1405

IS : 1405 - 1982

Indian Standard METHODS OF SAMPLING IRON ORES

( Second Revision ) -

Methods of Sampling Sectional Committee, SMDC 4

Chaiman

DR DAROGA SINCJH

Rcprcstnting

Indian Agrkultural Statistics Rcscarch Institute, New Delhi

Mmbrrs

SHRI J. N. GARG ( Alternate to D? Daroga Sirigh)

SHRI S. N. AGARWAL Central Statistical Organization. New Delhi SHRI M. G. BHADE Tata Iron & Steel Co-Ltd, Jakhedpur

SHRI H. L. CHADHA ( Alternate ) DR M. M. CHAKRABORTY The Indian Iron & Steel Co Ltd, Bumpur SHRI A. W. CXAWATHE Government of India Mint ( Ministry of Finance ) SHRI S. K. DAS Directorate General of Supplies & Disponalr, N_ew

Delhi SARI B. DASGUPTA ( AIfrrnah )

SHRI B. K. DHRUVA RAO Mineral Exploration Corporation Ltd, Nagpur SHRI D. B. GHOSH Geological Survey of India, Calcutta SHRI C. N. HARMAN Ferro Alloys Corporation Ltd, Shreeramnagar

SHRI A. SANQAME~WARA RAO

SHRI $ PZE~)VAR SHEIK. P. PATEL ( Alfrmalu )

Italab Pvt Ltd, Bombay

SHRI P. K. KRISHNAMOORTEIY Ministry of Railways SHRI R. K. DASGUPTA ( Altcrnafr )

SHRI K. S. MAHAPATRA Indian Bureau of Mines, Nagpur SHRI U. N. SARKAR ( Alternate )

Smu A. K. MITRA Mitra S. K. Pvt Ltd, Calcutta SHRI M. N. MITRA ( Altarnate)

SHRX B. MIJKHERJEE Steel Authority of India Ltd, Bhilai SHRI P. K. PAIN National Test House, Calcutta SHRI R. J. PANDEY Indian Statistical Institute, Calcutta SHRI B. R. PATRL Therapeutics Chemical Research Corporation,

Bombay SHRI M. V. VAIDYA ( Altmatr )

SHRI T. R. PURI Army Statistical Organization (Ministry of Dcfence ), New Delhi

SHRI R. D. AQRAWAL ( Alkrnak )

@ Copyrighr 1982

INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under tbe said Act

IS :1405-1982

( Confinusdfrom pug.9 1 ) Members Represeniing

DR J. RAJARAM Esscn & Co, Bangalore SHRIV. SHANKARNARAYAN

(Alternate I ) SHRI K.N. GuRuRAJACHAR

(Alternate II ) DR M. RAN~A RAO Steel Authority of India Ltd, Ranchi ( R & D Orga-

nization ), Ranchi SHRI A. K. SATSANOI ( Alternate )

DR B. R. L. Row Hindustan Zinc Ltd, Udaipur SHRI G. L. JETHWANI ( Alternate )

SHRI P. M. SENGUPTA Directorate General of Inspection (Ministry of Defence )

SHRI T. K. BHA~ACHARJEE ( Alfernafe )

SHRI R. C. VIDYARTHI SHRI S. D. JHA (Alternate)

SHRI Y. K. BHAT, Director ( Stat)

Bharat Aluminium Co Ltd, New Delhi

Director General, ISI ( Ex-ojicio Member )

Secretury

SHRI N. SANKAR

Deputy Director ( Stat ), IS1

Subcommittee on Sampling of Ores, SMDC 4 : 3

Members

SHRI S. K. AQRAWAL Mine& & Metals Trading Corporation Ltd, New

DR S. M. RE~E ( Ahrnatc) SHRI D. N. BHARGAVA Indian Bureau of Mines, Nagpur

SHRI U. N. SARKAR ( Alternate ) SHRI S. K. DIKSHIT Indian Iron & Steel Co Ltd, Burnpur

