1、BRITISH STANDARD BS 6092-3: 1981 ISO 1690:1976 Methods of Sampling and test for sodium and potassium silicates for industrial use Part 3: Determination of silica content (gravimetric method) ISO title: Sodium and potassium silicates for industrial use Determination of silica content Gravimetric meth
2、od by insolubilization NOTEIt is recommended that this Part be read in conjunction with the information in the “Generalintroduction” published separately as BS 6092-0. UDC 661.683/.684:546.32284 + 546.33284:543.21.062:546.284 31BS6092-3:1981 This British Standard, having been prepared under the dire
3、ctionof the Chemicals Standards Committee, waspublished under theauthorityofthe ExecutiveBoardand comesintoeffect on 27February1981 BSI 12-1999 The following BSI references related to the work on this standard: Committee references CIC/22 Draft for comment 73/55424 DC ISBN 0 580 12037 6 Amendments i
4、ssued since publication Amd. No. Date of issue CommentsBS6092-3:1981 BSI 12-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 1 7 Expression of results 2 8 Accuracy of the method 2 9 Test report 2 Annex ISO
5、 Publications relating to sodium and potassium silicates for industrial use 3 Publications referred to Inside back coverBS6092-3:1981 ii BSI 12-1999 National foreword This Part of BS6092 is identical with ISO1690 “Sodium and potassium silicates for industrial use Determination of silica content Grav
6、imetric method by insolubilization”, published in1976 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 certain c
7、onventions are not identical with those used in British Standards; attention is especially drawn to the following. The comma has been used throughout 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 “Intern
8、ational Standard” appear, referring to this standard, they should be read as “British Standard”. Cross-references There is no British Standard corresponding directly to ISO1686 to which reference is made in6.1. Technically equivalent information on sampling is given in BS6092-0. The standards listed
9、 in the Annex are intended for information only. Corresponding British Standards are listed in BS6092-0. Additional information Water. Water complying with the requirements of clause 4 is specified in BS3978“Water for laboratory use”. Hydrochloric acid, of approximately1.18g/ml, about36% (m/m) solut
10、ion, which is the corresponding reagent normally obtainable in the United Kingdom, is suitable for use in place of the approximately1.19g/ml solution specified in4.1. WARNING. Aqueous hydrofluoric acid specified in4.3 is a highly corrosive liquid which attacks glass; the vapour is irritant and toxic
11、. Its action on the skin and eyes is strongly corrosive, producing severe and painful burns which may not be immediately evident and which respond slowly to treatment. Samples should be handled only inside a well-ventilated fume cupboard. Rubber gloves, boots and gown of a suitable size to give adeq
12、uate protection to the individual, and full head and face protection must be worn when handling the material. In the event of contact or suspected contact, flood with water and seek immediate medical attention. The manufacturers literature should be consulted for further information. A British Stand
13、ard 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 of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover,
14、an inside front cover, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6092-3:1981 BSI 12-1999 1 1 Scope and fie
15、ld of application This International Standard specifies a gravimetric method by insolubilization for the determination of the silica content of sodium and potassium silicates for industrial use. 2 Reference ISO 1686, Sodium and potassium silicates for industrial use Samples and methods of test Gener
16、al. 3 Principle Insolubilization of silica by evaporation to dryness of a test portion previously acidified with hydrochloric acid. Dissolution of the soluble salts, filtration and washing of the insoluble matter. Second insolubilization by evaporation of the filtrate and washings under the same con
17、ditions. Further dissolution of the soluble salts, filtration and washing of the second insoluble matter. Calcination and weighing of the two lots of insoluble matter simultaneously. Volatilization of silica by heating after addition of hydrofluoric and sulphuric acids and weighing of the residue af
18、ter calcination. The difference in mass represents the silica present in the test portion. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid, approximately1,19g/ml, about38% (m/m) solution or
19、 approximately12N. 4.2 Sulphuric acid, approximately1,84g/ml, about96% (m/m) solution or approximately36N. 4.3 Hydrofluoric acid, approximately1,15g/ml, about40% (m/m) solution. 4.4 Silver nitrate, 10g/l nitric solution. Dissolve1g of silver nitrate in water, add10ml of nitric acid solution, approxi
20、mately1,40g/ml, and make up the volume to100ml. 5 Apparatus Ordinary laboratory apparatus and 5.1 Platinum crucible of height approximately40mm and top diameter30mm, with lid. 5.2 Electric oven, capable of being controlled at100 to 105 C and at110 to120 C. 5.3 Electric furnace, capable of being cont
