1、Designation: E 1600 07Standard Test Method forDetermination of Gold in Cyanide Solutions by AtomicAbsorption Spectrometry1This standard is issued under the fixed designation E 1600; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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 test method covers the determination of gold in oreprocessing cyanide solution in the range from 0.3
3、to 10.0g/mL of gold by direct aspiration into an atomic absorptionspectrophotometer.1.1.1 This test method may also be applied to cyanide leachsolutions from metallurgical evaluation procedures.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
4、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. Specific precau-tions are given in 8.3, 8.5, Section 9, and 10.4.1.1.2. Referenced Documents2.1 ASTM Standards:2D 1193 S
5、pecification for Reagent WaterD 1293 Test Methods for pH of WaterD 6888 Test Method for Available Cyanide with LigandDisplacement and Flow Injection Analysis (FIA) UtilizingGas Diffusion Separation and Amperometric DetectionD 7237 Test Method for Aquatic Free Cyanide with FlowInjection Analysis (FIA
6、) Utilizing Gas Diffusion Separa-tion and Amperometric DetectionE29 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 Termino
7、logy Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals3E 663 Practice for Flame Atomic Absorption Analysis3E 882 Guide for Accountability and Quality Control in theChemical Analysis L
8、aboratoryE 1024 Guide for Chemical Analysis of Metals and MetalBearing Ores by Flame Atomic Absorption Spectropho-tometry3E 1060 Practice for Interlaboratory Testing of Spectro-chemical Methods of Analysis3E 1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analy
9、tical Method3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Summary of Test Method4.1 The sample solution is collected and preserved withsodium hydroxide, if necessary, by careful adjustment of pH.The test solution is filtered and gold con
10、tent is determined byflame atomic absorption spectrophotometry.5. Significance and Use5.1 In primary metallurgical processes for gold bearing ores,gold is extracted with an alkaline cyanide solution. Metallur-gical accounting, process control, and ore evaluation proce-dures depend on accurate, preci
11、se, and prompt measurementsof the gold concentrations.5.2 This test method is a referee method for compliancewith compositional specifications for metal content. It isassumed that all who use this procedure will be trained analystscapable of performing common laboratory procedures skill-fully and sa
12、fely. It is expected that work will be performed ina properly equipped laboratory and that proper waste disposalprocedures will be followed. Follow appropriate quality con-trol practices such as those described in Guide E 882.1This test method is under the jurisdiction of ASTM Committee E01 onAnalyt
13、ical Chemistry for Metals, Ores and Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1994. Last previous edition approved in 2002 as E
14、 1600 02.2For referenced ASTM 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.1Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Interferences6.1 Elements normally found in ore processing cyanidesolutions do not interfere. Use of instrumental backgroundcorrection is required to compensate for nonspecific absorptioninterferences in the flame.7. Appara
16、tus7.1 Atomic Absorption Spectrophotometer, equipped withbackground correction and capable of measuring gold at the242.8-nm wavelength using an air and acetylene flame over alinear range from 0.3 to 10.0 g/mL gold.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in
17、 all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society weresuch specifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of suffic
18、ientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type I of Specification D 1193.8.3 Sodium CyanideSodium Hydroxide SolutionDissolve 10 g of s
19、odium hydroxide (NaOH) and 10 g ofsodium cyanide (NaCN) in 1 L of water. (WarningThepreparation, storage, use, and disposal of NaCN solutionsrequire special care and attention. Avoid any possibility ofinhalation, ingestion, or skin contact with the compound, itssolution, or its vapors. Work only in
20、a well-ventilated hood.Refer to Practices E50.)8.4 Gold Standard Solution AWeigh 1.000 g of gold metal(99.99 % min purity) and transfer to a 1-L beaker in a fumehood. Add 200 mL of water, 80 mL of HCl, and 50 mL ofHNO3(1 + 1). Boil gently to expel NOxfumes, cool, transfer toa 1-L volumetric flask, d
