Method for reducing the content of highly active CaO in steelmaking slag

Abstract

A method for reducing the content of high-activity CaO in steelmaking slag is disclosed, comprising the steps of: heating steelmaking slag to 200-500°C, adding it to a high-pressure reactor, introducing water mist and CO2 gas into the reactor, and reacting the CaO in the steelmaking slag with the water mist and CO2; crushing the steelmaking slag after the reaction, adding the crushed steelmaking slag to a particle size of 5-20 mm to a conical barrel, dehydrating it by high-speed steam suction under negative pressure, and then finely pulverizing it to a particle size of less than 5 mm. Adding this finely pulverized steelmaking slag to Isamil, adding desulfurization wastewater from sintering flue gas to Isamil, and introducing high-temperature steam and CO2 gas for further fine pulverization to obtain fine-grained steelmaking slag. This method effectively reduces the content of high-activity CaO in steelmaking slag and significantly improves the reliability of the subsequent steelmaking slag reuse.

Description

[Technical Field]

[0001] The present invention relates to the technical field of comprehensive resource recycling, and specifically to a method for reducing the content of highly active CaO in steelmaking slag. [Background technology]

[0002] Steelmaking slag is a by-product of the steelmaking process, consisting of agglomerated ore and powder containing elements such as CaO, SiO2, and MgO. Because steelmaking slag is generated in large quantities, it has traditionally been disposed of by landfilling or by pulverizing it and adding a small amount to cement production. However, there are limits to how much can be processed, resulting in a large amount of slag that cannot be processed. Therefore, steelmaking slag is crushed and used as road construction material, or pulverized and reused as building material. However, the highly active CaO in steelmaking slag tends to expand when it absorbs water in the natural environment, which affects the stability of the slag's later performance, making it difficult to utilize steelmaking slag in a comprehensive manner. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, how to reduce the content of highly active CaO in steelmaking slag and improve the stability of the reuse of steelmaking slag as a subsequent resource has become a technical issue to be solved in this field. [Means for solving the problem]

[0004] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides: A step of heating steelmaking slag to 200 to 500 ° C and adding it to a high-pressure reactor, introducing water mist and CO2 gas into the high-pressure reactor, and reacting CaO in the steelmaking slag with the water mist and CO2, The water mist is sprayed from a nozzle, and the amount of water mist is controlled to 0.1 to 0.3 times the weight of the steelmaking slag. The pressure of the CO2 gas is controlled to 0.1 to 0.6 MPa, and the flow rate of the CO2 gas is controlled to 20 to 60 m 3Step (1), in which the amount of steelmaking slag is controlled to 1 / t / hour and the CO2 gas introduction time is controlled to 2-5 hours; The steelmaking slag after the reaction is crushed, and any steelmaking slag with a particle size of more than 20 mm is crushed again. The crushed steelmaking slag to a particle size of 5 to 20 mm is added to a conical barrel and dehydrated by high-speed steam suction under negative pressure. The crushed steelmaking slag is then finely pulverized to a particle size of less than 5 mm. This steelmaking slag finely pulverized to a particle size of less than 5 mm and the finely pulverized steelmaking slag (steelmaking slag finely pulverized to a particle size of less than 5 mm by only crushing and crushing) are mixed and added to an Isamil (agitating mill). Desulfurization wastewater from the sintering flue gas is added to the Isamil, and high-temperature steam and CO2 gas are introduced to further crush the slag. The treated steelmaking slag slurry is discharged from the outlet of the Isamil to obtain dehydrated fine-grained steelmaking slag. The negative pressure in the conical barrel is controlled at 0.3-0.8Mpa, the airflow velocity at the bottom outlet of the conical barrel is controlled at 40-120m / s, and the flow rate of CO2 gas is controlled at 90-130m / s. 3 and (2) controlling the content of highly active CaO in steelmaking slag at a rate of 0.074 mm / ton of steelmaking slag per hour, the CO2 gas introduction time to be 0.2 to 0.8 hours, the temperature of the isamyl pulp to be higher than 40°C, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steelmaking slag to be greater than 90%.

[0005] Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of crushing the steelmaking slag after reaction, the proportion of the steelmaking slag with a particle size of less than 3 mm is controlled to 75% or more.

[0006] Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 55 m / s. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 65 m / s. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 75 m / s. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 85 m / s. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the process of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 95 m / s.

