YS/T 555.1-2009 English PDF
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YS/T 555.1-2009: Methods for chemical analysis of molybdenum concentrate. Determination of molybdenum content. Lead molybdenum gravimetry
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YS NONFERROUS METALS INDUSTRY STANDARD ICS 77.120.99 H 14 Replacing YS/T 555.1-2006 Methods for chemical analysis of molybdenum concentrate. Determination of molybdenum content. Lead molybdenum gravimetry Issued on: DECEMBER 04, 2009 Implemented on: JUNE 01, 2010 Issued by. Ministry of Industry and Information Technology of the People's Republic of China.
Table of Contents
Foreword... 3 1 Scope... 5 2 Method summary... 5 3 Reagents... 5 4 Instruments... 7 5 Specimen... 7 6 Analysis steps... 7 7 Calculation of analysis results... 9 8 Precision... 10 9 Quality assurance and control... 11Foreword
YS/T 555 "Methods for chemical analysis of molybdenum concentrate" comprises 11 parts. YS/T 555.1, Methods for chemical analysis of molybdenum concentrate. Determination of molybdenum content. Lead molybdenum gravimetry; YS/T 555.2, Methods for chemical analysis of molybdenum concentrate. Determination of silicon dioxide content. Silicon molybdenum blue spectrophotometry and gravimetry; YS/T 555.3, Methods for chemical analysis of molybdenum concentrate. Determination of arsenic content. Atomic fluorescence spectrometry; YS/T 555.4, Methods for chemical analysis of molybdenum concentrate. Determination of tin content. Atomic fluorescence spectrometry; YS/T 555.5, Methods for chemical analysis of molybdenum concentrate. Determination of phosphorus content. Phosphorus molybdenum blue spectrophotometry; YS/T 555.6, Methods for chemical analysis of molybdenum concentrate. Determination of copper, lead, bismuth and zinc content. Flame atomic absorption spectrometry; YS/T 555.7, Methods for chemical analysis of molybdenum concentrate. Determination of calcium oxide content. Flame atomic absorption spectrometry; YS/T 555.8, Methods for chemical analysis of molybdenum concentrate. Determination of tungsten content. Thiocyanate spectrophotometry; YS/T 555.9, Methods for chemical analysis of molybdenum concentrate. Determination of potassium and sodium content. Flame atomic absorption spectrometry; YS/T 555.10, Methods for chemical analysis of molybdenum concentrate. Determination of potassium and sodium content; YS/T 555.11, Methods for chemical analysis of molybdenum concentrate. Determination of oil and moisture content. Gravimetry. This is Part 1. This Part replaces YS/T 555.1-2006 "Molybdenum concentrates. Determination of molybdenum content" (formerly GB/T 15079.1-1994). Compared with YS/T 555.1-2006, the main changes in this Part are as follows. - Before adding ammonia to precipitate iron and other impurities, add a small amount of filter paper pulp to the solution; - The addition rate of lead acetate solution is specified as 1 mL/3 s; - Precision clauses have been added; - The text format has been modified, and quality assurance and control clauses have been added. This Part was proposed by and shall be under the jurisdiction of National Technical Committee on Non-ferrous Metals of Standardization Administration of China. Main drafting organizations of this Part. Jinduicheng Molybdenum Group Co., Ltd., and China Nonferrous Metals Industry Standards, Metrology and Quality Research Institute. The drafting organizations of this Part. Luoyang Luanchuan Molybdenum Group Co., Ltd., and Jiangxi Copper Corporation (Dexing) Mining New Technology Development Co., Ltd. Main drafters of this Part. Wang Zhongqi, Zhang Jiangfeng, Zhang Xiaopu, Zhang Min, Tian Wenhui, Ma Yongxiang. Main verifiers of this Part. Tian Yonghong, Shu Binqiang, and Li Hongjun. Versions of standard substituted by this Part are. - GB/T 15079.1-1994; - YS/T 555.1-2006. Methods for chemical analysis of molybdenum concentrate. Determination of molybdenum content. Lead molybdenum gravimetry1 Scope
