CN110615630A

CN110615630A - Modified phosphogypsum cement coagulation regulator

Info

Publication number: CN110615630A
Application number: CN201810634200.0A
Authority: CN
Inventors: 白明科; 李海宏; 赵健
Original assignee: Yaobao Special Cement Technology Development Co Ltd
Current assignee: Yaobao Special Cement Technology Development Co Ltd
Priority date: 2018-06-20
Filing date: 2018-06-20
Publication date: 2019-12-27

Abstract

A modified ardealite cement setting modifier comprises 75-95% of ardealite, 5-15% of quicklime and 2.5-10% of anhydrous sodium sulphate by mass percent. The phosphogypsum is compounded with quick lime and anhydrous sodium sulphate to comprehensively modify the phosphogypsum, the pH value of the modified phosphogypsum reaches more than 7, and the content of soluble phosphorus is effectively reduced. The modified phosphogypsum is used for the cement retarder, the production process is simple, the problems of land occupation and environment pollution caused by phosphogypsum discharge are solved, and the cement production enterprises can realize win-win of economic benefit and social benefit, so the modified phosphogypsum is a cement retarder which is worth of popularization and application.

Description

Modified phosphogypsum cement coagulation regulator

Technical Field

The invention provides a modified phosphogypsum cement set retarder, in particular relates to a phosphogypsum set retarder for cement modified by industrial waste phosphogypsum, and belongs to the technical field of cement set retarders.

Background

In recent years, with the rapid development of building material industry and the wide application of gypsum in building material industry, natural gypsum resources are more and more in high demand. Desulfurized gypsum from power plants is also widely processed into gypsum products, resulting in the rising prices of natural gypsum and desulfurized gypsum as conventional cement set regulators, which puts a great pressure on the control of production costs in cement enterprises. The phosphogypsum is a byproduct in the industry of producing phosphoric acid or phosphate compound fertilizer by a wet method, contains trace phosphorus, fluorine, organic matters and other various impurities, and the existence of the impurities affects the use performance of the phosphogypsum, so that the comprehensive utilization of the phosphogypsum is severely restricted. For a long time, how to treat the phosphogypsum is an international technical problem, and at present, stacking measures are mainly adopted. For example, 10 million tons of phosphogypsum in Shanxi Weinan City are stocked in the open air for a long time, 15 million tons of phosphogypsum are discharged by phosphate fertilizer plants in Shanxi Weinan Hua county and are continuously discharged to the outside every day, and the far east fertilizer Limited company in Shanxi Han continuously discharges the phosphogypsum in the open air in the local county, and the total amount is about 6 million tons. The random stacking of the phosphogypsum not only causes great waste, but also causes great harm to the ecological environment.

If the industrial phosphogypsum is directly used as a cement setting modifier, the contained soluble phosphorus, fluorine and the like can delay the early hydration speed of the cement, so that the phosphogypsum cannot be correctly set and the strength is reduced, and therefore, the influence of harmful impurities such as the soluble phosphorus, the fluorine and the like on the performance of the cement needs to be eliminated through modification treatment. Von Enjuan et al proposed an ardealite-based cement setting regulator in CN104261716A, which consists of 92-97% of ardealite, 2.9-7% of modifier and 0.1-1% of dispersant, wherein the modifier consists of quicklime, calcined alunite and sodium metasilicate, and the dispersant consists of ethylene glycol, calcium lignosulfonate and tetramethylammonium iodide, but the composition is complex, the preparation process is complicated, the production cost is high, the ardealization can not be widely applied to industrial production, and the green development of energy conservation and consumption reduction can not be realized. Therefore, the Yaobei special cement group company Limited carries out modification test research and application development on the industrial byproduct phosphogypsum, develops the green and environment-friendly modified phosphogypsum with simple production process, uses a brand new formula, and completely replaces the original natural gypsum and desulfurized gypsum with the modified phosphogypsum, thereby changing waste into valuable, improving the economic benefit of enterprises, and consuming solid wastes to protect the environment.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a novel modified phosphogypsum.

