Method for producing building gesso by using semi-hydrated phosphogypsum and dihydrate phosphogypsum

Abstract

The present invention discloses a method for producing building gesso by using semi-hydrated phosphogypsum and dihydrate phosphogypsum, and belongs to the field of building gypsum production, wherein the building gesso has characteristics of small water requirement of normal consistency and high strength. The method comprises processes of raw material calcination, grinding and aging, wherein the raw materials comprise, by weight, 5-60% of semi-hydrated phosphogypsum, and 40-95% of dihydrate phosphogypsum. According to the present invention, the match use of the semi-hydrated phosphogypsum and the dihydrate phosphogypsum is adopted, and the ratio of the semi-hydrated phosphogypsum to the dihydrate phosphogypsum is strictly controlled, such that the disadvantage of single use of the semi-hydrated phosphogypsum or the dihydrate phosphogypsum is overcome, performances of the semi-hydrated phosphogypsum and the dihydrate phosphogypsum can be supported each other, and the prepared building gesso has characteristics of small water requirement of normal consistency and high strength; and the phosphogypsum is adopted to replace the natural gypsum to produce the building gesso so as to reduce production cost, change the phosphogypsum waste into treasure, effectively treat pollution and hazard on the environment due to phosphogypsum waste, and provide good environmental benefits, social benefits and economic benefits.

Description

technical field [0001] The invention belongs to the field of building gypsum production, in particular to a method for producing building gypsum powder by utilizing hemihydrate and dihydrate phosphogypsum. Background technique [0002] Phosphogypsum is the solid waste slag discharged during the production of phosphoric acid, and every ton of P produced 2 o 5 4-5 tons of dry slag phosphogypsum can be obtained. According to the different wet-process phosphoric acid production processes, the by-product phosphogypsum composition is also different. For example, the main component of the by-product phosphogypsum in dihydrate phosphoric acid process is CaSO 4 2H 2 O, the main component of phosphogypsum by-product of the semi-aqueous phosphoric acid process is CaSO 4 1 / 2H 2 O. At home and abroad, there are many enterprises using the dihydrate process to produce phosphoric acid, so there are many studies on dihydrate phosphogypsum, and it has been widely used to replace natural...

AI Technical Summary

Problems solved by technology

The use of phosphogypsum dihydrate to prepare building gypsum powder has the following disadvantages: (1) Phosphogypsum dihydrate requires a lot of energy in the process of calcination into hemihydrate gypsum, part of the energy is used to dry the free water in the phosphogypsum, and the other part can It is used to remove 1.5 molecules of crystal water; (2) The standard consistency of building gypsum powder prepared by dihydrate phosphogypsum requires a lot of water and low strength, and the drying energy consumption is high when used to produce paper panels and blocks; (3) The building gypsum powder prepared by dihydrate phosphogypsum has a fast setting time, and the initial setting time is generally 3-5 minutes. When it is used to produce plaster plaster, the construction operation time is short, and it is necessary to add a retarder to prolong the setting time.

[0003] Compared with phosphogypsum dihydrate, since there are not many enterprises using the semi-aqueous process to produce phosphoric acid, there are very few documents on the preparation of gypsum powder directly using hemi-hydrate phosphogypsum. The foreign literature "Influence of the technological parameters on the structure and properties of hemi -hydrate phosphogypsum" records that although the industrial by-product phosphogypsum has a high crystallinity, its shape is irregular and its solubility is very low, so the gypsum powder prepared by direct drying has low strength. At present, although it has been controlled in the laboratory The cohesive hemihydrate phosphogypsum is prepared by the process, and the gypsum powder with excellent performance can be prepared only by drying the free water. However, this method is limited by the source of the raw ore and the content of impurities, and it is difficult to realize in industrial production.

Images