(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. 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%. 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 Sheet Metal Prototyping,Rapid Sheet Metal Prototyping,Rapid Sheet Metal Fabrication,Sheet Metal Rapid Prototype DONGGUAN TONJA INDUSTRIAL CO.LTD , https://www.tonjaism.com
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.
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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.
Alumina production (1)