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GB/T 6949-2010 English PDF (GBT6949-2010)

GB/T 6949-2010 English PDF (GBT6949-2010)

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GB/T 6949-2010: Determination of apparent relative density of coal
GB/T 6949-2010
GB
ICS 73.040
D 21
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 6949-1998
Determination of
apparent relative density of coal
ISSUED ON. JANUARY 10, 2011
IMPLEMENTED ON. JUNE 01, 2011
Issued by. General Administration of Quality Supervision, Inspection
and Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1  Scope ... 4 
2  Normative references ... 4 
3  Terms and definitions ... 4 
4  Method summary ... 5 
5  Reagents ... 5 
6  Instruments and equipment ... 5 
7  Coal sample collection and preparation ... 6 
8  Determination procedures ... 7 
9  Calculation results and expression ... 8 
10  Precision of method ... 9 
Annex A (Normative) Empirical Formula of Calculating Apparent Relative
Density ... 10 
Based on True Relative Density ... 10 
Annex B (Normative) Determination of Paraffin Wax Density ... 11 
Foreword
This Standard replaces GB/T 6949-1998 Determination of apparent relative density of coal.
Compared with GB/T 6949-1998, main changes of this Standard are as follows.
— Modify Annex B. Use “10 Determination methods for lignite wax” of GB/T 2559-2005
Analysis of lignite wax to replace the Annex B of previous standard.
Annex A and Annex B of this Standard are normative.
This Standard was proposed by China National Coal Association.
This Standard shall be under the jurisdiction of National Technical Committee on Coal of
Standardization Administration of China.
The responsible drafting organization of this Standard. Xi’an Research Centre of China
Coal Science Research Institute.
The chief drafting staffs of this Standard. Wang Jieling, Long Yaping, and Zhu Chunsheng.
This Standard replaces the following historical editions.
— GB 6949-1986, GB/T 6949-1998.
Determination of Apparent Relative Density of Coal
1 Scope
This Standard specifies the instruments and equipment, reagents, coal sample preparation,
determination procedures, results calculation, and degree of precision for determination of
apparent relative density of coal.
This Standard applies to lignite, bituminous coal and anthracite.
2 Normative references
The articles contained in the following documents have become part of this Standard when
they are quoted herein. For the dated documents so quoted, all the modifications
(excluding corrections) or revisions made thereafter shall not be applicable to this Standard.
For the undated documents so quoted, the latest editions shall be applicable to this
Standard.
GB 474 Method for preparation of coal sample (GB 474-2008, ISO 18283. 2006, Hard
coal and coke - Manual sampling, MOD)
GB 475 Method for manual sampling of commercial coal (GB 475-2008, ISO 18283.
2006, Hard coal and coke - Manual sampling, MOD)
GB/T 482 Sampling of coal seams
GB/T 19494.1 Mechanical sampling of coal - Part 1. Method for sampling (GB/T
19491.1-2004, ISO 13909-1. 2001 Hard coal and coke - Mechanical sampling - Part 1.
General introduction, ISO 13909-2. 2001, Hard coal and coke - Mechanical sampling -
Part 2. Coal - Sampling from moving streams, ISO 13909-3. 2001, Hard coal and coke
- Mechanical sampling - Part 3. Coal - Sampling from stationary lots, NEQ)
Specification of coal resources exploration and coal sampling 1989
3 Terms and definitions
For the purpose of this Standard, the following terms and definitions apply.
3.1
Apparent relative density of coal
the provisions of “Regulations on Collection of Coal Resources Exploration and Sampling”.
Then crush to particles of which the size is less than 13 mm through step-by-step crushing
method according to GB 474; separate one half of coal samples; use 10mm round-hole
sieve (6.8) to screen out the coal sample with (13~10)mm particle size, and make it reach
a air dry state. Put into coal sample bottle to serve as the coal sample for determination of
apparent relative density.
8 Determination procedures
8.1 Pave the coal particles from coal sample bottle onto plastic cloth (6.9); use
checkerboard method to take out (20~30)g of coal samples; for the coal of which the ash
content is greater than 30% or total sulfur is greater than 2%, weigh (40~60)g; place onto
1 mm square-hole sieve (6.8); use hair brush to repeatedly brush away pulverized coal on
coal particle surface; weigh the mass (m1) of above-sieve substances, accurate to 0. 000
2 g.
8.2 Place the weighed coal particles on mesh spoon (6.6); immerse into molten paraffin
wax (5.1) that has been pre-heated to (70~80)°C by small aluminum pan; maintain paraffin
wax temperature at (60~80)°C; use glass rod to quickly scatter the coal particles, until there
is no air bubbles. Take out the mesh spoon immediately; after cooling slightly, spread the
coal particles onto glass plate (6.7); and use glass rod to scatter the coal particles quickly
so that they do not stick to each other. Cool to room temperature. Weigh the mass of waxed
coal particles (m2), accurate to 0. 000 2 g.
8.3 Put the waxed coal particles into density bottle (6.3); add sodium dodecyl sulfate
solution (5.2) to fill up to two thirds of density bottle. Plug the stopper; shake with hands or
tap density bottles with fingers gently, until there is no air bubbles on surface of waxed coal
particle; then add solution until it is about 1 cm away from bottle neck [Translator note. 1cm
below the bottle neck]. Place density bottle in a thermostat (6.10); maintain a constant
temperature at (20±0.5)°C for 1 h, or leave it at room temperature for over 3 h; and write
down the solution temperature.
8.4 Use pipette to add solution to the bottle drop-by-drop; plug the bottle stopper carefully
so that the excess solution can overflow from the upper end of capillary tube of bottle
stopper. Ensue that there is no air bubble in bottle and in capillary tube.
8.5 Quickly wipe the density bottle to dry. Weigh immediately (m3), accurate to 0. 0002 g.
8.6 Determination of blank value. Determine the blank value while measuring coal sample.
Operate according to 8.3 and 8.4 (without adding coal sample). Weigh the mass (m4) of
density bottle and aqueous solution, accurate to 0. 0002 g. The difference of measured
values of the same density bottle for two successive times must not exceed 0.0100g.
8.7 For coal sample of which the particle size is less than 10 mm, its apparent relative
density may be calculated according to Annex A, but it shall be indicated in the report.
13 0. 999 64 29 0.996 21
14 0. 999 51 30 0.995 91
15 0. 999 37 31 0.995 61
16 0. 999 21 32 0.995 30
17 0. 999 04 33 0.994 97
18 0. 998 86 34 0.994 64
19 0. 998 67 35 0. 994 30
20 0. 998 47 40 0. 992 48
10 Precision of method
Repeatability and reproducibility critical difference of apparent relative density are shown
in Table 2.
Table 2 Determination precision of apparent relative density of coal
Ash content Ad or Total Sulfur S t,d Repeatabil ity Limit
Ad≤30% and St,d≤2% 0. 04
Ad>30% or St,d>2% 0. 08
Annex A
(Normative)
Empirical Formula of Calculating Apparent Relative Density
Based on True Relative Density
When apparent relative density cannot be determined, apparent relative density of coal
may be calculated based on true relative density of coal. Standard uncertainty of its
calculated values are generally not greater than 0.03%; for the coal of which the ash
content is greater than 30% or sulfur c...
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