CN113354376B - Phosphogypsum-based aggregate and preparation method thereof - Google Patents
Phosphogypsum-based aggregate and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/10—Lime cements or magnesium oxide cements
- C04B28/12—Hydraulic lime
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/36—Inorganic materials not provided for in groups C04B14/022 and C04B14/04 - C04B14/34
- C04B14/365—Gypsum
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/14—Waste materials; Refuse from metallurgical processes
- C04B18/141—Slags
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/12—Multiple coating or impregnating
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00017—Aspects relating to the protection of the environment
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention discloses a phosphogypsum-based aggregate and a preparation method thereof, belonging to the technical field of road building materials. The phosphogypsum-based aggregate is prepared by mixing powder A and solution B into balls; the powder A comprises: 50-80% of phosphogypsum, 15-45% of waste residue powder and 3-6% of alkaline activator; the solution B comprises 1-2% of sodium hexametaphosphate, 0.1-0.2% of cellulose ether and the balance of water. The preparation method comprises the following steps: 1) mixing phosphogypsum, slag powder and an alkaline activator to obtain powder A; 2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B; 3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the granulator to be mixed with the powder A, and granulating to obtain an aggregate; 4) and (3) curing the aggregate, and then soaking in water for curing to obtain the phosphogypsum-based aggregate. The invention realizes short maintenance period and high strength of the phosphogypsum-based aggregate.
Description
Technical Field
The invention relates to the technical field of road building materials, in particular to a phosphogypsum-based aggregate and a preparation method thereof.
Background
Phosphogypsum is solid waste residue generated in the process of producing phosphoric acid industrially, and the main component of the phosphogypsum is calcium sulfate dihydrate (Ca) 2 SO 4 ·2H 2 O), and further contains various other impurities. The data show that every 1 ton of phosphoric acid produced (in P) 2 O 5 On a dry basis) will simultaneously produce 4.5-5 tons of phosphogypsum (on a dry basis of dihydrate gypsum). The annual output of the phosphogypsum in China is about 3500 million tons, which is tired ofThe discharge capacity reaches hundreds of millions of tons, the yield is equivalent to the annual yield of natural gypsum, and the gypsum becomes the most industrial byproduct gypsum in China. A large amount of waste residues are accumulated to form a phosphogypsum storage yard, which not only occupies cultivated land, but also pollutes the environment. But the effective utilization rate of the existing phosphogypsum is less than 30 percent, and a series of problems caused by the huge discharge of the phosphogypsum cannot be effectively solved.
The aggregate crushed from natural stones is one of the important raw materials for the construction of the traffic infrastructure in China. Since the innovation is open, China has built a road network of 500 kilometers. The road building material supports the rapid development of economic construction, and causes the problems of environmental deterioration, resource shortage, energy consumption and the like. The highway construction in China consumes 10 hundred million tons of sand and stone materials every year, and the environmental load is large. The phosphogypsum is prepared into the aggregate for road construction, so that the environmental problem caused by phosphogypsum stockpiling can be solved, the problem of shortage of natural aggregate can be solved, and green mountains of green trees can be protected.
Therefore, various novel approaches for recycling the phosphogypsum solid waste are continuously explored.
The ardealite-based aggregate prepared in the prior art has the problems of long maintenance period and low strength.
Disclosure of Invention
The invention aims to overcome the technical defects, provides a phosphogypsum-based aggregate and a preparation method thereof, and solves the technical problems of long curing period and low strength of the phosphogypsum-based aggregate in the prior art.
In order to achieve the technical purpose, the technical scheme of the invention provides a phosphogypsum-based aggregate and a preparation method thereof.
A phosphogypsum-based aggregate is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 50-80% of phosphogypsum, 15-45% of waste residue powder, 3-6% of alkaline activator and 100% of the total;
the solution B comprises 1-2% of sodium hexametaphosphate, 0.1-0.2% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 25-30% of the mass of the powder A.
Further, the waste slag powder is slag powder.
