Method for improving carbon sequestration and mineralization efficiency of hot steel slag

Abstract

The invention provides a method for improving the carbon sequestration and mineralization efficiency of hot steel slag, and belongs to the technical field of ferrous metallurgy. The method provided by the invention comprises the following steps: mixing steel slag with a reinforcing agent to obtain a mixture; spraying secondary wastewater of the iron and steel enterprises to the flue gas to humidify the flue gas; mixing the mixture with the humidified flue gas, and then carrying out a reaction; the reinforcing agent is manganese powder; the manganese powder accounts for 0.1%-1.5% of the steel slag in percentage by mass. On the basis of the steel slag carbon sequestration method, secondary wastewater of iron and steel enterprises is utilized, the water content of flue gas is controlled, the thermal-state steel slag carbon sequestration mineralization efficiency is improved, the method is simple in production process, safe to operate and easy to implement, meanwhile, the mineralization efficiency is improved, steel slag waste heat recovery is achieved, and the method has great significance in practical application.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a method for improving the efficiency of hot steel slag carbon fixation mineralization. Background Art

[0002] Steel slag is a byproduct of the steel production process caused by the oxidation of impurities in pig iron. It usually contains basic oxides such as calcium oxide (CaO) and magnesium oxide (MgO). Due to their high reactivity, these components are considered ideal raw materials for CO2 sequestration. At the same time, my country's steel production has been stable in the world's first row all year round, and crude steel production has reached more than half of the world's total production. However, steel slag is an industrial byproduct that is difficult to handle in my country's smelters, accounting for about 20% of crude steel production. Therefore, it is of great practical significance to develop methods to improve the efficiency of hot steel slag carbon fixation mineralization.

[0003] Patent CN118239702A discloses a process for recovering sensible heat of steel slag and fixing carbon. The steel slag melt is cast through a casting device. The outer shell of the cast high-temperature steel slag casting is solid and the inner core is liquid. The steel slag casting enters the vertical reactor from the upper feed port of the vertical reactor, and metallurgical flue gas is introduced from the air intake pipe at the bottom of the vertical reactor. The metallurgical flue gas exchanges heat with the high-temperature steel slag casting during the flow process to form high-temperature flue gas. At the same time, the high-temperature steel slag casting reacts with CO in the flue gas to fix carbon on the steel slag casting. The patent mainly proposes that the components utilize the sensible heat energy of steel slag, and the metallurgical flue gas in the reactor exchanges heat and fixes carbon with the steel slag casting. Patent CN118267851A discloses a method for carbon fixation by modifying steel slag with sintering machine head ash, which mainly involves first crushing and screening the steel slag to obtain steel slag powder, then grinding the steel slag powder and sintering machine head ash in a certain ratio to obtain modified steel slag powder, and finally using the modified steel slag powder for direct carbon fixation. This patent focuses on modifying steel slag with sintering machine head ash to improve the carbon fixation capacity of steel slag. In summary, the current method of improving the carbon fixation mineralization efficiency of hot steel slag mainly focuses on improving raw material performance or stabilizing indicators. However, the important role of flue gas moisture content in improving the carbon fixation mineralization efficiency of hot steel slag has been ignored. This key factor has great potential in improving the carbon fixation mineralization efficiency, but it has not yet been fully utilized. Summary of the invention

[0004] Based on the above content, the purpose of the present invention is to provide a method for improving the carbon fixation mineralization efficiency of hot steel slag. The present invention is based on the steel slag carbon fixation method, utilizes the secondary wastewater of steel enterprises, controls the water content of flue gas, and realizes the improvement of the carbon fixation mineralization efficiency of hot steel slag. The method has a simple production process, safe operation, and is easy to implement. At the same time, it improves the mineralization efficiency and realizes the recovery of steel slag waste heat, which is of great significance for practical application.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a method for improving the efficiency of hot steel slag carbon fixation mineralization, comprising the following steps:

[0007] Mixing steel slag with a reinforcing agent to obtain a mixture; spraying secondary wastewater from a steel enterprise into the flue gas to humidify the flue gas; mixing the mixture with the humidified flue gas and reacting the mixture;

[0008] The reinforcing agent is manganese powder; the mass percentage of the manganese powder in the steel slag is 0.1% to 1.5%.

