1、Designation: D 5671 95 (Reapproved 2005)Standard Practice forPolishing and Etching Coal Samples for MicroscopicalAnalysis by Reflected Light1This standard is issued under the fixed designation D 5671; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers laboratory procedures for preparingan etched, polished surface of
3、granular and block samples ofcoal for examination with a microscope using reflected lightillumination.1.2 The values stated in SI units shall be considered asstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of
4、the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 121 Terminology of Coal and CokeD 2797 Practice for Preparing Coal Samples for Micro-scopical Analysis
5、by Reflected LightD 2798 Test Method for Microscopical Determination ofthe Vitrinite Reflectance of CoalD 2799 Test Method for Microscopical Determination ofthe Maceral Composition of CoalD 4596 Practice for Collection of Channel Samples of Coalin a MineD 5192 Practice for Collection of Coal Samples
6、 from Core3. Terminology3.1 Terminology used in this standard can be found inTerminology D 121.4. Summary of Practice4.1 A subsplit of a representative sample obtained in accor-dance with Practice D 4596 and prepared in accordance withPractice D 2797 or a block of coal obtained in accordance withPra
7、ctice D 5192 is polished to a flat, scratch-free surface, thereflectance of vitrinite is determined on a subsplit in accor-dance with Test Method D 2798, and then other subsplits arechemically etched using an acidified potassium permanganatesolution.5. Significance and Use5.1 Components observable i
8、n surfaces of coal samplesprepared in accordance with the laboratory procedures of thispractice will have differential relief that will aid in theirmaceral identification by visual classification and enablesidentification of plant parts or tissues that formed the coal.5.2 Samples prepared by this pr
9、actice can be used formicroscopical determination of the volume percent of physicalcomponents of coal in accordance with Test Method D 2799.6. Apparatus6.1 Ultrasonic Cleanerlarge enough for sample holderand sample preparations to be immersed in cleaning solution.6.2 Beakersglass beakers, 50, 100, a
10、nd 500 ml capacity,one each for each etching setup.6.3 Stirring Rodsglass, approximately 20 cm long.6.4 Hot Plateelectric or gas-heated with capability fortemperature control and rotating stirring magnets.6.5 Watch Glassesglass, 100200 mm in diameter de-pending on size of specimen blocks to be etche
11、d.6.6 Graduated Cylindersglass, 25 and 100 ml.6.7 Grinding and Polishing Equipmentone or several lapson which the coal briquets or blocks can be ground andpolished to a flat, scratch-free surface. Laps may be made ofaluminum, iron, brass, or bronze.1This practice is under the jurisdiction of ASTM Co
12、mmittee D05 on Coal andCoke and is the direct responsibility of Subcommittee D05.28 on PetrographicAnalysis of Coal and Coke.Current edition approved Sept. 15, 2005. Published October 2005. Originallyapproved in 1995. Last previous edition approved in 2001 as D5671 - 95(2001).2For referenced ASTM st
13、andards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken
14、, PA 19428-2959, United States.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specification
15、s are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the quality of theetch.7.2 Potassium Permanganate (KMnO4), crystals.7.3 Sodium Sulfite (Na2SO3), anhydrous, granular.7.4 Sulfuric Acid (H2SO4)
16、, 47 % H2SO4.7.5 Sodium Hydroxide solution, dissolve 10 g NaOH crys-tals in 90 g deionized water at room temperature.8. Materials8.1 Grinding AbrasivesWater-resistant, adhesive-backedsilicon carbide papers of 45, 32, and 15 m (240, 400, and 600grit). Two or more of these can be used according to a p
17、lansuch as one of those listed in Table 1.8.2 Polishing AbrasivesLevigated aluminum oxide pow-ders of 1.0 m size (aqueous suspension) and colloidal silica of0.06 m size (in a prepared NaOH suspension).8.3 Lap CoveringsChemotextile material backed withwater-resistant adhesive or similar quality lap c
18、overings. Rec-ommendations of the manufacturer of the polishing abrasiveused should be followed for choice of lap covering.8.4 Diamond Impregnated Lap WheelImpregnated withdiamonds of 6 m size.8.5 Detergent or Sonic Cleaning SolutionAny nonoxidiz-ing detergent may be used for cleaning sample surface
19、s aftereach grinding and polishing stage.8.6 BinderA potting epoxy resin and hardener or pottingpolyester resin and hardener that has a curing temperature lessthan 100C.8.7 Sample MoldsPrepared for block samples and is madefrom potting-type silicone rubber.8.8 Release AgentSpray silicon or any other
20、 preparationthat does not damage the molds or adversely affect the coal ormounting medium may be used to coat the inside of thebriquette mold and facilitate ejection of the briquet.NOTE 1Molds prepared from silicone rubber as described in Appen-dix X1 do not require release agent.9. Sample Preparati
21、on9.1 Coal Briquets:9.1.1 Prepare granular samples as briquets in accordancewith Practice D 2797.9.2 Coal Blocks:9.2.1 Obtain specimens from core or as blocks of coal froma mining face.9.2.2 Trim specimens to about 0.5 mm smaller than thevolume of the silicone rubber molds.9.2.3 Air dry the specimen