Further, the waste slag powder is a mixture of slag powder and coal ash powder, and comprises 5% -15% of slag powder and 10% -30% of coal ash powder.
Further, the alkaline activator is one or more of portland cement clinker, quick lime, sodium hydroxide, sodium aluminate and sodium silicate.
The invention also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder and an alkaline activator according to the proportion of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the granulator to be mixed with the powder A, and granulating to obtain an aggregate;
4) and (3) curing the aggregate, and then soaking in water for curing to obtain the phosphogypsum-based aggregate.
6. The method of claim 5, further comprising, after step 4): spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate obtained in the step 4).
Further, in step 4), the soaking and curing includes: and putting the solidified aggregate into normal-temperature water for curing for 14-28 days.
Further, in step 4), the soaking and curing includes: and putting the solidified aggregate into water with the temperature of 40-80 ℃ for curing for 7-14 days.
Further, in step 4), curing the aggregate specifically includes: and naturally stacking and curing the aggregate for 1-2 days.
Further, 300-600g of the water-soluble organosilicon is sprayed per ton of the phosphogypsum-based aggregate.
Compared with the prior art, the invention has the beneficial effects that: according to the phosphogypsum-based aggregate provided by the invention, under the coordination of all components, the alkalinity and the hydration activity of a hydration system are improved by adding an alkaline activator, the alkaline activator provides hydroxide ions to promote the hydrolysis of slag powder so as to generate hydrated calcium silicate gel and ettringite, hydration products are mutually crosslinked and wrap a large amount of phosphogypsum which does not participate in hydration reaction, so that the strength of the cementation system is generated, and the early strength of the aggregate is improved; the sodium hexametaphosphate and the cellulose ether are doped to play a role in water retention and thickening, the liquid B is sprayed and coated on the surface of the powder in the balling process to improve the cohesiveness of the powder, increase the early cohesion of the aggregate powder and accelerate the agglomeration and balling of the powder, in addition, the liquid B is hydrolyzed in aqueous solution to show alkalescence and has a promoting effect on hydration reaction, so that the strength of the phosphogypsum-based aggregate is improved, the crushing value is as low as 21.8 percent, the maintenance period of the aggregate is shorter under the matching of all components and can be as low as 7 days, and the short maintenance period and the high strength of the phosphogypsum-based aggregate are realized.
According to the preparation method of the phosphogypsum-based aggregate, the sodium hexametaphosphate and the cellulose ether are added into water to be dissolved to prepare the solution B, the solution B is mixed with the powder A in a spraying mode, all components of the solution B are fully contacted and uniformly mixed with the powder A, then the mixture B is pelletized to prepare the aggregate, and then the aggregate is cured and soaked for curing to obtain the phosphogypsum-based aggregate, under the combination of all components and process conditions, the curing time can be shortened to 1 day, and the soaking and curing time can be shortened to 7 days to obtain the phosphogypsum-based aggregate with high strength; in addition, water-soluble organic silicon is sprayed on the surface of the aggregate to fill pores on the surface of the aggregate, so that the water absorption is reduced and is as low as 1.2%.
Drawings
FIG. 1 is a pictorial representation of a phosphogypsum-based aggregate made in example 1 of the present invention.
Fig. 2 is a gradation design curve in application example 1 of the present invention.
FIG. 3 is a cement stabilized base mix gradation design curve in application example 2 of the present invention.
Detailed Description
The specific embodiment provides a phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into balls; the powder A comprises the following components in percentage by mass: 50-80% of phosphogypsum, 15-45% of waste residue powder, 3-6% of alkaline activator and 100% of the total;
the solution B comprises 1-2% of sodium hexametaphosphate, 0.1-0.2% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 25-30% of the mass of the powder A;
wherein the alkaline excitant is one or more of portland cement clinker, quick lime, sodium hydroxide, sodium aluminate and sodium silicate.
Further, in certain embodiments, the waste slag powder is a slag powder.
