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IS 15765 (2008): Method of sampling ferro alloys for sieveanalysis and size determination [MTD 5: Ferro Alloys]

April 2008

IS 15765 : 2008

'J.fl'< rfJ l/ JtFtCfj

c1T5 Pi~ cpr~~ 3iR~~cf>~~AAcBT~

Indian Standard

METHOD OF SAMPLING FERROALLOYS FOR SIEVE ANALYSIS AND

SIZE DETERMINATION

ICS 77.100

OBIS 2008

BUREAU . O F INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Ferro Alloys Sectional Committee, MTD 5

FOREWORD

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the Ferro AlloysSectional Committee had been approved by the Metallurgical Engineering Division Council.

', This standard covers the sampling of ferro alloys for sieve analysis and particle size determination. Sampling offerro alloys for chemical analysis is separately covered in IS 1472 : 1977 ' Methods for sampling ferro alloys fordetermination of chemical composition'.

Ferro alloys are generally supplied in containers, drums or bags. Sampling shall be carr ied out at the time ofloading or unloading or during packing/unpacking or from a stockpile . For the purpose of sampling the ferroalloys according to size to be divided in two groups, that is, lump form and crushed form. Devices and tools forsampling and sample preparations are covered in Annex A.

In reporting the results of a test or analysis made in accordance with this standard, if the final value, observed orcalculated, is to be rounded off, it shall be done in accordance with IS 2 : 1960 'Rules for rounding offnumerical valves (revised)' .

IS 15765: 2008

Indian Standard

METHOD OF SAMPLING FERROALLOYS FOR SIEVE ANALYSIS AND

SIZE DETERMINATION

IS No.

1472 : 1977

I SCOPE

This standard lays down the procedure to be followedfor collection and preparation of samples representinga lot of ferro alloys, namely, ferro manganese, ferrochrome, ferro silicon, silico-manganese, etc, in bulkor in packed form for sieve analysis and sizedetermination.

NOTE- Forthepurposeofsampling theferro alloys according10size may be divided into two grouPS. that is. lump form IIIdcrushedform.

2 REFERENCE

The following standard contains provision, whichthrough reference in this text constitutes provision ofthis standard. At the time of publication, the editionindicated was valid. All standards are subject torevision and parties to agreements based on thisstandard are encouraged to investigate the possibilityof applying the most recent edition of the standardindicated below:

TItle

Method for sampling ferro alloysfor determination of chemicalcomposition

3 TERMINOLOGY

For the purpose of this standard the followingdefinitions shall apply.

3.1 Consignment - A consignment may consist ofone or more lots and sub-lots.

3.2 Crushed Form - Particles below 50 mm.

3.3 Gross Sample - The sample obtained bycombining together all the increments from sub-lots.There will be as many gross samples as the number oflots.

3 .4 Hand Placing or Manual Single BodyScreening - In case of large lump size pieces, eachpiece is contacted to the aperture of the screen byhand for its possibility of passing through theprescribed square hole aperture screen.

3.5 Increment - The quantity of ferro alloys obtainedby sampling device at one time and in one motion froma sub-lot.

3.6 Lot - The quantity of the ferro alloy ofone typeand grade offered for inspection at one time.

3.7 Lump Form - Particles of size, 50 mm and above.

3.8 Manual Screening - It is a screening operationin which the sieve is shaken manually.

3.9 Mechanical Sieving - An operation in whichthe sieve is supported and shaken mechanically.

3.10 Nominal Top Size - The upper level of theparticle size ranges specified for technicalrequirements and conditions for delivery ofindividual types of ferro alloys.

3.lJ Screening (Sieving) - It is process ofoperation where the samples are separated accordingto the specified particle size by using one or moresieves.

3.12 Size Fraction or Particle Size - Duringscreening operation with one (say 'X') sieve theparticles which are passing through that 'X' sieve aredesignated as '- X' size particles and which are retainedwill be designated as '+X' size. Similarly if two sieves(say 'X' and 'r) are used, particles retained on sieveare designated as '+ X'. Particles passing throughand retained on 'r sieve are called as '- X' and + 'rsize. Particles passed through 'Y' sieve are designated'-r size.

3.13 Size Sample - A sample taken for determinationofgranulometric composition ofa consignment or partof a consignment.

3.14 Sub-lot - The quantity of ferro alloy in one ofthe various parts into which the lot is divided for thepurpose of sampling. .

