A method and device for resource utilization of high-ammonia nitrogen wastewater from wet-process rare earth smelting

Abstract

The invention discloses a wet-process rare earth smelting high ammonia-nitrogen wastewater resource utilization method which comprises the following steps: step one, pretreating high ammonia-nitrogen containing wastewater through alkalization, sedimentation and filtration; step two, introducing the pretreated wastewater into a wastewater preheater, and preheating; step three, introducing the preheated wastewater into an ammonia distillation tower, carrying out ammonia distillation, and forming strong aqua ammonia with the concentration of 13%-20%; and when the ammonia nitrogen concentration of tower bottom wastewater is not more than 100 ppm, discharging out of the ammonia distillation tower, and introducing into a barrel of the wastewater preheater to be used as a thermal fluid; and step four, carrying out deep treatment on the wastewater after heat exchange, and when the ammonia nitrogen concentration is not more than 10 ppm, discharging the wastewater outwards. The embodiment of the invention also discloses a wet-process rare earth smelting high ammonia-nitrogen wastewater resource utilization device. With adopting of the method and the device, the ammonia nitrogen wastewater with different concentrations is subjected to two-stage treatment of the ammonia distillation method and the depth treatment method, the resource utilization rate of the high ammonia-nitrogen wastewater reaches more than 95%, the processing energy consumption is reduced, the equipment scaling time is prolonged, and thermal pollutions of wastewater discharging are decreased.

Description

Technical field [0001] The invention relates to the field of wastewater treatment, in particular to a resource utilization method of wet rare earth smelting high ammonia nitrogen wastewater, and correspondingly, also relates to a device for implementing the resource utilization method of wet rare earth smelting high ammonia nitrogen wastewater. Background technique [0002] Rare earth materials play an indispensable and key role in modern emerging green energy technologies, high-tech and national defense systems, such as electric vehicles, wind turbines, lighting and displays, computer hard drives, mobile communications, missile guidance, and smart bombs. These technologies are called "rare-earth dependent technologies" internationally, and no other materials can replace them. Therefore, rare-earth materials have become indispensable strategic materials for realizing technologies and transforming traditional industries. The rare earth industry is developing rapidly and the scale ...

AI Technical Summary

Problems solved by technology

At present, most rare earth smelting enterprises in my country are facing serious environmental pressure due to the limitation of wastewater treatment technology and treatment cost. Only some enterprises only use simple evaporation, concentration and crystallization process to recover ammonium chloride for high-concentration ammonia-nitrogen wastewater. Short, high energy consumption, high operating costs, and because of incomplete pretreatment, the recovered ammonium chloride product has low purity, poor economic benefits, and enterprises are not motivated to operate; on the other hand, for the medium For low-concentration ammonia-nitrogen wastewater, most enterprises simply add lime to adjust the pH and then discharge it directly, causing great pollution to the ecological environment. At present, there are no relevant reports that comprehensively consider the recycling of rare earth hydrometallurgy wastewater resources and zero-discharge wastewater

[0004] In order to solve the wastewater containing high ammonia nitrogen produced by rare earth smelting, and recycle the ammonia nitrogen in the wastewater, the existing technology, such as Chinese patent CN 102030438 B, discloses a treatment method for ammonia nitrogen wastewater, which uses stripping method and resin adsorption method to remove ammonia nitrogen in wastewater , although the deamination effect is better than the traditional simple stripping method, but this method requires frequent elution of the resin due to the use of resin to absorb ammonia, the process is complicated and the cost is high

[0005] Chinese patent CN 101863597 B discloses a method for treating high ammonia nitrogen sewage, which mainly includes the following steps: (1) storing and homogenizing ammonia nitrogen sewage, (2) using the prepared activated sludge to biodegrade COD, BOD and NH in the sewage 3 -N pollutants, (3) Slurry-water separation of sewage, (4) Membrane separation treatment of sewage, sludge-water separation and membrane separation treatment of sewage, good degradation effect on ammonia nitrogen, COD, BOD, but membrane regeneration cost Large, poor economic efficiency

[0006] Due to the high ammonia nitrogen wastewater produced by the rare earth smelting industry, which has high chloride radicals, high ammonia content, high salinity, and strong acidity, but has the characteristics of high resource recovery value, rare earth smelting enterprises are faced with the problem of large investment and high operating costs, which has become serious. restricted the development of the industry

Traditional ammonia nitrogen wastewater treatment methods such as air stripping method, ammonia distillation method, rectification method, biological nitrification-denitrification method, etc., these methods have secondary pollution, high energy consumption, limited processing capacity, and easy crystallization and scaling inside the equipment affect operation and other problems, and it is difficult to recover ammonia resources

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