312 International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION+MEXAYHAPOAHAH OPrAHM3ALMH TIO CTAHAAPTW3AUMM-ORGANISATION INTERNATIONALE DE NORMALISATION Manganese ores --- Determination of active oxygen content, expressed as manganese dioxide Titrimetric method Minerais de manganese -- Dosage de I'oxygene actif, exprime en dioxyde de manganese -- Methode titrimetrique Third edition - 1986-06-01 UDC 543.24 : 669.74 : 543.844 Ref. No. 1SO 312-1986 (E) (3) D 312-1986 Descriptors : minerals and ores, manganese ores, chemical analysis, determination of content, oxygen, volumetric analysis. Copyright International Organization for Standardization Price based on 2 pages Not for Resale 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 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 ISO 312 was prepared by Technical Committee ISO/TC 65, Manganeseandchromiumores. This third edition cancels and replaces the second edition (IS0 312-1980), of which it constitutes a minor revision. 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, 1986 Printed in Switzerland d without license from IHS Not for Resale ISO 312-1986 (E) INTERNATIONAL STANDARD Manganese ores --- Determination of active oxygen content, expressed as manganese dioxide - Titrimetric method 1 Scope and field of application 4.3.2 Standardization of the solution This International Standard specifies a titrimetric method, by Take three test portions from a standard sample of manganese reduction with ammonium iron(ll) suifate, for the determination ore having a known manganese dioxide content approximately of the active oxygen content (conventionally expressed as the same as that of the sample to be analysed and pass them manganese dioxide) of manganese ores. through all stages of the analysis (7.4). The titre of the potassium dichromate solution is given by the References 2 formula Iso 4296/1, Manganese ores - Sampling - Part 1: Increment B×m sampling. V × 100 IsO 4296/2, Manganese ores -- Sampling - Part 2: Prepara- tion of samples. where Iso 4297, Manganese ores and concentrates - Methods of T is the titre of the potassium dichromate solution, ex- chemicalanalysis - General instructions. pressed as grams of manganese dioxide corresponding to 1 mi of the solution; Principle 3 B is the manganese dioxide content, as a percentage by mass, of the standard sample of manganese ore; Dissolution of a test portion in an excess of a standard solution of ammonium iron(ll) suifate in sulfuric acid, to reduce the m is the mass, in grams, of the test portion from the stan- manganese dioxide present in the test portion. Back-titration of dard sample; the excess of ammonium iron(ll) sulfate with standard V is the volume, in millitres, of potassium dichromate volumetric potassium dichromate solution in the presence of solution used. sodium diphenylamine sulfonate as indicator. Take as the titre the average of the three results. Reagents 4 4.4 Sodium diphenylamine sulfonate, 0,8 g/l solution. Phosphoric acid, @ 1,7 g/ml. 4.1 Dissolve 0,8 g of powdered sodium diphenylamine sulfonate (CoHsNHCgHa.SONa) in a small volume of water and dilute 4.2 Ammonium