CN114684839A - Method for grading, mineralizing and carbon-fixing industrial by-product gypsum and gradient utilization of products - Google Patents

Abstract

The invention discloses a method for grading, mineralizing and fixing carbon by industrial by-product gypsum and utilizing products in a cascade manner₂Performing primary mineralization fixation on gas, filtering, drying and screening the mineralization product, stirring the oversize components, fly ash and steel slag according to a certain ratio, then pressing a film for 2-4 h in a film pressing machine, demoulding, then performing secondary mineralization in a mineralization reaction kettle, and controlling the temperature, humidity, pressure and CO of the mineralization reaction kettle₂The volume concentration is carried out, and the gel building material is obtained through carbonization and maintenance under a certain temperature condition; the undersize component is an ultrafine calcium carbonate component; and (4) feeding the filtrate after solid-liquid separation into a crystallizer for crystallization to obtain solid ammonium sulfate crystals. The invention not only improves the mineralization efficiency, but also realizes the mineralization product carbonic acidThe cascade utilization of calcium and the synergistic utilization of the fly ash reduce the energy consumption required by mineralization and carbon fixation, and have important significance for promoting the large-scale high-value utilization of the gypsum as a byproduct in the bulk industry of China.

Description

Industrial by-product gypsum graded mineralization carbon fixation and product cascade utilization method

technical field

The invention relates to the technical field of resource utilization of bulk solid waste, in particular to a method for grading mineralization and carbon-fixing of industrial by-product gypsum and a method for product cascade utilization.

Background technique

A large amount of industrial by-product gypsum is piled up, which not only occupies land, but also wastes resources. The harmful substances it contains can easily pollute the surrounding environment, which has become an important factor restricting the sustainable development of coal-fired units such as flue gas desulfurization and phosphate fertilizer.

Although there are many problems, the gypsum industry is still a model industry for recycling. At present, 70% to 80% of the raw materials are industrial by-product gypsum. If the industrial by-product gypsum is converted into high-purity gypsum, it is expected to replace natural gypsum as the raw material for industrial building materials. The related industries have a market space of hundreds of billions of yuan. Great growth potential. However, due to the complex composition of industrial by-product gypsum and the coexistence of many impurities, it is easy to cause environmental pollution, and the products have problems such as low whiteness, low strength, and easy cracking. In addition, extensive technology and insufficient product profit to offset transportation costs are important reasons for the difficulty in resource utilization of industrial by-product gypsum, low added value, and a large amount of accumulation. It is urgent to develop low-cost, large-scale clean and high-value utilization technologies.

At present, the use of industrial by-product gypsum to fix carbon is an effective way for its high-value utilization. The existing industrial gypsum carbon fixation technology is usually carried out in an ammonia medium, and the product calcium carbonate has a larger particle size and a lower economic value. In order to obtain high whiteness nanoscale calcium carbonate, it is necessary to add additives such as sodium sulfonate and sodium pyrophosphate to the carbon fixation system to reduce the particle size of the carbon fixation product calcium carbonate and improve its industrial value. However, this will inevitably affect the _CO2 absorption performance of the carbon fixation system, and have a negative impact on the quality of liquid-phase products (such as ammonium sulfate) and subsequent treatment (such as crystallization, wastewater discharge). The main products of industrial gypsum mineralization and carbon fixation are calcium carbonate and ammonium sulfate. Restricted by the limited economic value of the product, the cumbersome purification and impurity removal process, and high energy consumption, the mineralization and carbon fixation process aimed at producing filler calcium carbonate or slurry calcium carbonate has limited application prospects and is difficult to obtain economic benefits. The patent "Building Materials and Methods for Synergistic Carbonization of Steel Slag-Desulfurized Gypsum-Fly Ash" (Application No. 202011383245.9) discloses the use of steel slag, desulfurized gypsum, fly ash, sodium carbonate, ammonium bicarbonate, fine aggregate, coarse aggregate, A method for preparing building materials by co-carbonizing a retarder, a water reducing agent and a defoamer. Considering the wide supply range of building materials, it is possible to make its value-added utilization possible. However, this method adopts the process of first pressing and remineralization, reacting in two stages of high and low temperature, and has strict requirements on the carbon content and pressure in the mineralized flue gas. At the same time, there are high energy consumption and mineralization of calcium materials in solid waste Insufficient conversion rate, etc.