SHRI A. GANCULY ( Alternate) DIRECTOR OF INDUSTRIES & MINCE Government of Goa, Daman & Dieu, Punjim, Goa SHRI N. B. GUDE Chowgule & Co Pvt Ltd, Mormugao, Goa SHRI C. N. HARMAN Ferro Alloys Corporation Ltd, Shreeramnagar

SHRI A. SANOAMESWARA RAO ( Alternate )

SHRI S. S. HONAVAR Italab Pvt Ltd, Bombay SHRI J. P. PATEL ( Alternate I ) SHRI J. C. DEY ( Alternate II )

DRSURESH M. JAMKHINDIKAR S. G. S. India Pvt Ltd, Bombay SHRI D. LAHIRI Geological Survey of India, Calcutta SHRI G. P. MATHUR National Metallurgical Laboratory ( CSIR ),

SHRI A. K. MITRA Jamshedpur

Mitra S. K. Pvt Ltd, Calcutta SHRI M. N. MITRA ( Altcrnafe)

SHRI M. M. MOUDGILL Indian Aluminium Co Ltd, Calcutta SHRI B. MUKHERJEE Bhilai Ispat Ltd, Bhilai

SHRI PIJV~H KANTI BANERJEE (Alternate )

2

( Continued on page 17 )

IS :1405 -1982

Indian Standard METHODS OF SAMPLING IRON ORES

( Second Revision )

0. FOREWORD

0.1 This Indian Standard ( Second Revision ) was adopted by the Indian Standards Institution on 25 June 1982, after the draft finalized by the Methods of Sampling Sectional Committee had been approved by the Structural and Metals Division Council.

0.2 This standard was originally issued in 1961 and it was subsequently revised in 1966. Since then, a lot of developments have taken place in iron ore industry and trade. With the increased capacity of ships, the tonnage of a single consignment of export from Indian ports has crossed the one lakh mark. Further handling operations have become faster thereby necessitating speed in the operations of sampling, sample preparation, . analysis and final estimation of quality of iron ore consignments.

0.3 In the present revision, lot sizes beyond one lakh tonnes have also been covered and the number of sub-lots into which a lot is to be divided has been slightly reduced taking into account the need for faster sampling operations. Delivery of iron ore in trucks has been quite popular in some parts of the country and to cater to this situation sampling from trucks has also been introduced in the present revision.

0.4 Taking into consideration the latest developments in iron ore industry and trade at national and international levels, the classification of iron ore has been changed to include four categories, namely, lump, sized ore, calibrated ore and fines.

0.5 The present revision mainly deals with manual sampling of iron ores and as such cannot be employed in those cases where sampling and sample preparation are fully mechanised.

0.6 In the formulation of this standard due consideration has been given to international coordination among the standards and practices prevail- ing in different countries. For this purpose, reference has been made to the following documents issued by International Organization for Standardization:

i) ISO/TC 102/SC 1 N 529E - Draft Proposal ISO/DP 3081- Iron Ores - Increment Sampling - Manual Method.

ii) ISO/TC 102/SC 1 N 530E - Draft Proposal ISO/DP 3083 Iron Ores - Preparation of Samples - Manual Method.

3

IS :1405-1982

0.7 For the determination of size distribution of iron ores, sieves conform- ing to IS : 460 ( Part I)-1978* and IS : 460 ( Part II )-1978t, shall be used. When such sieves are not available other equivalent standard sieves as judged by the aperture size may be used.

0.8 In reporting the result of a test or analysis made in accordance with this standard, if the final value observed or calculated is to be rounded off, it shall be done in accordance with IS : 2-19601.

1. SCOPE

1.1 This standard prescribes the methods for sampling of iron ores from conveyors, wagons, trucks, ships and stock piles for the determination of size distribution, moisture content and chemical composition of the ore in the lot. It also lays down a method for reporting the quality of the material sampled.

