Method for preparing ultra-fine calcium sulfate crystal whisker by using phosphogypsum

A technology of calcium sulfate whisker and phosphogypsum, applied in the chemical industry, can solve the problems of high cost, uneconomical, and no use of environmental protection and the like

Active Publication Date: 2010-08-04
WENGFU (GRP) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These three patents use natural resources to produce calcium sulfate whiskers, which is costly, uneconomical, does not take advantage of environmental protection, and cannot solve the problem of phosphogypsum produced by wet-process phosphoric acid and piles up like mountains, which also cause environmental problems.
Moreover, these three methods of preparing whiskers are not suitable for phosphogypsum raw materials containing more impurities.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Superfine 5g of phosphogypsum to 0.1-10μm, add 95g of water, stir evenly, adjust the pH value to 4, place it in a hydrothermal reactor, react at 145°C and 2.5MPa for 4 hours, and filter while it is hot. The filter residue was dried at 250°C. Observed by scanning electron microscope, the granules completely disappeared, and the phosphogypsum was basically completely transformed into whiskers with a diameter of 0.1 μm and an aspect ratio of 70-80.

Embodiment 2

[0017] Superfine 5g of phosphogypsum to 0.1-10μm, add 1g of MgSO 4 and 1g of calcium sulfate dihydrate seed crystals, then add 95g of water, stir evenly, adjust the pH value to 4 with hydrochloric acid, place it in a hydrothermal reactor, react at 130°C and 3MPa for 4h, and suction filter while it is hot , The filter residue was dried at 120°C, observed with a scanning electron microscope, the particles completely disappeared, and completely transformed into whiskers with a diameter of 0.4 μm and an aspect ratio of 80-100.

Embodiment 3

[0019] Superfine 5g of phosphogypsum to 10-50μm, add 1g of MgSO 4 and 1g of calcium sulfate dihydrate seed crystals, then add 95g of water, stir evenly, adjust the pH value to 4, place it in a hydrothermal reactor, react at 130°C and 2.5MPa for 5h, and suction filter while it is hot. The filter residue was dried at 150°C, observed with a scanning electron microscope, the granules completely disappeared, and basically completely transformed into whiskers with a diameter of 0.3 μm and an aspect ratio of 70-90.

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Abstract

The invention discloses a method for preparing ultra-fine calcium sulfate crystal whiskers by using phosphogypsum. The method comprises that the phosphogypsum is ultra-fine treated to powder with grain size of 0.1-100 mum, water is added into the powder to prepare slurry with weight percent of 5-15 percent, pH value is regulated to be 3-5, reaction is kept for 3-5h at 125-145 DEG C and under 2-3MPa, pumping filtration is conducted when the obtained product is hot, and the filtered product is dried at 120-250 DEG C to obtain the calcium sulfate crystal whiskers. Moreover, crystal promoter with weight 0.10-0.20 time of the weight of the phosphogypsum and seed crystal with weight 0.1-0.2 time of the weight of the phosphogypsum can be added. The invention has the advantages of low production cost, simple production method and good comprehensive performance.

Description

technical field [0001] The invention relates to the field of chemical engineering, in particular to a method for preparing calcium sulfate whiskers. Background technique [0002] Phosphogypsum is an industrial waste produced during the production of wet-process phosphoric acid. In the traditional wet-process phosphoric acid manufacturing process, every 1t of wet-process phosphoric acid produced (in P 2 o 5 Total) by-product phosphogypsum is about 4-5 tons, and the annual discharge of phosphogypsum in the world is close to 200 million tons. But the actual utilization rate is less than 1 / 10 of the total. A large amount of phosphogypsum is stacked in the open air, occupying land and seriously polluting the environment, which has become a worldwide problem. The main component of phosphogypsum is calcium sulfate (dihydrate gypsum content is about 85%), and the impurity content varies with raw materials, process routes, and operating conditions. Among the impurities, soluble ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/62C30B29/46
Inventor 秦军于杰解田杨丽萍金翠霞谢占金田瑶珠秦舒浩
Owner WENGFU (GRP) CO LTD
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