1、BRITISH STANDARD BS 6870-2.7: 1987 ISO 6995:1985 Analysis of aluminium ores Part 2: Chemical methods Section 2.7 Method for determination of titanium content: spectrophotometric method ISO title: Aluminium ores Determination of titanium content 4,4-Diantipyrylmethane spectrophotometric method UDC 55
2、3.492:543BS6870-2.7:1987 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee, waspublished under the authorityof the Board of BSI andcomes into effect on 28August1987 BSI 01-2000 The following BSI references relate to the work on this standard
3、: Committee reference NFM/31 Draft for comment 83/76596 DC ISBN 0 580 16060 2 National foreword This Section of BS 6870 has been prepared under the direction of the Non-ferrous Metals Standards Committee. It is identical with ISO6995:1985 “Aluminium ores Determination of titanium content 4,4-Diantip
4、yrylmethane spectrophotometric 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 conve
5、ntions 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 Standar
6、d” appear, referring to this standard, they should be read as “Section of BS6870”. Additional information. When adopting the text of the International Standard, it was noticed that in4.6 and4.7 hydrochloric acid with a density of1.17g/ml is specified, whereas in the UK hydrochloric acid with a densi
7、ty of1.18g/ml is normally used. This difference, which will not affect the determination, has been brought to the attention of ISO in a proposal to amend the International Standard by specifying a wider range for the density of the hydrochloric acid required. A British Standard does not purport to i
8、nclude 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, an inside front cover, pa
9、gesi andii, pages1 to6, 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. Cross-reference International Standard Corresponding British Standard
10、ISO 5725:1986 BS 5497 Precision of test methods Part 1:1987 Guide for the repeatability and reproducibility for a standard test method by inter-laboratory tests (Identical) Amendments issued since publication Amd. No. Date of issue CommentsBS6870-2.7:1987 BSI 01-2000 i Contents Page National forewor
11、d Inside front cover 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Sampling and preparation of samples 2 7 Procedure 2 8 Expression of results 4 9 Test report 5 Table 1 Intermediate dilutions 4 Table 2 Mass of TiO 2in titanium solutions 4 Table 3 Precisi
12、on data for titanium determinations 4 Publication referred to Inside back coverii blankBS6870-2.7:1987 BSI 01-2000 1 1 Scope and field of application This International Standard specifies a 4,4-diantipyrylmethane spectrophotometric method for the determination of the titanium content of aluminium or
13、es. The method is applicable to ores containing between0,5 and 8% (m/m) of titanium dioxide. 2 Reference ISO 5725, Precision of test methods Determination of repeatability and reproducibility by inter-laboratory tests. 3 Principle Decomposition of the test portion by: a) Treatment with a mixture of
14、hydrochloric acid, nitric acid and sulfuric acid. NOTEThis method is recommended for ores containing gibbsite and/or boehmite and when the residue from the dissolution of the test portion after silica volatilization is less than 1% of the mass of the test portion; or b) Sintering with sodium peroxid
15、e followed by a brief fusion. Dissolution of the melt with sulfuric acid. NOTEThis method is recommended for ores containing diaspore and when the residue after silica volatilization for acid decomposition is greater than 1% of the mass of the test portion; or c) Fusion with sodium tetraborate/sodiu
16、m carbonate flux followed by treatment with sulfuric acid. NOTEThis method is suitable for all types of ores. Dehydration of silica, dissolution of salts, and filtration and ignition of the residue. Removal of the silica by evaporation with hydrofluoric and sulfuric acids. Fusion of the residue with
17、 sodium carbonate/sodium tetraborate flux, dissolution of the melt with sulfuric acid and addition to the main solution. Reduction of the iron with ascorbic acid; colour development with 4,4-diantipyrylmethane and measurement of the absorbance at about390nm. 4 Reagents During the analysis, use only
18、reagents of analytical reagent grade and only distilled water or water of equivalent purity. 4.1 Sodium peroxide NOTESodium peroxide should be protected against humidity and should not be used once it has begun to agglomerate. 4.2 Sodium carbonate/sodium tetraborate flux Mix 3 parts by mass of anhyd
19、rous sodium carbonate and1 part by mass of anhydrous sodium tetraborate. 4.3 Hydrofluoric acid, 40% (m/m), 201,13g/ml. 4.4 Sulfuric acid, 201,84g/ml, diluted 1 +1. 4.5 Sulfuric acid, 201,84g/ml, diluted 1 + 9. 4.6 Hydrochloric acid, 201,17g/ml, diluted 1 + 1. 4.7 Acid mixture Measure into a one-litr
20、e beaker 225ml of water and add cautiously, with mixing, 175ml of sulfuric acid ( 201,84g/ml). Cool to room temperature and add150ml of hydrochloric acid ( 201,17g/ml) and50ml of nitric acid ( 201,42g/ml). Prepare this solution fresh for each series of determinations and discard any unused solution.
