1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58zinc Solvent extraction and EDTA titrimetric methodICS 73.060.99Zinc sulfide concentrates Determina
2、tion of BRITISH STANDARDBS ISO 13291:2006BS ISO 13291:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2006 BSI 2006ISBN 0 580 48902 7request to its secretary.Cross-referencesThe British Standards which implement international publ
3、ications referred 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 nec
4、essary provisions 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 t
5、o 18, an inside back cover and a 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 int
6、ernational/European committee any 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 13291:2006 and implements i
7、t as the UK national standard. The 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;Reference numberISO 13291:2006(E)INTERNATIONAL STANDARD ISO13291Secon
8、d edition2006-06-15Zinc sulfide concentrates Determination of zinc Solvent extraction and EDTA titrimetric method BS ISO 13291:2006ii iiiContents Page Foreword iv 1 Scope . 1 2 Normative references . 1 3 Principle. 1 4 Reagents 2 5 Apparatus 3 6 Sample . 3 6.1 Test sample . 3 6.2 Test portion . 3 7
9、Procedure 3 7.1 Number of determinations . 3 7.2 Blank test. 4 7.3 Dissolution of test portion . 4 7.4 Extraction 4 7.5 Titration 4 7.6 Determination of the titration factor of the EDTA standard solution 5 8 Expression of results . 5 9 Precision 6 9.1 Expression of precision . 6 9.2 Procedure for ob
10、taining the final result . 6 9.3 Between-laboratories precision 6 9.4 Check of trueness. 7 10 Test report . 8 Annex A (normative) Procedure for the preparation and determination of the mass of a predried test portion 9 Annex B (normative) Flowchart of the procedure for the acceptance of analytical v
11、alues for test samples 11 Annex C (normative) Elements that interfere with this method 12 Annex D (informative) Derivation of precision equations 13 Bibliography . 18 BS ISO 13291:2006iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards
12、 bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organiza
13、tions, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in t
14、he ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of
15、 the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 13291 was prepared by Technical Committee ISO/TC 183, Copper,
16、lead, zinc and nickel ores and concentrates. This second edition cancels and replaces the first edition (ISO 13291:1997), which has been technically revised. BS ISO 13291:20061Zinc sulfide concentrates Determination of zinc Solvent extraction and EDTA titrimetric method WARNING This International St
17、andard may involve hazardous materials, operations and equipment. It is the responsibility of the user of this International Standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. 1 Scope This International Standard speci
18、fies a solvent extraction/titrimetric method for the determination of the mass fraction of zinc in zinc sulfide concentrates. The method is applicable to zinc sulfide concentrates having a mass fraction of zinc in the range from 11 % to 62 %. 2 Normative references The following referenced documents
19、 are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 385, Laboratory glassware Burettes ISO 648, Laboratory glassware One-mark pipet
20、tes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3696, Water for analytical laboratory use Specification and test methods ISO 4787, Laboratory glassware Volumetric glassware Methods for use and testing of capacity ISO 9599, Copper, lead and zinc sulfide concentrates Determination of
21、 hygroscopic moisture in the analysis sample Gravimetric method ISO Guide 35, Reference materials General and statistical principles for certification 3 Principle A test portion of zinc concentrate is dissolved in bromine and nitric acid. Any remaining insoluble residue is dissolved in sulfuric, nit
22、ric and hydrofluoric acids. A zinc thiocyanate complex is selectively extracted into methyl isobutyl ketone, after screening of some elements with thiourea and citrate ions. Partially extracted cadmium is screened with iodide ions before the final titration as explained in Annex C. Cobalt is extract
23、ed and determined separately, if present at concentration levels exceeding 0,05 %. Zinc is determined by titration with EDTA solution at pH 5,5. BS ISO 13291:20062 4 Reagents During the analysis, only reagents of recognized analytical grade and water that complies with grade 2 of ISO 3696 shall be u
24、sed. 4.1 Zinc metal, minimum purity 99,99 %, free from oxide prior to use. The surface of the metal may be cleaned by immersing the metal in hydrochloric acid (4.2), diluted 1 + 9 for 1 min, then washing well with water, followed by an acetone rinse and drying in an oven at 50 C. 4.2 Hydrochloric ac