The invention adopts an alkaline solution such as ammonia as a medium, and adopts primary mineralization + re-compression molding + secondary coordinated fly ash mineralization to prepare building materials, which greatly improves the utilization efficiency of carbon in the mineralization process and reduces the severity of reaction conditions. . The graded utilization of calcium carbonate, the first-grade mineralized carbon-fixing product, improves the feasibility of product resource utilization, expands the research and development of industrial gypsum resource utilization technology, and has positive significance for environmental protection.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the invention provides a method for industrial by-product gypsum graded mineralization and carbon fixation and a product cascade utilization method, so that the industrial gypsum is preliminarily converted into calcium carbonate after the first-level mineralization and carbon fixation treatment, and according to the material The idea of making the best use of calcium carbonate with different particle sizes is used to obtain maximum economic benefits.

In order to realize the above-mentioned technical purpose, the present invention adopts the following technical solutions:

A method for industrial by-product gypsum graded mineralization and carbon _- fixing and product cascade utilization. First-grade mineralization, solid calcium carbonate is preliminarily prepared; after the solid calcium carbonate is screened by a vibrating screen, the components on the screen are mixed with fly ash and steel slag, and then pressed into a film, and then subjected to second-grade carbonization curing to obtain Cementitious building materials, the under-sieve component is ultra-fine calcium carbonate component.

Further, the method of the present invention specifically comprises the following steps:

S1. In the gas-liquid-solid three-phase enhanced reactor, add alkaline medium solution and industrial gypsum powder in turn, fully stir to form gypsum slurry, introduce carbon-containing flue gas for bubbling, increase the temperature, and after bubbling for a period of time, Discharge the slurry, then stand and filter to obtain calcium carbonate solid particles;

S2, the calcium carbonate solid particles obtained in S1 are dried and sieved to obtain a large on-screen component with a large particle and a small off-screen component; the off-screen component is an ultrafine calcium carbonate product, which is used for preparing light calcium carbonate;

S3, stirring the large particle calcium carbonate on the sieve obtained in S2 with fly ash, steel slag and water evenly;

S4, the mixture obtained in S3 is input into the compression molding machine for compression molding for a certain period of time to obtain the molding solid;

S5, the shaped solid obtained in S4 is input into the secondary mineralization reaction kettle, a certain concentration of flue gas is introduced, the temperature and humidity in the reaction kettle are adjusted, and the mineralization curing is carried out for a certain period of time to obtain a gelled mixture;

S6, pass the filtrate obtained in S3 into the crystallizer, evaporate and crystallize to obtain ammonium sulfate crystals, and circulate the mother liquor into the primary mineralization device.

Further, in S1, the industrial gypsum is one or more of phosphogypsum, sulfur gypsum and titanium gypsum.

Further, the industrial gypsum powder is firstly mineralized into calcium carbonate powder, and through sieving, the sieve components with large particles are mixed with a certain amount of fly ash and steel slag to form, and the secondary high-temperature mineralization is carried out to prepare cementitious building materials; The undersize fraction can continue to be used to make light calcium carbonate.

Further, in S1, the alkaline medium is ammonia water; the temperature is raised to 30-90° C., and the bubbling duration is 50-90 min.

Further, in S3, the ratio of the calcium carbonate to fly ash and steel slag is (20-60): (10-20): (30-60).

Further, in S4, the compression molding pressure is 20-30 Mpa, and the compression molding time is 2-4 hours.

Further, in S5, direct high temperature, normal pressure carbonization curing, adjusting the temperature in the reaction kettle to 90 ℃ ~ 250 ℃, the relative humidity is controlled at 70% ~ 90%, and the mineralization curing time is 3h ~ 6h.

Further, in S5, the volume concentration of CO ₂ in the introduced flue gas is above 1%.

Further, the flue gas is industrial waste gas containing CO ₂ .

Further, the device used in the present invention includes: a gas-liquid-solid three-phase enhanced reactor, a vibration screening device, a filter separation device, a compression molding machine, a mineralization reactor, a flue gas conveying device, a sulfate crystallizer and a mother liquor reflux. Tube.

Beneficial effects:

The method of the invention can realize the fully classified utilization of industrial gypsum, greatly improve the carbon conversion and utilization rate, reduce the harsh requirements of the mineralization reaction conditions and the energy consumption, and prepare the obtained products by grading mineralization and separately utilizing the carbon-fixing products of different particle sizes. Medium and coarse calcium carbonate can synergize with fly ash to prepare building materials, and fine calcium carbonate can be used as an industrial filler. The method of the invention can improve the resource utilization efficiency, and has great significance for the high-value resource utilization of industrial by-product gypsum.

