1、 Reference number ISO 589:2008(E) ISO 2008INTERNATIONAL STANDARD ISO 589 Fourth edition 2008-11-01 Hard coal Determination of total moisture Houille Dtermination de lhumidit totale ISO 589:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy
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6、 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedISO 589:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1
7、 4 Principle. 2 5 Reagent 2 6 Apparatus 3 7 Sample . 3 8 Procedure 4 9 Precision 7 10 Test report . 8 Bibliography . 9 ISO 589:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member b
8、odies). 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, governmental a
9、nd non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives
10、, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies ca
11、sting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 589 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommitte
12、e SC 5, Methods of analysis. This fourth edition cancels and replaces the third edition (ISO 589:2003), which has been technically revised. ISO 589:2008(E) ISO 2008 All rights reserved v Introduction Moisture is an important parameter in respect of coal quality. The moisture content of coal is not a
13、n absolute value and conditions for its determination have to be standardized. It is expected that the results given by the different methods specified here should be comparable within the limits of the tolerance quoted. It is always necessary that the determination of the total moisture content of
14、hard coals be considered in close connection with sampling. Therefore, this International Standard has been prepared in close relationship with the ISO standards for mechanical sampling ISO 13909 (all parts) and manual sampling ISO 18283. A major problem with the preparation of test samples for the
15、determination of moisture is the risk of bias due to inadvertent loss of moisture. This is dependent on the tightness of the sealing of sampling containers, the level of moisture content in the sample, the ambient conditions, the type of coal and the reduction and division procedures used. This is d
16、escribed in detail in ISO 13909-4 or ISO 18283. Depending on the mass, the nominal top size and the facilities available where samples are taken, it is possible to dry the sample directly after sampling (air-drying), then to reduce the particle size and prepare a test sample for determination of moi
17、sture in the air-dried sample. Alternatively, the whole sample may be transported to the laboratory and the total moisture determined. INTERNATIONAL STANDARD ISO 589:2008(E) ISO 2008 All rights reserved 1 Hard coal Determination of total moisture 1 Scope This International Standard describes two met
18、hods for determination of the total moisture content of hard coals, a two-stage method and a single-stage method. For either method there is a choice between drying in air and drying in a nitrogen atmosphere. Depending on the coal rank, there may be systematic differences between the results obtaine
19、d by drying in the different atmospheres on subsamples of the same sample. Drying in a nitrogen atmosphere is suitable for all hard coals, while drying in air is only suitable for hard coals not susceptible to oxidation. NOTE The term “not susceptible to oxidation” cannot be defined easily. Usually,
20、 high-rank coals such as anthracites are not oxidized under the conditions described in this International Standard. For all other types of coal, this has to be verified by experiments. 2 Normative references The following referenced documents are indispensable for the application of this document.
21、For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1213-2, Solid mineral fuels Vocabulary Part 2: Terms relating to sampling, testing and analysis ISO 11722, Solid mineral fuels Hard Coal
22、 Determination of moisture in the general analysis test sample by drying in nitrogen ISO 13909-1, Hard coal and coke Mechanical sampling Part 1: General introduction ISO 13909-2, Hard coal and coke Mechanical sampling Part 2: Coal Sampling from moving streams ISO 13909-3, Hard coal and coke Mechanic
23、al sampling Part 3: Coal Sampling from stationary lots ISO 13909-4:2001, Hard coal and coke Mechanical sampling Part 4: Coal Preparation of test samples ISO 18283:2006, Hard coal and coke Manual sampling 3 Terms and definitions For the purposes of this document, the terms and definitions given in IS
24、O 1213-2 apply. ISO 589:2008(E) 2 ISO 2008 All rights reserved4 Principle 4.1 Method A Two-stage methods 4.1.1 Method A 1 Drying under nitrogen in second stage The sample is dried in air at ambient temperatures or at elevated temperatures not exceeding 40 C (first or free-moisture stage) and the los
25、s in mass recorded. The air-dried sample is crushed to 2,8 mm nominal top size and subsamples are dried at 105 C to 110 C in a nitrogen-flushed oven (second or residual moisture stage). NOTE Residual moisture is often called moisture in the air-dried sample. Provided that the result obtained for the
26、 determination of moisture in the analysis sample in accordance with ISO 11722 can be shown to give the same result as that for the second-stage moisture determination, the former may be used. The moisture is calculated from the loss in mass at each of the two stages. 4.1.2 Method A 2 Drying in air
27、The sample is dried in air at ambient temperatures or at elevated temperatures not exceeding 40 C (first or free-moisture stage) and the loss in mass recorded. The air-dried sample is crushed to 2,8 mm nominal top size and subsamples are dried in air at 105 C to 110 C (second or residual moisture st
28、age). The moisture is calculated from the loss in mass at each of the two stages. NOTE This method is suitable only for hard coals not susceptible to oxidation. 4.2 Method B Single-stage methods 4.2.1 Method B 1 Drying under nitrogen The sample is crushed to a nominal top size of either 11,2 mm or,
29、alternatively, 10 mm. A subsample is dried in a nitrogen-flushed oven at a temperature of 105 C to 110 C. The moisture is calculated from the loss in mass. 4.2.2 Method B 2 Drying in air The sample is crushed to a nominal top size of either 11,2 mm or, alternatively, 10 mm. A subsample is dried in a
30、ir at a temperature of 105 C to 110 C. The moisture is calculated from the loss in mass. NOTE This method is suitable only for hard coals not susceptible to oxidation. 5 Reagent Nitrogen, moisture-free, having an oxygen content of less than 30 l/l. NOTE Commercially available nitrogen with a water c
31、ontent of less than 5 l/l does not require further drying. ISO 589:2008(E) ISO 2008 All rights reserved 3 6 Apparatus 6.1 Method A 6.1.1 Oven, for first-stage moisture determination, capable of being controlled at a temperature of 30 C to 40 C, with a sufficiently rapid rate of atmosphere change (e.
