Elements and Performance Criteria

The range of variables relates to the unit of competency as a whole. It allows for different work environments and situations that will affect performance.
Where reference is made to industry Codes of Practice, and/or Australian/international standards, it is expected the latest version will be used.
All operations must comply with relevant standards, appropriate procedures and/or enterprise requirements.

These procedures include or have been prepared from
Australian and international standards, such as -
AS4433.2 Guide to the sampling of particulate materials - Preparation of samples
AS3988 Copper, lead, zinc, gold and silver ores - Guide to sample preparation for the determination of gold
Codes of Practice, such as GLP and GMP
material safety data sheets (MSDSs)
standard operating procedures (SOPs) and published preparation methods
quality manuals, equipment and procedures manuals
equipment startup, operation and shutdown procedures
enterprise recording and reporting procedures
production and laboratory schedules.

Samples may include
solids, such as rocks, minerals, soils, sands, stream sediments
core and other drill samples, such as RAB, RC, aircore
slurries, powder concentrates, metallurgical solutions
dump samples, grab samples.

Client requests/documentation may include
client profile, sample identification and sample receipt
preparation methods, storage and analyses required
service charges.

Preparation methods may include
sorting, boxing and drying
sieving
primary crushing (for example, 10mm, 2mm)
fine pulverising (for example, 100 micron, 75 micron)
partial digestion requiring separation (for example, aqua regia)
complete digestion (for example, multi-acid digest)
non destructive (for example, LIF, Li 2B 4O 7 disks)
solvent extraction (for example, di isobutyl ketone dibK).

Preparation equipment may include
splitters (for example, riffles, rotary dividers)
mills (for example, ball, ring, rod)
bowls (for example, chrome-steel, tungsten-carbide, zirconia) and tumblers
crushers (for example, cone, jaw, roll), grinders, disc pulverisers
sieves
ovens, muffle furnaces, hot plates, microwave ovens
ultrasonic baths
centrifuges, vacuum and pressure filtration
volumetric glassware/plasticware, dispensers
analytical balances
autosamplers
sample containers, labels.

Hazards may include
asbestiform minerals, dust, silica, fibrous samples
chemicals, such as hydrofluoric acid, bromine, perchloric acid, aquaregia, cyanide, lead-based compounds, free-mercury, nickel compounds
noise, vibration
crushing, entanglement, cuts associated with moving machinery
manual handling of heavy loads, such as sample bags
heat, exhaustion, stress, fatigue.

Safety equipment and hazard control measures may include
ensuring assess to service shut-off points
recognising and observing hazard warnings and safety signs
labelling of samples, reagents and hazardous materials
direct extraction, fumehoods
guards for moving machinery parts
noise insulation
using personal protective equipment, such as mask, gloves, boots, goggles, coats, ear muffs, safety boots
following established manual handling procedures
regular cleaning of equipment and work areas using enterprise procedures
antidotes for specific hazards, such as hydrofluoric acid, cyanide
reporting of abnormal emissions, discharges and airborne contaminants, such as noise, light, solids, liquids, water/waste water, gasses, smoke, vapour, fumes, odour and particulars to appropriate personnel.

Critical preparation steps that determine analytical accuracy and precision may include
monitoring drying (incipient, total)
mixing to ensure homogeneity before subsampling
suitability of reagents for purpose (for example, dryness)
accurate operation of dispensers and balances
critical/non critical volumes, critical reagent quantities
temperature control during digests
loss of solution prior to/after mixing
type and acid strength in final solutions
mechanical loss of digest (sputtering, residues on glassware/plasticware, filtering).

Health, safety and environment
All operations to which this unit applies are subject to stringent health, safety and environmental (HSE) requirements, which may be imposed through State or Federal legislation, and these must not be compromised at any time. Where there is an apparent conflict between performance criteria and HSE requirements, the HSE requirements take precedence.
All operations assume the potential hazardous nature of samples and require standard precautions to be applied. Users should access and apply current industry understanding of infection control issued by the National Health and Medical Research Council and State and Territory Departments of Health. All operations are performed in accordance with standard operating procedures.

The Evidence Guide describes the underpinning knowledge and skills that must be demonstrated to prove competence.
Critical aspects of competency

Competency must be demonstrated in the ability to perform consistently at the required standard. In particular, assessors should look to see that the candidate:

recognises hazards and works safely at all times
interprets and closely follows preparation methods
prepares a range of samples that consistently meet client requirements (that is, representative, free of contamination, specified quantity and particle size, ready for analysis)
recognises problems, atypical preparation stages and implements corrective actions
achieves required sample throughput
recognises limitations and seeks timely advice
minimises rework, waste and environmental impact
disposes of all waste, surplus and spent samples responsibly.

Underpinning knowledge

Competency includes the ability to apply and explain:

geological properties of common samples, such as sulphides, oxides, silicates
terminology, such as homogeneous, heterogeneous, integrity, segregation
distribution of common analytes in a matrix
chemical reactions associated with common preparation methods, effects of reagents on the element of interest
reaction and recovery rates, solubility, equilibria
tracking analytes of interest during changes of state
safety information (for example, MSDSs)
function of key equipment components and principles of operation
calculation steps in preparation methods (for example, serial dilution)
non SI units (ppm, ppb) and SI units, conversions
enterprise and/or legal traceability requirements
relevant health, safety and environmental requirements.

Assessment context and methods
This unit of competency is to be assessed in the workplace or simulated workplace environment.

The following assessment methods are suggested:

sizing checks and grind performance for samples prepared by candidate
review of preparation and production documentation prepared by the candidate
review of quality control performance and analytical results traceable to samples prepared by the candidate
written/oral questioning about preparation methods, critical steps, typical problems and corrective actions
feedback from peers clients and supervisors.
In all cases, practical assessment should be supported by questions to assess underpinning knowledge and those aspects of competency which are difficult to assess directly. Questioning techniques should suit the language and literacy levels of the candidate.

Interdependent assessment of unit

This unit of competency may be assessed with:

PMLOHS302A Participate in laboratory/field workplace safety
PMLDATA200A Record and present data.

Resource implications

Resources may include:

a variety of mineral samples
mineral preparation methods, standard operating procedures
mineral preparation equipment, materials, reagents
safety equipment.

This competency in practice
A mining company provides a drill-core sample to a laboratory to determine its gold content as part of the company's resource estimation. A technician receives the sample and registers the details from the client specification sheet. He/she confirms that a 100g (75 micron) analytical portion is required with the coarse split to be retained for possible future testing. Noting from the sheet that the sample is likely to contain high levels of free gold, the technician carefully segregates it from all other samples. After drying and crushing the sample, the technician splits the coarse material and pulverises a subsample to the required particle size. He/she places it in a labelled packet and presents it to the assay section. The technician carefully cleans all the equipment used during processing the sample to prevent cross contamination of samples.

The seven key competencies represent generic skills considered for effective work participation. The bracketed numbering against each of the key competencies indicates the performance level required in this unit. These are stand-alone levels and do not correspond to levels in the Australian Qualifications Framework (AQF).
Level (1) represents the competence to undertake tasks effectively
Level (2) represents the competence to manage tasks
Level (3) represents the competence to use concepts for evaluating and reshaping tasks.
Communicating ideas and information
(2)

Collecting analysing and organising information
(2)

Planning and organising activities
(2)

Working with others and in teams
(2)

Using mathematical ideas and techniques
(2)

Solving problems
(2)

Using technology
(2)