ISO 8658-1997 Carbonaceous materials for use in the production of aluminium - Green and calcined coke - Determination of trace elements by flame atomic absorpti.pdf

1、INTERNATIONAL STANDARD . . .: . . “St 1.j Jk p,ff.a$;:Fli: $a!,:. I d+Jfl:A .:s”;I * .r?,ls I.,* First edition 1997-04-01 Carbonaceous materials for use in the production of aluminium - Green and calcined coke - Determination of trace elements by flame atomic absorption spectroscopy Produits carbon

2、a=400net; p=iso; o=isocs; sxentral Printed in Switzerland ii INTERNATIONAL STANDARD o IS0 IS0 8658: 1997(E) Carbonaceous materials for use in the production of aluminium - Green and calcined coke - Determination of trace elements by flame atomic absorption spectroscopy 1 Scope This international Sta

3、ndard describes a method for the determination of trace elements in green and calcined coke with an ash content of not greater than 1 % (m/m) and with individual concentrations not greater than the following: Calcium Chromium Copper Iron Lead Magnesium Manganese Nickel Silicon Vanadium Zinc 0,025 %

4、(m/m) 0,005 % (m/m) 0,025 % (m/m) 0,030 % (m/m) 0,010 % (m/m) 0,010 % (m/m) 0,001 % (m/m) 0,050 % (m/m) 0,100 % (m/m) 0,100 % (m/m) 0,004 % (m/m) NOTE - A method for the determination of ash of cokes is given in IS0 80051984, Carbonaceous materials used in the production of aluminium - Green and cal

5、cined coke - Determination of ash. However, it is essential that the ash produced by that method not be used in the procedure of this tnternationat Standard because of the risk of contamination by trace elements. 2 Normative references The following standards contain provisions which, through refere

6、nce in this text, constitute provisions of this international Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the m

7、ost recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 385-l :1984, Laboratory glassware - Burettes - Part 1: General requirements. IS0 835-l :I 981, Laboratory glassware - Graduated pipettes - Part 1: General r

8、equirements. IS0 1042:1983, Laboratory glassware - One-mark volumetric f/asks. IS0 3696:1987, Water for laboratory use - Specification and test methods. IS0 63751980, Carbonaceous materials for the production of aluminium - Coke for electrodes - Sampling. 1 IS0 8658: 1997(E) 0 IS0 3 Principle A test

9、 portion sample is heated in a muffle furnace at 700 “C for 10 h and the ash produced is fused with a mixture of sodium carbonate and orthoboric acid. The melt is dissolved in dilute hydrochloric acid and the trace metal content is analysed by flame atomic absorption spectrometry. 4 Reagents Unless

10、otherwise stated, use only reagents of recognized analytical grade and water complying with grade 2 of IS0 3696. 4.1 Sodium carbonate, anhydrous. 4.2 Orthoboric acid. 4.3 Hydrochloric acid, concentrated, c(HCI) = 36 % (m/m), p = 1 ,16 g/ml. 4.4 Lanthanum chloride solution, 100 mg La/ml, atomic absor

11、ption grade, c(LaCls.7H20) = 267 g/l. 4.5 Standard calcium solution, 0,l mg/Cal. Dry calcium carbonate (reagent grade) at 110 “C + 5 “C for 1 h and cool in a desiccator containing diphosphorus pentoxide. Weigh 2,497 g Z!I 0,001 g into a 250 ml beaker. Add 50 ml of water, then, a little at a time, 50

12、 ml of concentrated hydrochloric acid (4.3). When the solution is clear, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. Using a one-mark pipette (5.8), transfer 10 ml of this solution to a 100 ml one-mark vol

13、umetric flask (5.6). Add approximately 20 ml of water and 5 ml of hydrochloric acid (4.3). Dilute to the mark with water and mix. 4.6 Standard chromium solution, 0,l mg Cr/ml. Wash, by decantation, approximately 1,2 g of chromium metal of minimum purity 99,9 % (m/m) with dilute hydrochloric acid c(H

14、CI) = 1 mol/l, then wash with water and dry in an air-circulating oven maintained at 110 “C + 5 “C for 10 min. Weigh 1 g & 0,001 g of the dried chromium into a 250 ml beaker containing about 50 ml of water. Slowly add 50 ml of concentrated hydrochloric acid (4.3). After dissolution, transfer quantit

15、atively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. Using a one-mark pipette (5.8), transfer 10 ml of this solution to a 100 ml one-mark volumetric flask (5.6). Add approximately 20 ml of water and 5 ml of concentrated hydrochlor

