1、Designation: D7728 11Standard Guide forSelection of ASTM Analytical Methods for Implementation ofInternational Cyanide Management Code Guidance1This standard is issued under the fixed designation D7728; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 guide is applicable for the selection of appropriateASTM standard analytical meth
3、ods for metallurgical process-ing sites to conform to International Cyanide ManagementCode guidance for the analysis of cyanide bearing solutions.1.2 The analytical methods in this practice are recom-mended for the sampling preservation and analysis of totalcyanide, available cyanide, weak acid diss
4、ociable cyanide, andfree cyanide by Test Methods D2036, D4282, D4374, D6888,D6994, D7237, D7284, and D7511. The values stated in SIunits are to be regarded as standard. No other units ofmeasurement are included in this standard.1.3 This guide does not purport to address all of the safetyconcerns, if
5、 any, associated with its use. It is the responsibilityof the user of this standard guide to establish appropriatesafety and health practices and determine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Spec
6、ification for Reagent WaterD1293 Test Methods for pH of WaterD1976 Test Method for Elements in Water by Inductively-Coupled Argon Plasma Atomic Emission SpectroscopyD2036 Test Methods for Cyanides in WaterD3694 Practices for Preparation of Sample Containers andfor Preservation of Organic Constituent
7、sD3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD4282 Test Method for Determination of Free Cyanide inWater and Wastewater by MicrodiffusionD4374 Test Methods for Cyanides in WaterAutomatedMethods for Total Cyanide, Weak Acid Dissociable Cya-nide,
8、 and ThiocyanateD4840 Guide for Sample Chain-of-Custody ProceduresD4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD6888 Test Method for Ava
9、ilable Cyanide with LigandDisplacement and Flow Injection Analysis (FIA) UtilizingGas Diffusion Separation and Amperometric DetectionD6994 Test Method for Determination of Metal CyanideComplexes in Wastewater, Surface Water, Groundwaterand Drinking Water Using Anion Exchange Chromatogra-phy with UV
10、DetectionD6696 Guide for Understanding Cyanide SpeciesD7237 Test Method for Free Cyanide with Flow InjectionAnalysis (FIA) Utilizing Gas Diffusion Separation andAmperometric DetectionD7284 Test Method for Total Cyanide in Water by MicroDistillation followed by Flow Injection Analysis with GasDiffusi
11、on Separation and Amperometric DetectionD7365 Practice for Sampling, Preservation and MitigatingInterferences in Water Samples for Analysis of CyanideD7511 Test Method for Total Cyanide by Segmented FlowInjection Analysis, In-Line Ultraviolet Digestion and Am-perometric DetectionD7572 Guide for Reco
12、very of Aqueous Cyanides by Ex-traction from Mine Rock and Soil After Remediation ofProcess Releases3. Terminology3.1 Definitions:For definitions of terms used in this practice, refer toTerminology D1129 and Guide D6696.3.2 Definitions of Terms Specific to This Standard:3.2.1 refrigeration, nstoring
13、 the sample between its freez-ing point and 6C.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.06 on Methods for Analysis forOrganic Substances in Water.Current edition approved Sept. 1, 2011. Published September 2011. DOI:1
14、0.1520/D7728112For 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.1Copyright ASTM International, 100 Barr Harbor
15、Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 weak and dissociable (WAD) cyanide, navailablecyanide and weak acid dissociable cyanides, excluding deter-mination of iron-, gold-, and cobalt- cyanide complexes.3.2.3 titratable cyanide, ncyanide measured by titrationwith sil
16、ver nitrate to a rhodanine or silver electrode end point.4. Summary of Guide4.1 Guidance is provided for selection of the appropriateanalytical methods to determine cyanide for to apply to theInternational Cyanide Management Code guidance for analysisof cyanide in solution.5. Significance and Use5.1
17、 This guide is intended as a means for selecting theproper methods for measuring cyanide to conform to theInternational Cyanide Management Code guidance related tothe analysis of cyanide bearing solutions. Cyanide is analyzedin process solutions and in discharges in order to apply codeguidance; howe
18、ver, improper sample collection and preserva-tion can result in significant positive or negative bias, poten-tially resulting in over reporting or under reporting cyanidereleases into the environment.5.2 This guide contains comparative test methods that areintended for use in routine monitoring of c
