1、BRITISH STANDARD BS 6870-2.2: 1987 ISO 8557:1985 Analysis of aluminium ores Part 2: Chemical methods Section 2.2 Method for determination of hygroscopic moisture in analytical samples: gravimetric method ISO title: Aluminium ores Determination of hygroscopic moisture in analytical samples Gravimetri
2、c method UDC 553.492:543BS6870-2.2:1987 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 28 August1987 BSI 11-1999 The following BSI references relate to the work o
3、n this standard: Committee reference NFM/31 Draft for comment84/41557 DC ISBN 0 580 16054 8 National foreword This Section ofBS6870 has been prepared under the direction of the Non-ferrous Metals Standards Committee. It is identical with ISO8557:1985 “Aluminium ores Determination of hygroscopic mois
4、ture in analytical samples Gravimetric method”, published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certa
5、in conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International
6、 Standard” appear, referring to this standard, they should be read as “Section ofBS6870”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not o
7、f itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will b
8、e indicated in the amendment table on the inside front cover. Cross-reference International Standard Corresponding British Standard ISO 8558:1985 BS 6870 Analysis of aluminium ores Section2.1:1987 Method of preparation of pre-dried test samples (Identical) Amendments issued since publication Amd. No
9、. Date of issue CommentsBS6870-2.2:1987 BSI 11-1999 i Contents Page National foreword Inside front cover 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Material 1 5 Apparatus 1 6 Sampling and samples 1 7 Procedure 1 8 Expression of results 2 9 Test report 2 Publication referred to
10、Inside back coverii blankBS6870-2.2:1987 BSI 11-1999 1 1 Scope and field of application This International Standard specifies a gravimetric loss of mass method for the determination of hygroscopic moisture in analytical samples of aluminium ores. The method is applicable to products having hygroscop
11、ic moisture contents, expressed as water(H 2 O), in the range0,1 to5%(m/m), and shall be used to correct the results obtained for aluminium and loss of mass at1075 C to a dry basis. NOTEThe hygroscopic moisture can be taken into account for other determinations by using a pre-dried sample prepared i
12、n accordance withISO8558. 2 Reference ISO 8558, Aluminium ores Preparation of pre-dried test samples. 3 Principle Drying of the test portion in air at approximately105 C and recording of the loss of mass. 4 Material 4.1 Desiccant: activated alumina, magnesium perchlorate or diphosphorus pentoxide. N
13、OTEActivated alumina should be freshly activated by heating overnight at300 10 C. 5 Apparatus Ordinary laboratory apparatus and 5.1 Weighing bottles, of glass or metal, of diameter approximately50mm. 5.2 Dishes, flat bottom, for equilibration of samples with the laboratory atmosphere. The bottom of
14、the dishes shall be about20cm 2in area. 5.3 Laboratory oven, capable of being controlled at105 2 C. 5.4 Desiccator 6 Sampling and samples 6.1 Sample Use an air-dried sample with a particle size of less than1504m. 6.2 Preparation of the test sample Take approximately10g of the laboratory sample and t
15、ransfer to a dish(5.2). Spread the sample evenly and allow to equilibrate with the laboratory atmosphere for a minimum of2h. 7 Procedure 7.1 Number of determinations Carry out the determination in duplicate on each aluminium ore. 7.2 Preparation of the weighing bottle Dry a weighing bottle and lid(5
16、.1) by heating for1h in the laboratory oven(5.3), controlled at105 2 C. Transfer bottle and lid to the desiccator(5.4), containing a suitable fresh desiccant(4.1), and allow to cool. Weigh to the nearest0,0001g after slightly lifting the lid and quickly replacing it. Record the mass(m 1 ). NOTEA hea
17、t sink introduced into the desiccator and comprising a substantial mass of metal may be used to significantly reduce the cooling time. 7.3 Test portions Weigh, to the nearest0,0001g, approximately2g of pre-equilibrated test sample(6.2) directly into the dried and tared weighing bottle(7.2). Record t
18、he mass(m 2 ). Also at this stage weigh test portions required for the determination of constituents for which correction of the analytical values to a dry basis is required (e.g.loss of mass at1075 C and aluminium content) and transfer such test portions to the vessels specified. 7.4 Determination
19、Transfer the uncovered bottle with its lid to the laboratory oven and dry at105 2 C for1h. Close the bottle, allow to cool in the desiccator for30 to45 min and re-weigh after slightly lifting the lid and quickly replacing it. NOTEWhere a heat sink has been used in the desiccator, a10min cooling time
20、 will be sufficient. Repeat the drying at105 C for30min, cooling in a desiccator for30 to45min, and weighing steps for as many times as necessary to achieve constant mass in the test portion, i.e.until the difference between two successive weighings does not exceed0,02%. Record the constant mass(m 3
21、 ).BS6870-2.2:1987 2 BSI 11-1999 8 Expression of results The hygroscopic moisture content H, expressed as a percentage by mass as water(H 2 O), is given by the formula where m 1 is the mass, in grams, of the weighing bottle; m 2 is the mass, in grams, of the weighing bottle with ore before drying; m
22、 3 is the mass, in grams, of the weighing bottle with ore after drying. Take as the final result the mean of the duplicate determinations. 9 Test report The test report shall include the following information: a) details necessary for the identification of the sample; b) reference to this Internatio
23、nal Standard; c) results of the analysis; d) reference number of the results; e) any characteristics noticed during the determination and any operations not specified in this International Standard or in the International Standard to which reference is made which may have had an influence on the res
24、ults. m 2 m 3 m 2 m 1 -100 BS6870-2.2:1987 BSI 11-1999 Publication referred to Seenational foreword.BS 6870-2.2: 1987 ISO8557:1985 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the
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