32、g. 5 times per hour). The air velocity shall be such that the sample particles are not dislodged from their tray. 6.1.2 Nitrogen-flushed oven, for second-stage moisture determination, capable of being controlled at a temperature of 105 C to 110 C, with the additional provision for passing a current
33、of dry nitrogen through it at a flow rate about 15 times the oven volume per hour. The gas velocity shall be such that the sample particles are not dislodged from their dish. 6.1.3 Oven, for second-stage moisture determination, capable of being controlled at a temperature of 105 C to 110 C, with a s
34、ufficiently rapid rate of atmosphere change (e.g. 5 times per hour). The air velocity shall be such that the sample particles are not dislodged from their dish. 6.2 Method B 6.2.1 Nitrogen-flushed oven, for method B 1, capable of being controlled at a temperature of 105 C to 110 C, with the addition
35、al provision for passing a current of dry nitrogen through it at a flow rate about 15 times the oven volume per hour. The nitrogen velocity shall be such that the sample particles are not dislodged from their tray. 6.2.2 Oven, for method B 2, capable of being controlled at a temperature of 105 C to
36、110 C and with a sufficiently rapid rate of atmosphere change (e.g. 5 times per hour). The air velocity shall be such that the sample particles are not dislodged from their tray. 6.3 Methods A and B 6.3.1 Weighing tray, made of heat- and corrosion-resistant material of such dimensions that the loadi
37、ng of the coal layer does not exceed 1 g/cm 2 . 6.3.2 Weighing dishes, shallow vessels of glass, silica or corrosion-resistant metal with well-fitting covers of such a size that the loading of the coal layer does not exceed 0,3 g/cm 2 . 6.3.3 Apparatus for size reduction (to 11,2 mm or 10,0 mm and 2
38、,8 mm), without significant loss in moisture content. 6.3.4 Balance, capable of weighing to 0,1 g. 6.3.5 Analytical balance, capable of weighing to the nearest 1 mg. 6.3.6 Sample divider, e.g. riffle divider. 7 Sample 7.1 General Depending on the mass, the nominal top size and the facilities availab
39、le where samples are taken, it is possible to dry the sample (air-drying) directly after sampling, then to reduce the particle size and prepare a test sample for determination of moisture in the air-dried sample (“on-site treatment”). Alternatively, the whole sample may be transported to the laborat
40、ory and the moisture determined. ISO 589:2008(E) 4 ISO 2008 All rights reserved7.2 Sampling and sample preparation Sampling shall be made in accordance with ISO 13909-1, ISO 13909-2 and ISO 13909-3 for mechanical sampling, or ISO 18283 for manual sampling. On-site sample preparation shall be carried
41、 out in accordance with ISO 13909-4 for mechanical sampling, or ISO 18283 for manual sampling. NOTE If convenient, samples for moisture determination may be extracted from a common sample for both moisture and general analysis; see ISO 13909-4 or ISO 18283. 7.3 Precautions against loss of moisture O
42、ne of the main difficulties in determining total moisture is that of minimizing changes in the moisture content of the sample while preparing the final sample. Every precaution shall be taken to minimize change of moisture due to the use of unsuitable containers and by evaporation during handling, p
43、articularly if the coal is extremely wet. All moisture samples shall be kept in sealed containers in a cool place before and after preparation, as well as during any interval between stages of sample preparation. Care needs to be taken to minimize the change of moisture during particle size reductio
44、n, by using equipment in which there is no appreciable heating and by reducing to a minimum the amount of air passing through the mill. Machines that crush are preferable to those that grind, as the latter have a greater tendency to generate heat. Care should also be taken to minimize change of mois
45、ture when carrying out sample division, and all such operations should be carried out as quickly as possible. 7.4 Moisture determination with on-site air-drying Method A only If the sample has already been air-dried directly after sampling (in accordance with ISO 13909-4, alternatively ISO 18283), i
46、t can then be crushed to 2,8 mm nominal top size. The amount of the crushed sample shall not be less than 650 g and step 8.1.1 can be skipped in the laboratory. It is necessary to check that the air-dried sample does not take up or lose moisture when it is transported to the laboratory. 7.5 Moisture
47、 determination without on-site air-drying Methods A and B Samples for the determination of moisture shall be received in air-tight containers. The sample mass shall not be less than the minimum mass stated in ISO 13909-4:2001, Table 1 and in ISO 18283:2006, Table 3 (which are the same). If the coal
48、is so wet that water separates from the coal in the sample container, the whole of the sample and the container shall be air-dried until this condition no longer applies and the loss in mass is recorded. 8 Procedure 8.1 Methods A 1 and A 2 Two-stage methods 8.1.1 First-stage moisture Free moisture W
49、eigh a dry, empty tray (6.3.1), transfer the sample (7.5) to the tray and spread evenly, so that the loading of the coal layer does not exceed 1 g/cm 2 . Weigh the sample to the nearest 0,1 g. If the loading is too high for one tray, use two or more. ISO 589:2008(E) ISO 2008 All rights reserved 5 Weigh the tray(s) plus sample and place it/them in the drying oven at ambient temperature. Remove the trays when a constant mass is reached. To shorten the time required for
