1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58zinc Ion-exchange/EDTA titrimetric methodICS 73.060.99Zinc sulfide concentrates Determination of BR
2、ITISH STANDARDBS ISO 12739:2006BS ISO 12739:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2006 BSI 2006ISBN 0 580 48800 4request to its secretary.Cross-referencesThe British Standards which implement international publications r
3、eferred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online.This publication does not purport to include all the necessary pro
4、visions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 23 and a
5、 back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsA list of organizations represented on this committee can be obtained on present to the responsible international/European committee an
6、y enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.National forewordThis British Standard reproduces verbatim ISO 12739:2006 and implements it as the UK national standard. T
7、he UK participation in its preparation was entrusted to Technical Committee NFE/36, Copper, lead and zinc ores and concentrates, which has the responsibility to: aid enquirers to understand the text;INTERNATIONALSTANDARDISO12739Second edition2006-07-01Reference numberISO 12739:2006(E)Zinc sulfide co
8、ncentrates Determination of zinc Ion-exchange/EDTA titrimetric methodConcentrs sulfurs de zinc Dosage du zinc Mthode par change dions et titrage lEDTABS ISO 12739:2006iiiiiContents Page1 Scope 12 Normative references 13 Principle 14 Reagents . 15 Apparatus . 36 Sample 36.1 Test sample 36.2 Test port
9、ion 37 Procedure . 37.1 Number of determinations 37.2 Blank test . 47.3 Dissolution of test portion 47.4 Preparation of the ion-exchange column 47.5 Adsorption of zinc on ion-exchange column 57.6 Elution of zinc from ion-exchange column . 57.7 Titration 57.8 Determination of the titration factor of
10、the EDTA standard volumetric solution . 58 Expression of results 69 Precision . 79.1 Expression of precision 79.2 Procedure for obtaining the final result 79.3 Between-laboratories precision . 79.4 Check of trueness . 810 Test report 9Annex A (normative) Ion-exchange resins and columns . 10Annex B (
11、normative) Procedure for the preparation and determination of the mass of a predried test portion . 12Annex C (normative) Determination of cadmium by atomic absorption spectrometry . 14Annex D (normative) Flowchart of the procedure for the acceptance of analytical values for test samples . 16Annex E
12、 (informative) Effect of potentially interfering elements . 17Annex F (informative) Derivation of precision equations . 18Bibliography . 23BS ISO 12739:2006ivForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies(ISO member bodies). Th
13、e work of preparing International Standards is normally carried out through ISOtechnical committees. Each member body interested in a subject for which a technical committee has beenestablished has the right to be represented on that committee. International organizations, governmental andnon-govern
14、mental, in liaison with ISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The ma
15、in task of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies for voting. Publication as anInternational Standard requires approval by at least 75 % of the member bodies casting a vote.Atten
16、tion is drawn to the possibility that some of the elements of this document may be the subject of patentrights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 12739 was prepared by Technical Committee ISO/TC 183, Copper, lead, zinc and nickel ores andconcentrates
17、.This second edition cancels and replaces the first edition (ISO 12739:1997), which has been technicallyrevised.BS ISO 12739:20061Zinc sulfide concentrates Determination of zinc Ion-exchange/EDTA titrimetric methodWARNING This International Standard may involve hazardous materials, operations and eq
18、uipment.It is the responsibility of the user of this International Standard to establish appropriate health andsafety practices and determine the applicability of regulatory limitations prior to use.1ScopeThis International Standard specifies an ion-exchange/EDTA titrimetric method for the determina
