1、Designation: E2941 13E2941 14Standard PracticePractices forNitric Acid-Extraction Extraction of Elements from Ores andRelated Metallurgical Materials by Closed Vessel MicrowaveHeatingAcid Digestion1This standard is issued under the fixed designation E2941; the number immediately following the design
2、ation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice coversThese practi
3、ces cover the digestion of ores and related metallurgical materials, such as mine soil, wasterock and tailings, for subsequent determination of nitric acid-extractable contents of certain elements by such solution analyticaltechniques as atomic absorption, absorption spectrometry (AAS), atomic emiss
4、ion spectrometry (ICP-AES), (see Test MethodD1976), and inductively coupled plasma mass spectroscopy spectrometry (ICP-MS) (see Test Method D5673).1.1.1 Contents of aluminum, antimony, arsenic, barium, beryllium, bismuth, boron, cadmium, calcium, chromium, cobalt,copper, gallium, iron, lead, lithium
5、, magnesium, manganese, mercury, molybdenum, nickel, phosphorus, potassium, scandium,selenium, silver, sodium, strontium, thallium, tin, titanium, vanadium and zinc can be extracted from ores and related metallurgicalmaterials for determination by analytical methods for elements in solution. Other e
6、lements may be determined from extractsproduced using this practice.1.1.2 Actual element quantification in digested solutions can be accomplished by following the various test methods under otherappropriate ASTM standards for element(s) of interest in solution.1.1.3 The detection limit and linear co
7、ntent range for each element is dependent on the atomic absorption absorption, massspectrometry or emission spectrometric technique employed and may be found in the manual accompanying the instrument usedor ASTM standard method for analysis of the solutions. Take into account the 100 fold dilution d
8、ue to digesting a 1-g sample tofinal volume of 100 mL.dilution factor in content calculations due to digestion and dilution of solid samples.1.1.4 The extent of extraction of elements from ores and related metallurgical materials by this methodthese practices isdependent upon the physical and minera
9、logical characteristics of the prepared sample.sample and the digestion practice used.1.2 The digestion practices appear in the following order:SectionsNitric Acid Microwave Digestion 7 to 14Four-Acid Total Digestion 15 to 21.121.3 The values stated SI units are to be regarded as the standard. No ot
10、her units of measurements are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability
11、 of regulatorylimitations prior to use. For specific hazard statements, see Section 911.2. Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD1976 Test Method for Elements in Water by Inductively-Coupled Argon Plasma Atomic Emission SpectroscopyD5258 Practice for Acid-Extr
12、action of Elements from Sediments Using Closed Vessel Microwave HeatingD5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass SpectrometryE50 Practices forApparatus, Reagents, and Safety Considerations for ChemicalAnalysis of Metals, Ores, and Related MaterialsE135 Terminology Rel
13、ating to Analytical Chemistry for Metals, Ores, and Related Materials1 This test method is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommittee E01.02 on Ores, Concentrates, and Related Metallurgi
14、cal Materials.Current edition approved Oct. 1, 2013Nov. 1, 2014. Published October 2013January 2015. Originally approved in 2013. Last previous edition approved in 2013 asE2941-13. DOI: 10.1520/E2941-13.10.1520/E2941-14.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactA
15、STM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been ma
16、de to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Cop
17、yright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory2.2 Federal Standard:4CFR Title 21, Part 1030, and Title 47, Part 183. Terminology3.1 DefinitionsFor def
18、initions of terms used in this practice,these practices, refer to Terminology E135.4. Summary of Practice4.1 The chemical portion of this practice involves nitric acid digestion to dissociate the elements not interstitially bound insilicate lattices.4.2 The sample is digested with HNO3 in a closed f
19、luoropolymer vessel using microwave heating to an internal pressure of 6.89 105 Pa.4.3 This practice provides a sample suitable for analysis by atomic absorption, atomic emission or inductively coupled plasmamass spectrometry.4. Significance and Use4.1 These test methods practices are primarily inte
20、nded to test materials for compliance with compositional specifications andfor monitoring. Partial extraction of ores and related metallurgical materials can provide information on the availability of elementsto leaching, water quality changes, or other site conditions.5.2 Rapid heating, in combinat
21、ion with temperatures in excess of the atmospheric boiling point of HNO3, reduces samplepreparation or reaction times.5.3 Little or no acids are lost to boiling or evaporation in the closed digestion vessel so additional portions of acid may not berequired. Increased blank corrections from trace imp
22、urities in acid are minimized.4.2 It is assumed that the users of this practicethese practices will be trained analysts capable of performing common laboratoryprocedures skillfully and safely. It is expected that work will be performed in a properly equipped laboratory and that proper wastedisposal
23、procedures will be followed. Appropriate quality control practices such as those described in Guide E882 mustshall befollowed.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specific
24、ations of the committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.5 Other grades may be used provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.5.2
25、 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toType I or Type II of Specification D1193. Type III or Type IV may be used if they effect no measurable change in the blank orsample.6. Sampling and Sample Preparation6.1 Materials S
26、afetySamples shall be prepared, stored, and disposed of in accordance with the materials and safety guidelinesin Practices E50.6.2 Prepared SampleDry a representative portion of the gross sample at 80 C to constant mass in order to minimize sulfidemineral oxidation. Pulverize or grind the laboratory
27、 sample until at least 95 % passes a 150-m sieve. Fine grinding to 95 %passing a 53-m sieve is recommended for procedures using a single acid digestion.NITRIC ACID MICROWAVE DIGESTION7. Summary of Practice7.1 The chemical portion of this practice involves nitric acid digestion to dissociate the elem
