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GB/T 14849.3-2007 English PDF (GBT14849.3-2007)

GB/T 14849.3-2007 English PDF (GBT14849.3-2007)

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GB/T 14849.3-2007: Industrial silicon chemical analysis -- Part 3: Determination of calcium content

This Method specifies the method for determination of calcium content in silicon metal. This Method applies to the determination of calcium content in silicon metal. Determination range (mass fraction): 0.020%~0.30%.
GB/T ??14849.3?€?2007
GB
ICS77.120.10
H12
National Standard
of the PEOPLE Republic of China
Replacing GB/T 14849.3-1993
Methods for chemical analysis of silicon metal -
Part 3. Determination of calcium content
ISSUED ON. OCTOBER 25, 2007
IMPLEMENTED ON. APRIL 1, 2008
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Committee of Standardization Administration of PRC.
Table of Contents
Foreword ... 3
Method I Flame atomic absorption spectrometry ... 5
1 Scope ... 5
2 Method summary ... 5
3 Reagents ... 5
4 Instruments ... 6
5 Test sample ... 6
6 Analysis steps ... 6
7 Calculation of the analysis results ... 8
8 Precision ... 8
9 Quality assurance and control ... 9
Method II Chlorophosphonazo I spectrophotometric method ... 9
10 Scope ... 9
11 Method summary ... 9
12 Reagents ... 9
13 Instruments ... 10
14 Test sample ... 10
15 Analytical steps ... 11
16 Calculation of the analysis results ... 12
17 Precision ... 12
18 Quality assurance and control ... 13
Foreword
GB/T14849 Methods for Chemical Analysis of Silicon Metal is divided into 4 parts. ?€? Part 1. Determination of iron content - 1, 10-phenanthroline spectrophotometric method;
?€? Part 2. Determination of aluminum content - chrome azurol-S spectrophotometric method;
?€? Part 3. Determination of calcium content - flame atomic absorption spectrometry, chlorophosphonazo I spectrophotometric method;
?€? Part 4. Inductively coupled plasma-atomic emission spectrometry to determine element content.
This Part is Part 3.
Method I and Method II of this Part are flame atomic absorption spectrometry and chlorophosphonazo-I spectrophotometric method respectively.
If there is dispute to the analysis results, Method I is the arbitration analysis method. Method I of this Part is an amendment of GB/T 14849.3-1993 Methods for chemical analysis of silicon metal. Determination of calcium content. To reflect the coordination of standards, and make the standards of analysis method and product match well, the determination range (of mass fraction) of these 2 methods in this Part is changed from 0.05%-1.20% to 0.02%-0.30%. Meanwhile, the clauses of ?€?repeatability?€? and ?€?quality assurance and control?€? are added.
This Part was proposed by China Nonferrous Metals Industry Association. This Part shall be under the jurisdiction of the National Technical Committee on Nonferrous Metals of Standardization.
This Part was responsibly drafted by Fushun Aluminum Co., Ltd.
Method I in this Part was drafted by Zhengzhou Research Institute of CHALCO. Method II in this Part was drafted by Fushun Aluminum Co., Ltd.
Main drafters of Method I in this Part. Zhang Weihua, Zhang Shuchao, Zheng Wenliang, and Shi Lei.
Main drafters of Method II in this Part. Yuan Jianchang, Yang Yuhong, Ji Chunlei, and Yang Limei.
The previous version of the standard replaced by this Part is as follows. ?€? GB/T 14849.3-1993.
Methods for chemical analysis of silicon metal - Part 3.
Determination of calcium content
Method??I Flame??atomic??absorption??spectrometry
1 Scope
This Method specifies the method for determination of calcium content in silicon metal. This Method applies to the determination of calcium content in silicon metal. Determination range (mass fraction). 0.020%~0.30%.
2 Method??summary
The specimen is decomposed with hydrofluoric acid and nitric acid. Perchloric acid?€?s smoking removes silicon, fluorine, etc. And the residue is dissolved with hydrochloric acid. Lanthanum salt is used to control the interference of aluminum. Determine the absorbance of calcium by air-acetylene flame, at flame atomic absorption spectrometry wavelength of 422.7nm.
3 Reagents
3.1 Perchloric acid (??1.67g/L).
3.2 Hydrogen Chloride (??1.14g/L).
3.3 Nitric acid (1+1).
