qaqc.pdf

QAQC : Théorie

Accurance= proximité de la valeur par rapport à la vrai valeur.

Précision=proximité de la valeur par rapport aux autres valeurs.

Formule de Gys=FE=erreur fondamentale

Fi2=variance (de l’erreur fondamentale)

Fi2 (FE)=(1/MS-1/ML)xfxgxcxlxd3

MS=masse sample ML=masse lot

F=forme=0.5

G=taille de distribution=0.25

c=composition minéralogique

l=libération l=0 si très hétérogène et l=1 si très homogène (entre 0 et 1)

D=plus grosse particule 95%=taille broyage

Fxgxcxl=constante échantillon=C

Plus ML est grand, plus il devient négligable !

Donc : Fi2 (FE)=(1/MS-1/ML)xfxgxcxlxd3=Cd3/MS soit Fi2 diminue si MS augmente et d

diminue. Donc il faut un grand échantillon et un broyage très fin.

Calcul de C :

C=fxgxc=0.5*0.25*l*c

C=(1-a)*((1-a)dens a+ a dens g)/a ou a=teneur de la calcopyrite dans minerai (g=gangue).

Si 34.5% de Cu dans calco, 0.8% cu dans minerai=quartz alors a=0.008/0.345=0.0232=2.32%

Si a très petit c=dens a/a

3 applications à la formule de Guy : Fi2 (FE)=(1/MS-1/ML)*C*d3

-estimer variance Fi2

-estimer Ms=poid minimum de l’échantillon

-estimer d=taille maxi des particules

Ex : calcul de Fi avec 0.8% de Cu broyé à 12.5mm avec un éch de 50kg ?

Fi2=Cd3/Ms (Ms=50000g/ d=1.25cm/dl=0.01cm/l=0.9)

C=1.95 g/cm3

Fi2=76*10-6 et racine de Fi2=Fi=0.87% ou 2Fi*0.8%Cu=+/- 0.014 %Cu

Exemple : On part de 2m de carotte=25kgjaw crusher 5mm puis roll crusher 1mm24kg

reject et 1kg que on pulvérise à 100microns700g de pulps stochage et 300g pour analyse

type FA

Utilisation du nomogram pour être sûr qu’on est en dessous de la safety line (10% de Fi2).

Pour l’or, on utilise le fcateur de bongarcon car Guy est trop conservatif :

Fi2= c*f*g*dl^1,5*d^1,5/M

Avec :

-dl=25 micron

f=0,5

-g=0,25

-c= si grade=5g/t-->5,10^-6 et c=19,3/5,10^-6

La première étape de broyage fct de Msample, va jouer énormément sur Fi2 !!! il faut broyer

finement un gros échantillon dès le début.

Ex : à 2cm et 2 kg ça donne une erreur de 30% ce qui est énorme !!!

FORAGE

RC : 3 types

* rotary= injecte par le tube et ressort entre tube et encaissant=possible contamination

*reverse=injection entre tube et roche, aspiration par le tube

*reverse dual=comme RC mais avec un 2ème tube qui colle à la paroi ! pas de contamination possible.

-Recovery mesuré grace au poid à l’inverse du core gace à la longueur.

-Besoin de spliter à l’aide d’un RSD ( rotary sampling dividers, à chnager si trop vieux) ou riffle

splitter.

-Un cyclone permet de récupérer les échantillons.

-Un tube de 5 pouces produit 36 kg/mètre de forage !!!

-les éch : des gros morceaux de plus de 4kg mieux que plusieurs petits morceaux.

Possible : cone et splitting, pelle, pattern sampling, RSD, riffles. Tj s’assurer que le lot est

homogène !!!

ECHANTILLONNAGE

Facteur qui affecte l’échantillonnage :

-mauvaise récupération

-mauvais quartage

-perte d’échantillon

-contamination (attention poussière autour du rig, condition de stockage, manipulation des ouvriers,

pas nettoyer entre 2 samples, abrasion des équipements qu ipartent avec les samples comme le fer,

le cuivre, l’aluminium ou la céramique....)

3 étapes :

-séchage (24h à 100C)

-broyage=crushing (jaw crusher) puis concassage=grinding et pulvérisation=pulverising (mixer mill))

-blending=homogénisation et splitting

Lors de la réduction de taille, tj s’assurer que plus de 95% des particules soit passées sur la

maille indiquée.

