[China Aluminum Industry Network] Aluminum, the second largest metal material for national economic development, can be divided into two major categories: primary aluminum and recycled aluminum.
Primarya luminium is produced by Hall-Heroult (Na3AlF6)-alumina (Al2O3) fused-salt electrolysis method. Liquid aluminum at a temperature of about 950°C is siphoned. The method sucks from the electrolyzer into the lifting package, and then injects the mixing furnace after weighing. In 2011, the world's primary aluminum production was 43,000 kt, China's production was 19,650 kt, accounting for 45.7% of the world's total production. The world's primary aluminum production is expected to be about 44,720 kt in 2012, and China's production is about 21,550 kt, accounting for 48.2% of the world's total production in 2015. In the past, this trend will continue to be maintained.
Recycled aluminum is an ingot or melt aluminum that has been remelted and adjusted for composition with over 75% aluminum and aluminum alloy scrap (Scrapsofaluminium and aminium alloys). Secondary aluminum is also called secondary aluminum. The world production of recycled aluminum is about 14,000 kt.
Scrap Aluminum Classification Scrap aluminum can be divided into two categories: process wastes, wastes and waste products from various processes in the production and processing of semi-finished aluminum and processed parts. Most of them are consumed in the factory for alloy preparation. Seldom flows into the society or sells to other companies; aluminum scrap refers to aluminum and aluminum alloy components or entire products that are discarded after the end of their useful life, are collected and sorted and sold to aluminum processing plants, foundries, or recycled aluminum plants. The aluminum scrap mentioned means this category.
According to national GB/T13586-2006, scrap aluminum is divided into deformed aluminum and aluminum alloy scrap, cast aluminum scrap, aluminum and aluminum alloy scrap, aluminum and aluminum alloy scrap, and aluminum ash residue. Each category is divided into several groups. For example, there are 8 groups of deformed aluminum and aluminum alloy scraps: aluminum wires, aluminum cables, and aluminum conductive plates, including bright aluminum lines, mixed bright aluminum lines, old aluminum lines, old mixed aluminum lines, and wastes. Wires, new ACSR, old steel stranded conductors, conductive plates; aluminum foils, including new aluminum foil and old aluminum foil; aluminum cans, including new cans, old cans, cans, cans, cans, cans and cans; aluminum plate containing New PS substrate, old PS substrate, painted aluminum plate, aircraft aluminum plate, low copper aluminum plate, similar aluminum plate, mixed new aluminum plate, miscellaneous old aluminum plate; radiator plate is aluminum radiator plate; edge material is new edge material and mixed scrap material; Appliances refer to scrap aluminum consisting of pots, pots, and bottles.
There are five groups of cast aluminum alloy scraps: ingots, which are aluminum ingots cast from scrap aluminum, or ingots; the pistons include rodless aluminum pistons (waste aluminum consisting of clean aluminum pistons without tie rods), with Rod aluminum piston and clamped iron aluminum piston (aluminum scrap consisting of iron-containing aluminum piston); automotive aluminum castings; aircraft aluminum castings; and other similar aluminum castings (same grade, new, clean, uncoated aluminum) The aluminum scrap consists of castings, forgings, and extrusions) and mixed aluminum castings, which consist of a mixture of various clean aluminum castings (which may include automotive or Feco aluminum castings).
The third category is aluminum and aluminum alloy scrap, which is composed of the same type of aluminum scrap (aluminum scrap consisting of the same kind of brand-name, clean aluminum scraps) and mixed aluminum scrap (combined with various brands of clean, un-corroded aluminum alloys). Scrap aluminum) two groups.
The fourth category is aluminum and aluminum shards. There are two groups of aluminum shards and mixed shards. The former refers to scrap aluminum consisting of dry chips of aluminum and aluminum alloys. The latter consists of aluminum, copper, lead, zinc, stainless steel, nickel, and tin. Waste aluminium such as non-ferrous metals (which may be mixed with stones, glass, rubber, plastics, and wood).
The fifth category is aluminum ash slag, which is divided into three groups: slag (slag), which is aluminum or aluminum alloy waste aluminum formed during the smelting process, loose or blocky slag; furnace bottom agglomeration is Aluminium and aluminum alloy furnace bottom agglomeration waste aluminum; The third group is aluminum and aluminum alloy aluminum ash generated during the casting process.
