GB/T 9489-2024Methods for chemical analysis of alundum powder (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part

1.Structure and drafting rules for standardization documents" Drafting is required. This document replaces GB/T 9489-2008 "Chemical analysis method of corundum powder". Compared with GB/T 9489-2008, in addition to the structural adjustment In addition to editorial changes, the main technical changes are as follows: Added "Warning" (see Warning);

a) The concentration of "Silicon Dioxide Standard Solution" and the volume of the volumetric flask during the preparation process have been changed (see 5.3.8,

5.3.8 of the.2008 edition);

b) The flame type of the elements "Ca, Mg" has been changed (see 6.4.4,

6.4.4 of the.2008 edition);

c) Changed the "Test Solution Preparation" in the atomic absorption spectrophotometry (see 6.5.1,

6.5.1 of the.2008 edition);

d) The order of adding "borax and sodium carbonate mixed flux" has been changed (see 7.5.1, 9.5.2.1, 7.5.1,

9.5.2.2 of the.2008 edition). 9.5.2.1);

e) Added the requirement of "storage temperature" of silica standard solution (see 9.5.1, 9.5.2.2);

f) The determination range of titanium dioxide colorimetric method has been changed (see 10.1,

10.1 of the.2008 edition);

g) The volume of titanium dioxide standard solution to be pipetted in "Drawing the working curve" has been changed (see 10.5.1,

1 Scope

China's national methods for the chemical analysis of fused alumina powder. Fused alumina - corundum - is made by melting bauxite or alumina in an electric arc furnace and crushing the resulting crystal mass, and it is the abrasive of grinding wheels, sandpaper and blasting media, as well as a refractory raw material. Its performance rests on what accompanies the alumina rather than on the alumina itself. Sodium is the impurity that matters most: sodium oxide converts corundum into beta-alumina, which is softer and cleaves differently, so a high-soda material grinds poorly whatever its assay says. Silica and titania affect the crystal size and toughness, iron oxide contaminates what is ground, and chloride and sulfur come from the process. The pH and loss on ignition characterise the surface, which determines how the grain bonds into a wheel. The standard describes the determination of aluminium, calcium, magnesium, silicon, iron and titanium oxides, potassium and sodium oxides, chloride, carbon and sulfur, the pH value and the loss on ignition, and applies to corundum powder of at least 90 per cent alumina.

This document describes the content of aluminum oxide, calcium oxide, magnesium oxide, silicon dioxide, iron oxide, titanium dioxide, Determination methods for potassium, sodium oxide, chloride ion, carbon and sulfur, pH value and loss on ignition. This document is applicable to the chemical analysis of corundum powder with an aluminum oxide content (mass fraction) of not less than 90%.

2 Normative references

The contents of the following documents constitute the essential clauses of this document through normative references in this document. For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies. in this document.

GB/T 4676 Sampling method for common abrasives

GB/T 6682 Specifications and test methods for water used in analytical laboratories

GB/T 8170 Rules for rounding off values and expression and determination of limit values

3 Terms and definitions

There are no terms or definitions that require definition in this document.

4 General requirements

4.1 The specifications of water used in solution preparation and analysis should conform to Grade III or above water specified in GB/T 6682.

4.2 Unless otherwise specified, the purity of the reagents used in the determination should be better than analytical grade. When a standard solution is prepared with a metal, its purity should be better than 99.99%.

4.3 Except for specially specified solvents, all solutions used in analysis are aqueous solutions.

4.4 When conducting the "constant weight" test, the burning or drying, taking out, drying, cooling, and weighing steps should be repeated at the same temperature. Continue until the difference between the two weighings is no more than 0.000 2 g.

4.5 The concentration of the standard titration solution is expressed as c(A)=mol/L or T(B)/(A)=mg/mL. When calibrating its concentration, Carry out more than three determinations and conduct blank test comparison. The relative error of the concentration obtained should not be greater than 0.20%. The arithmetic mean of the results is taken. And rounded to 4 decimal places.

4.6 When preparing and storing reagent solutions, reagents that are corrosive to glass should be stored in plastic containers, and reagents that are easily decomposed should be stored in Store in brown containers and indicate storage precautions and storage time.

4.7 A parallel blank test should be carried out for each test, and the analytical results should be corrected based on the blank test results.

4.8 The samples shall be sampled and divided according to GB/T 4676, and then ground with a corundum mortar to a particle size of no more than 75 µm. Mix well, put into sample bag, dry in electric drying oven at 105°C110°C for 1 h2 h, take out, put into desiccator and cool to room temperature for use. The mass of the analytical sample should not be less than 20 g.