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A method for preparing high whiteness short columnar α-hemihydrate gypsum from desulfurized gypsum

A technology of hemihydrate gypsum and desulfurized gypsum, applied in chemical instruments and methods, calcium/strontium/barium sulfate, inorganic chemistry, etc., can solve problems such as secondary pollution, improve whiteness value, solve a large number of accumulations, improve The effect of applying value

Active Publication Date: 2019-05-21
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This process uses strong acid conditions and two dissolution and crystallization processes to successfully achieve the separation of colored impurities and product purification, which not only solves the problem of accumulation and secondary pollution of waste resource desulfurization gypsum, but also provides a new way for the production of gypsum with high whiteness and certain strength the way out

Method used

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  • A method for preparing high whiteness short columnar α-hemihydrate gypsum from desulfurized gypsum
  • A method for preparing high whiteness short columnar α-hemihydrate gypsum from desulfurized gypsum
  • A method for preparing high whiteness short columnar α-hemihydrate gypsum from desulfurized gypsum

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Embodiment 1: the specific operations are as follows

[0035] (1) Crystal transformation:

[0036]a. Mix concentrated hydrochloric acid, water, calcium chloride, and desulfurized gypsum according to water: concentrated hydrochloric acid (12mol / L): CaCl 2 : Desulfurized gypsum=100mL:8mL:1g:10g The prepared reaction slurry is placed in a three-necked flask, and heated to 100°C for 285min;

[0037] b. Let the slurry obtained in a. stand at a constant temperature of 25°C for 8 hours;

[0038] (2) Filter the slurry obtained in step (1), and wash with deionized water until neutral;

[0039] (3) Drying: Dry the product obtained in step (2) at 45°C for 10 hours to obtain the intermediate product, as shown in the attached figure 2 ;

[0040] (4) Water, intermediate product, NaCl, and succinic acid are prepared according to the mass ratio: water: intermediate product: NaCl: succinic acid=100:14:3:0.07 to prepare a reaction slurry, and adjust the acidity and alkalinity of the...

Embodiment 2

[0045] Embodiment 2: specific operation is as follows

[0046] (1) Crystal transformation:

[0047] a. Mix concentrated hydrochloric acid, water, calcium chloride, and desulfurized gypsum according to water: concentrated hydrochloric acid (12mol / L): CaCl 2 : The ratio of desulfurized gypsum=100mL:8mL:1g:10g is prepared and the reaction slurry is placed in a three-necked flask, and heated to 100°C for 285min;

[0048] b. Let the slurry obtained in a. stand at a constant temperature of 25°C for 8 hours;

[0049] (2) Filter the slurry obtained in step (1), and wash with deionized water until neutral;

[0050] (3) drying: drying the product obtained in step (2) at 45°C for 10 hours to obtain the intermediate product;

[0051] (4) Water, intermediate product, NaCl, and succinic acid are prepared according to the mass ratio: water: intermediate product: NaCl: succinic acid=100:16:3:0.07 to prepare a reaction slurry, and adjust the acidity and alkalinity of the slurry to pH =9; ...

Embodiment 3

[0054] Referring to the method in GB / T5950-2008, the R457 whiteness value (Wr) of the product measured is 88.22%. Too much middle affects the heat transfer and mass transfer of this process, and a small amount of colored impurities affects further separation. A slight drop, but still close to 90%. Embodiment 3: specific operations are as follows

[0055] (1) Crystal transformation:

[0056] a. Mix concentrated hydrochloric acid, water, calcium chloride, and desulfurized gypsum according to water: concentrated hydrochloric acid (12mol / L): CaCl 2 : The ratio of desulfurized gypsum=100mL:8mL:1g:10g is prepared and the reaction slurry is placed in a three-necked flask, and heated to 100°C for 285min;

[0057] b. Let the slurry obtained in a. stand at a constant temperature of 25°C for 8 hours;

[0058] (2) Filter the slurry obtained in step (1), and wash with deionized water until neutral;

[0059] (3) drying: drying the product obtained in step (2) at 45°C for 10 hours to obt...

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Abstract

The invention discloses a method for preparing high-whiteness stumpy alpha-semi-hydrated gypsum from desulfurization gypsum. The method comprises the following steps: adding concentrated hydrochloric acid, water, calcium chloride and desulfurization gypsum into a container to be mixed, heating to the temperature of 95-100 DEG C, ageing after the reaction is ended, filtering, and washing to be neutral; drying, mixing with water, NaCl and succinic acid, regulating the pH value of the slurry to be 7-12; and placing in a crystallization kettle, filtering after the reaction is ended, and drying, thereby obtaining the high-whiteness stumpy alpha-semi-hydrated gypsum. According to the method disclosed by the invention, waste desulfurization gypsum serves as a raw material, the obtained high-whiteness stumpy crystal can be applied to construction and building materials and other industries with high product whiteness requirement and used for appearance beautification, and the additional value is high.

Description

technical field [0001] The invention relates to a method for obtaining short columnar alpha-hemihydrate gypsum with high whiteness by utilizing dissolved crystallization and multiple crystal transformations. technical background [0002] Wet calcium-based desulfurization is the most widely used flue gas desulfurization process in coal-fired power plants today. The resulting desulfurized gypsum has problems such as dark color, high accumulation, groundwater pollution and low utilization rate. With the rapid development of the construction industry and building materials industry, the requirements for whiteness and strength of gypsum and its finished products are also increasing. Large-particle short columnar α-hemihydrate gypsum is currently recognized as high-strength gypsum, but short columnar α-hemihydrate gypsum made from desulfurized gypsum has a darker color, and its application range is greatly limited. Therefore, producing short columnar α-hemihydrate gypsum with hi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F11/46
CPCC01F11/466C01P2004/03C01P2004/61C01P2006/65
Inventor 曹吉林邵朵朵郭宏飞刘秀伍郜丽丽王志广张广林
Owner HEBEI UNIV OF TECH
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