M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m-w@m-w.dk | Web: www.m-w.dk

M&W JAWO HANDLING

RSS – REPRESENTATIVE SAMPLING SYSTEM REPRESENTATIVE SAMPLING (BULK MATERIAL)

� The sampling system operates in

accordance with approved international standards.

� Final sample size is suitable for making laboratory analysis.

M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m-w@m-w.dk | Web: www.m-w.dk

M&W JAWO HANDLING

INTRODUCTION

The basic purpose of sampling is to collect a manageable mass

of material which is representative of the total mass of material

from which it was collected. This manageable mass of material,

called a “sample”, is subject to certain preparation procedures,

which render it suitable for either physical testing, or

laboratory analysis. The types of tests or analyses, which are

performed, are dependent on what characteristics are required

to be measured to categorise the material.

The method by which samples are collected, the frequency of

collecting samples and the accuracy of the samples collected,

that is, how closely they represent the true characteristics of

the total mass, all depend on the nature of the material being

sampled. A totally homogeneous material will require the

collection of only a single sample in order to determine its

characteristics accurately, whereas a lumpy heterogeneous

material will require the collection of many small samples, or

increments, which, when combined, will represent the total

mass, or lot, with an acceptable degree of accuracy. These

increments should be collected from all parts of the lot, with

the number required to be collected being dependent on the

variability of the material constituting the lot.

Since it is required to collect increments from all parts of the

lot, it is necessary that the total lot is accessible. In other

words, it is of fundamental importance that all particles in the

lot have the same probability of being included in the final

sample. To achieve this requirement, it is desirable to sample

the lot whilst it is in a dynamic state.

GENERAL DESCRIPTION

Knowledge of the bulk material properties:

• Content of prime property

• Moisture content

• Content of contamination

• Hardness (Hard Grove Index)

• Size distribution

• And many other properties

are essential when controlling the quality of the material.

The properties are identified by taking representative samples

from each bulk material batch used or collected.

The Representative Sampling provides the operator with the

means for executing the extraction and preparation of

representative samples of the material.

The Representative Sampling System operates in accordance

with approved international standards.

The sample size is suitable for making laboratory analysis.

The results of the laboratory tests performed on the basis of the

representative samples prepared by the sampling system is

used for:

• Calculating the value or payment for each batch of material

• Adjusting downstream production

• Calculating the amount of by-products from each batch

• Calculating the blending of various material batches

M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m-w@m-w.dk | Web: www.m-w.dk

M&W JAWO HANDLING

EXAMPLE OF SAMPLING PLAN (COAL)

In order to verify the coal properties for a given coal lot it is

necessary to take out a number u of sampling units. This

number depends on the mass of the lot and on the desired

overall sampling precision. Minimum requirements are listed in

Table 1.

Each sampling unit is taken by the sampling equipment as n

increments, where n should be 10 or more.

The properties of the coal lot can be determined with an overall

precision PL using equation 1 where:

• VPT is variance of sample preparation and test. If no data • available: Assume 0.2 • VI is the variance of primary increment. If no data

available: Assume 20

The overall precision is a function of the number of sampling

units u, the variance of sample preparation and test VPT, the

number of increments n and the variance of the increments VI.

If a given precision PL is required the number of increments n

and the number of sampling units u can be found using

Equation 2 and 3 respectively.

The values n and u are adjusted upwards and recalculated to a

convenient combination respecting the required minimum

values.

Equation 1: �� = ±2

��

��

�

Equation 2: � = ���

��������

Equation 3: � = ��������

�����

EQUIPMENT SIZING CONSIDERATIONS

The mass of each primary increment can be calculated using

Equation 4 where:

• C is flow rate [t/h] on conveyor belt. • A is cutting aperture [mm].

Should be ≥ 3 times the nominal top size of coal. • S is cutter speed [m/s].

If S is constant the incremental mass is a function of the flow

rate C, the nominal top size of the coal lumps and cutting

aperture A.

As a guideline for lay-out of sampling systems the reference

increment mass from Table 2 should be used as minimum

values.

The total mass of the sample (sampling unit) is at least n times

the increment mass where n is at least 10 as previously

discussed.

Sample division

To obtain convenient sample masses, the sample is divided into

a number of statistically identical but smaller samples and a

rest which is returned to the coal conveyor.

