New progress in superconducting magnetic separation water treatment system

New progress in superconducting magnetic separation water treatment system

Recently, the "Superconducting Magnetic Separation Water Treatment System" developed by the Institute of Physics and Chemistry, Institute of Physics and Chemistry, Chinese Academy of Sciences, has made new progress. The superconducting magnetic separation water treatment system using a superconducting magnet as the core has been successfully operated. The magnetic separation water treatment equipment breakthrough from scratch, the system can be automated, stable operation for a long time. Through debugging and testing, the water treatment system has been able to carry out a sewage treatment experiment efficiently and quickly, and a comparative test shows that the sewage treatment effect is significant.

At present, industrial wastewater treatment methods mainly include chemical methods and biochemical methods. However, practical chemical and biochemical methods have problems of large investment, high operating cost, long reaction time, large area, low efficiency, and high energy consumption. For small-scale paper mill wastewater treatment, these problems are even more prominent. Manufacturers have invested too much in setting up sewage treatment facilities, and most of them have taken direct discharges, causing harm to the environment.

The work of the Institute of Physics and Chemistry of the Chinese Academy of Sciences overcomes the above problems and made innovative progress in magnetic seed material and superconducting magnet cooling technology. An organic film with active groups is grown on the surface of Fe3O4 magnetic particles by plasma organic coating technology. This layer of nanometer-thick film can effectively capture organic and inorganic ions in the sewage, instead of organic flocculants, and due to the organic film. It has a strong binding force with Fe3O4, making this new type of composite "magnetic seed" material reusable and has obvious advantages over simple Fe3O4 magnetic seed material.

The use of this "magnetic seed" material in paper mill wastewater treatment experiments shows that the COD value of the magnetic separation water treatment wastewater from the initial 1780mg/L to 147mg/L, the removal rate of more than 90%%, the purification effect is good. Another technological innovation is the use of a chiller to directly cool superconducting magnets, thereby freeing them from the use of expensive liquid helium. This will allow superconducting magnetic separation wastewater treatment systems to be easily used in areas where liquid helium is not available, particularly suitable Small and scattered SMEs. It is a technology with potential application value in the future.

It is understood that the magnetic separation technology was first applied to beneficiation and china clay industry. Before 1960, the Soviet Union first used magnetic coagulation method to treat steel plant dust removal wastewater. However, the magnetic field strength of permanent magnets or electromagnets is limited, and the treatment effect for weak magnetic particles is not ideal. In recent years, researchers at home and abroad have tried to separate magnetic impurities using superconducting magnetic separation technology. Superconducting magnetic separation method has lower investment, less land occupation, and less power consumption than conventional chemical methods, biological methods, and common electromagnetism and magnetic separation. Small advantages. In terms of land occupation, superconducting magnets with a field strength of 3 to 5 Tesla, plus corresponding refrigeration equipment, occupy an area of ​​no more than 20 m2. In terms of energy consumption, since superconducting materials have no resistance, superconducting magnets do not consume much electric energy, and only maintain a low-temperature refrigerator power consumption. The power consumption per day does not exceed 100 kW·h. In terms of cost, 3 to 5 Tesla's superconducting magnets are about 1.5 million yuan, and the investment is less than 2 million yuan for a one-kiloton-scale device. Therefore, superconducting magnetic separation technology is a promising technology for wastewater treatment. The research results show that the magnetic separation technology of superconducting magnetic separation is effective for the magnetic separation and purification of wastewater from steel plants rich in iron oxide impurities. However, this technology can only separate magnetic contaminants from water. For petroleum production water, papermaking, chemicals, pharmaceuticals, food, etc. Industrial waste water and urban domestic waste water, because these poisonous and harmful substances in waste water are mostly organic, they are not magnetic, and they cannot be effectively separated by magnetic separation.

Li Laifeng, a researcher at the Institute of Physics and Chemistry, Chinese Academy of Sciences, proposed a plasma-coated modified magnetic species for superconducting magnetic separation technology that can effectively solve the above problems. First, an external coil and a plasma organic polymerization device powered by a radio frequency power supply are designed. The surface of the magnetic seed material is subjected to surface plasma organic polymerization, and the modified magnetic species is formed into various desired surface functional groups. These active groups can be flocculated with non-magnetic and harmful substances in the sewage, and then pass through the strong magnetic field of the superconducting magnet to separate the pollutants from the wastewater and achieve the standard discharge of industrial wastewater. Researcher Li Laifeng and his research team conducted a preliminary discussion on the mechanism of flocculation. It is believed that the magnetic species weakened the double layer on the surface of pollutants as an electrolyte, and the pollutants formed a floc through electrostatic adsorption, bridging, and trapping. After adjusting the type of functional groups on the magnetic seed surface, the technology can be adapted to different types of sewage treatment. The used magnetic species can also be reused by desorption.

In superconducting magnetic separation wastewater treatment technology, the development of highly efficient magnetic seeds is the key. In order to achieve a good sewage treatment effect, it is required that the magnetic seed material have: 1 the highest possible volume susceptibility to obtain a better magnetic response; 2 the lowest possible coercive force to reduce the agglomeration when there is no external magnetic field; 3 appropriate The particle size, small particle size, large surface area, high activity, can be better combined with the pollutants in the sewage, but the particle size is too small will affect the magnetic susceptibility, while the use of large losses, is not conducive to recovery and repetition Use; 4 chemically stable, not easy to be corroded; 5 surface modified with a suitable method, so that magnetic seeds can be better with the combination of pollutants, and through the use of different ways to surface modification to deal with different types of sewage.

Low-temperature superconducting magnetic separation water treatment is a cutting-edge new technology and has important application prospects. It is considered as another promising new industrial application after the application of superconducting magnets in medical nuclear magnetic spectrometers and mineral magnetic impurities separation fields. . With the rapid economic development, environmental pollution and energy shortages have increasingly become the focus of the country's issues. At present, China's superconducting magnetic separation technology continues to make breakthroughs, and its application in water treatment is expected to become a symptomatic prescription for resolving water pollution problems, which is of great significance for the development of the national economy.

A study on the application technology of superconducting magnets shows that superconducting high-gradient magnetic separation technology can be used for purification and separation of wastewater from papermaking, chemical and pharmaceutical industries. Compared with traditional superconducting magnetic separation technology, which can only separate magnetic impurities in minerals, coal, and kaolin, this technology preliminarily adds modified magnetic seed particle materials to separate non-magnetic organic and inorganic pollutants from industrial wastewater and achieve industrial Sewage discharge standards.

The Institute of Physical and Chemical Materials for Low-temperature Materials and Applied Superconductivity Research Center began research on low-temperature superconductivity technology in 2005. After years of accumulation, it has done a lot of related basic research and exploration, especially for the research and development of magnetic seeds, successfully developed for different pollutants. Different applicable magnetic seeds. The equipment is optimized for design, layout is reasonable, the area is less than 6m2, and it can be designed as a vehicle-mounted mobile type, stable water flow status, continuous system operation, simple operation, becoming the first superconducting magnetic separation water treatment system in China, creating a domestic A precedent for the application of superconducting magnetic separation technology in water treatment.

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