19、yanide. It is assumedthat all who use methods listed in this guide will be trainedanalysts capable of performing them skillfully and safely. It isexpected that work will be performed in a properly equippedlaboratory applying appropriate quality control practices suchas those described in Guide D3856
20、.6. Interferences6.1 Multiple interferences could affect the cyanide analyti-cal results using methods enumerated in this guide. Refer toPractice D7365 for proper handling of the solutions duringsampling, mitigation of interferences and preservation prior tocyanide analysis.6.2 Unless otherwise spec
21、ified, samples must be analyzedwithin 14 days; however, it is recommended to estimate theactual holding time for each new sample matrix as described inPractice D4841. Certain sample matrices may require imme-diate analysis to avoid cyanide degradation due to interfer-ences. A holding time study is r
22、equired if there is evidence thatcyanide degradation occurs from interferences which wouldcause the holding time to be less than specified in this practiceor Practice D7365. Potential interferences for cyanide analyti-cal methods are shown in Table 1.7. Reagents and Materials7.1 Purity of ReagentsRe
23、agent grade chemicals shall beused in this guide. Unless otherwise indicated, it is intendedthat all reagents shall conform to the specifications of theCommittee on Analytical Reagents of the American ChemicalSociety, where such specifications are available. Other gradesmay be used, provided it is f
24、irst ascertained that the reagent isof sufficiently high purity to permit its use without lesseningthe accuracy of the determination.37.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water that meetsthe purity specifications of Type I or Type II w
25、ater, presentedin D1193. Type III or IV water may be used if they do not causemeasurable change in the blank or sample.7.3 Sample BottlesSee section 9.2 for further informationabout sample bottles.8. Hazards8.1 WarningBecause of the toxicity of cyanide, greatcare must be exercised in its handling. A
26、cidification of cyanidesolutions produces toxic hydrocyanic acid (HCN). Adequateventilation is necessary when handling cyanide solutions and afume hood should be utilized whenever possible.8.2 WarningMany of the reagents used in this guide arehighly toxic. These reagents and their solutions and extr
27、actedsolids must be disposed of properly.9. Sampling9.1 Obtain a representative sample of the solution to betested by using, where available, ASTM sampling methodsdeveloped for the cyanide processing industry (see PracticeD7365.9.2 Sampling methodology for materials of similar physicalform shall be
28、used where no specific methods are available.9.3 Laboratory personnel and field samplers should followthe industry best practice or acceptable metallurgical methodsfor sampling and sample preparation of process solutions.9.3.1 Refer to Guide D4840 for chain-of-custody proce-dures.9.4 Sample Containe
29、rs:9.4.1 Sample containers shall be made of materials that willnot contaminate the sample and bottles need to be cleanedthoroughly to remove all extraneous surface contaminationprior to use, if necessary. Chemically resistant rigid plasticcontainers, such as those made of high-density polyethylene(H
30、DPE) are suitable as well as amber glass containers.Samples should be collected and stored in opaque containers tominimize exposure to ultraviolet radiation and loss of moistureand hydrogen cyanide.9.5 New, commercially cleaned, containers certified to befree of contamination are recommended for han
31、dling solutions;otherwise, wash containers with soap or biodegradable deter-gent if required, then dry by draining. For further informationon sample containers, see Practices D3694.10. Procedure Selection10.1 Principles, Standards of Practice and Guidance10.1.1 The International Cyanide Management C
32、ode isorganized into principles and standards of practice for imple-mentation using the guidance. Those principles, standards of3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the America
33、n Chemical Society, see Analar Standards for LaboratoryChemicals, (http:/), and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7728 112practice and guidance related to metallurgical processingwhich require the use of analytical method
34、s are discussed withidentification of specific ASTM analytical methods that areappropriate for implementing the guidance.10.2 Principle- Operations10.2.1 Manage cyanide process solutions and waste streamsto protect human health and the environment.10.2.1.1 Standard of Practice Introduce management a
