CN113461397B

CN113461397B - Semi-dry production method for preparing phosphogypsum building block in mechanized and continuous mode and phosphogypsum building block

Info

Publication number: CN113461397B
Application number: CN202110548212.3A
Authority: CN
Inventors: 封信超; 陈正强
Original assignee: Zunyi Hanfeng Decoration Material Co ltd
Current assignee: Zunyi Hanfeng Decoration Material Co ltd
Priority date: 2021-01-26
Filing date: 2021-05-19
Publication date: 2022-04-15
Anticipated expiration: 2041-05-19
Also published as: CN112745097A; CN113461397A

Abstract

The invention discloses a semi-dry production method for mechanically and continuously preparing phosphogypsum building blocks, which comprises the following steps: firstly, preparing 100 parts of fried phosphogypsum powder, 25-30 parts of water and a proper amount of auxiliary agent according to the weight part ratio; secondly, adding the raw materials in proportion, and uniformly mixing and stirring for 70-100 seconds; then pouring the mixture into a forming machine, pressing the mixture into a shape with the pressure of 180 tons and the pressure of 18-23 MPa for 20-30 seconds, and ejecting out the building blocks after the pressing is finished; and finally, placing the pressed building block for 15-30 minutes and warehousing or leaving the factory. The invention also discloses the phosphogypsum building block. The production method can reduce the water consumption and the press forming time, improve the maintenance temperature of the building block by using the heat of hydration reaction, does not need to be dried, can be hoisted and transported to be put in storage or leave factory within 15-30 minutes, obviously increases the strength of the phosphogypsum building block, saves the production cost, improves the production efficiency and ensures the qualified rate of products.

Description

Semi-dry production method for preparing phosphogypsum building block in mechanized and continuous mode and phosphogypsum building block

Technical Field

The invention belongs to the technical field of phosphogypsum chemical building materials, and particularly relates to a semi-dry production method for preparing a phosphogypsum block by adopting full-process mechanized continuous high efficiency and the phosphogypsum block.

Background

By-product phosphogypsum (the main component is CaSO) discharged by high-temperature calcination wet-process phosphoric acid production₄·2H₂O) production of fried phosphogypsum powder (the main component is CaSO)₄·1/2H₂O, original P of phosphogypsum₂O₅、SiO₂、Al₂O₃、Fe₂O₃MgO, F and other impurities are greatly reduced due to high-temperature burning loss, and the burning loss rateAround 14%) is a cement-like cement-friendly cementitious material, since hemihydrate gypsum (CaSO)₄·1/2H₂O) dihydrate Gypsum (CaSO) produced in the presence of Water₄·2H₂And the crystals (crystal water) of O) are mutually linked, so that the strength of the phosphogypsum-like block is developed and developed. Therefore, the adoption of the fried phosphogypsum (powder) to manufacture the phosphogypsum building block becomes one of the important approaches for quickly and environmentally utilizing the phosphogypsum at home and abroad.

The fried phosphogypsum has two important chemical properties: firstly, the gypsum dehydrates to form dihydrate gypsum (CaSO) when meeting water₄·2H₂O) and develops the strength of the block-like mass due to the inter-linkage between the dihydrate gypsum crystal waters. Therefore, the method for producing the phosphogypsum building blocks by using the fried phosphogypsum powder by adopting a pure dry method (namely, no water is added) is not feasible, the phosphogypsum building blocks need to be subjected to hydration reaction and develop the strength of the product in the production process of the product, and the building blocks which are forcibly formed by adopting the dry method can be subjected to hydration reaction when meeting water in the use process and inevitably cause the deformation of a building. Secondly, the fried phosphogypsum with the same quality has stable initial setting time (hydration reaction begins to occur to form crystal water) and final setting time (the hydration reaction stops, the crystal water is not formed any more), the initial setting time is 3-8 minutes generally, and the final setting time is 7-17 minutes. The block sample block at the beginning of initial setting has strength, and the strength of the block sample block is gradually developed along with gradual completion and proper maintenance of final setting.

The phosphogypsum building block produced at home and abroad is produced by manually pouring a flat mould at first, is produced by mechanically pouring and molding a vertical mould by jacking at present, utilizes the two chemical characteristics of fried phosphogypsum, and is called as a wet method because the water consumption generally reaches over 90 percent of the consumption of fried phosphogypsum powder in order to realize uniform stirring and pouring molding. The vertical die jacking mechanized casting molding production adopts the principle of stirring, pouring, molding and jacking and demolding, the stirring time of the slurry of the original auxiliary material (raw material and auxiliary material) is about 50 seconds generally, the slurry is poured into a die cavity, standing is needed in the die cavity until the slurry is hydrated for initial setting to form certain strength, jacking and demolding can be carried out, a clamp is used for clamping and conveying the phosphogypsum building block to a product drying yard for airing or drying on a drying line for drying after final setting, the process generally takes 7-8 minutes, the water content of the phosphogypsum building block sample block reaches more than 70%, the production efficiency is low, and the time for airing is long.

The semi-dry method for preparing the phosphogypsum building block is a new technology appearing in recent years, and the weight ratio of the used raw materials of the gypsum powder to water is about 1: 20% -30%, can reduce the production cycle of the phosphogypsum building block greatly, press forming only needs 3-5 minutes after mixing, the gypsum building block formed has low water content, the airing or oven drying can leave the factory for several hours, for example: chinese patent 'a semidry process high-strength gypsum product and its production method (publication No. CN 109400094A)'.

Although the traditional production period is greatly shortened by the existing technique for preparing the phosphogypsum building block by the semidry method, the press forming process still needs 3-5 minutes, the production efficiency is still restricted, continuous production cannot be carried out, and auxiliary drying is still needed after forming, so that the efficiency of the whole production line is reduced, and the production cost is increased.

Disclosure of Invention

The invention aims to overcome the problems in the background technology and provide a semi-dry production method for mechanically and continuously preparing the phosphogypsum block, so that the strength of the phosphogypsum block is increased, the production efficiency of the phosphogypsum block is improved, the production cost is reduced, and the qualification rate of the product is ensured.

