1、BRITISH STANDARD BS 6200-3.32.4: 1985 ISO 7692:1983 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.32 Determination of titanium Subsection 3.32.4 Ferrotitanium: volumetric method ISO title: Ferrotitanium Determination of titanium content Titrimetr
2、ic method UDC 669.1:543.24:546.82BS6200-3.32.4:1985 This British Standard, having been prepared under the directionof the Iron and Steel Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31 December 1985 BSI 11-1999 The following BSI references relate
3、to the work on this standard: Committee reference ISM/18 Draft for comment 82/74417 DC ISBN 0 580 14793 2 National foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Committee. It is identical with ISO7692:1983 “Ferrotitanium Determination of tit
4、anium content Titrimetric 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 certain conventions
5、 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 Standard” app
6、ear referring to this standard, they should be read as “British Standard”. Cross-reference. At present there is no corresponding British Standard for ISO3713 which is still at draft stage. Appropriate procedures from ISO3713 will be incorporated in BS6200-2 “Methods of sampling and sample preparatio
7、n”, which will be published in due course. 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 of itself confer immunity from legal obligations
8、. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, 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 insi
9、de front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS6200-3.32.4:1985 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 Reagents 1 5 Apparatus 2 6 Sample 2 7 Procedure 2 8 Expression of re
10、sults 4 9 Test report 5 Figure 1 Bunsen valve 2 Figure 2 Apparatus for titration in an atmosphere of nitrogen 3 Publication referred to Inside back coverii blankBS6200-3.32.4:1985 BSI 11-1999 1 1 Scope and field of application This International Standard specifies a titrimetric method for the determ
11、ination of the titanium content of ferrotitanium. The method is applicable to ferrotitanium having titanium contents between20 and80% (m/m). 2 Reference ISO 3713, Ferroalloys Sampling and preparation of samples General rules 1) . 3 Principle Dissolution of a test portion using sulphuric, hydrofluori
12、c, nitric and hydrochloric acids. Separation of the interfering elements (chromium, vanadium, molybdenum and tin), if present, by precipitation of titanium hydroxide in the presence of hydrogen peroxide. Reduction of the titanium to Ti 3+by aluminium metal in an atmosphere of carbon dioxide or nitro
13、gen. Titration of the Ti 3+with standard volumetric iron(III) ammonium sulphate solution in the presence of thiocyanate as indicator. 4 Reagents During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4
14、.1 Aluminium, of minimum purity99,5%, in the form of foil0,05mm thick, and free from titanium. 4.2 Sodium hydrogen carbonate (NaHCO 3 ). 4.3 Nitric acid, A 1,42g/ml. 4.4 Sulphuric acid, A 1,84g/ml. 4.5 Hydrochloric acid, A 1,19g/ml. 4.6 Hydrofluoric acid, A 1,14g/ml. 4.7 Sulphuric acid, diluted (1+1
15、). Add carefully 1 volume of the sulphuric acid (4.4) to1 volume of water. Cool while mixing. 4.8 Sulphuric acid, diluted (1+4). Add carefully 1 volume of the sulphuric acid (4.4) to4 volumes of water. Cool while mixing. 4.9 Sodium hydroxide,100g/l solution. 4.10 Sodium hydroxide,20g/l solution. 4.1
16、1 Ammonium thiocyanate,100g/l solution. 4.12 Nitrogen, practically oxygen-free (less than10ppm by volume),99,998% pure, or carbon dioxide of similar purity. 4.13 Hydrogen peroxide, 30% or100 volume solution. 4.14 Iron(III) ammonium sulphate Fe 2 (SO 4 ) 3 .(NH 4 ) 2 SO 4 .24H 2 O, standard volumetri
17、c solution. Place 10,2 g of the iron(III) ammonium sulphate in a400ml beaker and add100ml of cold water and50ml of the sulphuric acid (4.7) Transfer quantitatively to a1000ml one-mark volumetric flask and dilute to the mark. 1 ml of this solution corresponds to about1mg of titanium. 4.15 Iron(III) s
18、ulphate solution Dissolve 2 g of pure iron (for example BCS149/3) in50ml of the hydrochloric acid (4.5), oxidize with10ml of the nitric acid (4.3), add40ml of the sulphuric acid solution (4.7) and heat until white fumes are evolved. Cool, dilute to200ml and boil for15min. Cool, transfer quantitative
19、ly to a500ml one-mark volumetric flask and dilute to the mark. 4.16 Titanium sponge or other metallic titanium of purity greater than99,9%. 4.17 Titanium, standard solution corresponding to0,5000g of Ti per litre, prepared by one of the following methods. 4.17.1 Preparation from titanium dioxide Wei
