CN113735471A

CN113735471A - Phosphorus II type anhydrous gypsum, cementing material and preparation method thereof

Info

Publication number: CN113735471A
Application number: CN202111187347.8A
Authority: CN
Inventors: 朱聪; 彭家惠; 刘先锋; 易伟
Original assignee: Chongqing Jiebosi Gypsum Co ltd
Current assignee: Chongqing Jiebosi Gypsum Co ltd
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2021-12-03

Abstract

The invention belongs to the technical field of building materials, and particularly relates to phosphorus II type anhydrous gypsum and a cementing material and a preparation method thereof. The crystallinity of the phosphorus II type anhydrous gypsum is 90-96. The cementing material consisting of the phosphorus II type anhydrous gypsum has the advantages of high strength, good water resistance, stable volume and the like.

Description

Phosphorus II type anhydrous gypsum, cementing material and preparation method thereof

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to phosphorus II type anhydrous gypsum and a cementing material and a preparation method thereof.

Background

Phosphogypsum is a powdery solid which is off-white or yellowish-white and mainly exists in the forms of needle crystals, polycrystalline nucleus crystals, monodisperse platy crystals and compact crystal crystals. Phosphogypsum is a byproduct of wet-process phosphoric acid production, and mainly contains calcium sulfate dihydrate and a small amount of soluble phosphorus pentoxide (Ura, Yangyu, Lushengjun. phosphogypsum comprehensive utilization research [ J ], resource conservation and environmental protection, 2018(9):33-34, 37; Wang Shijuan. phosphogypsum comprehensive utilization discussion [ J ].

However, the traditional process adopts low temperature to prepare the building gypsum, and the prepared building gypsum contains a large amount of harmful impurities and has unstable phase composition, thereby causing apparent quality problems of large quality fluctuation, low strength, poor water resistance, mildew and the like of downstream products and seriously restricting the resource utilization of the phosphogypsum.

Disclosure of Invention

In view of the above, the present invention aims to provide phosphorus II type anhydrous gypsum with stable phase composition, low impurity content and few crystal defects.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the phosphorus II type anhydrous gypsum has a crystallinity of 90 to 96.

Further, the phosphorus II type anhydrite has a crystallinity of 93.

Furthermore, the content of type II anhydrous phase is more than or equal to 90.0 wt%.

Furthermore, the content of soluble phosphorus is less than or equal to 0.01 wt%, the content of eutectic phosphorus is less than or equal to 0.03 wt%, and the content of soluble fluorine is less than or equal to 0.01 wt%.

Further, the specific surface area of the phosphorus II type anhydrous gypsum is 400 +/-20 m²/kg。

The invention also aims to protect the preparation method of the phosphorus II type anhydrous gypsum, which comprises the following steps: drying the phosphogypsum until the water content is less than or equal to 5%, then calcining for 2h at 800 +/-50 ℃, cooling by air flow outside a hearth after sintering, grinding into powder, and aging for 3 days.

Further, the drying temperature is 45 +/-3 ℃.

The specific surface area of the powder is 400 +/-20 m²/kg。

The invention also aims to protect the cementing material, comprising water, cement, slag, a hydrating agent and phosphorus II type anhydrous gypsum, wherein the crystallinity of the phosphorus II type anhydrous gypsum is 90-96.

Further, the hydrating agent includes potassium sulfate and aluminum sulfate.

Furthermore, the hydrating agent comprises 0.3-0.9 part of potassium sulfate and 0.4-1.2 parts of aluminum sulfate.

Further, the cement includes portland cement.

Further, the cementing material comprises the following components in parts by mass: 30-50 parts of water, 3-10 parts of cement, 5-15 parts of slag, 0.7-2.1 parts of a hydrating agent and 100 parts of phosphorus II type anhydrous gypsum.

The invention has the beneficial effects that:

the phosphorus II type anhydrous gypsum phase of the invention has stable composition and can remove harmful impurities.

The invention also solves the technical problem of poor volume stability when the phosphorus II type anhydrous gypsum is prepared into a cementing material.

The preparation method is simple.

Drawings

FIG. 1 is an XRD pattern;

fig. 2 is an electron microscope scanning detection result diagram, wherein a and b are electron microscope scanning diagrams of the phosphogypsum adopted in the example 1 and the obtained product respectively.

Detailed Description

The examples are provided for better illustration of the present invention, but the present invention is not limited to the examples. Therefore, those skilled in the art should make insubstantial modifications and adaptations to the embodiments of the present invention in light of the above teachings and remain within the scope of the invention.

Example 1

The phosphorus II type anhydrous gypsum is prepared by the following steps:

drying phosphogypsum at 45 deg.C until water content is less than or equal to 5%, calcining at 800 + -50 deg.C for 2 hr, cooling to room temperature with air flow outside furnace chamber, and grinding into powder with specific surface area of 400 + -20 m²Powder/kg, aged for 3 days.

Comparative example 1

This comparative example differs from example 1 in that: the calcination temperature was 180 ℃.

