CN114162845A - Method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum - Google Patents
Method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum Download PDFInfo
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- CN114162845A CN114162845A CN202111642583.4A CN202111642583A CN114162845A CN 114162845 A CN114162845 A CN 114162845A CN 202111642583 A CN202111642583 A CN 202111642583A CN 114162845 A CN114162845 A CN 114162845A
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- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
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Abstract
本发明公开了一种利用磷石膏制备微米级无水硫酸钙的方法，是以磷石膏为原料，加水调浆后以硫酸作为反应试剂，在25‑80℃的环境下制备微米级无水硫酸钙。本发明是以磷石膏作为原料，加水制作成浆料后直接加硫酸，在常温或者低温下即可进行反应，能耗小，成本低；并且，本发明工艺中无其他添加剂，制备工艺非常简单，反应过程更加可控。更主要的是，本发明工艺在没有添加其他晶型控制剂的前提下，能够直接制备出短柱状的微米级无水硫酸钙，极大的简化了制备工艺，使得制备工艺更加可控。
The invention discloses a method for preparing micron-scale anhydrous calcium sulfate by using phosphogypsum. The phosphogypsum is used as a raw material, and after adding water to make a slurry, sulfuric acid is used as a reaction reagent, and the micron-scale anhydrous sulfuric acid is prepared in an environment of 25-80° C. calcium. In the present invention, phosphogypsum is used as a raw material, and water is added to make a slurry, and then sulfuric acid is directly added, and the reaction can be carried out at normal temperature or low temperature, with low energy consumption and low cost; in addition, there are no other additives in the process of the present invention, and the preparation process is very simple , the reaction process is more controllable. More importantly, the process of the present invention can directly prepare short columnar micron-scale anhydrous calcium sulfate without adding other crystal form control agents, which greatly simplifies the preparation process and makes the preparation process more controllable.
Description
Technical Field
The invention relates to a preparation method of anhydrous calcium sulfate, in particular to a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum.
Background
The anhydrous calcium sulfate is used as an auxiliary filler, and has wide application prospects in the fields of high polymer material fillers, inorganic material fillers, paper fillers, degradable material fillers, coatings, building gypsum and the like.
The traditional anhydrous calcium sulfate usually adopts natural gypsum or phosphogypsum as a raw material, and water in the raw material is removed under the condition of heating, so that the anhydrous calcium sulfate is obtained. However, natural gypsum or phosphogypsum is produced from gypsum (CaSO)4·2H2O) into plaster of paris (2 CaSO)4·H2O is CaSO4·1/2H2O) is requiredHeating to 150 ℃ and 170 ℃ to completely change into anhydrous calcium sulfate can be realized only by heating to about 400 ℃. Therefore, when the anhydrous calcium sulfate is prepared by the traditional calcining method, the energy consumption and the cost are high, and the large-scale processing and the large-scale application of the anhydrous calcium sulfate are not facilitated.
In order to reduce the dehydration temperature and reduce the energy consumption, researchers at present develop an acid-adding dehydration process, and the phosphogypsum is recrystallized by adding inorganic acid into the phosphogypsum, and the phosphogypsum is recrystallized to form anhydrous calcium sulfate crystals by the action of various added nucleating agents and/or surfactants. Although the reaction temperature can be reduced to a certain extent and the energy consumption can be reduced, the reaction temperature still needs to be about 100 ℃, and the problem of high energy consumption still exists when the phosphogypsum is used for producing anhydrous calcium sulfate on a large scale. In addition, most of the anhydrous calcium sulfate prepared at present is whisker-shaped, the length-diameter ratio is large, when the anhydrous calcium sulfate is used as a filler, the fusion degree with a base material is not high, and the application of the anhydrous calcium sulfate in the field of the filler is greatly limited, while in order to obtain short columnar, namely micron-sized anhydrous calcium sulfate, some disclosed prior art needs to add various additives into a reaction system to control the size of anhydrous calcium sulfate crystals, so that the preparation process of the anhydrous calcium sulfate becomes complicated, and the process is uncontrollable.
Based on the method, the preparation temperature of the anhydrous calcium sulfate is reduced, the energy consumption is reduced, the cost is reduced, and the preparation process and the crystal shape of the anhydrous calcium sulfate are improved, so that the crystallization process is more controllable, and the method is a research hotspot in the field.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum.
