The Evidence Guide provides advice on assessment and must be read in conjunction with the performance criteria, required skills and knowledge, range statement and the Assessment Guidelines for the Training Package.

Overview of assessment

Critical aspects for assessment and evidence required to demonstrate competency in this unit

Assessors should ensure that candidates can:

recognise hazards and work safely at all times

interpret and closely follow preparation methods

prepare a range of samples that consistently meet client requirements (that is, representative, free of contamination, specified quantity and particle size and ready for analysis)

recognise problems, atypical preparation stages and implement corrective actions

achieve required sample throughput

recognise limitations and seek timely advice

minimise rework, waste and environmental impact

dispose of all waste, surplus and spent samples responsibly.

Context of and specific resources for assessment

This unit of competency is to be assessed in the workplace or simulated workplace environment.

This unit of competency may be assessed with:

MSL924001A Record and present data

MSL943002A Participate in laboratory/field workplace safety.

Resources may include:

a variety of mineral samples

mineral preparation methods

standard operating procedures (SOPs)

mineral preparation equipment, materials and reagents

safety equipment.

Method of assessment

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.

Where applicable, reasonable adjustment must be made to work environments and training situations to accommodate ethnicity, age, gender, demographics and disability.

Access must be provided to appropriate learning and/or assessment support when required.

The language, literacy and numeracy demands of assessment should not be greater than those required to undertake the unit of competency in a work like environment.

This competency in practice

Industry representatives have provided the case study below to illustrate the practical application of this unit of competency and to show its relevance in a workplace setting.

Mineral processing

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 sub-sample 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.

Required skills

Required skills include:

using preparation equipment

recognising hazards and working safely at all times

interpreting and following preparation methods

recognising problems and implementing corrective actions

recognising limitations and seeking timely advice

minimising rework, waste and environmental impact

Required knowledge

Required knowledge includes:

geological properties of common samples, such as sulphides, oxides and silicates

terminology, such as homogeneous, heterogeneous, integrity and 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 and equilibria

tracking analytes of interest during changes of state

safety information, such as material safety data sheets MSDS

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, and conversions

enterprise and/or legal traceability requirements

relevant health, safety and environmental requirements

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Codes of practice

Where reference is made to industry codes of practice, and/or Australian/international standards, it is expected the latest version will be used.

Standards, codes, procedures and/or enterprise requirements

Standards, codes, procedures and/or enterprise requirements may include:

Australian and international standards, such as:

AS 1199 Sampling procedures and tables for inspection by attributes

AS 1678 Emergency procedure guide -Transport

AS 1940-2004 Storage and handling of flammable and combustible liquids

AS 3780-2008 The storage and handling of corrosive substances

AS 3988-1991 Copper, lead, zinc, gold and silver ores - Guide to sample preparation for the determination of gold

AS 4433.2-1997 Guide to the sampling of particulate materials - Preparation of samples

AS ISO 1000-1998 The international system of units (SI) and its application

AS/NZS 4452:1997 The storage and handling of toxic substances

enterprise recording and reporting procedures

equipment startup, operation and shutdown procedures

MSDS

national measurement regulations and guidelines

principles of good laboratory practice (GLP)

production and laboratory schedules

quality manuals, equipment and procedures manuals

standard operating procedures (SOPs) and published preparation methods

Samples

Samples may include:

solids, such as rocks, minerals, soils, sands and stream sediments

core and other drill samples (e.g. rotary air blast (RAB), reverse circulation (RC) and aircore)

slurries, powder concentrates and metallurgical solutions

dump samples and grab samples

Client requests/documentation

Client requests/documentation may include:

client profile, sample identification and sample receipt

preparation methods, storage and analyses required

service charges

Preparation methods

Preparation methods may include:

sorting, boxing and drying

sieving

primary crushing (e.g. 10 mm, 2 mm)

fine pulverising (e.g. 100 micron, 75 micron)

partial digestion requiring separation (e.g. aqua regia)

complete digestion (e.g. multi-acid digest)

non-destructive (e.g. LIF, Li2B4O7 disks)

solvent extraction (e.g. di isobutyl ketone dibK)

Preparation equipment

Preparation equipment may include:

splitters (e.g. riffles and rotary dividers)

mills (e.g. ball, ring and rod)

bowls (e.g. chrome-steel, tungsten-carbide and zirconia) and tumblers

crushers (e.g. cone, jaw and roll), grinders and disc pulverisers

sieves

ovens, muffle furnaces, hot plates and microwave ovens

ultrasonic baths

centrifuges and vacuum and pressure filtration

volumetric glassware/plastic ware and dispensers

analytical balances

auto-samplers

sample containers and labels

Hazards

Hazards may include:

asbestiform minerals, dust, silica and fibrous samples

chemicals, such as hydrofluoric acid, bromine, perchloric acid, aqua regia, cyanide, lead-based compounds, free-mercury and nickel compounds

noise and vibration

crushing, entanglement and cuts associated with moving machinery

manual handling of heavy loads, such as sample bags

heat, exhaustion, stress and fatigue

Safety equipment and hazard control measures

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 and fume hoods

guards for moving machinery parts

noise insulation

using personal protective equipment, such as masks, gloves, boots, goggles, coats, ear muffs and 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 and 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

Critical preparation steps that determine analytical accuracy and precision may include:

monitoring drying (incipient and total)

mixing to ensure homogeneity before sub-sampling

suitability of reagents for purpose (e.g. dryness)

accurate operation of dispensers and balances

critical/non-critical volumes and 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/plastic ware and filtering)

Occupational health and safety (OHS) and environmental management requirements

OHS and environmental management requirements

all operations must comply with enterprise OHS and environmental management requirements, which may be imposed through state/territory or federal legislation - these requirements must not be compromised at any time

all operations assume the potentially hazardous nature of samples and require standard precautions to be applied

where relevant, users should access and apply current industry understanding of infection control issued by the National Health and Medical Research Council (NHMRC) and State and Territory Departments of Health