Performance detection

XRD detection is carried out on the products prepared in the example 1 and the comparative example 1, and analysis is carried out by using jade software, and the result is shown in figure 1;

wherein, the XRD detection parameters are set as follows: the diffraction test step angle was 0.5 ° and the scanning speed was 4 °/min.

As can be seen from FIG. 1, the product obtained in comparative example 1 is a phosphorus hemihydrate gypsum phase, and the product obtained in example 1 is a phosphorus II type anhydrite phase; the phosphorus type II anhydrite of example 1 had a crystallinity of 93, whereas the phosphorus hemihydrate of comparative example 1 had a crystallinity of only 83. Therefore, the phosphorus II type anhydrous gypsum crystal has less defects and higher crystallization quality.

The phase composition analysis of the product obtained in example 1 was carried out according to the phase composition analysis method of GBT 36141-2018 building Gypsum, the results are shown in Table 1; the raw materials used in example 1 and the obtained product were subjected to electron microscope scanning, and the results are shown in fig. 2.

TABLE 1 phase composition

Species of	Two aqueous phases	Semi-aqueous phase	Anhydrous phase of type III	Anhydrous phase of type II
					Content/wt%	0	0	0	91.2

As can be seen from table 1, the product obtained in example 1 had a content of type II anhydrous phase of 91.2%, and contained no two-water phase, semi-water phase and type III anhydrous phase. This shows that the phase composition of the anhydrite form II containing phosphorus of the invention is stable.

As can be seen from FIG. 2, the surface of the product obtained in example 1 was smooth. As can be seen from the combination of Table 1 and FIG. 2, the phase composition of the phosphorus II type anhydrous gypsum of the present invention is stable, the impurity content is low, and the crystal defects are few.

According to the standard JC/T2073-.

TABLE 2 impurity content

Detecting content	Soluble phosphorus/wt%	Eutectic phosphorus/wt%	Soluble fluorine/wt%	Organic matter/wt%
					Phosphogypsum raw material	0.42	0.30	0.22	0.12
Comparative example 1	0.45	0.32	0.20	0.10
					Example 1	0.01	0.03	0.01	0

As can be seen from table 2, the content of impurities such as soluble phosphorus, eutectic phosphorus, soluble fluorine and organic substances in the product obtained in example 1 was significantly reduced as compared with the raw material and comparative example 1.

Example 2

A cementitious material consisting of: 35kg of water, 4kg of PO42.5 ordinary portland cement and S95-grade slag (the specific surface area is more than or equal to 400 m)²/kg)10kg, potassium sulfate 0.4kg, aluminum sulfate 0.7kg and 100kg of the phosphorus II type anhydrite obtained in example 1.

And (3) uniformly mixing the raw materials to obtain the cementing material.

Comparative example 2

This comparative example differs from example 2 in that: the using amount of the industrial pure potassium sulfate is 1.0kg, and the using amount of the industrial pure aluminum sulfate is 0.3 kg.

Performance detection

The dimensional change rate and crack resistance of the cement materials prepared in example 2 and comparative example 2 were measured, and the results are shown in table 3;

wherein, the detection method of the size change rate is JC/T313-2009 expansion cement expansion rate test method;

the method for detecting the cracking resistance is JC/T951-2005 cement mortar cracking resistance test method.

TABLE 3 test results

Detecting content	Example 2	Comparative example 2
			Rate of change in dimension/%)	0.02	0.07
Resistance to cracking	Without cracks	Has cracks

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. Phosphorus II type anhydrite is characterized in that the crystallinity is 90 to 96.

2. The phosphorus form II anhydrite of claim 1, having a crystallinity of 93.

3. The phosphorus type II anhydrite as claimed in claim 1 or 2, characterized in that the content of type II anhydrite phase is 90.0% by weight or more.

4. The phosphorus type II anhydrite as set forth in any one of claims 1 to 3, wherein the soluble phosphorus content is 0.01 wt.% or less, the eutectic phosphorus content is 0.03 wt.% or less, and the soluble fluorine content is 0.01 wt.% or less.

5. The phosphorus type II anhydrite as set forth in any one of claims 1 to 4, characterized in that the specific surface area is 400. + -.20 m²/kg。

6. A process for the preparation of anhydrous gypsum form II containing phosphorus as claimed in any one of claims 1 to 5, comprising the steps of: drying the phosphogypsum until the water content is less than or equal to 5%, then calcining for 2h at 800 +/-50 ℃, cooling by air flow outside a hearth after sintering, grinding into powder, and aging for 3 days.

7. The method according to claim 6, wherein the powder has a specific surface area of 400 ± 20m²/kg。

8. The cementing material is characterized by comprising water, cement, slag, a hydrating agent and phosphorus II type anhydrous gypsum, wherein the crystallinity of the phosphorus II type anhydrous gypsum is 90-96.

9. The cementitious material of claim 8, wherein the hydrating agent comprises potassium sulfate and aluminum sulfate.

10. A cementitious material according to claim 9 characterised in that the hydrating agent comprises, in parts by mass, potassium sulphate 0.3 to 0.9 parts and aluminium sulphate 0.4 to 1.2 parts.