3.15 Top Size - Particles of size expressed by theoperative size of a sieve on which not more thanone percent of the sample is retained.

4 SAMPLING

4.1 General Rules

4.1.1 General rules of sampling are similar to that asprescribed in IS 1472.

4.1.2 Sampling for determination of ferro alloys forparticle size is different from the sampling for chemicalanalysis.

4.1.3 Sampling shall be carried out at the time ofloading or unloading or during packing/unpackingor from a stockpile.

4.1.4 Some ofthe ferro alloys are friable in nature and

IS 15765: 2008

they should be handled properly. Hence, samples forsize analysis should be drawn and subjected to sievetest of only such places, which involve minimumfurther handling.

4.1.5 The ferro alloys are generally delivered dulypacked in containers, bags or drums. Similar type ofmaterials packed in similar containers shall begroupedas one lot.

4.1.6 'Wht:Jl material in bulk is supplied in trucks orwagons or by any other means the total consignmentshall be taken as one lot.

4.1.7 If the mass of consignmentllot is more than2 000 mt and mass is not homogenous in size, sub­lots/sub-consignment sampling is advisable forattaining higher precision. Such consignment or lotmay be divided arithmatically into sub-consignment/sub-lot for sampling purpose such that each sub­consignment or sub-lot should not be more than 2 000~t and sampling plan shall be carried out assumingeach sub-consignment or sub-lot as a consignment ora lot . The analysis result of each sub-lot/sub­consignment shall be compiled together for getting theresult of a consignmentllot.

5 GROSS SAMPLE QUANTITY

Gross sample quantity is governed by mass ofincrements and number of increments.

5.1 Mass of Increment

The minimum mass of increment to be taken fromlot/sub-lot shall be governed by the nominal topsize as specified in Table I .

5.2 Number of Increments

The number of increments to be taken from a lot/sub­lot shall be governed by the mass of the consignmentas specified in Table 2.

5.3 Collection of Increments

5.3.1 Incrementsfrom Containers

One in every five containers, bags/drums shall beunloaded on a levelled ground from each lot/sub-lot,spread evenly to the height of the maximum size ofparticles in the lot being inspected . As it is very difficultto use sampling scoop for lump form owing to its sizeand heaviness , square frame shall be used in its place.The scoop/square frame used for sampling shall havethe dimension as per Annex A.

5.3.1.1 Lumpform

1."e square frame with each side equal to at least 3times the largest particle or lump size of the materialshall be placed at random at one point

All these pieces which are completely inside the frame

2

and more than 50 percent will be collected as oneincrement.

5.3.1.2 Crushed form

Increment shall be collected at different spots by asampling scoop from the spread material. Totalmaterial collected in a scoop shall fonn one increment.

5.3.2 Increments from WagonslTruclcs in Bulk

5.3.2.1 Lump form

Material shall be evenly spread in the wagon/truck.On the top of the levelled material square frame shallbeplaced at random across the surface and the materialshall be collected down to the bottom as describedunder 5.3.1.1 as one increment.

5.3.2.2 Crushed form

Material shall be evenly spread in the wagon/truck.Increments shall be collected at different spots by asampling scoop. Total material collected in a scoopshall form one increment.

5.3.3 Increments from Stockpiles

Based on the size ofthe stack number ofspots shall beselected in a definite order on surface to make pitswith minimum dia of0.5 m. On each side of the stackone or two spots shall be selected depending on itslength and breadth to make trenches ofminimum depthof0.5 m.

5.3.3.1 Lumpform

The entire material from all the pits and trenches iscollected, spreaded evenly on a levelled ground tothe height of the maximwn size of the particles in thestack and a minimum required sample shall becollected as detailed under 5.3.1.1.

5.3.3.2 Crushed form

The entire material from all the pits and trenches iscollected and spread evenly on a levelled ground tothe height of the maximum size of the particles in thestack and minimum required sample shall becollected with help of a sample scoop and scrapper.If the square frame is used then place the squareframe on the top of the levelled material at randomat one point All these pieces which are completelyinside the frame and more than 50 percent inside theframe and down to the bottom shall be collected asonce increment.

5." From each lot/sub-Iot the number of incrementsshan be collected as per Table 2.