[0007] Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the step of performing dehydration treatment by high-speed steam suction under negative pressure, the negative pressure in the conical barrel is controlled to 0.4 MPa. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the step of performing dehydration treatment by high-speed steam suction under negative pressure, the negative pressure in the conical barrel is controlled to 0.5 MPa. Furthermore, in the above-mentioned method for reducing the content of highly active CaO in steelmaking slag, in the step of performing dehydration treatment by high-speed steam suction under negative pressure, the negative pressure in the conical barrel is controlled to 0.6 MPa.

[0008] Furthermore, in the method for reducing the content of high-activity CaO in the steelmaking slag, the steelmaking slag has the following components: TFe (total iron) 1 to 7 wt%, CaO 42 to 57 wt%, SiO2 11 to 33 wt%, MgO 3 to 9 wt%, Al2O3 0.8 to 4.7 wt%, Cr 0.5 to 4.7 wt%, and Ni 0.03 to 0.15 wt%, and the steelmaking slag is a block material with a particle size of 10 to 300 mm. [Effects of the Invention]

[0009] The method for reducing the content of high activity CaO in steelmaking slag of the present invention has the following advantages and beneficial effects: In this method, high-temperature steelmaking slag is added to a high-pressure reactor, and water and CO2 gas are introduced to react. The resulting steelmaking slag is then mechanically crushed and sized. Steelmaking slag with particle sizes larger than 20 mm is crushed again. The crushed steelmaking slag to particle sizes of 5 to 20 mm is placed in a conical barrel and dehydrated by high-speed steam suction under negative pressure. It is then finely crushed to particle sizes less than 5 mm. This finely crushed steelmaking slag is then mixed with the finely crushed steelmaking slag and added to Isamil. Water is then added, and high-temperature steam and CO2 gas are introduced for further fine crushing. Finally, finely crushed steelmaking slag is obtained. This effectively reduces the content of highly active CaO in the steelmaking slag, significantly improving the reliability of the subsequent steelmaking slag recycling process.

[0010] In order to more clearly describe the embodiments of the present invention or the technical solutions of the prior art, the following will briefly describe the drawings that need to be used in the description of the embodiments or the prior art. The drawings described in the following description are only some embodiments of the present invention, and it is obvious that those skilled in the art can derive other drawings from these drawings without any creative efforts. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic flow chart of the process of the method for reducing the content of high activity CaO in steelmaking slag according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below with reference to specific embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, and are not all of the embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without any creative efforts fall within the scope of protection of the present invention.

[0013] Generally, the method for reducing the content of high activity CaO in steelmaking slag of the present invention includes the following process steps: High-temperature steelmaking slag is added to a high-pressure reactor, and water mist and CO2 gas are introduced into the high-pressure reactor to cause the CaO in the steelmaking slag to react with the water mist and CO2 as follows: CaO + H2O = Ca(OH)2(1) Ca(OH)2 + CO2 = CaCO3 + H2O (2) Therefore, the content of highly active CaO in the steelmaking slag is effectively reduced.

[0014] After the reaction, the steelmaking slag is mechanically sized and crushed. After crushing, any steelmaking slag with a particle size larger than 20 mm is crushed again. The crushed steelmaking slag to a particle size of 5 to 20 mm is placed in a conical barrel and dehydrated by high-speed steam suction under negative pressure. The slag is then finely crushed to a particle size of less than 5 mm. This finely crushed steelmaking slag to a particle size of less than 5 mm is mixed with the finely crushed steelmaking slag and added to Isamil. Water is added, and high-temperature steam and CO2 gas are introduced to further crush the slag. Finally, finely crushed steelmaking slag is obtained.