19、tion of themass fraction of zinc in zinc concentrates. The method is applicable to zinc sulfide concentrates having a massfraction of zinc in the range from to .2 Normative referencesThe following referenced documents are indispensable for the application of this document. For datedreferences, only
20、the edition cited applies. For undated references, the latest edition of the referenced document(including any amendments) applies.ISO 385, Laboratory glassware BurettesISO 648, Laboratory glassware One-mark pipettesISO 1042, Laboratory glassware One-mark volumetric flasksISO 3696, Water for analyti
21、cal laboratory use Specification and test methodsISO 4787, Laboratory glassware Volumetric glassware Methods for use and testing of capacityISO 9599, Copper, lead and zinc sulfide concentrates Determination of hygroscopic moisture in the analysissample Gravimetric method3 PrincipleThe test portion o
22、f zinc concentrate is dissolved in hydrochloric, nitric and sulfuric acids. The acidity is adjustedto about with respect to hydrochloric acid. Zinc is adsorbed on a strongly basic anion-exchange resin.Some interfering ions are removed by elution with dilute hydrochloric acid. Zinc is eluted with ana
23、mmonia/ammonium chloride solution. Zinc is determined in the eluate by titration with EDTA at a pH ofapproximately 5,6 using xylenol-orange indicator.4ReagentsDuring the analysis, only reagents of recognized analytical grade and water that complies with grade 2 ofISO 3696 shall be used.4.1 Zinc, min
24、imum purity, free from oxide prior to use.11 % 62 %2 mol/l2 mol/l99,99 %BS ISO 12739:20062The surface of the metal may be cleaned by immersing the metal in hydrochloric acid (4.3) diluted , for, then washed well with water followed by an acetone rinse and dried in an oven at .4.2 Xylenol-orange indi
25、cator ()Mix of the sodium salt of xylenol orange with of potassium nitrate crystals by gently grinding in aceramic mortar with a pestle. Mixing is considered complete when the colour is uniform throughout.4.3 Hydrochloric acid ( to )4.4 Hydrochloric acid, diluted ( )Add of hydrochloric acid (4.3) to
26、 of water.4.5 Hydrochloric acid, diluted ( )Add of hydrochloric acid (4.3) to of water.4.6 Nitric acid ()4.7 Nitric acid, diluted ( )Add of nitric acid (4.6) to of water.4.8 Sulfuric acid, diluted ( )Add carefully and slowly, while stirring, of sulfuric acid ( ) to of water.4.9 Sulfuric acid, dilute
27、d ( )Add of dilute sulfuric acid (4.8) to of water.4.10 Hydrofluoric acid ( to )4.11 Ammonia solution, diluted ( )Add of aqueous ammonia solution ( ) to of water.4.12 Ammonia/ammonium chloride solutionDissolve of ammonium chloride in of dilute ammonia solution (4.11).4.13 Hydrochloric acid/ascorbic
28、acid solutionDissolve of ascorbic acid in of dilute hydrochloric acid (4.5). Prepare fresh on the day of use.4.14 Ammonium fluoride solution ()Dissolve of ammonium fluoride in water and dilute to .4.15 Sodium thiosulfate solution ()Dissolve of sodium thiosulfate pentahydrate in water and dilute to .
29、4.16 Buffer solution ()Dissolve of ammonium acetate and of concentrated acetic acid ( ) in water and diluteto .1 + 91 min 50C0,1 % m/m0,1 g 100 g201,16 g/ml 1,19 g/ml1 + 1500 ml 500 ml1 + 5100 ml 500 ml201,42 g/ml1 + 1500 ml 500 ml1 + 1500 ml 201,84 g/ml 500 ml1 + 10020 ml 1 000 ml201,13 g/ml 1,15 g
30、/ml7 + 10070 ml 200,89 g/ml 1 000 ml20 g 1l0,25 g 100 ml50 g/l50 g 1l100 g/l100 g 1lpH = 5,5250 g 25 ml 201,05 g/ml1lBS ISO 12739:200634.17 Para-nitrophenol indicator solution ()Dissolve of para-nitrophenol in water and dilute to .4.18 EDTA standard volumetric solution ()Dissolve of the di-sodium sa
31、lt of ethylenediaminetetraacetic acid dihydrate (EDTA) in water and dilute to.5 Apparatus5.1 Class A volumetric glassware complying with ISO 385, ISO 648 and ISO 1042, and used in accordancewith ISO 4787.5.2 Balance, capable of being read to .5.3 Laboratory hotplate5.4 Muffle furnace, capable of ope
32、rating at .5.5 Platinum crucibles, of capacity .5.6 Ion exchange columns, having typical dimensions as shown in Annex A.6Sample6.1 Test samplePrepare an air-equilibrated test sample in accordance with ISO 9599.NOTE A test sample is not required if predried test portions are to be used (see Annex B).