35、ndoperating systems to minimize cyanide use, thereby limitingconcentrations of cyanide in mill tailings.10.2.1.2 Guidance - While facilities must use the amount ofcyanide determined to be metallurgically necessary for efficientprecious metal extraction, operations should use bottle roll orother test
36、 procedures to determine the optimal amount ofcyanide, and should re-evaluate and adjust addition rates asnecessary when changes in ore type or processing plantpractices occur. A summary of ASTM methods is given inTable 2.(1) Titratable cyanide Most metallurgical operations andlaboratories rely on t
37、he silver nitrate titration to estimate thecyanide available for leaching gold, which is standardized inthe D2036 Titration Procedure. Measurement units are typi-cally expressed as sodium cyanide, rather than cyanide, inorder to track the usage of the commercially available reagent.The solution pH s
38、hould be adjusted to about 12 prior toTABLE 1 Summary of CN Method Interferences - adapted from ASTM D7365-09ANALYSIS STEP COMPOUND PROCESS/MEASUREMENTTECHNIQUEDESCRIPTION OFINTERFERENCESampling,Preservation,and StorageResidual chlorine,peroxide, or other oxidizersN/A React with cyanide in solution
39、rapidlydecreasing the cyanide concentration. Oxidizers can co-existwith cyanideChloramines N/A React with sample at pH10 increasing or decreasing thecyanide concentrationSulfide N/A Reacts with cyanide and oxygen to form thiocyanate decreasingthe cyanide concentration. Reaction is especially rapid i
40、f metalsulfides are present.Native sulfur (colloidalsulfur)N/A Very rapid reaction to form thiocyanate. Decreases the cyanideconcentration.Sulfite N/A Reacts with cyanide at pH.10 decreasing the cyanideconcentration.Reaction is almost immediate at pH.12Light ( 50 mg S/L)GD-Amperometry Detected as Cy
41、anide (at 50 mg S/L)Thiocyanate Colorimetry Detected as CyanideFatty acids Titration Mask endpointSulfur dioxide Colorimetry Increase chloramine T demand resulting in negative bias. Theincreaseddemand may not be noticed in automated colorimetric methodsCarbonates GD-Amperometry Negative bias at 1500
42、 mg CO3/LD7728 113titration to assure that the all of the free cyanide is present asthe cyanide ion, rather than hydrogen cyanide.(2) Other techniques that may be used to directly estimatethe cyanide in process and laboratory solutions are ion selec-tive electrode (ISE), the ion chromatography (IC),
43、 and the freecyanide method in D7237. Users of these techniques will likelyneed to dilute process samples into the linear range of themethod and need to take into account any shifts in equilibriumof metal cyanide complexes resulting from dilution in inter-preting the results. Ion Chromatography and
44、Ion SelectiveElectrode ASTM methods have only been interlaboratoryvalidated for use in D2036 distillates. There are no ASTM IonChromatography, or Ion Selective Electrode methods that havebeen interlaboratory validated in complex hydrometallurgicalprocess matrices. The free cyanide method, D7237, has
45、 beeninterlaboratory tested for discharge waters, covering the rangeof 0.002 to 0.5 mg/L cyanide, with a lower scope limit of 0.009mg/L free cyanide in a chlorinated gold processing dischargematrix.(3) Convert results to kg NaCN/tonne of solution bymultiplying the cyanide result by 0.0019 and to lbs
46、 NaCN/tonne of solution by multiplying the cyanide result by 0.0038.(4) WAD cyanide methods Significant quantities of metalcyanide complexes in process solutions (i.e. Cu50 mg/L)make it difficult to detect the endpoint for the titratable cyanidemethod. In these cases, it is recommended to determine
47、theWAD cyanide using D 6888 and measure the metals that formcyanide complexes by method D1976 or method D6994.Todetermine the cyanide concentrations available for gold leach-ing, cyanide associated with certain metals (e.g. Cu, Ni, Hg,etc.) should be subtracted from the WAD cyanide values.10.2.1.3 S
48、tandard of Practice Implement measures toprotect birds, other wildlife and livestock from adverse effectsof cyanide process solutions.(1) Guidance - Process solutions impounded in a TailingStorage Facility (TSF), leaching facilities and solution pondscan attract birds, wildlife and livestock. An aqu
49、eus concentra-tion of 50 mg/L WAD cyanide or lower is typically viewed asbeing protective of most wildlife and livestock mortality otherthan aquatic organisms.(2) WAD cyanide methods Method D6888 is recom-mended for monitoring process solutions. D2036 test methodC, or D4374 WAD may also be used if demonstrated that theyproduce comparable results.10.2.1.4 Standard of Practice Implement measures toprotect fish and wildlife from direct and indirect discharges ofcyanide process solutions to surface water.(1) Guidance - Discharges to surface waters should
