Method for preparing high-strength alpha-semi-hydrated gypsum from flue gas desulfurization gypsum

Abstract

The invention belongs to the field of material science, and relates to a method for preparing high-strength alpha-semi-hydrated gypsum from flue gas desulfurization gypsum. The method comprises the following steps: 1) preparing desulfurization gypsum slurry: sufficiently mixing the flue gas desulfurization gypsum and water according to a solid-liquid mass ratio of 1: (4-10), and warming to 80-95 DEG.C; 2) adding a habit modifier to prepare mixed slurry: adding the habit modifier in the desulfurization gypsum slurry according to a condition that the mass ratio of the flue gas desulfurization gypsum to the habit modifier is 1: (0.5-1.5), wherein the habit modifier is a mixture of magnesium chloride hexahydrate and magnesium sulfate hexahydrate in a mass ratio of 1: (0.1-0.2), continuously warming to boil, and refluxing; 3) adding a crystal habit modifier: adding the crystal habit modifier in the mixed slurry obtained in the step 2) according to a condition that the mass ratio of the flue gas desulfurization gypsum to the crystal habit modifier is 1: (1%-5%); and 4) crystal transforming. The uniform short hexagonal prism alpha-semi-hydrated gypsum can be prepared by the method simple in process, the rupture strength reaches 14.4 MPa, and the compressive strength reaches 44.5 MPa.

Description

technical field

[0001] The present invention belongs to the field of material science. The invention relates to a preparation method for producing high-strength α-type hemihydrate gypsum with flue gas desulfurization gypsum as the main raw material. Background technique

[0002] In recent years, due to the requirements of environmental protection, flue gas desulfurization devices have been installed in major thermal power plants across the country. This brings another environmental protection problem: a large number of by-products-flue gas desulfurization gypsum are produced in the process of flue gas desulfurization, that is, FGD gypsum becomes solid waste. However, flue gas desulfurization gypsum contains more than 95% calcium sulfate dihydrate, Its grade is comparable to natural gypsum. It can be dehydrated into hemihydrate gypsum. Hemihydrate gypsum is divided into α-hemihydrate gypsum and β-hemihydrate gypsum. Compared with β-hemihydrate gypsum, α-hemihydrate gypsum...

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