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GB/T 3521-2023 English PDF (GB/T 3521-2008, GB/T 3521-1995)

GB/T 3521-2023_English: PDF (GB/T3521-2023)
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GB/T 3521-2023English380 Add to Cart 0--9 seconds. Auto-delivery Methods for chemical analysis of graphite Valid GB/T 3521-2023
GB/T 3521-2008English125 Add to Cart 0--9 seconds. Auto-delivery Method for chemical analysis of graphite Obsolete GB/T 3521-2008
GB/T 3521-1995English399 Add to Cart 3 days [Need to translate] Method for chemical analysis of graphite Obsolete GB/T 3521-1995
GB 3521-1983English279 Add to Cart 3 days [Need to translate] Method for chemical analysis of graphite Obsolete GB 3521-1983


BASIC DATA
Standard ID GB/T 3521-2023 (GB/T3521-2023)
Description (Translated English) Methods for chemical analysis of graphite
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard Q51
Classification of International Standard 73.080
Word Count Estimation 22,211
Date of Issue 2023-12-28
Date of Implementation 2024-07-01
Older Standard (superseded by this standard) GB/T 3521-2008
Drafting Organization Suzhou Sinoma Non-metallic Minerals Industrial Design and Research Institute Co., Ltd., China Building Materials Industrial Geological Exploration Center Yunnan Corps, Xianyang Non-metallic Minerals Research and Design Institute Co., Ltd., China National Building Materials Heilongjiang Graphite New Materials Co., Ltd., Guangdong Bangpu Recycling Technology Co., Ltd. Shanghai Shanshan New Materials Co., Ltd., Jiangxi Ningxin New Materials Co., Ltd., Guangdong Siquan New Materials Co., Ltd., Mining and Metallurgy Technology Group Co., Ltd., Nuclear Industry 203 Research Institute, China Building Materials Industrial Geological Exploration Center Xinjiang Corps , Shenzhen Shijin Technology Co., Ltd., Qingdao Luowei New Materials Co., Ltd., Qingdao Huateng Graphite Technology Co., Ltd., Hebei Kuntian New Energy Co., Ltd., Hebei Zhengda Friction Braking Materials Co., Ltd., Chenzhou Product Quality Supervision Inspection Institute, Jiangxi Zichen Technology Co., Ltd.
Administrative Organization National Technical Committee on Standardization of Non-metallic Mineral Products and Products (SAC/TC 406)
Proposing organization China Building Materials Federation
Issuing agency(ies) State Administration for Market Regulation, National Standardization Administration

BASIC DATA
Standard ID GB/T 3521-2008 (GB/T3521-2008)
Description (Translated English) Method for chemical analysis of graphite
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard Q51
Classification of International Standard 73.080
Word Count Estimation 10,193
Date of Issue 2008-08-20
Date of Implementation 2009-04-01
Older Standard (superseded by this standard) GB/T 3521-1995
Quoted Standard GB/T 3518; GB/T 3519
Drafting Organization Xianyang Institute of Non-metallic Minerals
Administrative Organization National Non-metallic mineral products and products for Standardization Technical Committee
Regulation (derived from) National Standard Approval Announcement 2008 No.14 (Total No.127)
Proposing organization China Building Materials Federation
Issuing agency(ies) Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China
Summary This standard specifies the graphite product moisture, volatile, sulfur content and methods of analysis of acid-soluble iron content, fixed carbon content, ash. This standard applies to natural graphite products.