25、id, (201,16 g/ml to 1,19 g/ml). 4.3 Bromine. 4.4 Nitric acid, (201,42 g/ml). 4.5 Hydrofluoric acid, (201,13 g/ml to 1,15 g/ml). 4.6 Hydrochloric acid, (201,16 g/ml to 1,19 g/ml) diluted (1 + 4). Add 200 ml of hydrochloric acid (4.2) to 800 ml of water. 4.7 Sulfuric acid, diluted (1 + 1). Add careful
26、ly and slowly, with stirring, 500 ml of sulfuric acid (201,84 g/ml) to 500 ml of water. 4.8 Ammonia, (200,89 g/ml). 4.9 4-methyl-2-pentanone (methyl isobutyl ketone). 4.10 Ethanol, pure or denatured. 4.11 Screening solution. Dissolve 60 g of thiourea, 100 g of di-ammonium citrate and 200 g of ammoni
27、um thiocyanate in water and dilute to 1 l. Filter if necessary. 4.12 Sodium fluoride solution (20 g/l). Dissolve 20 g of sodium fluoride in water. Dilute to 1 l. 4.13 Thiourea solution (100 g/l). Dissolve 100 g of thiourea in water and dilute to 1 l. 4.14 Buffer solution. Dissolve 250 g of hexamethy
28、lenetetramine in water. Add 60 ml of acetic acid (201,05 g/ml) and dilute to 1 l. 4.15 EDTA standard volumetric solution (0,05 mol/l). Dissolve 18,6 g of the di-sodium salt of ethylenediaminetetraacetic acid dihydrate (EDTA) in water. Dilute to 1 l. 4.16 Potassium iodide solution (1 000 g/l). Dissol
29、ve 100 g of potassium iodide in water and dilute to 100 ml. Prepare fresh on the day of use. BS ISO 13291:200634.17 Xylenol orange indicator (1 % m/m). Mix 1 g of the sodium salt of xylenol orange with 99 g of potassium nitrate crystals, by gently grinding in a ceramic mortar with a pestle. Mixing i
30、s considered complete when the colour is uniform throughout. 4.18 Iron stock solution. Dissolve 45 g of iron(III) nitrate nonahydrate Fe(NO3)39H2O in water and dilute to 1 l. 5 Apparatus Ordinary laboratory equipment and the following. 5.1 Volumetric glassware, of class A complying with ISO 385, ISO
31、 648 and ISO 1042 and used in accordance with ISO 4787. 5.2 Platinum crucibles, of 25 ml capacity. 5.3 Balance, capable of being read to 0,1 mg. 5.4 Oven, with its temperature controlled at 105 C 5 C. 5.5 Muffle furnace, having a maximum required operating temperature higher than 800 C. 5.6 Laborato
32、ry hotplate. 6 Sample 6.1 Test sample Prepare 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 A). 6.2 Test portion Taking multiple increments, extract a test portion from the test sample in such a man
33、ner that it is representative of the dish or tray. Weigh, to the nearest 0,1 mg, 2,5 g of test sample. At the same time as the test portion is weighed, weigh test portions for the determination of hygroscopic moisture in accordance with ISO 9599. Alternatively, the method specified in Annex A may be
34、 used to prepare predried test portions directly from the laboratory sample. 7 Procedure 7.1 Number of determinations Carry out the determinations at least in duplicate, as far as possible under repeatability conditions, on each test sample. NOTE Repeatability conditions exist where mutually indepen
35、dent test results are obtained with the same method on identical test material in the same laboratory by the same operator, using the same equipment within short intervals of time. BS ISO 13291:20064 7.2 Blank test Determine a reagent blank. It is advisable to perform duplicate blank determinations
36、every time an analysis is carried out on a laboratory sample. The blank samples are carried through the whole procedure, apart from where no laboratory-sample test portion is required. However, 5 ml of iron stock solution (4.18) should be added to assist in the determination of turbidity. The volume
37、 of EDTA titrant used is Vb. 7.3 Dissolution of test portion Place the test portion in a 300 ml narrow-necked conical flask. Moisten the material with about 20 ml of water and add 2 ml to 3 ml of bromine (4.3). Allow to react at ambient temperature for 15 min, swirling the flask and contents from ti
38、me to time. Add 15 ml of nitric acid (4.4) and leave for a further 15 min. Place the flask on a hotplate (5.6) and bring gently to the boil, to expel all bromine vapours. Cool, add 100 ml of water, heat to boiling and cool. If no insoluble material is present, transfer the liquid to a 500 ml one-mar
39、k volumetric flask, rinsing the conical flask thoroughly. Make up to the mark with water. If insoluble residue is present, filter through a medium-speed cellulose filter paper into a 500 ml one-mark volumetric flask. Rinse the filter thoroughly with water. Place the filter and insoluble residue in a
40、 platinum crucible (5.2) and gently ash in the muffle furnace (5.5) set at 800 C. Add 2 ml of dilute sulfuric acid (4.7), 2 ml of nitric acid (4.4) and 2 ml of hydrofluoric acid (4.5) and evaporate the solution nearly to dryness. Cool and add water in small quantities, to dissolve the soluble salts.
