[China Aluminum Industry Network] With the development of science and technology and the continuous improvement of human living standards, people's demand for aluminum alloy products has increased year by year, and the application of aluminum alloy materials has also been expanding; however, due to the blindness of aluminum resource exploitation, China Aluminum mineral resources have become scarce. Therefore, how to effectively utilize aluminum scrap resources for comprehensive utilization has aroused great attention in the aluminum processing industry. Compared with the production of primary aluminum, the recycling of scrap aluminum can save a lot of energy such as water and electricity, reduce production costs, and reduce pollution to the environment. Therefore, recycling of scrap aluminum is an important manifestation of the development of a green recycling economy. At present, China’s waste aluminum recycling output has exceeded 5 million tons, but it only accounts for about 20% of the total aluminum production. With reference to the development goals set in the “Long-Term Science and Technology Development Plan for the Non-ferrous Metal Industry (2006-2020)â€, by 2020, In the year, the proportion of recycled aluminum production in China's total aluminum production increased to 40%. If this goal can be achieved, it can save hundreds of billions of kilowatt hours of electricity consumption, reduce tens of millions of tons of wastewater, and discharge hundreds of millions of tons of waste residue each year. It can be seen that promoting the development of the waste aluminum recycling industry is of special significance for the development of recycling economy, resource conservation and energy, and improvement of the natural environment. First, the high degree of mixed materials has become a key technical problem for the development of recycled aluminum Western developed countries attach great importance to the development of the recycling industry of aluminum scrap, and most countries’ production of recycled aluminum accounts for more than 50% of the total aluminum processing output. Of these, 50.6% were in Germany, 52.4% in the United States, 75.6% in Italy, and 99.5% in Japan. Obviously, recycled aluminum has become an inevitable trend for the sustainable development of the world aluminum industry. Compared with the primary aluminum production process, the aluminum scrap regeneration is characterized by the fact that the raw materials are recycled aluminum scrap parts, production scraps, construction aluminum, packaging aluminum, scrap aluminum cables and so on. As a result, the problem of high levels of mixing of waste aluminum recycled materials is highlighted. At present, there are two main sources of raw materials for domestic recycled aluminum producers. One is raw materials imported from abroad, and the other is aluminum alloy scraps recovered from the circulation area. These raw materials are often doped with other metal and non-metallic inclusions. 1 The waste aluminum raw materials come from different fields of use and contain more complex aluminum alloy series and grades. For example, the cast aluminum is mainly composed of high silicon (Si) aluminum alloys, and the aluminum profiles for building profiles or structures are mostly made of magnesium (Mg). Most of the 6XXX series alloys with Si as the main alloying elements and aluminum materials for decoration use aluminum (Al)-Mg alloys, wire and cable, and packaging materials, mostly pure aluminum, which are often mixed in the collection process; 2 A variety of aluminum raw material recycling channels, in the recycling process will be subject to different levels of pollution, but also mixed with many non-aluminum materials; 3 for product packaging and other functional needs, many aluminum and alloy products are coated with organic coatings Or lacquer, etc.; This mixed material with various inclusions cannot be processed directly by casting or deformation. The main reason is that if these raw materials are directly melted and cast, a large amount of these aluminum elements will be mixed in and organic or inorganic inclusions will be introduced. Various physical and chemical reactions will occur, which will not only cause a large amount of toxic gases during the smelting process. , And will be involved in the casting and solidification process in the matrix, resulting in porosity, porosity and other defects; also will form a large number of solid inclusions in the matrix, resulting in the material's microstructure and performance can not achieve the desired goal, As a result, most of the recycled aluminum products can only be limited to primary products such as ingots. The ability to improve the deep processing of scrap aluminum recycling and the production of high value-added products is a common goal pursued by all countries in the world. To obtain high-quality recycled aluminum products, the pretreatment of waste aluminum raw materials becomes a very critical link in the production of recycled aluminum, including the collection, storage, classification of raw materials, the treatment of surface paint films, and the removal of non-aluminum elements. Second, waste aluminum recycling and management system needs to be further standardized The classification and recovery of raw materials is the last link to achieve