21、 4.8 Ascorbic acid, 100g/l solution. Prepare this solution as required. 4.9 4,4-Diantipyrylmethane, 15g/l solution. Dissolve 15 g of 4,4-diantipyrylmethane (C 23 H 24 N 4 O 2 ) in 1l of sulfuric acid solution ( 20 1,84g/ml, diluted 1 + 49). Prepare fresh as required. 4.10 Ammonium iron(III) sulfate
22、solution. Dissolve 6g of ammonium iron(III) sulfate 24 water Fe 2 (NH 4 ) 2 (SO 4 ) 4 .24H 2 O in1litre of water containing10ml of the sulfuric acid solution (4.5). 4.11 Titanium, standard solution, corresponding to1,0g of TiO 2per litre. One of the following methods may be used: a) Weigh, to the ne
23、arest 0,001g, 0,300g of high purity (99,9%) titanium metal into a conical flask, add50ml of water and50ml of the sulfuric acid solution (4.4) and heat to dissolve the metal. Oxidize the solution until the purple colour disappears by adding, drop by drop, nitric acid solution ( 201,42g/ml, diluted 1
24、+ 4). Cool and transfer quantitatively to a500ml one-mark volumetric flask. Dilute to the mark and mix thoroughly.BS6870-2.7:1987 2 BSI 01-2000 b) Weigh, to the nearest 0,001g, 0,500g of high purity (99,9%) titanium dioxide (previously ignited in a platinum crucible at950 to1000 C for 30min and drie
25、d at105 5 C) into a250ml conical flask. Add 8g of ammonium sulfate and25ml of sulfuric acid ( 201,84g/ml). Insert a short-stemmed glass funnel in the neck of the flask and heat cautiously with frequent agitation to incipient boiling. Continue heating until complete dissolution has been effected and
26、no unattacked material remains on the walls of the flask. Cool to ambient temperature and add200ml of cold water in one portion without mixing. Mix when the addition is complete, cool, transfer quantitatively to a 500ml one-mark volumetric flask using100ml of the sulfuric acid solution(4.5) and dilu
27、te to the mark with water. NOTEWhen using a hot-plate, ensure that it is at maximum temperature so that incipient boiling is reached in the minimum time. c) Weigh, to the nearest 0,001 g, 2,215g of potassium titanium oxalate dihydrate K 2 TiO(C 2 O 4 ) 2 .2H 2 O into a 250ml conical flask; add25ml o
28、f sulfuric acid ( 1,84g/ml) and gradually heat to boiling. Boil for10min, cool well and pour the solution into300 to400ml of water. Cool and transfer quantitatively to a500ml one-mark volumetric flask. Dilute to the mark and mix thoroughly. 4.12 Titanium, standard solution corresponding to25mg of Ti
29、O 2per litre. Pipette 5,0 ml of the standard titanium solution(4.11) into a200ml one-mark volumetric flask, dilute to the mark with the sulfuric acid solution (4.5) and mix thoroughly. Prepare this solution immediately before use. 5 Apparatus Ordinary laboratory glassware and apparatus, and 5.1 Muff
30、le furnaces, adjustable from480 C to greater than1000 C. 5.2 Zirconium crucibles, approximately 40ml capacity, for sinter decomposition. 5.3 Platinum/gold alloy (95/5) crucibles or equivalent, approximately 25ml capacity, for the fusion decomposition in7.5.1.3. 5.4 Platinum crucibles, for treatment
31、of the residue in7.5.3. 5.5 Spectrophotometer, suitable for measurement of absorbance at about390nm. 5.6 Desiccator, containing phosphorus(V) oxide as desiccant. 6 Sampling and preparation of samples Laboratory samples shall be taken and crushed to pass a1504m test sieve, in accordance with the meth
32、ods specified in the relevant standards. 1) 7 Procedure 7.1 Number of determinations Carry out the analysis in duplicate and independently on each ore sample. NOTEThe expression “independently” implies a change of the person carrying out the analysis. If the same person must carry out the analysis,
33、the procedure shall be carried out at different times. 7.2 Test portion Weigh, to the nearest 0,0001g, approximately1g of test sample. 7.3 Blank test In parallel with the decomposition of the test portion, prepare a blank solution according to the method of decomposition, but omitting the test porti
34、on. When the analysis is carried out on several samples at the same time, the blank value may be represented by one test, provided that the procedure is the same and the reagents used are from the same bottles. 7.4 Check test In each run, one analysis of a certified reference material of the same ty
35、pe of ore shall be carried out in parallel, and under the same conditions, with the analysis of one ore sample. NOTEThe certified reference material should be of the same type as the sample to be analysed. Such certified reference material cannot, however, be considered as being of the same type if