This Part specifies the method for determining the molybdenum content in molybdenum concentrate. This Part applies to the determination of molybdenum content in molybdenum concentrate. Determination range. ≥40%. This Part does not apply to the determination of molybdenum content in molybdenum concentrate with a tungsten content greater than 2%.2 Method summary
The specimen is decomposed in a saturated nitric acid-potassium chlorate solution. Impurities are precipitated with ammonia. It is then filtered. The filtrate is placed in an acetic acid-ammonium acetate buffer medium, where lead acetate precipitated the molybdate ions in the solution to form lead molybdate. The precipitate is filtered, ignited, and weighed to constant weight. Molybdenum in the residue after ammonia separation is determined and corrected using a thiocyanate spectrophotometric method.3 Reagents
Unless otherwise specified, only reagents confirmed to be analytically pure and distilled or deionized water or water of equivalent purity shall be used in the analysis. 3.1 Mixed flux. weigh 500 g of anhydrous sodium carbonate and 250 g of zinc oxide. Mix well and grind finely. Store in a ground glass bottle. 3.2 Ammonium nitrate. 3.3 Hydrochloric acid (ρ 1.19 g/mL). 3.4 Nitric acid (ρ 1.42 g/mL). 3.5 Ammonia solution (ρ 0.90 g/mL). 3.6 Saturated potassium nitrate-chlorate solution. 3.7 Hydrochloric acid (1+1). 3.8 Hydrochloric acid solution (1+19). 3.9 Sulfuric acid (1+1). 3.10 Ammonia solution (1+1). 3.11 Ammonia solution (3+97). 3.12 Sodium hydroxide solution (200 g/L). 3.13 Acetic acid-ammonium acetate buffer solution. weigh 250 g of ammonium acetate into a 1000 mL beaker. Dissolve in 500 mL of water, then add 150 mL of acetic acid. Filter and dilute with water to 1000 mL. Mix well. 3.14 Ferric chloride solution (48 g/L). weigh 48 g of ferric chloride (FeCl3·6H2O) and dissolve it in 50 mL of hydrochloric acid (3.3). Dilute with water to 1000 mL. Mix well. 3.15 Ammonium nitrate solution (30 g/L). weigh 30 g of ammonium nitrate and dissolve it in 1000 mL of water. Adjust the pH to 8~9 with ammonia water (3.10). 3.16 Ammonium acetate solution. measure 25 mL of acetate-ammonium acetate buffer solution (3.13). Dilute with water to 500 mL. Mix well. 3.17 Lead acetate solution (18 g/L). weigh 18 g of lead acetate into a 1000 mL beaker. Add 15 mL of glacial acetic acid and 80 mL of water to dissolve. Filter and dilute with water to 1000 mL. 3.18 Potassium thiocyanate solution (300 g/L). 3.19 Thiourea solution (50 g/L). 3.20 Sulfuric acid-copper sulfate solution. weigh 1 g of copper sulfate (CuSO4·5H2O) into a 1000 mL beaker. Add 1000 mL of sulfuric acid (3.9) to dissolve. Mix well. 3.21 To make the filter paper pulp, tear quantitative filter paper into pieces. Place it in a 500 mL beaker. Add water, and boil it into a paste. 3.22 Molybdenum standard stock solution (100 μg/mL). weigh 0.1500 g of molybdenum trioxide (primary standard reagent) into a 300 mL beaker. Add 2 mL of sodium hydroxide solution (3.12) and 100 mL of water. Heat to dissolve. Cool. Transfer to a 1000 mL volumetric flask. Dilute to the mark with water. Mix well. This solution contains 100 μg of molybdenum per mL. 3.23 Molybdenum standard solution. transfer 10.00 mL of molybdenum standard stock solution (3.22) into a 100 mL volumetric flask. Dilute to the mark with water. Mix well. This solution contains 10 μg of molybdenum per mL. 3.24 Methyl orange solution (1 g/L). 3.25 Tannin solution (10 g/L, used as an external indicator). 3.26 Phenolphthalein solution (1 g/L). prepared with ethanol (1+1).4 Instruments
Spectrophotometer.5 Specimen
The specimen should be pre-treated to remove oil and moisture. Its particle size should be less than 0.090 mm. The specimen should be dried at 100℃~105℃ for 1 h, then cooled to room temperature in a desiccator.6 Analysis steps
