1、Designation: E 1568 03Standard Test Method forDetermination ofGold in Activated Carbon by Fire Assay Gravimetry1This 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 revision, the year of
2、 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 test method covers the determination of gold inactivated carbon by fire assay collection and gravimetricmeasure
3、ment. It covers the range of 15 to 5000 g/g gold.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibil
4、ity 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 specific hazardsstatements, see Section 9 and Notes 2-4, Note 6, and Note 7.2. Referenced Documents2.1 ASTM Standards:D 2862 Test Method
5、 for Particle Size Distribution ofGranular Activated Carbon2D 2866 Test Method for Total Ash Content of ActivatedCarbon2D 2867 Test Method for Moisture in Activated Carbon2E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3E 50 Practices for Apparatus
6、, Reagents, and Safety Precau-tions for Chemical Analysis of Metals4E 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Materials4E 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals5E 276 Test Method for Particle Size or Screen
7、Analysis atNo. 4 (4.75 mm) Sieve and Finer for Metal-Bearing Oresand Related Materials4E 300 Practice for Sampling Industrial Chemicals6E 882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory7E 1601 Practice for Conducting an Interlaboratory Studiesof Methods for Chemic
8、al Analysis of Metals42.2E 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals83. Terminology3.1 Definitions:For definitions of terms used in this test method, refer toTerminology E 135.4. Summary of Test Method4.1 The weighed test sample is ignited and fuse
9、d 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 annealed and weighed on amicrobalance.5. Significance and Use5.1 In the p
10、rimary 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, process control, and ore evaluation procedures forthis type of mineral p
11、rocessing 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 metalcontent. It is assumed that those who use these procedures will
12、be trained analysts capable of performing common laboratoryprocedures skillfully and safely. It is expected that work will beperformed in a properly equipped laboratory and that proper1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Relat
13、ed Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved June 10, 2003. Published August 2003. Originallypublished in 1993. Last previous edition approved in 1998 as E 156893 (1998).2Annual Book of ASTM S
14、tandards, Vol 15.01.3Annual Book of ASTM Standards, Vol 14.02.4Annual Book of ASTM Standards, Vol 03.05.5Discontinued; see Annual Book of ASTM Standards, Vol 03.05.6Annual Book of ASTM Standards, Vol 15.05.7Annual Book of ASTM Standards, Vol 03.06.8Global Engineering Documents, 15 Inverness Way East
15、, Englewood, Colorado80112.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.waste disposal procedures will be followed. Appropriate qual-ity control practices must be followed, such as those describedin Guide E 882.6. Interferences6.1
16、 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 Analytical Balance, capable of weighing to 0.1 g.7.2 A
17、ssay 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 and 155C.7.5 Fire Clay Crucible, 30-g sample capacity.7.6 Hot Plate, having variable temperature control, usedwith ventilation control for acid fu
18、mes.7.7 Jewelers Rolls, capable of flattening dor beads.7.8 Muffle Furnace, having air circulation with draft con-trols, capable of temperatures to 1100C, accurate to 6 10C,used with ventilation controls for lead fumes.7.9 Semi-Microbalance, capable of weighing to 0.01 mg.7.10 Roasting Dish, 15-g sa
19、mple 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 American Chemical Society,where such specifications are av
20、ailable.9Other 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)Add 100mL ammonium hydroxide to 1700 mL of H2O.8.3 BoraxNa2B4O7Sodium borate
21、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), 75g of silica (SiO2), and 30 g of baking flour.8.5 Lead Foil99.9 % minimum, with gold content lessthan 0.001 g/g.8.6 Litharge, PbOLead oxide po
22、wder, with gold contentless than 0.001 g/g.8.7 Silica, SiO2Silicon dioxide powder, with gold contentless than 0.001 g/g.8.8 Silver Foil99.9 % minimum, with gold content lessthan 0.001 g/g.8.9 Soda Ash,Na2CO3Sodium carbonate powder, withgold content less than 0.001 g/g.8.10 Strong Nitric Acid Parting
23、 Solution, HNO3(1 + 2)Add 330 mL nitric acid to 660 mL of H2O.8.11 Weak Nitric Acid Parting Solution, HNO3(1 + 4)Add200 mL nitric acid to 800 mL H2O.9. Hazards9.1 Refer to Practices E 50 for precautions to be observed inthis test method.9.2 Use care when handling hot crucibles and operatingfurnaces
24、in order to avoid personal injury by either burn orelectrical shock.9.3 Lead and litharge (PbO) are toxic materials and arevolatile at relatively low temperatures. Use accepted safetyprocedures to avoid inhalation, ingestion, or skin contact.9.4 Refer to Notes 2-4, Note 6, and Note 7.10. Sampling10.