[0009] The second technical solution of the present invention is a device for implementing the above method for improving the efficiency of hot steel slag carbon fixation mineralization, comprising a water diversion pipe 1, a water storage tank 2, a water content monitor 5, a circulating pressure pump 3, a water pipe 4, a No. 1 water mist nozzle 6, a No. 2 water mist nozzle 7, a flue gas pipeline 8, a mineralization device 9 and a steel slag pipeline 10;

[0010] The distance between the outer edge of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 and the outer side wall of the mineralization device 9 is 3m-15m;

[0011] The No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are arranged in the opposite direction to the direction of the smoke in the smoke duct 8, wherein the axial angle α between the No. 1 water mist nozzle 6 and the smoke duct 8 is 15° to 30°, and the axial angle β between the No. 2 water mist nozzle 7 and the smoke duct 8 is 45° to 60°;

[0012] The pressures of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are both 120% to 140% of the flue gas duct pressure.

[0013] The present invention discloses the following technical effects:

[0014] (1) The method for improving the carbon fixation and mineralization efficiency of hot steel slag provided by the present invention uses the secondary wastewater of the steel enterprise to control the water content of the flue gas, conducts heat exchange mineralization, and fully utilizes the physical heat of the steel slag to achieve the effect of waste heat recovery. At the same time, it reduces the f-CaO content in the steel slag, improves the stability of the steel slag, and realizes carbon fixation of the steel slag. The steel slag after carbon fixation can be used for high added value, thereby improving the resource utilization level of the steel slag.

[0015] (2) The technical solution provided by the present invention can fully utilize the secondary wastewater of steel enterprises, and effectively utilize the hydrogen peroxide component therein. The oxygen generated by decomposition can increase the solubility of CO2 in the flue gas, promote the formation of calcium carbonate, and significantly improve the efficiency of carbon fixation. At the same time, it reduces the waste of water resources in the steel plant, protects the ecological environment, and has significant environmental and economic benefits.

[0016] (3) The method provided by the present invention has the advantages of high mineralization efficiency, high resource utilization rate, and high dephosphorization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention is a flow diagram of the method for improving the efficiency of hot steel slag carbon fixation mineralization, wherein: 1: water diversion pipe, 2: water storage tank, 3: circulation pressure pump, 4: water pipe, 5: water content monitor, 6: No. 1 water mist nozzle, 7: No. 2 water mist nozzle, 8: flue gas pipeline, 9: mineralization device, 10: steel slag pipeline. DETAILED DESCRIPTION

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] The present invention controls the water content of the flue gas to improve the carbon fixation mineralization efficiency on the basis of hot steel slag carbon fixation. The increase in the water content of the flue gas can better react with the free calcium oxide in the steel slag to produce Ca(OH)2, promote the generation of CaCO3, increase the reactivity of the steel slag, and thus improve the carbon fixation mineralization efficiency, and has the characteristics of high dephosphorization rate and high resource utilization rate.

[0025] Based on the above content, the present invention provides a method for improving the efficiency of hot steel slag carbon fixation mineralization, comprising the following steps:

[0026] Mixing steel slag with a reinforcing agent to obtain a mixture; spraying secondary wastewater from a steel enterprise into the flue gas to humidify the flue gas; mixing the mixture with the humidified flue gas and reacting the mixture;

[0027] The reinforcing agent is manganese powder; the mass percentage of the manganese powder in the steel slag is 0.1% to 1.5%.

[0028] In the present invention, the addition of Mn induces structural and electronic promotion effects, resulting in smaller particles of the CaO-based absorbent in the steel slag, higher dispersion and specific surface area, and the formation of some electron-rich O and Ca species, which ultimately improves the adsorption performance of CO2 in flue gas, thereby further improving the carbon fixation mineralization efficiency.

