ASTM D2797-85(1999)
(Practice)Standard Practice for Preparing Coal Samples for Microscopical Analysis by Reflected Light
Standard Practice for Preparing Coal Samples for Microscopical Analysis by Reflected Light
SCOPE
1.1 This practice covers laboratory procedures for the preparation of granular samples of bituminous coal and anthracite samples for examination with a microscope using reflected light illumination. It does not apply to the preparation of oriented blocks of coal.
1.2 The values stated in SI units shall be considered as standard; and inch-pound units shall be considered as approximate equivalents.
1.3 This standard does not purport to address the safety concerns 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 2797 – 85 (Reapproved 1999)
Standard Practice for
Preparing Coal Samples for Microscopical Analysis by
Reflected Light
This standard is issued under the fixed designation D 2797; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This practice covers laboratory procedures for the 4.1 Briquets of granular bituminous coals and anthracite
preparation of granular samples of bituminous coal and anthra- prepared in accordance with the laboratory procedures of this
cite samples for examination with a microscope using reflected practice will have flat, scratch-free surfaces suitable for exami-
light illumination. It does not apply to the preparation of nation with a microscope using reflected light illumination.
oriented blocks of coal. The polished surfaces of briquettes prepared by this practice
1.2 The values stated in SI units shall be considered as will contain particles representative of the original gross
standard; and inch-pound units shall be considered as approxi- sample.
mate equivalents. 4.2 Samples prepared by this practice are used for micro-
1.3 This standard does not purport to address the safety scopical determination of the reflectance of the organic com-
concerns associated with its use. It is the responsibility of the ponents in a polished specimen of coal (Test Method D 2798)
user of this standard to establish appropriate safety and health and for microscopical determination of the volume percent of
practices and determine the applicability of regulatory limita- physical components of coal (Test Method D 2799).
tions prior to use.
5. Apparatus
2. Referenced Documents
5.1 Grinder, Pulverizer, or Mill, for final crushing of the
2.1 ASTM Standards: sample to pass a 850-μm (No. 20) sieve. Mortar and pestle or
D 2013 Method of Preparing Coal Samples for Analysis other equipment suitable for reducing the particle size of a
D 2234 Test Methods for Collection of a Gross Sample of 250-g sample that already passes a 4.75-mm (No. 4) sieve until
Coal all of it passes a 850-μm (No. 20) sieve (see 6.5).
D 2798 Test Method for Microscopical Determination of 5.2 Coarse Riffle Sampler—a riffle with at least twelve
the Reflectance of Vitrinite in a Polished Specimen of divisions of not less than 12.7 mm ( ⁄2 in.) and not greater than
Coal 19.1 mm ( ⁄4 in.).
D 2799 Test Method for Microscopical Determination of 5.3 Fine Riffle Sampler —a riffle with at least twelve
Volume Percent of Physical Components of Coal divisions of not less than 3.2 mm ( ⁄8 in.) and not greater than
D 4596 Practice for Collection of Channel Samples of Coal 6.4 mm ( ⁄4 in.).
in the Mine 5.4 Sieves—a 4.75-mm (No. 4) and a 850-μm (No. 20) U.S.
E 11 Specification for Wire-Cloth Sieves for Testing Pur- Standard Sieve (Specification E 11).
poses 5.5 Molds—containers to hold the coal binder mixture while
the binder hardens.
3. Summary of Practice
5.5.1 The mold shall be capable of withstanding pressures
3.1 A representative sample is crushed to a specified particle up to 70 MPa (10 000 psi), and shall be made of separable parts
size, air-dried, mixed with a binder, and formed into a briquet.
so that the briquet can be ejected after it has hardened.
The briquet is then polished to a flat, scratch-free surface for 5.5.2 The mold shall be large enough to provide a plane area
examination by vertical illumination.
of 4 cm or more on one side of the briquet. (Designs of
suitable 25-mm (1-in.) and 32-mm (1 ⁄4-in.) inside-diameter
molds are shown in Fig. 1).
This practice is under the jurisdiction of ASTM Committee D-5 on Coal and
5.6 Hydraulic Press—a press that is capable of producing a
Coke and is the direct responsibility of Subcommittee D05.28 on Petrographic
pressure up to 35 MPa (5000 psi) on the briquet, and has an
Analysis of Coal and Coke.
attachment to eject the briquet after solidification of the binder.
Current edition approved Aug. 30, 1985. Published October 1985. Originally
published as D 2797 – 69 T. Last previous edition D 2797 – 85.
Annual Book of ASTM Standards, Vol 05.06.