33、6.2 Test portionTaking multiple increments, extract a test portion of , weighed to the nearest , from the test sample,in such a manner that it is representative of the contents of the dish or tray. At the same time as the test portionis weighed, weigh test portions for the determination of hygroscop
34、ic moisture in accordance with ISO 9599.Alternatively, the method specified in Annex B may be used to prepare predried test portions directly from thelaboratory sample.7 Procedure7.1 Number of determinationsCarry out the determinations at least in duplicate, as far as possible under repeatability co
35、nditions, on each testsample.NOTE Repeatability conditions exist where mutually independent test results are obtained with the same method onidentical test material in the same laboratory, by the same operator using the same equipment, within short intervals of time.2 g/l0,2 g 100 ml0,1 mol/l37,2 g1
36、l0,1 mg800C25 ml0,5 g 0,1 mgBS ISO 12739:200647.2 Blank testDetermine a reagent blank. It is advisable to perform duplicate blank determinations every time an analysis iscarried out on a laboratory sample. The blank samples are carried through the whole procedure, apart fromwhere no laboratory sampl
37、e test portion is required. The volume of EDTA titrant used is .7.3 Dissolution of test portionPlace the test portion in a conical beaker. Add of hydrochloric acid (4.3). Cover with a watch glassand heat the beaker and contents gently for .Add of dilute nitric acid (4.7) and of dilute sulfuric acid
38、(4.8). Heat and evaporate the solution toabout . Cool and add, with caution, about of water and boil the solution.Cool the solution to room temperature and filter it into a beaker through a medium-speed cellulose filterpaper. Wash the beaker and filter paper thoroughly with dilute sulfuric acid (4.9
39、), collecting the washings in thesame beaker.If an acid-insoluble material is present, place the filter and insoluble residue in a platinum crucible (5.5) (see thelast five paragraphs of this subclause) and gently reduce the paper to ashes in the muffle furnace (5.4) at. Allow the crucible and resid
40、ue to cool to ambient temperature. Add of dilute sulfuric acid (4.8), of nitric acid (4.6) and of hydrofluoric acid (4.10) and evaporate the solution nearly to dryness. Cool andadd water in small quantities to dissolve the soluble salts. Filter through a medium-speed cellulose filter paperand add th
41、e filtrate and washing solution to the initial solution obtained above as described in paragraphs 1 to 3.Heat to evaporate the combined filtrates to a volume of to . Cool and add of hydrochloric acid(4.3). Dilute to with water.If the sample contains lead, damage to the platinum crucible may occur. I
42、n this case, acid-insoluble materialshould be treated as follows.Rinse the insoluble residues into a polytetrafluoroethylene beaker with a fine jet of water. Place the filter in aporcelain crucible and gently ash the paper in the muffle furnace at to . Allow the crucible to coolto ambient temperatur
43、e.Rinse the material from the crucible by washing with a small quantity of water into the polytetrafluoroethylenebeaker used above. Add of dilute sulfuric acid (4.8), of nitric acid (4.6) and of hydrofluoric acid(4.10), and evaporate the solution nearly to dryness.Cool and add water in small quantit
44、ies to dissolve the soluble salts. Filter through a medium-speed cellulosefilter paper and add the filtrate and washing solution to the initial solution obtained above.Should it be confirmed that the filter paper contains no zinc, the procedure of ashing the filter paper may beomitted.7.4 Preparatio
45、n of the ion-exchange columnExamples of ion-exchange columns that are suitable for use are shown in Annex A. Pack water-soaked cottonor glass-wool pads into the bottom of the column to a thickness of about . This will retain resin in thecolumn during use.Soak the resin overnight in distilled water t
46、o make a slurry. With the stopcock open, carefully transfer the slurryinto the column to form a settled bed. This resin bed is formed by about of the swollen resin. Close thestopcock and put about a thickness of water-soaked glass wool or cotton wool on top of the resin.It is essential to ensure tha
47、t the resin is covered by liquid at all times, because air trapped in a resin causes“channelling”, i.e. uneven flow rate and poor efficiency in the ion exchanger. If air enters the resin bed, it isrecommended that the column be emptied and then repacked.Vb300 ml 25 ml5 min20 ml 15 ml5ml 50 ml300 ml8
48、00C 2ml 2ml2ml60 ml 80 ml 16 ml100 ml600C 700C2ml 2ml 2ml5mm16 ml5mmBS ISO 12739:20065Pass about of hydrochloric acid (4.5) through the column ensuring that the resin is covered at all times.Adjust the flow rate to about using the stopcock control. The resin can be rapidly regenerated at anytime by
49、passing of water and then of dilute hydrochloric acid (4.5) through the column, ensuringthat the resin is always covered with liquid.7.5 Adsorption of zinc on ion-exchange columnQuantitatively transfer the test solution obtained in 7.3 to the ion-exchange column at a flow rate of about.Rinse the beaker with small increments of dilute hydrochloric acid (4.5) and transfer the washings to the column.A total washing volume of should be sufficient. Continue to drain the column until the l