16、ic acid. Dilute to the mark with water and mix. Store in a polythene bottle. 4.7 Standard copper solution, 1 mg Cu/ml. Wash, by decantation, approximately 1,2 g of copper metal of minimum purity 99,9 % (m/m) with dilute nitric acid c(HNOs) = 2 mol/l, then wash with water and dry in an air-circulatin

17、g oven maintained at 110 “C rt 5 “C for 10 min. Weigh 1 g + 0,001 g of the dried copper into a 250 ml beaker containing about 25 ml of water. Slowly add 35 ml of concentrated nitric acid (p = 1,42 g/ml). After dissolution, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute

18、 to the mark with water and mix. Store in a polythene bottle. 4.8 Standard iron solution, 1 mg Fe/ml. Weigh 1 g + 0,001 g of iron of minimum purity 99,9 % (m/m) into a 250 ml beaker and add 25 ml of water. Carefully add 50 ml of concentrated hydrochloric acid (4.3). After dissolution, transfer quant

19、itatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. 2 OS0 8658:1997(E) 4.9 Standard magnesium solution, 0,Ol mg Mg/ml. Weigh 1 g f 0,001 g of magnesium of minimum purity 99,9 % (m/m) into a 250 ml beaker and add 50 ml of water.

20、 Carefully add 50 ml of concentrated hydrochloric acid (4.3). After dissolution, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. Using a one-mark pipette (5.8), transfer 10 ml of this solution to a 1 000 ml on

21、e-mark volumetric flask (5.6). Add approximately 50 ml of water and 45 ml of concentrated hydrochloric acid (4.3). Dilute to the mark with water and mix. 4.10 Standard manganese solution, 0,l mg Mn/ml. Wash, by decantation, approximately 1,2 g of manganese metal of minimum purity 99,9 % (m/m) with d

22、ilute nitric &id c(HNO$ = 2 mol/l, then wash with water and dry in an air air-circulating oven maintained at 110 “C f 5 “C for 10 min. Weigh 1 g & 0,001 g of the dried manganese into a 250 ml beaker containing about 25 ml of water. Slowly add 35 ml of concentrated nitric acid (p = 1,42 g/ml). After

23、dissolution, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. Using a one-mark pipette (5.8), transfer 10 ml of this solution to a 100 ml one-mark volumetric flask (5.6). Add approximately 50 ml of water and 3

24、ml of concentrated nitric acid (p = 1,42 g/ml). Dilute to the mark with water and mix. 4.11 Standard nickel solution, 1 mg Ni/ml. Weigh 1 g + 0,001 g of nickel of minimum purity 99,9 % (m/m) into a 250 ml beaker and add 25 ml of water. Carefully add 35 ml of concentrated nitric acid (p = 1,42 g/ml),

25、 and heat to dissolve. After dissolution, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. 4.12 Standard lead solution, 1 mg Pb/ml. Weigh 1 g f 0,001 g of lead of minimum purity 99,9 % (m/m) into a 250 ml beake

26、r and add 25 ml of water. Carefully add 35 ml of concentrated nitric acid (p = 1,42 g/ml), and heat to dissolve. After dissolution, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6). Dilute to the mark with water and mix. Store in a polythene bottle. 4.13 Standard silicon solutio

27、n, 1 mg Si/ml. Into a platinum dish or large platinum crucible, weigh 2,139 g of silica of minimum purity 99,9 % (m/m) and 6 g of anhydrous sodium carbonate (4.1), and mix well with a platinum spatula. Carefully fuse the mixture over a flame until a transparent melt is obtained. Allow to cool, add w

28、arm water, heat gently until completely dissolved and transfer quantitatively to a 400 ml PTFE beaker. Allow to cool. Dilute the solution to about 300 ml with water, transfer quantitatively to a 1 000 ml one-mark volumetric flask (5.6), dilute to the mark with water and mix. Immediately transfer thi

29、s solution to a screw-cap polythene bottle. Discard this solution after one month. 4.14 Standard vanadium solution, 1 mg V/ml. Heat vanadium(V) oxide of minimum purity 99,9 % (m/m) in a covered platinum crucible (5.9) at 500 “C X!I 10 “C for 30 min and cool in a desiccator. Weigh 1,785 g of the drie

30、d material and dissolve in a slight excess of sodium hydroxide solution c(NaOH) = 1 mol/l in a PTFE beaker, then dilute to about 250 ml with water. Carefully add, a little at a time, concentrated sulfuric acid c(O,5 HzS04) = 9 mol/l, until the solution is just acid to litmus paper, then add a furthe

31、r 5 ml. Cool to room temperature, transfer to a 1 000 ml one-mark volumetric flask (5.6), dilute to the mark with water and mix. 3 IS0 8658: 1997(E) IS0 4.15 Standard zinc solution, 0,l mg Zn/ml. Weigh 1 g + 0,001 g of zinc of minimum purity 99,9 % (m/m) into a 100 ml beaker and add 25 ml of water.