[0029] In some embodiments of the present invention, the particle size of the steel slag is 10 μm to 50 μm, preferably 10 μm to 20 μm, and the temperature of the steel slag is 650°C to 850°C.

[0030] In the present invention, the particle size of the steel slag affects the carbon fixation rate. As the particle size of the steel slag increases, the carbon fixation rate decreases sharply. In order to improve the carbon fixation rate, the present invention preferably sets the steel slag particle size to the above parameter range.

[0031] In some embodiments of the present invention, the volume content of CO2 in the flue gas is 12% to 25%.

[0032] The reason why the present invention sets the CO2 content in the flue gas to the above parameters is that CO2 is not less than 12% to ensure the carbonation effect of the steel slag, and is not higher than 25% to prevent the steel slag from having insufficient carbonation capacity.

[0033] In some embodiments of the present invention, the calcium ion concentration in the secondary wastewater of the steel enterprise is 0-500 mg / L, preferably 200-500 mg / L, the pH value is 7-9, and the hydrogen peroxide concentration is 0%-5%, preferably 3%-5%.

[0034] The present invention uses the secondary wastewater of steel enterprises to control the water content in the flue gas, and performs carbon fixation mineralization treatment on the hot steel slag, thereby effectively improving its carbon fixation mineralization efficiency. The free calcium oxide in the steel slag interacts with the water mist in the flue gas to generate Ca(OH)2, which further promotes the formation of CaCO3 and accelerates the mineralization reaction process of the steel slag.

[0035] In some embodiments of the present invention, the secondary wastewater of the steel enterprise is one or more of industrial wastewater from a steel plant, domestic wastewater from a steel plant, blast furnace gas condensate and flue gas washing wastewater.

[0036] In some embodiments of the present invention, after the humidification, the water content of the flue gas is 15wt% to 25wt%.

[0037] In the present invention, if the water content of the flue gas is too low, sufficient Ca(OH)2 cannot be generated to carbonate f-CaO, resulting in no promotion effect; if the water content of the flue gas is too high, a water film may be formed on the surface of the slag particles, hindering the contact between CO2 and the slag surface. If the contact between CO2 gas and CaO in the slag is suppressed, the CO2 gas cannot effectively diffuse to the surface of the slag particles, resulting in a decrease in mineralization efficiency.

[0038] The present invention also provides a device for implementing the method for improving the efficiency of hot steel slag carbon fixation mineralization described in the above technical solution, comprising a water diversion pipe 1, a water storage tank 2, a water content monitor 5, a circulating pressure pump 3, a water pipe 4, a No. 1 water mist nozzle 6, a No. 2 water mist nozzle 7, a flue gas pipeline 8, a mineralization device 9 and a steel slag pipeline 10;

[0039] The distance between the outer edge of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 and the outer side wall of the mineralization device 9 is 3m-15m;

[0040] The No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are arranged in the opposite direction to the direction of the smoke in the smoke duct 8, wherein the axial angle α between the No. 1 water mist nozzle 6 and the smoke duct 8 is 15° to 30°, and the axial angle β between the No. 2 water mist nozzle 7 and the smoke duct 8 is 45° to 60°;

[0041] The pressures of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are both 120% to 140% of the flue gas duct pressure.

[0042] The invention ensures that the water mist and the flue gas are fully mixed by reasonably adjusting the angle and pressure of the water mist nozzle, thereby enhancing the contact between the flue gas and the steel slag and improving the reaction effect.

[0043] In some embodiments of the present invention, the secondary wastewater of the steel enterprise is delivered to the water storage tank 2 through the water diversion pipe 1, and the water spraying amount is controlled according to the water content monitor 5, and the secondary wastewater of the steel enterprise is input into the water pipe 4 through the circulating pressure pump 3, and sprayed and humidified into the flue gas pipeline 8 through the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 respectively, and the flue gas after spraying and humidification reacts with the mixture in the steel slag pipeline 10 in the mineralization device 9 (such as Figure 1 shown).