3.4 Hydrochloric acid (1+1).
3.5 Lanthanum salt solution (10g/L). WEIGH 5.00g of lanthanum oxide and PTU put into 250mL beaker. ADD 15mL of hydrochloric acid (3.4). DISSOLE by slightly heating. COOL to the room temperature. PUT into 500mL volumetric flask. DILUTE with water to the scale. MIX evenly.
3.6 Calcium standard storage solution (500??g/mL). WEIGH 0.6243g of standard calcium carbonate, which has been pre-dried at 105??C and cooled to the room temperature in dryer, INTO 300mL beaker. ADD about 20mL water. Add hydrochloric acid (3.4) drop-by-drop until completely dissolved, and with excessive 10mL. HEAT to boil so as to remove carbon dioxide. COOL it to the room temperature. PIPETTE into 500mL volumetric flask. DILUTE with water to the scale. MIX evenly. 1mL of this solution contains 12.4 Hydrochloric acid (1+1).
12.5 Triethanolamine (1+3). STORE in the polyethylene bottle.
12.6 1,10-phenanthroline ethanol solution (4g/L). WEIGH 4.0g of 1,10-phenanthroline (C12H8N2?€?H2O) and PUT into 1000mL volumetric flask. After adding ethanol to dissolve, USE ethanol to dilute to the scale. MIX evenly.
12.7 Acetate acetone (1???40).
12.8 Buffer solution. WEIGH 21.00g of borax (Na2B4O7?€?10H2O) and 4.00g of sodium hydroxide (Guaranteed reagent). After using water to dissolve, DILUTE to 1000mL.The pH value of this solution is 10.5. STORE in the polyethylene bottle.
12.9 Chlorophosphonazo-I (C16H18O14N2S2PCl) solution (1.0g/L).
12.10 EGTA-Pb solution (0.02mol/L). WEIGH 1.90g of ethylene glycol tetraacetic acid (EGTA). PUT in a beaker. ADD about 100mL of water. HEAT it. ADD sodium hydroxide (1mol/L) drop-by-drop to help dissolution. And ADJUST to neutral. TAKE another 1.53g of lead chloride. ADD about 100mL of water. After dissolved by heating, MIX the 2 solutions while they are hot. ADJUST to neutral. After cooling, USE water to dilute to 250mL. MIX evenly.
12.11 Calcium standard storage solution. WEIGH 2.4970g of standard calcium carbonate, which has been pre-dried at 105??C and has been cooled to the room temperature in dryer, INTO a beaker. ADD about 200mL of water. Then ADD hydrochloric acid (12.4) drop-by-drop until completely dissolved, and an excessive 20mL is added. HEAT to boiling so as to remove the carbon dioxide. COOL it down. PIPETTE into 1000mL volumetric flask. USE water to dilute to the scale. MIX evenly. 1ml of this solution contains 1mg of calcium.
12.12 Calcium standard solution. PIPETTE 10.00mL of calcium standard storage solution (12.11) in 1000mL volumetric flask. USE water to dilute to the scale. MIX evenly. 1ml of this solution contains 0.2mg of chromium.
13 Instruments
13.1 Spectrophotometer.
13.2 Acidimeter.
14??Test??sample
The test sample shall all pass through 0.149mm standard sieve. And USE magnet to remove iron powder.
absorbance of reagent as ordinate to draw the working curve.
USE iron mass of calcium as the abscissa; the absorbance after the blank absorbance of reagent is subtracted AS ordinate; DRAW the working curve.
16??Calculation??of??the??analysis??results
CALCULATE mass fraction of calcium (w) by Formula (2), values expressed in %. Where.
m1 ?€? Mass of calcium obtained from the working curve, in unit of ??g (??g); V0 ?€? Total volume of test solution, in unit of mL (mL);
m0 ?€? Mass of the specimen, in unit of g (g);
V1 ?€? Volume of test solution taken, in unit of mL (mL).
17??Precision
17.1 Repeatability
Under the repeatability condition, within the range of average value given as follows, for the determination values obtained from 2 independent test results, the absolute values of these 2 test results shall not exceed repeatability limit (r). The probability of exceeding repeatability limit (r) is no more than 5%. The repeatability limit (r) is obtained by linear interpolation or extrapolation according to the data in Table 4.
Table 4
Mass fraction of calcium /% Repeatability limit r/%
0.022 0.003
0.097 0.006
0.207 0.018
17.2 Allowable difference
The difference of analysis results among laboratories shall not exceed the allowable difference listed in Table 5.
Table 5
Mass fraction of calcium /% Allowable difference /%
0.020~0.080 0.005
>0.080~0.150 0.010
>0.150~0.300 0.020
18??Quality??assurance??and??...

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