32、Carefully add 25 ml of concentrated hydrochloric acid (4.3) and heat to dissolve. After dissolution, transfer the solution quantitatively to a 1 000 ml one-mark volumetric flask (5.6), dilute to the mark with water and mix. Using a one-mark pipette (5.8), transfer 10 ml of this solution to a 100 ml

33、one-mark volumetric flask (5.6), add about 20 ml water and 5 ml of concentrated hydrochloric acid (4.3). Dilute to the mark with water and mix. 5 Apparatus Ordinary laboratory apparatus and the following are required. All glass and plastics apparatus shall be cleaned before use by washing in concent

34、rated hydrochloric acid (4.3) and rinsing with water (see clause 4, introductory paragraph). 5.1 Spectrometer, atomic absorption type, fitted with a burner fed from cylinders of acetylene, dinitrogen oxide (nitrous oxide) and compressed air. The emission wavelength and slit width shall be variable.

35、5.2 Electric muffle furnace, capable of being maintained at 700 “C + 10 “C. 5.3 Meker burner. 5.4 Sieve, with a polythene frame and polyester mesh having an aperture size in the range 500 urn to 1 000 urn. 5.5 Pestle and mortar, made from sintered alumina or from ferrous metal with a tungsten carbid

36、e liner. NOTE - Pestles and mortars made from other materials are not suitable. 5.6 One-mark volumetric flasks, complying with IS0 1042, class A. 5.7 Burettes, 25 ml, complying with IS0 385-1, class A. 5.8 One-mark pipettes, complying with IS0 835-l) class A. 5.9 Platinum crucibles, with covers, 40

37、ml capacity. To clean, place about 2,5 g of anhydrous sodium carbonate (4.1) and 1 g of orthoboric acid (4.2) into each crucible and mix. Replace the covers, then fuse the mixture over a Meker burner (5.3). Cool, dissolve the solidified melt in concentrated hydrochloric acid (4.3) and rinse with wat

38、er (see clause 4, introductory paragraph). Dry in an oven at 110 “C IL 5 “C and cool in a desiccator. 5.10 Platinum rod or spatula. 6 Sampling Prepare a crushed representative sample in accordance with IS0 6375, ensuring that the milling procedure utilizes a jaw crusher faced with tungsten carbide a

39、nd a 5 mm aperture sieve with a polythene frame and a polyester mesh (see IS0 6375). 4 0 IS0 IS0 8658: 1997(E) 7 Procedure 7.1 Preparation of the test sample Thoroughly mix the crushed sample (see clause 6) and reduce it by coning and quartering to at most 50 g. Grind the reduced sample with the pes

40、tle and mortar (5.5) to a fineness such that all the material passes through the sieve (5.4). Mix well. 7.2 Test portion Weigh 5 g f 0,001 g of the test sample into a tared platinum crucible (5.9). Place the crucible, without cover, in the cold muffle furnace (5.2). Raise the furnace temperature gra

41、dually and maintain it at 700 “C IL 10 “C for IO h. Remove the crucible and ash, allow it to cool in a desiccator and weigh as rapidly as possible. Return the crucible and ash to the furnace for 2 h and continue the cycle of heating, cooling and weighing until successive masses differ by no more tha

42、n 1 mg. 7.3 Preparation of calibration solutions 7.3.1 Calibration solutions A To each of four 600 ml beakers, add 25 g + 0,l g of anhydrous sodium carbonate (4.1) and 10 g + 0,i g of orthoboric acid (4.2) and 300 ml of water. Mix well. Cautiously add 90 ml of concentrated hydrochloric acid (4.3). O

43、nce dissolved, transfer quantitatively the contents of each beaker to one of four 1 000 ml one-mark volumetric flasks (5.6), labelled Al, A2, A3 and A4. Using clean one-mark pipettes (5.8) add the volume shown in table 1 of each standard solution to the corresponding flask. Dilute each solution to t

44、he mark with water and mix. NOTES 1 The standard silica solution should be added carefully, with swirling, to avoid the possibility of precipitation. 2 The concentrations of the relevant elements are given in table 2. Table 1 - Composition of calibration solutions A Volumes of st ard solutions Table 2 - Concentrations of elements in calibration solutions A Concentration 5