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1、BRITISH STANDARD Addendum No. 1 (1976) to BS 1902-2.3: 1970 Incorporating Amendment No. 1 Methods of testing Refractory materials Section 2.3: Chemical analysis of magnesites and dolomites Addendum No. 1: Determination of boron in magnesites UDC 666.76 + 666.762.32:543.062.546.27 Licensed Copy: shef
2、fieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Addendum No. 1 (1976) to BS 1902-2.3:1970 This British Standard, having been prepared under the direction of the Refractory Products Standards Committee, was published under the authority of the Executive Board o
3、n 28 May 1976 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference RPM/1 Draft for comment 75/42144 DC ISBN 0 580 09264 X A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible
4、 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, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been upd
5、ated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments 5213March 1987Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, n
6、a, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Addendum No. 1 (1976) to BS 1902-2.3:1970 BSI 11-1999i Contents Page 1Scope1 2References1 3Principle of the method and its range1 4Reagents1 5Procedure1 6Correction for titanium content2 7Calibration2 8Calculation of results3 Publicat
7、ions referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Addendum No. 1 (1976) to BS 1902-2.3:1970 B
8、SI 11-19991 1 Scope This addendum, which is to be read in conjunction with BS 1902-2.3, describes the method for the determination of boron in magnesites. It is not applicable to dolomite materials. 2 References The titles of the publications referred to in this addendum are listed on inside back co
9、ver. 3 Principle of the method and its range 3.1 Principle. The sample is extracted with dilute sulphuric acid and, after dilution to a standard volume, boron is determined in an aliquot by a carminic acid spectrophotometric method. The latter part of the method is carried out in concentrated sulphu
10、ric acid and the appropriate care should be exercised in handling the solution. The wavelengths for the spectrophotometric measurements have been chosen so as to eliminate interference from vanadium and to allow a simple correction to be made for the titanium content of the sample (see 3.4). 3.2 Ran
11、ge. The method allows determinations to be made within two ranges of boron content. Using a 2 g sample and diluting to 50 ml the range is 0 to 0.075 % B2O3; using a 1 g sample and diluting to 100 ml the range is 0 to 0.30 % B2O3. It is not permissible to extrapolate the calibration graph above the t
12、op point specified in the procedure as the calibration is not linear at higher optical densities. 3.3 Precision 3.4 Interference from titania content. The presence of 1 % TiO2 in the sample gives an apparent boron content of approximately 0.04 %. In general, the titania content of magnesite does not
13、 exceed 0.1 % unless it has been specifically added or is a contaminant. Its effect can be allowed for without determining the titania content of the sample (see clause 6). 4 Reagents 4.1 General. Unless otherwise stated, all reagents shall be of analytical grade, where available, and distilled wate
14、r shall be used throughout the analysis. 4.2 Solid reagents 4.2.1 Boric acid 4.2.2 Carminic acid, Purified. 4.3 Solutions 4.3.1 Carminic acid (0.5 g/l). Dissolve 0.1 g of carminic acid in 200 ml of concentrated sulphuric acid (d = 1.84) with stirring. 4.3.2 Sulphuric acid (d = 1.84, 36N approximatel
15、y). 4.3.3 Sulphuric acid (1 + 3). Cautiously add 100 ml of sulphuric acid (d = 1.84) to 300 ml of water, cooling the solution and keeping it well mixed during the addition of the acid. 4.3.4 Titanium solution (1 mg TiO2/ml approximately). To 150 ml of BDH titanium sulphate standard solution (1 mg Ti
16、/ml for atomic absorption spectrophotometry) add 10 ml of dilute sulphuric acid (1 + 3) and dilute to 250 ml with water. 4.4 Standard solutions 4.4.1 Boron solution A (300 p.p.m. B2O3). Dissolve 0.5328 g of boric acid in water and dilute to 1 litre in a volumetric flask. Store in a polyethylene bott
17、le. 4.4.2 Boron solution B (30 p.p.m. B2O3). Dilute 25 ml of the boron solution A to 250 ml in a volumetric flask. Store in a polyethylene bottle. 5 Procedure 5.1 Preparation of sample. Grind the sample for analysis so that it passes through a 125 4m nominal aperture sieve complying with the require
18、ments of BS 410. A non-metallic sieve (e.g. a nylon bolting cloth sieve) is preferable. 5.2 Decomposition of the sample. Weigh 1.000 g of the prepared sample, previously ground and dried at 110 C, on to a small watch glass and transfer to a 100 ml beaker. For samples containing less than 0.07 % B2O3
19、 use a 2 g sample instead of a 1 g sample. Standard deviation = 0.0005 % using the procedure involving a 2 g sample; Standard deviation = 0.002 % using the procedure involving a 1 g sample. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Add
20、endum No. 1 (1976) to BS 1902-2.3:1970 2 BSI 11-1999 Add 20 ml of dilute sulphuric acid (1 + 3), cover the beaker with a clock glass and heat to incipient boiling for 15 min to 30 min. An insoluble residue, consisting mainly of silica, may remain. Cool the solution to room temperature, transfer to a
