ISO-7335-1987.pdf
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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOAHAR OPrAHWSAL(blfl n0 CTAHAAPTkl3AL(klkl Iron ores - Determination of combined water content - Karl Fischer titrimetric method Minerais de fer - Dosage de leau de constitution
2、 - Mkthode titrimktrique de Karl Fischer IS0 7335 First edition 1987-12-15 Reference number IS0 7335 : 1987 (E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:29:46 MDTNo rep
3、roduction or networking permitted without license from IHS -,-,- Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical c
4、ommittees. 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
5、 adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 73
6、35 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. 0 International Organization
7、 for Standardization, 1987 0 Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:29:46 MDTNo reproduction or networking permitted without license from IHS -
8、,-,- INTERNATIONAL STANDARD IS0 7335: 1987 (E) Iron ores - Determination of combined water content - Karl Fischer titrimetric method 1 Scope and field of application This International Standard specifies a titrimetric method for the determination of the combined water content of iron ores, using Kar
9、l Fischer solution. This method is applicable to a concentration range of 0,05 to 10 % (m/m) of combined water in natural iron ores, and iron ore concentrates and agglomerates including sinter products. NOTE - The term “combined water” means that part of the water content of an iron ore that can be
10、removed only at temperatures substantially higher than 100 to 110 OC. 2 References IS0 385, Laboratory glassware - Burettes. IS0 3081, Iron ores - Increment sampling - Manualmethod. IS0 3082, Iron ores - Increment sampling and sample prepara- tion - Mechanical method. IS0 3083, Iron ores - Preparati
11、on of samples - Manual method. IS0 7764, Iron ores - Preparation of predried test samples for chemical analysis. 3 Principle Liberation of adventitious hygroscopic moisture by heating the predried test portion at 105 “C in a furnace in a stream of dry nitrogen. Successive heating up to 950 =C in ano
12、ther furnace and collection of the liberated combined water in ethylene glycol-methanol mixture. Measurement of combined water content by titration with Karl Fischer solution using electrometric detection of the end point. 4 Reagents During the analysis, use only reagents of recognized analytical gr
13、ade and only distilled water or water of equivalent purity. 4.1 Desiccant. Silica gel, self-indicating granules. 4.2 Desiccant. Anhydrous magnesium perchlorate Mg(ClO this solution shall previously be standardized by use of the following b), c) or d); b) water added by means of a microsyringe; c) ci
14、tric acid monohydrate COH)(COOH)(CH2COOH)zH201; d) disodium tartrate dihydrate (CHOH . COONa),2HzOl. 5 Apparatus A suitable apparatus for the determination is illustrated in figure 1 (two-furnaces-in-series type) or in figure 2 (interchangeable furnace type). 5.1 Gas flowmeter, capable of measuring
15、a flow rate up to 250 ml/min. If a pressure drop over a constriction is used as a means of measuring flow rate, the manometer liquid shall be a non-volatile oil. 5.2 Drying towers (tt and t.J, of 250 ml capacity, packed respectively with desiccant (4.1) and (4.2) to dry the stream of nitrogen enteri
16、ng the heating tube. 5.3 Heating furnaces (ft and fz). Electric furnaces in series as in figure 1 or movable furnaces which can be located around, and removed from, the heating tube as in figure 2. The furnaces shall be capable of maintaining temperatures of 105 +2 X and 950 I!I 20 OC, respectively,
17、 over a minimum tube length of about 150 mm, by controlling the electric cur- rent. Furnace temperatures shall be measured at the upper sur- face of the heating tube by means of a pyrometer or ther- mometer. 1 Copyright International Organization for Standardization Provided by IHS under license wit
18、h ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:29:46 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 7335 : 1987 (E) 5.4 Heating tube. A silica tube as shown in figure 1, of about 30 mm inside diameter, about 800 mm length, and pro- v
19、ided with a long silica pushing rod. Another example (figure 2) is about 350 mm long, closed at one end and fitted with a thin inner tube of about 8 mm external diameter, through which gas flows towards the outlet. 6.2 Preparation of predried test samples Thoroughly mix the laboratory sample and, ta
20、king multiple in- crements, extract a test sample in such a manner that it is representative of the whole contents of the container. Dry the test sample at 105 + 2 OC as specified in IS0 7764. (This is the predried test sample.) 5.5 Sample boats, of an inert and stable material such as quartz, plati
21、num or porcelain. Approximate dimensions are 100 mm length, 20 mm width and 5 mm height, and sample loading shall not exceed 1 mg/mm* for 0,2 to 1 g test portions and I,5 mg/mm2 for 3 g test portions. Before use, boats shall be heated at 950 OC, cooled and stored in a desiccator to maintain freedom
22、from moisture. 7 Procedure 7.1 Number of determinations Carry out the analysis at least in duplicate in accordance with annex A, independently, on one predried test sample. 5.6 Filter. Sintered metal, sintered glass or similar filter disc inserted in the flexible connection between the heating tube
23、and the inlet to the absorption cell. 5.7 Flexible connections. Neoprene elastometer tubing is suitable. Some types of silicone tubing have been found to be permeable. For the gas flow lines after the drying towers, glass tubing should be used to the maximum extent possible, with the flexible tubing
24、 being used only for the connection of butt- jointed glass sections. NOTE - The expression “independently” means that the second and any subsequent result is not affected by the previous result(s). For this particular analytical method this condition implies that the repetition of the procedure shal
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