BASIC DATA
Standard ID GB/T 3521-1995 (GB/T3521-1995)
Description (Translated English) Method for chemical analysis of graphite
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard D53
Classification of International Standard 73.08
Word Count Estimation 10,153
Date of Issue 1995/2/7
Date of Implementation 1995/10/1
Older Standard (superseded by this standard) GB 3521-1983
Regulation (derived from) Announcement of Newly Approved National Standards 2008 No. 14 (No. 127 overall)
Proposing organization State Building Materials Industry Bureau
Issuing agency(ies) State Bureau of Technical Supervision


GB/T 3521-2023 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 73.080 CCS Q 51 Replacing GB/T 3521-2008 Methods for Chemical Analysis of Graphite ISSUED ON: DECEMBER 28, 2023 IMPLEMENTED ON: JULY 1, 2024 Issued by: State Administration for Market Regulation; Standardization Administration of the People’s Republic of China. Table of Contents Foreword ... 3 1 Scope ... 5 2 Normative References ... 5 3 Terms and Definitions ... 5 4 General Stipulations ... 5 5 Determination of Moisture ... 6 6 Determination of Volatile Matter ... 7 7 Determination of Ash Content ... 10 8 Determination of Fixed Carbon Content ... 11 9 Determination of Sulfur Content ... 14 10 Determination of Acid-soluble Iron ... 21 11 Determination of Iron Content ... 26 Methods for Chemical Analysis of Graphite WARNING: personnel using this document needs to have practical experience in laboratory work. This document does not point out all safety, health and environmental protection issues related to its use. It is the users’ responsibility to take appropriate safety, health and environmental protection measures, and ensure compliance with relevant national laws and regulations. 1 Scope This document describes methods for the analysis of moisture, volatile matter, ash content, fixed carbon content, sulfur content, acid-soluble iron content and iron content of graphite products. This document is applicable to the chemical analysis of natural graphite products. 2 Normative References The contents of the following documents constitute indispensable clauses of this document through the normative references in the text. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 6679 General Rules for Sampling Solid Chemical Products GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgement of Limiting Values 3 Terms and Definitions This document does not have terms or definitions that need to be defined. 4 General Stipulations 4.1 Samples for chemical analysis obtained in accordance with the sampling method specified in GB/T 6679 shall be packed in plastic bags or ground-mouth bottles, and the sampling size shall be no less than 50 g. 4.2 Except for moisture determination, all other analysis items shall be analyzed after the specimens are baked to a constant weight at 105 C ~ 110 C. 4.3 The weighing of high, medium and low carbon specimens shall be accurate to 0.1 mg, and when constant weight is required, the difference between the two weighing values shall not be greater than 0.3 mg. The weighing of high-purity graphite specimens shall be accurate to 0.02 mg, and when constant weight is required, the difference between the two weighing values shall not be greater than 0.05 mg. 4.4 Each analysis item shall be determined at least twice in parallel. Take the arithmetic mean of two parallel determination results as the analysis result. 4.5 The calculation results of high-purity graphite are rounded to four decimal places in accordance with GB/T 8170, and the calculation results of other items are rounded to two decimal places in accordance with GB/T 8170. 4.6 Unless otherwise stated, the water used in this Method shall not be lower than Grade-3 water specified in GB/T 6682. 4.7 The concentration of a solution is expressed as molar concentration or mass concentration. Others, such as: (1 + 1), (1 + 2) and (m + n), etc. refer to the ratio of solute volume to water volume. Unless otherwise specified, the solutions used are all aqueous solutions. 4.8 Unless otherwise stated, the reagents used in this Method are only those confirmed to be of analytical purity or guaranteed purity; the reagents used for calibration are only those confirmed to be primary reagents or of spectral purity or high purity; the acid and ammonia water used are only confirmed concentrated acid or concentrated ammonia water. 