The technical scheme of the invention is as follows: a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the steps of taking phosphogypsum as a raw material, adding water, mixing slurry, taking sulfuric acid as a reaction reagent, and preparing the micron-sized anhydrous calcium sulfate at the temperature of 25-80 ℃.
The method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and reacting at the temperature of 25-80 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then drying to obtain the micron-sized anhydrous calcium sulfate.
In the method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum, after the sulfuric acid solution is added into the phosphogypsum slurry in the step (2), the liquid-solid ratio in the system is 2: 1-1: 2.
in the method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum, the liquid-solid ratio is 1: 2.
in the method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum, after the sulfuric acid solution is added into the phosphogypsum slurry in the step (2), the sulfuric acid accounts for 70-98% of the total mass of water and sulfuric acid in the system, and the reaction is carried out at normal temperature.
In the method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum, after the sulfuric acid solution is added into the phosphogypsum slurry in the step (2), the sulfuric acid accounts for 40-70% of the total mass of water and sulfuric acid in the system, and the heating temperature is 25-80 ℃ while the self-heat release is utilized and the external auxiliary heating is carried out.
In the method for preparing the micron-sized anhydrous calcium sulfate by using the phosphogypsum, the reaction time in the step (2) is 0.5-1 h.
Micron-sized anhydrous calcium sulfate prepared by the method.
The micron-sized anhydrous calcium sulfate prepared by the method is applied to polymer material fillers, inorganic material fillers, paper fillers, degradable material fillers, coatings and building gypsum.
The invention has the advantages of
The invention takes the phosphogypsum as the raw material, adds water to prepare slurry, then directly adds sulfuric acid, and can react at normal temperature or low temperature, thus having low energy consumption and low cost; in addition, the process of the invention has no other additives, the preparation process is very simple, and the reaction process is more controllable.
More importantly, the process can directly prepare the micron-sized anhydrous calcium sulfate on the premise of not adding other crystal form control agents, greatly simplifies the preparation process and enables the preparation process to be more controllable.
The key point of the invention is that when the sulfuric acid solution is added, the amount of externally introduced water is small, after a large amount of sulfuric acid solution is added, the reaction can be carried out through the heat released by sulfuric acid when meeting water or the small amount of externally assisted heating, the calcium sulfate dihydrate is promoted to be recrystallized after being dissolved, and the micron-sized anhydrous calcium sulfate is finally formed by combining a system with low water content on the basis of controlling the crystallization time.
Drawings
FIG. 1 is a microscopic morphology of micron-sized anhydrous calcium sulfate prepared in example 1 of the present invention;
FIG. 2 is a microscopic morphology of the micron-sized anhydrous calcium sulfate prepared in example 2 of the present invention;
FIG. 3 is a microscopic morphology of micron-sized anhydrous calcium sulfate prepared in example 3 of the present invention;
FIG. 4 is a microscopic morphology of micron-sized anhydrous calcium sulfate prepared in example 4 of the present invention;
FIG. 5 is a microscopic morphology of micron-sized anhydrous calcium sulfate prepared in example 6 of the present invention;
as can be seen from the drawings 1-5, the anhydrous calcium sulfate can be prepared by the process of the embodiment of the invention, and the anhydrous calcium sulfate crystals have smaller long diameter and length within 10 μm, and belong to micron-sized anhydrous calcium sulfate. Meanwhile, the anhydrous calcium sulfate prepared by the processes of example 1, example 2, example 3, example 4 and example 6 of the invention is subjected to crystal water detection according to the regulation of GB/T5484-2012 gypsum chemical analysis method, and the crystal water content is respectively 1.65%, 1.05%, 1.83%, 1.34% and 1.88%, which indicates that the obtained product is the anhydrous calcium sulfate.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention.
Example 1:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a concentrated sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and controlling the liquid-solid ratio of a system to be 1:2, sulfuric acid accounts for 98 percent of the total mass of water and sulfuric acid in the system, and the reaction is carried out for 0.5 hour at the temperature of 25 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The microstructure of the anhydrous calcium sulfate prepared in this example is shown in fig. 1.
Example 2:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a concentrated sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and controlling the liquid-solid ratio of a system to be 1:2, sulfuric acid accounts for 82 percent of the total mass of water and sulfuric acid in the system, and the reaction is carried out for 0.8 hour at the temperature of 25 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The micro-topography of the anhydrous calcium sulfate prepared in this example is shown in fig. 2.
