Method for reducing content of high-activity cao in steel slag

Abstract

A method for reducing the content of high-activity CaO in steel slag, comprising: controlling the temperature of steel slag to be 200-500℃, putting same into a high-pressure reactor, and introducing atomized water and CO2 gas into the high-pressure reactor such that CaO in the steel slag reacts with the atomized water and CO2; crushing the reacted steel slag, wherein steel slag having a granular size of 5-20 mm after the crushing is added into a conical bucket to undergo negative-pressure high-speed water steam extraction dehydration treatment, and then fine milled until the granular size is less than 5 mm; and mixing the fine-milled steel slag with the steel slag having a granular size of less than 5 mm after the crushing, adding same to an Isa mill, adding desulfurization wastewater of sintering flue gas and introducing high-temperature steam and CO2 gas into the Isa mill, and carrying out further fine-milling treatment to obtain fine-grain steel slag. The method effectively reduces the content of high-activity CaO in the steel slag, thereby remarkably improving the stability of steel slag in following resource recycling.

Description

Method for reducing high-activity CaO content in steel slag Technical Field

[0001] The invention belongs to the technical field of comprehensive resource recycling, and particularly relates to a method for reducing the content of high-activity CaO in steel slag. Background Art

[0002] Steel slag is a byproduct of the steelmaking process within steel mills, consisting of large ore and powdery materials containing CaO, SiO2, MgO, and other components. Due to its large production volume, steel slag has traditionally been disposed of by landfill or by adding small amounts to cement during fine grinding. However, this limited processing capacity has left a significant amount of slag unprocessed. Consequently, secondary utilization has been pursued by crushing the slag as a road construction material or finely grinding it for use as a building material. However, the high activity of CaO in the slag, which readily expands upon absorbing water in the natural environment, affects the stability of the slag's subsequent performance, preventing its widespread and comprehensive utilization.

[0003] Therefore, how to reduce the content of high-activity CaO in steel slag to improve the stability of subsequent resource recycling of steel slag has become a technical problem that urgently needs to be solved in this field.

[0004] Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a method for reducing the high-activity CaO content in steel slag, comprising the following steps:

[0006] (1) After the steel slag is controlled to 200-500°C, it is added into a high-pressure reactor, and mist water and CO2 gas are introduced into the high-pressure reactor. CaO in the steel slag reacts with the mist water and CO2. The mist water is sprayed from a nozzle, and the amount of the mist water is controlled to be 0.1-0.3 times the weight of the steel slag. The pressure of the CO2 gas is controlled to be 0.1-0.6 MPa, and the flow rate of the CO2 gas is controlled to be 20-60 m 3 / ton of steel slag·hour, the CO2 gas flow time is controlled to be 2 to 5 hours;

[0007] (2) Crushing the steel slag after the reaction, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; adding the steel slag with a particle size of 5 to 20 mm after crushing into a conical barrel for negative pressure high-speed steam exhaust dehydration treatment, and then finely grinding it to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is controlled to be 0.3 to 0.8 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 40 to 120 m / s; mixing the finely ground steel slag with the steel slag with a particle size less than 5 mm after crushing and adding them together into the sand mill, adding sintering flue gas desulfurization wastewater into the sand mill, introducing high-temperature steam and CO2 gas for further fine grinding treatment, and the treated steel slag slurry is discharged from the outlet of the sand mill, and fine-grained steel slag is obtained after dehydration, wherein the flow rate of CO2 gas is controlled to be 90 to 130 m 3 / ton of steel slag·hour, the time of passing CO2 gas is controlled to be 0.2-0.8 hours, the temperature of the slurry ground by sand is controlled to be greater than 40°C, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is controlled to be greater than 90%.

[0008] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the crushing of the reacted steel slag, the proportion of the portion with a particle size of less than 3 mm in the steel slag is controlled to be above 75%.

[0009] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 55 m / s.

[0010] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 65m / s.

[0011] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 75m / s.

[0012] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 85 m / s.

[0013] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 95 m / s.

[0014] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.4 MPa.

[0015] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.5 MPa.

[0016] Furthermore, in the above method for reducing the high-activity CaO content in steel slag, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.6 MPa.