41、 Filter through a medium-speed cellulose filter paper and add the filtrate and washing solution to the 500 ml one-mark volumetric flask used above. Make up to the mark with water. If the sample contains lead, damage to the platinum crucible may occur. In this case, insoluble material should be treat
42、ed as follows. Rinse the insoluble residue into a polytetrafluoroethylene beaker with a fine jet of water. Place the filter in a porcelain crucible and gently ash the paper in the muffle furnace (5.5) at 600 C to 700 C. Allow the crucible to cool to ambient temperature. Rinse the material in the cru
43、cible by washing with a small quantity of water into the polytetrafluroethylene beaker used above. Add 2 ml of dilute sulfuric acid (4.7), 2 ml of nitric acid (4.4) and 2 ml of hydrofluoric acid (4.5) and evaporate the solution nearly to dryness. Cool and add water in small quantities, to dissolve t
44、he soluble salts. Filter through a medium-speed cellulose filter paper and add the filtrate and washing solution to the 500 ml one-mark volumetric flask used above. Make up to the mark with water. Should it be confirmed that the filter paper contains no zinc, the procedure of ashing the filter may b
45、e omitted. 7.4 Extraction Pipette 50,00 ml of the solution obtained in 7.3 into a 250 ml separating funnel. Add ammonia (4.8) dropwise until a slight turbidity develops. Add 5 ml of dilute hydrochloric acid (4.6) and 50 ml of screening solution (4.11). Mix well. Add 80 ml of 4-methyl-2-pentanone (4.
46、9) and shake for 1 min. Allow the phases to separate and slowly transfer the lower aqueous phase to another separating funnel. Perform a second extraction with 20 ml of 4-methyl-2-pentanone (4.9). Separate the phases and discard the aqueous phase. Combine the two separate organic phases in a 400 ml
47、low-form beaker. Place 1 ml of dilute hydrochloric acid (4.6) and 70 ml of ethanol (4.10) in each of the two separating funnels. Shake well and discharge the contents from both funnels into the 400 ml low-form beaker. 7.5 Titration Add, successively, 10 ml of sodium fluoride solution (4.12), 10 ml o
48、f thiourea solution (4.13), 20 ml of buffer solution (4.14), 5 ml of potassium iodide solution (4.16) and 0,1 g of xylenol orange indicator (4.17). Titrate with EDTA solution (4.15) until the colour changes from red to yellow. Titrate very slowly when approaching the equivalence point. Note the volu
49、me, Vt, of titrant used. BS ISO 13291:200657.6 Determination of the titration factor of the EDTA standard solution NOTE In order to obtain a relative accuracy of between 0,1 % and 0,2 %, it is necessary to standardize the EDTA solution with zinc at the same time and under the same conditions as the analysis. It is thus advisable for the calibration to follow the complete set of operating conditions set down for the analysis. Likewise, to improve the repeatability of the calibration, it is useful to p
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