6.1 Test material Weigh approximately 0.20 g of the specimen, accurate to 0.0001 g. Perform two independent determinations and take the average value. 6.2 Blank test Conduct a blank test along with the test material. 6.3 Determination 6.3.1 Determination of molybdenum in specimens with tungsten content less than 0.25% 6.3.1.1 Place the test material (6.1) in a 400 mL beaker. Add 20 mL of saturated potassium nitric acid-chlorate solution (3.6). Cover with a watch glass. Dissolve by heating at low temperature. Evaporate to 3 mL~5 mL. Add another 5 mL of saturated potassium nitric acid-chlorate solution (3.6). Continue evaporating to 3 mL. Remove and let cool slightly. Add 10 mL of hydrochloric acid (3.3). Continue heating and evaporating to 3 mL~4 mL. Remove. 6.3.1.2 Add 10 mL of hydrochloric acid (3.3) to the test solution. Rinse the glass and beaker walls with water. Dilute to approximately 80 mL. Boil. Add a small amount of paper pulp. Remove and let cool slightly. Slowly add ammonia (3.5) while stirring. Allow the hydroxide to precipitate, then add an excess of 20 mL. Boil for 5 min. Remove and filter while hot using rapid filter paper. Wash the precipitate 4~5 times with hot ammonia solution (3.11). Add 10 mL of hydrochloric acid (3.7) to dissolve the precipitate in the original beaker. Rinse the filter paper with hot water until no yellow color remains. Dilute the filtrate to 50 mL with water. Add 25 mL of ammonia (3.5). Boil for 5~6 min. Filter the precipitate into the first filtrate using the original filter paper, then wash the precipitate 4~5 times with hot ammonia solution (3.11). Retain the residue for the correction determination of molybdenum. 6.3.1.3 Dilute the filtrate with water to approximately 300 mL. Add 2 drops of methyl orange solution (3.24). Neutralize with hydrochloric acid (3.7) until the solution turns orange-red. Add an excess of 10~12 drops. Add 50 mL of acetate-ammonium acetate buffer solution (3.13). Heat to a gentle boil. Remove from heat. Add lead acetate solution (3.17) with stirring using a burette. Add lead acetate evenly at 1 mL/3 s until the tannin external indicator solution (3.25) no longer turns yellow. Add an excess of 2~3 mL. Add a small amount of filter paper pulp (3.21). Heat to a gentle boil, then let stand at room temperature for 30 min. Remove from heat. Filter with medium-speed quantitative filter paper. Wipe away any precipitate adhering to the beaker and glass rod with a small piece of filter paper. Wash the precipitate 10~12 times with hot ammonium acetate solution. Transfer the precipitate and filter paper to a pre-weighed porcelain crucible. Dry. Ash. Heat in a furnace at 550℃~600℃ until constant weight (weigh after cooling in a desiccator). 6.3.2 Determination of molybdenum in specimens with a tungsten content of 0.25%~2% 6.3.2.1 Place the test material (6.1) in a 300 mL beaker. Add 20 mL of nitric acid (3.4). Cover with a watch glass. Heat to dissolve. Evaporate to a volume of 3 mL~5 mL. Remove and let cool slightly. Add 10 mL of hydrochloric acid (3.3) and continue heating to a volume of 3 mL~4 mL. Remove from heat. 6.3.2.2 Add 10 mL of hydrochloric acid (3.3) and 50 mL of water to the test solution. Boil. Filter while hot using rapid filter paper. Wash the precipitate 7~8 times with hydrochloric acid solution (3.8), and the beaker 2~3 times. Transfer the residue adhering to the beaker into the filtrate using ammonia water (3.10). Wash with water. Retain the filter paper and residue. Add 6 mL of ferric chloride solution (3.14) and 2~3 g of ammonium nitrate (3.2) to the filtrate. Boil. Let cool slightly. Slowly add ammonia water (3.5) while stirring, allowing the hydroxide to precipitate, then add an excess of 10 mL. Boil until a slight ammonia odor is detected. Remove from heat. Adjust the pH of the solution to 8~9 using hydrochloric acid (3.7) or ammonia (3.10). Filter using fast filter paper. Wash 4~5 times with hot ammonium nitrate solution (3.15). 