Description of drawings

Fig. 1 is the process flow diagram of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Example 1

The present embodiment provides a method for industrial by-product gypsum graded mineralization carbon fixation and product cascade utilization, comprising the following steps:

Turn on the reaction device, put the weighed 10kg of desulfurized gypsum into the gas-liquid-solid three-phase enhanced reactor, add 50L of water to dissolve, add 1:20 ammonia water, turn on the stirring device, set the rotating speed to 200-400rpm, and stir at a constant speed. When the temperature rises to 80 °C, the flue gas containing CO ₂ is introduced, and the flow rate is set. The stirring device is turned on, and the solid-liquid separation is carried out after the carbon-fixing conversion of the desulfurized gypsum for 1 hour, and the solid product is taken out. The solid obtained by dehydration and pressure filtration is dried by the residual heat of flue gas for 2 hours to obtain the first-grade mineralized calcium carbonate solid.

The first-grade mineralized product solid obtained above was placed on a vibrating screen for screening, and the components on the screen were mixed with fly ash and steel slag in a ratio of 20:20:60 and then entered into the compression molding machine. After 4 hours of compression molding at 20MPa Input the mineralization reaction kettle, control the temperature of the reaction kettle to be 40°C, the humidity to be 70%, and pass the flue gas (CO ₂ content 15%), after the reaction for 2h, raise the temperature to 250°C, keep the humidity at 70%, and continue to feed After the flue gas reacted for 4 hours, a gelling material was obtained.

The fraction under the sieve is a calcium carbonate product with finer particles, which can be directly used industrially.

The filtrate after solid-liquid separation enters the crystallizer, and the ammonium sulfate salt solution is concentrated, evaporated and crystallized by using the waste heat of flue gas, and the by-product of ammonium sulfate salt particles with a content of 94.0% is obtained after solid-liquid separation and drying. The filtered crude mother liquor can also be recycled for the preparation of mineralized products.

Example 2

The present embodiment provides a method for industrial by-product gypsum graded mineralization carbon fixation and product cascade utilization, comprising the following steps:

After removing iron from titanium gypsum by reduction bleaching method, turn on the reaction device. When the temperature rises to 90 °C, put 10 kg of iron-removed titanium gypsum weighed into the reactor, add 50 L of deionized water to dissolve, Add 1:20 ammonia water. Turn on the stirring device and turn off the stirring device after thorough mixing. At this time, the pressure reducing valve was opened, the flue gas (CO ₂ content 15%) was introduced, the mass flow meter was opened, and the flow rate was set. The stirring device is also turned on, the rotation speed is set at 200-400 rpm, and the stirring is uniform. After the titanium gypsum carbon fixation conversion reaction is completed, the slurry is taken out, placed in a precipitation separation device for solid-liquid separation, and the solid product flue gas waste heat is dried for 2 hours to obtain ultra-fine calcium carbonate particles.

The ultrafine calcium carbonate particles obtained above are input into the vibrating screen for screening, and the components on the screen are mixed with fly ash and steel slag according to the ratio of 44:20:36 and then enter the compression molding machine. Mineralization reaction kettle, the temperature of the reaction kettle is controlled to be 50 ° C, the humidity is 80%, and the flue gas (CO ₂ content of 15%) is introduced. After 2 hours of reaction, the temperature is raised to 250 ° C, and the humidity is kept at 80%, and the smoke is continued to be introduced. The gelling material was obtained after 4 h of gas reaction.

The fraction under the sieve is a calcium carbonate product with finer particles, which can be directly used industrially.

The filtrate after solid-liquid separation enters the crystallizer, and the ammonium sulfate salt solution is concentrated, evaporated and crystallized by the waste heat of flue gas, and the by-product of ammonium sulfate salt particles with a content of 94.3% is obtained after solid-liquid separation and drying. The filtered crude mother liquor can also be recycled for the preparation of mineralized products.

