CN114180920A

CN114180920A - Preparation method of low-water-cement-ratio phosphogypsum light building block

Info

Publication number: CN114180920A
Application number: CN202111386576.2A
Authority: CN
Inventors: 谈云志; 王媛; 李辉; 吴军; 韩爽
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2022-03-15

Abstract

The invention provides a preparation method of a low-water-cement-ratio phosphogypsum light building block, which comprises the following steps: preparing ice particles according to the optimal mass ratio of water to ash; preparing phosphogypsum powder according to the mass of the ice particles, and uniformly mixing the phosphogypsum powder and the ice particles; pouring the mixture of the phosphogypsum powder and the ice particles into a mould, and compacting by a press; demoulding after the ice particles are melted and the phosphogypsum is initially solidified; the low-water-cement-ratio phosphogypsum light building block is obtained through the steps. The phosphogypsum block or bar can be prepared under the condition of optimal water content, the phosphogypsum is fully hydrated, the strength meets the requirement, and the problem of phosphogypsum cracking caused by excessive water is avoided. The hollow volume can be estimated through the quantity of the added ice particles, the hollow rate of the phosphogypsum building blocks or strips can be freely controlled, light products are prepared, the consumption of raw materials is reduced, and the phosphogypsum building block can be used for filling and insulating walls.

Description

Preparation method of low-water-cement-ratio phosphogypsum light building block

Technical Field

The invention relates to the field of novel building materials, in particular to a preparation method of a low-water-cement-ratio phosphogypsum light building block.

Background

With the prohibition of river sand mining and the limitation of machine-made sand, the contradiction between supply and demand of building wall materials is increasingly prominent. In order to break through the dilemma, it is necessary to find new material sources. The phosphogypsum slag is an industrial byproduct left by producing phosphate fertilizer and phosphoric acid from phosphate ore, and the main component of the phosphogypsum slag is calcium sulfate dihydrate. The resource utilization rate of the phosphogypsum is low, so that the stockpiling quantity of the phosphogypsum is increased day by day, a large amount of land is occupied, and the risk of environmental pollution is formed. In order to relieve the stockpiling pressure, promote the healthy development of the phosphorus chemical industry and accelerate the elimination of the phosphogypsum waste slag. The phosphogypsum slag becomes calcium sulfate hemihydrate, hereinafter referred to as phosphogypsum, after low-temperature calcination, and has the same gelling capacity as natural gypsum. When the phosphogypsum is hydrated, needle-shaped calcium sulfate crystals are gradually formed, and the crystals are mutually overlapped and rapidly combined into a net structure, so that the phosphogypsum is hardened. The hydration initial setting time of the phosphogypsum is completed within 2-5 min, the final setting is completed within 30min, and the strength can reach 95 percent of the highest strength during the final setting.

For this purpose, phosphogypsum is used for the production of building material products, such as: building blocks, battens and the like are gradually favored by the market, and a window is opened for the comprehensive utilization of the phosphogypsum. However, in the current preparation of phosphogypsum blocks or strips, the higher water-cement ratio is required to improve the fluidity of slurry, and the dry volume weight is expected to be reduced. In fact, the water requirement for phosphogypsum hydration gelling is much lower than the preparation water content, which means that most of the water is superfluous, but the preparation process must be carried out with an excessive amount of water. The main problems with excess moisture are:

1. increasing the temporary deadweight. Because the gypsum has compact structure after hydration, free water in the block is difficult to evaporate and escape, and the self weight of the building material product is larger in a longer time. And the excessive moisture also easily causes cracking or strength reduction of the finished phosphogypsum product.

2. The drying time is prolonged. The ardealite building material product is not fully dried, and the self weight is larger, so that the transportation cost is high; since the cost is rapidly increased by heat drying, it is only necessary to naturally dry the film for a prolonged period of time.

3. Enlarging the airing field. The water evaporation of the phosphogypsum building material products is accelerated, so the products cannot be stacked, the products must be spread out, the evaporation surface is enlarged as much as possible, and therefore, the airing field needs to be enlarged, and the time is required to be changed.

