ISO INTERNATIONAL STANDARD 7335 First edition 1987-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEKAYHAPOAHAA OPIAHM3ALMH NO CTAHAAPTM3AMM Iron ores - Determination of combined water content - Kari Fischer titrimetric method Minerais de fer - Dosage de I'eau de constitution - Methode titrimetrique de Karl Fischer Reference number ISO 7335: 1987 (E) No reproduction or networking pemited without license from IHS Not for Resale Foreword ISo (the International Organization for Standardization) is a wordwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carriedout throughiSotechnical 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 the ISo Council. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO7335 was prepared by Technical Committee ISO/TC 102, Iron ores. Users should 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 Copyrightlntematinal organizatin for Standardization No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONAL STANDARD ISO7335:1987 (E) Iron ores - Determination of combined water content - Karl Fischer titrimetric method Scope and field of application exhausted, it should be washed down the sink with a copious flow of water. This International Standard specifies a titrimetric method for thedetermination of the combinedwater content of ironores, 4.3Nitrogen.A supply of filtered, predried, oil-free nitrogen using Karl Fischer solution. containing less than 10 μl of oxygen per litre at a pressure of approximately 35 kPa above atmospheric pressure. This method is applicable to a concentration range of 0,05 to 10 % (m/m) of combined water in natural iron ores, and iron 4.4 Ethylene glycol (OHCH2·CH2OH)-methanol (CH3OH) ore concentrates and agglomerates including sinter products. mixture (1 + 1). This mixture should be tested each time before use for the amount of free moisture it contains. If it contains NOTE-The term"combined water"means that part of the water more than 0,05 % (m/m) of free moisture, it shall not be used. content of an iron ore that can be removed only at temperatures substantially higher than 100 to 110 oC. NOTE- Inplace of this mixture,anhydrous ethylene glycol maybe used. In this case, Karl Fischer solution must contain the appropriate amount of methanol. 2 References 4.5KarlFischersolution(2,5to3,0mgHO/ml).Thissolu Iso385,Laboratoryglassware-Burettes. tion shall be standardized ontheday of use by one of the following substances: Iso 3081, Iron ores - Increment sampling - Manual method. a)a standard watermethanol solution;this solutionshall Iso 3082, Iron ores - Increment sampling and sample prepara- previously be standardized by use of the following b), c) tion - Mechanical method. : (p JO b) water added by means of a microsyringe; Iso 3083, Iron ores -- Preparation of samples - Manual method. c) citric acid monohydrate [C(OH)(COOH)(CH2COOH)2·H2O]; ISo 7764, Iron ores - Preparation of predried test samples for chemical analysis. d) disodium tartrate dihydrate [(CHOH·COONa)2·2H2O]. 5 Apparatus 3Principle A suitable apparatus for the determination is illustrated in figure Liberation of adventitious hygroscopic moisture by heating the 1 (two-furn