In still other embodiments, the waste slag powder is a mixture of slag powder and coal ash powder, and comprises 5% -15% of slag powder and 10% -30% of coal ash powder. And part of fly ash is used for replacing mineral powder, so that the cost is reduced.
The alkali activator is one or more of portland cement clinker, quick lime, sodium hydroxide, sodium aluminate and sodium silicate. In the phosphogypsum-slag cement hydration system, calcium ions and sulfate ions are provided by phosphogypsum, silicon-aluminum oxides are improved by slag powder, hydroxide ions are provided by an alkaline activator so as to promote the hydrolysis of the slag powder, thereby generating hydrated calcium silicate gel and ettringite, and hydration products are mutually crosslinked and wrap a large amount of phosphogypsum which does not participate in hydration reaction so as to ensure that the cementation system generates strength, so that the activity and the alkalinity of the alkaline activator have important influence on the early strength of the aggregate. Compared with silicate cement, the quicklime generates new ecological Ca (OH) in the digestion process 2 The material has stronger activity, releases a large amount of heat at the same time, can improve the system temperature, quickens the pozzolanic reaction rate and improves the early strength of aggregate; and the sodium hydroxide is used as strong alkali, and the lower mixing amount of the sodium hydroxide can meet the alkaline requirement of a hydration system. Compared with the method using pure portland cement as the alkali activator, the method using the mixture of multiple alkali activators can obviously improve the early strength of the cement, and simultaneously, the cost of the quicklime can be reduced by doping the quicklime.
The specific embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder and an alkaline activator according to the proportion of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the granulator to be mixed with the powder A, and granulating to obtain an aggregate; the running rotating speed of the ball mill is 10r/min-40 r/min;
4) naturally stacking and curing the aggregate for 1-2 days, and then soaking and curing to obtain the phosphogypsum-based aggregate; the soaking curing can be that the cured aggregate is put into normal-temperature water for curing for 14-28 days; the soaking curing can also be curing the cured aggregate in water at 40-80 ℃ for 7-14 days. Curing in water at normal temperature for 14 days, or in water at 40-80 deg.C for 7 days, and the curing time can be prolonged properly in different embodiments, and the curing temperature is preferably 60 deg.C; soaking and curing at 40-80 ℃ to improve the early strength;
5) spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, wherein each ton of the phosphogypsum-based aggregate is sprayed with 300-600g of the water-soluble organic silicon, and the water-soluble organic silicon can be diluted by water until the mass concentration of the water-soluble organic silicon is 50-60%. Water-soluble organic silicon is sprayed on the surface of the aggregate after curing and forming, so that the surface of the aggregate is more compact, the excessive absorption of the aggregate to asphalt in the road construction process is reduced, the effective asphalt content is improved, the consumption of the asphalt is reduced, and the cost is reduced.
The aggregate prepared by the phosphogypsum slag cement system has a rough surface, contains more pores, has the water absorption rate of more than 20 percent, and can absorb a large amount of asphalt in an asphalt mixture system, so that the effective asphalt content is reduced, the oilstone ratio is indirectly improved, and the cost is increased. And water-soluble organic silicon is sprayed on the surface of the aggregate after curing and forming, so that the surface of the aggregate is more compact, the redundant absorption of the aggregate to asphalt is reduced, the effective asphalt content is improved, the consumption of the asphalt is reduced, and the cost is reduced.
The hydration reaction in the phosphogypsum slag cement system determines the early strength of the aggregate, the hydration reaction rate is greatly influenced by the temperature, and the early hydration reaction rate can be accelerated and the early strength can be improved by properly raising the temperature. The test proves that: under the condition of the same proportion, the unconfined compressive strength of a test piece cured at 60 ℃ for 7 days can reach 3 times of that of the test piece cured at normal temperature.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the following examples, the phosphogypsum is an industrial byproduct of wet-process phosphoric acid production in enterprises, and the main chemical component of the phosphogypsum is dihydrate gypsum (CaSO) 4 ·2H 2 O), the specific surface area is 36.9m 2 Per kg and above, the content of absorbed water is 4-30 percent, and the content of crystal water is 16-20 percent; the physical parameters of the slag powder meet S95 and above; the physical products of the cement clinker are up to 42.5 cement.
