Since the beginning of the new century, in order to further make up for the shortage of mineral resources in China, the tension between supply and demand has been alleviated. Under the guidance of a series of national support and regulation of industrial development policies, China’s renewable metal industry has made full use of international resources to develop rapidly, and the proportion of trade accounts for global non-ferrous metal scrap. More than half of the countries or regions that have allocated resources across the country have reached more than 80. The cumulative import of copper and aluminum scrap has exceeded 100 million tons, and nearly 70 million tons of recycled non-ferrous metal products have been produced. Among them, the recycled copper produced by the use of imported copper-containing scrap accounts for more than 70% of the total; the recycled aluminum produced by the imported aluminum-containing waste accounts for nearly 55% of the total. It has realized the goal of rapid utilization of international non-ferrous metal scrap resources to expand China’s renewable non-ferrous metal industry, and made positive contributions to the non-ferrous metal materials to meet the needs of economic and social development.
Since last year, the state has further strengthened the construction of ecological civilization, completely banned the entry of foreign garbage, and promoted the reform of the import management system for solid waste. Recently, the Sino-US trade war has restricted the import of aluminum alloy scrap, which has seriously affected enterprises that have long relied on imported waste for production. . Faced with these challenges, we should recognize the supply pattern of the domestic aluminum scrap market, improve the efficiency of resource utilization, eliminate the impact of trade wars, clear the blurred line of sight, and recover the missing and wasted resources. Many aluminum scrap resources quickly returned to the production enterprises, making China’s recycled aluminum industry shift from import-led development to self-sufficiency and healthy development.
Aluminum scrap market
Aluminum can be recycled indefinitely, and the energy required to recover aluminum is about 95% lower than that of producing primary aluminum, reducing emissions by more than 90%. Since its production began in 1888, aluminum has produced about 1 billion tons, of which 75% are still being recycled. Since aluminum is processed into consumer or industrial products according to market needs, aluminum scrap is composed of two new waste forms: “new” and “old”. Aluminum produces new waste during the forging and casting of products, recycling old waste from end-of-life products or all types of waste products. There is also a dregs (aluminum ash) that is often overlooked and that is less important.
Due to the high economic value of aluminum, the recovery rate of aluminum has been very high. The recovery rate of aluminum in the construction and transportation and packaging industries is up to 95%, and the recycling of foil in the packaging industry is also increasing. In 2017, the global total aluminum output was 94.848 million tons, of which 30,866,000 tons of metal aluminum (recycled aluminum or secondary aluminum) was used for waste production, accounting for 32.7%, and alumina production (primary aluminum) was 63.826 million tons, accounting for 67.3%.
Global production and growth trends of primary and recycled aluminum
Obviously, countries with high aluminum consumption are also the countries with the largest amount of aluminum scrap. At present, the world’s aluminum scrap is mainly concentrated in the three regions of the United States, the European Union and China; a large part of high-quality waste in Europe and America is recycled internally to make new aluminum. Due to the relatively short service life of packaging and automobiles, the recycling rate and recycling rate of scraps are fast. Therefore, the excess is exported. In the past, China was the main importer of aluminum scraps for broken cars in Europe and America.
The United States is the region with the longest history of aluminum production and consumption, and the world’s most abundant aluminum scrap resource. In addition to meeting the waste required for secondary aluminum production in China, it also exports 2 million tons of waste every year, accounting for one-third of the total global waste supply. In 2016, the total consumption of metal aluminum in the United States was 9.538 million tons, of which 5.325 million tons of recycled aluminum, accounting for 55.8% of total aluminum metal consumption. In 2016, the United States produced 6.508 million tons of recycled aluminum. Among them, the use of new waste production of 1.972 million tons, accounting for 30.3%, the use of old waste production of 4.536 million tons, accounting for 69.7%.
The EU – accounting for more than 15% of global aluminum consumption, aluminum consumption is mainly concentrated in Germany, the United Kingdom, France, Italy, which is the location of the world’s largest car manufacturer, the development of the global aluminum industry to a large extent Depends on this market. In 2016, the total consumption of metal aluminum in the EU was 10.231 million tons, of which 4.62 million tons were recycled aluminum, accounting for 44.8% of the total metal consumption. In 2016, the EU produced 5.288 million tons of recycled aluminum. Among them, the use of new waste production of 1.767 million tons, accounting for 33.4%, the use of old waste production of 3.521 million tons, accounting for 66.6%.
China – is the world’s largest aluminum producer. Since 2001, aluminum production has been ranked first in the world. In 2016, primary aluminum production accounted for 54.4% of the world’s total, and aluminum consumption totaled 42.518 million tons, including 0.952 million tons of recycled aluminum. , accounting for 23.4% of total metal consumption. In 2016, China produced 8.507 million tons of recycled aluminum. Among them, the use of old waste production of 3.06 million tons, accounting for 36%, the use of new waste production of 5.45 million tons, accounting for 64%.
Neglected and forgotten facts
As China’s metal aluminum deposits continue to increase, China’s aluminum alloy scrap production is also growing. From 2001 to 2016 alone, China has produced 230 million tons of electrolytic aluminum, with a per capita consumption of 24 kilograms and a per capita reserve of 130 kilograms. The import volume of aluminum alloy scrap decreased from 2.85 million tons in 2010 to 1.92 million tons in 2016, and the import volume was less than 30% of the total waste supply of 7.45 million tons.
