ALUMINIUMAluminum is a silvery white metal that berwaarna and quite mild which has a density of 2.7 g cm-3. The properties are owned aluminum, among others:
1. Lightweight, corrosion resistant and non-toxic it is widely used for household items like pots, pans and others.
2. Reflective, in the form of aluminum foil used for packaging food, drugs, and cigarettes.
3. Electrical conductivity two times greater than Cu, Al is used as a utility pole cable.
4. Al alloys with other metals to produce a strong metal such as Duralium (a mixture of Al, Cu, mg) for the manufacture of body peswat.
5. Al as a reductant agent for Aluminum oxide MnO2 and Cr2O3 are abundant in the earth's crust, which is about 7.6%. With the abundance of it, aluminum is the third leading element after oxygen and silicon, and is the most abundant metal element. However, Aluminum remains an expensive metal because of its processing difficult. Economically valuable mineral that aluminum is bauxite which is the only source of aluminum. Kriloit used in smelting aluminum, are used clay to make bricks, ceramics. In Indonesia, bauxite are found in Bintan island and in Tayan (West Kalimantan).
Processing Alumininum:
Aluminum is made by prosesHall lt-h erou found olehCh Arles M. Hall in the United States and Paul Heroult tahun1886. Aluminum and bauxite processing includes 2 stages:
1. Purification of bauxite for alumina meperoleh pure.
2. Consolidation / reduction of alumina electrolysis view
Purification of bauxite by the way:
a. Ba reacted dengana NaOH (q). Aluminum oxide will dissolve to form NaCl (OH) 4.
b. Solution was filtered and the filtrate containing NaAl (OH) 4 acidified with CO2 gas stream Al precipitate as Al (OH) 3
c. Al (OH) 3 filtered and then dried and heated in order to obtain Al2O3 not watery.
Aluminium ores are the major include:
• bauxite
• mica
• clay
Alumina Smelter:
Consolidation uses electrolysis cell consisting of graphite-coated metal container which also functions as a cathode (-) is anode (+) is graphite. Mixed Al2O3 with kriolit and AlF3 heated to melt and the temperature of 950 C and then dielektrolisis. Al is formed in the form of a liquid and accumulate in the bottom of the container and then released periodically into the mold to get the aluminum bar (ingot). Graphite anode continuously spent because reacts with O2 so it must be replaced from time to time. To get 1 kg of Al spent 0.44 graphite anode.
2Al2O3 +3 C
4Al + 3CO2
Some matte Al a major:
1. Bauxite (Al2O3. 2H2O)
2. Mika (K-Mg-Al-Slilkat)
3. Clay (Al2Si2O7.2H2O)
Aluminum exist in nature in the form of silicates and oxides, among other things:
• silicates such as feldspar, clay, mica
• kurondum such as anhydrous oxide (for emery)
• as a hydrate, eg bauxite
• kriolit such as fluoride.
Use of Aluminum:
Some use aluminum, among others:
1. Automotive industry sector, to create truck and automotive components.
2. to make the fuselage.
3. Housing construction sector; for doors and window frames.
4. Food industry sectors, for packaging various types of products.
5. Other sectors, eg for electric cables, furniture and handicrafts.
6. Membuattermit, namely a mixture of aluminum powder with a powder of iron (III) oxide, is used to weld steel in place, eg for connecting railroads.
Some Aluminum compounds are also many uses, among others:
1. Tawas (K2SO4.Al2 (SO4) 3.24H2O)
Alum has the chemical formula KSO4.AL2. (SO4) 3.24H2O. Alum is used to purify drinking water in water treatment.
2. Alumina (Al2O3)
Alumin adiedakan on alfa0allumina and gamma-allumina. Gamma-alumina is obtained from heating Al (OH) 3 under 4500C. Gamma-alumina is used for the manufacture of aluminum, for toothpaste, and industrial ceramics and glass industries. Alfa-allumina obtained from heating Al (OH) 3 at temperatures above 10000C. Alfa-allumina there as corundum in nature that are used for sandpaper or Grinding. Precious stones such as rubies, sapphires, ametis, and topaz is an alpha-allumina containing transition metal compounds that give color to the stones. Ruby colors include:
- Rubi red because they contain compounds of chromium (III)
- Sapphire blue because they contain compounds of iron (II), iron (III) and titan (IV)
- Ametis violet color because they contain compounds of chromium (III) and titan (IV)
- Topaz yellow because they contain iron (III)
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