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Method for preparing high-strength gypsum from phosphogypsum

A technology of high-strength gypsum and phosphogypsum, applied in the field of building materials, can solve the problems of waste of resources, reduced preparation efficiency, high process control requirements, etc., and achieves the effect of standard consistency, small water consumption, good crystal morphology and superior cost performance.

Inactive Publication Date: 2019-07-23
CHINA THREE GORGES UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, there are still some problems in the preparation of high-strength gypsum from phosphogypsum, such as: the pretreatment of phosphogypsum. When the pretreatment technology is immature and the test conditions do not meet the requirements, it is easy to cause secondary pollution and waste resources. Harmful impurities such as soluble phosphate and fluoride affect the crystal transformation of dihydrate gypsum to hemihydrate gypsum crystals; the preparation of high-strength gypsum is relatively complicated, and the process control requirements are high. If the influencing factors are not strictly controlled during preparation, high-strength gypsum The preparation efficiency of high-strength gypsum will be reduced, which will affect the growth of crystal morphology of high-strength gypsum, resulting in lower strength of high-strength gypsum

Method used

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  • Method for preparing high-strength gypsum from phosphogypsum

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Embodiment 1

[0013] A method for preparing high-strength gypsum by utilizing phosphogypsum, comprising the following steps: 1) Pretreatment of phosphogypsum: take an appropriate amount of phosphogypsum, add tap water and wash 13 times for pretreatment according to the water-to-paste ratio of 1:2.5, so that the pH value is neutral 2) Preparation of phosphogypsum slurry: take polycarboxylate (sodium citrate) by weighing 0.06% according to the mass ratio of phosphogypsum and carry out single mixing, and mix the prepared crystal modifier and water with a solid-to-liquid ratio of 3:1 Put it into the pretreated phosphogypsum to prepare a thick slurry, and the viscosity of the slurry is controlled to be 0.50-0.55mpa·s; 3) Autoclave treatment: put the prepared slurry into an autoclave, and the autoclave temperature is 144°C 4) drying and grinding the autoclaved material: drying the autoclaved material at 110±5°C, and grinding to obtain high-strength gypsum powder.

Embodiment 2

[0015] A method for preparing high-strength gypsum by utilizing phosphogypsum, comprising the following steps: 1) Pretreatment of phosphogypsum: take an appropriate amount of phosphogypsum, add tap water and wash 13 times for pretreatment according to the water-to-paste ratio of 1:2.5, so that the pH value is neutral 2) Preparation of phosphogypsum slurry: take polycarboxylate (gelatin) by weighing 0.06% according to the mass ratio of phosphogypsum and carry out single blending, and the prepared crystal modifier and water are mixed into the pre-mixed Prepare a thick slurry from the treated phosphogypsum, and control the viscosity of the slurry to 0.50-0.55mpa·s; 3) Autoclave treatment: put the prepared slurry into an autoclave, and at an autoclave temperature of 144°C, Constant temperature for 6 hours; 4) Drying and grinding of autoclaved materials: After drying the autoclaved materials at 110±5°C, they are ground to obtain high-strength gypsum powder.

Embodiment 3

[0017] A method for preparing high-strength gypsum by using phosphogypsum, comprising the following steps: 1) pretreatment of phosphogypsum: take an appropriate amount of phosphogypsum, wash with water for many times, add quicklime to wash 10 times in total during the 7th and 8th water washes for pretreatment , make the pH value neutral; 2) prepare phosphogypsum slurry: take polycarboxylate (sodium citrate) by weighing 0.06% by phosphogypsum mass ratio and carry out single mixing, and crystal modifier and water are 3:1 The solid-to-liquid ratio is mixed into the pretreated phosphogypsum to prepare a thick slurry, and the viscosity of the slurry is controlled to be 0.50-0.55mpa·s; 3) Autoclave treatment: put the prepared slurry into an autoclave, Autoclaved at 144°C, constant temperature for 6 hours; 4) Drying and grinding of autoclaved materials: After drying the autoclaved materials at 110±5°C, grind them to obtain high-strength gypsum powder.

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Abstract

The invention provides a method for preparing high-strength gypsum from phosphogypsum, belonging to the technical field of building materials. The preparation method adopts a pressurized aqueous solution method and comprises the following steps: 1) phosphogypsum pretreatment, namely, taking a proper amount of the phosphogypsum, after adding tap water with a proper proportion for cleaning or washing with water for a plurality of times, adding quicklime for neutralization water washing for pretreatment until the pH value is neutral; 2) preparation of phosphogypsum slurry, namely, adding appropriate types and amounts of crystal transfer agents, and preparing the phosphogypsum slurry with appropriate water content; 3) autoclaved treatment, namely, autoclaving at an appropriate temperature (orpressure) for a certain period of time; and 4) drying and grinding of autoclaved materials. According to the invention, the high-strength gypsum with strength grades of alpha 25 and alpha 30 and whiteness of not less than 60 percent is prepared. Therefore, the preparation of the high-strength gypsum from the phosphogypsum solves the problem of massive accumulation of the phosphogypsum, develops the resource utilization of the phosphogypsum, but also save resources, improves the environment, and has important social and economic benefits.

Description

technical field [0001] The invention relates to a method for preparing high-strength gypsum from phosphogypsum, which belongs to the technical field of building materials. Background technique [0002] Phosphogypsum is a precipitate mainly composed of calcium sulfate dihydrate discharged during the production of wet-process phosphoric acid. For every ton of phosphoric acid produced, about 4.5 to 5.5 tons of phosphogypsum are discharged. With the increase of phosphate fertilizer production, the stockpiling of phosphogypsum is increasing day by day, which not only occupies a large amount of land, increases costs, wastes resources, but also causes serious environmental pollution. Phosphogypsum can be used to prepare α- and β-type hemihydrate under different conditions, but β-type hemihydrate has low strength and poor fluidity. Compared with β-type hemihydrate, its products have high strength, light weight, Heat insulation, fire prevention, no pollution, long service life, etc....

Claims

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Application Information

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IPC IPC(8): C04B11/26C04B11/00C04B11/032
CPCC04B11/005C04B11/032C04B11/26
Inventor 彭艳周张亚利徐港刘冬梅高德军刘让新李国刚刘金娥史宏宇赵帅玉霞
Owner CHINA THREE GORGES UNIV
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