[0017] Furthermore, in the above-mentioned method for reducing the high-activity CaO content in steel slag, the components of the steel slag are as follows by weight: TFe = 1-7%, CaO = 42-57%, SiO2 = 11-33%, MgO = 3-9%, Al2O3 = 0.8-4.7%, Cr = 0.5-4.7%, Ni = 0.03-0.15%, and the steel slag is a block material with a particle size of 10-300 mm.

[0018] The method of reducing the high-activity CaO content in steel slag of the present invention has the following advantages and beneficial effects:

[0019] The present invention adds high-temperature steel slag into a high-pressure reactor, introduces water and CO2 gas to react, and then mechanically crushes the reacted steel slag into whole particles, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing, and the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, and the finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to an abrasive mill with water, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, to finally obtain fine-grained steel slag, wherein the content of high-activity CaO in the steel slag is effectively reduced, and the stability of subsequent resource recycling of the steel slag is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0021] FIG1 is a schematic diagram of the process flow of the method for reducing the high-activity CaO content in steel slag according to the present invention. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] In general, the method of reducing the high-activity CaO content in steel slag of the present invention comprises the following process steps:

[0024] Add high-temperature steel slag into a high-pressure reactor, introduce mist water and CO2 gas into the high-pressure reactor, and the CaO in the steel slag reacts with the mist water and CO2 as follows: CaO + H2O = Ca(OH)2 (1) Ca(OH)2 + CO2 = CaCO3 + H2O (2)

[0025] As a result, the content of high-activity CaO in steel slag can be effectively reduced;

[0026] The steel slag after the reaction is mechanically crushed into particles, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing. The steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size of less than 5 mm. The finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to an abrasive mill with water, and high-temperature steam and CO2 gas are introduced for further fine grinding to obtain fine-grained steel slag.

[0027] Specifically, as shown in FIG1 , the method for reducing the high-activity CaO content in steel slag of the present invention comprises the following steps:

[0028] (1) After the steel slag is heated to 200-500°C, it is added into a high-pressure reactor. Mist water and CO2 gas are introduced into the high-pressure reactor. CaO in the steel slag reacts with the mist water and CO2. The amount of mist water is controlled to be 0.1-0.3 times the weight of the steel slag, the pressure of CO2 gas is controlled to be 0.1-0.6 MPa, and the flow rate of CO2 gas is controlled to be 20-60 m 3 / ton of steel slag·hour (i.e. the flow rate of CO2 gas is based on 20~60m3 / ton of steel slag 3 / hour control), the time of CO2 gas passage is controlled to be 2 to 5 hours;

[0029] (2) Crushing the steel slag after the reaction, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; adding the steel slag with a particle size of 5 to 20 mm after crushing into a conical barrel for negative pressure high-speed steam exhaust dehydration treatment, and then finely grinding it to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is controlled to be 0.3 to 0.8 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 40 to 120 m / s; mixing the finely ground steel slag with the steel slag with a particle size less than 5 mm after crushing and adding them together into the sand mill, adding sintering flue gas desulfurization wastewater into the sand mill, introducing high-temperature steam and CO2 gas for further fine grinding treatment, and the treated steel slag slurry is discharged from the outlet of the sand mill, and fine-grained steel slag is obtained after dehydration, wherein the flow rate of CO2 gas is controlled to be 90 to 130 m 3 / ton of steel slag·hour, the time of passing CO2 gas is controlled to be 0.2-0.8 hours, the temperature of the slurry ground by sand is controlled to be greater than 40°C, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is controlled to be greater than 90%.

[0030] Furthermore, in the method for reducing the high-activity CaO content in steel slag of the present invention, during the crushing of the reacted steel slag, the proportion of the portion with a particle size of less than 3 mm in the steel slag is controlled to be above 75%.

[0031] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 55m / s.

[0032] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 65m / s.

[0033] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 75m / s.

[0034] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 85m / s.

[0035] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the air flow velocity at the outlet of the lower end of the conical barrel is controlled to be 95m / s.

[0036] As a specific embodiment, in the method for reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.4 MPa.

[0037] As a specific embodiment, in the method for reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.5 MPa.

