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A method of producing gypsum whiskers with hexagonal cross-section and low phosphorous content

A gypsum whisker, hexagonal technology, applied in chemical instruments and methods, single crystal growth, single crystal growth and other directions, can solve problems such as corrosion, limited source of raw materials, limited application scope, etc.

Active Publication Date: 2016-05-11
QINGDAO UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of nitric acid and hydrochloric acid can speed up the decomposition of phosphate ore, but the source of raw materials is limited and cannot be widely used. In addition, there are serious corrosion problems. At the same time, due to the reaction ≤ 90°C, almost all of the products made by these methods are quadrilateral in cross section, chemical The needle-shaped phosphogypsum composed of dihydrate gypsum, if used as a building material, must be roasted and dehydrated, which consumes a lot of energy to make hemihydrate gypsum before it can be used.
In addition, if the content of phosphorus in gypsum is high, it will affect the crystal structure of gypsum, reduce the mechanical properties of finished products, and limit its application range.

Method used

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  • A method of producing gypsum whiskers with hexagonal cross-section and low phosphorous content

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Embodiment 1

[0027]A method of making whiskers of gypsum hemihydrate in phosphoric acid. It includes the steps of preparing calcium phosphate solution, reacting calcium phosphate with sulfuric acid, preparing hemihydrate gypsum whiskers and the like. The preparation step of calcium phosphate solution is to use 480ml concentration to be 30% (P 2 o 5 ) of industrial phosphoric acid with 40 grams of phosphate rock (P 2 o 5 32%) for leaching chemical reaction, the temperature is controlled at 85°C, after 2 hours of reaction, the liquid phase is separated and filtered, and the filter residue is left for the next round to react with industrial phosphoric acid. The filtrate contains Ca 2+ =0.63mol / L calcium phosphate solution. Under stirring conditions, to 200ml Ca 2+ =0.63mol / L calcium phosphate solution, add 1.0ml of 1.0‰ polyacrylamide, after mixing, gradually add 40 grams of 30% sulfuric acid solution, stir and react at 93°C for 120 minutes to form gypsum whiskers suspended in phosphor...

Embodiment 2

[0029] A method of making low phosphorus content hemihydrate gypsum whiskers in phosphoric acid. It includes the steps of preparing calcium phosphate solution, reacting calcium phosphate with sulfuric acid, preparing hemihydrate gypsum whiskers and the like. The preparation step of calcium phosphate solution is with embodiment 1. Take 200mlCa 2+ =0.63mol / L calcium phosphate solution, add 1.0‰ polyacrylamide 1.0ml under stirring condition, gradually add 40 grams of sulfuric acid solution with a concentration of 30% after mixing, stir and react at 103°C for 30 minutes, Gypsum whiskers are formed suspended in phosphoric acid. The gypsum whisker suspension was filtered, washed three times with water, and dried at 110° C. to obtain 32.4 grams of gypsum whisker hemihydrate. Analysis of phosphorus pentoxide (P 2 o 5 ) content is 0.291%, and the crystal form is hexagonal rod.

Embodiment 3

[0031] A method of making low phosphorus content anhydrite whiskers in phosphoric acid. It includes the steps of preparing calcium phosphate solution, reacting calcium phosphate with sulfuric acid, preparing anhydrous gypsum whiskers and the like. The preparation step of calcium phosphate solution is to use the concentration that 480ml obtains after the gypsum whisker is produced in embodiment 2 to be 30% (P 2 o 5 ) of phosphoric acid, first react with the primary filter residue filtered out in Example 1 at 85°C for 1 hour, filter, wash the filter residue, and dry to obtain 3.81 grams of the secondary filter residue, where P 2 o 5 The content is 2.4%. Continue to react the filtered solution (semi-acid for short) with phosphate rock powder at 85°C for 2 hours, filter and separate the liquid phase to obtain Ca-containing 2+ It is 0.87mol / L calcium phosphate solution. Add 100ml of 0.87mol / L calcium phosphate solution gradually into 20g of 40% sulfuric acid solution, and cont...

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Abstract

The invention relates to a method for manufacturing a gypsum whisker with a hexagonal cross section and low phosphorus content. The method comprises the following steps of calcium phosphate solution preparation, reaction of the calcium phosphate solution and sulfuric acid and preparation of the hemihydrate or gypsum whisker. The method has the advantages that the growth time of the whisker can be reduced; the phosphorus pentoxide content in the gypsum whisker is reduced to below 0.3% and the cross section of the obtained gypsum whisker is hexagonal, so that the obtained gypsum whisker has good mechanical property and can meet high requirements and have wide application range; in the meantime, macromolecule surface modifiers such as polyacrylamide are added, so that the gypsum whisker is smooth in surface and soft in hand feel to benefit the popularization and the application to high molecular materials strengthening and wood pulp papermaking replacement.

Description

【Technical field】 [0001] The invention belongs to the technical field of gypsum whisker production, and more specifically relates to the improvement of the method for by-producting gypsum whiskers in wet-process phosphoric acid. 【Background technique】 [0002] Gypsum whiskers refer to fibrous single crystals with fixed cross-sectional shape, complete shape, perfect internal structure, and aspect ratio of 5-1000. In the world, gypsum whiskers are basically produced by hydrothermal method, and there are several kinds of semi-hydrated and anhydrous. Gypsum whiskers are mainly used as reinforcing agents or functional fillers in resins, rubber, coatings, and papermaking, and can also be used in friction materials, building materials, sealing materials, heat preservation and flame retardant materials, etc. [0003] The applicant's prior invention patent ZL200410024348.0 relates to a "method for producing gypsum whiskers in phosphoric acid", which contains H 3 PO 4 , Ca 2+ The ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C30B7/14C30B29/62C30B29/46
Inventor 陈学玺陈春光
Owner QINGDAO UNIV OF SCI & TECH
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