GB/T 3286.2-2025 Methods for chemical analysis of limestone and dolomite—Part 2: Determination of silicon and aluminium content English, Anglais, Englisch, Inglés, えいご
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ICS 73.080 CCS D 52
National Standard of the People's Republic of China
GB/T 3286.2-2025 Replace GB/T 3286.2-2012, GB/T 3286.3-2012
Methods for Chemical Analysis of Limestone and Dolomite—Part 2: Determination of Silicon and Aluminium Content
Issued on 2025-08-29 Implemented on 2026-03-01
Issued by
State Administration for Market Regulation
Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Determination of Silicon Content: Silicomolybdenum Blue Spectrophotometric Method
5 Determination of Silicon Content: Perchloric Acid Dehydration Gravimetric Method
6 Determination of Aluminium Content: Chrome Azurol S Spectrophotometric Method
7 Determination of Aluminium Content: Complexometric Titration Method
8 Determination of Silicon and Aluminium Contents: Inductively Coupled Plasma Atomic Emission Spectrometric Method
9 Conversion Factors for Oxides
10 Test Report
Methods for Chemical Analysis of Limestone and Dolomite—Part 2: Determination of Silicon and Aluminium Content
1 Scope
This document describes the determination of silicon dioxide content by silicomolybdenum blue spectrophotometric method, perchloric acid dehydration gravimetric method, and inductively coupled plasma atomic emission spectrometric method; and the determination of aluminium oxide content by chrome azurol S spectrophotometric method, complexometric titration method, and inductively coupled plasma atomic emission spectrometric method.
This document is applicable to the determination of silicon dioxide and aluminium oxide contents in limestone, dolomite, and metallurgical lime. The determination ranges (mass fraction) are as follows:
Silicomolybdenum blue spectrophotometric method: silicon dioxide content 0.050% ~ 4.00%;
Perchloric acid dehydration gravimetric method: silicon dioxide content greater than 2.00%;
Inductively coupled plasma atomic emission spectrometric method: silicon dioxide content 0.070% ~ 3.50%;
Chrome azurol S spectrophotometric method: aluminium oxide content 0.010% ~ 0.75%;
Complexometric titration method: aluminium oxide content greater than 0.50%;
Inductively coupled plasma atomic emission spectrometric method: aluminium oxide content 0.040% ~ 1.00%.
2 Normative References
The following documents are indispensable for the application of this document. For dated references, only the editions cited apply. For undated references, the latest editions (including all amendments) apply.
GB/T 2007.2 General Rules for Sampling and Sample Preparation of Bulk Minerals—Manual Sample Preparation Method
GB/T 6379.1 Accuracy (Trueness and Precision) of Measurement Methods and Results—Part 1: General Principles and Definitions
GB/T 6379.2 Accuracy (Trueness and Precision) of Measurement Methods and Results—Part 2: Basic Method for Determining the Repeatability and Reproducibility of a Standard Measurement Method
GB/T 6682 Water for Analytical Laboratory Use—Specifications and Test Methods
GB/T 8170 Rules for Rounding off Numerical Values and Expression and Determination of Limit Values
GB/T 12806 Laboratory Glassware—Single-mark Volumetric Flasks
GB/T 12807 Laboratory Glassware—Graduated Pipettes
GB/T 12808 Laboratory Glassware—Single-mark Pipettes
JJG 768 Emission Spectrometers
3 Terms and Definitions
There are no terms and definitions to be defined in this document.
4 Determination of Silicon Content: Silicomolybdenum Blue Spectrophotometric Method
4.1 Principle
The test sample is fused with anhydrous sodium carbonate-boric acid mixed flux and leached with dilute hydrochloric acid. An aliquot of the test solution is taken, and in a hydrochloric acid medium of approximately 0.15 mol/L, ammonium molybdate reacts with silicic acid to form a silicomolybdic heteropoly acid. Oxalic acid-sulfuric acid mixed acid is added to eliminate interference from phosphorus and arsenic, and the heteropoly acid is reduced to silicomolybdenum blue with ammonium ferrous sulfate solution. The absorbance is measured at a wavelength of 680 nm using a spectrophotometer.
4.2 Reagents
Unless otherwise specified, only recognized analytical reagents and distilled water of at least grade 2 as specified in GB/T 6682 or water of equivalent purity shall be used in the analysis.
4.2.1 Mixed flux: Grind 2 parts by mass of anhydrous sodium carbonate and 1 part by mass of boric acid, and mix thoroughly.
4.2.2 Hydrochloric acid, ρ ≈ 1.19 g/mL.
4.2.3 Sulfuric acid, ρ ≈ 1.84 g/mL.
4.2.4 Anhydrous ethanol, ρ ≈ 0.80 g/mL.
4.2.5 Hydrochloric acid, 1+5 (1 volume of hydrochloric acid mixed with 5 volumes of water).
4.2.6 Hydrochloric acid, 1+14 (1 volume of hydrochloric acid mixed with 14 volumes of water).
4.2.7 Sulfuric acid, 1+8 (1 volume of sulfuric acid mixed with 8 volumes of water).
4.2.8 Ammonium molybdate solution, 60 g/L: Store in a plastic bottle; filter if necessary before use.
4.2.9 Oxalic acid-sulfuric acid mixed acid: Dissolve 35 g of oxalic acid (H₂C₂O₄·2H₂O) in 1000 mL of sulfuric acid (4.2.7).
4.2.10 Ammonium ferrous sulfate solution, 60 g/L: Dissolve 6 g of ammonium ferrous sulfate [Fe(NH₄)₂(SO₄)₂·6H₂O] in water containing 3–5 drops of sulfuric acid (4.2.3), dilute to 100 mL with water, and prepare immediately before use.
4.2.11 Silicon dioxide standard solution.
4.2.11.1 Weigh 0.2500 g of silicon dioxide (purity not less than 99.99%, ignited at 950 °C–1000 °C for 30 min and cooled to room temperature before weighing) into a platinum crucible. Add 3 g of mixed flux (4.2.1), mix well, and cover with another 1 g of mixed flux (4.2.1). Cover the platinum crucible with a lid (leaving a small gap), place it in a muffle furnace at 950 °C, and fuse for 10 min. Remove, cool to room temperature. Place the platinum crucible and lid in a polytetrafluoroethylene beaker containing 100 mL of hot water, heat gently to leach the melt until the solution is clear. Wash out the platinum crucible and lid with hot water, cool to room temperature. Transfer the solution to a 500 mL volumetric flask, dilute to the mark with water, mix well, and immediately transfer to a plastic bottle for storage. This solution contains 500.0 μg of silicon dioxide per 1.00 mL.
4.2.11.2 Pipette 50.00 mL of silicon dioxide standard solution (4.2.11.1) into a 500 mL volumetric flask, dilute to the mark with water, mix well, and immediately transfer to a plastic bottle. This solution contains 50.0 μg of silicon dioxide per 1.00 mL.
4.2.11.3 Pipette 20.00 mL of silicon dioxide standard solution (4.2.11.1) into a 500 mL volumetric flask, dilute to the mark with water, mix well, and immediately transfer to a plastic bottle. This solution contains 20.0 μg of silicon dioxide per 1.00 mL.
4.3 Instruments and Equipment
Ordinary laboratory instruments and equipment are used for the analysis. Single-mark pipettes, graduated pipettes, and single-mark volumetric flasks shall conform to the provisions of GB/T 12806, GB/T 12807, and GB/T 12808.
4.3.1 Analytical balance, with a division value of 0.1 mg.
4.3.2 Spectrophotometer.
4.3.3 Platinum crucible, 30 mL.
