GB/T 28629-2024 Methods for chemical analysis of free silicon dioxide in cement clinker
1 Scope
This document describes chemical analysis methods for determination of free silicon dioxide in cement clinker by phosphoric acid decomposition - hydrofluoric acid treatment weighing method, phosphoric acid decomposition - silicomolybdenum blue spectrophotometric method and phosphoric acid decomposition - potassium fluosilicate volumetric method.
This document is applicable to the determination of free silicon dioxide in cement clinker.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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 2007.1 General rule for the sampling and sample preparation of minerals in bulk - Manual sampling method
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
JJG 196 Working glass container
3 Terms and definitions
No terms and definitions are listed in this document.
4 General requirements for test
4.1 Number of tests and requirements
Each sample shall be independently determined twice by the method specified in this document. The average value of the two test results shall be used to represent the determination results, and the numerical values shall be rounded off according to GB/T 8170.
4.2 Expression of masses, volumes, volume ratios and titers
Express masses in “grams (g)” to the nearest of 0.000 1g, volumes from burettes in “milliliters (mL)” to the nearest of 0.01mL, and titers in “milligrams per milliliter (mg/mL)”. The results of titers shall be rounded off to four decimal places. Each analysis result shall be calculated as a mass fraction, and the analytical value shall be expressed as a percentage (%) to the last two decimal places.
4.3 Blank test
Carry out a blank determination without a sample, following the same procedure and using the same amounts of reagents. Correct the results obtained for the analytical determination accordingly.
4.4 Ignition
Put the filter paper and the precipitate or insoluble slag into a pre-ignited and constant crucible, cover the crucible cover (with gaps). To avoid flame production, slowly dry and ash them in an oxidative atmosphere until no black carbon particles remain. Then, put them into a high-temperature furnace and ignite them at the specified temperature. Then allow to cool to the room temperature in a desiccator, and weigh it.
4.5 Constant mass
After the first ignition, cooling and weighing, determine constant mass by making successive 15 min ignitions of the vessel or sample followed each time by cooling and then weighing. Constant mass is reached when the difference between two successive weights is less than 0.000 5g.
Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 General requirements for test 5 Reagents and materials 6 Apparatus 7 Preparation of samples 8 Determination of free silicon dioxide — Phosphoric acid decomposition - hydrofluoric acid treatment weighing method (reference method) 9 Determination of free silicon dioxide — Phosphoric acid decomposition - silicomolybdenum blue spectrophotometric method (alternative method) 10 Determination of free silicon dioxide — Phosphoric acid decomposition - potassium fluosilicate volumetric method (alternative method) 11 Permissible deviation
