CN115400577A - Steel slag mixed with clay and limestone pulping desulfurization method and mixed desulfurizer - Google Patents

Abstract

The application discloses a desulfurization method for mixed pulping of steel slag, clay and limestone and a mixed desulfurizer. The mixed desulfurizer comprises waste steel slag particles, clay particles and limestone particles which are uniformly mixed. According to the application, the waste steel slag mixed clay, limestone and the like are adopted to prepare the mixed desulfurizer, so that the raw material source is wide, the cost is low, the waste steel slag can be effectively utilized, the components such as sulfur dioxide in sulfur-containing flue gas can be removed by the mixed desulfurizer at high efficiency and low cost, and the purpose of treating waste with waste is achieved; meanwhile, the by-product of the mixed desulfurizer after desulfurization of sulfur-containing flue gas has the advantages of small particles, convenience in processing and the like, can be used as a raw material in cement plants and building industries, does not generate secondary pollution, and the prepared building material also has the advantages of high strength, low cost and the like, so that comprehensive utilization of resources is realized.

Description

Steel slag mixed with clay and limestone pulping desulfurization method and mixed desulfurizer

technical field

The application relates to a flue gas desulfurization method, in particular to a desulfurization method for mixing steel slag with clay and limestone and a mixed desulfurizer, which belongs to the technical field of environmental protection.

Background technique

In 2020, my country's crude steel output will exceed 1 billion tons, and the corresponding steel slag will account for 10% to 15% of the crude steel output, that is, the steel slag output will exceed 100 million tons. However, the comprehensive utilization rate of steel slag is not high at present, only about 30%. Therefore, a large amount of steel slag is produced every year and cannot be used, and it takes up a large amount of land area to be piled up year by year, and what is more serious is to cause environmental pollution. At present, the effective way to utilize large amounts of steel slag and high added value is to produce steel slag powder, which can be used in building materials, construction, concrete, roads, etc. The produced steel slag powder has outstanding problems such as low early strength, which seriously restricts its large-scale production and engineering application.

On the other hand, in recent years, the annual emission of sulfur dioxide in my country has been around 20 million tons. Since the losses caused by nitrogen oxides and sulfur oxides to my country are more than 10 billion yuan per year, these pollutants mainly come from the flue gas emitted by coal-fired boilers, smelting, sintering and other industries. In order to reduce environmental pollution, it is generally necessary to remove sulfur dioxide and other pollutants in these flue gases before they can be discharged into the atmosphere. At present, the desulfurization facilities built and put into operation by large electric power and metallurgical enterprises basically adopt Ca-based wet, dry, and semi-dry desulfurization technologies, and the main chemical components of desulfurization by-products are CaSO ₄ , CaSO ₃ , CaCO ₃ and CaO. For these by-products, there is no good disposal method at present, but stacking and landfilling are the main methods, which not only occupy industrial land, but also cause secondary pollution to water sources, soil and air if not handled properly.

How to realize more efficient utilization of waste steel slag and effective disposal of flue gas desulfurization by-products has become an urgent problem to be solved in the industry.

Contents of the invention

The main purpose of this application is to provide a desulfurization method for mixing steel slag with clay and limestone and a mixed desulfurizer to overcome the deficiencies in the prior art.

In order to realize the aforementioned object of the invention, the technical solutions adopted in this application include:

One aspect of the present application provides a mixed desulfurizer, which includes 45wt%-55wt% waste steel slag, 25wt%-35wt% clay and 15wt%-25wt% limestone.

In one embodiment, the waste steel slag, clay, and limestone are all in granular form, and the particle size is below 100 mesh, such as 100 mesh to 200 mesh.

In one embodiment, the clay comprises attapulgite clay.

Another aspect of the present application provides a desulfurization slurry, which includes the mixed desulfurizer and water, and the solid content of the desulfurization slurry is 10wt%-15wt%, and the pH value is above 8.5.

