taken on site, andsubmitted for preparation and assaying to
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 20
, ,
buffalo, truck, bus, train, plane, mail or courier), using company personnel orcontractors (individuals, same laboratory, another laboratory or othercontractors).
Samples are prepared on site by company personnel or by a specialcontractor or by laboratory personnel, and are submitted for assaying toanother location(city, country or continent) by various means (horse, waterbuffalo, truck, bus, train, plane, mail or courier), using contractors (individuals,
same laboratory, another laboratory or other contractors).
-
8/12/2019 13-QAQC and Sample Security
21/26
Currently accepted situations when neither the company
nor the laboratory are in permanent custody of the samples:
Samples are prepared by a laboratory facility in one location andsubmitted
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 21
or assay ng o ano er ac yo e same a ora ory n e same oca on or
in another location (city, country or continent) by various means (truck, bus,train, plane, mail or courier) using laboratory personnel or various contractors
(individuals, laboratory, other contractors).
Samples are prepared by a laboratory facility in one location andsubmittedfor assaying to another facilityof another laboratory in the same location or inanother location (city, country or continent) by various means (truck, bus,
train, plane, mail or courier) using laboratory personnel or various contractors.
-
8/12/2019 13-QAQC and Sample Security
22/26
Therefore, in spite of the fact that potential
Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 22
amper ng poss es ex s , suc s ua ons
(and others) are customarily accepted because
changes of custody are well documented with
Chain of Custody forms.
-
8/12/2019 13-QAQC and Sample Security
23/26
Conditions for Blind Insertions
The QP is entitled to follow or to accept practices based on
Quality Control versus Sample Security
Sampling 2008, 27-29 May 2008, Perth, WA 23
criteria that aregenerally accepted by the industry, or thatcan reasonably bejustified on scientific or technical grounds.
The QC process should be sufficientlytransparentto preventany suspicion of improper behaviour or actions; an essentialrequirement is that the events should be adequately
documented.
-
8/12/2019 13-QAQC and Sample Security
24/26
When AMEC is retained by an exploration or mining companyfor the independent, ongoing review of a quality controlprogram:
Atrained AMEC employeeis in charge of the blind insertion
of control sam les at the laborator remises with
AMECs Blind Insertion Practice
Sampling 2008, 27-29 May 2008, Perth, WA 24
authorization of company and laboratory management; Control samples are repackaged in pouches identical to
those used for unknown samples, supplied by the laboratoryon the spot, and chain of custody forms are filled by theAMEC and the laboratory representativesat the time when
sample custody changes. AMEC does not recommend nor accept that samples be
retrieved from the laboratory premisesbefore assaying for the
insertion of blind control samples or for any other purpose.
-
8/12/2019 13-QAQC and Sample Security
25/26
Using one laboratory (or branch) for preparation and insertion of thecontrol samples, and another laboratory (or branch) for assaying.This procedure can be considered as best practice.
Using trained personnel independent of the exploration or mining
Recommended Blind Insertion Procedures
Sampling 2008, 27-29 May 2008, Perth, WA 25
company, w t no veste nterest n t e pro ect, to o t e ninsertionswithin the laboratory premises. This process should bewell documented with chain of custody forms. This procedure can beconsidered as best practice.
Using a trained person from the company to do the blind insertionswithin the laboratory premises. The process should be welldocumented with chain of custody forms. This procedure can beconsidered as acceptable.
-
8/12/2019 13-QAQC and Sample Security
26/26
Final Recommendations
Implement from Day 1 a comprehensiveQA/QC
Sampling 2008, 27-29 May 2008, Perth, WA 26
.
Use same-batchduplicates.
Use blindinsertions.
Keep proper records of changes of custody.