Modified phosphogypsum and its preparation method

Abstract

The invention discloses a modified phosphogypsum capable of avoiding environmental pollution caused by phosphogypsum produced in the phosphoric acid or phosphate fertilizer industry, and capable of using the phosphogypsum for roadbed materials, turning waste into treasure and a preparation method thereof. The modified phosphogypsum, including 84% to 94% CaSO 4 and 5% to 15% CaCO 3 . The preparation method of the modified phosphogypsum comprises steps, S1, dehydrating the phosphogypsum, the dehydration temperature is 150°C to 200°C; S2, stirring and breaking the phosphogypsum into powder; S3, air cooling the dehydrated phosphogypsum to room temperature ; then add CaCO to the phosphogypsum 3 , and makes CaCO 3 The mass percentage content is 3%; stirring makes phosphogypsum and CaCO 3 Mix well; S4, then to the mixed phosphogypsum and CaCO 3 CaCO 3 ; and make CaCO 3 The mass percentage content is 5% to 15%; stir and mix evenly. The modified phosphogypsum prepared by the modified phosphogypsum preparation method is used as a roadbed material, which can save land and avoid environmental pollution.

Description

technical field [0001] The invention relates to phosphogypsum, in particular to a modified phosphogypsum and a preparation method thereof. Background technique [0002] Here, phosphogypsum: refers to the solid waste residue produced when phosphate rock is treated with sulfuric acid in the production of phosphoric acid, and its main component is calcium sulfate. The main components of phosphogypsum are: CaSO 4 2H2O, in addition to a variety of other impurities. [0003] Phosphogypsum is generally in the form of powder, and its appearance is generally gray, gray, yellow, light green and other colors. It also contains organic phosphorus and sulfur-fluorine compounds. Its bulk density is 0.733-0.88g / cm3, and its particle diameter is generally 5-15um. The content of calcium sulfate dihydrate can generally reach about 70 to 90%, and the secondary components contained in it vary with the origin of phosphate rock. Generally, it contains phosphates and silicates of rock components ...

AI Technical Summary

Problems solved by technology

Under normal circumstances, 1 ton of phosphoric acid is produced by wet method, and 4.5 to 5.5 tons of phosphogypsum are produced. The quantity is very large, but the utilization rate is very low.

[0006] 3) The large discharge of phosphogypsum not only occupies a large amount of land, but also because phosphogypsum is soaked in rainwater for a long time, the soluble P and F in it are transferred to the environment through water as a medium, which will cause pollution of soil, water system and air

[0008] At present, when it is usually used as building materials such as building materials and boards, it will easily cause cracking due to impurities that are difficult to handle; at the same time, the stacking of phosphogypsum will pollute groundwater.

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