How to treat redundant moisture becomes a key technical problem of solving the problems of phosphogypsum building blocks and bar blocks, and the currently proposed method mainly comprises the following steps:

1. and (6) naturally airing. The phosphogypsum building material product is exposed in the atmosphere, the water evaporation is accelerated by means of natural wind and sunlight, but the phosphogypsum is very compact after hydration, the surface layer is easy to dry, the internal water is sealed and difficult to escape, so that the phosphogypsum building material product needs a long time and can reach the factory standard in about 2 months.

2. And (5) concentrated baking. The ardealite building material product is placed in a closed space, central heat supply is performed through modes of electricity burning, coal burning, gas burning and the like, and the water evaporation of the ardealite building material product is accelerated.

3. And (4) adding an auxiliary agent. The water-cement ratio is properly reduced, the auxiliary agent is added, the workability of the gypsum slurry is improved, but the water reducing amount is very limited, and the product is still in an ultra-wet state. It can be seen that the traditional high water-cement ratio mixing method has the defects that the hydration of the phosphogypsum is sufficient and the water-cement ratio cannot be too high, which is difficult to overcome. Therefore, a brand new path must be found to realize that the phosphogypsum preparation building blocks (strips) are not only dried quickly, but also have light dead weight.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a low-water-cement-ratio phosphogypsum light building block, which can accurately control the water-cement ratio of phosphogypsum and has strength meeting requirements. And the weight and the hollow rate of the phosphogypsum building block can be adjusted, and the phosphogypsum building block can be used for filling and insulating heat of a wall body.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a preparation method of a low-water-cement-ratio phosphogypsum light building block comprises the following steps:

s1, preparing ice particles according to the optimal water-ash mass ratio;

s2, preparing phosphogypsum powder according to the mass of the ice particles, and uniformly mixing the phosphogypsum powder and the ice particles;

s3, pouring the mixture of the phosphogypsum powder and the ice particles into a mould, and compacting by a press;

s4, demolding after the ardealite is initially solidified after the ice particles are melted;

the low-water-cement-ratio phosphogypsum light building block is obtained through the steps.

In a preferable scheme, the particle size of the ice particles is 0.75 cm-2.00 cm.

In the preferred scheme, the water for preparing the ice particles contains 0.3-1.0 mass percent of an accelerator.

In a preferred embodiment, the accelerator comprises K₂SO₄。

In the preferred scheme, the optimal water-cement mass ratio of the phosphogypsum powder is as follows: the ice particles are 28-45: 100.

in a preferred embodiment, the phosphogypsum powder: the ice particles are mixed for less than 30 seconds.

In the preferred scheme, the ice particles are prepared by adopting two layers of buckled silica gel plate moulds, the silica gel plate moulds are provided with grooves, the two silica gel plate moulds are mutually buckled and connected, and each groove is provided with a hole for water inlet.

In the preferred scheme, the ice particles are prepared by adopting a mould ice roller device, the mould ice roller device has the structure that a silica gel layer is arranged on the surface of the mould ice roller, and a refrigerant with the temperature lower than minus 20 ℃ is filled in the mould ice roller;

the silica gel conveying belt is arranged below the mold ice roller and is in contact with the mold ice roller, a plurality of forming grooves are formed in the surfaces of the silica gel conveying belt and the silica gel layer, the forming grooves in the silica gel conveying belt and the silica gel layer are in one-to-one correspondence, and a water supply pipe used for supplying water to the forming grooves is arranged on the upstream of the contact position of the silica gel conveying belt and the mold ice roller.

In a preferred scheme, the structure of the mold is as follows: the lower external mold is arranged on the bottom mold, a plurality of detachable internal molds are arranged on the inner wall of the lower external mold, and the upper mold is in sliding fit with the inner wall of the detachable internal molds.

In a preferred scheme, in step s4, the detachable inner mold is taken out after the phosphogypsum is initially set, then cement paste or phosphogypsum paste is poured into the lower outer mold to form a shell, and the whole building block is taken out after the initial set.

The invention provides a preparation method of a low water-cement ratio phosphogypsum light building block, and by adopting the scheme, compared with the prior art, the building block has the following beneficial effects:

1. the phosphogypsum block or bar can be prepared under the condition of optimal water content, the phosphogypsum is fully hydrated, the strength meets the requirement, and the problem of phosphogypsum cracking caused by excessive water is avoided.

