YS/T 575.2-2007 English PDF (YST575.2-2007)

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YS/T 575.2-2007: Methods for chemical analysis of bauxite. Part 2: Determination of silicon dioxide content. Gravimetric-molybdenum blue photometric method
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