In order to achieve the purpose, the invention adopts the technical scheme that: the semi-dry production method for preparing the phosphogypsum building block in a mechanized and continuous mode comprises the following steps:

1) preparing materials: preparing 100 parts of fried phosphogypsum powder, 25-30 parts of water and a proper amount of auxiliary agent according to the weight part ratio;

2) mixing materials: adding the raw materials in proportion, uniformly mixing and stirring for 70-100 seconds;

3) and (3) pressing and forming: pouring the mixture into a forming machine, pressing the mixture into a shape with the pressure of 180 tons and the pressure of 18-23 MPa for 20-30 seconds, and ejecting the building blocks after the pressing is finished;

4) forming and maintaining: and (4) placing the pressed building blocks for 15-30 minutes and warehousing or leaving the factory.

Further, in the step of preparing materials, the auxiliary agent comprises 0.01-0.3 part of macromolecule water-retaining agent.

Furthermore, the water absorption of the polymer water retention agent is 100-1000 times of the self weight, and the fineness of the polymer water retention agent is 20-120 meshes.

Still further, the polymer water-retaining agent is resin.

Furthermore, the auxiliary agent also comprises a water reducing agent, a dispersing agent, a retarder and a reinforcing agent, wherein the water reducing agent is 0.01 to 0.1 part, the dispersing agent is 0.01 to 0.1 part, the retarder is 0.01 to 0.1 part, and the reinforcing agent is 0.02 to 0.2 part.

Further, in the material mixing step, firstly, a water reducing agent, a water-retaining agent and a dispersing agent are sequentially mixed with water to form mixed water; secondly, adding a retarder and a reinforcing agent into the fried phosphogypsum powder to form a phosphogypsum powder mixture; and then pouring the mixed water into the phosphogypsum powder mixture for fully stirring to form a mixed material.

Furthermore, in the step of press forming, the upper press head presses downwards with 180 tons of pressure, then the lower press head presses upwards with 230 tons of pressure, after the size of the building block is reached, the building block is kept static for pressing for 3 seconds, and finally the building block is ejected out.

Further, in the forming and maintaining step, the pressed building blocks are placed in a factory building, and steam collecting covers are arranged around and above the building blocks.

The invention has the beneficial effects that: the semi-dry production method for mechanically and continuously preparing the phosphogypsum building block is not only suitable for producing the gypsum building block by utilizing natural gypsum, but also suitable for producing the gypsum building block by utilizing desulfurized gypsum or other industrial by-product gypsum. Compared with the traditional manual production of flat plate moulds and the existing mechanized production method of hydraulic jacking of vertical moulds, the method has the following advantages:

1. the water consumption can be obviously reduced by controlling the proportion of the fried phosphogypsum powder to the water consumption, the water consumption of the method is only 25-30% of that of the fried phosphogypsum powder, the water consumption is reduced by 60-65% compared with the water consumption of the traditional manual pouring production of a flat plate mould and the mechanized production method of hydraulic jacking of a vertical mould, the water consumption is reduced, the water resource can be saved, the production cost is reduced, and the production efficiency is improved.

2. According to the invention, the high-molecular water-retaining agent is added, and is mixed with water, and then stirred with the fried phosphogypsum powder, so that the free water content of the pressed and formed phosphogypsum block is obviously reduced and is easy to stir uniformly, the demolding strength of the block is obviously increased, the high-molecular water-retaining agent can continuously provide water required by the hydration reaction of the phosphogypsum powder after pressing and demolding, the final setting strength of the block is ensured, the hydration is uniform and sufficient, and the qualification rate of quickly producing the phosphogypsum block is greatly improved.

3. According to the invention, by accurately controlling the pressing technical parameters, the pressing time is shortened to 20-30 seconds, the pressing time is shortened by more than 14 times compared with the forming time of 7-8 minutes of the vertical die hydraulic jacking mechanical production, and the forming time is shortened by more than 5 times compared with the forming time of 3-5 minutes of the existing semi-dry method technology, so that the efficiency of mechanically and continuously preparing the phosphogypsum building block is obviously improved.

4. In the building block forming and curing stage, the heat release of the hydration reaction is fully utilized, the steam collection cover is utilized to steam and protect the building block, the temperature of the building block is increased by about 5-10 ℃, the final setting reaction speed of the building block is accelerated, drying is not needed, the building block can be directly hoisted and transported to be put in storage or leave a factory within 15-30 minutes, the production cost is reduced, and the production efficiency is improved.

5. The phosphogypsum building block produced by high-pressure forming and low water-cement ratio is in a porous hollow shape, has high strength, the compressive strength is more than 4 MPa, the fracture load is more than 9000N, and the softening coefficient is more than 0.8, thereby greatly improving the quality of the gypsum building block.

The invention also provides the phosphogypsum building block which comprises 100 parts of fried phosphogypsum powder, 25-30 parts of water and a proper amount of auxiliary agent, wherein the auxiliary agent comprises 0.01-0.3 part of high-molecular water-retaining agent.

Furthermore, the water absorption of the polymer water retention agent is 1000 times of the self weight, the fineness of the polymer water retention agent is 20-120 meshes, and the polymer water retention agent is resin.

The beneficial technical effects of the phosphogypsum building block are the same as those of the method disclosed by the invention, and the detailed description is omitted.

Detailed Description

The technical solution of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention. The described embodiments are only some, not all embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The application enjoys the prior application in China, the application number is 202110104322.0 and the name of the invention is: priority of a semi-dry production method for mechanically and continuously preparing phosphogypsum building blocks.

The initial setting of the fried phosphogypsum powder is related to water absorption, and the hydration reaction is an exothermic reaction. The initial setting water absorption rate is 18-19% of the weight of the fried phosphogypsum powder (which is the basic water amount required for forming crystal water by the whole hydration), and the hydration reaction is accelerated and releases certain heat with the increase of the water absorption rate.