pure purification of raw materials. The basic requirement of a recycled aluminum production enterprise is to obtain relatively pure scrap aluminum raw materials, reduce the incorporation of large amounts of non-aluminum elements, and organic or inorganic inclusions. This requires the primary classification of waste aluminum at the time of raw material recovery, thereby realizing the division and stacking of different types of waste aluminum raw materials, and ultimately reducing the difficulty of the regeneration of waste aluminum. The practices of some companies in our country are worth learning from. For example, China's larger importer of aluminum scrap, Shanghai Xinge Non-Ferrous Metals Co., Ltd., has a higher degree of automation in raw material processing, and can realize the storage of all incoming raw materials according to the type of aluminum alloy. And established a cost management system. This effective material management model ensures product quality. Therefore, the most urgent task for China’s renewable aluminum industry is to establish a reasonable and complete recycling system for used aluminum raw materials, summarized as follows: 1 productive waste aluminum raw materials. It is mainly a kind of determined waste products or defective products produced in the production process of products, process wastes such as pouring risers, etc. These materials have relatively uniform chemical compositions and are high quality recycled aluminum raw materials, which should be recycled separately and provided to the corresponding Professional manufacturer. 2 Classify and collect waste aluminum raw materials in different fields of use. Most of the waste aluminum materials used in different fields have obvious differences in chemical composition and performance. For example, aluminum cans mainly consist of 3003 or 3104 alloys, aluminum for cable conductors is basically pure aluminum, and building profiles are mainly 6063 or 6061. Such as the classification and collection of these raw materials and storage, respectively, applied to the same type of aluminum alloy products, will greatly reduce the difficulty of raw material processing, improve the utilization of the alloy. 3 The classification of the mosaic pieces. In the aluminum parts of used machinery or equipment, there are some aluminum and steel, copper, plastic, etc., which become parts by inlaid combination. These parts are tightly combined by aluminum and other non-aluminum metals, and they pass through conventional magnetic separation and winnowing. Other measures are not able to achieve non-aluminum alloy separation, and because the relative proportion of non-aluminum alloy is relatively large, so this type of waste aluminum raw materials should be collected separately, centralized treatment. Developed countries have already established a complete waste aluminum collection and management system. They have improved the efficiency of classified collection of waste aluminum raw materials through national administrative legislation, regulation of industry practices, and logistics management systems for manufacturing and distribution industries. For example, in the United States, more than 500,000 tons of can-making cans are made from cane factory scraps and old cans. In addition, through the development of continuous smelting and processing technologies and other innovative technologies to upgrade the low-grade waste aluminum, the raw material purity of the waste aluminum recycling production system is improved. However, subject to various objective conditions, China has not formed a scientific recycling system. The low level of resource enrichment has affected the utilization of waste aluminum raw materials; many waste material recycling and processing companies are still adopting very primitive methods, and have no sense of innovation or lack of financial capacity to introduce or adopt new technologies, new processes, and new equipment. , hindered the development of waste aluminum recycling. Therefore, it is imperative to establish a complete system for recycling, transporting, processing, and using waste products. Third, pay attention to the removal of scrap aluminum raw materials surface of the process technology In the collection process of waste aluminum raw materials, the quality requirements are relatively low, and the storage conditions of the recycling companies are limited. This causes a large amount of sludge, dirt, etc. to adhere to the surface of the waste aluminum raw materials, and the surface of some products is also seriously rusted. Corrosion is often the main source of large amounts of oxide inclusions in the melting of raw materials, and will greatly reduce the quality of recycled aluminum products. Aluminum alloy products are often sprayed with various coatings or coatings on their surfaces for the purposes of product identification, surface protection, and aesthetics. Various organic or inorganic materials, etc. Once these materials are brought into the melting process of the raw materials, the melt will cause serious inhalation. During the solidification process, defects such as pores, porosity, etc. will easily occur; and the incorporation of inorganic substances will generate a certain amount of Non-metallic inclusions reduce the performance of the material [. Therefore, in order to improve the