ASTM D4749

ASTM D4749 – Standard Test Method for Performing the Sieve Analysis of Coal and Designating Coal Size

Description:

Significance and Use

4.1 This test method concerns the sieving of coal into designated size fractions for the purpose of characterizing the material as to its particle size distribution for further processing or for commercial purposes. This is covered in Part A of this standard. Raw, as well as prepared (crushed, cleaned, or screened), coals can be tested by this test method.

4.2 This test method is applicable for all types of coals, except for pulverized coals (see Method D197) such as fed into steam boilers. Low rank coals, that is, lignites, subbituminous, and high volatile bituminous C, must be dried with caution and handled with care to minimize deterioration or size degradation during sieving.

4.3 This test method is applicable for the wet or dry-sieving of coal at sizes from 200 mm [8 in.] to 38 μm [No. 400 U.S.A. Standard]. Methods for sizing materials below 38 μm are outside the scope of this test method.

Note 2: The sizing of material that passes the 38 μm sieve is normally performed by optical microscopy, sedimentation, centrifugation, light scattering or obfuscation, surface area measurement, or other such methods. Subsieve techniques are also used sometimes.

4.4 This test method also concerns the designation of a coal sample as to its upper (nominal top-size) and lower (nominal bottom-size) limiting sizes for the purpose of characterizing the material for further processing or for commercial purposes. This is covered in Part B of this test method. Anthracite coal is further designated by a one word descriptive term (see 14.4).

4.5 Enough material may not be collected by this test method to meet subsequent test procedures, such as washability analyses (Test Method D4371).

Scope

1.1 This test method covers procedures for determining the sieve analysis of coal and designating the size of coal from sieve analysis data. Raw as well as prepared (crushed, cleaned or screened) coals can be tested by this test method.

1.2 This test method explains how to designate coal sizes from the results of sieve analysis data in order to represent the condition of the coal as sold. In the case of special mixtures or coals with noncontinuous ranges of sizes, a sufficiently complete sieve analysis must be made to properly describe the size distribution.

1.3 This test method is not applicable for determining the sieve analysis nor for designating the size of pulverized coal. (See Note 1.) Size fractions down to and including 38 μm [No. 400 U.S.A. Standard Series] can be treated by the methods discussed in this test method. Methods for handling size fractions below 38 μm [No. 400] will be developed by this committee.

Note 1: For powdered or pulverized coal as is fired into steam boilers, refer to Test Method D197.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.