[0038] As a specific embodiment, in the method for reducing the high-activity CaO content in steel slag of the present invention, during the negative pressure high-speed steam exhaust dehydration treatment, the negative pressure in the conical barrel is controlled to be 0.6 MPa.

[0039] As a specific embodiment, in the method of reducing the high-activity CaO content in steel slag of the present invention, the components of the steel slag are as follows by weight: TFe = 1-7%, CaO = 42-57%, SiO2 = 11-33%, MgO = 3-9%, Al2O3 = 0.8-4.7%, Cr = 0.5-4.7%, Ni = 0.03-0.15%, and the steel slag is a block material with a particle size of 10-300 mm.

[0040] The method for reducing the high-activity CaO content in steel slag of the present invention is described in detail below in combination with the benchmark example in the prior art and specific examples 1-7 of the present invention.

[0041] Benchmark Example

[0042] The conventional method for reducing the high-activity CaO content in steel slag in the prior art includes the following specific production steps:

[0043] (1) Raw material preparation: 100 tons of high-temperature steel slag is poured into the high-pressure reactor. The steel slag is the steel slag produced by the Taiyuan Iron and Steel Corporation Steel Plant. Its composition by weight is as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag is a lump with a particle size of 10 to 300 mm. The slag temperature is 310°C.

[0044] (2) Water and CO2 are introduced into the high-pressure reactor, wherein the amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor. The pressure of CO2 gas is 0.4Mpa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag, water and CO2 gas is 2.5 hours.

[0045] (3) Crushing: After the steel slag is mechanically crushed and finely ground, the proportion of the part with a particle size of less than 0.074 mm in the steel slag is 91.3%, thereby producing fine-grained steel slag.

[0046] According to the test results, after being treated according to the conventional method for reducing the high-activity CaO content in steel slag in the prior art, the high-activity CaO content in the steel slag is 8.3%, which is relatively high.

[0047] Example 1

[0048] When steel slag is treated using Example 1 of the present invention, high-temperature steel slag is added to a high-pressure reactor, water and CO2 gas are introduced to react, and then the reacted steel slag is mechanically crushed to form particles, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing, and the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size of less than 5 mm. The finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to a sand mill, water is added, and high-temperature steam and CO2 gas are introduced for further fine grinding to obtain fine-grained steel slag.

[0049] The method for reducing the high-activity CaO content in steel slag according to Example 1 of the present invention comprises the following specific steps:

[0050] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0051] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0052] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.4 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 55 m / s; the finely ground steel slag and the steel slag with a particle size less than 5 mm after crushing are mixed and added together to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45℃, the steel slag stays in the Aisha mill for 1.7 hours, and the steel slag slurry is discharged from the Aisha mill outlet. Fine-grained steel slag is obtained after dehydration, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is 92.9%.

[0053] After testing, it was found that the content of high-activity CaO in the steel slag was 5.1% after being treated according to the method for reducing the content of high-activity CaO in steel slag according to Example 1 of the present invention.

[0054] Example 2

[0055] In Example 2 of the present invention, based on Example 1, the velocity of the airflow at the outlet of the lower end of the conical barrel is increased. Specifically, the method of reducing the high-activity CaO content in steel slag in Example 2 of the present invention includes the following specific steps:

[0056] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0057] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0058] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.4 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 65 m / s; the finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45℃, and the steel slag stays in the Aisha mill for 1.7 hours. The steel slag slurry is discharged from the Aisha mill outlet and fine-grained steel slag is obtained after dehydration. The proportion of the fine-grained steel slag with a particle size of less than 0.074 mm is 93.2%.

[0059] After testing, it was found that the content of high-activity CaO in the steel slag was 4.8% after being treated according to the method for reducing the content of high-activity CaO in steel slag according to Example 2 of the present invention.

[0060] Example 3

[0061] In Example 3 of the present invention, based on Example 2, the velocity of the airflow at the outlet of the lower end of the conical barrel is further increased. Specifically, the method of reducing the high-activity CaO content in steel slag in Example 3 of the present invention includes the following specific steps:

[0062] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0063] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0064] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.4 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 75 m / s; the finely ground steel slag is mixed with the steel slag with a particle size less than 5 mm after crushing and then added to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45°C, the steel slag stays in the Aisha mill for 1.7 hours, and the steel slag slurry is discharged from the Aisha mill outlet. Fine-grained steel slag is obtained after dehydration, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is 92.5%.