5 Determination of Moisture 5.1 Instruments, Equipment and Materials 5.1.1 Electric drying oven: room temperature to 200 C, with a temperature control accuracy of  2 C. 5.1.2 Analytical balance: with an accuracy not lower than 0.1 mg. 5.1.3 Ground-mouth weighing bottle: 20 mL. 5.2 Analytical Procedures Accurately weigh-take 2 g ~ 5 g of undried specimen, accurate to 0.1 mg, and record it as m0. Put it into a ground-mouth weighing bottle that has been dried to a constant weight, slightly open the lid, and place it in an oven at 105 C ~ 110 C. After drying for 2 hours, take out the ground-mouth weighing bottle and properly put on the lid of the weighing bottle. Place it in a desiccator to cool for 30 minutes, weigh it and record it as m. Repeat this, until reaching a constant weight. 5.3 Result Calculation 8.2.2.4 Graphite standard sample: graphite mineral composition analysis standard substance, GBW 03118, GBW 03119, GBW 03120. 8.2.2.5 Oxygen: with a purity not less than 99.5%. 8.2.3 Instruments, equipment and materials 8.2.3.1 High-frequency infrared carbon and sulfur analyzer: carbon determination accuracy is not less than 0.0001%. 8.2.3.2 Analytical balance: with an accuracy not lower than 0.1 mg. 8.2.3.3 Box-type resistance furnace: the maximum temperature is not lower than 1,200 C, with a temperature control accuracy of  10 C. 8.2.3.4 Temperature controllable electric heating plate: room temperature to 300 C, with a temperature control accuracy of  2 C. 8.2.3.5 Electric drying oven: room temperature to 300 C, with a temperature control accuracy of  2 C. 8.2.3.6 Desiccator: equipped with color-changing silica gel. 8.2.3.7 Porcelain crucible. 8.2.4 Porcelain crucible treatment Burn the porcelain crucible at 1,000 C for 2 hours, then, place it in a desiccator to cool and reserve it for later use. 8.2.5 Sample treatment Weigh-take 10.00 g (accurate to 0.1 mg) of dried specimen and place it in a porcelain crucible that has been subjected to the burning treatment; slowly dropwise add excess hydrochloric acid solution (1 + 1) to thoroughly acidify the sample. Then, on a temperature controllable electric heating plate with a temperature below 150 C, slowly dry and cool it. Dropwise add water in several times, wash the specimen, until it becomes neutral, then, move it into the box-type resistance furnace. Raise the temperature from room temperature to 350 C, leave a gap in the furnace door, and thoroughly burn for 2 hours. Then, take it out and cool it for later use. 8.2.6 Analytical procedures 8.2.6.1 Calibration test Actuate the instrument and pre-heat for 30 minutes. Adjust the instrument to determine the fixed carbon state. Turn on the oxygen; in accordance with the sample to be determined, select the standard substance and perform system calibration, until the repeatability of the determination results reaches the uncertainty range required by the graphite standard sample. Thus, the system 5---high-temperature porcelain tube (1,300 C); 6---tubular electric furnace (1,300 C); 7---porcelain boat; 8---burette; 9, 10---sulfur determination cups. Figure 2 -- Sulfur Determination Device 9.1.4 Analytical procedures 9.1.4.1 Device tightness inspection: rapidly raise the furnace temperature to 1,200 C ~ 1,250 C, introduce oxygen or air, adjust the flow rate to 0.7 L/min ~ 0.8 L/min, and check whether there is any air leakage in the device before conducting the test. 9.1.4.2 Specimen determination: add 2/3 volume of hydrochloric acid solution (3 + 197) into the sulfur determination cup, add 10 mL of starch-potassium iodide solution, and dropwise add potassium iodate standard solution to make the solution in the sulfur determination cup turn light blue. Use the same method to prepare a reference solution for judging the end point. Ventilate for 4 minutes ~ 5 minutes. If the blue color of the solution in the sulfur determination cup disappears, then, dropwise add potassium iodate standard solution, until the blue color does not disappear. Accurately weigh-take 0.2 g ~ 1.0 g of dried specimen (depending on the sulfur content), accurate to 0.1 mg, and record it as m12. Put it into the burned porcelain boat, use a sulfur-free metal hook to quickly push the porcelain boat into the combustion tube, and immediately block the mouth of the tube. At 1,200 C ~ 1,250 C, perform ventilation combustion. The ventilation rate should be 80 ~ 100 bubbles per minute. When the gas enters the lower part of the sulfur determination cup, which makes the blue color disappear, immediately dropwise add the potassium iodate standard solution. The dropwise adding speed shall be such that the solution in the absorber maintains the light blue color of the original blank, until the light blue color of the solution remains constant for 1 minute ~ 2 minutes, which is the end point. 9.1.4.3 Determination of correction coefficient: in accordance with the sample content, select a coke standard sample with an appropriate sulfur content; accurately weigh-take 0.1 g ~ 1.0 g of standard sample, accurate to 0.1 mg, and record it as m11. In the burned porcelain boat, follow the subsequent steps in 9.1.4.2. 