Example 3

The present embodiment provides a method for industrial by-product gypsum graded mineralization carbon fixation and product cascade utilization, comprising the following steps:

After removing iron from titanium gypsum by reduction bleaching method, turn on the reaction device. When the temperature rises to 90 °C, put 10 kg of iron-removed titanium gypsum weighed into the reactor, add 50 L of deionized water to dissolve, Add 1:20 ammonia water. Turn on the stirring device and turn off the stirring device after thorough mixing. At this time, the pressure reducing valve was opened, the flue gas (CO ₂ content 15%) was introduced, the mass flow meter was opened, and the flow rate was set. The stirring device is also turned on, the rotation speed is set at 200-400 rpm, and the stirring is uniform. After the titanium gypsum carbon fixation conversion reaction is completed, the slurry is taken out, placed in a precipitation separation device for solid-liquid separation, and the solid product flue gas waste heat is dried for 2 hours to obtain ultra-fine calcium carbonate particles.

The ultra-fine calcium carbonate particles obtained above are input into the vibrating screen for screening, and the components on the screen are mixed with fly ash and steel slag according to the ratio of 50:20:30 and then enter the compression molding machine. Mineralization reaction kettle, the temperature of the reaction kettle is controlled to be 50 ° C, the humidity is 80%, and the flue gas (CO ₂ content of 15%) is introduced. After 2 hours of reaction, the temperature is raised to 250 ° C, and the humidity is kept at 80%, and the smoke is continued to be introduced. The gelling material was obtained after 4 h of gas reaction.

The fraction under the sieve is a calcium carbonate product with finer particles, which can be directly used industrially.

The filtrate after solid-liquid separation enters the crystallizer, and the ammonium sulfate salt solution is concentrated, evaporated and crystallized by the waste heat of the flue gas, and the by-product of ammonium sulfate salt particles with a content of 94.2% is obtained after solid-liquid separation and drying. The filtered crude mother liquor can also be recycled for the preparation of mineralized products.

Example 4

The present embodiment provides a method for industrial by-product gypsum graded mineralization carbon fixation and product cascade utilization, comprising the following steps:

Turn on the reaction device, when the temperature rises to 90 ℃, put the weighed 10 kg of desulfurized gypsum into the reactor, add 50 L of deionized water to dissolve, and add 1:20 ammonia water. Turn on the stirring device and turn off the stirring device after thorough mixing. At this time, the pressure reducing valve was opened, the flue gas (CO ₂ content 15%) was introduced, the mass flow meter was opened, and the flow rate was set. The stirring device is also turned on, the rotation speed is set at 200-400 rpm, and the stirring is uniform. After the titanium gypsum carbon fixation conversion reaction is completed, the slurry is taken out, placed in a precipitation separation device for solid-liquid separation, and the solid product flue gas waste heat is dried for 2 hours to obtain ultra-fine calcium carbonate particles.

The ultra-fine calcium carbonate particles obtained above are input into the vibrating screen for screening, and the components on the screen are mixed with fly ash and steel slag according to the ratio of 50:20:30 and then enter the compression molding machine. Mineralization reaction kettle, the temperature of the reaction kettle is controlled to be 50°C, the humidity is 80%, and the flue gas (CO ₂ content is 15%) is introduced. After 2 hours of reaction, the temperature is raised to 150°C, the humidity is kept at 80%, and the smoke is continued to be introduced. The gelling material was obtained after 4 h of gas reaction.

The fraction under the sieve is a calcium carbonate product with finer particles, which can be directly used industrially.

The filtrate after solid-liquid separation enters the crystallizer, and the ammonium sulfate salt solution is concentrated, evaporated and crystallized by the waste heat of the flue gas, and the by-product of ammonium sulfate salt particles with a content of 94.5% is obtained after solid-liquid separation and drying. The filtered crude mother liquor can also be recycled for the preparation of mineralized products.

Table 1-Examples 1-4 Compression Mold and Carbonization Process

Table 2 - Compressive strength of carbonization process and corresponding building materials in Examples 1 to 4

As shown in Tables 1-2, the compressive strength of the building materials prepared by the synergistic carbonization of industrial by-product gypsum-fly ash prepared in Examples 1-4 was tested. It can be seen from Examples 1, 2 and 3 that increasing the calcium content can improve the strength of the material. It can be seen from Examples 3 and 4 that the strength of the material obtained by reducing the curing temperature of the second stage of the secondary mineralization reactor will decrease.

The invention uses the industrial by-product gypsum as the mineralization and carbon fixation carrier to mineralize and fix the _CO2 in the flue gas in two stages, which not only improves the carbonization conversion rate, but also realizes the cascade utilization of the mineralized product calcium carbonate and fly ash. The synergistic utilization reduces the energy consumption required for mineralization and carbon fixation, and provides an effective method for the synergistic resource utilization of desulfurized gypsum and fly ash. The invention has the advantages of low energy consumption, high mineralization efficiency, green and simple process, good product performance, low cost and the like, and is of great significance for promoting the large-scale and high-value utilization of by-product gypsum in my country's bulk industry.