[0015] Specifically, as shown in FIG. 1, the method for reducing the content of high activity CaO in steelmaking slag of the present invention includes the following steps: (1) Steelmaking slag was heated to 200-500°C and added to a high-pressure reactor. Water mist and CO2 gas were introduced into the reactor, and the CaO in the steelmaking slag was reacted with the water mist and CO2. The amount of water in the water mist was controlled to 0.1-0.3 times the weight of the steelmaking slag, the pressure of the CO2 gas was controlled to 0.1-0.6 MPa, and the flow rate of the CO2 gas was controlled to 20-60 m3. 3 / ton steelmaking slag · time (i.e., the flow rate of CO2 gas is 20-60 m per ton steelmaking slag). 3 / hour), and the CO2 gas introduction time is controlled to 2 to 5 hours. (2) The steelmaking slag after reaction was crushed, and any steelmaking slag larger than 20 mm in particle size was crushed again. The crushed steelmaking slag to particle sizes of 5 to 20 mm was added to a conical barrel and dehydrated by high-speed steam suction under negative pressure. It was then finely crushed to particle sizes less than 5 mm. The finely crushed steelmaking slag and the crushed steelmaking slag to particle sizes less than 5 mm were mixed and added to the Isamil. Desulfurization wastewater from sintering flue gas was added to the Isamil, and high-temperature steam and CO2 gas were introduced for further fine crushing. The processed steelmaking slag slurry was discharged from the outlet of the Isamil, yielding dehydrated fine-grained steelmaking slag. The negative pressure in the conical barrel was controlled to 0.3 to 0.8 MPa, the airflow velocity at the bottom outlet of the conical barrel was controlled to 40 to 120 m / s, and the CO2 gas flow rate was 90 to 130 m / s. 3 The CO2 gas introduction time is controlled to 0.2-0.8 hours, the temperature of the isamil pulp is controlled to be higher than 40°C, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steelmaking slag is controlled to be greater than 90%.

[0016] Furthermore, in one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the proportion of the fraction of the steelmaking slag having a particle size of less than 3 mm is controlled to 75% or more in the step of crushing the steelmaking slag after reaction.

[0017] In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 55 m / s. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the air velocity at the bottom outlet of the conical barrel is controlled to 65 m / s in the dehydration treatment step using high-speed steam suction under negative pressure. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 75 m / s. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 85 m / s. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 95 m / s.

[0018] In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the negative pressure in the conical barrel is controlled to 0.4 MPa in the dehydration treatment step using high-speed steam suction under negative pressure. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the negative pressure in the conical barrel is controlled to 0.5 MPa in the dehydration treatment step using high-speed steam suction under negative pressure. In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the negative pressure in the conical barrel is controlled to 0.6 MPa in the dehydration treatment step using high-speed steam suction under negative pressure.

[0019] In one specific embodiment, in the method of the present invention for reducing the content of highly active CaO in steelmaking slag, the steelmaking slag contains 1 to 7 weight percent TFe, 42 to 57 weight percent CaO, 11 to 33 weight percent SiO, 3 to 9 weight percent MgO, 0.8 to 4.7 weight percent AlO, 0.5 to 4.7 weight percent Cr, and 0.03 to 0.15 weight percent Ni, and the steelmaking slag is a chunk material having a particle size of 10 to 300 mm.

[0020] The method for reducing the content of highly active CaO in steelmaking slag according to the present invention will be described in detail below with reference to a standard example in the prior art and specific examples 1 to 7 of the present invention. Standard Example (Standard Example of Prior Art) In the prior art, the usual method for reducing the content of high activity CaO in steelmaking slag specifically includes the following production steps: (1) The raw materials were prepared, and 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at the steelworks of Taigang Corporation (Shanxi Taigang Stainless Steel Co., Ltd.). Its composition was 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor. The amount of water was 15 tons, and the water was injected from the top of the high-pressure reactor. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time of steelmaking slag with water and CO2 gas is 2.5 hours. (3) Crushing was performed. After the steelmaking slag was mechanically crushed and finely pulverized, the proportion of the particles in the steelmaking slag with a particle size of less than 0.074 mm was 91.3%. As a result, fine-grained steelmaking slag was obtained. Chemical analysis showed that when steelmaking slag was treated using conventional methods to reduce the content of high-activity CaO in the slag, the content of high-activity CaO in the slag was 8.3%, which was relatively high.

[0021] Example 1 In Example 1 of the present invention, when processing steelmaking slag, high-temperature steelmaking slag is placed in a high-pressure reactor, and water and CO2 gas are introduced to cause a reaction. The steelmaking slag after the reaction is then mechanically sized and crushed. After crushing, steelmaking slag with a particle size larger than 20 mm is crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm is placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure. The slag is then finely crushed to a particle size of less than 5 mm. This steelmaking slag crushed to a particle size of less than 5 mm and the steelmaking slag that has been crushed and re-crushed to a particle size of less than 5 mm are mixed together and added to Isamil. Water is added, and high-temperature steam and CO2 gas are introduced to further crush the slag. Finally, fine-grained steelmaking slag is obtained.

