(A) Overview 1. Properties of aluminum oxide of the formula A1 2 O 3; molecular weight 102; mp 2050 deg.] C; melting heat 21318 (25080) J / mol; density of 3.3-4.09 / cm 3; a boiling point of 2980 deg.] C; heat of vaporization 49282J/mol.
Aluminum has nine crystal forms: α, β, γ, δ, θ, κ, χ, η, Ï.
Some phases of hydrated alumina and alumina have strong chemical activity, can be dissolved in acid, and can also be dissolved in lye; while others have strong chemical stability (such as diaspore and alpha). -A1 2 O 3 ).
2. Quality Standards for Alumina The quality standards YB814-75 specified in China are shown in Table 1.
Table 1 Quality Standards for Alumina | ||||||
Product level | Code | Chemical composition /% | ||||
Al 2 O 3 > | Impurity content < | |||||
SiO 2 | Fe 2 O 3 | Na 2 O | Burning down | |||
First level | Al 2 O 3 -1 | 98.6 | 0.02 | 0.03 | 0.5 | 0.8 |
Secondary | Al 2 O 3 -2 | 98.5 | 0.04 | 0.04 | 0.55 | 0.8 |
Third level | Al 2 O 3 -3 | 98.4 | 0.06 | 0.04 | 0.6 | 0.8 |
Level four | Al 2 O 3 -4 | 98.3 | 0.08 | 0.05 | 0.6 | 0.8 |
Five levels | .Al 2 O 3 -5 | 98.2 | 0.1 | 0.05 | 0.6 | 1 |
Six levels | Al 2 O 3 -6 | 97.8 | 0.15 | 0.06 | 0.7 | 1.2 |
For countries with sand-like alumina, China has its own standards: China proposes the following indicators: particle size less than 44μm ≤ 15%; specific surface area ≥ 35m 2 / g; α-A1 2 O 3 content 20% - 35%.
The chemical composition (%) is as follows:
A1 2 O 3 SiO 2 Fe 2 O 3 Na 2 O Burning TiO 2 V 2 O 5 ZnO P 2 O5
≥98.5 ≤0.04 ≤0.04 ≤0.55 ≤1.0 <0.005 <0.003 <0.005 <0.003
China's specified aluminum hydroxide quality standard GB4294-84 is shown in Table 2.
Table 2 Quality Standards for Aluminum Hydroxide | |||||||
Product level | Code | Chemical composition /% | With water /% | ||||
Al 2 O 3 > | Impurity content < | ||||||
SiO 2 | Fe 2 O 3 | Na 2 O | Burning down | ||||
First level | Al ( OH ) 3 -1 | 64 | 0.03 | 0.03 | 0.45 | 35 | <15.0 |
Secondary | Al ( OH ) 3 -2 | 64 | 0.03 | 0.03 | 0.45 | 35 | <15.0 |
Third level | Al ( OH ) 3 -3 | 63.5 | 0.1 | 0.05 | 0.5 | 35 | <15.0 |
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