GB/T 3884.2-2000 Chemical analysis methods for copper concentrates - Determination of gold and silver content
Some standard content:
GB/T3884.2—2000
This standard adopts two chemical analysis methods to determine the gold and silver content in copper concentrate. Determination of silver by atomic absorption spectrophotometry
Method 1 of this standard is a revision of GB/T3884.15—1986 "Chemical analysis method for copper concentrate", and its determination range is adjusted from 10.0~50.0g/t to 10.0~300.0g/t. Method 2 of this standard is a non-equivalent adoption of ISO10378:1994 "Determination of gold and silver content in copper sulfide concentrate", which is a revision of GB/T3884.2-1983 "Chemical analysis method for steel concentrate - determination of gold and silver content by dry and wet assay" and GB/T3884.14—1986 "Chemical analysis method for copper concentrate - determination of gold and silver content by fire assay". The explanation of non-equivalence is as follows: a) The determination range of this method is: Au, 0.50~40.00g/t, Ag, 50.0~2500.0g/t. The determination range of IS010378:1994 is Au0.50~3000.00g/t, Ag.25.01500.0g/t. b) The analytical technology is exactly the same.
This standard complies with:
GB/T1.1—1993 Guidelines for standardization work Unit 1: Rules for drafting and expressing standards Part 1: Basic provisions for standard writing
GB/T1.4—1988 Guidelines for standardization work Provisions for the writing of chemical analysis methods GB/T1467—1978 General principles and general provisions for chemical analysis methods for metallurgical products GB/T7728—1987 General principles for flame atomic absorption spectrometry for chemical analysis of metallurgical products GB/T17433—1998 Basic terms for chemical analysis of metallurgical products This standard replaces GB/T3884.2—1983, GB/T3884.14-1986, and GB/T3884.15—1986 from the date of implementation. Appendix A in this standard is a reminder appendix. This standard is proposed by the State Bureau of Nonferrous Metals Industry. This standard is under the jurisdiction of the China Nonferrous Metals Industry Standard Metrology and Quality Research Institute. This standard was drafted by Daye Nonferrous Metals Company. The main drafters of this standard, Method 1: Shuai Gongqi, Xiao Zehong, Ma Chenwu, Method 2: Wang Yongbin, Shuai Gongqi, Peng Demin. 8
1 Scope
National Standard of the People's Republic of China
Chemical analysis methods of copper concentrates
Determination of gold and silver content
Methods for chemical analysis of copper concentratesDetermination of gold and silver contentMethod 1 Determination of silver content by flame atomic absorption spectrometryThis standard specifies the method for determining the silver content in copper concentrates. This standard is applicable to the determination of silver content in copper concentrates. Determination range: 10.0～300.0g/t. 2 Method Summary
GB/T3884.2-2000
Replaces GB/T3884.2-1983
GB/T3884.14—1986
GB/T3884.15—1986
The sample is dissolved in nitric acid and pernitrogen acid (if the silicon content is high, add a little ammonium bifluoride). In dilute hydrochloric acid medium, use an atomic absorption spectrometer at a wavelength of 328.1nm and an air-acetylene flame to measure the absorbance of silver. After deducting the background absorption, calculate the amount of silver according to the standard curve. 3 Reagents
3.1 Ammonium bifluoride.
3.2 Hydrochloric acid (p1.19g/mL).
3.3 Nitric acid (p1.42g/mL), high-grade purity. 3.4 Perfluoric acid (p1.67g/mL).
3.5 Silver standard stock solution: Weigh 0.1000g of metallic silver (99.95%) into a 200mL beaker, add 20mL of nitric acid (1+1), heat until completely dissolved, cool to room temperature, transfer to a 200mL brown container bottle, dilute to scale with chloride-free ion exchange water, and mix well. This solution contains 500μg of silver in 1mL.
3.6 Silver standard solution: Transfer 20.00mL of silver standard stock solution into a 100mL volumetric flask, dilute to scale with nitric acid (1+99), and mix well. This solution contains 100μg of silver in 1mL.
4 Instruments
Atomic absorption spectrometer with a silver hollow cathode lamp. Under the best working conditions of the instrument, any instrument that can meet the following indicators can be used. Characteristic concentration: In a solution consistent with the matrix of the measured sample solution, the characteristic concentration of silver should not exceed 0.018μg/mL. Precision: When the absorbance is measured 10 times with the highest concentration standard, its standard deviation should not exceed 1.0% of the average absorbance; when the absorbance is measured 10 times with the lowest concentration standard solution (not the "zero" standard solution), its standard deviation should not exceed 0.5% of the average absorbance of the highest concentration standard solution.