[0022] The method for reducing the content of high activity CaO in steelmaking slag in Example 1 of the present invention includes the following specific steps: (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 92.9% by weight was obtained. The negative pressure in the conical barrel is 0.4Mpa, the air velocity at the bottom outlet of the conical barrel is 55m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high activity CaO in steelmaking slag according to Example 1 of the present invention, the content of high activity CaO in the steelmaking slag was 5.1% by weight.

[0023] Example 2 In Example 2 of the present invention, the air velocity at the bottom outlet of the conical barrel is increased based on Example 1. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 2 of the present invention includes the following specific steps:

[0024] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag (hours), and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 93.2% by weight was obtained. The negative pressure in the conical barrel was 0.4 MPa, the air velocity at the bottom outlet of the conical barrel was 65 m / s, and the flow rate of CO2 gas was 100 m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high activity CaO in steelmaking slag according to Example 2 of the present invention, the content of high activity CaO in the steelmaking slag was 4.8 wt%.

[0025] Example 3 In Example 3 of the present invention, the air velocity at the bottom outlet of the conical barrel is further improved based on Example 2. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 3 of the present invention includes the following specific steps:

[0026] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 92.5% by weight was obtained. The negative pressure in the conical barrel is 0.4Mpa, the air velocity at the bottom outlet of the conical barrel is 75m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high-activity CaO in steelmaking slag according to Example 3 of the present invention, the content of high-activity CaO in the steelmaking slag was 4.5 wt%.

[0027] Example 4 In Example 4 of the present invention, the air velocity at the bottom outlet of the conical barrel is further improved based on Example 3. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 4 of the present invention includes the following specific steps:

[0028] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 93.0% by weight was obtained. The negative pressure in the conical barrel is 0.4Mpa, the air velocity at the bottom outlet of the conical barrel is 85m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high-activity CaO in steelmaking slag according to Example 4 of the present invention, the content of high-activity CaO in the steelmaking slag was 4.2 wt%.

[0029] Example 5 In Example 5 of the present invention, the air velocity at the bottom outlet of the conical barrel is further improved based on Example 4. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 5 of the present invention includes the following specific steps:

[0030] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 92.6% by weight was obtained. The negative pressure in the conical barrel is 0.4Mpa, the air velocity at the bottom outlet of the conical barrel is 95m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high-activity CaO in steelmaking slag according to Example 5 of the present invention, the content of high-activity CaO in the steelmaking slag was 4.1% by weight.

[0031] Example 6 In Example 6 of the present invention, the negative pressure in the conical barrel is further increased based on Example 5. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 6 of the present invention includes the following specific steps:

[0032] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) After the reaction, the steelmaking slag was crushed using a mechanical device. After crushing, the steelmaking slag with a particle size larger than 20 mm was crushed again. The crushed steelmaking slag to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure. The slag was then finely crushed to a particle size of less than 5 mm. This finely crushed steelmaking slag was mixed with the finely crushed steelmaking slag and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil. Dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 93.0% by weight was obtained. The negative pressure in the conical barrel is 0.5Mpa, the air velocity at the bottom outlet of the conical barrel is 95m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high-activity CaO in steelmaking slag according to Example 6 of the present invention, the content of high-activity CaO in the steelmaking slag was 3.9 wt%.

[0033] Example 7 In Example 7 of the present invention, the negative pressure in the conical barrel is further increased based on Example 6. Specifically, the method for reducing the content of high activity CaO in steelmaking slag in Example 7 of the present invention includes the following specific steps:

[0034] (1) 100 tons of high-temperature steelmaking slag was placed in a high-pressure reactor. The steelmaking slag was produced at Taishan Steel Corporation's steelworks and consisted of 3.62 wt% TFe, 56.12 wt% CaO, 21.37 wt% SiO2, 7.87 wt% MgO, 4.17 wt% Al2O3, 2.28 wt% Cr, and 0.12 wt% Ni. The steelmaking slag was in the form of chunks with a particle size of 10 to 300 mm, and the temperature of the steelmaking slag was 310°C. (2) Water and CO2 were introduced into the high-pressure reactor and reacted with the highly active CaO in the steelmaking slag. The amount of water was 15 tons, and the water was sprayed from the top of the high-pressure reactor as a water mist from a nozzle. The pressure of the CO2 gas was 0.4 MPa, and the flow rate was 55 m 3 / ton steelmaking slag·hour, and the reaction time between steelmaking slag and CO2 gas is 2.5 hours. (3) The steelmaking slag after the reaction was crushed using a mechanical device, and steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure, after which it was finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Desulfurization wastewater from sintering flue gas was added to Isamil, and high-temperature steam and CO2 gas were introduced to further crush the steelmaking slag. The steelmaking slag was retained in Isamil for 1.7 hours, after which the steelmaking slag slurry was discharged from the outlet of Isamil, and dehydrated fine-grained steelmaking slag with a particle size of less than 0.074 mm of 92.8% by weight was obtained. The negative pressure in the conical barrel is 0.6Mpa, the air velocity at the bottom outlet of the conical barrel is 95m / s, and the flow rate of CO2 gas is 100m 3 The CO2 gas introduction time is 0.4 hours, and the temperature of the isamil pulp is 45°C. Chemical analysis showed that when treated with the method of reducing the content of high-activity CaO in steelmaking slag according to Example 7 of the present invention, the content of high-activity CaO in the steelmaking slag was 3.8% by weight.

[0035] As a result of comparing Examples 1 to 7 of the present invention with the standard example, High-temperature steelmaking slag was added to a high-pressure reactor, and water and CO2 gas were introduced to cause a reaction. The steelmaking slag after the reaction was mechanically sized and crushed. Steelmaking slag with a particle size larger than 20 mm after crushing was crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm was placed in a conical barrel and dehydrated using high-speed steam suction under negative pressure. It was then finely crushed to a particle size of less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag were mixed and added to Isamil. Water was added, and high-temperature steam and CO2 gas were introduced to further crush the slag. Finally, fine-grained steelmaking slag was obtained. In Example 1 of the present invention, the content of highly active CaO in the steelmaking slag was 5.1 wt%, which was a significant decrease of 3.2% from the 8.3 wt% in the standard example.

[0036] In Example 2 of the present invention, the air velocity at the bottom outlet of the conical barrel was increased from 55 m / s to 65 m / s based on Example 1. The content of highly active CaO in the steelmaking slag was 4.8 wt%, which was 0.3% lower than that in Example 1. In Example 3 of the present invention, the air velocity at the bottom outlet of the conical barrel was increased from 65 m / s to 75 m / s based on Example 2. The content of highly active CaO in the steelmaking slag was 4.5 wt%, which was 0.3% lower than that in Example 2. In Example 4 of the present invention, the air velocity at the bottom outlet of the conical barrel was increased from 75 m / s to 85 m / s based on Example 3. The content of highly active CaO in the steelmaking slag was 4.2 wt%, which was 0.3% lower than that in Example 3. In Example 5 of the present invention, the air velocity at the bottom outlet of the conical barrel was increased from 85 m / s to 95 m / s based on Example 4. The content of highly active CaO in the steelmaking slag was 4.1 wt%, which was 0.1% lower than that in Example 4, indicating a significant decrease.

[0037] Based on Example 5, in Example 6 of the present invention, the negative pressure in the conical barrel was increased from 0.4 MPa to 0.5 MPa. The content of highly active CaO in the steelmaking slag was 3.9 wt%, which was 0.2% lower than that in Example 5. In Example 7 of the present invention, in which the negative pressure in the conical barrel was increased from 0.5 MPa to 0.6 MPa based on Example 6, the content of highly active CaO in the steelmaking slag was 3.8 wt%, which was 0.1% lower than that in Example 6, indicating a significant decrease.

[0038] As described above, compared with the prior art, the method for reducing the content of high activity CaO in steelmaking slag according to the present invention has the following advantages and beneficial effects. In this invention, high-temperature steelmaking slag is added to a high-pressure reactor, and water and CO2 gas are introduced to react. The reacted steelmaking slag is then mechanically crushed and sized. Steelmaking slag with particle sizes larger than 20 mm is crushed again. The crushed steelmaking slag to particle sizes of 5 to 20 mm is placed in a conical barrel and dehydrated by high-speed steam suction under negative pressure. It is then finely crushed to particle sizes less than 5 mm. This finely crushed steelmaking slag is then mixed with the finely crushed steelmaking slag and added to Isamil. Water is added, and high-temperature steam and CO2 gas are introduced for further fine crushing. Finally, finely crushed steelmaking slag is obtained. This effectively reduces the content of highly active CaO in the steelmaking slag, significantly improving the reliability of the steelmaking slag for subsequent recycling.