6.3.2.3 Add 10 mL of hydrochloric acid (3.7) to dissolve the precipitate in the original beaker. Rinse the filter paper with hot water until no yellow color remains. Dilute the filtrate with water to 50 mL. Add 15 mL of ammonia (3.5). Boil until a slight ammonia odor is detected. Adjust the pH of the solution to 8~9 with hydrochloric acid (3.7) or ammonia (3.10). Filter the solution into the filtrate using the original filter paper. Wash 4~5 times with hot ammonium nitrate solution (3.15). Combine the precipitate and residue for the correction determination of molybdenum. 6.3.2.4 Dilute the filtrate with water to approximately 300 mL. The following procedures shall be performed according to 6.3.1.3. 6.3.3 Molybdenum correction 6.3.3.1 Place the residue and filter paper obtained in 6.3.1.3 or 6.3.2.2 into a 30 mL porcelain crucible. Carefully ash. Add 2 g~3 g of mixed flux (3.1). Stir well. Cover the surface with another 1 g~2 g of mixed flux (3.1). Sinter in a high-temperature furnace at 700°C~750°C for 30 min~40 min. Remove and cool. Carefully transfer the crucible and sintered block into a 300 mL beaker. Wash the crucible with 30 mL~40 mL of hot water and remove. Heat to boiling to dissolve the soluble salts. Remove. After cooling, transfer to a 100 mL volumetric flask. Dilute to the mark with water. Mix well. Filter dry. 6.3.3.2 Transfer 20.00 mL of the filtrate (6.3.3.1) to a 50 mL volumetric flask. Add 1 drop of phenolphthalein solution (3.26). Neutralize with sulfuric acid (3.9) until the solution is colorless. Add 8 mL of sulfuric acid-copper sulfate solution (3.20) and 5 mL of thiourea solution (3.19) and mix well. Let stand for 5 min. Add 5 mL of potassium thiocyanate solution (3.18). Dilute to the mark with water. Mix well. Let stand for 30 min. 6.3.3.3 Transfer a portion of the solution into a 3 cm cuvette. Use the blank test solution as a reference. Measure the absorbance at 460 nm using a spectrophotometer. Determine the corresponding mass of molybdenum from the working curve. 6.3.3.4 Drawing the working curve Transfer 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, and 10.00 mL of molybdenum standard solution (3.23) into a set of 50 mL volumetric flasks. Add water to a final volume of 20 mL. Perform the following operations as per 6.3.3.2.Transfer a portion of the solution into a 3 cm cuvette. Measure the absorbance using a reagent blank as a reference. Plot a working curve with the mass of molybdenum on the x-axis and absorbance on the y-axis.7 Calculation of analysis results
Calculate the mass fraction of molybdenum according to formula (1). The value is expressed as a percentage. Where, m1 - Mass of lead molybdate after ignition, in grams (g); m2 - Amount of molybdenum obtained from the working curve, in grams (g); V1 - Total volume of the corrective solution, in milliliters (mL); V2 - Volume of the corrective solution taken, in milliliters (mL); m0 - Mass of the test material, in grams (g); 0.2613 - Conversion factor from lead molybdate to molybdenum. The calculation result is expressed to two decimal places.8 Precision
8.1 Repeatability For two independent determination results obtained under repeatability conditions, the absolute difference between the two determination results should not exceed the repeatability limit (r) within the range of the average values given below, and the occurrence of differences exceeding the repeatability limit (r) should not exceed 5%. The repeatability limit (r) is obtained by linear interpolation using the following data. Molybdenum mass fraction / %. 40.00 50.00 57.00 Repeatability limit (r) / %. 0.30 0.35 0.40 NOTE. The repeatability limit (r) is 2.8Sr, where Sr is the repeatability standard deviation. 8.2 Allowable difference The difference between laboratory analytical results should not exceed the allowable difference listed in Table 1. Table 1 Molybdenum mass fraction / % Allowable difference / %9 Quality assurance and control
Use national or industry-level standard samples (or control standard samples if neither is available). Verify the validity of this analytical method weekly or bi-weekly. If the process goes out of control, identify the cause. Correct the error and re-verify. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