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

a novel modified phosphogypsum cement set modifier is characterized in that: the paint consists of the following components in percentage by weight: 75-95% of phosphogypsum, 5-15% of quicklime and 2.5-10% of anhydrous sodium sulphate, wherein the sum of the weight percentages of the components is 100%, and the phosphogypsum is compounded with the quicklime and the anhydrous sodium sulphate to complete the comprehensive modification of the phosphogypsum.

Furthermore, the phosphogypsum is a waste material generated in the production of phosphoric acid in the phosphate fertilizer industry, wherein the content of dihydrate gypsum is 80-98 wt%, the water content is 20-30 wt%, the content of soluble phosphorus is more than 0.8 wt%, and the pH value is 2.0-5.0.

Furthermore, the calcium oxide content in the quicklime is 92 wt%, the water content is 0.18%, and the particle size is less than or equal to 0.5 mm.

Further, the air conditioner is provided with a fan,

the sodium sulfate content of the anhydrous sodium sulfate is 98 wt%, the pH value is 6-8, and the granularity is less than or equal to 0.3 mm.

The principle of the invention is as follows: phosphogypsum is acidic in different degrees, mainly because it contains impurities such as sulfuric acid, soluble phosphorus and fluorine in different amounts. The relationship between the pH value of phosphogypsum and the soluble phosphorus content is shown in figure 1, when the pH value is in the range of 3-5, the soluble phosphorus content is between 0.6% and 0.7%, and when the pH value exceeds 5, the soluble phosphorus content is remarkably reduced. At a pH of 7, the soluble phosphorus content is greatly reduced. Therefore, to control the setting time of cement, the soluble phosphorus content of phosphogypsum must be controlled, and only when the pH of phosphogypsum is not lower than 7, the soluble phosphorus in phosphogypsum does not prolong the setting time of cement. Based on the findings, the phosphogypsum is modified by the modifier, and quick lime and anhydrous sodium sulphate are selected for compounding through a large number of experiments, so that the pH value of the phosphogypsum is higher than 7, the requirement of construction requirements on the setting time of cement is met, and the cement setting modifier with excellent performance is developed.

The method comprises the following specific steps:

phosphogypsum in a storage yard is loaded into a hopper of a mixing station through a loader, and quick lime and anhydrous sodium sulphate respectively enter a powder bin through a bucket elevator. The phosphogypsum, the quicklime and the anhydrous sodium sulphate are measured by a speed-regulating measuring belt conveyor, conveyed to a feed inlet of a stirring device by a batching belt conveyor according to the weight percentage of 75-95: 5-15: 2.5-10, enter a stirrer for stirring, and are uniformly mixed under the stirring of double-channel spiral blades on two stirring shafts which are mutually reversed in the stirrer. And then, conveying the finished products from the discharge port to an inclined belt conveyor to a storage shed for storage.

The invention has the beneficial effects that: the modified phosphogypsum can be completely used as a coagulation regulator of cement, so that the production process is simple, the production cost is reduced, the ecological environment is protected, and certain economic benefit is brought.

Drawings

Figure 1 is a graph of the relationship of phosphogypsum pH to soluble phosphorus content.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description will be given with reference to the accompanying fig. 1 and preferred embodiments of a specific embodiment of a novel modified phosphogypsum cement set retarder according to the present invention. (the contents of this section are modified as determined by the claims)

Further, the air conditioner is provided with a fan,

The method comprises the following steps: the used phosphogypsum, quicklime and anhydrous sodium sulphate are all produced by Zhen' an branch of Yao Bai special cement group Limited, and are respectively metered by a metering belt conveyor (the mass percentage of the materials is phosphogypsum, carbide slag and alkali slag is 75-95: 5-15: 2.5-10) and then sent to a No. 1 raw material belt conveyor and a No. 2 raw material belt conveyor to enter a stirrer. After the stirring of the stirrer is uniform, the finished material is cooled by a discharge belt conveyor and then sent to a finished product warehouse for storage.

