6629 OSL) International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAR OPrAHV3ALMH HO CTAHAAPTM3ALMW-ORGANISATION INTE RNATIONALE DE NORMALISATION Chromium ores and concentrates -- Methods of chemical analysis --- General instructions Minerais et concentres de chrome - Methodes d'analyse chimique -- Instructions generales First edition - 1981-04-15 UDC 553.32 : 543 Ref. No. ISO 6629-1981 (E) ISO 6629-1981 (E) Descriptors : chromium minerals, chemical analysis, instructions. Price based on 2 pages Not for Resale Foreword Iso (the International Organization for Standardization) is a worldwide federation of national Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental 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. International Standard ISO 6629 was developed by Technical Committee ISO/TC 65, Manganese and chromium ores, and was circulated to the member bodies in February 1980. Australia France Poland Austria Hungary Portugal Buigaria India Romania China Italy South Africa, Rep. of Czechoslovakia Japan United Kingdom Egypt, Arab Rep. of Korea, Dem. P. Rep. of USSR No member body expressed disapproval of the document. International Organization for Standardization, 1981 ? Printed in Switzerland d without license from IHS Not for Resale ISO 6629-1981 (E) INTERNATIONAL STANDARD Chromium ores and concentrates - Methods of chemical analvsis --- General instructions Scope and field of application 3.1.6 The concentrations of solutions are expressed in one of 1 the following forms : This International Standard gives general instructions concern a) % (m/m), meaning the mass, in grams, of component ing the methods of chemical analysis of chromium ores and in 100 g of solution; concentrates. b) g/l, meaning the number of grams of component in 2 Reference 1 litre of solution; ISo 6129, Chromium ores -- Determination of hygroscopic c) % (V/V), meaning the volume, in mililitres, of compo- moisture content in analytical samples - Gravimetric nent in 100 ml of solution; method.1) d) mol/l, meaning the amount-of-substance concentra- tions with the unit mole per cubic decimetre (mol/dm3) or 3 General instructions mole per litre (mol/l). 3.1 Reagents 3.1.7 In each run, the standardization of a standard volumetric solution shall be carried out by not less than three 3.1.1 All the reagents used shall be of recognized analytical titrations. grade. 3.2 Apparatus 3.1.2 Distilled or deionized water shall be used in the prepara- tion of reagents and throughout the analysis and redistilled or 3.2.1 Weighing shall be carried out on an analytical balance deionized water shall be used in the determination of trace to the nearest 0,000 2 g. element contents. 3.2.2 The weighing device and laboratory measuring equip- 3.1.3 Before solutions are diluted to the mark in volumetric ment (pipettes, burettes, volumetric flasks, thermometers, flasks, their temperature shall be brought to 20 oC. etc.) shall be verified and appropriate corrections shall be made during the calculation of the analytical results. 3.1.4 The expression "hot water (or solution)" means that the temperature of the liquid is greater than 60 oC, unless other- 3.2.3 Cells for measurement of the absorbance of coloured solutions shall be chosen so that measurements may be carried means that the temperature of the liquid is within the range 40 out in the optimum range of absorbance. to 60 C. 3.1.5 In the expressions "diluted 1 + 1, 1 + 2, 1 + 5, etc." 3.3± Sample2) the first figure indicates the number of parts by volume of con- centrated solution; the second, the number of parts by vol