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YS/T 575.2-2007: PDF in English (YST 575.2-2007)

YS/T 575.2-2007 NON-FERROUS METAL INDUSTRY STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 71.100.10 Q 52 Replacing YS/T 575.2-2006 Methods for chemical analysis of bauxite - Part 2: Determination of silicon dioxide content - Gravimetric- molybdenum blue photometric method ISSUED ON: NOVEMBER 14, 2007 IMPLEMENTED ON: MAY 01, 2008 Issued by: National Development and Reform Commission Table of Contents Foreword ... 3  1 Scope ... 6  2 Method principle ... 6  3 Reagents ... 6  4 Instruments ... 7  5 Specimen ... 7  6 Analysis steps ... 8  7 Calculation of analysis result ... 9  8 Precision ... 10  9 Quality assurance and control ... 10  - Part 16: Determination of phosphorus pentoxide content - Molybdenum blue spectrophotometric method; - Part 17: Determination of sulfur content - Direct combustion-iodometric method; - Part 18: Determination of total carbon content - Non-aqueous titrimetric method after combustion; - Part 19: Determination of the loss on ignition - Gravimetric method; - Part 20: Preparation of pre-dried sample; - Part 21: Determination of organic carbon content titrimetric method; - Part 22: Determination of hydroscopic moisture in analytical samples - Gravimetric method; - Part 23: Determination of element contents X-ray fluorescence spectrometric method; - Part 24: Determination of carbon content and sulfur content - Infrared absorption method. This Part is Part 2. This Part replaces YS/T 575.2-2006 (formerly GB/T 3257.2-1999). This Part is a modification to YS/T 575.2-2006. Compared with YS/T 575.2- 2006, the main changes in this Part are as follows: - added precision; - unified the drying temperature of the specimen as 110°C±5°C. 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 organization of this Part: China Aluminum Corporation Zhengzhou Research Institute. The drafting organization of this Part: China Aluminum Corporation Shanxi Branch. Main drafters of this Part: Yuan Xiaoke, Wang Yonghui, Zou Xiaowei, He Ruihong. Methods for chemical analysis of bauxite - Part 2: Determination of silicon dioxide content - Gravimetric- molybdenum blue photometric method 1 Scope This Part specifies the determination method of silicon dioxide content in bauxite. This Part is applicable to the determination of silicon dioxide content in bauxite. The determination range is ≥15%. 2 Method principle The specimen is melted and decomposed by sodium hydroxide. After it is leached by hydrochloric acid, it shall be evaporated till salt is precipitated. Add hydrochloric acid and ammonium chloride. Filter and burn into silica. Then use hydrofluoric acid to treat so as to make silicon volatilized and removed as silicon tetrafluoride. The weight difference before and after hydrofluoric acid treatment shall be the amount of silica in the precipitate. Use molybdenum blue photometric method to determine the amount of residual silica in the filtrate. The sum of the two shall be the amount of silica in the specimen. 3 Reagents 3.1 Sodium hydroxide. 3.2 Ammonium chloride. 3.3 Ammonia. 3.4 Hydrochloric acid (1+1). 3.5 Hydrochloric acid (1mol/mL). 3.6 Hydrochloric acid (5+95). 3.7 Hydrofluoric acid (ρ1.13g/mL). 3.8 Sulfuric acid (1+1). 6 Analysis steps 6.1 Test portion Weigh 0.5g of specimen (5), to the nearest of 0.0001g. 6.2 Determination times It shall independently conduct two determinations to a same specimen. Take the average value. 6.3 Blank test Conduct blank test with test portion. 6.4 Determination 6.4.1 Put the test portion (6.1) into a 30mL silver crucible. Add 3g of sodium hydroxide (3.1) to cover. Cover the crucible. Place in a 750°C±10°C muffle furnace. Melt 20min (5min for blank melting). Take it out. Rotate the crucible to make the melt adhere to the inner wall of the crucible evenly. Cool. 6.4.2 Use a filter paper to clean the outer wall of the crucible. Put the crucible upright in a 300mL beaker. Carefully add 20mL of near-boiling water. Immediately cover the watch glass to prevent splash. After the violent reaction stops, use hydrochloric acid (3.4) and water to clean the crucible. Add 20mLof hydrochloric acid (3.9). Stir evenly. Place on a low-temperature heating plate to evaporate to dry (the salt shall be loose). Add 1g of ammonium chloride (3.2) and 15mL of hydrochloric acid (3.9). Use a glass rod to stir to make all salts on the cup wall dissolved in acid. Cover the watch glass. Under a near-boiling state, insulate for 20min. Use hot hydrochloric acid (3.6) to wash the watch glass and the beaker wall till the volume is about 50mL. Immediately stir till the salt is completely dissolved. Use a fast-quantitative filter paper to filter. Use a 250mL volumetric flask to undertake the filtrate. Use hot hydrochloric acid (3.6) to wash first and precipitate to iron-free ions [use potassium thiocyanate solution (3.10) to check]. Continue using warm water to wash till chloride-free ion [use silver nitrate solution (3.11) to check]. 6.4.3 Place the precipitation together with the filter paper in the platinum crucible. Dry carefully. After ashing, put it into a high-temperature furnace. Burn at 980°C for 1h. Take it out. Place on a dryer. Cool to room temperature. Weigh. Repeat burning till the constant weight (m1). Along with the inner wall of the crucible, add 3~5 drops of water to moisture the precipitation. Add 4 drops of sulfuric acid (3.8) and 5mL of hydrofluoric acid (3.7). Evaporate at low temperature till it has white smoke. Remove it to cool for a while. Then add 5mL of hydrofluoric acid (3.7). Continue heating till all white smokes are out. Put the ......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.