28、ents not interstitially bound insilicate lattices.4 Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5 Reagent Chemicals, American Chemical Society Specifications, American Chemical Soci
29、ety, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals,the BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville
30、, MD.E2941 1427.2 The sample is digested with HNO3 in a closed fluoropolymer vessel using microwave heating to an internal pressure of 6.89 105 Pa.7.3 This practice provides a sample suitable for analysis by atomic absorption, atomic emission, or inductively coupled plasmamass spectrometry.8. Signif
31、icance and Use8.1 Rapid heating, in combination with temperatures in excess of the atmospheric boiling point of HNO3, reduces samplepreparation or reaction times.8.2 Little or no acids are lost to boiling or evaporation in the closed digestion vessel so additional portions of acid may not berequired
32、. Increased blank corrections from trace impurities in acid are minimized.8.3 HNO3 digestion of ores and related metallurgical materials are most useful for rapid, low-cost digestions, where metalslocked in the silica or other insoluble matrix components are not important for the results of the anal
33、ysis.9. Interferences9.1 No interferences to the digestion of ores and related metallurgical materials using microwave heating have been observed.9.2 Precautions should be exercised to avoid those interferences normally associated with the final determination of elementsusing atomic absorption, atom
34、ic emission, or inductively coupled plasma mass spectrometry.9.3 The HNO3 matrix may not be suitable for stabilizing solutions containing silver and antimony,antimony; an alternatedigestion method using a HCl or HF matrix may be required to determine some elements. elements (i.e. silicon).10. Appara
35、tus10.1 Microwave Heating SystemA laboratory microwave heating system capable of delivering a minimum of 570 W ofmicrowave energy.The system should be capable of 1 % power adjustments and 1 s time adjustment.The microwave cavity shouldbe fluoropolymer coated and equipped with exhaust ventilation suf
36、ficient to provide ten chamber exchanges per minute. The cavitymustshall have a 360 oscillating turntable to ensure even sample heating, and be capable of holding digestion vessels. Safetyinterlocks, to shut off magnetron power output, mustshall be contained in the cavity door opening door-opening m
37、echanism. Thesystem mustshall comply with Department of Health and Human Services Standards under Code of Federal Regulations, Part1030.10, Subparts (C) (1), (C) (2), and (C) (3), for microwave leakage. The system should have Federal CommunicationsCommission (FCC) type approval for operations under
38、FCC Rule Part 18.10.1.1 Digestion VesselsA vessel of 100-mL capacity. The vessel must be shallbe transparent to microwave energy and becapable of withstanding a minimum have an operating capability to withstand an internal pressure of at least 8.27 105 Pa, anda temperature of 200 C. The vessel musts
39、hall contain a safety pressure relief valve, a rupture disc, pressure venting system, orbe connected to an external safety relief valve that will prevent possible vessel rupture or ejection of the vessel cap.10.1.2 Pressure Control VesselA vessel of 100 mL capacity, transparent to microwave energy,
40、with a port for connection toa pressure control device and capable of withstanding a minimum an internal pressure of at least 8.27 105 Pa and temperatureof 200 C.10.1.3 Pressure Control DeviceAn externally or internally operated device to control the pressure within the digestion vessels.The control
41、ler mustshall be capable of 6.89 103 Pa adjustments, controlling up to 8.27 105 Pa and be equipped with an externalpressure relief valve if a non-venting control vessel is used.10.2 Other commercially available laboratory microwave heating systems may be used so long as they can be shown to providec
42、omparable safety and performance. Follow manufacturers instruction for use.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the committee on Analytical Reagents of t
43、he American Chemical Society, wheresuch specifications are available.4 Other grades may be used provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referen
44、ces to water shall be understood to mean reagent water conforming toType I or Type II of Specification D1193. Type III or Type IV may be used if they effect no measurable change in the blank orsample.11. Hazards11.1 For hazards to be observed in the use of reagents and apparatus in this practice, re
45、fer to Practices E50.E2941 14311.2 Operate and maintain the microwave system in accordance with the manufacturers recommended safety precautions. Donot operate the microwave system in a fume hood where it is surrounded by acid fumes that can cause corrosion of the equipment.Vent acid fumes generated
46、 inside the cavity from the cavity to a fume hood. Place the digestion vessels in a fume hood to removevapors released when a vessel is opened.11.3 Perform the digestion in accordance with the manufacturers recommended safety precautions.11.4 Use of other domestic and commercial microwave systems no
47、t designed for nitric acid digestion of samples may not besuitable for use with this practice.10. Sampling10.1 Materials SafetySamples must be prepared, stored, and disposed of in accordance with the materials and safetyguidelines in Practices E50.10.2 Prepared SampleDry a representative portion of
48、the gross sample at 80 C to constant mass in order to minimize sulfidemineral oxidation. Pulverize or grind the laboratory sample until at least 95 % passes a 150-m sieve. Fine grinding to 95 %passing a 53-m sieve, is recommended for procedures using a single acid digestion.12. Preparation of Appara
49、tus12.1 The manufacturers recommended cleaning procedure may be followed or the following procedure in 11.2 through11.4may be used.12.2 Soak the fluoropolymer vessel parts in HNO3 (1+1) (1 + 1) cleaning solution at 60 C 6 5 C for 10 min.12.3 Remove the vessel parts from the cleaning solution and thoroughly rinse the parts with water.12.4 Allow the vessel parts to air-dry or wipe dry using a clean, soft cloth.13. Procedure13.1 Determine the power output of the microwave using the procedure described in the annex to ensure that the unit meets t
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