21、rolled at950to975 C. 6 Procedure 6.1 Test portion and preparation of test solution Weigh, to the nearest0,01g, 10 1g of the test sample (seeISO1686) and place it in a250ml one-mark volumetric flask. Dissolve with water, dilute to the mark and mix. 6.2 Determination Take 25,0ml (corresponding to appr
22、oximately1g of test sample) of the test solution (6.1) and place in a porcelain dish of suitable capacity. Carefully add, while stirring,5ml of the hydrochloric acid solution(4.1). Cover the dish with a watch-glass supported by a glass triangle and place it on a boiling water bath and evaporate to d
23、ryness. Heat the residue in the oven (5.2) controlled at110to 120 C for at least1h. After cooling, add5ml of the hydrochloric acid solution (4.1) and10ml of water. Place on the boiling water bath for5 to10min and stir to dissolve the soluble salts. Filter through an ashless filter paper of medium po
24、rosity, and collect the filtrate quantitatively. Transfer the insoluble product quantitatively onto the filter by means of hot water. Wash with hot water, adding the rinsing water to the filtrate. Continue washing until10ml of the filtrate from the funnel remain clear5min after the addition of10ml o
25、f the nitric solution of silver nitrate (4.4). (Discard this portion of the filtrate.) Transfer the filtrate and the rinsing water quantitatively into the dish already used and evaporate to dryness on a boiling water bath. Heat the residue in the oven (4.2) at110to120 C for at least1h. After cooling
26、, add5ml of the hydrochloric acid solution (4.1) and10ml of water.BS6092-3:1981 2 BSI 12-1999 Place on the boiling water bath for5 to10min and stir in order to dissolve the soluble salts. Filter and wash the insoluble matter on another filter paper by following the procedure given above for the firs
27、t filtration. Fold the filter papers containing the insoluble matter and place them in the platinum crucible(5.1). Dry in the oven controlled at100 to105 C, then ignite the paper with a low flame until the combustion stops. Allow to cool, and wet the residue with a few drops of the sulphuric acid so
28、lution (4.2). Place the crucible and its contents on a hot-plate and evaporate the sulphuric acid. When the emission of white fumes has ceased, place the crucible in the furnace (5.3), controlled at950to975 C, for15min in order to calcine its contents. Allow to cool in a desiccator to ambient temper
29、ature and weigh to the nearest0,0002g. Wet the residue with a few drops of the sulphuric acid solution (4.2) and add, with care, 2to3ml of the hydrofluoric acid solution (4.3). Heat gently on a hot-plate in order to volatilize the hydrofluoric acid and heat more strongly in order to evaporate the su
30、lphuric acid. If any residue remains in the crucible, repeat the treatment with the sulphuric and hydrofluoric acids. Finally, calcine in the furnace controlled at950to975 C for15min, allow to cool in a desiccator to ambient temperature and weigh to the nearest0,0002g. 7 Expression of results The si
31、lica content, expressed as a percentage by mass of SiO 2 , is given by the formula where m 0 is the mass, in grams, of test portion contained in the volume of the solution used; m 1 is the mass, in grams, of the crucible containing the insoluble product before the treatment with hydrofluoric acid; m
32、 2 is the mass, in grams, of the crucible after the treatment with hydrofluoric acid. 8 Accuracy of the method The results obtained using this method are reproducible to the nearest 0,2% (m/m), in absolute value. 9 Test report The test report shall include the following particulars: a) the reference
33、 of the method used; b) the results and the method of expression used; c) any unusual features noted during the determination; d) any operations not included in this International Standard or the International Standard to which reference is made, or regarded as optional. m 1 m 2 () 100 m 0 - BS6092-
34、3:1981 BSI 12-1999 3 Annex ISO Publications relating to sodium and potassium silicates for industrial use ISO 1686, Samples and methods of test General. ISO 1687, Determination of density at20 C of samples in solution Method using density hydrometer and method using pyknometer. ISO 1688, Determinati
35、on of dry matter Gravimetric method. ISO 1689, Calculation of the ratioor. ISO 1690, Determination of silica content Gravimetric method by insolubilization. ISO 1691, Determination of carbonate content Gas-volumetric method. ISO 1692, Determination of total alkalinity Titrimetric method. ISO 2122, P
36、reparation of solution of products not easily soluble in boiling water and determination of matter insoluble in water. ISO 2123, Determination of dynamic viscosity. ISO 2124, Determination of silica content Titrimetric method. ISO 3200, Determination of sulphate content Barium sulphate gravimetric m
37、ethod. ISO 3201, Determination of iron content 1,10-Phenanthroline photometric method. SiO 2 Na 2 O - SiO 2 K 2 O -4 blankBS6092-3:1981 BSI 12-1999 Publications referred to See national foreword.BS 6092-3: 1981 ISO 1690:1976 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI
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