2. TERMINOLOGY

2.0 For the purpose of this standard, the following definitions shall apply.

2.1 Lump - Ores consisting of all sizes up to 150 mm.

2.2 Sized Ore -Ores of sizes greater than 10 mm but not exceeding 100 mm.

2.3 Calibrated Ores - Ores of sizes greater than 10 mm but not exceeding 35 mm; also of sizes greater than 6 mm but not exceeding 30 mm.

2.4 Fines - Ores of sizes not exceeding 10 mm.

2.5 Lot - The quantity of ore indicated to be of the same category ( see 2.1 to 2.4) and offered for inspection at one time. A lot may consist of the whole or a part of the quantity ordered for.

2.6 Sub-lot - The quantity of ore in each of the parts into which a lot is divided for the purpose of sampling.

2.7 Increment - The quantity of ore obtained by a sampling device. at one time from a lot or sub-lot.

2.8 Unit Sample - The quantity of ore collected at one point in sectional sampling or at one time from the conveyor by stopped belt method.

*Specification for test sieves: Part I Wire cloth test sieves ( second revision ).

tSpecification for test sieves: Part II Perforated plate test sieves (second revision).

$Rules for rounding off numerical values.

4

IS : 1405 - 1982

2.9 Gross Sample- Sample as collected from a sub-lot, that is, the quantity of ore consisting of one or several increments or unit samples taken from a sub-lot.

2.10 Size Sample -The sample taken for the determination of the size distribution of the lot or sub-lot.

2.11 Laboratory Sample ( Sub-lot ) -The quantity of ore obtained by reducing a gross sample following a specified procedure and intended for laboratory testing.

2.12 Moisture Sample - The sample to be used exclusively for the purpose of determining moisture content.

2.13 Composite Sample for the Lot - The quantity of ore obtained by mixing together equal quantities of ores from each of the sub-lot laboratory samples. When sub-lots vary considerably in mass, quantities of laboratory samples proportionate to the weight of the sub-lot may be taken and mixed.

NOTE -Whenever preparation of sub-lot laboratory samples is not required, the composite sample for the lot can be prepared by mixing gross samples at - 10 mm stage in proportion to the sub-lot tonnages.

3. .GENERAL PROCEDURE FOR SAMPLING

3.1 Sub-lots - For the purpose of sampling, a lot shall be divided into a number of sub-lots of approximately equal mass as specified in Table 1.

NOTE -When it is not practicable to have sub-lots of approximately equal mass, sub-lots with varying mass may also be permitted.

TABLE 1 NUMBER OF SUB-LOTS INTO WHICH A LOT IS TO BE DIVIDED

(C~auses3.1,4.2,5.1,6.1,7.1 and8.1)

Miss OF THE LOT MINIMUM N-RR (in tonnes ) SUB-LOTS

up to 5 000 2 5 001 ,, 10 000 3

10 001 )) 15 000 4

15 001 ,) 25 000 5

25 001 ,, 35 000 6

35 001 ,, 45 000 7

45 001 ,, 60 000 8

60 001 ,, 75 000 10

75 001 ), 100 000 12

100 001 ,, 130 000 14

130 001 160 000 16

160 001 adb above 18

OF

IS : 1405 - 1982

3.1.1 A representative gross sample shall be drawn from each of the sub- lots and shall be kept separately. Thus, there will be as many gross samples as the number of sub-lots into which the lot has been divided.

3.2 Minimum Mass and Number of Increments - The number of increments to be taken from a sub-lot for drawing the gross sample shall be governed by the mass of the gross sample and the mass of increments as specified in Table 2 for various categories of ores. This number shall be evenly distri- buted over the sub-lot. The increments shall be drawn with the help of a suitable sampling scoop (see Fig. 1 ) at regular intervals.

