Aluminum Oxide :(AL2O3, MA=10194)
Alumina is included in the glaze composition when kaolin, pegmatite, nepheline syenite, aplite, feldspar, kaolin, talc, lepidolite, petalite ores found in nature are used in glazes because these ores contain alumina.
However, other raw materials other than feldspar, nepheline syenite and kaolin in the glaze structure are not used in glaze production due to the discontinuity in their chemical structures. Since the recent development of techniques used in ceramic production requires the production of glazes that can be tempered in much narrower ranges, the use of AL(OH)3 or calcined Alumina (AL2O3) is preferred due to the impurity content of these raw materials. Although it varies according to the glaze type, Alumina in glaze:
-Increases Viscosity
-Reduces tendency towards devitrification
-Reduces coefficient of expansion
-Increases strength of glaze
-Increases resistance to acids and bases
-Increases opacity
Aluminum oxide is used as abrasive and generally formed by the reaction of aluminum with oxygen easily. Melting point of 2072 °C and approximately 3 times that of pure aluminum. Aluminum gives good corrosion resistance. There are advantages and disadvantages of this feature. Wikipedia
Formula: Al2O3
Melting point: 2.072 °C
Molar mass: 101,96 g/mol
Density: 3.95 per g/cm3
Boiling point: 2.977 °C
Alumina, or aluminium oxide, aluminium is the largest cost item in connection with the production of. Alumina is required to produce metal of the highest quality high quality with low environmental impact. The production of approximately 100 million tons around the world, mostly from bauxite in the Bayer process is obtained.
Aluminum Oxide; It is widely used in the ceramic industry, it is used in glaze and frit recipes in different proportions according to the desired properties. Aluminum oxide glaze recipe varies between 5-15 according to the product properties. Generally, ground aluminum oxide -200 mesh is preferred.
Although it depends on the composition of the other raw materials used and the firing temperature, it increases the melting point of the glaze, provides surface opacity and also improves the wear resistance of the glaze. However, since it is a hard raw material, it must be thoroughly grinded. welcome
Aluminum oxide shows tight bonds because it forms tetrahedrates. Tight bonding brings together a tight structure. Tight structure reduces the thermal expansion coefficient and increases resistance to shock.
Features provided by aluminum glass and glassy system;
-Increases viscosity in molten systems at high temperatures.
-Glaze affects the crystallization behavior. Alumina (4-5%) above certain concentrations increases crystallization.
If the amount of aluminum is high in the formulation, the ripening temperature of the glaze increases and the firing cost increases due to the high melting temperature.
-Aluminium oxide is widely used in Frit and Pigment production.
-Manganese +Alumina = Pink color in Pigment Production, Chromium +Alumina =Green color
1. GENERAL INFORMATION
Aluminum (Al) is a light silvery colored substance with atomic number 13 and a density of 2.70 gr/cm3.
is metal. Aluminum, which is the most abundant element on earth after oxygen and silicon, is not found in pure form in nature, it is in the form of oxide and silicate compounds. Aluminum metal production is divided into primary and secondary production. Primary aluminum production is obtained from bauxite ores. Secondary aluminum is produced by recycling scrap aluminum.
90% of the world's bauxite reserve is used in the production of aluminum, the rest is used in the chemical, refractory, abrasive and cement industries. Bauxite ore used in aluminum production generally contains 30-60% aluminum and is considered to be of exploitable value. Bauxite ore deposits are generally operated near the surface, so they are operated by open pit mining.
There are various methods for obtaining pure aluminum from bauxite ore. Among these methods, the Bayer method discovered by Carl Bayer is still the most widely used method in the world. In the first stage of pure aluminum production from ore; Alumina (Al2O3) is obtained from bauxite ore by Bayer method, and pure aluminum is obtained from alumina by electrolysis method in the second step. About 4 tons of bauxite; 2 tons of alumina, 1 ton of metal
aluminum can be obtained.
Today, the demand for secondary aluminum obtained as a result of the reuse of scrap metal is increasing in parallel with high energy costs and environmentalist approaches. While energy costs constitute approximately 40% of the cost in primary aluminum production; In secondary aluminum production, the share of energy in total costs is around 5%.
There are various methods for obtaining pure aluminum from bauxite ore. Among these methods, the Bayer method discovered by Carl Bayer is still the most widely used method in the world. In the first stage of pure aluminum production from ore; Alumina (Al2O3) is obtained from bauxite ore by Bayer method, and pure aluminum is obtained from alumina by electrolysis method in the second step. About 4 tons of bauxite; 2 tons of alumina, 1 ton of metal
aluminum can be obtained.
Today, the demand for secondary aluminum obtained as a result of the reuse of scrap metal is increasing in parallel with high energy costs and environmentalist approaches. While energy costs constitute approximately 40% of the cost in primary aluminum production; In secondary aluminum production, the share of energy in total costs is around 5%.
Secondary aluminum is produced by recycling scrap aluminum in recycling facilities. All kinds of old packaging waste (beverage cans) made of aluminum and new residues from the production of end products are used as scrap. A significant part of the aluminum scrap supply is obtained from beverage cans, and the share of beverage cans in world secondary aluminum production varies between 25-55%. This share shows an increasing trend in parallel with the living standards and populations of the countries.
In recent years, the demand for secondary aluminum production has been increasing day by day all over the world. Because it requires much less energy use and creates less environmental problems. In developed countries, production of Al by recycling is higher. The USA meets most of its aluminum needs from recycling and produced 3.7 million tons of Al from recycling in 2017, of which 43% was obtained from old scrap and 57% from new scrap.