Methods for chemical analysis of limestone and dolomite - Part 1: The determination of calcium oxide and magnesium oxide content - The complexometric titration method and the flame atomic absorption spectrometric method
Foreword
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 3286 consists of the following nine parts under the general title Methods for chemical analysis of limestone and dolomite:
——Part 1: The determination of calcium oxide and magnesium oxide content - The complexometric titration method and the flame atomic absorption spectrometric method;
——Part 2: The determination of silicon dioxide content - The silicomolybdic blue spectrophotometric method and the perchloric acid dehydration gravimetric method;
——Part 3: The determination of aluminium oxide content - The chrome azurol S spectrophotometric method and the complexometric titration method;
——Part 4: The determination of iron oxide content - The o-phenanthroline spectrophotometric method and the flame atomic absorption spectrometric method;
——Part 5: The determination of manganese oxide content;
——Part 6: The determination of phosphorus content;
——Part 7: The determination of sulphur content;
——Part 8: The determination of loss on ignition;
——Part 9: The determination of carbon dioxide content.
This is Part 1 of GB/T 3286.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 3286.1-1998 Methods for chemical analysis of limestone and dolomite - The determination of calcium oxide and magnesium oxide content.
The following main changes have been made with respect to GB/T 3286.1-1998:
——the standard name has been changed to Methods for chemical analysis of limestone and dolomite - Part 1: The determination of calcium oxide and magnesium oxide content - The complexometric titration method and the flame atomic absorption spectrometric method;
——the year numbers of normative references have been canceled, and some reference standards have been added;
——the inter-laboratory collaborative test for precision has been carried out, and the "allowable deviation" has been replaced by the statistical repeatability limit r and reproducibility limit R;
——some text expressions have been changed;
——the technical conditions such as dilution ratio of specimen and strontium chloride dosage have been modified.
This part was proposed by China Iron and Steel Association.
This part is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this part are as follows:
——GB/T 3286.1-1982, GB/T 3286.1-1998;
——GB/T 3286.11-1993.
Methods for chemical analysis of limestone and dolomite - Part 1: The determination of calcium oxide and magnesium oxide content - The complexometric titration method and the flame atomic absorption spectrometric method
WARNING: Persons using this part shall be familiar with normal laboratory practice. This part does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health measures and to ensure compliance with any national regulatory conditions.
1 Scope
This part of GB/T 3286 specifies the determination of calcium oxide content and magnesium oxide content by complexometric titration method and the determination of magnesium oxide content by atomic absorption spectrometric method.
This part is applicable to the determination of calcium oxide content and magnesium oxide content in limestone and dolomite, and also applicable to the determination of calcium oxide content and magnesium oxide content in metallurgical lime. Determination range (mass fraction) in complexometric titration method: calcium oxide content: >20%, magnesium oxide content: >2.5%; determination range (mass fraction) in atomic absorption spectrometric method: magnesium oxide content of 0.1% to 2.5%.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2007.2 General rules for the sampling and sample preparation of minerals in bulk-Manual method of sample preparation
GB/T 3286.2 Methods for chemical analysis of limestone and dolomite - Part 2: The determination of silicon dioxide content - The silicomolybdic blue spectrophotometric method and the perchloric acid dehydration gravimetric method
GB/T 3286.3 Methods for chemical analysis of limestone and dolomite - Part 3: The determination of aluminium oxide content - The chrome azurol S spectrophotometric method and the complexometric titration method
GB/T 3286.4 Methods for chemical analysis of limestone and dolomite - Part 4: The determination of iron oxide content - The o-phenanthroline spectrophotometric method and the flame atomic absorption spectrometric method
GB/T 6379.2 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 7728 Chemical analysis of metallurgical products - General rule for flame atomic absorption spectrometric methods
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
3 Complexometric titration method
3.1 Principle
Melt down the test portion with mixed flux of sodium carbonate - boric acid, and then leach with diluted hydrochloric acid. Take a part of the test solution, mask the iron, aluminum and manganese ions with triethanolamine, and titrate the calcium oxide with EDTA or EGTA standard volumetric solution in strong alkali medium with calcium carboxylic acid (calcium indicator) as the indicator. For high magnesium specimens, preset 90% to 95% EDTA or EGTA standard volumetric solution before adjusting the test solution to alkaline, so as to eliminate the influence of a large amount of magnesium. Take another part of the test solution, mask the iron, aluminum and manganese ions with triethanolamine, titrate the calcium oxide and magnesium oxide with EDTA standard volumetric solution in ammonia buffer solution with a pH value of 10 and acid chrome blue K and naphthol green B as mixed indicator, or mask the calcium with slightly excessive EGTA standard volumetric solution, and titrate the magnesium oxide with CyDTA standard volumetric solution.
