57
3.4.2 Aluminum Is an Excellent Material in Terms
of Recycling
Aluminum is produced from an ore called bauxite, which consists mainly of aluminum hydroxide (about 25% of the aluminum content). The energy used in creating
the product can be broken down into the following process: Mining (transport),
production of aluminum oxide from bauxite, reduction (electrolysis), and molding.
As described above, no energy is theoretically required for transport. The same
hold true for molding and processing. If a material is heated to near the melting
point, it becomes soft and can be easily molded. If heat is recovered when it cools,
this heat is the same amount as that required during the heating process. If this
recovered heat is used to heat the next sheet, and the process is repeated, no additional energy would be needed.
Cutting is among one of the processes, but if the material is melted and then
solidified in separate portions, the only energy required would be the heating process, and if that heat is recovered, no additional energy would be required. There
would be zero theoretical energy required for processing thick sheets into thin
sheets, cutting, machining, molding or processing.
To produce one ton of aluminum, 20 GJ of energy would be required in the process of producing aluminum oxide from bauxite. In the relevant reduction
(electrolysis) process, carbon electrodes that will wear out will be used, so together
with the power required in the process, 130 GJ of energy will be used. This brings
the total to 150 GJ. It is a high value that is five times the theoretical energy.
Recycling of aluminum is also very popular. According to the Japan Aluminum
Association, the energy used to produce regenerated mass that is made by recycling
scrap, etc. is about 3% of that required to produce new bullion from bauxite. Using
scraps is far more efficient than using ores, and it can be said that the scraps are an
excellent resource in terms of energy consumption.
3.4.3 Achieving Material Cycling of Rare Metals
The existence of urban mines is extremely important in low carbonization in the
monozukuri industry. Urban mine is a concept that was proposed more than 30 years
ago, but it came to be recognized by the general public only about 10 years ago
when the prices of rare metals that are indispensable to electronic devices such as
mobile phones and personal computers began soaring.
Rare metals are literally very scarce, and there are many mining areas that are
unevenly distributed. For example, small amounts of dysprosium are added to neodymium magnets used in hybrid and electric vehicle motors in to prevent deterioration of their magnetic force. Nearly all the dysprosium on the earth is in China, and
if imports stop, it will be no longer be possible to produce hybrid vehicles and
electric vehicles. Urban mines are important not only in terms of low carbonization
but also in terms of resource security.
3.4 Low-Carbon Technologies for Monozukuri
3.4.2 Aluminum Is an Excellent Material in Terms
of Recycling
Aluminum is produced from an ore called bauxite, which consists mainly of aluminum hydroxide (about 25% of the aluminum content). The energy used in creating
the product can be broken down into the following process: Mining (transport),
production of aluminum oxide from bauxite, reduction (electrolysis), and molding.
As described above, no energy is theoretically required for transport. The same
hold true for molding and processing. If a material is heated to near the melting
point, it becomes soft and can be easily molded. If heat is recovered when it cools,
this heat is the same amount as that required during the heating process. If this
recovered heat is used to heat the next sheet, and the process is repeated, no additional energy would be needed.
Cutting is among one of the processes, but if the material is melted and then
solidified in separate portions, the only energy required would be the heating process, and if that heat is recovered, no additional energy would be required. There
would be zero theoretical energy required for processing thick sheets into thin
sheets, cutting, machining, molding or processing.
To produce one ton of aluminum, 20 GJ of energy would be required in the process of producing aluminum oxide from bauxite. In the relevant reduction
(electrolysis) process, carbon electrodes that will wear out will be used, so together
with the power required in the process, 130 GJ of energy will be used. This brings
the total to 150 GJ. It is a high value that is five times the theoretical energy.
Recycling of aluminum is also very popular. According to the Japan Aluminum
Association, the energy used to produce regenerated mass that is made by recycling
scrap, etc. is about 3% of that required to produce new bullion from bauxite. Using
scraps is far more efficient than using ores, and it can be said that the scraps are an
excellent resource in terms of energy consumption.
3.4.3 Achieving Material Cycling of Rare Metals
The existence of urban mines is extremely important in low carbonization in the
monozukuri industry. Urban mine is a concept that was proposed more than 30 years
ago, but it came to be recognized by the general public only about 10 years ago
when the prices of rare metals that are indispensable to electronic devices such as
mobile phones and personal computers began soaring.
Rare metals are literally very scarce, and there are many mining areas that are
unevenly distributed. For example, small amounts of dysprosium are added to neodymium magnets used in hybrid and electric vehicle motors in to prevent deterioration of their magnetic force. Nearly all the dysprosium on the earth is in China, and
if imports stop, it will be no longer be possible to produce hybrid vehicles and
electric vehicles. Urban mines are important not only in terms of low carbonization
but also in terms of resource security.
3.4 Low-Carbon Technologies for Monozukuri