smelting quality of waste aluminum raw materials, it is better to remove the paint film, oil stain, etc. on the surface of the waste aluminum raw materials before the raw materials are put into the furnace. The waste oil on the aluminum surface can be removed with detergents, etc. The difficulty lies in the removal of the surface paint film. The surface paint layer is a chemical paint containing organic hydrocarbons as the binder and titanium dioxide (TiO2) as the main component. It contains TiO2, Fe, Ti, Al2O3, and SiO3. As inorganic materials, they are tightly bound to the aluminum alloy base material and are difficult to remove by cleaning or other methods. At present, the dry film, wet method, and mechanical polishing are used to remove the surface film at home and abroad. Rotary kiln method The rotary kiln method is a commonly used surface treatment process for dry paint film. The waste aluminum raw material is loaded into the rotary kiln. The rotary kiln is rotated at a certain speed and heated, and the surface paint layer is gradually charred at a higher temperature; Under the action of impact and friction, the carbides fall off from the surface of the aluminum alloy. The advantage is that the thermal efficiency is high, but it may cause the burning of aluminum. 2. Wet processing Wet treatment is to immerse waste aluminum raw materials in chemical solvents. Using the principle of “similar dissolution†of organic substances, the organic binder in the surface paint film will dissolve in organic solvents, causing the paint film to fall off from the surface of the aluminum alloy substrate. The advantage is that it does not damage the aluminum matrix, but it will produce secondary pollution. For the purpose of avoiding secondary pollution, some scholars have studied the ice jet method and achieved good results. 3. Mechanical grinding Mechanical grinding is a relatively primitive process method. Sanding is used to remove the lacquer layer on the surface of the can, but the grinding process does not completely remove the lacquer layer, and the grinding process also causes loss of the inner layer of aluminum alloy. It can be seen that the goal of technological research and technological innovation to remove organic and inorganic substances such as paint films on the surface of waste aluminum is to prevent new pollution, and at the same time, not to damage the inner aluminum alloy and increase the yield of aluminum alloy. Fourth, the sorting and treatment of waste aluminum raw materials is the key to improve the quality of scrap aluminum regeneration The delivery of waste aluminum raw materials is mainly to reduce the non-aluminum metal element mixing and non-metallic impurity removal to a greater extent, through the use of different types of raw material sorting process and the corresponding high degree of automation, high sorting efficiency of the machinery Equipment, to achieve non-aluminum metal and non-metallic inclusions affecting the quality of recycled aluminum, etc. Effectively separate and remove from the raw materials, better to achieve scrap aluminum raw materials can be divided according to the main alloying elements of aluminum scrap raw materials, such as the raw material in the aluminum-magnesium alloy Aluminum alloys, aluminum alloys, aluminum-zinc alloys, aluminum-silicon alloys, and other major aluminum alloys are separated and stored and supplied separately, which can greatly increase the efficiency of recycled aluminum production. Western developed countries, such as the United States, Japan, Germany, and Australia, attach great importance to the technical research and application of aluminum waste pretreatment. At present, a relatively complete process technology, equipment manufacturing and intelligent control of aluminum scrap pretreatment have been formed. System [8]. The waste aluminum pretreatment technology that has been put into use now mainly includes the following six kinds: Wind-selection The winnowing method is mainly used for separating light, powdery and other materials from waste aluminum materials, such as waste paper, waste plastics and dust. The process principle is as follows: using blowers, air compressors, etc. to generate a certain pressure of the wind, to blow away some impurities such as waste rubber, waste plastics, waste wood, waste paper, etc. in the waste aluminum raw materials, and remove the waste aluminum raw materials. Non-aluminum inclusions. This method can efficiently separate most of the light waste, but it must be equipped with appropriate environmental protection facilities to avoid the environmental hazards of the process implementation. 