3 4
Annual Book of ASTM Standards, Vol 14.02. A suitable riffle sampler is made by Sepor Laboratory, PO Box 736, Ottawa, IL.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 2797 – 85 (1999)
6.1.2 The binder shall not react with the coal or the
atmosphere or expose the coal sample to a temperature above
100°C.
6.1.3 Under the microscope, the binder shall contrast mark-
edly with constituents being measured when immersed in oil
having an index of refraction of about 1.518.
6.1.4 The binder shall be such that a substantially flat and
scratch-free surface can be obtained as a result of the grinding
and polishing procedure.
NOTE 2—Relief, or difference in level, particularly between the coal
and the binder, is undesirable for reflectance determination. Although
relief depends a great extent on the polishing technique, use of a binder
with a hardness comparable to that of the coal is very helpful.
NOTE 3—An epoxy resin has been found suitable. The resin is
composed of the diglycidyl ethers of bis-phenol-A and its homologs and
is diluted with butyl glycidyl ether. The resin is used with an activator
composed of aliphatic polyamines or their adducts or both. The amount of
activator is calculated from the equation:
A 5 100 M /EH (1)
A
where:
A = amount of activator, parts per 100 (by weight) of
resin diluent mixture;
M = molecular weight of activator;
A
E = epoxide equivalent weight of epoxy-diluent mixture;
and
H = number of active hydrogens per molecular of acti-
NOTE 1—Material: cold rolled or stainless steel. Dimensions a and b
vator.
(inside diameters) are nominally 32 mm (1 ⁄4 in.) and 25 mm (1 in.). If an
6.2 Release Agent—Any preparation that does not damage
automatic polishing attachment is to be used, these dimensions should be
the molds or adversely affect the coal or mounting medium
specified to yield a briquet fitting snugly in the briquet holder.
FIG. 1 Molds Suitable for Briquetting Coal Samples may be used to coat the inside of the mold and facilitate
ejection of the briquet.
6.3 Grinding Abrasives—Water-resistant, adhesive-backed
5.7 Grinding and Polishing Equipment—one or several laps
silicon carbide papers of grit Nos. 240, 320, 400, and 600. Two
on which the coal briquet can be ground and polished to a flat,
or three of these are used according to a plan such as one of
scratch-free surface. Laps may be made of aluminum, iron,
those listed in Table 1.
brass, bronze, lead, glass, wax, or wood. For notes on grinding
6.4 Polishing Abrasives—Aluminum oxide powders of 3-,
and polishing practices, see Appendix X1.
1-, 0.3-, 0.1-, and 0.05-μm sizes. Two or three of these are used
NOTE 1—Equipment that has 203-mm (8-in.) diameter disk laps, according to a plan such as one of those listed in Table 1.
gear-driven at 160 to 170 r/min, and that has an automatic sample holder
6.5 Lap Coverings—Nap-free cloths of cotton and silk, and
attachment is recommended.
chemotextile material backed with water-resistant adhesive.
5.8 Sample Cleaner—some equipment is essential for 6.6 Detergent—Any nonoxidizing detergent may be used
for cleaning briquets after each grinding or polishing stage.
cleaning coal briquets between the different grinding or pol-
ishing stages. This may be a simple stream of water or an air
7. Sampling
jet, but an ultrasonic cleaner is recommended.
7.1 Obtain samples (Note 4) of coal in accordance with Test
5.9 Containers—if samples are to be transported or stored
before briquets are prepared, glass jars, bottles, or metal cans Methods D 2234 and Practice D 4596, when appropriate.
7.2 If the coal sample has not previously been air dried,
having tight-fitting closures shall be used. Metal cans shall
have plastic liners. bring the sample to room conditions by exposure to the
laboratory atmosphere.
6. Materials
6.1 Binder—Any binding material fulfilling the following
Armstrong epoxy resin C-4 with activator “D,” supplied by Armstrong
requirements may be used for preparing the coal briquet:
Products Co., Inc., Warsaw, IN, and Helix Bonding Agent R-283 with hardner B,
6.1.1 The binder shall hold all coal particles securely during
supplied by Carl H. Biggs Co., Inc., 1547 14th St., Santa Monica, CA, are suitable.
grinding, polishing, and observing the sample. Orthofre Separator, produced by Vernon-Benshoff Co., Pittsburgh, PA, and
S-122 Fluorocarbon release agent, produced by Miller-Stephenson Chemical Co.,
Inc., Chicago, IL have been found suitable for this purpose. The precautions listed
on the label should be followed when using the first material.
5 8
Buehler, Lt., 2120 Greenwood St., Evanston, IL, and Geoscience Instruments Texmet, supplied by Buehler, Ltd., 2120 Greenwood St., Evanston, IL, and
Corp., 110 Beckman St., New York,
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.