Challenge of Developing ISO Sampling Standard Ralph Holme CSIRO Mineral Down Under Flaghip Chair ISO/TC 10/SC 1 Sampling Iron Ore Chair ISO/TC 7/SC 4 Sampling Coal and Coke Convenor ISO/TC 183/WG 9 Sampling Cu, Pb, Zn and Ni Concentrate
Introduction Standard developed by the International Standard Organiation (ISO) for ampling mineral commoditie are criticied for not being adequate and conforming to Pierre Gy theory of ampling I thi fully jutified? Alway cope for improving ISO ampling tandard, but many element of the theory of ampling and the requirement for correctly deigning ample cutter are incorporated into current ISO tandard for ampling key mineral commoditie, ie, iron ore, coal and coke, and bae metal Thee tandard are continually being reviewed and improved Difficult tak, becaue they are developed by technical committee on an international conenu bai Commercial iue or ignorance can get in the way of correctne Introduction and adoption of new concept and procedure take time Peritence uually pay off, particularly if change backed up by hard data Bad ISO tandard are being dicontinued, eg, ISO 1988 for coal
ISO Standard Development Technical Committee etablihed to develop tandard for pecific commoditie, eg: ISO/TC 7 (Solid mineral fuel) ISO/TC 10 (Iron ore) ISO/TC 183 (Copper, lead, zinc and nickel ore and concentrate) Sub-committee and Working Group et up to develop pecific tandard for ampling, analyi, phyical teting, etc Countrie participating in the development of thee tandard nominate repreentative to thee Sub-committee and Working Group Draft tandard progre through a number of tage: Working Draft (WD) Committee Draft (CD) Draft International Standard (DIS) Final Draft International Standard (FDIS) Publication a an International Standard
Key Requirement for Correct Sampling The key requirement for enuring that the ample collected from a proce tream are repreentative and that the overall preciion i adequate are a follow: The number of increment taken from the proce tream mut be ufficient to obtain the deired ampling and overall preciion All particle in the proce tream or tratum mut have an equal probability of being elected and appearing in the final ample for analyi For a given nominal top ize of the material being ampled, there i an abolute minimum ma of ample that mut be retained after diviion to control the fundamental ampling error at each ampling tage and obtain the deired diviion preciion (Gy, 198) If thee key requirement are incorporated into ISO tandard for ampling mineral commoditie, then the tandard goe a long way toward conforming to correct ampling principle and providing repreentative ample
Component of Sampling Error A number of ISO tandard developed recently for copper, lead, zinc and nickel concentrate lurrie (ISO 11794) and coal lurrie (ISO 0904) tart off by explicitly outlining all the component of the overall ampling error TSE defined by Gy a follow: TSE = FE + GE + QE + QE 3 + WE + DE + EE + PE where FE = fundamental error GE = grouping and egregation error QE = long-range quality fluctuation error QE 3 = periodic quality fluctuation error WE = weighting error DE = increment delimitation error EE = increment extraction error PE = preparation error The error component are then dicued in detail
Component of Sampling Error Error component that lead to bia need to be eliminated Acceory error Delimitation and extraction error Weighting error Other need to be reduced to achieve acceptable preciion Fundamental, grouping and egregation error Long-range quality fluctuation error Periodic quality fluctuation error Minimiing or eliminating bia i critical, becaue bia cannot be eliminated once it i preent no point in being preciely incorrect Source of bia that can be eliminated Incorrect delimitation and extraction of increment Sample pillage and contamination Source of bia that need to be minimied Change in moiture content, dut lo, etc
Sampling Preciion Several approache are ued for determining the overall variance in ISO tandard for ampling key mineral commoditie The mot comprehenive approach i decribed in ISO 1743 for ampling copper, lead, zinc and nickel concentrate, where the overall variance i expreed a: T S A When replicate analye are carried out: A T S r In ISO 1743, the ampling variance i broken up into it component for each ampling tage a follow: T S... 1 S... i S u 1 r A
Sampling Preciion The ampling tage approach i particularly ueful for deigning and aeing ampling cheme To obtain the maximum benefit, the variance between increment for each ampling tage need to be determined uing the following equation provided in ISO 1743: The ampling variance for tage i i then given by: The overall variance i then given by: 1 1 ) ( PA i n j j b n x x i i b S n i i r n A u i i b T i 1 1