TABLE 2 MINIMUM MASS OF THE GROSS SAMPLE AND MINIMUM NUMBER OF INCREMENTS

( Clauses 3.2, 4.2, 5.2.1, 6.2, 7.2, 8.2.1 and 8.3.2 )

LUMP SIZED CALIBRATED FINES

Mass of gross sample in kg ( Min ) 800 600 400 200 Mass of increment in kg ( Approx ) 8 8 4 4

No. of increment ( &fin ) 100 75 100 50

4. SAMPLING FROM CONVEYORS BY STOPPED BELT METHOD

4.1 When iron ore is moved on conveyors, one of the most reliable methods of manual sampling is stopped belt method. Whenever it is practicable to stop the conveyor belt periodically, a Iarge quantity of iron ores known as unit sample may be drawn by stopping the belt. The mass of different unit samples shall not be less than 100 kg and shall be collected from the full width and thickness of the ores stream over a suitable length of the conveyor. The number of unit samples to be drawn at regular interval to constitute a gross sample shall be as given below for different categories of iron ores:

Category Minimum Number of Unit Samples for Sampling from Conveyors

for Each Sub-lot Lump 8 Sized 6 Calibrated 4 Fines 2

4.2 In case it is not possible to stop the conveyor, increments as per Table 2 shall be collected at regular intervals at a suitable transfer point in the conveyor system.

4.3 The material collected as unit samples or increments in a sub-lot shall be aggregated and mixed together to constitute a gross sample.

,

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1s : 1405 - 1982

5. SAMPLING DURING LOADING OR UNLOADING OF WAGONS

5.1 Sub-iots - For the purpose of sampling, all the wagons in a lot shall be divided into a suitable number of sub-lots of approximately equal mass in accordance with the requirements of Table 1.

5.1.1 A representative gross sample shall be drawn from each of the sub- lots and shall be kept separately. Thus, there will be as many gross samples as the number of sub-lots into which a lot has been divided.

5.2 In order to get a representative gross sample, the ore shall be sampled as far as possible in a steady motion during loading or unloading of the wagons.

5.2.1 A minimum of 25 percent of the wagons shall be selected at random from the sub-lot. The number of increments to be taken from the selected wagons and the mass of the increments and the gross sample shall be in accordance with Table 2. The increments shall be evenly distributed over the selected wagons with a view to determining the necessary number of increments that should be collected from each of the wagons of the sub-lot for making up the gross sample. These increments shall be drawn with the help of a suitable scoop (see Fig. 1 ) at regular intervals at the time of loading or unloading of the wagons.

NOTE -While taking the increments as described above, if a large lump is encoun- tered at any point and cannot be taken in the scoop, it shall be picked up as such. The lump so obtained shall, however, be accounted for in the determination of the ore size distribution as given under 9 and in the reduction of gross samples as given under 10.

6. SAMPLING DURING LOADING OR UNLOADING OF TRUCKS

6.1 Sub-lot - Quite often the nature of iron ore tendered in trucks is as heterogeneous as that supplied in wagons or ships and variation in terms of particle size and chemical composition has been found to be considerable which requires limiting of sub-lot tonnage. Hence, when iron ore is sup- plied in trucks the sub-lot size shall not exceed 100 trucks counted on continuous basis. If loading or unloading is done shift-wise, sub-lots may be conveniently formed in terms of trucks handled in one shift, subject to the condition that the size of each sub-lot shall not exceed 100 trucks.

Hundred percent of the trucks are to be sampled if the ores originate from more than one source and minimum 25 percent of the trucks in the sub-lot are to be sampled if the ore is from a single source. The number of increments per truck shall be adjusted SO that total number of increments from each sub-lot ( 100 trucks or less ) is always greater than or equal to the number specified in Table 2 for various categories of ores.

6.2 In order to get representative sample, increments shall be drawn at the time of loading or unloading of the trucks. From each truck in the sub-lot,

7

Is : 1405 - 198a

a minimum of one increment shall be drawn. For drawing increments 8 kg or 4 kg sampling scoop ( Fig. 1) shall be used depending on the category of ore. At the time of taking increments care shall be taken not to exclude deliberately lumps or fines and this will be ensured by drawing increments in the middle of loading/unloading time of a truck.