The material ratio and the compression molding parameters of the phosphogypsum building block are closely related to the mold stripping strength, the water content and the subsequent hydration reaction speed of the phosphogypsum building block. Repeated tests show that under the molding conditions of the pressure of 180-230 tons and the pressure of 18-23 MPa, when the water absorption rate reaches 25-30% of the weight of the fried phosphogypsum, the hydration reaction speed is remarkably accelerated, and the heat release is remarkably increased.

As the water consumption of the prior production process reaches about 90 percent, the exothermic heat of the reaction can not obviously raise the temperature of the building block, so that people almost ignore the exothermic reaction phenomenon. When the water consumption is reduced, the exothermic heat of the reaction can obviously raise the temperature of the building block, the building block can be obviously felt by touching with hands, and the gypsum sample block can emit a large amount of water vapor, and the surface temperature can reach more than 45 ℃ (the temperature of a pressing forming cavity is about 40 ℃).

Example 1

A semi-dry production method for preparing phosphogypsum building blocks in a mechanized and continuous manner comprises the following steps:

1) preparing materials: preparing 100 parts of fried phosphogypsum powder, 25-30 parts of water and a proper amount of auxiliary agent according to the weight part ratio. The auxiliary agents comprise a polymer water-retaining agent, a water reducing agent, a dispersing agent, a retarder and a reinforcing agent. Wherein, the macromolecular water retention agent is 0.01 to 0.3 portion. The macromolecule water-retaining agent, SAP for short, can absorb water which is much more than the self weight, has the water absorption rate of 100-1000 times of the self weight, and has strong water-retaining capacity, so the macromolecule water-retaining agent is also called super water-retaining agent or high water-retaining agent. The polymer water-retaining agent includes starch type, cellulose type and resin type, and specifically includes polyacrylate, acrylic acid copolymer, polyvinyl alcohol type, and the like. The fineness of the macromolecular water-retaining agent is 20-120 meshes. Wherein the water reducing agent is used for reducing the water consumption for mixing, and 0.1-1 part of lignosulfonate is preferably used; the dispersant is used for reasonably dispersing the fried phosphogypsum powder in water, preferably 0.1-1 part of calcium lignosulphonate is adopted; the retarder is used for prolonging the hydration hardening time, so that the mixture keeps plasticity for a long time, and boric acid is preferably selected as the retarder and is used in 0.1-1 part; the reinforcing agent is used for enhancing the toughness of the building block, and preferably, the structural reinforcing fiber is a chemical fiber or a biological fiber and is used in 0.2-2 parts. It should be noted that the polymer water retention agent, the water reducing agent, the dispersant, the retarder and the reinforcing agent are not limited to the above-described products, and other products capable of playing the same role may be selected. In addition, the maximum amount of water used can be up to 33 parts.

2) Mixing materials: adding the raw materials according to the proportion, uniformly mixing and stirring for 70-100 seconds. In the step, firstly, a water reducing agent, a water retention agent and a dispersing agent are mixed with water in sequence to form mixed water; then adding the retarder and the reinforcing agent into the fried phosphogypsum powder to form a phosphogypsum powder mixture; and finally, pouring the mixed water into the phosphogypsum powder mixture for uniform stirring. The amount of the blend is 3 to 6 times the amount of the press molding material per time. In addition, when the equipment is equipped, the raw and auxiliary material bins are arranged near the raw and auxiliary material mixing and stirring device, and are arranged at an upper position or a side position, and the size of the raw and auxiliary material bins is matched with the number of the film cavities of the forming device and the unit dosage of the raw and auxiliary materials, so that the requirement of continuous production for the raw and auxiliary materials for 24 hours per day at least needs to be met. The preparation of self-control special adjuvant and water mixed liquid sets up accurate measurement and conveyor between self-control special adjuvant storehouse and upper water tank or side position water tank, before every batch of product production starts, according to the total amount calculation of water in the water tank, the water-retaining agent and the water-reducing agent of 1/290 of accurate total amount of adding water form the mixed water, and its mixed water is for use. Adding a retarder and a reinforcing agent into the fried phosphogypsum powder to form a phosphogypsum powder mixture for later use. The accurate metering and quick conveying device for the phosphogypsum powder mixture and the mixed water is arranged among the fried phosphogypsum storage bin, the water tank and the stirrer, and the fried phosphogypsum powder mixture and the mixed water are accurately and quickly added into the stirrer according to the calculation of the total material consumption and the proportion of the stirrer at one time. In the step, firstly adding the phosphogypsum powder mixture into a stirrer, then adding mixed water, finally carrying out high-speed rolling and fully stirring for 75 seconds to obtain a uniformly stirred mixture, and feeding the uniformly stirred mixture into a transition bin for later use.

3) And (3) pressing and forming: and pouring the mixture into a forming machine, pressing the mixture into a shape with the pressure of 180 tons and the pressure of 18-23 MPa for 20-30 seconds, and ejecting the phosphogypsum building blocks after the pressing is finished. And a transition bin is arranged between the mixing bin and the pressing forming machine, and the mixed materials are conveyed to the mixture transition bin and then conveyed to the distributing device through the transition bin for distribution. The uniform material distribution of the prefabricated molding die cavity is required to be rapid and completed within 8 seconds. After the uniform distribution is finished, the upper pressure head presses downwards with 180 tons of pressure, the movement stops after the traveling path reaches 50mm, then the lower pressure head presses upwards with 230 tons of pressure until the size ensures the set height, then the upper pressure head stops pressing for 3 seconds (static pressure for 3 seconds), the upper pressure head releases the pressure, and the lower pressure head continues to push the phosphogypsum building block upwards. It should be noted that the upper pressure head adopts a pressure of 100-180 tons, the lower pressure head adopts a pressure of 180-230 tons, and the pressed phosphogypsum block can also meet the quality requirement of the product, but when the upper pressure head adopts a pressure of 180 tons and the lower pressure head adopts a pressure of 230 tons, the quality of the pressed phosphogypsum block is optimal.

