What is the bulk density of alumina?

Alumina, also known as bauxite, has a molecular weight of 102 and is a white amorphous powder, commonly known as bauxite.

It is an atomic crystal with valence bond of * * *, melting point of 2050℃, boiling point of 3000℃ and true density of 3.6g/cm.

Good fluidity, insoluble in water, soluble in molten cryolite. It is the main raw material for aluminum electrolysis production.

β-alumina δ-alumina V- alumina A- alumina has four isomers, mainly α-alumina and γ-alumina, which can be extracted from bauxite in industry.

Name alumina; Corundum; White jade; Ruby; Sapphire; Corundum powder; corundum

ChemicAl formula al? o？ The appearance is white crystalline powder or solid.

physical quality

The formula is101.96amu.

Melting point 2303 K

Boiling point 3250 K

The true density is 3.97 g/cm3.

Loose density: 0.85g/mL(325 mesh ~0)0.9g/mL( 120 mesh ~325 mesh).

Trilateral system of crystal structure

Thermochemical properties

fH0liquid？ 1620.57 kj/mol

δfh0 solid? 1675.69 kj/mol

S0 liquid, 1 bar 67.24 joules/mole? K

S0 solid 50.9 J/mol? K

safe

Low intake risk

Inhalation may cause irritation or lung injury.

Low skin risk

Low eye risk

Unless otherwise specified, SI units and standard air temperature and pressure are used.

Alumina is a compound of aluminum and oxygen, and its molecular formula is Al2O3. It is also called bauxite in mining, ceramics and materials science.

Emergency treatment

Isolate the leaking and polluted areas and restrict access. It is recommended that emergency personnel wear dust masks (full face masks) and protective clothing. Avoid dust, carefully sweep it up, put it in a bag and move it to a safe place. If there is a large amount of leakage, cover it with plastic sheets and canvas. Collect and recycle or transport to the waste disposal site for treatment.

prepare

Amorphous white alumina powder can be obtained by intense heating of aluminum hydroxide. 2Al(OH) 3 → Al 2 O 3 +3H 2 O

use

1. Ruby and sapphire are mainly composed of alumina, so they show different colors because of other impurities. Ruby is red because it contains chromium oxide, while sapphire is blue because it contains iron oxide and titanium oxide.

2. Among the main components of bauxite, alumina has the highest content. In industry, bauxite is purified into alumina by Bayer process, and then transformed into metallic aluminum by Hall-Herout process.

3. Alumina is the reason why metallic aluminum is not easily corroded in air. Pure aluminum easily reacts with oxygen in the air to form a thin aluminum oxide film covering the aluminum surface exposed to the air. This alumina film can prevent aluminum from being further oxidized. The thickness and performance of this oxide film can be enhanced by a treatment process called anodic treatment (anodic corrosion protection).

Aluminum is a good conductor of electricity and heat. Silicon carbide, the crystalline form of aluminum, is suitable for grinding materials and cutting tools because of its high hardness.

5. Alumina powder is often used as a carrier for chromatographic analysis.

6. In August, 2004, scientists working in American 3M Company developed an alloy made of aluminum and rare earth elements, which was used to make strengthened glass called transparent alumina.

Data The hardness of corundum powder can be used as abrasive, polishing powder and alumina sintered at high temperature, which is called artificial corundum or artificial gem, and can be used to manufacture diamonds in mechanical bearings or watches. Alumina is also used as a high-temperature refractory to make refractory bricks, crucibles, porcelain and artificial gem. Alumina is also the raw material for aluminum smelting. γ-Al2O3 can be prepared by calcining aluminum hydroxide. γ-Al2O3 has strong adsorption and catalytic activity, and can be used as adsorbent and catalyst. The main component of corundum is α-Al2O3. Bucket or conical triangular crystal. Have glass luster or diamond luster. The density is 3.9 ~ 4. 1g/cm3, the hardness is 9 and the melting point is 2000 15℃. Insoluble in water, acid and alkali. High temperature resistance. Colorless and transparent is called white jade, reddish and containing trace trivalent chromium is called ruby; Blue containing ferrous iron, ferric iron or tetravalent titanium is called sapphire; Dark gray and dark black containing a small amount of ferroferric oxide are called corundum powder. It can be used as bearings for precision instruments, diamonds for clocks and watches, grinding wheels, polishing agents, refractories and electrical insulators. Colored gems that can be used for decoration. Artificial ruby single crystal can be used as laser material. In addition to natural minerals, it can also be made by melting aluminum hydroxide with hydrogen-oxygen flame.