Attention à bien nettoyer le splitter et les mills entre chaque sample !!!!

Surveiller le temps de broyage !!!

On appelle rejet le reste de l’échantillon soumis après retrait de l’échantillon splitter à analyser. Ils

servent de duplicate. Il est important de prendre des duplicates à plusieurs étapes de broyage

DUP1,2,3 pour contrôler l’efficacité des broyeurs et du quartage.

La pulpe, plus généralement issue du mills ?

RIFFLE :

*attention aux biais produit si :

-matériel est humide

-introduit pas au milieu et dans le bon sens

-la taille de la particule est sup à 3x l’espacement des dents

- plusieurs manips et en cascade

Analyses OR :

-Aqua regia/AAS= l’or est dissous dans une mixture nitrique et hydrochlorique puis analyser par AAS.

Peut sous-estimer l’or si silicate et sulfure ne sont pas bien dissous ou brulés !!!

-Fire Assay= fusion de l’or et l’Ag sur une coupelle en plomb. Le plomb est volatilisé et l’or analysé

par AAS. C’est le plus utilisé pour l’or. Besoin de 25g pour l’analyse finale ! FA que pour Or ou Ag.

Analyse métaux :

-ICP=dissolution multi acide puis excitation atomes par traitement HT. Les photons émis sont analysé

par spectromètre en analysant la longueur d’onde spécifique de chaque atome ! Il permet une large

suite d’éléments !

-AAS=pareil mais les atomes sont excité par des par des rayons de longueur d’onde différentes en

suite. Adsorption atomique spectromètre. Il permet une large suite d’éléments !

-XRF=émission de RX spécifique de chaque atome après soumission de l’échantillon à un flux

d’électron. Non destructif et pas besoin de calibration à l’inverse des 2 autres. Idéal pour le fer,

bauxite et l’uranium.

QA/QC :

-std=mesure l’accurance et la qualité des analyses (labo)

-duplicate= mesure la qualité de l’échantillonnage et la précision

-on utilise 3-5 std par projet

-rapport cout/efficacité, 1/20 std c’est ok

STD

-on fait un plot avec +/- 2SD, fournis avec le sample. Les valeurs doivent être entre la ligne moyenne

et les 2SD.

-si non : attention à la dérive temporelle (downward pattern, problème de calibration, labo drift),

l’effet pépite (clusters effect), il faut réanalyser les rejects et contacter le labo, problème de

contamination ou de standart pas du labo…

RSD= relative standart deviation=SD/valeur moyenne concentration*100 (%)=mesure de la

précision !

DUPLICATE

-MAPD= mean absolute pecent différence in %=2*ABS(x1-y1/x1+y1)x100 ça marche par paire !

Entre 2ech.=mesure de la précision

-Scatter plot

-q-q plot

Cross plot

1

1,5

2

2,5

3

Au ppm

Count

OxJ64

OxJ64

Certified value

+3FE

-3FE

0

10

20

30

40

50

0 10 20 30 40 50

Au (

g/t)

Au (g/t)

Au-Au Lab Replicates (0-50)

Au-Au y=x y=0.9x y=1.1x

RANKED HARD

Pair MEAN

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0% 20% 40% 60% 80% 100%

HA

RD

Rank

Intertek Pulp duplicates Ranked Hard

RankedHard

1%

5% 10% 20% 50% 100%

0,000

0,001

0,010

0,100

1,000

10,000

100,000

0,10 1,00 10,00

HA

D (

Half A

bs.

Diff.

- p

pm

)

Pair Mean - Au ppm

Intertek Pulp duplicates Pair Mean / HAD

0

20

40

60

80

100

120

140

0 50 100 150

All

Data

Original

Q-Q : Original / All Data

Avec ces graph, on voit si il y a un biais

-1/20 sample c’est ok !

BLANKS

-mesure l’accurancy !

-1/40 ok.

DBD=dry bulk density=Mdry/Vbulk

Vbulk=si core régulier=diamètre par longueur.

Vbulk=si core pas régulier=M eau qui sature sample- M eau qui immerge sample (voir descriptif) dans

ce cas il y a 3 mesure à faire de poids !!!