Sampling Preciion The ampling tage approach i a comprehenive approach to deigning a ampling cheme and determining the overall variance, although quite a lot of work i involved A impler approach ued in ISO 308 and ISO 13909- for ampling iron ore and coal and coke repectively i to break up the overall variance into the primary ampling, ample proceing and analytical variance only a follow: A T S 1 P r The primary ampling variance i determined uing a imilar proce to that ued in the ampling tage method The ample proceing variance i uually determined experimentally by proceing duplicate ample
Sample Cutter Deign Requirement Incorrect Incorrect The dicharge end of a conveyor i the bet location The cutter mut take a complete tream cro-ection The cutting time at each point mut be equal The cutter hould interect the tream in a plane normal to the tream trajectory The ample cutter mut be non-retrictive, elfclearing and dicharge completely each increment The plane of the cutter aperture mut not be vertical The cutter aperture mut be at leat 3d The cutter peed mut be uniform and mut not exceed 0.6 m/ unle the cutter aperture exceed 3d Bucket-type cutter mut have ufficient capacity Material from belt craper mut be ampled No contamination of the ample or change in quality
Sample Cutter Deign ISO 1743 (Concentrate) There hall be no impediment to the flow of concentrate into the cutter at the maximum flow rate of the concentrate. ISO 308 (Iron ore) There hall be no impedance to flow of ample material through the ample cutter at the maximum flow rate. The cutter hall be of the elf-clearing type, eg, tainle teel or polythene lined, dicharging each increment completely. There hall be no clogging or retention of reidual material in the ample cutter, ie, the cutter hall be elf-clearing. Correct Incorrect - Sample reflux Dicharge chute angle hall be a minimum of 60 to the horizontal. No material other than the concentrate ample hall be introduced into the cutter, eg, dut mut be prevented from accumulating in the cutter when in parked poition. There hall be no ignificant change in the quality of the ample while taking increment, eg, degradation of the contituent particle if the ample i taken for ize determination or change in moiture content if the ample i taken for moiture determination. There hall be no contamination or introduction of material other than the ample into the ample cutter.
Sample Cutter Deign ISO 1743 (Concentrate) The cutter hall collect a complete croection of the concentrate tream, both the leading and trailing edge completely clearing the tream at the two limit of the cutter path. The cutter hall interect the concentrate tream either in a plane normal to, or along an arc normal to, the mean trajectory of the tream. ISO 308 (Iron ore) The ample cutter hall take a complete cro-ection of the ore tream, both the leading and trailing edge clearing the tream in one path. The ample cutter hall interect the ore tream either in a plane perpendicular to or along an arc normal to the mean trajectory of the tream. Incorrect Correct The cutter hall travel through the concentrate tream at a uniform peed, not deviating by more than 5% at any point. The geometry of the cutter opening hall be uch that the cutting time at each point in the tream i equal, not deviating by more than 5%, ie, traight path cutter hall have parallel cutter lip and radial cutter hall have radial cutter lip. The ample cutter hall travel through the ore tream at a uniform peed, not deviating by more than ±5% at any point. The geometry of the cutter aperture hall be uch that the cutting time at each point in the tream i equal, not deviating by more than ±5%, eg, traight-path cutter hall have parallel cutter lip and rotary cutter hall have radial cutter lip.
Sample Cutter Deign Incorrect Incorrect ISO 1743 (Concentrate) The cutting aperture of the cutter hall be not le than 30 mm or, if agglomerate are preent, three time the nominal top ize of the concentrate, whichever i larger, noting that the cutter aperture may need to be increaed above 30 mm if blockage occur for wet concentrate. The maximum cuter peed hall 0.6 m/ unle the cutter aperture i increaed above the minimum of 3d in accordance with the equation derived by Gy and Marin. Bucket cutter hall be of ufficient capacity to accommodate the increment ma obtained at the maximum flow rate of the concentrate. ISO 308 (Iron ore) The cutting aperture of the primary ampler hall be at leat three time the nominal top ize of the ore, or 30 mm, whichever i the greater. However, with certain ore, eg, ticky ore, bridging and conequent bia may occur for a cutter aperture of three time the nominal top ize. In thee intance, larger cutter aperture hall be ued to prevent the introduction of ignificant bia. The maximum cuter peed hall 0.6 m/ unle the cutter aperture i increaed above the minimum of 3d in accordance with the equation derived by Gy and Marin. Bucket type cutter hall be of ufficient capacity to accommodate the increment ma obtained at the maximum flow rate of ore.