Keeping the same mixing proportion and time, adopting single-side advancing pressing with different pressing pressures (namely the upper pressing head adopts 180 tons of pressure, the lower pressing head adopts 150-250 tons of pressure), obtaining the following effects with the same material distribution amount and advancing distance and 25 seconds of pressing:

pressing pressure	Demolding strength of building block	Rate of hydration reaction	Quality of building block
				150 ton of	Difference (D)	Slow	Difference (D)
160 ton of	Difference (D)	Slow	Difference (D)
				170 ton of	Is poor	Is slower	Is poor
180 ton of	In	In	In
				190 tons	In	In	In
200 ton of	Is stronger	Is quicker	Is stronger
				210 ton of	Is stronger	Is quicker	Superior food
220 ton of	Is stronger	Fast-acting toy	Superior food
				230 ton of	High strength	Fastest speed	Superior food
240 tons	High strength	Is quicker	Is superior to
				250 tons	High strength	Slow	In

And (3) demolding strength of the building block: poor standards are not transportable or mobile (large collapses), medium standards are smooth and barely transportable by a belt (small collapses), strong standards are smooth and substantially transportable by a belt (substantially no collapses), and strong standards are substantially transportable by a belt (substantially no collapses). The demoulding strength of the building block is related to the intervention of the next procedure, and the demoulding strength is insufficient, so that collapse and scattering in the transportation process can be caused.

In the pressing process, the fact that the single-side advancing pressing is adopted can lead one side of the building block pressed firstly to be tighter and the other side of the building block to be looser, the pressing effect can be improved by adopting the up-down step-by-step pressing, the strength of the building block before pressing is very low, and 100% of pressure is not needed. And 100% pressure is adopted in the later stage of pressing, so that the overall strength of the building block can be kept consistent, and the pressing effect is improved.

In addition, the auxiliary agent containing the macromolecular water-retaining agent can absorb about 30 percent of water after being mixed with water, the volume of the auxiliary agent is expanded, and the auxiliary agent is uniformly mixed with the fried phosphogypsum powder and then is pressed and molded.

The rate of hydration reaction of the phosphogypsum block can be estimated by the amount of steam generated and the temperature, and the faster the reaction rate, the more steam generated and the more the temperature rises. The hydration reaction speed is high, the maintenance time of the phosphogypsum building blocks can be shortened, the production inventory and the occupied area are saved, and the production efficiency is improved. The faster the hydration reaction, the faster the temperature of the block rises, the more steam is generated. The hollow phosphogypsum building block has large void ratio, and the surrounding steam can increase the contact area of the phosphogypsum and water, thereby further promoting the rapid reaction.

The quality of the building block is measured after the building block is placed for 30 days after production, the difference is that the breaking load is less than DB 52/T1038-containing 2015 or the softening coefficient is less than 0.6, the breaking load is more than or equal to 2000N and less than or equal to 4000N, the softening coefficient is more than or equal to 0.6 and less than or equal to 0.8, the breaking load is more than 4000N and the softening coefficient is more than 0.8, which are excellent.

According to the experimental data and theoretical analysis, the scheme of the application is the optimal scheme.

4) Forming and maintaining: and (4) placing the pressed building blocks for 15-30 minutes and warehousing or leaving the factory. In order to finish the final setting of the gypsum blocks as soon as possible, the pressed blocks are placed in a plant, and steam collecting covers are arranged around and above the blocks and used for collecting steam generated by hydration reaction. And (3) conveying the demolded phosphogypsum block sample block by adopting a translation belt, conveying by using the translation belt for more than 15min, and accelerating high-heat steam curing and water evaporation formed by deepening hydration reaction by utilizing moderate water absorption and high-pressure extrusion to obtain the phosphogypsum block sample block which basically completes final setting. And (5) stacking the trays, and warehousing or leaving the factory. The phosphogypsum block sample block which finishes the walking of the translation conveying belt is stacked by standard trays, the hydration reaction completion rate of the phosphogypsum block sample block is more than 98 percent, the water content is about 12 percent generally, and the softening coefficient is more than 0.8 by gypsum analysis of the gypsum equivalence. According to the conditions of production field, storage, user requirements and the like, the materials can be continuously piled, aired and maintained, and put in storage or conveyed to users.

Therefore, the fried phosphogypsum powder starts to carry out hydration reaction after meeting water to generate calcium sulfate dihydrate, starts to increase strength after 1-3 minutes, has plasticity, is formed into a building block through high-pressure pressing, gradually releases water along with a hydration reaction macromolecule water-retaining agent until the hydration reaction is finished, finishes final setting of the phosphogypsum building block after about 15-30 minutes, and can be directly hoisted and transported to be put in storage or leave the factory. The hydration reaction of the fried phosphogypsum absorbs water and releases heat to expand, and at the moment, the macromolecular water-retaining agent releases water, so that the volume is reduced.

The free moisture of the phosphogypsum building block prepared by the method can be reduced by about 40 percent during demoulding, the demoulding strength is obviously improved, the product percent of pass is improved by more than 10 percent on the basis of the original process (CN 112745097A), the water consumption is obviously reduced compared with the water consumption of the traditional pouring method, the pressing time is obviously shortened, the product percent of pass is obviously improved, the process for mechanically and continuously producing the phosphogypsum building block is further perfected, and the production efficiency is greatly improved.