The content of iron oxide and aluminum oxide in specimen is greater than 2.0% or the manganese oxide is greater than 0.10%. Precipitate and separate the iron, aluminium and manganese irons with sodium diethylamine dithiocarbamate (copper reagent), take the filtrate, and titrate the calcium oxide and magnesium oxide with EDTA or EGTA and CyDTA standard volumetric solutions.
3.2 Reagents
Unless otherwise stated, only recognized analytically pure reagents and distilled water above Grade III specified in GB/T 6682 or water with equivalent purity shall be used.
3.2.1 Mixed flux: grind two portions of anhydrous sodium carbonate and one portion of boric acid, and mix them well.
3.2.2 Hydrochloric acid (1+5).
3.2.3 Triethanolamine (1+4).
3.2.4 Ammonia water (1+1).
3.2.5 Potassium hydroxide solution (200g/L), stored in plastic bottles for more than 12h after being prepared prior to use.
3.2.6 Sodium diethylamine dithiocarbamate (copper reagent) solution (50g/L), prepared immediately before use.
3.2.7 Ammonia buffer solution (pH10): dissolve 67.5g ammonium chloride in water, add 570mL ammonia water (ρ=0.90g/mL), dilute to 1L with water, and mix well.
3.2.8 Calcium indicator (calcium carboxylic acid): grind 1g calcium indicator and 100g sodium chloride, and mix them well.
3.2.9 Acid chrome blue K-naphthol green B mixed indicator solution: dissolve 0.5g acid chrome blue K and 0.2 gnaphthol green B in water and dilute to 70mL with water.
Note: The ratio of acid chrome blue K to naphthol green B may be adjusted according to the color sensitivity of the indicator and the color discrimination ability of the operator.
3.2.10 Calcium oxide standard solution: weigh 0.8924g high purity calcium carbonate (with a purity of not less than 99.99%, dry at 105℃ to 110℃ for 1h before weighing and cool to room temperature in a dryer), put it in a 250mL beaker, add about 100mL water, and cover it with a watch glass. Slowly add 10mL hydrochloric acid (1+1) until the reagent dissolves, heat and boil to remove carbon dioxide, then take it down and cool to room temperature. Transfer the solution obtained into a 1,000mL volumetric flask, dilute it to the scale with water and mix well. This solution contains 0.50mg calcium oxide per 1.00mL.
3.2.11 Magnesium oxide standard solution: weigh 0.5000g high purity magnesium oxide (with a purity of not less than 99.99%, burn at 950℃ to 1,000℃ for 1h before weighing and then cool to room temperature in a dryer), put it in a 250mL beaker, add about 100mL water, and cover it with a watch glass. Slowly add 15mL hydrochloric acid (1+1) until the reagent dissolves, heat and boil, then take it down and cool to room temperature. Transfer the solution obtained into a 1,000mL volumetric flask, dilute it to the scale with water and mix well. This solution contains 0.50mg magnesium oxide per 1.00mL.
3.2.12 EDTA standard volumetric solution: [c(EDTA)=0.01mol/L]
3.2.12.1 Preparation
Weigh 3.72g EDTA into a 500mL beaker, add about 300mL water, heat at low temperature and stir continuously. After all the reagents are dissolved, cool to room temperature, transfer into a 1,000mL volumetric flask, dilute it to the scale with water and mix well.
3.2.12.2 Calibration of titer of calcium oxide by EDTA standard volumetric solution
Transfer three portions of 50.00mL calcium oxide standard solution (3.2.10) into 250mL or 500mL conical flasks respectively, add 2mL magnesium oxide standard solution (3.2.11), 5mL triethanolamine (3.2.3), 20mL potassium hydroxide solution (3.2.5) and about 0.1g calcium indicator (3.2.8), and titrate with EDTA standard volumetric solution (3.2.12.1) while shaking constantly until the solution changes from red to bright blue. The extreme difference of the volumes of EDTA standard volumetric solution consumed for three portions of calcium oxide standard solution shall not exceed 0.05mL, and the mean shall be taken.
The titer of calcium oxide by EDTA standard volumetric solution is calculated using Equation (1):
Foreword i
1 Scope
2 Normative references
3 Complexometric titration method
4 Flame atomic absorption spectrometric method
5 Test report
Annex A (Normative) Flow chart of procedure for acceptance of specimen analysis results
Annex B (Informative) Functional relationship of precision test and original data
