Dig up real money from used phones

◎ Intern reporter Shen Wei

Studies have shown that a used smartphone contains a variety of valuable materials, with a gold content of about 0.015%, silver content of about 0.3%, copper content of about 20%-25%, renewable materials content of about 40%-50%, in addition to platinum, aluminum, palladium and so on.

According to the website of Spain's "Abesse" newspaper recently reported, "1 ton of smartphones can extract 235 grams of gold and 1 kilogram of silver", and the mineral deposits in discarded smartphones are very rich. At present, the speed of electronic product replacement is accelerating, especially smart phones with a wide range of applications in daily life. At the same time, the number of used smartphones is increasing, and the value of this "urban mine" is being seen.

Many people do not know how to properly dispose of used smartphones, in fact, if used smartphones are not properly disposed of, on the one hand, it will cause pollution and harm to the environment, on the other hand, it will waste many of these precious recyclable resources.

Contains a variety of materials with recycling value

Studies have shown that a used smartphone contains a variety of valuable materials, with a gold content of about 0.015%, silver content of about 0.3%, copper content of about 20%-25%, renewable materials content of about 40%-50%, in addition to platinum, aluminum, palladium and so on.

Professor Du Huanzheng, director of the Institute of Ecological Civilization and Circular Economy of Tongji University, told reporters that in China, the content of a ton of waste smartphone gold can reach 280 grams and the content of silver can reach 2000,60 grams, which is equivalent to 13 times and 1 times of the original ore, respectively, which can be called an "urban mine", and the value of metal in 23000 ton of waste smartphones can reach <>,<> US dollars.

Many high-value metals can be recycled from used smartphones, at least gold, silver, copper and other high-value elements, most of which come from mobile phone circuit boards. In addition, there are a large number of chips distributed on the circuit board, and there is a non-metallic element silicon. After the crystalline silicon obtained by purification is processed, the single crystal silicon used to make semiconductor components can finally be obtained.

"The vast majority of smartphones now use lithium batteries, and there are many metal elements that can be recycled. Most lithium batteries use cobalt oxide as the positive electrode and graphite as the negative electrode, and the recovery value of cobalt elements in the battery can reach hundreds of millions of yuan per year in the country. Du Huanzheng said.

In addition, there are rare earth element lanthanum, which makes the display effect of mobile phone screens more vivid, and neodymium, a super magnetic rare earth element used on speakers and front sensors. If these rare precious metals can be fully recycled, it can also alleviate the resource pressure brought by the large-scale production of smartphones to rare precious metals.

"Waste smartphones belong to one of the waste electrical and electronic products, which also have environmental risk attributes and resource value attributes. Under the premise of reducing its environmental risk attributes, maximizing its value is the right way to complete the recycling of used smartphones. Zhang Heran, secretary-general of the Electronic Product Recycling Branch of the China Materials Recycling Association, said that at present, there are still a large number of waste smartphones in China that are not standardized and dismantled. Some valuable materials are not fully utilized because of the limitation of process technology level, not only waste resources, but also cause harm to the environment, and the standardized recycling of waste electrical appliances such as waste smartphones has a realistic necessity and urgency.

Upgrading recycling technology to mine "electronic minerals"

"The extraction of these valuable materials from used smartphones can be roughly divided into three stages, with pretreatment being the first stage." Du Huanzheng said that this stage is mainly to separate the metal and non-metal in electronic waste to achieve the initial enrichment of metal.

Zhang Heran introduced that the recycled smartphone display screen will be transported to a special LCD display disposal enterprise for special treatment after cleaning; The plastic obtained by manual disassembly of mobile phone shells and other parts can be sold directly, or mechanically crushed and entered into the recycled plastic production process to carry out plastic granulation and make wood-plastic composite products such as EPC pallets; The circuit board needs to be disassembled from the electronic components connected to it. Lithium batteries can be obtained by mechanical disassembly of plastic or metal shells, lithium battery cells, etc.

The technologies applied in the pretreatment stage include physical treatment such as dismantling, crushing and sorting, conventional pyrolysis to decompose organic matter such as plastics and rubber in waste smartphones by high-temperature heating, and microwave pyrolysis to separate non-metallic components such as plastics and rubber by microwave heating.