36、the properties of the sample to be analysed differ from those of the certified reference material to such an extent that the analytical procedure must be changed substantially. 7.5 Determination 7.5.1 Decomposition of the test portion If the decomposition is to be based on acid attack, proceed as sp
37、ecified in7.5.1.1. If the decomposition is to be based on alkali sintering, proceed as specified in7.5.1.2. If the decomposition is to be based on fusion, proceed as specified in7.5.1.3. 1) Where no International Standards exist, the relevant standards shall be the national standards. Two Internatio
38、nal Standards on this subject are currently in preparation: ISO6137, Aluminium ores Method of sampling, and ISO6140, Aluminium ores Preparation of samples.BS6870-2.7:1987 BSI 01-2000 3 7.5.1.1 Acid decomposition Transfer the test portion (7.2) to a400ml beaker. Moisten with water and add60ml of the
39、acid mixture (4.7). Cover the beaker and heat at80 C to decompose the sample. NOTEWith samples of high iron content 15% (m/m) of Fe 2 O 3 , the initial heating should be conducted for an extended period. When the evolution of brown fumes ceases, carefully rinse the cover and wall of the beaker. Evap
40、orate the uncovered solution to dense fumes of sulfuric acid. Replace the cover and heat strongly for60min on a hot-plate set to produce in the solution a temperature of210 10 C. NOTEDetermine the temperature setting by using a separate test beaker containing a partial-immersion thermometer in a10mm
41、 depth of sulfuric acid. 7.5.1.2 Alkali sinter decomposition Transfer the test portion (7.2) to a dry zirconium crucible (5.2), add10g of the sodium peroxide (4.1) and mix intimately using a dry metal spatula. Place the crucible and contents in a muffle furnace (5.1), maintained at480 to500 C, for45
42、min. Remove the crucible and contents from the furnace and heat over a burner to melt the sinter (about30s). Continue heating the melt while swirling for a total time of2min. Allow the crucible to cool to ambient temperature (ametal block can be used to expedite this process) and place it on its sid
43、e in a400ml beaker. Cover and add cautiously at the rear of the crucible140ml of the sulfuric acid solution (4.5). Add20ml of the sulfuric acid solution (4.4) and digest to leach the contents of the crucible. Remove the crucible when the contents are completely leached and rinse well into the soluti
44、on in the beaker. Carefully rinse the cover and wall of the beaker. Evaporate the uncovered solution to dense fumes of sulfuric acid. Replace the cover and heat strongly for60min on a hot-plate set to produce in the solution a temperature of210 10 C. 7.5.1.3 Fusion decomposition Transfer the test po
45、rtion (7.2) to a dry platinum/gold crucible (5.3, see the note), add2g of the sodium carbonate/sodium tetraborate flux (4.2) and mix intimately using a dry metal spatula. Cover with a platinum lid and place in a muffle furnace (5.1), maintained at480 to500 C, for5min, then transfer to a muffle furna
46、ce, maintained at900 to950 C, for10min. NOTEA platinum crucible may be used, but care should be taken to ensure that the hot fusion mixture does not “creep” over the side of the crucible. Consequently, it would be preferable to use a larger platinum crucible, e.g.30ml. Allow the crucible to cool and
47、 place it on its side in a400ml beaker. Add40ml of water and35ml of the sulfuric acid solution (4.4), cover and digest to leach the contents of the crucible. Remove the crucible when the contents are completely leached and rinse well into the main solution. Carefully rinse the cover and wall of the
48、beaker. Evaporate the uncovered solution to dense fumes of sulfuric acid. Replace the cover and heat strongly for60min on a hot-plate set to produce in the solution a temperature of210 10 C. 7.5.2 Dissolution and filtration Cool the solution from 7.5.1.1, 7.5.1.2 or 7.5.1.3 to ambient temperature, c
49、autiously add130ml of water and heat to80 to90 C for at least40min, with stirring, to completely dissolve the salts. Filter while hot through a medium-texture filter paper, collecting the filtrate in a250ml one-mark volumetric flask. Rinse the beaker with water and, using a rubber-tipped glass rod, clean the beaker and transfer the residue quantitatively to the paper. Wash the paper and residue five times with5to10ml aliquot portions of hot water. Reserve the filtrate and washings for use in7.5.3. Retain the filt