20、gh 0,8340 0,0002g of titanium dioxide which has been previously calcined for2h at800 C. Fuse it gently with10g of potassium pyrosulphate either in a platinum crucible with a cover of the same material, or in a quartz crucible, of capacity170ml, with a cover in the form of a plate, or in a quartz con
21、ical flask. After cooling, dissolve the fusion product directly in the quartz crucible or in the quartz conical flask with100ml of warm water, then decant the solution into a400ml beaker. Rinse the quartz crucible or the quartz conical flask several times. If a platinum crucible is used, place it, a
22、fter cooling, in a400ml beaker with100ml of warm water to dissolve the fusion product. When the product is dissolved, withdraw the crucible, rinsing it several times in the water. Add 50 ml of the sulphuric acid solution (4.8) to the solution of the fusion product. Heat gently on a hot-plate until t
23、he solution becomes completely clear. Cool, transfer quantitatively to a1000ml one-mark volumetric flask, dilute to the mark with water and mix. 1) At present at the stage of draft.BS6200-3.32.4:1985 2 BSI 11-1999 4.17.2 Preparation from potassium hexafluorotitanate Weigh 2,5060 0,0002g of potassium
24、 hexafluorotitanate (K 2 TiF 6 ) which has been previously dried for2h at105 C into a platinum crucible. Place the crucible in a100ml beaker, add50ml of the sulphuric acid solution (4.8) and heat until the potassium hexafluorotitanate is dissolved (about15min). Cool, withdraw the crucible, rinsing i
25、t several times with the water. Transfer quantitatively to a1000ml one-mark volumetric flask and, after cooling, dilute to the mark with water and mix. 5 Apparatus Usual laboratory equipment and in particular 5.1 PTFE beakers, of capacity250ml. 5.2 Glass beakers, of capacity600ml. 5.3 Flask, conical
26、 or round with a flat-base, of capacity500ml. 5.4 Bunsen valve or Goeckel condenser/bulb. The Bunsen valve (seeFigure 1) comprises a rubber bung (1) through which two glass tubes (2 and6) pass. Rubber tubes (3) are fitted onto these glass tubes, the upper ends being closed by glass plugs (5). The ru
27、bber tube (3), which is fitted on the glass tube(2), is slitted (4) for a length of10 to15mm in the middle of its length by a razor blade. The tube(6) which ends5cm above the level of the solution to be titrated makes it possible to introduce nitrogen or carbon dioxide by substituting the tube throu
28、gh which the gas is delivered for the rubber tube (3). 5.5 Magnetic stirrer, with a PTFE covered stirring bar. 5.6 Apparatus for titration in an atmosphere of nitrogen (seeFigure 2). 6 Sample Use powder which will pass through a sieve of aperture size1604m, prepared in accordance with ISO3713. 7 Pro
29、cedure 7.1 Test portion Take a test portion of1 0,0002g. 7.2 Blank test Carry out a blank test in parallel with the determination, following the same procedure and using the same quantities of all the reagents except the iron(III) ammonium sulphate solution (4.14), but omitting the test portion. 7.3
30、 Control test Check the validity of the operating procedures used by carrying out, in parallel with the determination and following the same procedure, the determination(s) of the titanium content(s) of one or several samples of the same type, having known titanium content(s). Figure 1 Bunsen valveB
31、S6200-3.32.4:1985 BSI 11-1999 3 7.4 Standardization of the iron(III) ammonium sulphate solution 7.4.1 Method using titanium sponge Carry out the determination on a test portion of the titanium sponge (4.16) weighing0,75 to0,85g. 7.4.2 Method using standard titanium solution By means of a pipette, tr
32、ansfer to a500ml conical flask,50ml of the standard titanium solution(4.17),5ml of the sulphuric acid solution(4.7) and80ml of the hydrochloric acid(4.5). Proceed as specified in7.5.3.2. Carry out a blank test under the same conditions in order to verify the absence of titanium in the reagents used
33、for preparation of the standard solution. 7.5 Determination 7.5.1 Dissolution of the test portion Place the test portion in a250ml PTFE beaker, and add about20ml of water and35ml of the sulphuric acid solution (4.7). When the reaction has slowed, add20ml of the hydrochloric acid (4.5) and1ml of the
34、hydrofluoric acid (4.6). Cover the beaker with a PTFE cover. Oxidize while cold by adding, drop by drop,5ml of the nitric acid (4.3). When the reaction is complete, remove the cover and heat gently until white fumes are evolved. Continue heating for about5min. Cool, add30ml of the hydrochloric acid