Recovery and refining and purification are two stages after pretreatment. Recovery is mainly to extract and enrich rare precious metals; Refining and purification is a rare precious metal with higher purity obtained from the recovered precious metal leachate.

There are many types of techniques used in the recycling phase. Such as pyrometallurgical technology, the principle is to use metallurgical furnace high temperature heating to peel off non-metallic substances, the recovery rate of metal copper, gold, silver, palladium, etc. is very high. Hydrometallurgy is the extraction of metals by chemical reactions by contacting materials with aqueous solutions or other liquids. Precious metals such as gold and silver recovered using this technology are of high grade and high recovery rate.

"Traditional recycling technology is simple and quick to operate, but the disadvantages are also obvious." Du Huanzheng said that taking pyrometallurgical technology as an example, there are many metal impurities recovered, which need to consume a lot of fuel in the refining process, and will also produce carbon dioxide, smoke, solid particles and toxic and harmful gases.

To this end, researchers are committed to developing a biometallurgical recovery technology for extracting rare precious metals through the catalytic oxidation of microorganisms, which has the advantages of simple process, strong operability, low cost and low environmental pollution.

In addition, supercritical fluid recovery of rare precious metals technology is currently in the laboratory research stage and may be used as an auxiliary recovery technology in the future. These new technologies have broad development prospects, but they are still immature and still a long way from large-scale industrial applications.

Industrialization development still needs to form norms

Zhang Heran introduced that China's waste smart phone recycling has spontaneously formed a complete industrial chain of recycling, refurbishment, disassembly, component reuse, and refining of precious metals.

Du Huanzheng believes that extracting valuable materials from waste mobile phones is gradually forming an industry, but there are still constraints such as imperfect technology and small processing scale. "At present, China's electronic waste treatment technology with independent intellectual property rights is not advanced enough, which will make us unable to fully benefit their resources when dealing with waste smartphones, and indirectly increase the cost of disposal of residual residues." We must continue to increase investment in R&D manpower and financial resources to develop more advanced and perfect processing technologies. Du Huanzheng said that at the same time, the number of large-scale enterprises and processing capacity of waste smart phone treatment and utilization are insufficient, which also limits the development of the industry, far from being able to cope with China's current severe electronic waste disposal problems.

Zhang Heran also pointed out that the current mobile phone recycling has many problems such as imperfect recycling network system, imperfect industry policy standard system, and insufficient comprehensive recycling processing capacity. "At present, there are no special regulations or management methods for the management of the waste smartphone recycling market, the market development is not standardized, and the number of formal recycling enterprises is small. There is a lack of industry standards or specifications for the recycling, information destruction, repair and reuse of components of used mobile phones, and the development of the entire industry lacks guidance. In addition, the lack of professionals in related fields also restricts the environmental harmlessness and efficient treatment and utilization of waste smartphones in China. Zhang Heran said.

Further promoting the development of the mobile phone recycling industry and making it more standardized and perfect still requires many efforts. Zhang Heran suggested that the extended responsibility system for producers should be further improved, production enterprises should be included in the construction of the recycling system, recovery rate targets should be formulated, and production enterprises should be encouraged to use existing sales and maintenance channels to build their own, jointly build or entrust professional third parties to build a recycling network system. It is also necessary to establish and improve the industry standard system, strengthen government supervision, and issue corresponding technical specifications, guidelines, industry standards or certifications for the classification, identification, sorting, information destruction, maintenance, disassembly, component reuse, material utilization, rare and precious metal extraction and other links involved in the waste smartphone recycling industry, and manage the whole process of recycling and processing of used smartphones.

"It is necessary to encourage or standardize professional waste mobile phone recycling enterprises, scientifically carry out environmentally harmless treatment and efficient resource utilization of waste smartphones, increase the research and development and industrialization of waste smartphone classification, dismantling and deep processing technology on the existing basis, and strive to improve the professional processing capacity of waste smart phones in China." Zhang Heran said. (Science and Technology Daily)