2. Electromagnetic separation Electromagnetic separation is a process mainly used for separating magnetic materials such as scrap iron and steel in scrap aluminum, and is widely used abroad. The equipment is relatively simple, the magnetic source comes from an electromagnet or a permanent magnet, and most of them use the cross method. The waste aluminium raw material is placed on the conveyor belt in the transverse movement. After entering the magnetic field, the waste steel is taken up and taken away by the longitudinal belt. After a certain distance from the magnetic field, the waste steel material loses its magnetic force and falls into a specific collection box, thereby realizing the scrap steel. The purpose of separating material from scrap aluminum raw materials. The magnetic separation method has a simple process and low investment, but its process requirements are relatively high, and the volume of the waste aluminum material should not be too large. The combination of aluminum and steel components in the form of mechanical joints requires manual dismantling and sorting, and direct use of electromagnetic methods is difficult to separate. For the inclusion of other non-aluminum elements or difficult-to-separate assembly, the main purpose of the present is to heat the aluminum scrap raw material in a dedicated melting furnace, strictly control the melting temperature and standing time, and use the difference in melting point and the specific gravity to treat the scrap steel. And other materials are filtered out. 3. Flotation separation The principle of flotation separation is the use of physical properties such as density and solubility to exclude non-aluminum materials, mainly wet and dry processes. In the wet flotation method, liquid substances such as water or organic solvents are used to float a substance having a low density in the non-dissolving material on the surface of the water, and a substance having a density higher than that of the water sinks in the water. This method can separate lightweight materials with a density lower than that of water and is simple and easy to implement. However, the investment is very large. At the same time, due to the shape of the waste, the main equipment used is a spiral propeller. Dry flotation uses solids such as dry sand as the medium, using high-pressure air to produce convection, and take away the light materials; but the appropriate fluidized media and automatic completion of separation are still in the research stage. 4. Parabolic sorting The principle of the parabolic sorting method is to use different process methods such as high-speed conveyor belts to throw mixed wastes, use different density of metals, and different quality, and throw different materials to different landing points so as to achieve Different material separation effects. According to this principle, the corresponding equipment has been designed and manufactured and has been put into use abroad. However, the equipment has a complicated structure and is expensive, which limits the application. 5. Eddy current separation The principle of eddy current separation technology and parabolic separation is very similar. The big difference between the two is that the eddy current separation is in the alternating magnetic field. The conductivity and density of different metals in waste aluminum raw materials are different, and the magnetic field is different. Metals produce different repulsive forces, and the particles of these materials are thrown to different distances. The raw material separation ability of the method is strong, and the aluminum scrap can be separated from non-metals such as plastics, glass, rubber, etc. However, the existing problems are similar to the parabolic sorting process, which is mainly reflected in the expensive equipment and the equipment For longer magnets, the raw materials must be iron-removed in advance to avoid the eddy current heating effect of ferromagnetic materials and damage the equipment. 6. Electrostatic method The electrostatic method utilizes the difference in conductivity between different materials in the waste aluminum raw materials to place the waste aluminum raw materials into the electrostatic separation equipment. The difference in the stress state between the different materials causes different trajectories when the materials fall, and thus the aluminum and other materials Classified and collected to achieve the goal of pure purification treatment of waste aluminum raw materials. The above process methods mainly use the differences in physical properties between different substances in the aluminum waste materials to achieve the separation of materials, and can effectively separate aluminum from other non-aluminum impurities, and have also been widely used in the actual production process. However, aluminum alloy materials with different physical properties with different chemical compositions cannot exert their separation effect. Aluminum alloys of different qualities are still mixed together, causing many high-quality aluminum alloys to be mixed with common aluminum alloys for low-grade production. Recycled aluminum products [9] cause a great waste of resources. In order to solve this problem, some foreign institutions have researched and developed many new process methods in recent years in an attempt to solve the above problems. 1 Based on the color contrast material sorting method, the principle is to chemically etch the aluminum scrap raw material, and the colors of the different components of the alloy after corrosion are different, so that the color of the raw material particles can be graphically analyzed by the computer. Different materials are distinguished. HVS uses this technology to separate 99% of magnesium from aluminum. However, during the implementation of the process, the smoothness of the raw material surface is required to be very high, and the temperature, surface roughness, and corrosion time greatly affect the process. Therefore, relatively strict pretreatment of the waste aluminum material is required; in addition, the implementation of the method is also required. The need for special light source systems and powerful data processing capabilities makes the equipment expensive. 