[0044] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0045] Example 1

[0046] In this embodiment, the particle size of the steel slag is 17.1 μm, the temperature of the steel slag is 650° C. to 850° C., and the content of manganese powder is 1% of the mass of the steel slag; the calcium ion concentration in the industrial wastewater of the steel plant is 451.33 mg / L, the pH value is 7.3, and the hydrogen peroxide concentration is 2.19%.

[0047] The industrial wastewater from the steel plant is delivered to the water storage tank 2 through the water diversion pipe 1, and the water spraying amount is controlled according to the water content monitor 5. The industrial wastewater from the steel plant is input into the water pipe 4 through the circulating pressure pump 3, and sprayed and humidified into the flue gas pipe 8 through the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 respectively, so that the water content of the flue gas is 18%. The flue gas after spraying and humidification reacts with the mixture in the slag pipe 9 in the mineralization device; wherein the outer edge of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 is at a distance L of 9m from the outer side wall of the mineralization device 9, the axial angle α between the No. 1 water mist nozzle 6 and the flue gas pipe 8 is 15°, the axial angle β between the No. 2 water mist nozzle 7 and the flue gas pipe 8 is 45°, and the pressures of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are both 120% of the flue gas pipe pressure.

[0048] In this embodiment, the slag mineralization efficiency is 28.39%, and the f-CaO content is 1.89%.

[0049] Example 2

[0050] In this embodiment, the particle size of the steel slag is 15.3 μm, the temperature of the steel slag is 650° C. to 850° C., and the content of manganese powder is 0.5% of the mass of the steel slag; the calcium ion concentration in the industrial wastewater of the steel plant is 383.71 mg / L, the pH value is 7.9, and the hydrogen peroxide concentration is 2.59%.

[0051] The industrial wastewater from the steel plant is delivered to the water storage tank 2 through the water diversion pipe 1, and the water spraying amount is controlled according to the water content monitor 5. The industrial wastewater from the steel plant is input into the water pipe 4 through the circulating pressure pump 3, and sprayed and humidified into the flue gas pipe 8 through the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 respectively, so that the water content of the flue gas is 20%. The flue gas after spraying and humidification reacts with the mixture in the slag pipe 9 in the mineralization device; wherein the outer edge of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 is at a distance L of 6m from the outer side wall of the mineralization device 9, the axial angle α between the No. 1 water mist nozzle 6 and the flue gas pipe 8 is 20°, the axial angle β between the No. 2 water mist nozzle 7 and the flue gas pipe 8 is 50°, and the pressures of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are both 130% of the flue gas pipe pressure.

[0052] In this embodiment, the slag mineralization efficiency is 29.20%, and the f-CaO content is 1.64%.

[0053] Example 3

[0054] In this embodiment, the particle size of the steel slag is 20 μm, the temperature of the steel slag is 650° C. to 850° C., and the content of manganese powder is 1.5% of the mass of the steel slag; the calcium ion concentration in the industrial wastewater of the steel plant is 203.46 mg / L, the pH value is 8.5, and the hydrogen peroxide concentration is 4.22%.

[0055] The industrial wastewater from the steel plant is delivered to the water storage tank 2 through the water diversion pipe 1, and the water spraying amount is controlled according to the water content monitor 5. The industrial wastewater from the steel plant is input into the water pipe 4 through the circulating pressure pump 3, and sprayed and humidified into the flue gas pipe 8 through the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 respectively, so that the water content of the flue gas is 22%. The flue gas after spraying and humidification reacts with the mixture in the slag pipe 9 in the mineralization device; wherein the outer edge of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 is at a distance L of 12m from the outer side wall of the mineralization device 9, the axial angle α between the No. 1 water mist nozzle 6 and the flue gas pipe 8 is 25°, the axial angle β between the No. 2 water mist nozzle 7 and the flue gas pipe 8 is 55°, and the pressures of the No. 1 water mist nozzle 6 and the No. 2 water mist nozzle 7 are both 140% of the flue gas pipe pressure.

[0056] In this embodiment, the slag mineralization efficiency is 28.71%, and the f-CaO content is 1.70%.