Example 1
The embodiment provides an early strength phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 80% of phosphogypsum, 15% of slag powder, 4% of silicate cement clinker and 1% of quicklime;
the solution B comprises 1% of sodium hexametaphosphate, 0.1% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 25% of that of the powder A.
The embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder, portland cement clinker and quicklime according to the proportion of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a balling machine, and continuously spraying the solution B into the powder A in the balling machine to ball to obtain an aggregate; the running rotating speed of the ball mill is 30 r/min;
4) naturally stacking and curing the aggregate for 1 day, and then putting the cured aggregate into water at 60 ℃ for curing for 7 days to obtain the phosphogypsum-based aggregate;
5) and (2) spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, spraying 300g of water-soluble organic silicon on each ton of the phosphogypsum-based aggregate, and naturally airing to obtain an aggregate finished product, wherein the purity of the water-soluble organic silicon is 100%, and the water-soluble organic silicon is diluted by adding water until the mass concentration is 50% for use.
Various performance indexes of the early-strength phosphogypsum-based aggregate prepared by the embodiment can meet the national standard JTG E42-2005 road engineering aggregate test regulation and JTG E20-2011 road engineering asphalt and asphalt mixture test regulation. The apparent density of the phosphogypsum-based aggregate is 2.842g/cm 3 The bulk density of the wool is 1.627g/cm 3 The water absorption rate is 1.2 percent, the crushing value is 21.8 percent, the finished aggregate product is shown in figure 1, and the smooth particles on the surface of the phosphogypsum-based aggregate are uniform as can be seen from figure 1.
Example 2
The embodiment provides an early strength phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 70% of phosphogypsum, 10% of slag powder, 10% of coal ash powder, 4% of portland cement clinker, 0.5% of sodium hydroxide and 0.5% of sodium aluminate;
the solution B comprises 1% of sodium hexametaphosphate, 0.1% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 30% of that of the powder A.
The embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder, portland cement clinker, sodium hydroxide and sodium aluminate according to the mixture ratio of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the powder A in the granulator to perform granulation to obtain aggregate; the running rotating speed of the ball mill is 10 r/min;
4) naturally stacking and curing the aggregate for 1 day, and then putting the aggregate into water at the temperature of 60 ℃ for curing for 7 days to obtain the phosphogypsum-based aggregate;
5) and (2) spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, spraying 300g of water-soluble organic silicon on each ton of the phosphogypsum-based aggregate, and naturally airing to obtain an aggregate finished product, wherein the purity of the water-soluble organic silicon is 100%, and the water-soluble organic silicon is diluted by adding water until the mass concentration is 50% for use.
Various performance indexes of the early-strength phosphogypsum-based artificial aggregate prepared by the embodiment can meet the national standard JTG E42-2005 road engineering aggregate test regulation and JTG E20-2011 road engineering asphalt and asphalt mixture test regulation. The aggregate had an apparent density of 2.765g/cm 3 Bulk density of the wool is 1.628g/cm 3 The water absorption was 2.9% and the crush value was 23.8%.
Example 3
The embodiment provides an early strength phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 50% of phosphogypsum, 15% of slag powder, 30% of coal ash powder, 4% of portland cement clinker, 0.5% of sodium hydroxide and 0.5% of sodium aluminate;
the solution B comprises 2% of sodium hexametaphosphate, 0.2% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 28 percent of that of the powder A.
The embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder, portland cement clinker, sodium hydroxide and sodium aluminate according to the mixture ratio of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the powder A in the granulator to perform granulation to obtain aggregate; the running rotating speed of the ball mill is 20 r/min;
4) naturally stacking and curing the aggregate for 2 days, and then putting the cured aggregate into normal-temperature water for curing for 14 days;
5) and spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, wherein 400g of water-soluble organic silicon is sprayed on each ton of the phosphogypsum-based aggregate, and the water-soluble organic silicon can be diluted by water to reach the mass concentration of 55%.
Various performance indexes of the early-strength phosphogypsum-based artificial aggregate prepared by the embodiment can meet the national standard JTG E42-2005 road engineering aggregate test regulation and JTG E20-2011 road engineering asphalt and asphalt mixture test regulation. The aggregate had an apparent density of 2.783g/cm 3 Bulk density of the wool 1.624g/cm 3 The water absorption was 2.4% and the crush value was 22.7%.
Example 4
The embodiment provides an early strength phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 50% of phosphogypsum, 45% of slag powder, 4% of silicate cement clinker, 1% of quicklime and 1% of sodium silicate;
the solution B comprises 1% of sodium hexametaphosphate, 0.1% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 28 percent of that of the powder A.
The embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder, portland cement clinker, quicklime and sodium silicate according to the proportion of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the powder A in the granulator to perform granulation to obtain aggregate; the running rotating speed of the ball mill is 10 r/min;
4) naturally stacking and curing the aggregate for 1 day, and then putting the cured aggregate into normal-temperature water for curing for 20 days;
5) and spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, wherein 500g of water-soluble organic silicon is sprayed on each ton of the phosphogypsum-based aggregate, and the water-soluble organic silicon can be diluted by water until the mass concentration of the water-soluble organic silicon is 60%.
Various performance indexes of the early-strength phosphogypsum-based artificial aggregate prepared by the embodiment can meet the national standard JTG E42-2005 road engineering aggregate test regulation and JTG E20-2011 road engineering asphalt and asphalt mixture test regulation. The aggregate had an apparent density of 2.723g/cm 3 Bulk density of 1.618g/cm 3 The water absorption was 2.1% and the crush value was 21.8%.
Example 5
The embodiment provides an early strength phosphogypsum-based aggregate which is prepared by mixing powder A and solution B into a ball; the powder A comprises the following components in percentage by mass: 60% of phosphogypsum, 37% of slag powder, 2% of silicate cement clinker, 0.5% of quicklime and 0.5% of sodium aluminate;
the solution B comprises 1.5 percent of sodium hexametaphosphate, 0.1 percent of cellulose ether and the balance of water by mass percent, and the total amount is 100 percent;
the mass of the solution B is 25% of that of the powder A.
The embodiment also provides a preparation method of the phosphogypsum-based aggregate, which comprises the following steps:
1) mixing phosphogypsum, slag powder, portland cement clinker, quick lime and sodium aluminate according to the mixture ratio of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the powder A in the granulator to perform granulation to obtain aggregate; the running rotating speed of the ball mill is 25 r/min;
4) naturally stacking and curing the aggregate for 1 day, and then putting the cured aggregate into water at 40 ℃ for curing for 14 days;
5) and spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate, wherein 300g of the water-soluble organic silicon is sprayed on each ton of the phosphogypsum-based aggregate, and the water-soluble organic silicon can be diluted by water until the mass concentration of the water-soluble organic silicon is 50%.
Various performance indexes of the early-strength phosphogypsum-based artificial aggregate prepared by the embodiment can meet the national standard JTG E42-2005 road engineering aggregate test regulation and JTG E20-2011 road engineering asphalt and asphalt mixture test regulation. The aggregate had an apparent density of 2.721g/cm 3 Bulk density of the wool of 1.614g/cm 3 The water absorption was 2.2% and the crush value was 23.2%.
Comparative example 1
The phosphogypsum aggregate of this comparative example differs from example 1 in that no alkali activator is added, all the others being the same.