[0065] After testing, it was found that the content of high-activity CaO in the steel slag was 4.5% after being treated according to the method for reducing the content of high-activity CaO in the steel slag according to Example 3 of the present invention.

[0066] Example 4

[0067] In Example 4 of the present invention, based on Example 3, the velocity of the airflow at the outlet of the lower end of the conical barrel is further increased. Specifically, the method of reducing the high-activity CaO content in steel slag in Example 4 of the present invention includes the following specific steps:

[0068] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0069] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0070] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.4 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 85 m / s; the finely ground steel slag is mixed with the steel slag with a particle size less than 5 mm after crushing and then added to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45°C, the steel slag stays in the Aisha mill for 1.7 hours, and the steel slag slurry is discharged from the Aisha mill outlet. Fine-grained steel slag is obtained after dehydration, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is 93.0%.

[0071] After testing, it was found that after being treated according to the method for reducing the content of high-activity CaO in steel slag in Example 4 of the present invention, the content of high-activity CaO in the steel slag was 4.2%.

[0072] Example 5

[0073] In Example 5 of the present invention, based on Example 4, the velocity of the airflow at the outlet of the lower end of the conical barrel is further increased. Specifically, the method of reducing the high-activity CaO content in steel slag in Example 5 of the present invention includes the following specific steps:

[0074] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0075] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0076] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.4 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 95 m / s; the finely ground steel slag is mixed with the steel slag with a particle size less than 5 mm after crushing, and then added together to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45℃, and the steel slag stays in the Aisha mill for 1.7 hours. The steel slag slurry is discharged from the Aisha mill outlet and fine-grained steel slag is obtained after dehydration. The proportion of the fine-grained steel slag with a particle size of less than 0.074 mm is 92.6%.

[0077] After testing, it was found that after being treated according to the method for reducing the content of high-activity CaO in steel slag in Example 5 of the present invention, the content of high-activity CaO in the steel slag was 4.1%.

[0078] Example 6

[0079] 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 high-activity CaO content in steel slag in Example 6 of the present invention includes the following specific steps:

[0080] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0081] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0082] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.5 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 95 m / s; the finely ground steel slag is mixed with the steel slag with a particle size less than 5 mm after crushing and then added to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45°C, the steel slag stays in the Aisha mill for 1.7 hours, and the steel slag slurry is discharged from the Aisha mill outlet. Fine-grained steel slag is obtained after dehydration, and the proportion of the part with a particle size of less than 0.074 mm in the fine-grained steel slag is 93.0%.

[0083] After testing, it was found that after being treated according to the method for reducing the high-activity CaO content in steel slag in Example 6 of the present invention, the content of high-activity CaO in the steel slag was 3.9%.

[0084] Example 7

[0085] In Example 7 of the present invention, based on Example 6, the negative pressure in the conical barrel is further increased. Specifically, the method for reducing the high-activity CaO content in steel slag in Example 7 of the present invention includes the following specific steps:

[0086] (1) 100 tons of high-temperature steel slag was poured into a high-pressure reactor. The steel slag was produced by the Taiyuan Iron and Steel Corporation steelmaking plant. Its composition by weight was as follows: TFe = 3.62%, CaO = 56.12%, SiO2 = 21.37%, MgO = 7.87%, Al2O3 = 4.17%, Cr = 2.28%, Ni = 0.12%. The steel slag was in the form of lumps with a particle size of 10 to 300 mm. The temperature of the steel slag was 310°C.

[0087] (2) Water and CO2 are introduced into the high-pressure reactor to react with the high-activity CaO in the steel slag. The amount of water is 15 tons, and the water is sprayed from the top of the high-pressure reactor in the form of mist sprayed by the nozzle. The pressure of the CO2 gas is 0.4 MPa and the flow rate is 55m 3 / ton of steel slag·hour, the reaction time of steel slag and CO2 gas is 2.5 hours.