[0057] Comparative Example 1

[0058] The hot steel slag carbon fixation method of this comparative example is the same as that of Example 1, except that the particle size of the steel slag is 85.4 μm.

[0059] In this comparative example, the slag mineralization efficiency is 9% and the f-CaO content is 5.28%.

[0060] Comparative Example 2

[0061] The hot steel slag carbon fixation method of this comparative example is the same as that of Example 1, the only difference being that the particle size of the steel slag is 204.4 μm.

[0062] In this comparative example, the slag mineralization efficiency is 5.4%, and the f-CaO content is 5.89%.

[0063] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving the efficiency of hot steel slag carbon fixation mineralization, characterized in that: The following steps are involved: Mixing steel slag with a reinforcing agent to obtain a mixture; spraying secondary wastewater from a steel enterprise into the flue gas to humidify the flue gas; mixing the mixture with the humidified flue gas and reacting the mixture; The reinforcing agent is manganese powder; the mass percentage of the manganese powder in the steel slag is 0.1% to 1.5%.

2. The method for improving the efficiency of hot steel slag carbon fixation mineralization according to claim 1, characterized in that: The particle size of the steel slag is 10 μm to 50 μm, and the temperature of the steel slag is 650° C. to 850° C.

3. The method for improving the efficiency of hot steel slag carbon fixation mineralization according to claim 1, characterized in that: The volume content of CO2 in the flue gas is 12% to 25%.

4. The method for improving the efficiency of hot steel slag carbon fixation mineralization according to claim 1, characterized in that: The calcium ion concentration in the secondary wastewater of the steel enterprise is 0-500 mg / L, the pH value is 7-9, and the hydrogen peroxide concentration is 0%-5%.

5. The method for improving the efficiency of hot steel slag carbon fixation mineralization according to claim 1 or 4, characterized in that: The secondary wastewater of the steel enterprise is one or more of industrial wastewater of the steel plant, domestic wastewater of the steel plant, blast furnace gas condensate and flue gas washing wastewater.

6. The method for improving the efficiency of hot steel slag carbon fixation mineralization according to claim 1, characterized in that: After the humidification, the water content of the flue gas is 15wt% to 25wt%.

7. A device for implementing the method for improving the efficiency of hot steel slag carbon fixation mineralization according to any one of claims 1 to 6, characterized in that: It comprises a water diversion pipe (1), a water storage tank (2), a water content monitor (5), a circulation booster pump (3), a water pipe (4), a No. 1 water mist nozzle (6), a No. 2 water mist nozzle (7), a flue gas pipe (8), a mineralization device (9) and a slag pipe (10); The outer edges of the No. 1 water mist nozzle (6) and the No. 2 water mist nozzle (7) are 3m-15m away from the outer side wall of the mineralization device (9); The No. 1 water mist nozzle (6) and the No. 2 water mist nozzle (7) are arranged in the opposite direction to the direction of the smoke in the smoke duct (8), wherein the axial angle α between the No. 1 water mist nozzle (6) and the smoke duct (8) is 15° to 30°, and the axial angle β between the No. 2 water mist nozzle (7) and the smoke duct (8) is 45° to 60°; The pressures of the No. 1 water mist nozzle (6) and the No. 2 water mist nozzle (7) are both 120% to 140% of the pressure of the smoke duct.

8. The device for implementing the method for improving the efficiency of hot steel slag carbon fixation mineralization according to any one of claims 1 to 6 according to claim 7, characterized in that: The secondary wastewater of the steel enterprise is transported to a water storage tank (2) through a water diversion pipe (1), and the water spraying amount is controlled according to a water content monitor (5). The secondary wastewater of the steel enterprise is input into a water pipe (4) through a circulating pressure pump (3), and sprayed and humidified into a flue gas pipe (8) through a No. 1 water mist nozzle (6) and a No. 2 water mist nozzle (7), respectively. The flue gas after spraying and humidification reacts with a mixed material in a slag pipe (10) in a mineralization device (9).

Images