The phosphogypsum-based aggregate prepared by the comparative example has the apparent density of 2.757g/cm 3 Bulk density of the wool of 1.614g/cm 3 The water absorption was 3.2% and the crush value was 42%. The reason why the crushing value of the comparative example was high may be that the curing time was short in the absence of the alkali-activator, which affected the strength of the aggregate.
Comparative example 2
The proportion of the phosphogypsum aggregate prepared by the comparative example is the same as that of the phosphogypsum aggregate prepared by the example 1, except that no water-soluble organic silicon is sprayed on the surface of the phosphogypsum aggregate prepared by the example.
The phosphogypsum-based aggregate prepared by the comparative example has the apparent density of 2.125g/cm 3 Bulk density of 1.104g/cm 3 The water absorption was 25% and the crush value was 22.5%. The reason why the aggregate prepared in this comparative example has a high water absorption rate is that the surface of the aggregate has no water-soluble silicone and lacks pore filling, resulting in more pores and easy water absorption.
Application example 1
The phosphogypsum-based aggregate prepared in example 1 (i.e., artificial aggregate described below) was used in an asphalt mix AC-13 grading design, in which the artificial aggregate replaced natural aggregate of 1.18mm to 16mm, and the artificial aggregate in the replaced mix accounted for 74% of the total volume of the mineral aggregate. The grading design data and curves are respectively shown in table 1 and fig. 2, the road performance test of the mixture is compared with the limestone natural aggregate, and the data is shown in table 2. Wherein the dynamic stability of the ruts is 1500 times/mm.
TABLE 1 artificial aggregate mixture gradation design
| Mesh size | 16 | 13.2 | 9.5 | 4.75 | 2.36 | 1.18 | 0.6 | 0.3 | 0.15 | 0.075 | Mixing ratio |
| Upper limit of grading | 100 | 100 | 85 | 68 | 50 | 38 | 28 | 20 | 15 | 8 | |
| Lower limit of grading | 100 | 90 | 68 | 38 | 24 | 15 | 10 | 7 | 5 | 4 | |
| Median grading of | 100 | 95 | 76.5 | 53 | 37 | 26.5 | 19 | 13.5 | 10 | 6 | |
| Artificial aggregate | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 5％ |
| Artificial aggregate | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 21％ |
| Artificial aggregate | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 23％ |
| Artificial aggregate | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 16％ |
| Artificial aggregate | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 10％ |
| Limestone | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 | 7％ |
| Limestone rock | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 0.0 | 6％ |
| Limestone | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 0.0 | 3％ |
| Limestone | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.0 | 4％ |
| Limestone | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 3％ |
| Mineral powder | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 99.2 | 94.6 | 3％ |
| Composition grading | 100.0 | 95.0 | 76.5 | 53.0 | 37.0 | 26.5 | 19.0 | 13.5 | 10.0 | 6.0 | 100％ |
TABLE 2 Performance test results of mixtures of limestone natural aggregates and artificial aggregates
As can be seen from Table 2, the phosphogypsum-based aggregate provided by the embodiment has higher stability than natural aggregate, and other properties meet the design requirements of the specification.
Application example 2
The artificial aggregate prepared in example 1 was used for a cement-stabilized base mix gradation design. Wherein, the artificial aggregate mainly replaces natural aggregate with the diameter of 4.75mm-31.5mm, and the artificial aggregate in the replaced mixture accounts for 65 percent of the total volume of the mineral aggregate. Wherein the aggregate accounts for 85 percent of the dry basis weight, the fly ash accounts for 15 percent of the dry basis weight, the cement consumption is 3 percent, and the maximum dry density is 2.271g/cm 3 The optimum water content is 7.5%. The grading design data and curves are shown in table 3 and fig. 3, respectively. The unconfined compressive strength of a 150mm cylindrical test piece molded by the gradation reaches 4.5MPa in 7 days, and the strength reaches 7.5MPa in 28 days.
