ISO INTERNATIONAL STANDARD 4694 First edition 1987-04-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXKAYHAPOAHAA OPrAHM3ALIMR O CTAHAAPTM3ALMM Ironores- Determinationoffluorinecontent- lon-selective electrode method Minerais de fer -Dosage du fluor - Methode par electrode selective Reference number ISO 4694: 1987 (E) Coovriaht International Oraanization for Standardizatior Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards 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 organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by least 75 % approval by the member bodies voting. International Standard ISO 4694 was prepared by Technical Committee ISO/TC 102, Iron ores. Users shoufd note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. ? International Organization for Standardization, 1987 Printed in Switzerland Coovriaht International Oraanization for Standardization ISO 4694:1987 (E) INTERNATIONALSTANDARD Iron ores -- Determination of fluorine content lon-selective electrode method 1 Scope and field of application 4.2 Sodium hydroxide, 300 g/l solution. This International Standard specifies an ion-selective electrode Dissolve 75 g of sodium hydroxide pellets in 250 ml of water. method for the determination of the fluorine content of iron ores. 4.3 Hydrochloric acid, 1,16 to 1,19g/ml, free from fluorine. This method is applicable to a concentration range of 0,005 to 1 % (m/m)1) of fluorine in natural iron ores, and iron ore con- 4.4 Hydrochloric acid, @ 1,16 to 1,19 g/m, diluted 1 + 2. centrates andagglomerates including sinterproducts. 4.5 Sodium citrate, buffer solution, c(Na3CgHs07-2H20) = 1 mol/l. 2 References In a 1 litre beaker dissolve 294,1g of tri-sodium citrate ISo 648, Laboratory glassware -- One-mark pipettes. dihydrate in about 800 m! of water. Adjust to pH 5,0 ± 0,1 with hydrochloric acid (4.4). 1So1042,Laboratory glassware- One-mark volumetric Transfer to a 1 litre volumetric flask and dilute to the mark with flasks. water. ISo3081,Ironores-Incrementsampling-Manualmethod. NOTE - Alternatively, in the case of tr-sodium citrate 5,5-hydrate, use 357,2 g. Iso 3082, Iron ores -- increment sampling and sample prepara- tion - Mechanical method. 4.6 Fluorine, standard solutions. Iso 3083, Iron ores - Preparation of samples - Manual All of the following solutions (4.6.1 to 4.6.5) shall be stored in method. plastics bottles. Iso7764, IronoresPreparationofpredriedtest samplesfor chemical analysis. 4.6.1 Standard solution A. Dry a suitable quantity of sodium fluoride at 105 °C. Dissolve 1,108 g of the dried sodium fluoride in water, transfer 3-Principle to a 1 litre volumetric flask and dilute to the mark with water. Fusion of a test portion in sodium hydroxide and dissolution in 1 ml of this standard solution contains 500 μg of fluorine. water and hydrochloric acid.Dry filtration followed by.direct potentiometricdetermination,usingafluorideion electrode in the presence of sodium citrate buffer. 4.6.2 Standard solution B. Pipette 100,0 ml of solution A into a 500 ml volumetric flask, and dilute to the mark with water. 4Reagents 1 ml of this standard solution contains 100 μg of fluorine. During the analysis,use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 4.6.3 Standard solut