9.1.5 Result calculation 9.1.5.1 The correction coefficient (F) is calculated in accordance with Formula (7): Where, 9.2.2.1 Graphite standard sample: graphite mineral composition analysis standard substance, GBW 03118, GBW 03119, GBW 03120. 9.2.2.2 Tungsten trioxide: analytically pure. 9.2.2.3 Sodium hydroxide: analytically pure. 9.2.2.4 Potassium iodide: analytically pure. 9.2.2.5 Potassium bromide: analytically pure. 9.2.2.6 Glacial acetic acid: analytically pure. 9.2.2.7 Electrolyte: weigh-take 5.0 g each of potassium iodide and potassium bromide, dissolve it in 250 mL ~ 300 mL of distilled water, and add 10 mL of glacial acetic acid to the solution. 9.2.3 Instruments, equipment and materials 9.2.3.1 Analytical balance: with an accuracy not lower than 0.1 mg. 9.2.3.2 Coal sample: with a particle size less than 0.3 mm, not less than 100 mg. 9.2.3.3 Color-changing silica gel. 9.2.3.4 Porcelain boat: bisque or corundum product; the length of the sample-holding part is about 60 mm, and the temperature resistance is greater than 1,200 C. 9.2.3.5 Coulomb sulfur meter: it mainly consists of the following parts. a) Tubular high-temperature furnace: it can be heated to above 1,200 C and has a high- temperature constant-temperature zone at 1,150 C of at least 70 mm long. It is equipped with a platinum-rhodium-platinum thermocouple temperature measurement and control device, and the furnace is equipped with a reducing diameter combustion tube with heat resistance greater than 1,300 C. b) Electrolytic cell and electromagnetic stirrer: the electrolytic cell is 120 mm ~ 180 mm high, with a capacity of not less than 400 mL. It contains a platinum electrolytic electrode pair with an area of 150 mm2 and a platinum indicator electrode pair with an area of approximately 15 mm2. The response time of the indicator electrode shall be less than 1 s, and the electromagnetic stirrer speed is about 500 r/min and continuously adjustable. c) Coulomb integrator: the integral linear error within the range of electrolytic current 0 mA ~ 350 mA shall be less than 0.1% and equipped with a 4 ~ 6 digits digital display or printer. d) Sample delivery program controller: it can move forward and backward in accordance with the prescribed procedures. e) Air supply and purification device: it consists of electromagnetic pump and purification pipe. The air supply volume is about 1,500 mL/min, and the gas extraction volume is about 1,000 mL/min. The purification tube is filled with sodium hydroxide and color-changing silica gel. 9.2.4 Analytical procedures 9.2.4.1 Turn on the power of the Coulomb sulfur meter and adjust the temperature control device to control the furnace temperature at around 1,150 C. 9.2.4.2 Add 300 mL of electrolyte to the electrolytic cell and turn on the magnetic stirrer. 9.2.4.3 Turn on the electromagnetic pump, adjust the air flow to 1,000 mL/min, and check the air tightness. 9.2.4.4 Coal sample test: take about 50 mg of coal sample and put it into a porcelain boat that has been pre-burned at 800 C. Use a thin layer of tungsten trioxide to cover the surface and put it into he high-temperature part of the tubular electric furnace. After 5 minutes, the porcelain boat automatically returns. If the mass of sulfur on the automatic sulfur meter shows zero, a re- determination shall be performed, until it is not zero. 9.2.4.5 Graphite standard sample test: weigh-take 50 mg of the graphite standard sample, accurate to 0.1 mg, put it into a porcelain boat, and use a thin layer of tungsten trioxide to cover the surface of the graphite standard sample. Then, put it into the porcelain boat at the entrance of the tubular electric furnace, and press the “START” button. The graphite standard sample is automatically sent to the high-temperature part of the tubular electric furnace by a nickel- chromium wire hook. After 5 minutes, the porcelain boat automatically returns. Record the displayed sulfur mass (mg). If it is inconsistent with the graphite standard sample, the coefficient can be corrected. 9.2.4.6 Weigh-take 50 mg of specimen, accurate to 0.1 mg and record it as m14. Put it into a porcelain boat that has been pre-burned at 800 C and use a thin layer of tungsten trioxide to cover the surface. Then, put the porcelain boat into the entrance of the tubular electric furnace, press the “START” button, and record the displayed sulfur mass as m13. 9.2.4.7 At the end of the test, successively close the straight-through valve, magnetic stirrer and electromagnetic pump, release the electrolyte (reusable), clean the electrolytic cell and turn off the power supply. 9.2.5 Result calculation The sulfur content (w8) in the specimen is calculated in accordance with Formula (9): Where, 10.1.2.4 Sulfosalicylic acid solution (200 g/L). 10.1.2.5 Ammonium thiocyanate solution (100 g/L). 