The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions that belong to the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims (10)

1. The method for grading, mineralizing and carbon fixation of industrial by-product gypsum and gradient utilization of products is characterized in that the industrial by-product gypsum is used as a calcium source in an alkaline medium solution, and CO in flue gas is treated in a gas-liquid-solid three-phase enhanced reactor₂Carrying out primary mineralization to prepare solid calcium carbonate; after solid calcium carbonate is screened by a vibrating screen, the components on the screen, the fly ash and the steel slag are proportioned and stirred, then film pressing is carried out, secondary carbonization maintenance is carried out to obtain a gelled building material, and the components under the screen are superfine calcium carbonate components.

2. The method for graded mineralization and carbon fixation of industrial by-product gypsum and cascade utilization of products according to claim 1, comprising the following steps:

s1, sequentially adding an alkaline medium solution and industrial gypsum powder into a gas-liquid-solid three-phase enhanced reactor, fully stirring to form gypsum slurry, introducing carbon-containing flue gas for bubbling, raising the temperature, discharging the slurry after the bubbling lasts for a period of time, and then standing and filter-pressing to obtain calcium carbonate solid particles;

s2, drying and screening the calcium carbonate solid particles obtained in the step S1 to obtain oversize components with large particles and undersize components with small particles; the undersize component is an ultrafine calcium carbonate product and is used for preparing light calcium carbonate;

s3, uniformly stirring the large-particle calcium carbonate of the oversize component obtained in the step S2 with the fly ash, the steel slag and the water, and then carrying out solid-liquid separation;

s4, inputting the solid mixture obtained in the S3 into a molding press for compression molding for a certain time to obtain a molded solid;

s5, inputting the molded solid obtained in the step S4 into a secondary mineralization reaction kettle, introducing smoke with a certain concentration, adjusting the temperature and humidity in the reaction kettle, and carrying out mineralization maintenance for a certain time to obtain a gelled mixture;

and S6, introducing the filtrate obtained in the step S3 into a crystallizer, evaporating and crystallizing to obtain ammonium sulfate crystals, and circularly feeding the mother liquor into a primary mineralization device.

3. The method for graded mineralization and carbon sequestration of industrial by-product gypsum and product cascade utilization according to claim 1, wherein in S1, the industrial gypsum is one or more of phosphogypsum, thiogypsum and titanium gypsum.

4. The method for graded mineralization and carbon fixation of industrial by-product gypsum and product gradient utilization according to claim 1, wherein in S1, the alkaline medium is ammonia water; raising the temperature to 30-90 ℃, wherein the bubbling duration is 50-90 min.

5. The method for graded mineralization and carbon fixation of industrial by-product gypsum and cascade utilization of products according to claim 1, wherein in S3, the ratio of calcium carbonate to fly ash to steel slag is (20-60): (10-20):

(30～60)。

6. the method for staged mineralization and carbon fixation of industrial by-product gypsum and cascade utilization of products as claimed in claim 1, wherein in S4, the pressure of the compression molding is 20-30 Mpa, and the compression molding time is 2-4 h.

7. The method for graded mineralization and carbon fixation of industrial by-product gypsum and cascade utilization of products according to claim 1, wherein in S5, the temperature in the reaction kettle is adjusted to 90-250 ℃, the relative humidity is controlled to 70-90%, and the mineralization maintenance time is 3-6 h.

8. The method for graded mineralization and carbon fixation of industrial by-product gypsum and product gradient utilization according to claim 1, wherein in S5, CO is introduced into flue gas₂The volume concentration of (A) is more than 1%.

9. The method for graded mineralization and carbon fixation of industrial by-product gypsum and product gradient utilization according to claim 1, wherein the flue gas is CO-containing flue gas₂Industrial waste gas of (2).

10. The method for graded mineralization and carbon fixation of industrial by-product gypsum and cascade utilization of products according to claim 1, wherein the applied devices comprise: the device comprises a gas-liquid-solid three-phase reinforcing reactor, a vibration screening device, a filtering and separating device, a molding press, a mineralization reaction kettle, a flue gas conveying device, a sulfate crystallizer and a mother liquor return pipe.

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