La représentativité d’un échantillon peut être affecté par :

-mauvaise recovery

-roche friable, argileuse ou en bloc

-type de minéralisation aléatoire : veine, effet pépite, cisaillement, faille

-technique de forage

-mauvaise pratique, procédure et équipement

TEST d’HETEROGENEITE=Monogram

Il faut que Fi2 soit tj inférieur à 10%

Lot Split 1

Crush 1

Split2

Crush 2 Split 3 Crush 3

Split 4

0,0000001

0,000001

0,00001

0,0001

0,001

0,01

0,1

1

10

100

1000

1 10 100 1000 10000 100000

s2

FS

E

Mass (g)

Sampling Nomograph

1 cm0,2 cm0,0125 cm0,0075 cmProcess5%

Labo : en choisir au moins 2, voir 3 ! utiliser différente technique comme AAS, FA, Aqua regia.

Si on utilise 0.1g d’acide ou 0.5g (plus cher), on va sous-évalué les teneurs !

Ne pas oublier que sur 100 Mt de ressource, seul 1-5 kg seront analysé !!!!

L’hétérogénéité est vérifiée avec les duplicate !

Si les grains sont trop gros, mieux vaut utiliser le FA gravi que AAS !

L’or grossier est très compliqué à estimer.

Pour un d= 1cm (crusher ?), il faudra un sample de d lib=200 micron, alors que pour un

dlib=10 micron, il faudra 650 g !

-il faut mieux grinder à 1mm ou 0.5mm dès le premier broyage ! en effet avec d=1mm, il faut

1.7 kg de sample à dlib=200 micron.

-l’or est très dense et se segregate très facilement notamment avec l’eau en RC, durant le

split, ech secoué au labo ou pendant la préparation…Cela peut introduire des biais !!!

-l’or est mou et ductile et peut contaminer d’autres sample pendant le broyage si il reste

collé. Très difficile à broyé de façon homogène !

-ne pas hésiter sur l’hétérogénéité avec duplicate et le temps de broyage.

-l’or est visible à 150 micron ! Il est grossier si sup à 75 microns, sinon il est fin. Mais les 2

apparaissent dans un même éch !

QAQC : PRATIQUE

Drillhole deviation measurements

Drillhole deviation should be measured at 10m depth and then every 30m downhole.

Take deviation readings as the hole is drilled for all diamond drill holes and monitor for any

strong deviation. Hole deviation should be plotted to ensure that the hole will reach its

designed target. If the hole deviates to much it may need to be stopped and re-drilled.

Core recovery

Core recovery could possibly be a problem for the diamond drilling. Monitor this closely

especially in the ore zone.

If poor core recovery occurs make the driller aware of the situation. He can try and improve

recovery by drilling shorter runs. Also notify the project geologist as changes to drilling

techniques may be needed.

Core orientation

For the drill core we want to orientate the core so that structural measurements can be

made. This program will be a good opportunity to gain experience with core orientation

geotechnical and structural logging

Make sure that the drillers drop the spear tool down the hole to mark the bottom of the core

every 6m and that they mark the orientation line on the end of the core. The completion of a

spear orientation should be noted on the drillers log book.

The core may often be very broken or very oxidised. If this is the case it is not suitable for

taking orientation readings. The driller can generally determine this. Check to make sure

that the driller does take measurements if the core is competent.

Drill core is then orientated once the core has been taken to the core logging shed.

Sampling

Diamond core:

The sampling procedure generally follows SOP: CORE5

At the core facility:

The drill core will be orientated if possible. Metre intervals to be marked on the core and drillers measurements checked.

Diamond core will be technically, geologically and structurally logged by the geologist.

Core will be checked after sampling and additional detailed geological logging carried out if the cut core surface improves geological observations.

The intervals for analysis will be clearly marked by the logging geologist. Sample length should generally be between 0.5-1.5m, dictated by geology with most sampling by 1m intervals. If significant core loss (>20cm) has occurred the sample intervals should be between core blocks (i.e. samples should not cross core blocks).

A list of the sample intervals should be provided to the core samplers so that core can be cut and sampled. And a copy of the list to the Project/Senior Geologist to prepare the QA/QC sampling list.