10.1.2.6 Iron standard stock solution [ρ(Fe) = 1.00 mg/mL]: accurately weigh-take 1.4297 g of high-purity (or spectrally pure) iron trioxide that has been dried at 105 C ~ 110 C for 2 hours and cooled to room temperature, add 50 mL of hydrochloric acid solution (1 + 1), dissolve it, then, transfer to a 1,000 mL volumetric flask. Use water to dilute to the scale and shake it well. 10.1.2.7 Iron standard solution [ρ(Fe) = 0.04 mg/mL]: accurately draw-take 10.0 mL of the iron standard stock solution (10.1.2.6) and place it in a 250 mL volumetric flask. Use water to dilute to the scale and shake it well. 10.1.3 Instruments and equipment 10.1.3.1 Analytical balance: with an accuracy not lower than 0.1 mg. 10.1.3.2 Electric drying oven: room temperature to 200 C, with a temperature control accuracy of  2 C. 10.1.3.3 Spectrophotometer: with a 1 cm cuvette, and a wavelength range of 300 nm ~ 800 nm. 10.1.4 Analytical procedures 10.1.4.1 Drawing of standard curve Take 0.00 mL, 1.00 mL, 3.00 mL, 5.00 mL, 7.00 mL, 10.00 mL, 15.00 mL and 20.00 mL of the iron standard solution (10.1.2.7), respectively place them in a set of 100 mL volumetric flasks. Use water to dilute to about 50 mL, add 2 mL of sulfosalicylic acid solution (200 g/L), and shake it well. Dropwise add ammonia solution (1 + 1) to make the color of the solution change from purple to yellow with an excess of 4 mL, use water to dilute to the scale and shake it well. Leave it for 10 minutes. Use a 1 cm cuvette, use water as a reference, at a wavelength of 420 nm, determine the absorbance of the solution. Take iron content as the x-coordinate and the absorbance as the y-coordinate to draw a working curve. 10.1.4.2 Determination 10.1.4.2.1 Accurately weigh-take 0.5 g [when the iron content (mass fraction) is lower than 0.5%, take 1 g ~ 3 g] of dried specimen, accurate to 0.1 mg, and record it as the mass of the specimen. Place it in a 150 mL beaker and use a small amount of water to wet the specimen. Add 25 mL of concentrated hydrochloric acid, stir it, until the specimen is completely immersed in the acid. Use a watch glass to cover it, place it on the electric heating plate, keep it slightly boiling for 20 minutes. Then, remove it, and use water to wash the watch glass and cup wall. Let it slightly cool, then, use a medium-speed qualitative filter paper to filter it into a 250 mL volumetric flask. Use hot water to wash it, until there is no iron ion (check with ammonium thiocyanate solution, and there shall be no red color). After cooling, dilute it to the scale and shake it well. This is the specimen solution. and the temperature control accuracy is  10 C. 11.1.3.4 Platinum crucible: with a volume of not less than 30 mL. 11.1.4 Analytical procedures 11.1.4.1 Drawing of standard curve Take 0.00 mL, 0.50 mL, 1.00 mL, 1.50 mL, 2.00 mL, 2.50 mL, 3.00 mL, 4.00 mL and 5.00 mL of iron standard solution (11.1.2.6), and respectively place them in a set of 100 mL volumetric flasks. Add water to dilute to about 50 mL, add 10 mL of sulfosalicylic acid solution (100 g/L), use ammonia solution (1 + 1) to neutralize it, until the test solution just turns yellow, and with an excess of 2 mL. Use water to dilute it to the scale and shake it well. At a wavelength of 420 nm, determine the absorbance. Select a 1 cm cuvette, use water as a reference, at a wavelength of 420 nm, determine the absorbance of the solution. Take iron content as the x-coordinate and absorbance as the y-coordinate to draw a working curve. 11.1.4.2 Determination 11.1.4.2.1 Weigh-take 1 g ~ 3 g (accurate to 0.1 mg) of specimen, place it in a platinum crucible, and record it as the mass of the specimen. Burn it at 950 C ~ 1,000 C to remove all carbon, add 3 g ~ 4 g of anhydrous sodium carbonate and mix it well. Then, use 1 g of anhydrous sodium carbonate to cover it and put it into a high-temperature furnace. At 950 C ~ 1,000 C, melt it for 20 minutes, then, take it out to cool. Use a filter paper to wipe the outer wall of the crucible, put it into a 250 mL beaker containing 100 mL of boiling water. Use a watch glass to cover it, cool for 5 minutes, and carefully dropwise add hydrochloric acid solution (1 + 1) to dissolve the melt. After complete dissolution, place it on an electric furnace and boil for 5 minutes, then, cool and reserve it for later use. Transfer the above-mentioned to a 250 mL volumetric flask, dilute to the scale and mix it well. This is the specimen solution. 