2. The hollow volume can be estimated through the quantity of the added ice particles, the hollow rate of the phosphogypsum building blocks or strips can be freely controlled, light products are prepared, the consumption of raw materials is reduced, and the phosphogypsum building block can be used for filling and insulating walls.

3. The method can convert large holes in the traditional phosphogypsum building blocks or strips into small holes which are uniformly distributed, solves the problems of stress concentration and the like which possibly occur during the loading action, and improves the strength of the finished product.

4. The drying time of the phosphogypsum building blocks or strips can be greatly shortened, so that the turnover efficiency of an airing field is improved, and the annual production capacity of products is improved.

5. The mould ice roller equipment that sets up can improve the production efficiency of customization ice particle by a wide margin.

6. By adopting the structure of the detachable internal mold, the building block in the mold can form an attractive shell, and the appearance of cavities in the outer wall is prevented from affecting the attractiveness.

Drawings

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

FIG. 1 is a process flow diagram of the present invention.

Fig. 2 is a schematic structural diagram of a silica gel plate mold of the present invention.

FIG. 3 is a schematic structural view of a mold ice roller of the present invention.

Fig. 4 is a schematic structural view of the die pressing machine of the present invention.

Fig. 5 is a schematic view of a die pressing machine according to another preferred structure of the present invention.

Fig. 6 is a top view of a mold of a preferred construction of the invention.

Figure 7 is a flow chart of the hydration state of the phosphogypsum block of the invention.

Fig. 8 is a schematic view of the internal structure of the phosphogypsum block of the invention.

In the figure: the mould ice roller 1, silica gel layer 2, refrigerant 3, delivery pipe 4, silica gel conveyer belt 5, silica gel plate mould 6, press 7, go up mould 8, building block 9, lower external mold 10, removable lower internal mold 11, die block 12, shaping recess 13, doctor-bar 14.

Detailed Description

Example 1:

as shown in fig. 1, a preparation method of a low water-ash ratio phosphogypsum light building block comprises the following steps:

s1, preparing ice particles according to the optimal water-ash mass ratio;

in a preferable scheme, the particle size of the ice particles is 0.75 cm-2.00 cm. In a further preferred embodiment, the ice particles are graded ice particles, for example, 0.75cm, 1cm, 1.5cm, and 2cm account for 25% by mass, and ice particles with different particle sizes may be mixed according to other grading proportions and requirements of the final product for later use.

In a preferred embodiment, the accelerator comprises K₂SO₄。

An optional scheme is as shown in fig. 2, two layers of buckled silica gel plate molds 6 are adopted to prepare ice particles, grooves are formed in the silica gel plate molds 6, the two silica gel plate molds 6 are mutually buckled and connected, and each groove is provided with a hole for water inlet. Preferably, the mutually buckled grooves form a spherical shape. The scheme has low cost and is used for preparing ice particles in small batches.

Another alternative scheme is as shown in fig. 3, ice particles are prepared by adopting a mold ice roller device, the mold ice roller device has a structure that a silica gel layer 2 is arranged on the surface of a mold ice roller 1, and a refrigerant 3 with the temperature lower than-20 ℃ is filled in the mold ice roller 1; the preferred refrigerant 3 is liquid carbon dioxide or liquid nitrogen.

The silica gel conveying belt 5 contacted with the mold ice roller 1 is arranged below the mold ice roller 1, a plurality of forming grooves 13 are formed in the surfaces of the silica gel conveying belt 5 and the silica gel layer 2, the forming grooves 13 on the silica gel conveying belt 5 and the silica gel layer 2 are in one-to-one correspondence, and a water supply pipe 4 used for supplying water to the forming grooves 13 is arranged on the upstream of the contact position of the silica gel conveying belt 5 and the mold ice roller 1. The water supply pipe 4 continuously supplies water to the gap between the silica gel conveying belt 5 and the mold ice roller 1 by a preset amount, and when the silica gel conveying belt 5 and the molding groove 13 of the mold ice roller 1 are contacted with each other, the water is condensed into ice in the molding groove 13 which is buckled.