In this application, the waste steel slag is the waste slag discharged during the steelmaking process, the chemical composition is mainly oxides of silicon, calcium, magnesium, iron, etc., and the main phase composition is tricalcium silicate, dicalcium silicate, iron calcium oxide, iron oxide, etc.

In this application, the clays are generally formed from aluminosilicate minerals after the weathering of the earth's surface, but some diagenesis also produces clays. Preferably, the clay is attapulgite clay, which is called attapulgite for short, and has a block-like structure, and the color is off-white, blue-gray, light yellow and light green. Greasy luster, light specific gravity, Mohs hardness 2-3, viscous and plastic when wet, small drying shrinkage, no cracks, strong water absorption, which can reach more than 150%, and pH value of about 8.5.

In this application, the limestone is a natural material whose main component is CaCO ₃ , which can react with sulfur dioxide gas under certain conditions, so as to achieve the purpose of desulfurization.

In the mixed desulfurizer of the present application, steel slag, clay, limestone and other main components have huge reserves, and all of them can react with sulfur dioxide in flue gas, thereby realizing desulfurization. In particular, this application prepares desulfurization slurry by mixing steel slag, clay and limestone in a certain proportion, which contains a large amount of alkaline substances, which can react with SO ₂ . This application adopts a uniform mixture of steel slag, clay and limestone as a desulfurizing agent, which can not only reduce the cost of desulfurization, but also enable comprehensive utilization of steel slag, so as to achieve the purpose of "treating waste with waste".

Another aspect of the present application provides a desulfurization method for mixing steel slag with clay and limestone, which includes:

(1) After the waste steel slag, clay and limestone are removed and pulverized, they are evenly mixed to obtain the mixed desulfurizer;

(2) uniformly mixing the mixed desulfurizing agent prepared in step (1) with water to make the desulfurization slurry;

(3) Fully contacting the sulfur-containing flue gas with the desulfurization slurry prepared in step (2) to realize the desulfurization treatment of the sulfur-containing flue gas.

In one embodiment, the desulfurization method specifically includes:

(1) Carry out impurity removal treatment on waste steel slag, clay, and limestone, and then perform drying and crushing treatment in sequence, and then uniformly mix the obtained waste steel slag particles, clay particles, and limestone particles to prepare a mixed desulfurizer;

(2) uniformly mixing the mixed desulfurizer and water in the reaction tower to make the desulfurization slurry;

(3) The sulfur-containing flue gas is input into the reaction tower from the lower part of the reaction tower, so that the sulfur-containing flue gas and the desulfurization slurry are fully contacted and reacted in the reaction tower, so that at least part of the sulfur-containing flue gas contains The sulfur component is removed, and then the flue gas after desulfurization treatment is discharged from the flue gas discharge port of the reaction tower;

Wherein, the sulfur-containing component includes sulfur dioxide.

In one embodiment, there are a plurality of reaction towers, and the step (3) further includes: allowing the sulfur-containing flue gas to pass through the plurality of reaction towers sequentially, and fully mix with the desulfurization slurry in each reaction tower Contact and react until the composition of the flue gas reaches the emission standard, then discharge the flue gas into the atmosphere from the flue gas outlet of the last reaction tower.

In one embodiment, step (3) further includes: when the pH value of the desulfurization slurry in the reaction tower is reduced to 4-5, then discharging the desulfurization slurry as a waste liquid to a waste liquid pool, and re-discharging the desulfurization slurry in the reaction tower. The desulfurization slurry with a pH value above 8.5 is put into the reaction tower.

In one embodiment, step (3) further includes: setting a stirrer in the reaction tower to fully stir the desulfurization slurry in the reaction tower.

In one embodiment, the desulfurization method further includes: separating the solid phase in the waste liquid, followed by drying, and then applying to prepare building materials.