6.3 The aggregate of increments collected from each sub-lot shall constitute a gross sample.

7. SAMPLING FROM SHIPS DURING LOADING/UNLOADING

7.1 For the purpose of sampling the quantity of ore to be loaded into or unloaded from ship shall be divided into a suitable number of sub-lots of approximately equal mass in accordance with Table 1.

7.1.1 A representative gross sample shall be drawn from each of the sub- lots and shall be kept separately. Thus, there will be as many gross samples as the number of sub-lots into which a lot has been divided.

7.2 In order to get a representative gross sample, ore shall be sampled as far as possible when in motion. If it is taken on a conveyor, the gross sample shall be collected according to the procedure laid down in 4. If the ore is handled in any other manner the gross samples may be drawn during loading or unloading of the ship. For this purpose, the number of increments to be taken at regular intervals and the mass of the increments and the gross sample shall be in accordance with Table 2 for different categories of ore ( see also Note under 5.2.1).

7.3 The aggregate of the material collected from the various increments or unit samples from a sub-lot shall constitute a gross sample.

8. SAMPLING FROM STOCKPILES

8.1 Sub-Lots - For the purpose of sampling, the quantity of iron ore in a stockpile shall be divided into a suitable number of sub-lots of apprqxi- mately equal mass as specified in Table 1.

8.1.1 A representative gross sample shall be drawn from each of the sub- lots and shall be kept separately. Thus, there will be as many gross samples as the number of sub-lots into which the lot has been divided.

8.a Sampling of ore from stockpiles shall be carried out, as far as possible, when ore is in motion, that is, during the making or breaking of the stockpiles.

8.a.l The number of increments to be taken from a sub-lot for making up the gross sample, shall be governed by the mass of the gross sample and the mass of the increments as specified in Table 2 for various categories of iron ore. This number shall be equally distributed over the sub-lot. The

9

IS : 1405 - 1982

increment shall be drawn with the help of a suitable sampling scoop ( see Fig. 1) at regular intervals in the course of making or unmaking of the stockpiles (see also Note under 5.21).

8.3 When it becomes necessary to sample a stationary stockpile sectional sampling method ( see 8.3.1) or trench sampling method (see 8.3.2 ) may be used for a stockpiles up to a maximum height l-5 metre only. In the former case, the requisite number of points shall be located at random on the entire surface of the sub-lots.

8.3.1 Sectional Sampling - By this method, at least 4 unit samples in the case of fine and calibrated ores and at least 8 unit samples in the case of sized ore and lumps are to be collected from each sub-lot. For this pur- pose, the requisite number of points shall be chosen at random on the entire surface of the stockpiles. At each of the selected points, a circle of suit- able diameter (minimum three times the largest particle size ) shall be marked. The material over the area of this circle and along entire height of the stockpile from top to bottom shall be collected in stages. This can be done by taking initially ores up to a depth of 50 cm and covering the hole so formed by a plate for removing the ores lying on the sides of the hole. Then after removing the plate further depth can be reached in the same manner and the ores can be collected from the freshly formed hole.

8.3.2 Trench Sampling -The gross sample shall be made up of the number of increments as specified in Table 2. These increments shall be collected as indicated in 8.3.2.1.

8.3.2.1 Along a randomly chosen line on the ore surface of the sub-lot, a trench shall be dug, right down to the ground level leaving about O-3 m walking space at the ground level. From the trenches so dug, the required number of increment shall be collected with the help of suitable sampling scoop, at various points randomly spread over the two exposed sides of the trenches. In case of large stockpiles, in addition to the trench, the sides of the piles may also be opened to expose the ore down to the bottom, at places where the trench does not expose the ore inside.

9. DETERMINATION OF SIZE DISTRIBUTION

9.1 The size distribution of iron ores in a lot shall be estimated as per contract. In the determination of ore size distribution, IS sieves of suitable sizes specified in IS : 460 ( Part I )* and IS : 460 ( Part II)? shall be used.