The chemical formula of alumina is Al2O3 and its molecular weight is 10 1.96. Main components of bauxite. White powder. It has different crystal forms, the common ones are α-Al2O3 and γ-Al2O3. In nature, corundum is α-Al2O3 with hexagonal close-packed crystals. α-Al2O3 has a melting point of 20 15 15℃, a density of 3.965g/cm3 and a hardness of 8.8, and is insoluble in water, acid or alkali. γ-Al2O3 is a cubic closely packed crystal, insoluble in water, but soluble in acid and alkali, and is a typical amphoteric oxide.

Al2O3+6H+=2Al3++3H2O

Al2O3+2OH-=2AlO2-+H2O

Preparation and application of alumina;

1, method for manufacturing alumina coating with alpha-type crystal structure as main body, alumina coating with alpha-type crystal structure as main body and coating containing the coating.

2. Method for producing α -alumina powder

3. Method for producing alpha-alumina powder and alpha-alumina powder obtained by the method.

4. α -alumina powder and its production method

5. α -alumina powder and its production method

6. α -alumina and its production method

7. Preparation method of α -alumina particles

8. A preparation method of α -alumina nano powder

9. α -alumina fine powder and its preparation method

Method for producing 10 and alpha-alumina powder

1 1 and preparation method of beta-alumina

Preparation method of 12 and γ-alumina

13, θ-alumina in-situ coated monolithic catalyst carrier

Method for jointly producing alumina and calcium aluminate cement by 14 and Bayer process

Fluidization process of red mud suspension in Bayer alumina production.

Aluminum burns in air and combines with oxygen to produce alumina. The chemical equation can be written as △

4Al+3O2= ignition ==2Al2O3

CASNo.: 1344-28- 1

EINECS login number: 2 15-69 1-6.

What is alumina?

Pure alumina is white amorphous powder, commonly known as bauxite, with a density of 3.9-4.0g/cm3, a melting point of 2050℃ and a boiling point of 2980℃. It is insoluble in water. There are two main varieties of alumina, α and γ, which can be extracted from bauxite in industry.

Bauxite (Al2O3 3H2O and Al2O3 3H2O) is the main mineral of aluminum in nature. After crushing, it was impregnated with high-temperature sodium hydroxide solution to obtain sodium aluminate solution. Filtering to remove residues, cooling the filtrate, adding aluminum hydroxide crystals, and after stirring for a long time, decomposing the sodium aluminate solution to separate out aluminum hydroxide; After separation and washing, the precipitate was calcined at 950- 1200℃ to obtain α -alumina powder, and the mother liquor could be recycled. This method was invented by Austrian scientist K.J.Bayer in 1888, and it is still the main method for industrial production of alumina, which is called "Bayer method".

In the lattice of α-alumina, oxygen ions are packed in hexagonal shape, and Al3+ is symmetrically distributed in the octahedral coordination center surrounded by oxygen ions, so the lattice energy is very large, so the melting point and boiling point are very high. Alpha alumina is insoluble in water and acid, also known as alumina in industry, and is the basic raw material for manufacturing metallic aluminum. It is also used to make various refractory bricks, refractory crucibles, refractory pipes and high temperature resistant experimental instruments; It can also be used as abrasive, flame retardant, filler, etc. High purity α -alumina is also the raw material for producing artificial corundum, artificial ruby and sapphire. It is also used to produce substrates for modern large-scale integrated circuits.

Aluminum hydroxide was dehydrated at 140- 150℃ to prepare γ alumina. It is also called activated alumina and aluminum glue in industry. In its structure, oxygen ions are closely packed in the center of the cube, and Al3+ is irregularly distributed in octahedral and tetrahedral spaces surrounded by oxygen ions. γ alumina is insoluble in water, but soluble in strong acid or alkali solution. When heated to 1200℃, it is completely converted into α -alumina γ -alumina is a porous substance with an internal surface area of hundreds of square meters/gram, high activity and strong adsorption capacity. Industrial products are usually colorless or pinkish cylindrical particles with good pressure resistance. It is often used as adsorbent, catalyst and catalyst carrier in petroleum refining and petrochemical industry. In industry, it is a deacidifying agent for transformer oil and turbine oil, and also used for chromatographic analysis; It is a neutral and strong desiccant in the laboratory, and its drying capacity is no less than that of phosphorus pentoxide. Heating at 175℃ for 6-8 hours after use can be recycled.

At present, the alumina produced by Bayer process accounts for more than 90% of the world total output. Most alumina is used to make metallic aluminum, and less than 10% is used for other purposes.