35、(4.5), stir gently, cover and heat on a hot-plate until the solution becomes clear. Rinse the cover with5ml of the hydrochloric acid(4.5). Cool and transfer the solution to a500ml one-mark volumetric flask, rinse the beaker and dilute to the mark with water (solutionA). Figure 2 Apparatus for titrat
36、ion in an atmosphere of nitrogenBS6200-3.32.4:1985 4 BSI 11-1999 If the expected titanium content of the sample lies in the range20 to45% (m/m), take exactly50ml of solution A; if the expected titanium content lies in the range45 to75% (m/m), take exactly25ml of solutionA. Transfer this aliquot port
37、ion to a250ml squat beaker containing10ml of the iron(III) sulphate solution (4.15) if interfering elements are to be separated, proceeding as specified in7.5.2, or into a500ml conical flask if this separation is not to be carried out, proceeding as specified in7.5.3.1. 7.5.2 Separation of interferi
38、ng elements Add to the aliquot portion of solution A in the250ml beaker50ml of the sodium hydroxide solution (4.9) and2ml of the hydrogen peroxide solution (4.13), heat to boiling and keep boiling for5min. Allow the precipitate to settle and filter either through a fast double filter or through a fi
39、lter lined with paper pulp. After having transferred all the hydroxide precipitate onto the filter, wash the filter assembly and the precipitate with the sodium hydroxide solution (4.10) and rinse the beaker and the precipitate six times with about10ml of the sodium hydroxide solution (4.10). Rinse
40、the stem of the funnel with water and place the funnel on a500ml conical flask. Place in the 250 ml beaker45ml of the hydrochloric acid (4.5) and15ml of the sulphuric acid solution(4.8) and heat to60 to70 C. Using this acid mixture, dissolve the hydroxide precipitate on the filter, adding the mixtur
41、e in fractions of10ml and allowing each fraction to run away completely before repeating the addition. When the beaker is empty, add35ml of the hydrochloric acid (4.5), heat as before, and wash the filter with fractions of about10ml of the hydrochloric acid. Finally rinse the beaker, the filter and
42、the stem of the funnel with hot water (70 to80 C), using a total volume not exceeding40ml. Proceed as specified in7.5.3.2. 7.5.3 Titration 7.5.3.1 Absence of interfering elements Add to the aliquot portion of solution A in the500ml conical flask85ml of the hydrochloric acid (4.5) and25ml of water. P
43、roceed as specified in7.5.3.2. 7.5.3.2 Reduction of titanium Add to the test solution (prepared in7.5.2 or7.5.3.1)2 0,2g of the sodium hydrogen carbonate (4.2) and4 0,2g of the aluminium (4.1), cut into several pieces. Immediately stopper the flask with the Bunsen valve or Goeckel condenser/bulb (se
44、e5.4) filled with saturated sodium hydrogen carbonate solution 2) . Agitate very frequently during the reduction. 7.5.3.3 Titration in an atmosphere of nitrogen Before the aluminium is totally dissolved, connect the descending tube (6) of the Bunsen valve to the nitrogen source after having withdraw
45、n the rubber tube (3). Adjust the nitrogen flow to0,7 0,1l/min. When the aluminium is dissolved (cessation of effervescence), immerse the flask totally in cold water and allow the nitrogen to escape through the slit (4) in the rubber tube (3) and leave until the solution is at ambient temperature (a
46、bout7min is required). Without interrupting the flow of nitrogen, lift the Bunsen valve and add10ml of the ammonium thiocyanate solution (4.11) and the bar of the magnetic stirrer (see5.5); rinse the descending tube(6) with cold boiled water and replace the Bunsen valve with the titration assembly (
47、seeFigure 2), after having connected it to the source of nitrogen. Place on the magnetic stirrer (5.5) and titrate with the iron(III) ammonium sulphate solution (4.14) until a persistent pink colour is obtained. 7.5.3.4 Titration in an atmosphere of carbon dioxide When the aluminium is dissolved, co
48、ol the solution and withdraw the Bunsen valve or the Goeckel condenser bulb. Add10ml of the ammonium thiocyanate solution (4.11) and titrate with the iron(III) ammonium sulphate solution (4.14) until a persistant pink colour is obtained. 8 Expression of results 8.1 If the iron(III) ammonium sulphate
49、 solution was standardized by the method using titanium sponge (see7.4.1), the titanium content, expressed as a percentage by mass, is given by the formula 2) At the end of the reduction, suction may be produced in the Goeckel valve and it will then be necessary to add the saturated sodium hydrogen carbonate solution rapidly. m 1 V 2 V 1 - V 3 V 1 m 2 - 100 BS6200-3.32.4:1985 BSI 11-1999 5 where V 1 is the volume, in millilitres, of iron(III) ammonium sulphate solution (4.14) used in the blank tes