The phosphogypsum building block comprises, by weight, 100 parts of fried phosphogypsum powder, 25-30 parts of water and a proper amount of auxiliary agent. The auxiliary agents comprise a polymer water-retaining agent, a water reducing agent, a dispersing agent, a retarder and a reinforcing agent. Wherein the macromolecular water-retaining agent is 0.01-0.3 part, and comprises starch type, cellulose type and resin type, specifically polyacrylate, acrylic acid copolymer, polyvinyl alcohol, etc. The fineness of the macromolecular water-retaining agent is 20-120 meshes. Water reducing agent, dispersant, retarder and intensifier, the total dosage of which is 0.1-0.2%. Wherein, the water reducing agent is preferably lignosulfonate, and 0.1-1 part is adopted; the dispersant is preferably calcium lignosulfonate, and 0.1-1 part is adopted; boric acid is preferably selected as the retarder, and 0.1-1 part is adopted; the reinforcing agent is preferably a structural reinforcing fiber, and the structural reinforcing fiber is a chemical fiber or a biological fiber and is used in 0.2-2 parts.

In conclusion, the water-cement ratio of the phosphogypsum block produced by the method is reduced from 90% to 29%, the produced product does not need airing or drying procedures, 90 kilograms of standard coal are needed for drying one cubic meter of phosphogypsum block, and the time and capital cost for shortening the production period can reduce the production cost by more than 80 yuan per cubic meter of phosphogypsum block.

The method for producing the phosphogypsum building block can reduce the construction investment of a factory and save land resources. Taking the embodiment of the applicant as an example, the occupied area is 37400 square meters, the factory construction investment reaches more than 6000 ten thousand yuan, the natural airing period is long, the average time is about 30 days in spring and summer, the average time is about 60 days in autumn and winter, and 5 ten thousand cubic meters of phosphogypsum building blocks are produced at most every year. The method can produce 10 million cubic meters of phosphogypsum building blocks, the floor area only needs 2000 square meters, and the factory construction investment only needs about 1000 million. By adopting the invention, more than 5 block product production lines can be built in the space.

Realize the massive utilization of the phosphogypsum and other industrial by-product gypsum solid wastes. The phosphogypsum building block is used as a wall material for a non-bearing inner partition wall, is introduced into China from the 20 th century and the 80 th year, and is steadily developed in nearly 40 years, but is not widely applied like a cement wall material, wherein the main reason is that the traditional production method is low in input-output ratio, the number of factories is small, the number of large-scale factories is less, the capacity scale is small, and the requirement of engineering application cannot be met. According to statistics, the output of the phosphogypsum building blocks in China is only 2000 ten thousand square meters (calculated according to the thickness of 200 mm, 400 ten thousand cubic meters), and the amount of the gypsum powder prepared by stir-frying is about 250 ten thousand tons. According to statistics, the annual industrial byproduct gypsum emission amount in China is about 5000 ten thousand tons, the production is carried out according to the method, 10 ten thousand cubic meters of gypsum block production lines are produced annually, 7.3 ten thousand tons of fried gypsum powder can be utilized in each production line annually, and 10 ten thousand tons of byproduct gypsum can be consumed according to the condition that 1.4 tons of byproduct gypsum are fried to one ton of gypsum powder. If the method is popularized and applied in regions with large discharge amount of industrial by-product gypsum in China, a feasible path can be found for the resource utilization of the industrial by-product gypsum in bulk, and the method makes positive contribution to the utilization of the industrial by-product gypsum in solid waste and the innovation of wall materials in China.

The technology of the invention can reduce the amount of labor and the labor intensity of production workers. The annual output is calculated by a production line of 10 million cubic meters, only 4 persons are needed in each shift, 14 persons are needed by a vertical mold jacking machine according to the same productivity calculation, and 48 persons are needed by manual production by a flat mold. The labor intensity of the airing or drying process produced by the traditional method is very high, the airing or drying is not needed in the production by the method, the robot can be stacked and packaged when the production line comes out, and the forklift is forked into a storehouse, so that the labor intensity of production workers is low.

The initial setting time of the fried phosphogypsum powder, namely the building phosphogypsum powder, is required to be 3.5-5min (namely the initial setting is required to be a little earlier so as to be beneficial to forming certain strength in a die cavity through hydration reaction as soon as possible and quickly demould and leave the die cavity), the final setting time is more than 7min (namely the final setting is required to be slower so as to be beneficial to prolonging the time process of steam curing and water loss by utilizing hydration reaction to generate heat after demoulding), P2O5 is less than or equal to 1% (beneficial to reducing acidity so as to improve product quality), the standard consistency reaches about 70% (beneficial to forming higher compressive strength), the flexural strength reaches 2.8MPa or more in 2 hours, and the fried phosphogypsum powder is aged and homogenized as much as possible; the main component of the self-made special auxiliary agent is a material with high water absorption performance, which can quickly absorb and retain water and quickly release water under pressure (the patent application of the company: a semidry gypsum auxiliary agent and a preparation method thereof, application number: 2018108649085), can solve the problems of uniform water supply by stirring and emergency supply of water by quick hydration reaction in a die cavity; the chemical fiber or the biological fiber can be polypropylene fiber, hair, bristle, palm fiber and other fibers without emitting substances with certain strength and toughness, is similar to the action of a steel bar in concrete, is beneficial to rapid forming and forms certain strength and strengthens the breaking strength after maintenance; the proportion of water is 22.3 percent, which is equivalent to 28.79 percent of the weight of 77.45 percent of the fried phosphogypsum powder in the formula, and is an average value, and the proportion is controlled within about 22.3 percent and 0.2 percent due to different qualities of the fried phosphogypsum powder.

The raw material bin is arranged close to the front end of the stirring device, so that the conveying cost is reduced; the upper position or side position arrangement is beneficial to automatically adding raw and auxiliary materials and installing an intelligent metering device by utilizing natural gravity; the volume weight of the just demolded phosphogypsum building blocks is 20.5 kg per block under the natural state, a production line with 5 molding die cavity molding devices is provided, the daily production capacity in 24-hour continuous production can reach 330 and 350 cubic meters, at least 330 tons of the fried phosphogypsum powder are needed, and the minimum amount of the fried phosphogypsum raw material bins can reach 360 tons (180 tons/x 2 or 120 tons/x 3). Other auxiliary bins, including the water tank, should match according to the ratio, avoid lacking the material in the way of production to ensure the serialization production needs.