From the preceding section is seen, that reducing the mass

needs a reduction in particle size in order to preserve the

representative nature of the sample. For this reason a system

for extraction of representative samples of coal consists of

multistage extraction, particle reduction and division

equipment.

Equation 4: � = �∙�

�,�∙� ∙ 10��[#$]

Mass of Lot tonnes No. of sampling units < 5.000 1

5.001 - 20.000 2 20.001 - 45.000 3 45.001 - 80.000 4 80.001 - 125.000 5

125.001 - 180.000 6 180.001 - 245.000 7

Nominal top size of coal [mm] Reference incr. mass [kg] 300 100 200 25 150 15 125 10 90 5 63 3 45 2 31,5 1 22,4 0,75 16 0,50 11,2 0,25 8 0,15

M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m-w@m-w.dk | Web: www.m-w.dk

M&W JAWO HANDLING

TYPICAL PROCESS DIAGRAM

1. Main conveyor belt

2. Cross Belt Bucket Sampler (CBBS)

3. Dosing Conveyor (DC)

4. Twin Roll Crusher (VK)

5. Rotary Tube Divider (PD)

6. Bias Valve

7. Buffer Container

8. Dosing Conveyor (DC)

9. Rotary Tube Divider (PD)

10. Sample Containers

11. Reject Conveyor (RC)

DEFINITIONS

Lot: A quantity of material for which the overall quality to a particular precision needs to be determined.

Sub-lot:

Equally sized parts of a lot, which properties are to be determined. Norminal top size: The smallest sieve on which not more than 5% of the sample is retained. Primary Increment:

The amount of material which the primary sampling tool takes out of the material stream in one cut. Cut: An increment taken by a sampler. Gross Sample:

A material sample consisting of all the primary Increments taken from a sub-lot. Division: A sample preparation process, in which the sample is divided in a number of smaller portions. Sample:

The quantity of material consisting of all the increments taken from a lot/sub-lot. Final sample:

A sample prepared from the sample of a sub-lot. Precision:

Expressed in % and within 95% confidence level. Bias:

A systematic error that creates results that on regular basis are higher or lower than the true value.

M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m-w@m-w.dk | Web: www.m-w.dk

M&W JAWO HANDLING

QUESTIONNAIRE FOR SAMPLING AND SAMPLE PREPARATION

Plant name, owner and address E-mail, ID and phone no.

Media (material type)

Reference standard

Location of sample extraction (free fall at belt end or on the belt)

Place for disposal of reject material

Weight of total LOT t

Period of time for LOT h

Bulk density of material kg/m³

Max. grain size Nominal top size

mm

Conveyor belt

width mm

speed m/sec

capacity t/h

height above ground m

After sample preparation:

Final max. grain size mm

Final sample weight kg

EXAMPLE OF COMPLETED QUESTIONNAIRE

Media (material type) Coal

Reference standard ISO 13909

Location of sample extraction (free fall at belt end or on the belt)

On the horizontal belt

Place for disposal of reject material Back on the main horizontal belt

Weight of total LOT 20000 t

Period of time for LOT 8 h

Bulk density of material 2200 kg/m³

Max. grain size Nominal top size

50 30

mm

Conveyor belt

width 1200 mm

speed 1,6 m/sec

capacity 2500 t/h

height above ground 5 m

After sample preparation:

Final max. grain size 10 mm

Final sample weight 10 kg

M&W JAWO HANDLING A/S | Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E

M&W JAWO HANDLING

Rotary Tube Divider (motorised flap)

Cross Belt Hammer Sampler

| Oldenvej 5 | 3490 Kvistgaard | Denmark | Phone: +45 49139822 | E-mail: m

ed flap) Sampl

Cross Belt Hammer Sampler Twin Roll Crusher

M&W JAWO HANDLING is an internationally

working engineering company specialised in

design, manufacturing and supply of individual

machine units and systems for

sampling of powder and bulk material.

Several hundred systems are successfully

sampling in the industry world

mail: m-w@m-w.dk | Web: www.m-w.dk

Sample Collector

Twin Roll Crusher

M&W JAWO HANDLING is an internationally

working engineering company specialised in

design, manufacturing and supply of individual

machine units and systems for representative

sampling of powder and bulk material.

Several hundred systems are successfully

sampling in the industry world-wide.