No flammable, explosive, toxic, corrosive, or flanking material is permitted in the aluminum waste, and mixed medical waste or sealed containers are not allowed. Waste aluminum surface debris should be removed as much as possible. The larger form factor of the bulk aluminum scrap is negotiated by the supply and demand sides.
Imports and Exports of Aluminum Waste China is the world's largest net importer of aluminum scrap, and its export volume is negligible compared with imports. According to the annual report of the customs, China imported more than 5kt (import 5.490kt) since 1990 and imported 2,587.33kt in 2011. In the 22 years, it imported 21134.609kt of aluminum, with an average import volume of 960.66kt/a; export 140.016kt, The average export volume is 6.364kt/a, the total net import volume is 20994.593kt, and the average net import volume is 954.3kt/a. The average annual growth rate of net imports during this period was 70.69%.
The annual average rate of net imports of aluminum scrap during the period from 1990 to 2011 is so large that China's demand for aluminum is strong, indicating that China's economy is undergoing a period of sustained high growth. In 2011, the net import of scrap aluminum showed a negative growth (-5.90%), which is also an iconic figure, at least two points: First, China's GDP growth rate began to slow down, and second, China's recyclable aluminum scrap increased.
Recyclable waste aluminum Knows how much aluminum and aluminum alloy waste is called scrap aluminum. Among the metals used in the construction of the national economy, the recyclability of aluminum is high. This has four meanings. The first is that aluminum has strong corrosion resistance, and it hardly corrodes in the atmosphere, but only on the surface. The formation of a thin film layer of aluminum oxide film, actually this layer of aluminum oxide film is thinner than the flap, its thickness is only about 5nm (nanometer), its quality is negligible, while it is very dense, oxygen permeability, both Oxygen can be prevented from entering, which means that once it is formed, it will protect the aluminum from oxidation and its formation rate will be extremely fast. Once the “fresh†aluminum is exposed to the atmosphere, it will immediately undergo oxidation reaction with oxygen to form an oxide film. . If the oxide film on the aluminum is destroyed, a new film will be formed as it is. This means that the surface oxide film of aluminum and aluminum alloy has a strong "self-healing" ability; the second is to say that the aluminum scrap is being remelted during the remelting process. The energy consumption in the process is low and the burning loss is small. The energy consumption of aluminum scrap in the remelting process is equivalent to about 5% of the total energy consumption of the primary aluminum extraction (the sum of the energy consumption of the bauxite mining, alumina extraction, and primary aluminum production). , that is about 870kWt (t recycled aluminum); the waste discharged is less than 1/25 of the original aluminum extraction, social benefits are very significant, 1t alumina needs 2t bauxite to produce solid waste - red mud about 1t Although red mud is not a toxic substance, it is harmful. It is an alkaline substance. The infiltration of alkalis into the farmland will cause harm and pollute the environment. At the same time, it needs a lot of space to store it. Breaking dams results in catastrophic consequences. At the same time, it requires a large area of ​​valuable farmland resources. During the alumina extraction process, a large amount of water is consumed, and the discharged water is polluted to varying degrees. When aluminum is electrolyzed, 1 ton of primary aluminum consumes about 450 kg of carbon. , charcoal becomes CO2 and CO to GHG emissions form into the atmosphere. Fluorine-containing gases are emitted when electrolytically producing aluminum. Although most of these oxides are recovered, they can be discharged into the atmosphere in a non-negligible amount, causing harm because of the toxicity of fluoride and aluminum scrap. When re-melting natural gas or diesel, only CO2 is released. If the combustion is not complete, it will also release a small amount of CO, but their emission is much less than that of electrolysis. Fourth, the quality of recycled aluminum produced by modern technology and equipment can be completely satisfied. The quality of primary aluminum is comparable. For example, a 6063 alloy ingot smelted from waste aluminum can be used to extrude new 6063 alloy building profiles. The use of Al99.7E for remelting aluminum alloys with the use of waste electrical wires for smelting of conductive aluminum alloys There is no difference in ingot production.
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