s3, as shown in figure 4, pouring the mixture of the phosphogypsum powder and the ice particles into a mould, and compacting by a press;

in a preferred embodiment as shown in fig. 5 and 6, the mold has the following structure: the lower outer die 10 is arranged on the bottom die 12, a plurality of detachable lower inner dies 11 are arranged on the inner wall of the lower outer die 10, and the upper die 8 is in sliding fit with the inner wall of the detachable lower inner dies 11. The scheme of adopting the ice particles also creates a new problem, the outer wall of the building block 9 is easy to generate a cavity because the ice particles are tightly attached to the inner wall of the mould, and the defect is overcome by adopting the structure of the detachable inner mould 11. As shown in fig. 6, the preferred removable inner mold 11 is divided into 4 pieces, one on each side, with a lifting lug at the top end of each piece of removable inner mold 11 for pulling. Each detachable inner die 11 is provided with a draft angle of 3 degrees.

in a preferable scheme, in step s4, after the phosphogypsum is initially set, the detachable inner die 11 is taken out, then cement paste or phosphogypsum paste is poured into the lower outer die 10 to form a shell, and after the initial set, the whole building block 9 is taken out. It is preferable that

The waterproof cement paste, such as polymer cement paste, can prevent the outer wall of the building block 9 from cracking and form a waterproof protective layer on the outer wall of the building block 9.

The low-water-cement-ratio phosphogypsum light building block 9 is obtained through the steps.

Example 2:

on the basis of the embodiment 1, the low water-ash ratio phosphogypsum light building block or bar is prepared by tap water into ice particles, preferably round, the mass of the ice particles is equal to that of liquid water, and the diameter of the ice particles is 1.0 cm. According to the optimal water-cement ratio, namely the ratio of the mass of water to the mass of the dry phosphogypsum powder, ice particles and the phosphogypsum powder are quickly and uniformly mixed, and then according to the preset dry density, the dry density is 0.7-1.0 g/cm³Pouring the mixture of the ice particles and the phosphogypsum powder which are accurately measured into a mould, and compacting the mixture to a preset volume by using a press machine 7; and (4) after the ice is melted, demolding after the building block or the bar block is initially set. As shown in fig. 8, the phosphogypsum filled with ice particles can keep a cavity, and the hollow rate of the building block is calculated by controlling the number of the ice particles.

The setting accelerator with the mass ratio of 0.5% is adopted, can improve the condensation speed of the phosphogypsum, accelerate the solidification of the phosphogypsum around ice particles, delay the melting speed of the ice particles and facilitate the formation of cavities, and the water cement ratio is preferably 30: when the weight of the phosphogypsum is 100 hours, the phosphogypsum can be fully hydrated, the self weight can be reduced, and the phosphogypsum around the phosphogypsum can be fully hydrated by utilizing the uniform distribution of ice particles; the ratio of water to ash and the degree of compaction are adjusted, the mass ratio of ice is converted into the volume ratio, and the hollow rate can be freely controlled.

The mixing process of the ice particles and the phosphogypsum powder is completed within 30 seconds, and the die-reversing, compacting and forming are completed within 2 minutes. The ice particles and the phosphogypsum powder can be bonded outside the ice particles by mixing, and the shorter the time is, the slower the melting rate of the ice particles is.

The geometric dimension of the building block or the bar is determined according to the application unified technical specification of the phosphogypsum building material DBJ 52/T093-2019. The strength of the block or bar in this example after complete drying was tested to be 5.1 MPa. Meet the performance requirements of DBJ52/T093-2019 phosphogypsum building material application unified technical specification. The range of the press is 0-10T, and the loading speed can be controlled.

The method comprises the following specific steps:

1. and preparing ice particles. The silica gel plate die 6 can prepare ice particles of four sizes, the diameters of which are 0.75cm, 1.0 cm, 1.5cm and 2.0 cm respectively. Selecting a silica gel plate mold 6 with the diameter of 1.0 cm to produce ice particles, mixing the ice particles with all sizes, and storing the ice particles in a cold storage area.

2. Homogenizing the phosphogypsum. Before the phosphogypsum powder enters the bin, the phosphogypsum powder is fully and uniformly mixed.

3. Mixing the ice particles with the phosphogypsum powder. According to the production capacity of each time, the dosage of the phosphogypsum and the dosage of the ice particles are respectively measured, and the phosphogypsum and the ice particles are poured into a mixing bin to be stirred for 15 to 20 seconds.