9.2 Gross Samples Obtained from Aggregating Unit Samples

9.2.1 Each gross sample shall be screened through selected IS sieves and the ore retained on each of the sieves and that passing through the

*Specihation for test sieves: Part 1 wire ~10th te!+t sieves ( second rmision ). tSpecification for test sieves: Part II Perforated test sieves ( second rtvision ).

10

IS : 1405 - 1982

smallest sieve shall be weighed separately. Ore size distribution of the lot shall be estimated as follows:

Percentage mass in the size range A = a, + as + -*-.** x. 100 Wl + wg + . . . . . .

where

WI, w2, . . . . . . are the mass of the different gross samples; and a,, a2 . . . . . ., are the corresponding masses of ore in the size

range A ( A may be below, above or bounded by two nominal sizes of IS sieves ).

9.3 Gross Samples Obtained by Aggregating Increments

9.3.1 Where gross samples do not contain any lumps, the procedure detailed in 9.2 shall be followed for estimating the ore size distribution in the lot, the percentage of ore. over 150 mm being nil.

9.3.2 Where the gross samples contain some lumps (see Note under 5.2.1) the portion of the gross samples excluding the lumps shall be treated as in 9.2.1.

9.3.2.1 The ore size distribution of the lot shall be estimated as follows:

a) Over 150 mm, percent = nx8 (n x 8) i- ~1 + w2 + wQ + . . . . . .

b, + b, + . . . . . . ._I . . . b) Any other size fraction B = -

(n x 8 ) + w, + w, + We . . . . . .

where w* WI . . . . . . are the mass of the different gross sample

excluding the lumps, n is the total number of lumps in all the gross samples, and bl, b, . . . . . . are the mass of ores in the size range B in different

gross samples.

NOTF -For lump and sized ores, each lump picked up in the course of sampling is supposed to represent one increment of 8 kg.

10. REDUCTION OF GROSS SAMPLE

10.1 Each of the gross samples if preserved in tin containers ( with suitable lid) shall be sent first for size distribution and only after that sample pre- paration shall be conducted. The stages of reducing a gross sample from each sub-lot to moisture sample as well as chemical analysis sample are

11

IS : 1405 - 1982

shown in Fig. 2. The preparation of final moisture samples in duplicate of 1 kg each, may be preferably carried out by increment reduction method.

NOTE 1 -When the gross samples are not preserved in tin containers or when it is agreed to between the purchaser and supplier,.separate moisture sample may be drawn from each sub-lot by collecting a separate addlrional increment for every 10 increments. These additional increments shall be combined together for each sub-lot and be kept in air-tight containers with full details of sampling, before they are sent for moisture determination.

NOTE 2 - The stage 3.35 mm could be eliminated in the case of calibrated and fine ores.

Gross Sample +

Size determination

Crushed tt - 10 mm 4

Mixing and reduction to 50 kg 4

J- 25 kg of reduced sample

4

J 25 kg reduced sample

Crushed to pass through 475 mm IS Sieve 4

4 Duplicate moisture

Mixing and reduction to 12.5 kg samples of 1 kg each by increment reduction

+ Crushed to pass through 335 mm IS Sieve

Mixing and reductionto 6.2 kg 4

Crushed to pass through 1.70 mm IS Sieve J-

Mixing and reduction to 3.1 kg 4

CrUISSheSd;;;epass through 850 micron

Mixing and reduction!to 1.6 kg

Pulverized to pass thrtugh 150 micron IS Sieve

( Laboratory sample for chemical analysis )

FIG. 2 STAGES IN REDUCING A GROSS SAMPLE

10.2 Preparation of Samples for Moisture and Chemical Analysis - Each gross sample shall be reduced separately. Ores of sizes greater than 10 mm in the gross sample shall be first crushed in jaw crusher, roll crusher or by manual labour using a hammer, pounder and a manganese steel plate till the ore in the gross sample is of size - 10 mm. This shall be mixed well and reduced to 2 parts of 25 kg each. This shall then be further processed in stages as detailed in Fig. 2 to prepare the laboratory samples for moisture and chemical analysis. For reduction at various stages one of the

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IS : 1405 i 1982

methods detailed in 10.2.1 to 10.2.3 shall be followed. Each of the moisture samples shall weigh minimum 1 kg and laboratory sample minimum 150 g.