11.1.4.2.2 Dispense 5 mL ~ 25 mL of specimen solution into a 100 mL volumetric flask, add water to dilute to about 50 mL, add 10 mL of sulfosalicylic acid solution (100 g/L) and shake it well. Follow 11.1.4.1 for the subsequent steps. Meanwhile, carry out a blank test. 11.1.5 Result calculation The iron content (w11) is calculated in accordance with Formula (13): Where, w11---the iron content (mass fraction); ρ3---the mass concentration of iron in the solution to be tested obtained from the standard series curve (or direct reading of the concentration), expressed in (g); 11.3 Inductively Coupled Plasma Optical Emission Spectrometry 11.3.1 Method summary When a completely dissolved specimen is introduced into the inductively coupled plasma torch, the iron element in the solution is excited by high temperature and emits characteristic spectral lines. The intensity of the characteristic spectral lines has a corresponding functional relationship with the content of the element. By determining the intensity of the characteristic spectral lines, determine the element content. 11.3.2 Reagent Hydrochloric acid solution (1 + 1). 11.3.3 Instruments, equipment and materials 11.3.3.1 Analytical balance: with an accuracy not lower than 0.1 mg. 11.3.3.2 Inductively coupled plasma optical emission spectrometer. 11.3.4 Analytical procedures 11.3.4.1 Preparation of working curve series of solutions Accurately transfer-take 0.00 mL, 0.50 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL and 6.00 mL of iron standard solution (11.1.2.6), respectively place them into seven 100 mL volumetric flasks, add 4 mL of hydrochloric acid solution (1 + 1), use water to dilute to the scale and shake them well. 11.3.4.2 Preparation of test solution Dispense 5 mL ~ 10 mL of the specimen solution in 11.1.4.2.1 and place it in a 100 mL volumetric flask. Add 4 mL of hydrochloric acid solution (1 + 1), use water to dilute to the scale and shake it well. Meanwhile, carry out a blank test. 11.3.5 Determination On the inductively coupled plasma emission spectrometer, in accordance with the instrument model, set the required working parameters (use a high-salt atomizer). Successively and respectively determine the emission spectral intensity of the blank solution, working curve series of solutions and test solution preparation, and draw a working curve. From the working curve, obtain the mass concentration of iron element or use direct reading of the mass concentration of iron element. 11.3.6 Result calculation The iron content (w13) is calculated in accordance with Formula (15): ......


GB/T 3521-2008 NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 73.080 Q 51 Replacing GB/T 3521-1995 Method for chemical analysis of graphite ISSUED ON: AUGUST 20, 2008 IMPLEMENTED ON: APRIL 01, 2009 Issued by: General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of the People’s Republic of China. Table of Contents Foreword ... 3  1 Scope ... 5  2 Normative references ... 5  3 General provisions ... 5  4 Test method ... 6  5 Allowable difference ... 17  Method for chemical analysis of graphite 1 Scope This Standard specifies the analysis methods of graphite products for moisture, volatile content, ash, fixed carbon content, sulfur content, and acid-soluble iron content. This Standard applies to natural graphite products. 2 Normative references The terms in the following documents become the terms of this Standard by reference to this Standard. For dated references, all subsequent amendments (not including errata content) or revisions do not apply to this standard. However, parties to agreements that are based on this Standard are encouraged to study whether the latest versions of these documents can be used. For undated references, the latest edition applies to this Standard. GB/T 3518, Flake graphite GB/T 3519, Amorphous graphite 3 General provisions 3.1 The samples for chemical analysis, which are obtained in accordance with the sampling methods that are specified in GB/T 3518 and GB/T 3519, shall be packed in plastic bags or ground-mouth bottles; the sample size shall not be less than 50 g. 3.2 Except for the determination of moisture, all other analysis items shall be analyzed after the sample is dried to constant weight at 105 °C ~ 110 °C. 3.3 The weighing of high, medium and low carbon samples shall be accurate to 0.1 mg. When constant weight is required, the difference between the two times of weighing shall not be greater than 0.3 mg. The weighing of high-purity graphite samples shall be accurate to 0.02 mg; the constant weight of the difference between two times of weighing shall not be greater than 0.05 mg. 3.4 For each analysis item, the parallel determination must be performed. For the analysis of sulfur, a blank test shall be performed. 3.5 The calculation results of high-purity graphite are expressed to three decimal places; the calculation results of the remaining items are expressed to two decimal places. 3.6 For the water that is used in this method, unless otherwise stated, only use confirmed distilled water or deionized water or water of considerable purity in the analysis. 