The addition ratio of the phosphogypsum in P.042.5 cement is 2.2%, and the addition ratio of the phosphogypsum in P.C32.5R cement is 1.8%. The strength of the phosphogypsum-based cement cementing material is measured according to GB/T17671-1999 Cement mortar Strength test method (150 method), the initial and final setting time is measured according to GB/T1346-2001, and the compressive strength and the initial and final setting time of each example are shown in Table 1 below.

Table 1 impact of modified phosphogypsum on cement properties

As shown in Table 1, after phosphogypsum is modified by using two materials, namely quicklime and anhydrous sodium sulphate, the requirements of the ordinary construction on the cement setting time (the initial setting time is less than or equal to 240min, and the final setting time is less than or equal to 300min) can be met by both P.042.5 cement and P.C32.5R cement.

As can be seen from Table 1, the quicklime or anhydrous sodium sulphate used alone can not meet the setting time requirements of cement in common construction crews, for example, 5 uses no anhydrous sodium sulphate, and the setting times of P.042.5 and P.C32.5R are longer (the initial setting time is more than 240min), for example, 6 uses no quicklime, and the setting times of P.042.5 and P.C32.5R are longer (the initial setting time is more than 240 min). In conclusion, through analysis of test results, the performance indexes meeting the design requirements finally determine the appropriate formula.

The modified phosphogypsum cement retarder of example 3 is used for preparing cement, and is prepared according to the following weight percentage: 85 percent of phosphogypsum, 10 percent of quicklime and 5 percent of anhydrous sodium sulphate. The initial setting time of the P.042.5 cement or the P.C32.5R cement is 199min and 222min respectively, the final setting time is 252min and 284min respectively, and other performances are optimal.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the present invention, and it will be apparent to those skilled in the art that various modifications and variations can be made in the spirit and principle of the present invention and that equivalent modifications and substitutions and the like are included in the scope of the present invention.

Claims

1. A modified phosphogypsum cement set modifier is characterized in that: the paint consists of the following components in percentage by weight: 75-95% of phosphogypsum, 5-15% of quicklime and 2.5-10% of anhydrous sodium sulphate; the sum of the weight percentages of the components is 100 percent.

2. The modified phosphogypsum cement set retarder according to claim 1, which is characterized in that: preferably, the phosphogypsum is waste material generated in the production of phosphoric acid in the phosphate fertilizer industry, wherein the content of dihydrate gypsum is 80-98 wt%, the water content is 20-30 wt%, the content of soluble phosphorus is more than 0.8 wt%, and the pH value is 2.0-5.0.

3. The modified phosphogypsum cement set retarder according to claim 1, which is characterized in that: the calcium oxide content in the quicklime is 92 wt%, the water content is 0.18%, and the particle size is less than or equal to 0.5 mm.

4. The modified phosphogypsum cement set retarder according to claim 1, which is characterized in that: the sodium sulfate content of the anhydrous sodium sulfate is 98 wt%, the pH value is 6-8, and the granularity is less than or equal to 0.3 mm.

5. The modified phosphogypsum cement set retarder according to claim 1, wherein the content of quicklime is 8-12%.

6. The modified phosphogypsum cement set retarder according to claim 1, wherein the anhydrous sodium sulphate content is 4-8%.

7. The modified phosphogypsum cement set retarder according to claim 1, which is characterized in that: the pH value of the modified phosphogypsum is 7-12, and the content of soluble phosphorus is less than or equal to 0.2 weight percent.

8. The preparation method of the modified phosphogypsum cement set-point modifier of any one of claims 1 to 7, wherein phosphogypsum is loaded into a hopper of a mixing station by a loader, quicklime and anhydrous sodium sulphate respectively enter a powder bin by a bucket elevator, the phosphogypsum, the quicklime and the anhydrous sodium sulphate are metered by a speed-regulating metering belt conveyor, are conveyed to a feed port of a stirring device by a proportioning belt conveyor according to the weight percentage of 75-95: 5-15: 2.5-10 to enter a stirrer to be stirred, are uniformly mixed under the stirring of double-channel helical blades on two stirring shafts which are mutually reversed in the stirrer, and are conveyed to a storage shed to be stored by a discharge port to an inclined belt conveyor.