The QA/QC to be used is specified by the Project/Senior Geologist based on the following guidelines. QA/QC procedure based on selective sampling of the mineralised zone; per 100 samples: 4 standards, 2 blanks and 5 duplicates. (Duplicates should be selected from the interpreted mineralised zone and be inserted after the primary number in the sampling sequence). Refer to Quality Assurance SOP Chapter 5.

The left half of the core is to be retained in the core tray and the right half sampled.

Each sampled interval is to be placed in a sample bag. Sample bags will be numbered using the usual convention: example – hole id HAW_D001, 78-78.8m would be labelled HAN_R001-78.8

On completion of sampling samples are transferred to the sample preparation facility.

At the sample preparation facility:

The entire sample is primary and secondary crushed. Twice through the jaw crusher and twice through the cone crusher.

The sample is then split to give a 500g sub sample. The residue is retained in labelled sample bags in the container.

The entire 500g sub-sample is then pulverised in the ringmill.

The pulverised 500g sample is split to produce a 125-250g sample to be packaged in a geochem envelope for sending to the laboratory for analysis. The remaining 250-350g of sample is retained as a witness sample.

Samples are packaged and sent for analysis at Intertek for Au by method FA50. Samples which show signs of base metal mineralisation (eg. Sulphides of oxidised Cu minerals should also be analysed for base metals)

RC drilling:

Usual procedures for RC sampling will be employed (same as Kamoeb drilling in 2009). The

sampling procedure generally follows SOP: RC3.

At drill rig:

The samples from the cyclone will be weighed and split generating a ~5kg sample, with the splitter residue generally discarded (see below).

When the ore zone is intersected (indicated by gossan or oxidised altered material) the geologist should instruct the sampling workers to retain the splitter residue in labelled plastic bags. These can be placed next to the drill site in rows for future use. The reason for this is that larger amounts of the ore zone will be required for future test work.

Sample bags will be numbered using the usual convention: example – hole id HAN_R001, 0-1m would be labelled HAN_R001-001

Samples are transported to sample preparation facility at the exploration hanger.

Drill chips should be placed into chip boxes for each metre. With the boxes labelled with the depth intervals and hole id.

At sample preparation facility:

The QA/QC to be used is specified by the geologist/exploration manager based on the following guidelines. QA/QC procedure per 100 samples: 4 standards, 2 blanks and 5 duplicates. Refer to Quality Assurance SOP Chapter 5. Duplicates should be selected from interpreted mineralised intervals and should follow in ticket number the primary sample.

A sampling list detailing sample ticket numbers and QA/QC is provided by the Project/Senior Geologist to the Laboratory Manager.

Samples are dried if required.

The sample is split to give a 1kg sample and a bulk residue. The bulk residue is stored in container for later check analysis if required.

The sample is put in a small plastic bag.

A sample number is allocated to each sample interval from the ticket book as described in the sampling list.

Samples are pulverised in the ring mill.

The pulverised 1kg sample is then split to produce a 125-250g sample which is placed in a geochem envelope for shipment for assay. The remaining 750g sample is kept as a reference sample.

Samples are packaged and sent to Intertek for analysis for Au by method FA50.

Responsibilities of the Rig geologist

Make sure that the drillhole is drilled at the correct azimuth and dip

Supervise the sampling and ensure that good practices occur, no contamination, samples correctly labelled, weighed, etc.

Collect and check deviation information as the hole is drilled, pass this on to the Project/Senior Geologist to be checked.

Logging geology (RC & Dia) and structure, geotech (Dia).

Provide details of drilling, mineralised zones, geology to the Senior/Project geologist.

Draw field sections to show drillhole as it is drilled

Ensure that data is correctly entered into the daily drill reports on the computer.

Review drill results and check that data is correct in the database.

1. AMC Duplicate Sampling

The main aim of duplicate samples will be to test the reproducibility of our sampling and

assaying procedures. This will determine if the results we receive for samples are

repeatable and accurately representing the mineralisation of each sample interval.

Matrix effects or contamination during the sample collection and preparation process should

be identified.

In contrast the aim of the Standards and Blanks dispatched to the assay lab is to test the

precision and accuracy of the lab.

Check samples or duplicates of the lab pulps can be submitted to an umpire laboratory to

also test the quality of the primary laboratories precision and accuracy.