Linearity of working curve: Divide the working curve into five sections according to concentration, and the ratio of the absorbance difference of the highest section to the absorbance difference of the lowest section shall not be less than 0.85.
Approved by the State Administration of Quality and Technical Supervision on February 16, 2000, implemented on August 1, 2000
GB/T3884.2—2000
See Appendix A (Suggested Appendix) for instrument working conditions 5 Samples
5.1 The sample size should not be greater than 0.082mm. 5.2 The sample should be dried at 100-105℃ for 1h and then placed in a desiccator to cool to room temperature. 6 Analysis steps
6.1 Test sample
Weigh the test sample according to Table 1, accurate to 0.0001g. Table 1
Silver content·g/t
10.0~40.0
>40.0~100.0
>100.0~300.0
Test sample amount, g
Carry out two tests independently and take the average value. 6.2 Blank test
Carry out a blank test along with the test sample.
6.3 Determination
Determination of volume, mL
Add hydrochloric acid, mL
6.3.1 Place the sample (6.1) in a 250mL beaker, add a small amount of water to moisten it, add 15mL nitric acid (add a small amount of ammonium bifluoride when containing silicon monoxide), cover with a glass, heat to dissolve and shake from time to time, dissolve to a small volume, add 5mL perchloric acid and continue to heat until it smokes, move to a low temperature place and continue to dissolve until there is no black residue at the bottom of the cup, remove and cool slightly, add 5mL hydrochloric acid, continue to heat until the perchloric acid emits white smoke, evaporate to wet salt, remove and cool. 6.3.2 Add hydrochloric acid according to Table 1, blow water on the table and the wall of the cup, heat to dissolve the salts, remove and cool to room temperature. 6.3.3 Transfer the solution (6.3.2) into a volumetric flask, dilute to the scale with water, mix well, and let it stand (or dry filter). 6.3.4 Using air acetylene flame, adjust the zero value with the blank test solution accompanying the sample on the atomic absorption spectrometer according to the wavelength in Table A1 of Appendix A, measure the absorbance of the test solution, deduct the background absorption, and find the corresponding silver concentration from the working curve. 6.4 Drawing of working curve
6.4.1 Transfer 0.0.20, 0.40, 0.600.80, 1.00mL of silver standard bath solution, cover them in a set of 100mL volumetric flasks respectively, add 20.0mL of hydrochloric acid, dilute to the scale with water, and mix well. 6.4.2 Under the same conditions as measuring the sample solution, adjust the zero value with the "zero" concentration solution, measure the absorbance of the silver standard solution at the wavelength in Table A1 of Appendix A, and draw the working curve with the silver concentration as the horizontal axis and the corresponding absorbance as the vertical axis. 7
Analysis result statement
Calculate the silver content according to formula (1):
Ag(g/t)=$
Wherein: c—silver concentration found from the working curve, μg/mL: V-
-volume of the sample solution, mL
mo-—mass of the sample, g.
The result is expressed to one decimal place.
8 Allowable difference
GB/T3884.2-—2000
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2
Silver content
>20.0~50.0
>50.0~100.0
>100.0~300.0
Method 2 Determination of gold and silver content by fire assay
9 Range
This standard specifies the method for determining the gold and silver content in copper concentrate. Allowable tolerance
This standard is applicable to the determination of gold and silver content in copper concentrate. Determination range: Au0.50~40.00g/t, Ag: 50.0~2 500.0g/t.
10 Method Summary
The sample is prepared and melted at high temperature. The molten metal lead captures the precious metals in the sample to form lead buckles. Other substances in the sample and the flux form fusible slag. The lead buckle ash is blown to obtain gold and silver mixed particles. The impurities adhering to the surface of the mixed particles are removed. The gold is separated by nitric acid. The silver content is determined by titration and the gold content is determined by weight.
11 Reagents
Sodium carbonate: industrial pure, powder.
Lead oxide: industrial pure, powder (gold content <0.5g/t, silver <5g/t) Silicon dioxide: industrial pure, powder.
Borax: powder. Www.bzxZ.net
Starch: powder.
