Method for treating desulfurization ash

Abstract

The invention discloses a method for treating desulfurization ash. The method comprises the following steps of: mixing the desulfurization ash generated by a dry / semidry desulphurization process and limestone powder, which serve as raw materials of a desulfurizer in a wet flue gas desulfurization process, according to a proportion; uniformly stirring the desulfurizer and pumping the desulfurizer into a slurry pond of an absorption tower; adding a catalyst into the slurry pond; introducing oxidation air into the slurry pond; introducing flue gas into the slurry pond through a flue; reacting the desulfurizer with SO2 in the flue gas under the action of the oxidation air and the catalyst; controlling the pH value of the slurry in the absorption tower, the slurry temperature, the content of solid matters contained in the slurry and the retention time of the desulfurizer in the slurry pond; after the reaction is completed, performing vortex concentration and vacuum filtration to obtain a gypsum by-product; and adding wastewater produced in the process into a process water collection box for recycling. The method is simple, is easy to realize, has remarkable effect, provides a safe and proper treatment way for the dry / semidry desulfurization ash and has good economic and social benefits.

Description

technical field [0001] The invention belongs to the field of flue gas desulfurization, and in particular relates to a method for treating dry / semi-dry desulfurization ash by using a limestone-gypsum wet flue gas desulfurization process. Background technique [0002] Flue gas desulfurization in SO 2 Plays an important role in pollution prevention and control. According to the different desulfurization processes, the calcium desulfurization process is divided into wet method, dry method and semi-dry method, and the dry method / semi-dry method has the advantages of desulfurization products in dry powder form and low water consumption in the process. , no wet smoke emission, less corrosion, and strong adaptability to small and medium coal-fired units, etc., occupying a place in the desulfurization market. [0003] Due to the high Ca / S of dry / semi-dry flue gas desulfurization process, low utilization rate of desulfurization agent, slow reaction speed, and difficult process contro...

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Problems solved by technology

[0003] Due to the high Ca / S of dry / semi-dry flue gas desulfurization process, low utilization rate of desulfurization agent, slow reaction speed, and difficult process control, the chemical composition of desulfurization ash fluctuates greatly and the content of unstable components is high. Therefore, the utilization mode of desulfurization ash and The scope of application is strictly limited: (1) The properties of desulfurization ash are very unstable during the utilization process, such as CaSO 3 Oxidizes slowly in humid environment, decomposes in acidic environment and high temperature, Ca(OH) 2 and CaCO 3 Pyrolysis produces CaO, and f-CaO will cause volume expansion of cement and concrete during the hydration process; (2) Excessive sulfur content limits the use of desulfurized ash as cement and concrete admixtures, because in ordinary According to the national standard of cement, SO in cement 3 (3) The leaching toxicity of desulfurization ash exceeds the standard, which is a hazardous waste, and the safety and later stability of agricultural or building materials need to be further evaluated; (4) SiO 2 +Al 2 o 3 +Fe 2 o 3 If the content is too low, it will affect the chemical activity of desulfurization ash, and the MgO and ignition loss will be higher; (5) Desulfurization ash is easy to raise dust, and secondary pollution is prone to occur during transportation, storage and utilization

[0004] At present, the research on the characteristics and application of calcium sulfite desulfurization ash is not in-depth at home and abroad, and no technical approach for large-scale industrial utilization has been found. Environment, occupying land, causing secondary pollution, and directly affecting the application and promotion of dry / semi-dry desulfurization process

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