Another aspect of the present application provides a desulfurization system, comprising:

Mixed desulfurizer production unit, including:

The first dryer is used to dry waste steel slag, clay and limestone,

Particle pulverizer, used for pulverizing waste steel slag, clay and limestone after drying treatment,

Feeder, used to input the mixed desulfurizer into the reaction tower, the mixed desulfurizer is mainly formed by uniform mixing of crushed waste steel slag, clay and limestone;

At least one reaction tower, the upper part of the reaction tower is provided with a feeding port and a water inlet, the upper or middle part is provided with a flue gas discharge port, and the lower part is provided with a flue gas inlet and a liquid discharge port, wherein the feeding port, water inlet, flue gas The inlets are respectively connected with the feeding machine, the water delivery pipeline, and the source of sulfur-containing flue gas, and are respectively used to input mixed desulfurizer, water, and sulfur-containing flue gas into the inner cavity of the reaction tower. The desulfurized flue gas is discharged from the reaction tower, and the liquid outlet is used to discharge the waste liquid from the reaction tower. The waste liquid is generated after the desulfurization slurry and the sulfur-containing flue gas fully contact and react, and the waste liquid The pH value is 4-5, and the desulfurization slurry is mainly formed by mixing a mixed desulfurization agent and water.

In one embodiment, the feeder may be a crawler feeder or other feeding device, and is not limited thereto.

In one embodiment, the sources of sulfur-containing flue gas include sintering furnaces, thermal power plants, industrial boilers, coal chemical plants, steel mills, etc., but are not limited thereto.

In one embodiment, the desulfurization system includes multiple reaction towers arranged in series. Specifically, the flue gas outlet of the upper reaction tower is connected with the flue gas inlet of the lower reaction tower. In this case, the upper reaction tower is equivalent to the sulfur-containing flue gas generation source of the lower reaction tower.

In one embodiment, a stirrer is also provided in the reaction tower, and the stirrer is used to fully stir the desulfurization slurry in the reaction tower.

In one embodiment, the desulfurization system may further include a waste liquid pool for containing the waste liquid discharged from the reaction tower.

In one embodiment, the desulfurization system may also include other supporting equipment, such as a device for separating solids from the waste liquid in the waste liquid pool, a device for drying and subsequent processing of the solids Wait.

In addition, the desulfurization system may also include various temperature detection equipment, humidity detection equipment, pressure detection equipment, pH value detection equipment, flue gas composition analysis equipment, etc. All kinds of valves, flow meters and other equipments that are matched with the pipelines can be installed in the desulfurization system according to the known equipments in the art, so the details will not be repeated here.

Compared with the prior art, the advantages of the technical solution of the present application are at least:

(1) By using waste steel slag mixed with clay, limestone, etc. to make a mixed desulfurizer, not only the source of raw materials is extensive and the cost is low, but also the effective utilization of waste steel slag can be realized, and the mixed desulfurizer can desulfurize with high efficiency and low cost. By removing sulfur dioxide and other sulfur-containing components in sulfur-containing flue gas, the purpose of "treating waste with waste" is achieved.

(2) Using the mixed desulfurizer to desulfurize the by-products of sulfur-containing flue gas has the advantages of small particles and easy processing, and can be used as raw materials in cement plants and construction industries, such as for the production of cement, bricks and tiles, etc. , will not produce secondary pollution, and realize the comprehensive utilization of resources.

Description of drawings

Fig. 1 is a schematic structural view of a desulfurization system in an embodiment of the present application;

Explanation of reference signs: 1-source of sulfur-containing flue gas; 2-control valve; 3-reaction tower; 4-waste liquid pool; 5-flow pump; 6-stirrer; 7-flue gas analyzer; 8-track Feeding machine; 9-particle pulverizer; 10-clean flue gas discharge port; 11-first dryer; 12-second dryer; 13-cement factory; 14-brick and tile factory.

Detailed ways

The technical solutions of the present application will be explained in more detail below in conjunction with several embodiments, but these specific descriptions are only used to teach those skilled in the art how to implement the present application, rather than exhaustively enumerating all possible ways of the present application , and are not intended to limit the scope of this application.