Potassium nitrate, powder.
Sodium chloride: industrial pure, powder.
Pure silver: 99.99%.
Lead foil: thickness 0.1~0.15mm, weight 35g, square, no gold or silver. Nitric acid (pl.42g/mL), high purity.
Nitric acid (1+7), no chloride.
Nitric acid (1+1), no chloride.
Ammonium ferric sulfate indicator: take one part of saturated ammonium ferric sulfate solution, add three parts of nitric acid (1+3), mix well. 11.14
Potassium thiocyanate standard titration solution
Weigh 0.5g potassium thiocyanate, put it in a 100mL beaker, add water to dissolve, transfer to a 1000mL volumetric flask, dilute to the scale, mix well. Let it stand for one week, filter and set aside.
11.14.2 Calibration
Weigh three portions of 10.00~15.00 mg of pure silver and place them in 50 mL porcelain pots respectively. Add 10~15 mL of nitric acid (11.12), dissolve with slight heat and evaporate to about 1~2 mL. Add a small amount of water and 0.5 mL of ammonium ferric sulfate indicator, and titrate with potassium thiocyanate standard titration solution until light red is the end point.
Calculate the actual concentration of potassium thiocyanate standard titration solution according to formula (2). m
Where: c-
-actual concentration of potassium thiocyanate standard titration solution, mol/L-weight of silver weighed, mg;
VI-volume of potassium thiocyanate standard titration solution consumed in titrating silver during calibration, mLM-
-mole weight of silver, g/mol.
When the range of the three calibration results is not greater than 4X10~5mol/L, take the average of the three calibration results, otherwise recalibrate. 12 Instruments and Equipment
12.1 Balance.
12.1.1 Blood balance: sensitivity 1g.
12.1.2 Analytical balance: sensitivity 0.001g. 12.1.3 Microbalance: sensitivity 0.01mg. 12.1.4 Ultramicrobalance: sensitivity 0.001mg. 12.2 Assay furnace: Maximum heating temperature 1350℃. (2)
12.3 Clay pot: Made of refractory clay, with an exterior height of 130mm, top outer diameter of 90mm, bottom outer diameter of 50mm, and a volume of about 300mm.
12.4 Oven.
12.5 Ash machine.
12.6 Sample crusher.
12.7 Ash mill: Top inner diameter 35mm, bottom outer diameter 40mm, height 30mm, depth about 17mm. Preparation method: Mix 1 part of bone ash with 3 parts of cement (No. 425). Add appropriate amount of water and stir, press into shape on the ash machine, and keep for use after three months.
12.8 Porcelain crucible (low type): Volume 30mL12.9 Porcelain: Volume 50mL.
12.70 Cast iron mold.
12.11 Medical hemostatic forceps.
13 Test sample
13.1 The sample particle size should not be greater than 0.082mm. 13.2 The sample should be dried at 100-105℃ for 1h and then placed in a desiccator and cooled to room temperature. 14 Analysis steps
14.1 Test sample
According to the content of copper, gold, silver and sulfur in the test sample, weigh 15-25g of sample for each portion, accurate to 0.001g. Perform (at least) two independent determinations and take the average value. 14.2 Blank test
14.2.1 Perform a blank test with the sample (three parallel determinations and take the average value). 14.2.2 Test method
Weigh 25g sodium carbonate, 200g lead oxide, 15g silicon dioxide, 7g ketone sand, 4g starch, double cover with sodium nitride about 10mm thick, and the following 12
perform according to 14.3.2 to 14.3.4.
14.3 Determination
14.3.1 Mixing
GB/T3884.2-2000
Based on the chemical composition and sample amount of the sample, mix and stir in clay scale according to the following principles, and cover with sodium chloride about 10mm thick.
Sodium carbonate: 1.5 times the sample amount.
Lead oxide: 30 times the copper amount or 25 times the sulfur amount plus the lead deduction amount (if the content of iron, arsenic, antimony, bismuth, nickel, etc. is high, increase its amount appropriately). Silicon dioxide: The amount to be added is calculated based on the slag type with a silica acidity of 0.5. Potassium nitrate and starch: Add appropriately according to the sulfur and carbon content in the test sample. 14.3.2 Melting
Put the prepared materials in a 900℃ assay furnace, heat up to 1100℃ for 30 minutes, keep warm for 15 minutes, pour the molten material into a preheated cast iron mold, and keep it for re-melting. After cooling, the lead buckle is separated from the slag, and the slag is kept for re-processing. Hammer the lead buckle into a cube. A suitable lead buckle should have a bright surface and weigh 30 to 45g, otherwise the ingredients should be readjusted and melted. Remove the covering agent from the slag and return it to the original crucible.