10.2.1 Reduction by R@e Divider - After each crushing the ore shall be well mixed and poured into the riffle. This process shall be repeated using different sizes of riffles according to the size of the crushed ore.

10.2.2 Coning and Quartering Method- The crushed ore shall be well mixed and then scooped into a cone-shaped pile. Care shall be taken to drop each scoopful exactly over the same spot as otherwise the central axis of the cone will be slackened and an uneven distribution of lumps and fines will result. After the cone is formed, it shall be flattened by pressing the top of the cone with the smooth surface of the scoop. Then it is cut into quarters by two lines which interesect at right angles at the centre of the cone. The bulk of the sample is reduced by rejecting any two diagonally opposite quarters.

10.2.3 Increment Reduction Method -The crushed ore shall be spread on a smooth non-moisture absorbing plate into a uniform flat rectangle with the thickness specified in Table 3. The rectangle so formed shall be divided into 5 equal parts lengthwise and 4 equal parts breadthwise. From each of the 20 parts so obtained, equal quantities of ore shall be collected by the use of suitable scoop once or more number of times depending on the quantity of divided sample.

10.2.3.1 The method of increment reduction is recommended only when the division ratio is high. As such, in the illustration given in Fig. 2, this method can be applied in the initial stage when the gross sample is reduced to 50 kg, and also at the final stage for obtaining laboratory samples. For obtaining duplicate moisture sample also, increment reduc- tion method is preferred to other methods. Table 3 gives the thickness of layer of ores and the minimum mass of increment from each rectangular part, to be taken at one time with the use of suitable sampling scoop.

10.3 Laboratory Samples - The laboratory samples shall be obtained after the material is pulverized to pass through 150-micron IS Sieve. The material so obtained shall be divided into three or more equal parts, as requested by the purchaser, the supplier, the referee and others, if any. All the laboratory samples shall be preserved in dry, clean and well stoppered containers and labelled with full identification particulars like, source of the ore, category of the ore, suppliers name, the lot and sub-lot number and date of sampling.

11. NUMBER OF TESTS

11.1 Moisture Sample- All the moisture samples representing a lot shall be tested individually for moisture content. Duplicate moisture

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ls : 1405 - 1982

TABLE 3 THICKNESS OF THE LAYERS AND QUAXVMTIES TO BE COLLECTED FROM EACH PART

( Clause 10.2.3.1 )

MAXIMUM SIZE OF ORE

(1) mm

10 4-75 3.35 l-70 O-85 o-15

THICKNESS OF LAYER

(2) mm

30 to 40 25 to 35 20 to 30 15 to 25 10 to 20 5 to 10

APPROXIMATE QUANTITY TO BE OBTAINED PROY EACH

PART AT Om TIME

(3)

S 250 150

z 25 5

determinations shall be made for each sub-lot. To avoid any change in the moisture content, the moisture determination shall be done as quickly as possible, after the sample is taken.

11.2 Sub-lot Laboratory Samples - All the sub-lot laboratory samples shall be tested individually for important chemical characteristics. For testing the remaining characteristics, a composite sample as prescribed in 2.13 shall be prepared and analysed. The following scheme is recommended for carrying out chemical tests of iron ore:

Chemical Constituents of the Ore for Which

Sub-lot samples are analysed A composite sample is individually analysed

Fe content and any other All the radicals chemical characteristic which is in the contract important or found variable

stipulated

12. REPORTING

12.1 Reporting of Chemical Composition

12.1.1 For those characteristics, where a composite sample has been tested, only one test result will be available and that result shall be reported as the value of the characteristic for the lot sampled.