1.1 AMC Duplicate Procedure

Routine Duplicate sampling for AMC will involve a duplicate taken at the second division of a

sample, (DUP2 see below). Everything in the sampling process should remain constant,

same sample preparation procedure, same laboratory, etc.

Duplicate samples will be selected by the Project/Senior Geologist according to samples

most likely to contain mineralisation as interpreted from the drillhole logs. The duplicates are

then inserted into the sampling sequence directly after the primary sample (this is to simplify

the process for the sample preparation workers). The duplicate samples should be clearly

identified on the sampling sheets provided to the Preparation Laboratory Manager.

As the 500-1000g sub-samples for pulverising are split from the samples at the hanger a

duplicate sample is also prepared in the same manor and inserted into the ticket numbering

sequence after the primary sample as defined by the sampling sheet. This sample will then

be treated in the same way as a normal sample during the sampling preparation procedure

and assay.

Rate for duplicates should be 5 samples per 100 when the entire hole is sampled and 9

duplicates per 100 samples when mineralised intervals only are sampled.

1.2 AMC Check Sample Procedure

Check samples should be carried out at a rate of half that for routine duplicates. Samples

should be selected once pulps have been returned from the primary laboratory and prepared

with QA/QC samples inserted and sent to a selected umpire laboratory for analysis.

Sampling lists should be prepared by the project/senior geologist to select a range or

anomalous assay values. Samples should then be prepared under the supervision of the

Preparation Laboratory Manager according to this list. Check samples should get new ticket

numbers and have QA/QC samples included in the sampling sequence.

1.4 Database Management

The duplicate samples can be managed as outlined in the document ‘Quality

Assurance/Quality Control Hassai Camp – Geology Manual: Sampling and sample

management quality control data flow resources/reserves’ version 1.2, October 2009.

The following (in italics) is taken from this document and modified slightly as indicated (blue

text).

Duplicate samples will be given the Hole ID, depth from and depth of the sample being

duplicated. The Sample ID of the duplicate sample will be the same as the sample being

duplicated followed by a D to indicate that it is a duplicate sample (eg; KAMS_R001-006D).

If more then one duplicate of a sample is analysed a number is added after the D to indicate

this (eg KAMS_R001-063D1). An example of the Sample ledger for Duplicates is shown

below.

Hole_ID Depth_from Depth_To QA/QC Type Sample_ID

KAMS_R001 5 6 DUP2 KAM_R001-006D

KAMS_R001 31 32 DUP2 KAM_R001-032D

KAMS_R001 62 63 CHECK KAM_R001-063D

KAMS_R001 62 63 DUP2_1 KAM_R001-063D1

KAMS_R002 10 11 DUP2 KAM_R002-011D

The following identifier system is proposed for identifying duplicate samples taken at different

stages of the sampling procedure. This can appear in the “QA/QC Type” column as shown

above.

DUP1 First division of a sample

-For diamond core sampling this would be a duplicate ¼ or ½ core

sample.

-For RC sampling the duplicate would be taken as a second split of the

original RC sample at the rig site.

DUP2 Second division of a sample

-For diamond core this would be a duplicate of the 500-1000g sub-

sample for pulverising split from the crushed original core sample.

-For RC samples this would be a duplicate of the pulverised 1kg

sample split from the sub-sample collected at the rig site.

DUP3 Third division of a sample

-This would be a duplicate of the 125-250g sample sent for analysis at

the lab which was split from the pulverised sample.

CHECK Lab Check sample

-This is an assay by an umpire laboratory of the remaining pulp sample

returned from the primary laboratory.

Date: 10/10/2009 Version1.2 Prepared by: R. Bosc, M.Bennett, M. Barbut

Approved by: Exploration

Manager

Executive Deputy

Manager

Chief Geologist Field Manager

ARIAB MINING

COMPANY Ltd

Sample preparation

Standard Operation

Procedures

To

p: 8

8.3

m

Bo

tto

m: 9

2.7

m

88.8

91.1

Rig site

Geologist Supervision

Left half

core kept as

a reference

in the core-

box4- 5 kgSample

Number

To

p: 8

8.3

m

Bo

tto

m: 9

2.7

m

DH

: D

D_U

MA

SH

AR

_0

02

PQ

–B

ox

13

Fro

m 8

8.3

m to

92

.7m

88.8

91.1

Properly identify and label:

-Top and bottom

-Core Blocks

-All depths

Hole-ID, Depth from and

to, Box no, on the core-

box cover, and on the 4

sides

Manipulate with great care, do not:

- Rotate core in tray

- Manipulate core without Geologist’s authorization

- Walk on or above Core-box

- Lift or move a core-box alone

- Knock-down a box

Technical log incl. RQD

and Recovery

Adjust geologist depth

Core orientation

Cutting Line

Properly identify the sample

limits on the core and on the

core-box

2. Core Splitting with Diamond Saw

Exploration sample

preparation facility

See SOP Core5

Core Sample 2/2 DH: DD_UMASHAR_002

PQ – Box 13

From 88.3m to 92.7m

To

p

Bo

tto

m

91.1

89.2

Properly label every

Core-Box

Storage in

CoreBox

Shelves

3. Sample dispatch and CoreBox Storage

SOP: CORE5

Sample preparation 1/2 - Flow-Chart

Geological log

Sample Log

Photography

Form:

Storage

Form:

Dispatch Field to Hangar



Manager

Executive Deputy

Manager


ARIAB MINING

COMPANY Ltd

Sample preparation

Standard Operation

Procedures

1. Core Sampling

See Sample prep 1/2

Geologist Supervision

2. Crushing and splitting

Primary Jaw Crusher

2 pass < 2cm

Cone Crusher - Marcy

2 pass < 1 mm

Split

1/8 (~500g)

Split

Split

Splitter:

16 Riffles – 1.4 cm

Ring Mill < 125 µm

3. Grinding

1- 5 kg

Number

SOP: CORE5

Sample preparation 2/2 - Flow-Chart

Form:

Storage

Form:

Shipment Hangar to

External Laboratory

Bulk residue

storage

optional

Split

Preferred procedure

1ry and 2ry crush then split

4-5kg

Storage for further

analysis (375g)

Paper sample bag (125g)

to Intertek

Assay = FA and GA30 etc

Storage of

reference split

Left half

core kept as

a reference

in the core-

box

Hangar Manager Supervision



Manager

Executive Deputy

Manager


ARIAB MINING

COMPANY Ltd

Sample preparation

Standard Operation

Procedures

1. Drilling site Division Geologist Supervision


Number

« Wet »

weight

Ship to the

Hangar

2. Drying

Geological Log

Reference Chips box

Panning

SOP: RC3

Sample preparation - Flow-Chart

External Laboratory

Supervision

Insertion of Standards and Blanks:

- 1 tube

- Label as usual

- No grinding

Form:

Storage

Form:

Shipment Hangar to

external laboratory

Total processing < 125 µm

Assay: Au CN08, Au FA, GA30

Pulp storage at the lab.

Rtn to Hassai after 3 months.

(& Bulk residue discarded.)

Waste7-10 kg

Split 3X

Form:


Wet samples are

sun dried in calico

bags before splitting

Split 3-4X

5 kg0.5 - 1kg

Reference

Storage

Form:

Storage

Storage of

reference

pulp (875g)

Pulp storage

125g pulp



Manager

Executive Deputy

Manager


ARIAB MINING

COMPANY Ltd

Sample preparation

Standard Operation

Procedures

1. Drilling site Division Geologist Supervision


Number

« Wet »

weight

Ship to the

Hangar

2. Drying

Geological Log

Reference Chips box

Panning

SOP: RC4

Sample preparation - Flow-Chart

External Laboratory

Supervision

Insertion of Standards and Blanks:

- 1 tube/sample envelope

- Label as usual

- No grinding

Form:

Storage

Form:

Shipment Hangar to

external laboratory

Total processing < 125 µm

Assay: Au CN08, Au FA, GA30

Pulp storage at the lab.

Rtn to Hassai after 3 months.

(& Bulk residue discarded.)

Waste7-10 kg

Split 3X

Form:


Wet samples are

sun dried in calico

bags before splitting

Split 3-4X

5 kg

0.5 - 1kg

Reference

Storage

Form:

Storage

Storage of

reference pulp

(375-875g)

Pulp storage

125g pulp

Composite sample:

- collected by scoop or splitting

- Number of meters to composite

defined by geologist

5 kg

Bulk composite

sample discarded

qaqc.pdf

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