[0088] (3) The steel slag after the reaction is crushed by mechanical equipment, and the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed steam exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, wherein the negative pressure in the conical barrel is 0.6 MPa, and the air flow velocity at the outlet of the lower end of the conical barrel is 95 m / s; the finely ground steel slag and the steel slag with a particle size less than 5 mm after crushing are mixed and added together to the sand mill, and sintering flue gas desulfurization wastewater is added to the sand mill, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, wherein the flow rate of CO2 gas is 100 m 3 / ton of steel slag·hour, the time for passing CO2 gas is 0.4 hour, the temperature of the slurry in the Aisha mill is 45℃, and the steel slag stays in the Aisha mill for 1.7 hours. The steel slag slurry is discharged from the Aisha mill outlet and fine-grained steel slag is obtained after dehydration. The proportion of the fine-grained steel slag with a particle size of less than 0.074 mm is 92.8%.

[0089] After testing, it was found that the content of high-activity CaO in the steel slag was 3.8% after treatment according to the method for reducing the content of high-activity CaO in the steel slag according to Example 7 of the present invention.

[0090] Comparing Examples 1-7 of the present invention with the reference example, it can be seen that:

[0091] In Example 1 of the present invention, high-temperature steel slag is added to a high-pressure reactor, water and CO2 gas are introduced to react, and then the reacted steel slag is mechanically crushed to form particles, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing, and the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, and the finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to an abrasive mill with water, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment to finally obtain fine-grained steel slag. The high-activity CaO content in the steel slag is 5.1%, which is 3.2 percentage points lower than 8.3% in the baseline embodiment, a significant reduction.

[0092] In Example 2 of the present invention, based on Example 1, the velocity of the air flow at the outlet of the lower end of the conical barrel is increased from 55 m / s to 65 m / s, and the high-activity CaO content in the steel slag is 4.8%, which is 0.3 percentage points lower than that of Example 1.

[0093] For Example 3 of the present invention, based on Example 2, the velocity of the air flow at the outlet of the lower end of the conical barrel is increased from 65 m / s to 75 m / s, and the high-activity CaO content in the steel slag is 4.5%, which is 0.3 percentage points lower than that of Example 2.

[0094] For Example 4 of the present invention, based on Example 3, the velocity of the air flow at the outlet of the lower end of the conical barrel is increased from 75 m / s to 85 m / s, and the high-activity CaO content in the steel slag is 4.2%, which is 0.3 percentage points lower than that of Example 3.

[0095] For Example 5 of the present invention, based on Example 4, the velocity of the air flow at the outlet of the lower end of the conical barrel is increased from 85 m / s to 95 m / s, and the high-activity CaO content in the steel slag is 4.1%, which is 0.1 percentage points lower than that of Example 4, and the reduction rate is reduced.

[0096] In Example 6 of the present invention, based on Example 5, the negative pressure in the conical barrel is increased from 0.4 MPa to 0.5 MPa, and the high-activity CaO content in the steel slag is 3.9%, which is 0.2 percentage points lower than that in Example 5.

[0097] In Example 7 of the present invention, based on Example 6, the negative pressure in the conical barrel is increased from 0.5 MPa to 0.6 MPa, and the high-activity CaO content in the steel slag is 3.8%, which is 0.1 percentage points lower than that in Example 6, and the reduction rate is reduced.

[0098] In summary, compared with the prior art, the method of reducing the high-activity CaO content in steel slag of the present invention has the following advantages and beneficial effects:

[0099] The present invention adds high-temperature steel slag into a high-pressure reactor, introduces water and CO2 gas to react, and then mechanically crushes the reacted steel slag into whole particles, wherein the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing, and the steel slag with a particle size of 5 to 20 mm after crushing is added to a conical barrel for negative pressure high-speed water vapor exhaust dehydration treatment, and then finely ground to a particle size less than 5 mm, and the finely ground steel slag and the crushed steel slag with a particle size less than 5 mm are mixed and added together to an abrasive mill with water, and high-temperature steam and CO2 gas are introduced for further fine grinding treatment, to finally obtain fine-grained steel slag, wherein the content of high-activity CaO in the steel slag is effectively reduced, and the stability of subsequent resource recycling of the steel slag is significantly improved.

