Method for phosphogypsum pretreatment for the preparation of high-strength gypsum

Abstract

The invention relates to a pretreatment method for phosphogypsum used for preparation of high-strength gypsum. According to a technical scheme in the invention, the method comprises the following steps: adding water into phosphogypsum to prepare slurry, then adding a detergent assistant, carrying out uniform mixing under stirring and then carrying out primary ultrasonic concussion and washing so as to obtain primary ultrasonically-mixed liquid; adding a cleaning compound into the primary ultrasonically-mixed liquid, carrying out uniform mixing under stirring and then carrying out secondary ultrasonic concussion and washing so as to obtain secondary ultrasonically-mixed liquid; and subjecting the secondary ultrasonically-mixed liquid to vacuum pumping filtration and carrying out vacuum drying on a filter cake so as to obtain pretreated phosphogypsum.

Description

technical field [0001] The invention relates to the field of phosphorus chemical industry, in particular to a method for pretreatment of phosphogypsum. Background technique [0002] The raw materials for the production of high-strength gypsum are mainly natural gypsum and desulfurized gypsum. The preparation of high-strength gypsum from phosphogypsum is still in the experimental stage, and there are few reports on its industrialization. [0003] Phosphogypsum is a by-product of sulfuric acid decomposition of phosphate rock to produce phosphoric acid. The building materials industry is an important application field of phosphogypsum. Phosphogypsum can be widely used in the preparation of cementitious materials, gypsum blocks, and plates, especially in The preparation of high-strength gypsum has good application prospects and can effectively reduce costs. But phosphogypsum contains many harmful impurities such as phosphorus, fluorine, and organic matter, which are the most im...

AI Technical Summary

Problems solved by technology

This process uses chemically modified phosphogypsum, and the phosphogypsum obtained after calcination has stable performance and reliable quality, which can consume a large amount of phosphogypsum and reduce environmental pollution. However, this method requires a drying temperature of 360-450°C. Dry until the water content is below 2%, and the calcination temperature is 200-240°C. The temperature requirement is high and the products produced are mainly for building gypsum, so it is difficult to realize a large number of industrial promotion and application.

[0005] Patent CN102731001A provides a phosphogypsum composite pretreatment process. This invention sequentially performs sieving, water washing, neutralization, flotation and suction filtration operations on the phosphogypsum slag directly discharged from chemical enterprises. The circulating water in this treatment method comes from The wastewater produced by phosphate rock ball milling or phosphoric acid washing process in chemical fertilizer plants contains more soluble phosphorus and organic impurities, which makes the pretreatment of phosphogypsum cumbersome, increases the consumption of alkali neutralizers, and increases the impurities in the finished product after treatment. , the coagulation time is prolonged, the structure is loose, and the strength is reduced during the later use of the finished product, which does not achieve the purpose of pretreatment