Although the import of waste has been decreasing year by year, some cases have been neglected. That is, China has entered the peak period of scrapping of aluminum since 2010. It is currently the fastest period of waste growth, in which forged aluminum alloy waste accounts for more than 60%. Aluminum alloy waste accounts for about 30%, and the total amount exceeds 10 million tons. In theory, China no longer needs to import ordinary waste aluminum alloy scraps at this stage for replenishment. However, the actual situation is that there is no separation between the old and new waste production modes in China, and a large amount of deformed aluminum alloy waste and new waste are used as waste. The diluted aluminum alloy is produced into a common cast aluminum alloy ingot. This has contributed to the continuous expansion of the production capacity of cast aluminum alloys and the import of waste aluminum alloy materials. Obviously, if the deformed aluminum alloy scrap has an advanced and standardized circulation system, it is an indisputable fact that it is impossible to produce ordinary cast aluminum alloy by using the raw aluminum as the waste material of the waste aluminum.
Aluminum produces slag during smelting, processing and recycling. In 2017, China’s aluminum slag is estimated to be more than 4.2 million tons, of which the metal aluminum content exceeds 2.2 million tons. If processed by international advanced technology, 98% (2.156 million tons) of aluminum can be recycled, and the remaining oxides 100% (2.044 million tons) can be converted into green industrial raw materials for recycling. At present, the domestic technology is backward, the recovery rate of aluminum is less than 55%, and the technology of harmless resource treatment of oxides is still blank. That is to say, in 2017, only 2.2 million tons of aluminum was recovered in China’s 4.2 million tons of aluminum slag, with 990,000. Tons of aluminum have become oxides, and the total amount of hazardous waste has increased by 2.99 million tons from 2 million tons. According to the estimated 15,000 tons of aluminum, the direct loss of the whole industry is 15 billion yuan. This is the second important fact that has long been ignored by Chinese aluminum industry companies.
The impact of the trade war
In 2017, China imported about 820,000 tons of aluminum scrap from the United States, accounting for 50% of China’s total aluminum scrap imports, accounting for 52% of total US exports.
Obviously, the Sino-US trade war will not pose a threat to the development of China’s recycled aluminum industry. As long as China’s resource efficiency is increased by 2%, it will be enough to replace the quantity imported from the United States. Therefore, the current outstanding problem in China’s aluminum industry is resource efficiency, and the core is the issue of technological innovation to enhance competitiveness.
Challenges to improve resource efficiency
Minimize the recycling of scrap aluminum and aluminum-containing scrap for recycling.
Automated mechanized pretreatment classification technology, advanced crushing and separation technology, and made it widely available.
Advanced process control technology that optimizes the processing of elements and residues that are not suitable for reuse in recycled aluminum.
Expand the number of available aluminum alloys, adapt to more aluminum scraps and directly produce them into products, and perform well in high quality and high added value.
Improve resource efficiency to achieve regenerative recycling, such as the use of hot extrusion technology to separate contaminated or mixed with the casting alloy, that is, mechanical separation using the difference between forged and cast aluminum alloy solidus temperature. Since the cast alloy has a higher alloying element content and the solidus temperature is lower than that of the wrought alloy, the mixture of the forged and foundry waste is heated to a temperature lower than the eutectic temperature, and then the forged alloy is separated by centrifugal force. The alloy element concentration is measured by a combination of techniques such as X-ray fluorescence (XRF), laser induced breakdown spectroscopy (LIBS), and X-ray transmission (XRT), and the wrought alloys having different compositions are separately separated and then melted.
Improve resource efficiency and optimize process technology to further reduce energy consumption and melt loss, reduce emissions, extend furnace life and improve alloy quality. For example, by improving the melting technique to eliminate the residual elements Fe, Sn, Mn and Cu, etc., these elements are detrimental to mechanical properties, and removal requires the addition of certain alloying elements to neutralize, which requires more research to improve the knowledge of recycling techniques. The manufacturing process of the new alloy also needs to be optimized accordingly. Research is needed on the basis of the process to better understand the physical phenomena that occur during melting, solidification and recycling, thus creating a knowledge base for aluminum producers to better control their processes, including the following:
- Continue to develop methods for recovering aluminum scrap from as many products as possible.
- Strategies should be adopted for the most cost-effective remelting process, including the promotion of the separation of unwanted elements such as Fe, Ni technology.
- Alternative products, such as Al-Fe deoxidizers, should be developed to take advantage of recycled aluminum parts that cannot be cost-effectively used to produce new aluminum alloys.
- New aluminum alloys designed for direct application to recycled aluminum should be carefully considered and studied.
- A study should be conducted to explore the potential for increasing the amount of alloys that can be used for direct recovery. The study should more accurately identify the current and future sources of recycled metal content and the expected composition range.
Improve resource efficiency and realize the harmlessness and resource utilization of slag. Aluminum slag, aluminum ash, salt and compound alumina can be completely recovered by using advanced technology and recycled as non-toxic materials. At present, aluminum slag has been banned in the United States, Canada and Europe. The treatment of aluminum slag has a considerable economic effect and directly affects the profitability of the enterprise. The measures that should be taken currently include the following:
- Optimize the process to prevent oxidation of the aluminum slag.
—— Shorten the transportation distance of aluminum slag, quickly close the cooling and prevent oxidation loss.
- Treat aluminum slag under the protection of salt.
—— Establish a salt residue disposal system to stabilize the recovery rate of aluminum above 98%, salt can be recycled indefinitely, and green inert alumina can enter the downstream industry.
In short, there is considerable room for improvement in the resource efficiency of aluminum recycling in China. The focus of innovation is to increase the value of aluminum scrap, reduce degradation and dilution, expand the ability to melt different types of waste, and establish and improve the slag treatment system. As long as these measures are in place, the losses recovered are immeasurable, which is of great significance for saving resources and protecting the ecological environment, improving the competitiveness of aluminum industry enterprises, and promoting the healthy development of China’s recycled aluminum industry.