1、Designation: E 1568 03 (Reapproved 2008)1Standard Test Method forDetermination of Gold in Activated Carbon by Fire AssayGravimetry1This standard is issued under the fixed designation E 1568; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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.1NOTEWarning notes were editorially revised throughout in November 2008.1. Scope1.1 This test method covers th
3、e determination of gold inactivated carbon by fire assay collection and gravimetricmeasurement. It covers the range of 15 g to 5000 g/g gold.1.2 The values stated in SI units are to be regarded as thestandard. The inch-pound values given in parentheses are forinformation only and are not considered
4、standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For s
5、pecific hazardsstatements, see Section 9 and 11.2.3-11.2.5, 11.3.4, and 11.3.4.2. Referenced Documents2.1 ASTM Standards:2D 2862 Test Method for Particle Size Distribution ofGranular Activated CarbonD 2866 Test Method for Total Ash Content of ActivatedCarbonD 2867 Test Methods for Moisture in Activa
6、ted CarbonE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores,
7、 and Related MaterialsE 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals3E 276 Test Method for Particle Size or Screen Analysis atNo. 4 (4.75-mm) Sieve and Finer for Metal-Bearing Oresand Related MaterialsE 300 Practice for Sampling Industrial ChemicalsE
8、882 Guide for Accountability and Quality Control in theChemical Analysis LaboratoryE 1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical Method3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Su
9、mmary of Test Method4.1 The weighed test sample is ignited and fused with fireassay flux in a clay crucible. The lead metal from the fusion isseparated and the precious metals concentrated by oxidationand adsorption of the lead on a cupel, the silver is parted withnitric acid, and the gold is anneal
10、ed and weighed on amicrobalance.5. Significance and Use5.1 In the primary metallurgical processes used by themineral processing industry for gold bearing ores, gold isextracted with alkaline cyanide solutions and adsorbed ontoactivated carbon for recovery of the metal. Metallurgicalaccounting, proce
11、ss control, and ore evaluation procedures forthis type of mineral processing plant depend on accurate,precise, and prompt measurements of gold concentrations inthe activated carbon.5.2 This test method for gold in activated carbon is intendedprimarily as a referee method to test such materials for m
12、etalcontent. It is assumed that those who use these procedures willbe trained analysts capable of performing common laboratoryprocedures skillfully and safely. It is expected that work will be1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, a
13、nd Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved Nov. 1, 2008. Published December 2008. Originallyapproved in 1993. Last previous edition approved in 2003 as E 1568 03.2For referenced ASTM
14、 standards, 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.3Withdrawn. The last approved version of this historical standard is referencedon
15、 www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.performed in a properly equipped laboratory and that properwaste disposal procedures will be followed. Appropriate qual-ity control practices must be followed, such as tho
16、se describedin Guide E 882.6. Interferences6.1 Elements normally found in ore processing activatedcarbon do not interfere. When present, platinum group metalsmay be reported as gold in gravimetric fire assay determina-tions and must be less than 0.1 mg in the final gold bead.7. Apparatus7.1 Analytic
17、al Balance, capable of weighing to 0.1 g.7.2 Assay Mold, 100-mL capacity.7.3 Cupel, magnesite, 30-g lead capacity.7.4 Drying Oven, having forced air circulation, with tem-perature control between 145 C and 155 C.7.5 Fire Clay Crucible, 30-g sample capacity.7.6 Hot Plate, having variable temperature