Example 1

This embodiment provides a desulfurization method for mixing steel slag with clay and limestone. The process is mainly as follows: first, remove impurities and pulverize waste converter steel slag, attapulgite clay and limestone, and then mix them uniformly in proportion. Prepare a mixed desulfurizing agent, then uniformly mix the mixed desulfurizing agent with water to form a desulfurization slurry; then fully contact the sulfur-containing flue gas with the desulfurization slurry, thereby realizing the desulfurization treatment of the sulfur-containing flue gas.

In this embodiment, the desulfurization method is mainly implemented based on the desulfurization system shown in FIG. The first dryer 11 and so on. There can be more than two reaction towers 3, which are arranged in series in multiple stages.

Further, the desulfurization method specifically includes the following steps:

S1. Perform impurity removal treatment on waste steel slag, clay, and limestone in a conventional manner, and then dry waste steel slag, attapulgite clay, and limestone with the first dryer 11 to remove steel slag, clay, and limestone. It prevents it from becoming a slurry when it enters the pulverizer, so as to ensure better pulverization.

S2. The waste steel slag, clay, and limestone treated in step S1 are respectively pulverized with a particle crusher 9 until the particle diameter is less than 100 mesh, which can significantly increase the specific surface area of these mixed desulfurizer components, and not only make it easier to fully mix , and can improve the desulfurization efficiency in the desulfurization process. Afterwards, the granular waste steel slag, clay and limestone are uniformly mixed according to the mass ratio of about 5:3:2 to make a mixed desulfurizer.

S3. Input the mixed desulfurizer prepared in step S2 from the feeding port at the top of each reaction tower 3 into the reaction tower 3 through the crawler feeder 8, and at the same time feed water from the water inlet at the top of each reaction tower 3 with a water delivery pipeline Enter reaction column 3. The water delivery pipeline is provided with a flow pump 5, which is used for proportioning according to the amount of the mixed desulfurizing agent entering the reaction tower, so as to supply a suitable volume of water, so that the mixed desulfurizing agent entering the reaction tower is mixed with water. A desulfurization slurry with a solid content of about 10wt% and a pH value above 8.5 is formed. In order to prevent the waste steel slag, clay and limestone from settling in the desulfurization slurry, and to ensure that the three are fully reacted and mixed evenly, it is preferable to install a stirrer 6 in the reaction tower for sufficient stirring.

S4. Provide sulfur-containing flue gas with sulfur-containing flue gas generation source 1. After passing through the flue gas delivery pipeline with control valve 2, the sulfur-containing flue gas enters the reaction tower from the flue gas inlet provided at the lower part of the side of the reaction tower 3, and Fully react with the desulfurization slurry in it, so that the sulfur dioxide and other components in the sulfur-containing flue gas are at least partially removed. discharge. In order to prevent a desulfurization process from failing to achieve the desired desulfurization effect, it is preferable to set up a second reaction tower or more reaction towers to desulfurize again, as shown in Figure 1, that is, to make the desulfurized smoke discharged from the first reaction tower The flue gas enters the flue gas inlet of the second reaction tower, and fully contacts with the desulfurization slurry again, and so on, until the flue gas is discharged from the flue gas outlet of the last reaction tower. The flue gas outlet of the last reaction tower can be defined as a net flue gas outlet 10, and a smoke analyzer 7 can be arranged at the net flue gas outlet 10 to detect the flue gas after the last reaction tower desulfurization treatment. Chemical composition to determine whether it meets the emission requirements, and the desulfurized flue gas that meets the emission standards is discharged into the atmosphere through the net flue gas discharge port 10.

In this step, when the desulfurization slurry in any reaction tower has sufficient components such as sulfur dioxide in the flue gas, and the pH value reaches 4-5, its desulfurization effect will decrease, and it cannot be continuously absorbed and used, and it will become waste liquid. The waste liquid can be discharged into the waste liquid pool 4 through the liquid discharge port arranged at the lower part of the reaction tower 3 and the control valve matched therewith.