25、1 Collect the sample in accordance 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 Method D 2867, toconstant weight at 150C. If the analysis of a particular parti
26、clesize range is desired, separate fractions in accordance with TestMethod 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 6 1.0 g, and record
27、 thetest sample weights.11. Procedure11.1 Ignition:11.1.1 Spread5gofsilica (SiO2) in the bottom of apreheated roasting dish.11.1.2 Transfer the test sample to the top of the silica bed inthe roasting dish.11.1.3 Ash at 650C in a muffle furnace in accordance withTest Method D 2866. Cool.11.2 Fusion:1
28、1.2.1 Transfer calcine and silica to a clay 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 of5goflitharge (PbO).11.2.3 Place the crucible in a muffle furnace at 1050C for1h.NOTE 1Draft may be required for the first 15 min
29、 of fusion to preventboil-over.NOTE 2Warning: Fire assay products produce toxic lead oxide fumeswhen heated. Use protective clothing, and work only in well-ventilatedareas.11.2.4 Remove the crucible from the muffle furnace andpour molten liquid into the assay mold carefully, makingcertain that all l
30、ead droplets are transferred to the mold.NOTE 3Warning: Rapidly cooling slag may eject flying glass. Useeye protection and cover the slag immediately after pouring.9“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of re
31、agents not listed bythe American Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”E156803211.2.5 After cooling, separate the lead metal from the slag.Form the lead metal into a cube using a hammer an
32、d metalplate.NOTE 4Warning: Lead slag is toxic; use protective equipment anddispose of waste properly.11.3 Cupellation:11.3.1 Preheat a cupel at 1000C for 10 min in a mufflefurnace. Reduce the muffle furnace temperature controller to940C.11.3.2 Place the lead buttons on the hot cupels and melt,witho
33、ut draft, as the temperature drops to 940C (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 5A row of empty cupels should be placed in the front of themuffle furnace fo
34、r temperature control of the draft.11.3.4 Vent the muffle furnace and remove the cupel fromthe furnace. Cool.NOTE 6Warning: Hot cupels emit lead fumes. Use proper ventila-tion.11.4 Inquartation:11.4.1 Carefully remove the dor bead from the cupel andweigh on the semimicrobalance to the nearest 0.01 m
35、g. Recordthe dor weight.NOTE 7Warning: Used cupels are toxic; use protective equipmentand 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 and silver foil in 10 g of lead foil.11.4.4 Repeat t
36、he 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 8The use of jewelers rolls is recommended for flattening largedor beads.11.5.2 Anneal the bead in the crucible at 650C in a mufflerfurnace or over a bunsen burn
37、er.11.5.3 Place the crucible on a hot plate at 95C and add 25mL of HNO3(1 + 4), preheated to 60 6 10C. Heat for 30 min.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 HNO3(1 + 2). Cool.11.5.6 Rinse with 25 mL of NH4OH (1 + 1
38、7) and five timeswith 25 mL H2O. 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 the steps given in 11.4.3-11.5.7, reweigh, andrecord the weig
39、ht.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/g in accordance with PracticeE 29.13. Precision and Bias13
40、.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 2.1013.2 BiasNo information concerning the bias of this testme
41、thod 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.NOTE 9The within-laboratory precision measures the maximum d
42、if-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 10This test method has been evaluated in accordance withPractice E
43、 173. The Reproducibility R2of Practice E 173 corresponds tothe Reproducibiloity 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 content10Support data have been filed at ASTM Internati
44、onal Headquarters. RequestRR:E01-1007.TABLE 1 Silver Additions for InquartationDor Weight Range,mgSilver Foil Weight Factor Appliedto the Dor Weight0.00 to 0.1 300.1 to 0.2 100.2 to 1.0 60.1 to 10.0 410.0 2.25TABLE 2 Interlaboratory PrecisionMaterialMeanAu, g/gR1; E173Au, g/gR2; E173Au, g/gStripped
45、carbon 108.2 5.4 7.6Fine carbon 347.8 17.6 17.6Loaded carbon 3983 99.5 243E1568033ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the v
46、alidity 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 reviewed every five years andif not revised, either reapproved or withdrawn. Your c
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48、ve 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).E1568034