18、control, usedwith ventilation control for acid fumes.7.7 Jewelers Rolls, capable of flattening dor beads.7.8 Muffle Furnace, having air circulation with draft con-trols, capable of temperatures to 1100 C, accurate to 6 10 C,used with ventilation controls for lead fumes.7.9 Semi-Microbalance, capable
19、 of weighing to 0.01 mg.7.10 Roasting Dish, 15-g sample capacity.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the America
20、n Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Ammonia Wash Solution, NH4OH (1 + 17)Add100 mL NH4OH to 1700 m
21、L of water.8.3 BoraxNa2B4O7Sodium borate powder, with goldcontent less than 0.001 g/g.8.4 Fire Assay Flux MixtureMix 575 g of litharge (PbO)with 275 g of soda ash (Na2CO3), 75 g of borax (Na2B4O7),75 g of silica (SiO2), and 30 g of baking flour.8.5 Lead Foil99.9 % minimum, with gold content lessthan
22、 0.001 g/g.8.6 PbOLead oxide powder, with gold content less than0.001 g/g.8.7 SiO2Silicon dioxide powder, with gold content lessthan 0.001 g/g.8.8 Silver Foil99.9 % minimum, with gold content lessthan 0.001 g/g.8.9 Na2CO3Sodium carbonate powder, with gold contentless than 0.001 g/g.8.10 Strong HNO3(
23、1 + 2) Parting SolutionAdd 330 mLHNO3to 660 mL of water.8.11 Weak HNO3(1 + 4) Parting SolutionAdd 200 mLHNO3to 800 mL water.9. Hazards9.1 Refer to Practices E50for precautions to be observed inthis test method.9.2 Use care when handling hot crucibles and operatingfurnaces in order to avoid personal
24、injury by either burn orelectrical shock.9.3 Lead and PbO are toxic materials and are volatile atrelatively low temperatures. Use accepted safety procedures toavoid inhalation, ingestion, or skin contact.9.4 Refer to 11.2.3-11.2.5, 11.3.4, and 11.3.4.10. Sampling10.1 Collect the sample in accordance
25、 with Practice E 300.Samples must be free of any extraneous materials such as sand,rocks, and wood.10.2 Sample PreparationDry the sample, in accordancewith the Oven-Drying Method of Test Methods D 2867,toconstant weight at 150 C. If the analysis of a particularparticle size range is desired, separat
26、e fractions in accordancewith Test Method D 2862.10.3 Test SamplePulverize the gross sample so that atleast 90 % passes a 150-m (100 mesh, Tyler) sieve, inaccordance with Test Method E 276. Mix the gross sample.Weigh duplicate test samples of 15.0 g 6 1.0 g, and record thetest sample weights.11. Pro
27、cedure11.1 Ignition:11.1.1 Spread5gofSiO2in the bottom of a preheatedroasting dish.11.1.2 Transfer the test sample to the top of the silica bed inthe roasting dish.11.1.3 Ash at 650 C in a muffle furnace in accordance withTest Method D 2866. Cool.11.2 Fusion:11.2.1 Transfer calcine and silica to a c
28、lay crucible contain-ing 50 g of fire assay flux.11.2.2 Cover with another 50 g portion of fire assay flux.Mix. Cover the mixture of5gofPbO.11.2.3 Place the crucible in a muffle furnace at 1050 C for1h.(WarningFire assay products produce toxic lead oxidefumes when heated. Use protective clothing, an
29、d work only inwell-ventilated areas.)NOTE 1Draft may be required for the first 15 min of fusion to preventboil-over.11.2.4 Remove the crucible from the muffle furnace andpour molten liquid into the assay mold carefully, makingcertain that all lead droplets are transferred to the mold.(WarningRapidly
30、 cooling slag may eject flying glass. Useeye protection and cover the slag immediately after pouring.)4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC, http:/www.chemistry.org. For suggestions onthe testing of reagents not listed by the American
31、Chemical Society, see AnnualStandards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., http:/, and the United States Pharmacopeia and National Formulary, U.S.Pharmacopeial Convention, Inc. (USPC), Rockville, MD, http:/www.usp.org.E 1568 03 (2008)1211.2.5 After cooling, separate the lead meta
32、l from the slag.Form the lead metal into a cube using a hammer and metalplate. (WarningLead slag is toxic; use protective equipmentand dispose of waste properly.)11.3 Cupellation:11.3.1 Preheat a cupel at 1000 C for 10 min in a mufflefurnace. Reduce the muffle furnace temperature controller to940 C.