The metering requirement error of the fried phosphogypsum powder is less than 1 percent, and the metering error requirement of the mixed liquid of water and the self-made special auxiliary agent is less than 0.1 percent. The conveying time is required to be within 10-15 seconds, which is beneficial to ensuring continuous production and production efficiency by shortening the blanking time, and a pressurizing or pumping device is required to be arranged in the water tank for the purpose.

The high-speed grinding and full stirring are carried out, the revolution speed of the stirrer is required to be more than 180 revolutions per minute, a blade, a turning shovel and a wheel grinding device are arranged in the stirrer, and the rotating speed of the blade reaches more than 260 revolutions per minute so as to ensure that the inside of the stirrer is non-sticky and can work continuously. The mixture is required to be uniform, the surface has no clear water, and the mixture is moist and loose, can be kneaded into a ball by force and is scattered into a sand shape. The stirring time reaches 75 seconds, and the rapid stirring is beneficial to accelerating the water absorption of the fried phosphogypsum (semi-hydrated gypsum) to generate hydration reaction to reduce the fried phosphogypsum into the dihydrate gypsum. Because the stirring time of the mixture is 75 seconds, which is 2.27 times of the time of the next forming production process, the preparation amount of each batch of the mixture is required to reach 3-6 times of the required mixture amount for each batch of forming, and the stirrer is connected with the forming machine by using the transition bin, so that the continuous production of the forming machine can be ensured, and the mixture can not follow the forming requirement.

A certain number of 'mold cores' with certain size are required to be arranged according to the requirement of a product on reducing the volume weight so as to enable the gypsum block sample block to form hollow holes, the size of the block sample block is 600 × 200 mm, the central part of the block sample block is provided with 62.5 mm/6 hollow holes, the hollow holes are arranged in 2 rows, and each row of the 3 hollow holes can meet the requirement of the volume weight of 20.5 kg/block in demolding; the upper pressure head presses downwards by 180 tons per second, the pressure intensity unit is more than 18 MPa according to the conversion of the stress area of the upper pressure head, and the travel time is about 10 seconds; the lower pressure head 230 tons presses upwards and ejects out the block sample block, the pressure unit is converted into more than 20 MPa according to the stress area, and the time is about 12 seconds. The high-pressure static pressure for 3 seconds is beneficial to quickly releasing the moisture in the water-absorbing material in the self-made admixture, so that the hydration reaction of the mixture is accelerated to release the maximum heat, and the initial setting of the hydration reaction is accelerated to form a certain strength together with the fiber without sticking a mold. The total time of the material distribution and the forming process is 33 seconds, namely the material distribution time length is 8 seconds, the pressing stroke time length of the upper press head is 10 seconds, the pressing stroke time length of the lower press head is 12 seconds, and the static pressure is 3 seconds. In order to ensure that the high-pressure extrusion forming of the mixture stirred each time is completed before the initial setting so as to ensure the strength of the block sample, the mixture prepared in each batch needs to complete the forming process within 4min (from the time of adding the mixed liquid of 'water + self-made special auxiliary agent' to the time of completing the forming), so that the total amount of the mixture prepared in each batch is less than or equal to 6 times of the amount of the mixture required by the forming in each batch.

The initial strength of the ardealite block sample block just demoulded from the die cavity of the forming machine is mainly formed by high-pressure extrusion and pulling short fibers such as polypropylene and the like, so the ardealite block sample block needs to travel on a translation belt, and the translation belt needs to have small vibration amplitude and slow rotation speed during traveling. The hydration strength of the just demoulded block sample reaches the peak value, so that the surface temperature of the sample reaches over 45 ℃, and a large amount of water vapor is emitted. The sealing cover which is matched with the forming machine and is provided with a certain distance is required to seal the water vapor for curing the block sample. The length of the translation conveying belt can meet the translation conveying time of more than 15min according to the translation speed calculation, so that the hydration reaction of the gypsum blocks can be basically completed in the process of moving on the translation conveying belt, the final setting is achieved, and partial water is evaporated by fully utilizing the heat released by the hydration reaction.

The invention is illustrated by taking as an example a phosphogypsum block product which is produced for 24 hours continuously by adopting a production line with 5 phosphogypsum sample block molding die cavities and has the size of 600 × 200 mm:

1. preparing raw and auxiliary materials:

the invention is adopted, the process links for determining the production efficiency lie in a high-pressure extrusion forming process link and the number of formed die cavities, all other process links serve the process link, the preparation of the feeding and the mixture is to ensure that the forming die cavities work uninterruptedly to realize continuous production, and the translation belt is to ensure that the time of occupying the forming die cavities is shortened as much as possible by the block sample blocks, so that the final setting process is completed in the walking process. A production line with 5 phosphogypsum sample block molding die cavities is adopted to continuously produce phosphogypsum block products with the size of 600 × 200 mm for 24 hours, and the volume weight of the sample blocks is generally 20.5 kg per block when the sample blocks are demolded. Theoretically, the total amount of raw and auxiliary materials is 24 hours × 60 min/h × 60 s/min/33 s/1 batch, and the number of formed × 5 blocks/batch × 20.5 kg/block is 268.35 tons. Calculated according to the formula proportion of raw and auxiliary materials of 77.45% of fried phosphogypsum powder, 0.1% of self-made special auxiliary agent and 22.3% of water, 207.84 tons of fried phosphogypsum powder, 268.35 kilograms of self-made special auxiliary agent and 59.84 tons of water are needed. In the production practice, raw and auxiliary materials which are larger than the calculated raw and auxiliary materials are prepared respectively for standby.

2. Preparation of a mixed solution of an auxiliary agent and water:

the building gypsum powder is purchased at 360t (bulk vehicle is 40 t/vehicle), sampled by laboratory personnel to be used as raw materials, put in storage and detected (initial setting time is 4min, final setting time is 8min, water consumption of standard consistency is 69%, breaking strength is 2.8MPa after 2h, fineness is 100 meshes), and conveyed to A, B two bins by air flow for standby application (180 tons/vehicle is taken as an example for the two bins).