22、s to remove visible surfacemoisture.NOTE 2Overdrying specimens of low rank coals at any point inpreparation can cause slaking or severe desiccation of specimen. Incontrast, underdrying of specimens will prevent epoxy from settingproperly.9.2.4 Mix resin and hardener according to manufacturersinstruc
23、tions.9.2.5 Place specimens and labels into silicone rubber moldsand pour resin mixture over the specimens and labels up to thelevel of the top of the molds. Allow to cure, then remove thespecimens from the molds.10. Preparation of Sample Surface10.1 Grind and polish on the base surfaces of the briq
24、uet orblock on a lap in a wet slurry to obtain a surface suitable formicroscopical examination. Grinding and polishing should bedone with automated equipment. Use a series of abrasives ofdecreasing particle size according to a plan such as one of thosedescribed in Table 1.11. Determination of Etchin
25、g Time11.1 In this procedure, the etching time is determined fromthe relationship between optimum etching time and measuredreflectance of unetched polished vitrinite (Fig. 1).11.1.1 Measure reflectance of vitrinite on a subsplit inaccordance with Test Method D 2798.11.1.2 Using the relationship show
26、n in Fig. 1, determine theetching time required for obtaining an optimum etch of thepolished sample surface.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, s
27、ee Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.TABLE 1 Suggested Plans for Grinding and Polishing ofBriquets and BlocksPlanNo.Grinding with Silicon Carbide
28、 Paper PolishingStage 1 Stage 2 Stage 3 Stage 1 Stage 21 45 m(240 grit)22 m(400 grit)15 m(600 grit)1 m Alumina 0.06 mColloidalSilica222m(400 grit)15 m(600 grit). 1 m Alumina 0.06 mColloidal SilicaFIG. 1 Determination of Etching Time for Coal on the Basis ofMeasured Vitrinite ReflectanceD 5671 95 (20
29、05)212. Etching Procedure412.1 Preparation of etching solution: To 100 ml deionizedwater, add and mix 25 g KMnO4,and5mlH2SO4(concentrated). Caution: always add acid to water.12.2 Preparation of rinsing solution: To 100 ml deionizedwater, add 25 g Na2SO3and5mlH2SO4. Stir solution until allNa2SO3has d
30、issolved.12.3 Heat the etching solution in a water bath until most ofthe KMnO4has dissolved.12.4 Pour part of the heated solution into a watch glass andsubmerse the polished coal surface in the etching solution forthe time as determined from Fig. 1 and in accordance with11.1.12.5 Remove the coal sur
31、face from the solution and imme-diately rinse with flowing deionized water for 23 s to removeetching solution.12.6 Submerse the coal surface into the rinsing solution forone min or until all purplish stain has been removed.12.7 Clean the coal surface ultrasonically in deionized waterfor one minute.1
32、2.8 Dry the surface with a stream of compressed airimmediately after removing from ultrasonic bath.NOTE 3For some samples, a small area of the polished surface can bemasked using cellophane tape smoothed so as to prevent any etchingeffects.3After etching, this tape is removed which produces a line t
33、hatdemarcates the etched and unetched areas.NOTE 4For block samples of low rank coal, primarily less than 0.5 %reflectance, blocks can be stored in a shallow bath of deionized water toprevent slaking or severe drying. Prior to examination, the sample surfacecan be dried with a stream of compressed a
34、ir. Some low rank coals mayalso require using a diluted etching solution for the time shown in Fig. 1.13. Keywords13.1 coal microscopical analysis; etching; polishingAPPENDIX(Nonmandatory Information)X1. PREPARATION OF SILICONE RUBBER MOLDS FOR COAL BLOCKS5X1.1 Construct a wooden block that will fit
35、 the blockholder of the grinding and polishing equipment. This woodenblock will be the size of the samples that will be prepared. Sandall sides of the wooden block to remove severe scratches(generally to a sanding fineness of about 90 m (120 grit).X1.2 Construct a mold holder using a smooth surfaced
36、cardboard box that is at least 1 cm larger in all dimensions thanthe wooden block.X1.3 Mix part of the silicone rubber according to manu-facturers directions and pour a layer of rubber that is about 1cm thick into the bottom of the mold holder. Allow rubber tocure.X1.4 Place the wooden block centere
37、d, on top of the layerof cured rubber, pour mixed silicone rubber around the outsideof the mold up to level with the surface of thewooden block(Fig. X1.1). Allow rubber to cure.X1.5 Eject the wooden block from the mold. Mold is readyto use for coal block sample preparation.4Modified from procedure o
38、utlined in Stach, Ernst, 1935, Lehrbuch derKohlenpetrographie: Berlin, Borntraeger, 293 p.; Teichmller, M. L., 1941, The finestructures of American coals in polished samples and thin sections: Reichsamt frdas Jahr 1940, Band 61, p. 2055.5Adapted from Moore, T.A., 1991, “Using Silicone Rubber Molds,”
39、 The Societyof Organic Petrology Newsletter, vol 8, no. 2, p. 45.FIG. X1.1 Cross Section View of Materials Used to Prepare aSilicone Rubber Mold for Coal BlocksD 5671 95 (2005)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item ment
40、ionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee
41、and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting
42、 of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO B
43、ox C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 5671 95 (2005)4