[0039] It should be noted that, as used herein, the terms "comprise," "contain," or any other variation thereof, are intended to cover a non-exclusive inclusion, whereby a process, method, article, or apparatus comprising a set of elements is intended to include not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0040] Furthermore, the above embodiments are only used to explain the technical solutions of the present invention, and do not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, it should be understood that those skilled in the art can modify the technical solutions described in the above embodiments or equally replace some technical features thereof, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A method for reducing the content of highly active CaO in steelmaking slag, comprising: Steelmaking slag is heated to 200 to 500°C and added to a high-pressure reactor. Water mist and CO ２ The CaO in the steelmaking slag was removed by introducing gas into the water mist and CO ２ reacting with The water mist is sprayed from a nozzle, and the amount of water in the water mist is controlled to 0.1 to 0.3 times the weight of the steelmaking slag. ２ The gas pressure is controlled to 0.1 to 0.6 MPa. ２ Gas flow rate is 20 to 60 m ３ / ton steelmaking slag. Controlled by time, CO ２ Step (1), in which the gas introduction time is controlled to 2 to 5 hours; The steelmaking slag after the reaction is crushed, and the steelmaking slag with a particle size of more than 20 mm after crushing is crushed again. The steelmaking slag crushed to a particle size of 5 to 20 mm is added to a conical barrel and subjected to a dehydration treatment using high-speed steam suction under negative pressure, and then finely crushed until the particle size is less than 5 mm. This steelmaking slag finely crushed to a particle size of less than 5 mm and the finely crushed steelmaking slag are mixed and added to Isamil. Desulfurization wastewater from sintering flue gas is added to Isamil, and high-temperature steam and CO are added. ２ A step of introducing gas, performing further fine pulverization treatment, and discharging the treated steelmaking slag slurry from the outlet of the Isamil to obtain dewatered fine-grained steelmaking slag, The negative pressure in the conical barrel was controlled to 0.3-0.8 MPa, and the air velocity at the bottom outlet of the conical barrel was controlled to 40-120 m / s. ２ Gas flow rate is 90 to 130 m ３ / ton steelmaking slag. Controlled by time, CO ２ and step (2) controlling the gas introduction time to 0.2 to 0.8 hours, the temperature of the isamil pulp to be higher than 40°C, and the proportion of the part with a particle size of less than 0.074 mm in the fine steelmaking slag to be higher than 90%.

2. A method for reducing the content of high activity CaO in steelmaking slag as described in claim 1, characterized in that in the process of crushing the steelmaking slag after reaction, the proportion of parts in the steelmaking slag with a particle size of less than 3 mm is controlled to 75% or more.

3. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 55 m / s.

4. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 65 m / s.

5. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 75 m / s.

6. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 85 m / s.

7. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the air velocity at the bottom outlet of the conical barrel is controlled to 95 m / s.

8. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein the negative pressure in the conical barrel is controlled to 0.4 MPa in the dehydration treatment by high-speed steam suction under negative pressure.

9. 2. The method for reducing the content of high activity CaO in steelmaking slag according to claim 1, wherein in the step of dehydration treatment by high-speed steam suction under negative pressure, the negative pressure in the conical barrel is controlled to 0.5 MPa.

10. 2. The method for reducing the content of highly active CaO in steelmaking slag according to claim 1, wherein the negative pressure in the conical barrel is controlled to 0.6 MPa in the dehydration treatment by high-speed steam suction under negative pressure.

11. The components of the steelmaking slag are 1 to 7 wt% TFe, 42 to 57 wt% CaO, SiO ２ 11-33% by weight, MgO 3-9% by weight, Al ２ O ３ 11. The method for reducing the content of high activity CaO in steelmaking slag according to claim 1, wherein the steelmaking slag has a particle size of 10 to 300 mm and contains 0.8 to 4.7 wt. %, 0.5 to 4.7 wt. % of CaO, and 0.03 to 0.15 wt. % of Ni, and the steelmaking slag is a lump material having a particle size of 10 to 300 mm.

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