4. And filling the ice particles and the phosphogypsum powder into a mold. And (3) feeding the mixed ice particles and the phosphogypsum powder into a mould as shown in the figure 4 according to the metering, scraping the mixture above the mould, and finishing within 60-70 seconds.

5. And (5) compacting and forming. And (3) compacting the mixture of the ice particles and the phosphogypsum powder in the block mould to a preset volume by using pressure equipment according to the preset dry density of the block or the bar, and finishing within 20-30 seconds.

6. And (5) shaping the mould and waiting for coagulation. And integrally moving out the mold loaded with the building blocks or the bar blocks, placing the mold in a to-be-condensed area for 20-25 minutes, and waiting until ice particles are fully melted and the phosphogypsum is basically finally condensed.

7. And (5) demolding and maintaining. And (4) removing the building blocks or the strips in the mold, and then transferring the building blocks or the strips to a maintenance area for inspection and delivery.

Through the steps, the low-water-cement-ratio phosphogypsum light building block or bar is obtained. The hollow rate of the low-water-ash-ratio phosphogypsum light building block or bar block obtained in the embodiment is 23-43%. The water content is 28-42%.

Example 3:

1. adding 50kg of tap water, adding 250g of accelerating agent, dissolving and stirring uniformly, pouring into a silica gel mold with the size of 1.5cm, and placing in a freezing area.

2. After ice particles are frozen and formed, a machine is used for demoulding, and 50kg of ice particles and 150kg of phosphogypsum are weighed according to the water-cement ratio of 33: 100, pouring the mixture into a mixing bin, and stirring for 15-20 seconds.

3. After being mixed uniformly, the mixture is fed into a plurality of moulds, and the length, width and height of the interior of each mould are 600mm multiplied by 500mm multiplied by 200 mm.

4. The preset dry density of the building block 9 is 0.7g/cm³Compacting the mixture in the block bar mold to a predetermined volume, respectively 60000cm, using a press³And finishing within 20-30 seconds.

5. And moving the whole mould loaded with the building blocks out, placing the mould in a to-be-solidified area for 20-25 minutes, and waiting for the ice particles to be fully melted and the final solidification of the phosphogypsum to be finished.

6. And (5) demolding and maintaining. And (4) stripping the building block strip in the mold, and then transferring the building block strip to a maintenance area for inspection and delivery.

The hollow rate of the low-water-ash-ratio phosphogypsum light building block bar prepared in the embodiment is 23.9%, and the water content is 30%. If the traditional method is used, under the same hollow rate, the water content of the obtained phosphogypsum light building block bar is 65%.

Example 4:

1. 200kg of tap water is added, 250g of accelerating agent is added, the mixture is dissolved and stirred uniformly, ice particles are prepared by using a mold ice roller 1, and the efficiency is greatly improved compared with that of a silica gel plate mold 6. In practice, 180kg of ice particles are obtained.

2. Weighing 16.8kg of ice particles and homogenized 42.0kg of phosphogypsum according to a water-cement ratio of 40: 100, pouring the mixture into a mixing bin, and stirring for 15-20 seconds.

3. And (3) feeding 58.8kg of the mixed ice particles and phosphogypsum powder into a die shown in the figure 5, wherein the length, the width and the height of the interior of the die are 580mm multiplied by 480mm multiplied by 200mm, the area of a first upper die is 580mm multiplied by 480mm, and the thickness of a detachable inner die 11 is 10 mm.

4. The preset dry density of the building block is 0.7g/cm³Compacting the mixture of ice particles and phosphogypsum powder in the block mould to a predetermined volume of about 60000cm by a press 7³And is finished within 20-30 seconds.

5. And moving the mold loaded with the building blocks out integrally, placing the mold in a to-be-coagulated area for 20-25 minutes, taking out the detachable inner mold 11 when ice particles are fully melted and phosphogypsum is basically finally coagulated, and continuously pouring polymer cement slurry in the mold, wherein polymer cement waterproof mortar is preferably adopted. Preferably, pressing is continued with a second upper die press having an area of 600mm by 500 mm. Or directly curing and demoulding.