Example 3:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a concentrated sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and controlling the liquid-solid ratio of a system to be 1:2, sulfuric acid accounts for 70 percent of the total mass of water and sulfuric acid in the system, and the reaction is carried out for 1 hour at the temperature of 50 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The micro-topography of the anhydrous calcium sulfate prepared in this example is shown in fig. 3.
Example 4:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and controlling the liquid-solid ratio of a system to be 3: 4, the sulfuric acid accounts for 50 percent of the total mass of the water and the sulfuric acid in the system, and the reaction is carried out for 1 hour at the temperature of 60 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The micro-topography of the micron-sized anhydrous calcium sulfate prepared in this example is shown in fig. 4.
Example 5:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), controlling the liquid-solid ratio of the system to be 1:1, and reacting the sulfuric acid solution for 0.8h at the temperature of 80 ℃ under the condition that the sulfuric acid accounts for 40% of the total mass of the water and the sulfuric acid in the system;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
Example 6:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), controlling the liquid-solid ratio of the system to be 1:2, and reacting the sulfuric acid solution for 0.5h at the temperature of 40 ℃ under the condition that the sulfuric acid accounts for 70% of the total mass of the water and the sulfuric acid in the system;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The micro-topography of the anhydrous calcium sulfate prepared in this example is shown in fig. 5.
Example 7:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), controlling the liquid-solid ratio of the system to be 1:2, and reacting the sulfuric acid solution for 0.5h at the temperature of 25 ℃ under the condition that the sulfuric acid accounts for 70% of the total mass of the water and the sulfuric acid in the system;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
Example 8:
a method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), controlling the liquid-solid ratio of the system to be 2:1, enabling sulfuric acid to account for 50% of the total mass of water and sulfuric acid in the system, and reacting for 0.5h at 70 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then conventionally drying to obtain the micron-sized anhydrous calcium sulfate.
The above description is only for the purpose of illustrating the present invention and the appended claims, and the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention.
Claims (9)
1. A method for preparing micron-sized anhydrous calcium sulfate by using phosphogypsum is characterized by comprising the following steps: the method is characterized in that phosphogypsum is used as a raw material, water is added for size mixing, sulfuric acid is used as a reaction reagent, and micron-sized anhydrous calcium sulfate is prepared at the temperature of 25-80 ℃.
2. The method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 1, which comprises the following steps:
(1) taking phosphogypsum as a raw material, adding water for size mixing to obtain phosphogypsum slurry;
(2) adding a sulfuric acid solution into the phosphogypsum slurry prepared in the step (1), and reacting at the temperature of 25-80 ℃;
(3) and (3) filtering the product after the reaction in the step (2) is finished, and then drying to obtain the micron-sized anhydrous calcium sulfate.
3. The method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 2, which is characterized in that: after the sulfuric acid solution is added into the phosphogypsum slurry in the step (2), the liquid-solid ratio in the system is 2: 1-1: 2.
4. the method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 3, wherein: the liquid-solid ratio is 1: 2.
5. the method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 2, which is characterized in that: after the step (2) is carried out, sulfuric acid solution is added into the phosphogypsum slurry, the sulfuric acid accounts for 70-98% of the total mass of water and sulfuric acid in the system, and the reaction is carried out at normal temperature.
6. The method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 2, which is characterized in that: after the sulfuric acid solution is added into the phosphogypsum slurry in the step (2), the sulfuric acid accounts for 40-70% of the total mass of the water and the sulfuric acid in the system, the self heat release is utilized, meanwhile, the external auxiliary heating is carried out, and the heating temperature is 25-80 ℃.
7. The method for preparing micron-sized anhydrous calcium sulfate using phosphogypsum according to claim 2, which is characterized in that: the reaction time of the step (2) is 0.5-1 h.
8. Micron-sized anhydrous calcium sulphate obtained by the process according to any one of claims 1 to 7.
9. Use of the micron-sized anhydrous calcium sulfate prepared by the method according to any one of claims 1 to 7 in high molecular material fillers, inorganic material fillers, paper fillers, degradable material fillers, coatings and building plasters.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117623654A (en) * | 2023-12-15 | 2024-03-01 | 贵州大学 | A method for preparing micron-grade anhydrous calcium sulfate using an acid-salt mixed system |
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