How to determine the quality of brown corundum

To determine the quality of brown corundum, a systematic evaluation should be conducted based on its appearance characteristics, physical properties, chemical composition, and industry standards. The specific criteria are as follows:

1, Appearance features

• High quality color features: dark brownish red, dark brown or brownish brown, uniform color, good transparency (transparent or slightly blue when observed under sunlight) Poor quality features: exceptionally bright, black, rose red, may contain impurities or have high iron content. The particle shape should be regular hexagonal or spherical, uniform in size, without lumps or impurities; The finer and more uniform the particles, the higher the grinding efficiency.

 

 

2, Physical performance testing

• Hardness testing is conducted using a hardness tester (Vickers or Rockwell), and the compressive strength must meet the standard; Simple test: Hand pressed particles placed on white paper, fragile and cracked, indicating insufficient hardness. Impurity adsorption is achieved by using magnets to adsorb samples. The less magnetic material there is, the higher the purity of alumina, and the lower the content of impurities (such as iron). The wear resistance and ash content wear resistance can be compared with standard samples through a wear testing machine; Ash content test: It is best if there are no white floating objects on the water surface after soaking in clean water.

 

3, Chemical composition analysis

• Aluminum oxide (Al ₂ O3) content first grade product: Al ₂ O3 ≥ 94-95% (some high-purity products ≥ 96%); Second grade product: about 90-80%; Third grade product: lower content Impurities such as iron (Fe) and silicon (Si) need to be strictly controlled at low levels.
• Price reasonableness

 

The price of high-quality products is relatively high (reference: the market price of primary products is 4500-5500 yuan/ton), and low-priced products may be mixed with secondary raw materials.

Note: In industrial applications, first grade products are suitable for precision grinding and refractory materials; Second/third grade products are mostly used in ordinary industrial scenarios.

 

Guide to Avoiding Pits

• Beware of the low price trap: Products with black, opaque, or rose red colors are often of poor quality and have a high loss rate. Verification of purity: The manufacturer is required to provide a third-party component testing report, with a focus on verifying the content of Al ₂ O ∝ and impurities.