21、ilute to volume, and mix.8.4.1 A certified reference solution meeting these specifica-tions may also be used.8.5 Gold Calibration Solutions (0.5, 1.0, 2.0, 5.0, 10.0g/mL)In a fume hood, pipette 10 mL of gold standardSolution A into a 1-L volumetric flask containing 100 mL ofsodium cyanide-sodium hyd
22、roxide solution. Dilute to volumeand mix (10 g/mL). (WarningReaction of acid or chlorineand cyanide solutions releases toxic hydrogen cyanide orcyanogen chloride gases. Prepare in a fume hood.)8.5.1 Pipette 5, 10, 20, and 50 mL of the 10 g/mL goldcalibration solution into each of four 100-mLvolumetr
23、ic flasks,respectively. Add 10 mL of sodium cyanide-sodium hydroxidesolution, dilute to volume, and mix.8.6 Reference SolutionDilute 100 mL of sodium cyanide-sodium hydroxide solution to 1 L with water.9. Hazards9.1 For precautions to be observed in this method, refer toPractice E50.9.2 Hydrogen cya
24、nide and alkali cyanide are very toxicsubstances. Use an efficient fume hood. Cyanide must bedisposed of with care, avoiding contact with acid that releaseshydrogen cyanide gas. Oxidation of cyanide with chlorine orhypochlorite must be carried out at high pH (greater than 11) toprevent generation of
25、 toxic cyanogen chloride gas.10. Procedure10.1 Collect, store, and dispose of the sample in accordancewith Practices E50.10.2 Determine the pH of the solution immediately aftersampling in accordance with Test Method D 1293. If the pH ofthe sample is less than 10, adjust the pH with small additionsof
26、 solid sodium hydroxide, followed by mixing, until the pH isgreater than 10.10.3 Test SolutionsFilter two 50-mL portions of samplesolution through a coarse-porosity filter paper.10.4 Photometry:10.4.1 Follow the instrument manufacturers instructions toadjust the instrument for gold at 242.8 nm. Warm
27、 up theinstrument with background correction applied in accordancewith the manufacturers instructions. With the gold hollowcathode lamp in position, energized and stabilized, adjust thewavelength to maximize the energy response of the 242.8-nmline. Light the burner, allow it to reach thermal equilib
28、rium,and adjust the instrument to zero while aspirating water.10.4.1.1 The use of an air-acetylene, lean, blue flame andcaustic stabilized drain bottle is required. (WarningReactionof acid and cyanide solutions in the burner chamber drainbottle may release toxic hydrogen cyanide gas. Add an excessof
29、 sodium hydroxide to the drain bottle to maintain the pHabove 11.)10.4.2 Precision of MeasurementsUse Practice E 663 todetermine if the instrument precision is acceptable as follows:10.4.2.1 Calibrate the instrument in accordance with themanufacturers instructions in absorbance. Set the absorbanceto
30、 zero while aspirating the reference solution.10.4.2.2 Aspirate the calibration solutions in order of in-creasing concentration, and select a calibration solution in therange from 0.2 to 0.4 absorbance.10.4.2.3 Alternate readings on the selected calibration solu-tion and reference solution, and calc
31、ulate the standard devia-tion of the readings on the selected calibration solution usingaccepted statistical methods. Measure the standard deviation in4Reagent Chemical, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents no
32、tlisted by theAmerican Chemical Society, see Reagent CHemicals and Standards,byJoseph Rosin, D. Nostrand Co., Inc., New York, NY, and the United StatesPharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc.,(USPC), Rockville, MD.TABLE 1 Gold in Cyanide SolutionsStatistical Informat
33、ionSolutions Mean, Au, g/mLR1 (PracticeE 1060), Au,g/mLR2 (PracticeE 1060), Au,g/mL1, 4 2.19 0.10 0.182, 5 0.19 0.05 0.213, 6 0.96 0.02 0.057, 10 4.87 0.17 0.228, 11 5.97 0.27 0.699, 12 10.7 0.15 1.28E1600072this way at increased measurement integration times until arelatively constant value is achi
34、eved.10.4.2.4 If the standard deviation under these conditions isgreater than 1 % of the average absorbance, determine thecause of the variability (for example, deposits in the burner orclogged capillary), and take corrective action.10.4.2.5 If the minimum requirements are not met, do notuse the ins
35、trument with this test method until the requiredstability is obtained.10.4.2.6 Collect all instrumental measurements for the testmethod using the instrumental settings which gave the opti-mum precision of measurement on the selected calibrationsolution.10.4.3 Linearity of Instrument ResponseUse Prac