33、11.3.2 Place the lead buttons on the hot cupels and melt,without draft, as the temperature drops to 940 C (approxi-mately 5 min).11.3.3 Open the draft when the lead is melted, and continueheating with the draft open until the lead has been removed,leaving the dor bead in the cupel.NOTE 2A row of emp
34、ty cupels should be placed in the front of themuffle furnace for temperature control of the draft.11.3.4 Vent the muffle furnace and remove the cupel fromthe furnace. Cool. (WarningHot cupels emit lead fumes.Use proper ventilation.)11.4 Inquartation:11.4.1 Carefully remove the dor bead from the cupe
35、l andweigh on the semimicrobalance to the nearest 0.01 mg. Recordthe dor weight. (WarningUsed cupels are toxic; use pro-tective equipment and dispose of waste properly.)11.4.2 Weigh the proper amount of silver foil for the dorweight, according to Table 1, to the nearest 1 mg.11.4.3 Wrap the dor bead
36、 and silver foil in 10 g of lead foil.11.4.4 Repeat the cupellation procedure (11.3) with the foilpacket.11.5 Parting:11.5.1 Flatten the dor bead and place it in a 50-mLporcelain crucible.NOTE 3The use of jewelers rolls is recommended for flattening largedor beads.11.5.2 Anneal the bead in the cruci
37、ble at 650 C in a mufflerfurnace or over a bunsen burner.11.5.3 Place the crucible on a hot plate at 95 C and add 25mL of HNO3(1 + 4), preheated to 60 C 6 10 C. Heat for 30min.11.5.4 Carefully decant spent parting solution and discard.11.5.5 Repeat the parting steps given in 11.5.3 and 11.5.4,using
38、HNO3(1 + 2). Cool.11.5.6 Rinse with 25 mL of NH4OH (1 + 17) and five timeswith 25 mL water. Dry on a hot plate.11.5.7 Repeat the annealing step given in 11.5.2. Cool.11.6 GravimetryWeigh the gold bead to the nearest 0.01mg. Record the weight. If silver is detected visually in the goldbead, repeat th
39、e steps given in 11.4.3-11.5.7, reweigh, andrecord the weight.12. Calculation12.1 Calculate the g/g gold in the sample as follows:Gold, g/g 5 1000 A/B (1)where:A = gold measured, mg, andB = test sample weight, g.12.2 Average the results from duplicate determinations, andround them to the nearest 1 g
40、/g in accordance with PracticeE29.13. Precision and Bias13.1 PrecisionAn interlaboratory study was conducted inaccordance with Practice E 173 to establish the within-laboratory and between-laboratory precision. Three materialswere tested by seven laboratories. The results are summarizedin Table 2.51
41、3.2 BiasNo information concerning the bias of this testmethod is available. However, the bias of the test method in asingle laboratory, or between laboratories, may be judged bythe deviation of the mean value obtained using the test methodfrom the accepted value for a suitable reference material.NOT
42、E 4The within-laboratory precision measures the maximum dif-ference expected in testing the material in a single laboratory at 95 %confidence. The between-laboratory precision measures the maximumdifference expected in testing the material in more than one laboratory at95 % confidence.NOTE 5This tes
43、t method has been evaluated in accordance withPractice E 173. The Reproducibility R2of Practice E 173 corresponds tothe Reproducibility Index R of Practice E 1601. The Repeatability R1ofPractice E 173 corresponds to the Repeatability Index r of PracticeE 1601.14. Keywords14.1 activated carbon; gold
44、content5Support data have been filed at ASTM International Headquarters. RequestRR:E01-1007.TABLE 1 Silver Additions for InquartationDor Weight Range,mgSilver Foil Weight Factor Appliedto the Dor Weight0.00 to 0.1 300.1to0.2 100.2to1.0 60.1 to 10.0 4 10.0 2.25TABLE 2 Interlaboratory PrecisionMateria
45、lMeanAu, g/gR1; PracticeE 173Au, g/gR2; PracticeE 173Au, g/gStripped carbon 108.2 5.4 7.6Fine carbon 347.8 17.6 17.6Loaded carbon 3983 99.5 243E 1568 03 (2008)13ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this sta
46、ndard. 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 and must be revi
47、ewed 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 of theresponsib
48、le 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 Box 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).E 1568 03 (2008)14