3.7 The concentration of the solution is the molar concentration or the mass of solute in 1 L of solution (g/L). For example, (1 + 1), (1 + 2), (m + n) refer to the ratio of the volume of solute to the volume of water. Unless otherwise specified, the used solutions are all aqueous solutions. 3.8 Unless otherwise specified, in the analysis, only use the reagents that are confirmed as analytical reagents or guaranteed reagents; for the reagents that are used for calibration, only use the reagents that are confirmed as primary reagents, or spectrally pure, high-purity reagents. Unless otherwise stated, for acids and ammonia that are used in the analysis, only use confirmed concentrated acids or alkalis. 4 Test method 4.1 Moisture determination method 4.1.1 Method summary Dry the sample at 105 °C ~ 110 °C, to volatilize the adhered water; calculate the percentage content of adhered water according to the volatile content. 4.1.2 Instruments 4.1.2.1 Oven or other instruments of equivalent performance: the working temperature is 105 °C ~ 110 °C. 4.1.2.2 Balance: the sensitivity is 0.1 mg. 4.1.3 Analysis procedures Accurately weigh 1 g ~ 2 g of undried samples, to the nearest 0.1 mg. Put it into a grinding-mouth weighing bottle that has been dried to a constant weight; put it in an oven at 105 °C ~ 110 °C. Open the lid; bake for 1 h ~ 2 h; take out the weighing bottle; cover it; put it in a desiccator to cool to room temperature; weigh. Put it into the oven to bake for 30 minutes; take it out; cool; weigh. Repeat this process until constant weight. It is subject to the last data. 4.1.4 Result calculation 4.3.2.3 Pyrolysis furnace: a square tube furnace that is equipped with a gas system (see Figure 1), or a box high-temperature furnace. 4.3.2.4 Sample boat: the quartz boat is used for the square tube furnace; the square porcelain boat is used for the box high-temperature furnace; the loading capacity is 0.5 g ~ 3 g. 4.3.3 Analysis procedures Accurately weigh 0.3 g ~ 1 g (for high-purity graphite, weigh 1 g ~ 2 g) of dried sample, to the nearest 0.1 mg (to the nearest 0.01 mg for high-purity graphite); place it in a sample boat of constant weight; put the sample boat into a pyrolysis furnace that has been heated to 900 °C ~ 1 000 °C; after preheating for 1 minute, push it into the high temperature zone; introduce oxygen or air flow; burn to no black spots; take it out and place it in a desiccator after cooling; cool to room temperature; weigh. Then, put it into the pyrolysis furnace and burn for 30 min (10 min when oxygen flow is introduced); take it out; cool; weigh. Repeat this process until constant weight. 4.3.4 Result calculation The ash is based on the mass fraction w3; the value is expressed as 10-2 or in %; it is calculated according to Formula (3): Where: m -- the mass of the dried sample before burning, in grams (g); m2 -- the mass of the residue after burning, in grams (g). 4.4 Fixed carbon content determination method -- indirect carbon determination method 4.4.1 Method summary The indirect carbon determination method is also called the combustion method, that is, after measuring the volatile content and ash content of the sample, subtract them from the total amount, and the difference is the fixed carbon content. This method applies to graphite products whose carbon content is more than 50%. 4.4.2 Result calculation 9, 10 -- sulfur determination cup. Figure 2 -- Sulfur determination device 4.5.4 Analysis procedures 4.5.4.1 Device tightness inspection: quickly increase the furnace temperature to 1 200 °C ~ 1 250 °C; introduce in oxygen or air; adjust the flow rate to 0.7 L/min ~ 0.8 L/min; check the device for no air leakage before testing. 4.5.4.2 Sample determination: add 2/3 volume of hydrochloric acid solution to the sulfur determination cup; add 10 mL of starch-potassium iodide solution; dropwise add potassium iodate standard solution to make the solution in the sulfur-determination cup to be light blue; use the same method to prepare a reference solution to determine the endpoint. Pass gas for 4 ~ 5 minutes; if the blue color of the solution in the sulfur-determination cup disappears, add the potassium iodate standard solution dropwise until the blue color does not disappear. Accurately weigh 0.2 g ~ 1.0 g of the dried samples (depending on the sulfur content) to the nearest 0.1 mg. Put it into a burned porcelain boat; quickly use a sulfur-free metal hook to push the porcelain boat into the combustion tube; immediately block the nozzle; perform ventilation combustion at 1 200 °C ~ 1 250 °C. The ventilation speed should be 80 ~ 100 bubbles per minute. When the gas enters the lower part of the sulfur-determination cup to make the blue disappear, immediately add the potassium iodate standard solution dropwise; the dropping rate shall be such that the solution in the absorber keeps the original blank light blue as the limit; it’s the end until the solution's light blue remains unchanged for 1 min ~ 2 min. 4.5.4.3 Determination of correction factor: weigh 1 g of sulfur standard sample to the nearest 0.1 mg. In a porcelain boat that has been burned, proceed the followings as 4.5.4.2. 