Sampling from Wagon and Stockpile Sampling from wagon can only be conducted if a full vertical column i extracted Sampling of tockpile not permitted Correct Incorrect Incorrect
Fundamental Error and Minimum Ma The fundamental error variance FE identified by Gy i due to the particulate nature of the material being ampled and i given by: σ FE 3 Cd a m S where C = ampling contant d = nominal top ize (cm) m S = divided ample ma (g) a = fractional concentration The fundamental error lead to the minimum ample ma to achieve the required preciion by tranpoing the above equation: m S Cd 3 a FE
Minimum Sample Ma The ample ma cannot be reduced below the minimum ample ma for a given preciion until the ample i cruhed Thi i a critical ampling requirement that mut not be ignored if good diviion preciion i required While the minimum ample ma can be calculated, it can alo be determined experimentally Tet program have been conducted by everal ISO ubcommittee to etablih the minimum ample ma a a function of nominal top ize and required preciion a follow: ISO/TC 7/SC 4 (Sampling coal and coke) ISO/TC 10/SC 1 (Sampling iron ore)
Minimum Sample Ma For iron ore (ISO/TC 10/SC 1), a comprehenive international tet work program wa conducted, the main contributor being: Autralia, Brazil and Japan The following equation for minimum ample ma m S (in kilogram) a a function of diviion preciion D (in % Fe) wa ubequently developed for iron ore baed on Gy equation: m S 0.0003 d σ D.5 where d = nominal top ize (mm) Incorrect Thi equation i included in ISO 308 for ampling iron ore, which tate clearly that the ample ma cannot be reduced below thi minimum until the ample i cruhed
Minimum Sample Ma Example of the minimum ma of divided ample for iron ore uing thi equation are provided in ISO 308 Nominal top Minimum ma of divided gro ample (kg) ize (mm) σ D = 0.1% Fe σ D = 0.05% Fe 40 35 1,300 31.5 180 710.4 75 300 10 10 40 6.3 3. 13.8 0.5 1.7 1.4 0.5 0.5 0.50 0.5 0.5 0.5 0.5 0.5 The mae pecified in ISO 308 are conervative, becaue the ISO tandard i deigned to cover iron ore from around the world The comparable minimum ma table for ampling coal are only partially baed on experimental data, but the mae are conervative
Sytem Verification The latet ISO tandard included check lit for confirming the compliance of ample cutter, including: Cutter peed Uniformity of cutter peed while cutting the ore tream Number of cut Size and geometry of cutter aperture Worn and/or miing cutter lip Build-up and/or blockage in cutter aperture and chute Reflux from cutter aperture Ingre of extraneou material when the cutter i parked Hole in chute and bin reulting in ample lo Increment/ample ma Particle ize Worn Cutter Aperture Hole in Chute Partially Blocked Cutter
Concluion The principal apect of the theory of ampling and the requirement for correctly deigning ample cutter have been incorporated into key ISO tandard for ampling mineral commoditie, including: Iron ore Coal and coke Copper, lead, zinc and nickel concentrate Thee tandard play an important part in international trade However, there i alway cope for improvement Developing new and improving exiting tandard i not an eay tak Standard are developed by ISO technical committee on a conenu bai Reaching international conenu i an ongoing challenge Important for thoe with a good knowledge of correct ampling practice to maintain their involvement in ISO committee on a long term bai Peritence pay off Don t give up!!
Invitation to Sampling 01 Date: 1- Augut 01 Hyatt Hotel, Perth, Autralia Abtract due by 14 November 011 Development and application of ampling theory Drill and blathole ampling Plant ampling Sampling for blending, quality control and metallurgical accounting Sampling of commodity export New development in ampling and ample preparation equipment Maintenance of ampling equipment and training Development of national and international tandard Cae tudie of the application of ampling in exploration, mining, mineral proceing and environmental monitoring. http://www.auimm.com.au/ampling01/
ISO/TC 10/SC 1 ISO/TC 10/SC 1 Committee Thank you ISO/TC 183