2 X-ray fluorescence analysis (XRF), optical emission spectroscopy (OES), and laser-induced breakdown spectroscopy (LIBS) are all used to introduce component analysis into the field of material sorting, making the distinction between materials more accurate [11]. The principle of component analysis varies. However, no matter what kind of technology, its equipment is complex and expensive, and it is required that the surface of waste aluminum materials must be clean. V. Suggestions and Prospects At present, in the research of aluminum scrap recycling, the separation process of scrap aluminum raw materials has attracted the attention of various manufacturers. Many companies already have equipment conditions for the pretreatment of waste aluminum raw materials such as magnetic separation, gravity separation, and wind separation. The starting point for the development of waste aluminum recycling industry is relatively low, and there is little support for the pretreatment of waste aluminum raw materials in terms of technology and capital, so the sorting of waste aluminum raw materials has not been widely implemented, especially for many SMEs in China. Due to the late start, insufficient attention was paid to the separation and separation technology of aluminum scrap, and some enterprises still use simple manual sorting, that is, using simple tools such as magnets, steel files, hammers, pliers, and reeling tools, which not only has high labor intensity but also has high costs. The quality uniformity is poor, and the sorting efficiency of waste aluminum raw materials is very low, unable to form the production capacity of high-performance products of recycled aluminum, which seriously restricts the further development of China's recycled aluminum industry. In order to further improve the production capacity and product quality of the waste aluminum recycling industry, the classified collection, classification, processing and processing technologies of waste aluminum raw materials require strong support from high technology and should be closely integrated with the mechanical design, chemical technology, physical technology, and new material technologies. The formation of a strong industrial complementarity industrial chain. In fact, China’s aluminum recycling industry has achieved certain results in the use of magnetic separation, gravity separation, and winnowing processes to sort waste aluminum raw materials. It is possible to separate the non-aluminum materials such as iron, copper, and zinc from waste aluminum raw materials. Although there is still a certain gap, with the increasing emphasis placed on the pretreatment of scrap aluminum raw materials, the level of these physical separation processes will gradually increase, and will play an increasingly important role in the pretreatment of waste aluminum raw materials. However, no progress has been made in the sorting of aluminum alloy raw materials in waste aluminum materials. In particular, technologies and equipment for foreign materials such as XRF and LIBS that have been classified by component scanning have not been applied in China due to their high equipment and poor process adaptability. Therefore, it is necessary to combine the characteristics of China's waste aluminum recycling industry, to carry out technological research and development work with simple process, equipment investment, and aluminum alloy raw material classification function or raw material processing, which will be very practical for the improvement of waste aluminum regeneration quality. For example, Yuan Xiaodong, a reclaimed aluminum material researcher, designed and prototyped a comprehensive pretreatment equipment for recycled aluminum scrap, using a two-step gasification melting technology to vaporize the recycled aluminum raw materials under a reducing atmosphere and a certain temperature. Recyclable clean aluminum metal, in which flammable, flammable organic matter is converted into flammable gas for fuel reuse. At the same time, further pyrolysis of flammable and poisonous gases can continue, resulting in the formation of dioxins, reducing the Environmental hazards. How to effectively realize fast, accurate, low-cost, continuous and efficient separation of non-aluminum materials from scrap aluminum raw materials, while achieving as much as possible a detailed classification of different aluminum alloy materials, reducing the difficulty of composition adjustment in the smelting process, and improving aluminum scrap The process performance of the regeneration process, obtaining high-quality recycled aluminum products that meet the requirements of chemical composition, and having a good organizational morphology, and achieving green recycling economy development will be the focus of attention in the future. MONBAND is the first company to register and produce Water Soluble Fertilizer in China. SOP Fertilizer,Potassium Sulphate,Water Soluble SOP,Straight Fertilizer,100% Water Soluble Potassium Sulphate Hebei Monband Water Soluble Fertilizer Co., Ltd. , https://www.wsfertilizer.com
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