Further, the desulfurization system may also include facilities such as a second dryer 12, a cement factory 13, and a brick and tile factory 14. And the desulfurization method may also include:

Fully settle the waste liquid entering the waste liquid pool 4, so that the solids therein (mainly the reaction products of waste steel slag, clay, lime and sulfur dioxide in the flue gas, i.e. desulfurization products) settle to the bottom of the waste liquid pool, Drain the clear water from the upper layer, and send the sediment from the lower layer to the second dryer 12 for processing. The processed product is a good raw material for the construction industry. It has the advantages of small particles and easy processing, and can be sent to Cement factory 13, brick and tile factory 14, etc. are used as production raw materials, and can be further processed into cement products, brick and tile, etc.

The barium sulfate gravimetric method (GB/T176-1996) was used to measure the sulfur content in the desulfurized product. It can be found that the sulfur fixation efficiency η of the mixed desulfurizer in this embodiment can reach about 81%. η=S ₁ ×M ₁ /(S ₀ ×M ₀ )×100%. M ₀ and M ₁ are the mass of the sample before and after calcination, respectively, in g. S ₀ and S ₁ are the sulfur content of the sample before and after calcination (converted to the mass percentage of sulfur trioxide), respectively.

Comparative example 1

The structure of the desulfurization system provided in this comparative example is basically the same as that of Example 1, and the desulfurization method adopted is also similar to that of Example 1, the only difference being that only crushed waste steel slag particles are used as desulfurizer. The sulfur fixation efficiency of the desulfurizer in this comparative example is about 10%.

Comparative example 2

The structure of the desulfurization system provided in this comparative example is basically the same as that of Example 1, and the desulfurization method adopted is also similar to that of Example 1, the only difference being that only pulverized limestone and attapulgite clay are mixed as the desulfurizer. The sulfur fixation efficiency of the desulfurizer in this comparative example is about 53%.

Comparative example 3

The structure of the desulfurization system provided in this comparative example is basically the same as that of Example 1, and the desulfurization method adopted is also similar to that of Example 1, the only difference being that only pulverized waste steel slag is mixed with limestone as a desulfurizer. The sulfur fixation efficiency of the desulfurizer in this comparative example is about 42%.

Comparative example 4

The structure of the desulfurization system provided in this comparative example is basically the same as that of Example 1, and the desulfurization method adopted is also similar to that of Example 1, the only difference being that only pulverized waste steel slag particles are mixed with attapulgite clay as a desulfurizer. The sulfur fixation efficiency of the desulfurizer in this comparative example is about 25%.

Example 2 The desulfurization method of this example is basically the same as that of Example 1, except that the mass ratio of waste steel slag, clay and limestone in the mixed desulfurizer is 11:5:4. The sulfur fixation efficiency of the mixed desulfurizer in this embodiment is about 78%.

Example 3 The desulfurization method of this example is basically the same as that of Example 1, except that the mass ratio of waste steel slag, clay and limestone in the mixed desulfurizer is 9:6:5. The sulfur fixation efficiency of the mixed desulfurizer in this embodiment is about 80%.

In addition, the hardness and compressive strength of cement products and bricks and tiles prepared by using the desulfurization products of Examples 1-3 are more than 20% higher than those of ordinary cement products and bricks and tiles.

In this application, steel slag, clay and limestone are used as raw materials, dried, pulverized, mixed in proportion, and then mixed with water to obtain a desulfurization slurry, and then the desulfurization slurry is used as an absorbent to realize wet flue gas desulfurization. It can be applied to the sulfur dioxide absorption treatment of thermal power plants, industrial coal-fired boilers and other flue gases containing sulfur dioxide. The desulfurization slurry can achieve the purpose of completely absorbing sulfur dioxide and other components in the flue gas, avoiding environmental pollution caused by a large amount of steel slag piled up, improving the environmental protection effect, and effectively saving resources at the same time. After absorbing the sulfur components in the flue gas, the desulfurization slurry can be subjected to precipitation and other treatments to separate the desulfurization products in it. These products can be used as building raw materials and have the advantages of low price and high strength.