6 PROCEDURE FOR SIEVE ANALYSIS

6.1 Square hole aperture sieves shall be used onlyunless otherwise specified.

IS 15765: 2008

18ble 1 Mass or an Increment(Clause 5.1)

SI Nomi••1Top SIze M.... kgNo. J.-.r "'rrm Group i Group2 Group3

(i) (2) (3) (4) (5)

i) 315 337 81

ii) 200 164 46

iii) 150 104 32

iv) 100 79 55 19

v) 75 48 35 13

vi) 50 24 18 8

vii) 35 13 10 S

viii) 25 7 8 3

ix) 10 I.S 1.4 1.1

x) 6.3 0.7 0.7 0.6

xi) 3.15 0.3 0.3 0.3

xii) 2 0.3 0.3 0.3

Group 1-FeW,FeMo, FeNb

Group2 - FcCr,FcSiCr,FeMn,FeTi,Fcnb,FcSihaving. siliconcontent less than4S pcn:cnt,Milt

Group3 - FeB,SiCa, FcSiCa,FcSihaving. siliconcontentequalto or grclItcr than45 percent, Milt

NOTE- Forarrivingat massofincremcnt forotherNominalTopSizes(NTS) the followingformulamay be used:

a) Group i Alloys

b) Group2 Alloys

c) Group 3 Alloys

Massofinc:remcnt, q

Massofinc:remcnt,q

Massofinc:remcnt, kg

3

450

(3001NTS)'"

300

(3001NTS)U

80

(3001NTS)'U

IS 15765 : 2008

7 REPEATABILITY

sample to determine the size distribution of aconsignment as per the equation given below:

/ = content of a fraction, as percentage by mass;

ml

= mass, of a fraction in a charge in kg; and

m = mass of total fraction, in kg.

At least two analysis to be carried out. Thecorresponding fraction (F) should not be more than'X percent' where 'X' = 0.2 F, Min with a minimumvalue of two percent. 'X' is the maximum permissibledifference between corresponding fraction massesof two analysis of sample of the same material,expressed as percentage. 'F, Min' is the smaller ofthe two corresponding fractions 'P expressed as amass percentage.

m

m. x 100/ =

where

6.2 Sieve analysis of ferro alloys susceptible tobreakage through handling shall be carried out nearthe place of sampling.

6.3 A sample for sieve analysis may be divided intofractions of large lump size and the rest by handseparation. Duringsieve analysis same size lumps shallbeseparated by hand from the screen.

6.3.1 Large Size Lumps

The large size lumps (see 3.6 and Table 3) may beexamined by the method of manual single bodyscreening (see 3.10). The pieces, passed through thesieve in anyone direction shall be treated as withinthe specified size subject to the dimension notexceeding 1.15 times the size range specified in twoor three directions. Otherwise that particle wi11 betreated as oversize.

6.3.2 Mechanical sieving (see 3.15 and Table 3) canbe carried out for crushed form only and the uppersieve shall be charged such that a layer of thicknessshould not bemore than the aperture of top size ofthesieve.

6.3.3 The fraction remaining on each sieve shall beweighedseparately. The mass ofeach fraction shall becalculated as percentage of initial mass of the test

8 REPRODUCIBILITY

As specified by the interested parties or on mutualagreement between the supplier and the purchaser.

Table 2 Minimum Number of Increments to be Collected

(Clauses 5.2 and 5.4)

Sl

No.

(I)

i)

ii)

iii)

iv)

v)

vi)

vii)

viii)

ix)

x)

xi)

MassofCoDligDlllmt

mtAr "Over Upto and Including

(2) (3)

5000 10000

2500 5000

1000 2500

500 1000

250 500

100 250

50 100

25 50

10 25

5 10

5

Minimum Number of

Increments

(4)

33

30

28

25

2J

20

18

15

10

8

6

4

IS IS76S: 2008

Table 3 Quantity of Material Taken at One Time in Sieve for Screening

(Clauses 6.3.1 and 6.3.2)

51 Siu,nun Area 2 02!l em'

No.

(1) (2) (3)

i) 50-100 10 kg

ii) 25 -50 Skg

iii) 10 -25 Hg

iv) Below 10 2kg

ANNEX A

(Foreword, and Clause 5.3.1)

DEVICES AND TOOLS FOR SAMPLING AND SAMPLE PREPARATION

A-I For mechanical sampling, only mechanicaldevices meeting the following requirements shall beused:

a) A sampling device shall cross the entire streamof ferro alloy and take a complete cross­section,

b) The capacity of the sampling device shall besufficient to take one complete increment at onecut, and

c) The construction of a sampling device shall beconvenient for cleaning and checking.