6. And (5) demolding and maintaining. And (4) removing the building blocks in the mold, and then transferring the building blocks to a maintenance area for inspection and delivery.

The low-cement-ratio phosphogypsum light building block prepared in the embodiment has the advantages of hollow rate of 41.5%, water content of 40%, no holes in appearance, attractive shape, hydrophobic surface and good waterproof effect. If the traditional method is used, under the same hollow rate, the water content of the obtained phosphogypsum light building block bar is 65%.

The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and features in the embodiments and examples in the present application may be arbitrarily combined with each other without conflict. The protection scope of the present invention is defined by the claims, and includes equivalents of technical features of the claims. I.e., equivalent alterations and modifications within the scope hereof, are also intended to be within the scope of the invention.

Claims

1. a preparation method of low water-cement ratio phosphogypsum lightweight building block, is characterized in that comprising the following steps:

s1. Prepare ice particles according to the optimal water-cement mass ratio;

s2. According to the quality of ice particles and prepare phosphogypsum powder, mix phosphogypsum powder and ice particles evenly;

s3. Pour the mixture of phosphogypsum powder and ice particles into the mold, and compact it with a press;

s4. After the ice particles are melted, the phosphogypsum is initially set and then demoulded;

Through the above steps, a low water-cement ratio phosphogypsum lightweight building block (9) is obtained.

2. the preparation method of a kind of low water-cement ratio phosphogypsum lightweight building block according to claim 1, is characterized in that: the particle diameter of ice particle is 0.75cm～2.00cm.

3. the preparation method of a kind of low water-cement ratio phosphogypsum light block according to claim 1, is characterized in that: the water that prepares ice grains has the quick-setting agent of mass ratio 0.3%～1.0%.

4. The preparation method of a low water-cement ratio phosphogypsum lightweight block according to claim 3, characterized in that: the quick-setting agent comprises K ₂ SO ₄ .

5. The preparation method of a low water-cement ratio phosphogypsum light block according to claim 1, characterized in that: the optimal water-cement mass ratio of phosphogypsum powder: ice particles is 28-45:100.

6. The preparation method of a low water-cement ratio phosphogypsum lightweight block according to claim 1, wherein the mixing time of the phosphogypsum powder and the ice particles is less than 30 seconds.

7. The preparation method of a kind of low water-cement ratio phosphogypsum lightweight building block according to claim 1, it is characterized in that: adopt the silica gel plate mould (6) of two layers to buckle to prepare ice particles, the silica gel plate mould (6) ) is provided with grooves, the two silica gel plate molds (6) are fastened and connected to each other, and each groove is provided with an opening for water intake.

8. the preparation method of a kind of low water-cement ratio phosphogypsum light block according to claim 1, it is characterized in that: adopt mould ice roller device to prepare ice grain, the structure of mould ice roller device is, mould ice roller ( 1) The surface is provided with a silica gel layer (2), and the mold ice roller (1) is filled with a refrigerant (3) with a temperature lower than -20°C;

A silicone conveyor belt (5) in contact with the mold ice roller (1) is provided below the mold ice roller (1), and a plurality of forming grooves (13) are provided on the surfaces of the silicone conveyor belt (5) and the silicone layer (2). ), the silicone conveyor belt (5) and the molding grooves (13) on the silicone layer (2) are in one-to-one correspondence, and upstream of the contact position between the silicone conveyor belt (5) and the mold ice roller (1) is provided with forming grooves (13). A water supply pipe (4) for water supply to the tank (13).

9. The preparation method of a low water-cement ratio phosphogypsum lightweight block according to claim 1, characterized in that: the structure of the mold is: the lower outer mold (10) is arranged on the bottom mold (12), A plurality of removable inner molds (11) are arranged on the inner wall of the lower outer mold (10), and the upper mold (8) is slidably matched with the inner wall of the removable inner mold (11).

10. The preparation method of a low-water-cement ratio phosphogypsum lightweight block according to claim 9, characterized in that: in step s4, after the initial setting of the phosphogypsum, the removable inner mold (11) is first taken out, and then Cement slurry or phosphogypsum slurry is poured into the lower outer mold (10) to form a shell, and after initial setting, the entire block (9) is taken out.