Arsenic and antimony are heavy metal elements having high toxicity, and their presence in the environment will have a serious impact on human health and ecological safety. There are drinking water safety problems caused by arsenic pollution of natural groundwater around the world. And in terms of antimony, it is mainly due to drinking water source or water body antimony pollution considered to be caused by antimony ore mining and antimony-containing wastewater discharge. In Chinese “drinking water sanitary standard” (GB5749—2006), stricter regulations are made on the arsenic concentration limit, requiring that the maximum concentration of arsenic in drinking water must be lower than 10 μg/L and the concentration limit of antimony is 5 μg/L.
In recent ten years, a lot of research and technological developments on removal of arsenic and antimony have been carried out both at home and abroad. Removal methods such as adsorption, flocculation-precipitation-filtration, flocculation-direct filtration, electrodialysis, ion exchange, membrane separation and the like have been researched systematically. Adsorption method is still one of best methods for removing arsenic and antimony in water. In terms of adsorbing materials for removing arsenic and antimony, adsorbents reported at home and abroad include materials such as active alumina, red mud, modified active carbon, hydroxy ferric oxide, GFH®, READ-As®, manganese sand, hydrated manganese oxide, ferric oxide-alumina composite nano material, iron-manganese composite oxide/diatomite and the like. For example, the ferric oxide-alumina composite nano material (Patent application No.: CN200710118307.1) invented by CAI Yaqi et al. has a fine particle size and a large specific surface area, thereby exhibiting a strong capability to remove pollutants such as arsenic in water. In a design process of an adsorbent, there is an unavoidable contradiction that the smaller the particle size is, the stronger adsorption performance to the waste is, but requirements for solid-liquid separation are stricter; on the contrary, if the particle size is increased and the particles are used as fillings for adsorbent bed, the adsorption performance decreases. The development of a technical method for effectively improving the solid-liquid separation may be the key to solve the above contradiction.
Materials are magnetized to form magnetic functional adsorbing materials, which are widely researched internationally, but there is still no case of pilot scale or engineering application scale up to now. The reason is that there is still no efficient, economical and capable of being industrialized magnetic separation device. In view of this problem, Jiangsu Jack-Zhongke Superconducting Technologies Co., Ltd. carried out system development, and obtained important breakthroughs in superconducting separation of magnetic materials, forming a series of key technologies (such as CN201110053441, CN201310583350, CN201310516009). On the basis of early research and development, the inventors of the present invention propose that a weakly magnetic material, iron-based gel having a strong adsorption capacity is supported on a ferrite material having a weak adsorption capacity but strong magnetism by means of reacting in situ, thereby a material having both a strong adsorption capacity and an excellent magnetic separation characteristic is obtained. Solid-liquid separation is completed by a continuous superconducting magnetic separation system after the material adsorbs arsenic and antimony. CN103736586A discloses a continuous superconducting magnetic separation system and an application process thereof. The continuous superconducting magnetic separation system comprises a vertical cylindrical superconducting magnet, high gradient dielectric networks, a high-medium network supporting system positioned at the lower end portion of the cylinder in the superconducting magnet, a high-gradient medium rotating disc provided with a bayonet, a high-gradient medium field outside transmission system, and a press system for realizing the entry of the high-gradient medium to the magnetic field and the exit of the high-gradient medium from the magnetic field. After a material for separation enters the superconducting magnetic field, magnetic particles are adsorbed in the high-gradient medium network, and nonmagnetic particles are collected at the lower end of the superconducting magnet. The high-gradient medium networks are stationary in the superconducting magnet through a magnetic separation zone support system, and enter or exit from the magnetic field through the press system one by one. The high-gradient medium networks adsorbed with the magnetic particles exit from the magnetic field, sequentially enter a cleaning zone and a magnetic field outside transmission zone through the high-gradient medium rotating disc, and afresh enter the magnetic separation zone through the press system over the superconducting magnet, so as to achieve a continuous operation.