Preparation of auxiliary materials: dividing a 5-ton water tank into A, B bins, filling A, B bins with water (2.4 cubic meters per bin, the water outlet direction is connected by a gate valve and a tee joint and is controllable and communicated), weighing 16kg of auxiliary agent, respectively adding the auxiliary agent into A, B water tanks in equal amount, and stirring for 5min for later use. (after the storehouse A is used up, the storehouse B is opened for use).

0.5 kg/part of polypropylene fiber (high-strength yarn with the specification of 19mm to 25 mm) is weighed for standby (can be prepared in advance).

3. Arranging the personnel in place:

the equipment is positioned at 4 shifts/shift, (3 shifts for 12 people) in which: manually feeding fibers by a stirrer and patrolling 1 person; the host computer operates one man; a palletizing system is one person; one forklift worker can respectively locate each position according to the training requirement,

4. preparing equipment:

(1) according to the production process requirements, the following equipment is prepared: two 150t bins; two screw conveyors with the diameter of 320mm are arranged; 1000 planetary mixer with wheel roller, fly knife, turning shovel, and big arm with scraping wall; the mixture conveying belt is 600mm wide, 8000mm long and 160 r/min; 1.2m³A transition bin; a material distribution trolley; model 1300 static press (with mold); the hydraulic station can provide the power and the speed of the hydrostatic machine; an air compressor 11kw (cooling and drying machine); air cylinder (1.5 m)³) (ii) a A programmable PLC system; a power distribution cabinet; a translation flat belt steam curing system (a flat belt with the width of 1.5m and the length of 30m, a sealing cover and a negative pressure fan heating temperature and humidity sensor); a gantry type high-level stacker crane (which can grab a manipulator of 1.0m by 1.2m, has a height of 1m and stacks 5 layers of building blocks); a heavy chain plate discharging machine (with the length of 8m and the function of placing a supporting plate and with a stacking station and a packing station); 3t forklift one; 380V800A power supply; and assembling, connecting and debugging the equipment for standby.

5. Preparation before production:

(1) checking the oil levels of all lubricating oil and the positions of all sensors at all parts;

(2) and turning a control switch of the stirrer to a manual position, starting the stirrer, and operating the empty stirrer for one minute.

(3) And turning the control switch of the host to a manual position, starting the host and the air compressor, and enabling the components of the host and the like to act for a plurality of times after the pressure of the air compressor reaches 3.5 MPa.

(4) And the calibration metering system ensures that the raw and auxiliary materials are accurately metered and each feeding and discharging device is smooth.

(5) Programming (setting parameters):

raw material conveying time: 15 s;

measuring the blanking time of the metering barrel: 20 s;

pre-mixing time; 30s

Stirring time: 75s

Stirring weight: 500 kg;

additive solution added: 150 kg;

pressure of an upper pressure head: 180 t;

pressure of a lower pressure head: 230 t;

the product discharging speed is 25 s/time/5 blocks;

setting a batch: 700 batches are 3500 times;

compression ratio: 1.5: 1.0;

the product specification is as follows: 600*200*200

6. Turning the device control switch to the automatic direction:

(1) starting a feeding system and a metering system;

(2) starting a stirring system;

(3) starting a host;

(4) starting a translation maintenance system;

(5) starting a stacking system;

7. the gypsum block produced automatically is inspected by quality inspector and host operator for appearance size and performance, and the speed is calculated by stopwatch, and the product enters the translation maintenance system.

8. After 15min, the product is horizontally moved by a flat belt, cured by self-heat-generated steam, improved in strength, enters a stacking system, passes through ten blocks of each group, is intelligently and integrally stacked into 50 blocks, and is packed or enters a warehouse or is loaded to leave a factory.

The building blocks 414.72m are continuously produced by 24h of circulation and reciprocation according to the method³The compressive strength of the produced building block can reach more than 4.0MPa, the breaking load is more than 9000N, and the softening coefficient is more than 0.8. The net profit per cubic meter is 60 yuan, and the production profit can achieve 24883.2 yuan in 24 h.

Example 2

The embodiment 2 is different from the embodiment 1 in technical characteristics that:

1) preparing materials: preparing 100 parts of fried phosphogypsum powder, 25 parts of water, 0.01 part of a high-molecular water-retaining agent, 0.1 part of a water reducing agent, 0.1 part of a dispersing agent, 0.1 part of a retarder and 0.2 part of a reinforcing agent according to the weight part ratio; the fineness of the water retention agent is 20 meshes, and the water absorption rate is 100 times of the self weight.

2) Mixing materials: the raw materials are added according to the proportion, and are uniformly mixed and stirred for 70 seconds.

3) And (3) pressing and forming: and pouring the mixture into a forming machine, pressing for 20 seconds under the pressure of 180 tons and the pressure of 18 MPa, pressing and forming the mixture, and ejecting the building blocks after pressing.

4) Forming and maintaining: and (4) placing the pressed building block for 15 minutes and warehousing or leaving the factory.

The phosphogypsum building block comprises 100 parts of fried phosphogypsum powder, 25 parts of water and a proper amount of auxiliary agent according to the weight part ratio. The auxiliary agents comprise a polymer water-retaining agent, a water reducing agent, a dispersing agent, a retarder and a reinforcing agent. Wherein, the polymer water retention agent is 0.01 part, and the water reducing agent is 0.1 part; 0.1 part of dispersant; 0.1 part of retarder; 0.2 part of reinforcing agent; the fineness of the water retention agent is 20 meshes, and the water absorption rate is 100 times of the self weight.

Other technical features of this embodiment 2 are the same as those of embodiment 1.