21、 100 ml volumetric flask1), without filtering, and dilute to the mark with water. If a 2 g sample has been used, transfer the solution to a 50 ml volumetric flask instead of to a 100 ml flask. 5.3 Determination of boron. Filter a portion of the solution through a dry ashless grade medium filter pape
22、r2) into a dry beaker, discarding the first few millilitres. Do not wash. Transfer a 4 ml aliquot of the filtered solution to a dry 50 ml volumetric flask (preferably polypropylene). In a second dry flask prepare a blank solution by adding 4 ml of water by pipette. To each flask carefully add 20 ml
23、of sulphuric acid (d = 1.84) and cool in running water. Then stand the flasks, together with the concentrated sulphuric acid and carminic acid solution, in a thermostatically controlled water bath at 25 C. After about 10 min add to each flask by pipette3)20 ml of the carminic acid solution, allowing
24、 an appropriate drainage time. Dilute each solution to 50 ml with sulphuric acid (d = 1.84), mix and allow to stand for 3 h in the thermostatically controlled water bath at 25 C. Measure the optical density of the sample solution against that of the blank solution in 10 mm cells at 610 nm and at 730
25、 nm. 6 Correction for titanium content Transfer by pipette 10 ml of the titania solution (1 mg TiO2/ml approximately) to a 50 ml volumetric flask, add 20 ml of dilute sulphuric acid (1 + 3) and dilute to 50 ml with water. Transfer a 4 ml aliquot of this solution (= 0.5 % TiO2 in the procedure involv
26、ing a 2 g sample) to a dry 50 ml volumetric flask (preferably polypropylene). Into a similar flask pipette 4 ml of water. To each flask carefully add 20 ml of sulphuric acid (d = 1.84) and cool in running water. Then stand the flasks, together with the concentrated sulphuric acid and carminic acid s
27、olution, in a thermostatically controlled water bath at 25 C. After about 10 min add to each flask by pipette3)20 ml of the carminic acid solution, allowing the appropriate drainage time. Dilute each solution to 50 ml with sulphuric acid (d = 1.84), mix and allow to stand for 3 h in the thermostatic
28、ally controlled water bath at 25 C. Measure the optical density of the titanium-containing solution against that of the blank solution in 10 mm cells at 610 nm and at 730 nm. Calculate the ratio (R) of the optical densities due to the titanium complex at these two wavelengths from the expression NOT
29、EThe value of R is usually about 1.75. To avoid calibration errors, the spectrophotometer used for measuring the optical densities of the titanium-containing solution shall be the same individual instrument as that used for measuring the optical densities of the sample solution (see 5.3). 7 Calibrat
30、ion Transfer 0, 1 ml, 2 ml, 3 ml and 4 ml of the boron solution B to dry 50 ml volumetric flasks (preferably polypropylene) and dilute each solution to exactly 4 ml with water. To each flask carefully add 20 ml of sulphuric acid (d = 1.84) and cool in running water. Then stand the flasks, together w
31、ith the concentrated sulphuric acid and carminic acid solution, in a thermostatically controlled water bath at 25 C. After about 10 min add to each flask by pipette3)20 ml of the carminic acid solution, allowing an appropriate drainage time. Dilute each solution to 50 ml with sulphuric acid (d = 1.8
32、4), mix and allow to stand for 3 h in the thermostatically controlled water bath at 25 C. Measure the optical density of each solution against that of the zero solution in 10 mm cells at 610 nm. From the optical densities prepare a calibration graph. NOTEThe calibration graph so prepared is suitable
33、 both for a B2O3 content of 0 to 0.30 % when the procedure involving a 1 g sample is used and for a B2O3 content of 0 to 0.075 % when the procedure involving a 2 g sample is used. To avoid calibration errors, the spectrophotometer used to measure the optical densities of the calibration solutions sh
34、all be the same individual instrument as that used for measuring the optical densities of the sample solution (see 5.3) and of the titanium containing solution (see clause 6). A fresh calibration graph shall be prepared for each new supply of solid carminic acid reagent. 1) See BS 1792. 2) A Whatman
35、 No. 40 paper is suitable. 3) CAUTION. Use a pipette filler. R optical density at 610 nm optical density at 730 nm - -= Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Addendum No. 1 (1976) to BS 1902-2.3:1970 BSI 11-19993 8 Calculation of r
36、esults Calculate the true optical density due to boron at 610 nm from the expression: Determine the B2O3 content of the sample by referring the true optical density due to boron at 610 nm to the calibration graph prepared in accordance with clause 7. = D610 (R D730) where is the true optical density
37、 due to boron at 610 nm; D610is the optical density at 610 nm due to the boron and titanium complexes, measured in accordance with 5.3; D730is the optical density at 730 nm due to the titanium complex only, measured in accordance with 5.3; Ris the ratio of the optical densities due to the titanium c
38、omplex at 610 nm and 730 nm, determined in accordance with clause 6. D610 B2O3 D610 B2O3 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:16:16 GMT+00:00 2006, Uncontrolled Cop
39、y, (c) BSI Addendum No. 1 (1976) to BS 1902-2.3:1970 BSI 11-1999 Publications referred to BS 410, Test sieves. BS 1792, One-mark volumetric flasks. BS 1902, Methods of testing refractory materials. BS 1902-2.3, Chemical analysis of magnesites and dolomites. Licensed Copy: sheffieldun sheffieldun, na
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