12.1.2 When only two laboratory samples have been analysed individually from a lot, the average of the two available test results shall be reported as the value of the characteristic for the lot sampled. In the case of sub-lots of approximately equal mass, this average shall be calculated as one half of the sum of the two test results. If the sub-lots are of varying mass, then the weighed average shall be calculated as the sum of each test result multiplied by corresponding fraction got on dividing the sub-lot weight by

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IS : 1405 - 1982

the total weight. The individual results shall also be reported to given an indication of the range of variation in quality.

12.1.3 When three or more laboratory samples have been analysed individually from a lot for any characteristic, the following procedure shall be followed to assess the average quality and its limits of variation:

Let x1, x2, x8... . . . . . . . . . . . . . . . xn be the results of analysing n laboratory . samples for a particular characteristic.

Calculate: . . . . . . . . . . . .

Average(z)= X1+ n Xn if sub-lots are of approximately equal weight

or Weighted

average ( K ) = wrxr + . . . . . . . . . wnxn WI + ---*-****-****- WI1

where wl, IV*, . . . . . . . . . w,, are mass of the sub-lots.

Range ( R) = the difference between the maximum and the minimum of the values ( when n is less than 10 )

or ( x) = the average value of ranges. When the number of sub-lots n is equal to 10 or more, the corresponding results on laboratory samples ( 10 or more) should be constituted into two groups in the order of their occurrence. For each group, range ( R ) should be calculated and the average value ( K) of the Rs should be used in the subsequent clause.

The average level of the characteristic in the lot shall be reported as equal to (z).

The limits of variation in the average level of the lot shall be reported as (I? f hR) or ( P f hE), where h is a factor, the value of which depends on the number of samples analysed. The appropriate value of the factor h shall be taken from the following table:

No. of Laboratory Value of the Samples AnaIysed Factor h

3 I.30 4 O-72

z o-51 o-40

7 0.33

1: 0.29 o-31

12 0.25 14 o-21

ii o-19 0.17

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IS :1405-1982

12.2 Reporting of Moisture Content - The result obtained from the sub-lot shall be denoted by xi. In case duplicate test results are obtained from its sub-lot, average of these two results shall be denoted by xi. The average moisture content of iron ore in a lot shall be calculated as follows:

where

Average moisture content = I; mixi Zm 1

rni is the mass of the ith sub-lot. I: stands for summation over all 9s.

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Is :1405-198t

( fhtinwd from page 23

Mmb#rs Rtprwntinp

SBRI R. C. PALHAN Export Inspection Council of India, Calcutta SHRI KARAM CHAND (Alternate)

SHRX B. R. PATEL Therapeutics Bombay

Chemical Research Corporation,

Snar M. V. VA~DYA ( Al&mate) DRJ.RAJARAM Essen & Co Bangalore

SHRlK.N.GIJRURAJACHAR _ ( Altcmak )

SHRI M. R. ROY

SHRIG.V. SUEIRAMAHYA~

SHRI V. P. ROY ( Altcma& ) SRRI G. R. TALAULIKAR

Inspe;$~;~t~Br Testing Co ( India) Pvt Ltd,

National Mineral Develop*ment Corporation Ltd, Hyderabad

Goa ( gEaral Ore Exporters Association, Panjim

17

Title Page0. Foreword1. Scope2. Terminology3. General Procedure for SamplingTable 1Table 2

4. Sampling from Conveyors by Stopped Belt Method5. Sampling During Loading or Unloading of Wagons6. Sampling During Loading or Unloading of TrucksFig. 1

7. Sampling from Ships During Loading/Unloading8. Sampling from Stockpiles9. Determination of Size Distribution10. Reduction of Gross SampleFig. 2

11. Number of TestsTable 3

12. Reporting

s: (Reaffirmed 2003)