Example 3

The embodiment 3 is different from the embodiment 1 in technical characteristics that:

1) preparing materials: preparing 100 parts of fried phosphogypsum powder, 28 parts of water, 0.1 part of a high-molecular water-retaining agent, 0.5 part of a water reducing agent, 0.5 part of a dispersing agent, 0.5 part of a retarder and 0.6 part of a reinforcing agent according to the weight part ratio; the fineness of the water retention agent is 80 meshes, and the water absorption rate is 500 times of the self weight.

2) Mixing materials: the raw materials are added according to the proportion, and are uniformly mixed and stirred for 85 seconds.

3) And (3) pressing and forming: and pouring the mixture into a forming machine, pressing for 25 seconds under the pressure of 210 tons and the pressure of 21 MPa, and performing compression forming on the mixture, and ejecting out the building blocks after the compression is finished.

4) Forming and maintaining: and (4) placing the pressed building block for 25 minutes and warehousing or leaving the factory.

The phosphogypsum building block comprises, by weight, 100 parts of fried phosphogypsum powder, 28 parts of water, 0.1 part of a high-molecular water-retaining agent and 0.5 part of a water-reducing agent; 0.5 part of dispersant; 0.5 part of retarder; 0.6 part of reinforcing agent; the fineness of the water retention agent is 80 meshes, and the water absorption rate is 500 times of the self weight.

Other technical features of this embodiment 3 are the same as those of embodiment 1.

Example 4

The embodiment 4 is different from the embodiment 1 in technical characteristics that:

1) preparing materials: preparing 100 parts of fried phosphogypsum powder, 30 parts of water, 0.3 part of a high-molecular water-retaining agent, 1 part of a water reducing agent, 1 part of a dispersing agent, 1 part of a retarder and 1 part of a reinforcing agent according to the weight part ratio; the fineness of the water retention agent is 120 meshes, and the water absorption rate is 1000 times of the self weight.

2) Mixing materials: the raw materials are added according to the proportion, and are uniformly mixed and stirred for 100 seconds.

3) And (3) pressing and forming: and pouring the mixture into a forming machine, pressing for 30 seconds under the pressure of 230 tons and the pressure of 23 MPa, and performing compression forming on the mixture, and ejecting out the building blocks after the compression is finished.

4) Forming and maintaining: and (4) placing the pressed building block for 30 minutes and warehousing or leaving the factory.

The phosphogypsum building block comprises, by weight, 100 parts of fried phosphogypsum powder, 30 parts of water, 0.3 part of a high-molecular water-retaining agent and 1 part of a water-reducing agent; 1 part of a dispersant; 1 part of retarder; the reinforcing agent is 1 part; the fineness of the water retention agent is 120 meshes, and the water absorption rate is 1000 times of the self weight.

Other technical features of this embodiment 4 are the same as those of embodiment 1.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

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. A semi-dry production method for preparing phosphogypsum building blocks in a mechanized and continuous manner comprises the following steps:

2) mixing materials: adding the raw materials in proportion, uniformly mixing and stirring for 70-100 seconds to form a mixture;

3) and (3) pressing and forming: pouring the mixture into a forming machine, firstly pressing downwards by an upper pressing head, then pressing upwards by a lower pressing head, keeping static pressing for 3 seconds after the pressure of 180 plus 230 tons and the pressure of 18-23 MPa reach the size of the building block in the pressing process of 20-30 seconds, pressing and forming the mixture, and ejecting the building block after the pressing is finished;

4) forming and maintaining: placing the pressed building blocks for 15-30 minutes and then warehousing or leaving the factory;

the auxiliary agent comprises 0.01-0.3 part of macromolecule water-retaining agent, 0.01-0.1 part of water reducing agent, 0.01-0.1 part of dispersing agent, 0.01-0.1 part of retarder and 0.02-0.2 part of reinforcing agent; the macromolecular water-retaining agent is resin;

in the material mixing step, firstly, a water reducing agent, a high-molecular water-retaining agent and a dispersing agent are sequentially mixed with water to form mixed water; secondly, adding a retarder and a reinforcing agent into the fried phosphogypsum powder to form a phosphogypsum powder mixture; then pouring the mixed water into the phosphogypsum powder mixture for fully stirring to form the mixture;

in the molding and maintaining step, the pressed building blocks are placed in a factory building, and steam collecting covers are arranged around and above the building blocks.

2. The semi-dry production method for the mechanical continuous preparation of the phosphogypsum building block according to claim 1 is characterized in that: the water absorption of the polymer water-retaining agent is 100-1000 times of the self weight, and the fineness of the polymer water-retaining agent is 20-120 meshes.

3. The semi-dry production method for the mechanical continuous preparation of the phosphogypsum building block according to claim 2 is characterized in that: the macromolecule water-retaining agent is selected from polyacrylate, acrylic acid copolymer and polyvinyl alcohol.

4. The semi-dry production method for the mechanical continuous preparation of the phosphogypsum building block according to claim 3, which is characterized in that: in the press forming step, the upper press head is pressed downwards with 180 tons of pressure, and the lower press head is pressed upwards with 230 tons of pressure.

5. The phosphogypsum block prepared by the semi-dry production method for mechanically and continuously preparing the phosphogypsum block according to any one of claims 1 to 4 is characterized in that: comprises 100 portions of fried phosphogypsum powder, 25 to 30 portions of water and a proper amount of auxiliary agent, wherein the auxiliary agent comprises 0.01 to 0.3 portion of macromolecule water-retaining agent, 0.01 to 0.1 portion of water reducing agent, 0.01 to 0.1 portion of dispersing agent, 0.01 to 0.1 portion of retarder and 0.02 to 0.2 portion of reinforcing agent; the macromolecule water-retaining agent is resin.

6. The phosphogypsum block of claim 5, which is characterized in that: the water absorption of the polymer water-retaining agent is 100-1000 times of the self weight, and the fineness of the polymer water-retaining agent is 20-120 meshes.

7. The phosphogypsum block of claim 6, which is characterized in that: the macromolecule water-retaining agent is selected from polyacrylate, acrylic acid copolymer and polyvinyl alcohol.