Electrolytic alumina:

The main process of industrial large-scale production of electrolytic aluminum is molten salt electrochemical process, which can be expressed by simple chemical formula as follows:

Molten salt electrolysis

Main reaction: Al2O3+C —→ Al+CO2 ↑+Co ↑ (1).

Anode 960 ~ 990℃ cathode

Side effects: AlF3+C→Al+CF3 (2)

Na3AlF3+C →Al+NaF+CF4+F2 (3)

NaF+C → Na+CF4 (4)

[Edit this paragraph] Development strategy of alumina enterprises

In the case of rising energy prices, the major aluminum companies in the world began to turn their attention to building aluminum production bases to the Middle East and Africa where electricity prices are low. Ensuring the price competitiveness of aluminum production by reducing the electricity charges related to production costs has become the focus of attention of major aluminum companies in the world. From the perspective of domestic policy, the orientation of national industrial policy for aluminum industry is to meet domestic demand, and there will be policy differences between high-tech products and low-tech products. Therefore, for the policy and structural turning point of the industry, upstream and downstream aluminum enterprises should focus on the domestic market and expand the application of aluminum in the domestic market; Expand the application field of aluminum, improve the added value of aluminum application and enhance the technical content. In addition, aluminum production enterprises should pay more attention to the development trends of related industries and downstream industries, especially in transportation, electric power, packaging, household appliances and other industries, and at the same time increase investment in technology research and technology.

Electrolytic aluminum electrolytic aluminum is aluminum obtained by electrolysis.

Importance is carried out by this equation: 2Al2O3==4Al+3O2.

Anode: 2o2ˉ-4eˉ= O2↓

Cathode: Al3+ +3eˉ=Al

Aluminum electrolysis process flow chart

Aluminum electrolysis process:

Modern aluminum industry adopts cryolite-alumina molten salt electrolysis method. Molten cryolite is used as solvent, alumina as solute, carbon as anode and aluminum liquid as cathode. After introducing strong direct current, electrochemical reaction, namely electrolysis, is carried out at the two poles in the electrolytic cell at the temperature of 950-970℃. The anode products are mainly carbon dioxide and carbon monoxide, which contain a certain amount of harmful gases such as hydrogen fluoride and solid dust. In order to protect the environment and human health, it is necessary to purify the anode gas to remove harmful gases and dust, and then discharge them into the atmosphere. The cathode product is aluminum liquid, which is pumped out of the tank by vacuum bag, sent to the casting workshop, purified and clarified in the holding furnace, and cast into aluminum ingots or directly processed into wire blanks and profiles. The production process is as follows:

Aluminum fluoride carbon anode DC

↓ ↓ ↓ ↓

↓

Waste gas anode gas electrolytic cell.

↑ ↓ ↓

Aluminum liquid waste gas/gas purification

↓ ↓

Purification and clarification of recovered fluoride.

↓ ↓ ↓

Return to electrolyzer

Casting, rolling or casting

↓ ↓

Aluminum ingot wire blank or profile

[Edit this paragraph] Development of electrolytic aluminum industry

It took nearly 40 years from the first electrolytic aluminum plant in China, Fushun Aluminum Plant 1954 to 1992, and the output of electrolytic aluminum in China only exceeded10.96 million tons. Even in the 1990s when aluminum was the priority, the output of electrolytic aluminum in China increased from 65,438+10.87 million tons in 1995 to 2.83 million tons in 2000, and it took five years, with an average annual growth rate of 1 1.2%.

From 2002 to 2007, the average annual growth rate of electrolytic aluminum production in China reached 29.7%, which surprised the world. The annual increase of electrolytic aluminum output exceeds 1 10,000 tons. At the same time, since the growth rate of global electrolytic aluminum production in 2007 has exceeded the growth rate of consumption by 2 percentage points, the annual supply has exceeded 400,000 tons. Similar to the global market, the domestic electrolytic aluminum market in 2007 was also oversupply, and it is estimated that the market surplus is about 300,000 tons. Since the beginning of this year, China's economic development has slowed down and its demand for aluminum has decreased. Since August, the aluminum inventory in the domestic market has been increasing, and now it has exceeded 400,000 tons. Due to the depression of the real estate industry, the sales of aluminum profiles, which account for about 35% of the total consumption, are blocked, and the automobile industry is also a major consumer of aluminum in recent years. However, due to the slowdown in growth, the demand for aluminum decreased, and the sales of aluminum wheels and their alloys decreased significantly.