14.3.3 Ash Blowing
Put the lead button into the ash that has been preheated in the 900℃ gold assay furnace for 30 minutes, close the furnace door for 1-2 minutes, wait until the black film on the lead liquid surface is removed, open the furnace door slightly to reduce the furnace temperature to 840℃ as soon as possible for ash blowing, and the ash blowing is finished when the combined particles begin to flash. Move the ash III to the furnace door, put it into the ash blood tray after it cools slightly, and keep the ash blood residue for disposal. 14.3.4 Gold Separation
Take out the gold and silver combined particles with medical hemostatic forceps, brush off the adhering impurities, hammer into thin slices, place in 30mL porcelain culture glass, add 10mL hot nitric acid (11.1I), keep it on a low-temperature electric heating plate, evaporate to about 2mL, take it off and cool it slightly, then add 10mL hot nitric acid (11.12), evaporate to about 2mL, take it off and cool it. Wash the Kunwa wall with hot water, transfer the solution into 50mL porcelain by pouring method, and wash the crucible wall twice with hot water. After cooling, add about 0.5mL of ammonium ferric sulfate indicator, and titrate with potassium thiocyanate standard titration solution until light red is the end point. Place the porcelain crucible containing gold particles on a high-temperature electric furnace and burn for 5 minutes, remove and cool, and weigh. Note: When the ratio of silver to gold in the composite particles is less than 3:1, pure silver should be added to the composite particles. The method is: weigh 3 times the amount of silver in the composite particles, and wrap the composite particles and pure silver with lead foil. The following is carried out according to 14.3.3~14.3.4. 14.3.5 Correction (residue reprocessing)
Put the slag and ash stored in the ground into a grinder, crush them, add 50g sodium carbonate, 15g silicon dioxide, 20g borax, and 4g starch, stir, and cover with 10mm thick sodium chloride. The following is carried out according to 14.3.214.3.4. 15 Expression of analysis results
According to formula (3) and formula (4), the gold and silver contents were calculated respectively: ms+ms-m×10
Au(g/t)=
Ag(g/t) = c(V.+V.=V) × 0. 107 87 × 10mo
Wherein: m2—the mass of gold obtained after the first gold-silver mixed particles were separated, mg; m3—the mass of gold recovered by residue reprocessing, mg; m—the mass of gold in the blank mixed particles of the first gold test, mgc—the concentration of potassium thiocyanate standard titration solution, mol/L; V2—the volume of potassium thiocyanate standard titration solution consumed after the first silver titration, mL; V—the volume of potassium thiocyanate standard titration solution consumed after residue reprocessing, mLV—the volume of potassium thiocyanate standard titration solution consumed by the silver recovered by the blank mixed particles of the first gold test and the blank residue, mL: + (3)
m. The mass of the sample + g
GB/T 3884.2-2000
0.10787—the mass equivalent to 1.00mL potassium thiocyanate standard titration solution Lc(KSCN)=1.00mol/L, g/mol. The results obtained, the gold content is expressed to two decimal places; the silver content is expressed to one decimal place. Allowable difference
The difference between the analysis results of laboratories shall not be greater than the allowable difference listed in Table 3. Table 3
Gold content
0.50~1.20
>1.20~2.00
>2.00~3.00
>3.00~4.00
>4.00~5.00
>5. 00~7. 00
>7.00~10.00
>10.00~15,00
>15.00~20.00
>20.0 0~30.00
>30.00~40.00
Allowance difference
Silver content
50.0~100.0
> 100.0~500.0
>500.0~1000.0
Allowance
GB/T3884.2-2000
Appendix A
(Suggestive Appendix)| |tt||Instrument working conditions
The working conditions for measuring the amount of silver using a PE-1100B atomic absorption spectrometer are shown in Table A1. Table AI
Wavelength, nm
Lamp current, mA| |tt||Spectral passband, nm
Observation height, mm
Air flow, L/min
Acetylene flow, L/min
328.1(332.3 for background Correction
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