36、ticeE 663 to determine if the instrument response is acceptable asfollows:10.4.3.1 Record absorbance measurements for each of thecalibration solutions and the reference solution, prior to deter-mining samples.10.4.3.2 Adequate instrument response is obtained if thedifference between the 5-g/mL calib
37、ration solution and the10-g/mL calibration solution is sufficient to permit estimationof150 of the difference between them.10.4.3.3 Adequate linearity is confirmed if the slope of thecalibration curve between the 5 and 10-g/mL calibrationsolutions is at least 90 % of the slope between the references
38、olution and the 0.5-g/mL calibration solution.10.4.4 High-Precision Method:10.4.4.1 Calibrate the instrument in accordance with themanufacturers instructions in absorbance or gold concentra-tion.10.4.4.2 Adjust the instrument to zero with the referencesolution and measure the test sample solution to
39、 determine itsplace in the order of increasing concentration of the calibrationsolutions.10.4.4.3 Aspirate the test solution and the closely bracketingcalibration solutions in order of increasing absorbance orconcentration without intervening water aspirations. Repeatthree times and calculate the av
40、erage absorbance or concentra-tion value for each of the three solutions.10.4.5 Linear Curve Method:10.4.5.1 Calibrate the instrument in accordance with themanufacturers instructions in absorbance or gold concentra-tion.10.4.5.2 Record the reference solution and calibration solu-tion readings before
41、 and after each test sample solution,selecting a different calibration solution after each test solution.10.4.5.3 Continue recording measurements until at leastthree readings have been recorded for all test sample solutionsand at least one reading has been recorded for each calibrationsolution. Calc
42、ulate the average reading for each of the solu-tions.11. Calculation11.1 High-Precision MethodThe gold concentration ofthe test solution is calculated in accordance with Guide E 1024as follows:Ct5AtCh2 C1!Ah2 A1!(1)where:Ct= concentration of gold in the test solution, g/mL,Ch= concentration of gold
43、in the higher calibration solu-tion, g/mL,C1= concentration of gold in the lower calibration solu-tion, g/mL,At= average absorbance or concentration reading of thetest solution,Ah= average absorbance or concentration reading of thehigher calibration solution, andA1= average absorbance or concentrati
44、on of the lowercalibration solution.11.2 Linear Curve MethodCalculate the gold concentra-tion of each test sample solution in micrograms per millilitreusing the graphical method in accordance with Guide E 1024,by simple linear regression, or by an equivalent computermethod.11.3 Average the results o
45、f the duplicate test sample solu-tions and round the results to the nearest 0.1 g/mL inaccordance with Practice E29.12. Precision and Bias12.1 PrecisionAn interlaboratory study was undertaken totest the precision of this test method in accordance withPractice E 173 on six solutions in eight laborato
46、ries. Theresults from the study are summarized in Table 1. Since as fewas three laboratories returned results for some of the materials,Practice E 1060 was used to estimate the precision. The basedata and statistics are documented.5NOTE 1Solutions 1 through 6 were analyzed by more laboratoriesthan S
47、olutions 7 through 12.NOTE 2The reproducability, R2 of Practice E 1060 corresponds to thereproducability index, R, of Practice E 1601 and the repeatability, R1 ofPractice E 1060 corresponds to the repeatability index, r, of PracticeE 1601.12.1.1 RepeatabilityThe repeatability standard deviation(sw)
48、ranged from 0.01 to 0.12 g/mL gold over the range of thematerials tested. The R1 value in Table 1 for each of thematerials tested indicates the maximum difference expectedbetween results in a single laboratory at 95 % confidence.12.1.2 ReproducibilityThe reproducibility standard devia-tion (ssr) ran
49、ged from 0.01 to 0.15 g/mL gold over the rangeof the materials tested. The R2 value in Table 1 for each of thematerials tested indicates the maximum difference expectedbetween results in different laboratories at 95 % confidence.12.2 BiasNo information on the bias of this test method isknown. Accepted reference materials were not included in thematerials used in the interlaboratory study. Users of this testmethod are encouraged to employ accepted reference materi-als, if available, and to judge the bias of the test method fromthe differ