[0100] It should be noted that, in this document, unless otherwise expressly specified or limited, the term "connected" or its synonyms should be interpreted broadly. For example, "connected" can mean a fixed or removable connection; a mechanical or electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication between two elements or the interaction between two elements. A person of ordinary skill in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances. Furthermore, expressions such as "first" and "second" are used solely to distinguish one entity or operation from another and do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, the terms "include," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Furthermore, the terms "front," "rear," "left," "right," "upper," and "lower" herein are used with reference to the positions shown in the accompanying drawings.

[0101] It should also be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, 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 steel slag, characterized in that, it includes the following steps: (1) After controlling the steel slag to 200 - 500 °C, add it into a high-pressure reactor, and introduce atomized water and CO into the high-pressure reactor. 2 The CaO in the steel slag reacts with the atomized water and CO. 2 Among them, the atomized water is sprayed in by a nozzle, and the amount of the atomized water is controlled to be 0.1 - 0.3 times the weight of the steel slag. The pressure of the CO 2 gas is controlled to be 0.1 - 0.6 Mpa, and the flow rate of the CO 2 gas is controlled to be 20 - 60 m 3 / ton of steel slag·hour. The time for introducing the CO 2 gas is controlled to be 2 - 5 hours. (2) Crush the reacted steel slag. Among them, the steel slag with a particle size greater than 20 mm after crushing is returned for re-crushing; the steel slag with a particle size of 5 - 20 mm after crushing is added into a conical barrel for negative pressure high-speed water vapor suction dehydration treatment, and then finely ground to a particle size less than 5 mm. Among them, the negative pressure in the conical barrel is controlled at 0.3 - 0.8 Mpa, and the air flow velocity at the lower outlet of the conical barrel is controlled at 40 - 120 m / s; Mix the finely ground steel slag with the steel slag with a particle size less than 5 mm after crushing and add them together into an Aisha mill. Add sintered flue gas desulfurization wastewater into the Aisha mill, introduce high-temperature steam and CO 2 gas for further fine grinding treatment. The treated steel slag slurry is discharged from the outlet of the Aisha mill, and fine-grained steel slag is obtained after dehydration. Among them, the flow rate of CO 2 gas is controlled at 90 - 130 m 3 / ton of steel slag·hour, the time for introducing CO 2 gas is controlled at 0.2 - 0.8 hours, the temperature of the Aisha mill pulp is controlled at greater than 40 °C, and the proportion of the part with a particle size less than 0.074 mm in the fine-grained steel slag is controlled at greater than 90%.

2. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of crushing the reacted steel slag, the proportion of the part of the steel slag with a particle size less than 3 mm is controlled to be more than 75%.

3. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the air flow velocity at the lower end outlet of the conical barrel is controlled to be 55 m / s.

4. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the air flow velocity at the lower end outlet of the conical barrel is controlled to be 65 m / s.

5. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the air flow velocity at the lower end outlet of the conical barrel is controlled to be 75 m / s.

6. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the air flow velocity at the lower end outlet of the conical barrel is controlled to be 85 m / s.

7. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the air flow velocity at the lower end outlet of the conical barrel is controlled to be 95 m / s.

8. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the negative pressure inside the conical barrel is controlled to be 0.4 Mpa.

9. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the negative pressure inside the conical barrel is controlled to be 0.5 Mpa.

10. The method for reducing the content of highly active CaO in steel slag according to claim 1, characterized in that, during the process of negative pressure high-speed steam extraction and dehydration treatment, the negative pressure inside the conical barrel is controlled to be 0.6 Mpa.

11. The method for reducing the content of highly active CaO in steel slag according to any one of claims 1 to 10, characterized in that, The composition of the steel slag by weight percentage is: TFe = 1 - 7%, CaO = 42 - 57%, SiO 2 = 11 - 33%, MgO = 3 - 9%, Al 2 O 3 = 0.8 - 4.7%, Cr = 0.5 - 4.7%, Ni = 0.03 - 0.15%. The steel slag is a massive material with a particle size of 10 - 300 mm.

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