A-2 The following implements shall be used formanual sampling:

a) Scoops,

b) Containers for sampling, and

c) Probes.

A-2.t A scoop for increment sampling shall be ofdimensions corresponding to the increment volumesand shall be sufficiently durable (see Fig. I andTable 4). Examples for choosing scoops are givenbelow:

a) Determine experimentally, or based on previousexperience or on the data provided, the bulkdensity, p, ofa ferro alloy, inkilograms per cubicmetre. This will depend on the particle size andferro alloy grade;

b) Calculate the volume, VI ' of an increment, incubic metre, using the following equation:

5

where

m. = mass, of an increment in kg;

p = bulk density of the ferro alloy, inkg! m': and

c) Using Table 4, select a scoop the volume ofwhich is nearest to the volume obtainedaccording to (b) above.

A-2.2 A container for increment sampling shall beselected on the basis of the volume of a sample(see Fig. 2 and Table 5).

A-2.3 The diameter of the opening of a probe forincrement sampling of a consignment of a ferro alloyof less than 10 mm in particle size shall be not lessthan three times the normal top size. The constructionofthe probe shall ensure sampling from the whole layerof ferro alloy. Examples of probe constructions aregiven in Fig. 3.

A-2.4 The devices for crushing of samples shallbe selected in accordance with the planned particlesize and the hardness of the ferro alloy.

A-2.S A divider for sample division shall be selectedon the basis of the particle size in accordance withTable 6.

A-2.6 Devices and tools used for sampling and samplepreparation shall ensure the planned precision at allthe stages of the procedure.

A-2.7 All the devices and tools used shall be cleaned ,checked and adjusted before sampling.

Table 4 Recommended Dimensions of Scoops for Increment liampling -rI)

....(Clause A-2.1) VI.....

CI'IVI

SI Number or Approximate Dimeoslons,mm Material ale ble N

No. Seoop Volume Thlcknellg

-A-. QO

em' ,- "' rrma b c d ell f,g

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11 ) (12)

i) 15 30 15 30 25 12 0.5 1.0 0.50

ii) 3 40 40 25 40 30 15 0.5 1.0 0.62

iii) 5 75 50 30 50 40 20 1.0 0.60

iv) 10 125 60 35 60 50 25 Select 1.0 0.58

v) 15 200 70 40 70 60 60 according 2 1.0 0.57

vi) 20 300 80 45 80 70 35 10 2 1.0 0.56

vii) 30 400 90 50 90 80 40 circumstances 2 1.0 0.56

viii) 40 790 110 65 110 85 50 2 1.0 0.59

ix) SO 1700 ISO 75 ISO 130 65 2 1.0 0.50

x) 75 4000 200 100 300 170 80 2 1.0 0.50

xi) 100 7000 250 110 250 220 100 2 1.0 0.44

Illfa scoopis alsousedforsampledivision, e - 0, thatis, the frontof thescoopiscutoff.

F IG. 1 A Scoop FOR INCREMENT SAMPLING

IS 15765: 2008

FIG. 2 A CONTAINER FOR INCREMENT SAMPLING

Table S Recommended Dimensions of Containen for Increment Sampling

(Clause A-2.2)

SI Appro:dmatr Dimensions, mm

No. Volume r A."'an' a b c

( I) (2) (3) (4) (5)

i) 75 50 50 30

ii) 125 60 60 35

iii) 200 70 70 40

iv) 300 80 80 45

v) 400 90 90 50

vi) 700 110 110 65

vii) 1700 150 150 75

viii) 4000 200 200 100

ix) 7000 250 250 120

7

IS 15765 : 2008

FIG. 3 E XAMPLES OF PROBES FOR INCREMENT SAMPLING

Table 6 Types of Rime Divider

(Clause A-2.5)

51 Nominal Top Size Number or Widtbor

No. inSample,d Divider Rimenun mrn

( I) (2) (3) (4)

i) 5< d < 10 20 20

ii) 2.4 <d < 5 10 10

iii) d <2 ,4 6 6

8

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