Method for co-processing pellet desulfurized fly ash by wet desulphurization system

Abstract

The invention discloses a method for co-processing pellet desulfurized fly ash by a wet desulphurization system, which comprises the following steps of: pulping the pellet desulfurized fly ash, feeding one part of the pellet desulfurized fly ash and existing limestone slurry as a desulfurizing agent into an existing wet desulphurization absorption tower to prepare gypsum slurry, and taking the rest part of the pellet desulfurized fly ash as an alkaline precipitation accelerant in a deep oxidation process; enabling the gypsum slurry to pass through a gypsum cyclone to obtain overflow slurry and underflow slurry, standing the overflow slurry to obtain overflow supernate and an overflow solid-phase substance, and dehydrating the underflow slurry and the overflow solid-phase substance to obtain desulfurized gypsum; carrying out deep oxidation, flocculent precipitation and standing on the overflow supernate to obtain clear liquid and bottom mud; the clarified liquid is used for pelletizing desulfurization ash pulping; the bottom mud is treated by a wastewater cyclone to obtain front-section sludge and desulfurization wastewater, and the desulfurization wastewater enters a desulfurization wastewater treatment system to be treated. The method overcomes the defects that in the prior art, pellet desulfurized fly ash is low in proportioning amount, a slurry pond is prone to blistering and overflowing, desulfurized gypsum is deep in chroma and poor in grade, a desulfurization wastewater treatment system is large in sludge amount, and the slurry pond is prone to poisoning.

Description

technical field [0001] The invention relates to the technical field of flue gas desulfurization, in particular to a method for co-processing pellet desulfurization ash by a wet desulfurization system. Background technique [0002] Pellet desulfurization ash comes from the flue gas dry / semi-dry desulfurization device in the pellet preparation process of iron and steel enterprises. 3 , CaCO 3 , f-CaO, Ca(OH) 2 Other alkaline components, SiO 2 、Al 2 o 3 The content of ultra-fine fly ash is 3.5% to 20%, and the iron content is high, and harmful elements (chloride ions, inert impurities, and heavy metal elements, etc.) The disposal methods of group desulfurization ash are mainly piled up and discarded; in addition, there are some exploratory ways to use such as cement retarder, concrete admixture, wall material, mortar material, etc., or engineering filling, grading Materials, reinforced soft ground, etc., are mostly passive end treatment, and there are problems such as low...

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Problems solved by technology

The above methods all use desulfurization ash as a part of the desulfurization agent instead of limestone powder. When the ratio of desulfurization ash increases, it will have a negative impact on the existing wet system, mainly involving the following aspects: (1) Desulfurization ash The iron content in the ash is high and the color is dark, which cannot be effectively removed in the slurry system of the absorption tower, resulting in the deepening of the color of the by-products of gypsum, which brings difficulties to the subsequent comprehensive utilization; (2) the inert impurities and organic impurities in the desulfurization ash are harmful Limestone powder has a wrapping effect, which will reduce the desulfurization activity of limestone, cause reaction blockage, and affect the forward flow of the system; (3) The extremely fine particles in the desulfurization ash are continuously enriched, providing condensation nuclei for the foaming of the slurry, causing the slurry to overflow; (4) ) The concentration of chloride ions and heavy metal ions in the slurry is high, which causes slurry poisoning and reduces the desulfurization efficiency; (5) The impurity components in the desulfurization ash all enter the desulfurization wastewater and desulfurization gypsum dehydration system, which increases the load of wastewater treatment and dewatered sludge treatment (6) When the proportion of desulfurization ash is too high, the existing wet desulfurization system will suddenly increase the content of chloride ions, heavy metal elements, and calcium sulfite, resulting in a large load change and incomplete oxidation of the slurry pool , leading to difficulty in dehydration of gypsum, lower grade, and even shutdown of the existing desulfurization system

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