4.5.5 Result calculation 4.5.5.1 The correction factor F is calculated according to Formula (7): Where: F -- correction factor, that is, the mass of sulfur that is equivalent to 1.00 mL of potassium iodate solution, in micrograms per milliliter (μg/mL); m5 -- the mass of sulfur standard sample, in grams (g); 4.6.1.2.4.2 Accurately absorb 10.0 mL of solution A; put it in a 250 mL volumetric flask; use water to dilute to the mark; shake well. This solution contains 0.04 mg of iron per milliliter; this is solution B. 4.6.1.2.4.3 Drawing of working curve Accurately measure 0.0 mL, 1.0 mL, 3.0 mL, 5.0 mL, 7.0 mL, 10.0 mL, 15.0 mL, 20.0 mL of iron standard solution B (equivalent to 0.00 mg, 0.04 mg, 0.12 mg, 0.20 mg, 0.28 mg, 0.40 mg , 0.60 mg, 0.80 mg of iron); respectively put them into 100 mL volumetric flasks; use water to dilute to about 50 mL; add 2 mL of sulfosalicylic acid solution (200 g/L); shake well. Add aqueous ammonia solution dropwise, to change the color of the solution from purple to yellow with an excess of 4 mL; use water to dilute to the mark; shake well. Let stand for 10 min. Select a 1 cm cuvette; use water as a reference; measure the absorbance of the solution at a wavelength of 420 nm. Take the iron content as the abscissa and the absorbance as the ordinate to draw the working curve. 4.6.1.2.5 Sulfosalicylic acid solution (200 g/L). 4.6.1.2.6 Ammonium thiocyanate solution (100 g/L). 4.6.1.3 Instruments 4.6.1.3.1 Balance: the sensitivity is 0.1 mg. 4.6.1.3.2 Oven or other instruments of equivalent performance: the working temperature is 105 °C ~ 110 °C. 4.6.1.3.3 Spectrophotometer or other instruments of equivalent performance. 4.6.1.4 Analysis procedures 4.6.1.4.1 Accurately weigh 0.5 g (if the iron content is less than 0.5%, 1 g ~ 3 g may be taken) of the dried sample to the nearest 0.1 mg. Put in a 150 mL beaker; use a small amount of water to wet the sample; add 25 mL (density of 1.19) of hydrochloric acid; stir, so that the sample is completely immersed in the acid; cover the watch dish; place it on the hot plate; keep it slightly boiling for 20 min; take it down; use water to wash the watch glass and the cup wall; cool slightly, use a medium-speed qualitative filter paper to filter in a 250 mL volumetric flask; use hot water to wash until there is no iron ions (use ammonium thiocyanate solution to check, there is no red); after cooling, dilute to the mark; shake well. This is the sample solution. 4.6.1.4.2 Pipette 10 mL of sample solution into a 100 mL volumetric flask; use water to dilute to about 50 mL; add 2 mL of sulfosalicylic acid solution (200 g/L); shake well. The following steps are the same as 4.6.1.2.4.3. 4.6.1.5 Result calculation heat and boil for 3 ~ 5 minutes. Remove and cool to room temperature; transfer to a 250 mL volumetric flask; use water to dilute to the mark; mix well. 4.6.2.2.9 Ethylene diamine tetraacetic acid (EDTA) standard solution [c (EDTA) = 0.015 mol/L] 4.6.2.2.9.1 Preparation Weigh 5.6 g of EDTA into a 1 000 mL beaker; add 600 mL of water; heat to dissolve; cool; filter; use water to dilute to 1 000 mL. 4.6.2.2.9.2 Calibration Accurately measure 25.00 mL of calcium carbonate standard solution in a 400 mL beaker; use water to dilute to about 200 mL; add an appropriate amount of CMP mixing indicator; add potassium hydroxide solution (200 g/L) dropwise when stirring until green fluorescence appears; add an excess of 1 mL ~ 2 mL; use EDTA standard solution to titrate until the green fluorescence disappears and it shows red. The titer T of the EDTA standard solution to ferric oxide is calculated as follows: Where: T -- the mass of ferric oxide that is equivalent to 1.00 mL of EDTA standard solution, in milligrams (mg); C1 -- the mass of calcium carbonate that is contained in 1.00 mL of calcium carbonate standard solution, in milligrams per milliliter (mg/mL); V1 -- the volume of the divided calcium carbonate standard solution, in milliliters (mL); V2 -- the volume of EDTA standard solution that is consumed during calibration, in milliliters (mL); M1 -- molecular weight of ferric oxide; M2 -- molecular weight of calcium carbonate. 4.6.2.3 Instruments 4.6.2.3.1 Balance: the sensitivity is 0.1 mg and 0.1 g. 4.6.2.3.2 Oven or other instruments of equivalent performance: the working temperature is 105 °C ~ 110 °C. ......

Similar standards: GB/T 3518-2023  GB/T 3519-2023  
Similar PDFs (Auto-delivered in 9 seconds): GB/T 3521-2023  GB/T 3518-2023  GB/T 3074.4-2016  GB/T 24533-2019