It should be understood that the above-mentioned embodiments are only to illustrate the technical concept and features of the present application. The purpose is to enable those familiar with this technology to understand the content of the present application and implement it accordingly, and not to limit the protection scope of the present application. All equivalent changes or modifications made according to the spirit of the present application shall fall within the protection scope of the present application.

Claims (10)

1. A mixed desulfurizer, characterized in that it includes 45wt%-55wt% waste steel slag, 25wt%-35wt% clay and 15wt%-25wt% limestone. 2. The mixed desulfurizer according to claim 1, characterized in that: the waste steel slag, clay, and limestone are all granular, and the particle size is below 100 mesh. 3. The mixed desulfurizer according to claim 1 or 2, characterized in that the clay comprises attapulgite clay. 4. A desulfurization slurry, characterized in that it comprises the mixed desulfurization agent according to any one of claims 1-3 and water, and the solid content of the desulfurization slurry is 10wt%-15wt%, and the pH value is above 8.5. 5. A steel slag mixed with clay and limestone pulping desulfurization method, characterized in that it comprises: (1) After removing impurities and pulverizing waste steel slag, clay and limestone, and then uniformly mixing, the mixed desulfurizer described in any one of claims 1-3 is obtained; (2) uniformly mixing the mixed desulfurizing agent prepared in step (1) with water to make the desulfurization slurry described in claim 4; (3) Fully contacting the sulfur-containing flue gas with the desulfurization slurry prepared in step (2) to realize the desulfurization treatment of the sulfur-containing flue gas. 6. The desulfurization method for mixing steel slag with clay and limestone according to claim 5, characterized in that it specifically comprises: (1) Carry out impurity removal treatment on waste steel slag, clay, and limestone, and then perform drying and crushing treatment in sequence, and then uniformly mix the obtained waste steel slag particles, clay particles, and limestone particles to prepare a mixed desulfurizer; (2) uniformly mixing the mixed desulfurizer and water in the reaction tower to make the desulfurization slurry; (3) The sulfur-containing flue gas is input into the reaction tower from the lower part of the reaction tower, so that the sulfur-containing flue gas and the desulfurization slurry are fully contacted and reacted in the reaction tower, so that at least part of the sulfur-containing flue gas contains The sulfur component is removed, and then the flue gas after desulfurization treatment is discharged from the flue gas discharge port of the reaction tower; Wherein, the sulfur-containing component includes sulfur dioxide. 7. The desulfurization method for mixing steel slag with clay and limestone according to claim 6, characterized in that there are multiple reaction towers, and the step (3) also includes: making sulfur-containing flue gas flow from multiple Pass through the reaction towers in turn, and fully contact and react with the desulfurization slurry in each reaction tower until the composition of the flue gas reaches the emission standard, and then discharge the flue gas from the flue gas outlet of the last reaction tower to the atmosphere . 8. The desulfurization method for mixing steel slag with clay and limestone according to claim 6, characterized in that step (3) further comprises: when the pH value of the desulfurization slurry in the reaction tower is reduced to 4-5, then The desulfurization slurry is discharged to the waste liquid pool as waste liquid, and the desulfurization slurry with a pH value above 8.5 is re-introduced into the reaction tower. 9. The desulfurization method for mixing steel slag with clay and limestone according to any one of claims 6-8, characterized in that step (3) also includes: setting an agitator in the reaction tower to fully stir Desulfurization slurry in the reaction tower. 10. The desulfurization method for mixing steel slag with clay and limestone according to claim 8, characterized in that it also includes: separating the solid phase in the waste liquid, then drying it, and then applying it to the preparation of building Material.

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