ASTM D409 / D409M - 12

    Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method

    Active Standard ASTM D409 / D409M | Developed by Subcommittee: D05.07

    Book of Standards Volume: 05.06


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    Significance and Use

    3.1 This test method develops a measurement of grinding or pulverizing characteristics that can be used to evaluate the yield, or energy input, or both, required in a grinding or pulverizing process, which can impact a wide variety of processes, including combustion, coke-making, liquefaction, and gasification.

    1. Scope

    1.1 This test method2 covers the determination of the relative grindability or ease of pulverization of coals in comparison with coals chosen as standards. A prepared and sized sample receives a definite amount of grinding energy in a miniature pulverizer, and the size consist of the pulverized product is determined by sieving. The resultant size consist is used to produce an index relative to the ease of grinding [Hardgrove Grindability Index (HGI)].

    1.1.1 Some coals, such as some high-volatile bituminous, subbituminous, and lignite coals, can undergo physical change as the natural or seam moisture is released during handling and preparation. This change is often sufficient to alter the grindability characteristics that will be reported when tested in the laboratory and could produce different indices dependent on the conditions of drying and the moisture level of the 1.18 × 0.60 mm (No. 16 × 30) (see Test Method D4749) materials used for the test. Therefore, the repeatability and reproducibility cited in this test method may not apply for these high-volatile bituminous, subbituminous, and lignite coals.

    1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

    1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D2013 Practice for Preparing Coal Samples for Analysis

    D2234/D2234M Practice for Collection of a Gross Sample of Coal

    D3302 Test Method for Total Moisture in Coal

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

    D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material

    D6883 Practice for Manual Sampling of Stationary Coal from Railroad Cars, Barges, Trucks, or Stockpiles

    D7430 Practice for Mechanical Sampling of Coal

    E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves


    ICS Code

    ICS Number Code 73.040 (Coals)

    UNSPSC Code

    UNSPSC Code 15101601(Coal)


    DOI: 10.1520/D0409_D0409M-12

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