TABLE 3 Water stability level configuration meter
| Mesh size | 31.5 | 26.5 | 19 | 9.5 | 4.75 | 2.36 | 0.6 | 0.075 | Mixing proportion |
| Upper limit of grading | 100 | 100 | 89 | 67 | 49 | 35 | 22 | 7 | |
| Lower limit of grading | 100 | 90 | 72 | 47 | 29 | 17 | 8 | 0 | |
| Median grading of | 100 | 95 | 80.5 | 57 | 39 | 26 | 15 | 3.5 | |
| |
100 | 79.6 | 10 | 0.6 | 0.5 | 0.5 | 0.5 | 0.5 | 15％ |
| |
100 | 100 | 100 | 46.8 | 7.5 | 1.0 | 0.6 | 0.6 | 50 |
| Limestone | |||||||||
| 100 | 100 | 100.0 | 100.0 | 97.9 | 73.7 | 32.2 | 1.4 | 35 | |
| Composition grading | |||||||||
| 100 | 96.9 | 86.5 | 58.5 | 38.1 | 26.4 | 11.6 | 0.9 | 100％ |
Other beneficial effects are as follows:
1. adding quicklime powder into phosphogypsum base to generate Ca (OH) of new ecology in the digestion process 2 The material has stronger activity, releases a large amount of heat simultaneously, can improve the temperature of a system, accelerates the velocity of the pozzolanic reaction and improves the early strength of the aggregate.
2. Because the aggregate is hydraulic aggregate, the inside hydration reaction that lasts of aggregate produces intensity after the maintenance shaping, and moisture in the external environment can promote the intensity increase of aggregate, consequently the storage process need not dry dampproofing dustproof, can store in the open air, and the natural sunning is dry before the aggregate uses can.
The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.
Claims (7)
1. The phosphogypsum-based aggregate is characterized by being prepared by mixing powder A and solution B into balls; the powder A comprises the following components in percentage by mass: 50-80% of phosphogypsum, 15-45% of waste residue powder, 3-6% of alkaline activator and 100% of the total;
the solution B comprises 1-2% of sodium hexametaphosphate, 0.1-0.2% of cellulose ether and the balance of water by mass percent, wherein the total amount is 100%;
the mass of the solution B is 25-30% of the mass of the powder A; the alkaline excitant is the combination of one or more of portland cement clinker, sodium hydroxide, sodium aluminate and sodium silicate and quick lime;
the preparation method of the phosphogypsum-based aggregate comprises the following steps:
1) mixing phosphogypsum, slag powder and an alkaline activator according to the proportion of the components to obtain powder A;
2) adding sodium hexametaphosphate and cellulose ether into water to dissolve to obtain a solution B;
3) putting the powder A prepared in the step 1) into a granulator, and continuously spraying the solution B into the granulator to be mixed with the powder A, and granulating to obtain an aggregate;
4) and (3) soaking and curing the aggregate after curing to obtain the phosphogypsum-based aggregate, and spraying water-soluble organic silicon on the surface of the phosphogypsum-based aggregate.
2. The phosphogypsum-based aggregate according to claim 1, characterized in that the waste slag powder is slag powder.
3. The phosphogypsum-based aggregate according to claim 1, characterized in that the waste slag powder is a mixture of slag powder and coal ash powder, comprising 5-15% of slag powder and 10-30% of coal ash powder.
4. The phosphogypsum-based aggregate according to claim 1, characterized in that in step 4) the soaking maintenance comprises: and putting the solidified aggregate into normal-temperature water for curing for 14-28 days.
5. The phosphogypsum-based aggregate according to claim 1, characterized in that in step 4) the soaking maintenance comprises: and putting the solidified aggregate into water with the temperature of 40-80 ℃ for curing for 7-14 days.
6. The phosphogypsum-based aggregate according to claim 1, characterized in that in step 4) the solidification of the aggregate comprises in particular: and naturally stacking and curing the aggregate for 1-2 days.
7. The phosphogypsum-based aggregate according to claim 1, characterized in that 300-600g of the water-soluble silicone is sprayed per ton of the phosphogypsum-based aggregate.
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