Method for preparing desulfurized gypsum

Abstract

The invention discloses a method for preparing desulfurized gypsum, belonging to the technical field of flue gas desulfurization. The method comprises the following steps: taking desulfurizing slurry generated by flue gas wet desulfurization, adding a crystal grain increase agent into the desulfurizing slurry to carry out oxidization, separating out impurities, and dehydrating to obtain the desulfurized gypsum, wherein the crystal grain increase agent is at least one of surfactant, flocculant and inorganic salts. The method disclosed by the invention can greatly lower the water content of the desulfurized gypsum and enhance the purity of the desulfurized gypsum, thereby enhancing the quality of the desulfurized gypsum.

Description

technical field [0001] The invention relates to the technical field of flue gas desulfurization, in particular to a method for preparing desulfurized gypsum. Background technique [0002] Wet desulfurization process is currently the most widely used and most mature flue gas desulfurization technology, accounting for about 90% of the installed capacity of flue gas desulfurization (FGD) thermal power units. The wet desulfurization process includes limestone-gypsum method, white mud, carbide slag-gypsum method and other alkaline waste desulfurization processes, and the by-product of desulfurization is desulfurization gypsum. The main component of desulfurized gypsum is calcium sulfate dihydrate, which can be widely used in the preparation of cement, gypsum board, gypsum blocks and other construction products. Generally speaking, the resource utilization of desulfurized gypsum requires that the gypsum produced by the desulfurization system meet the conditions of moisture conten...

AI Technical Summary

Problems solved by technology

On the one hand, these impurities will affect the crystallization and growth of gypsum, resulting in fine grains of desulfurized gypsum, which is not conducive to the dehydration of gypsum; on the other hand, these impurities often have low density and high viscosity. When suction filtration is carried out, impurities form a layer of brown covering on the surface, which affects vacuum filtration; at the same time, some impurities are mixed between gypsum crystal grains, blocking the passage of free water between gypsum crystals, making it difficult to dehydrate gypsum ; In addition, higher impurity content will reduce the purity of desulfurized gypsum

[0006] 3. The solid content of the gypsum slurry sent to the dehydration equipment, if the solid content of the gypsum slurry is too low, the water content of the slurry will be relatively high, which will increase the load of the dehydration equipment, resulting in a high moisture content of the gypsum filter cake

[0008] 1. The desulfurization slurry is oxidized in the absorption tower, and the adjustment of parameters such as pH is restricted by the absorption process of sulfur dioxide. Secondly, the residence time of the slurry is limited by the volume of the absorption tower, and the time for grain formation and growth is relatively limited. At the same time, because the slurry is repeatedly passed through the circulation pump And spray layer reflux circulation, which is not conducive to the growth of gypsum grains

[0009] 2. Only the waste water system is used to discharge waste water to reduce impurities. The waste water discharged is the top flow of the hydrocyclone. Due to the limited effect of the hydrocyclone on the separation of impurities, the concentration of impurities in the waste water is low and has a relatively high concentration. Gypsum content, therefore, the wastewater treatment system has a large load and the removal of impurities is relatively limited

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