System and method for preparing green cementing material by thermal coupling of metallurgical slag

Abstract

The invention discloses a system for preparing a green cementing material by thermal coupling of metallurgical slag. Comprising a reaction furnace for receiving the hot blast furnace slag and the hot steel slag, and a stirring device for stirring the hot slag in the reaction furnace, the cooling and granulating system is used for receiving the hot-state slag from the reaction furnace and carrying out cooling and granulating treatment on the hot-state slag; and the grinding system is used for receiving slag particles from the cooling and granulating system and carrying out grinding on the slag particles. According to the system for preparing the green cementing material through metallurgical slag thermal-state coupling, after steel slag is subjected to thermal-state coupling modification, the cementing activity of steel slag micro powder is remarkably improved, especially the early activity is greatly improved, and the S95-level performance requirement of the slag micro powder is met; the content of f-CaO in the steel slag is greatly reduced, and the problem of volume stability of a steel slag product is solved. The invention further discloses a method for preparing the green cementing material through metallurgical slag thermal-state coupling.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and in particular, the present invention relates to a system and method for preparing green gelling materials by thermal coupling of metallurgical slag. Background Art

[0002] The resource utilization of steel slag is a difficult problem faced by steel enterprises. At present, hot steel slag is generally cooled and granulated by wet cooling processes such as hot stuffing method, drum method and wind crushing method. After granulation, the steel slag is crushed and magnetically separated to recover metal materials and returned to the converter and sintered for utilization. There are many ways to utilize the tailings after magnetic separation, which are mainly used in cement, roads, building materials and other fields, among which the application ratio in the cement industry exceeds 60%. Although steel slag contains a certain amount of hydraulic minerals such as C3S and C2S, the temperature of the steelmaking process exceeds 1600℃, which is much higher than the temperature of about 1300℃ in the cement production process. As a result, hydraulic minerals such as C3S and C2S have coarse crystals due to overburning, and the activity of hydration reaction is reduced, and the content is not high. The low gelling activity of steel slag, especially the low early activity, is one of the main problems restricting its application in cement. On the other hand, the high content of free CaO (f-CaO) in steel slag can easily cause volume stability problems of its products, which is also one of the factors restricting its application in cement. Due to the influence of the above reasons, in order to ensure the quality of cement, "General Portland Cement" (GB175-2023) will be implemented on June 1, 2024. This mandatory standard prohibits steel slag from being used as a mixing material for general Portland cement. This regulation will result in nearly 50 million tons of steel slag needing to find new ways to utilize it each year.

[0003] Chinese patent application number 202010178114.0 discloses a method for preparing a composite cementitious material by grinding using steel slag, slag and gypsum as raw materials. The specific method is: take steel slag particles, slag and gypsum, mix the above raw materials and grind them through a grinding device to obtain fine particles II, coarse particles II and coarse particles III. After hot air selection, the fine particles II enter the dust collector, and the coarse particles II fall back to the grinding disk of the grinding device for further grinding; the coarse particles III are removed by iron remover and then continue to be ground by the grinding device, so as to form a cycle until all the raw materials enter the dust collector, and the cementitious material is prepared. This method mixes steel slag, slag and gypsum in a cold state and prepares a mixed cementitious material by grinding. It is a physical change process. The specific surface area of ​​the cementitious material is mainly increased to 450m2 / kg-600m2 / kg by grinding, thereby improving the activity of the cementitious material. The problem is that increasing the specific surface area by grinding will increase the energy consumption of grinding. On the other hand, simply increasing the specific surface area has limited effect on improving the activity. At the same time, it does not solve the problem of the volume stability of steel slag.

[0004] The Chinese patent with application number 202211128811.0 discloses a steel slag early activity activator and its preparation method and application effect. The steel slag early activity activator is composed of the following raw materials in percentage by mass: 10-25% quicklime, 5-15% diethanol monoisopropanolamine, 30-45% metakaolin, and 20-50% water. The steel slag early activity activator is mixed with steel slag and stirred evenly to obtain active steel slag; the active steel slag and cement are mixed as a cementitious material to prepare active steel slag cement mortar or active steel slag cement concrete; the amount of the steel slag early activity activator is 0.2-0.3% of the mass of the steel slag; the amount of active steel slag in the cementitious material is 35-40%. The invention adopts the method of adding additives to improve the early activity of steel slag, without considering the problem that the overall activity of steel slag is lower than that of cement and slag powder, and also does not solve the problem of volume stability of steel slag.

[0005] The Chinese patent with application number 202311496700.X discloses a steel slag slag-based cementitious material and its preparation method and application. The materials described in the invention include the following components in parts by weight: 20-35 parts of steel slag powder, 40-55 parts of slag powder, 10-15 parts of fly ash, 10-15 parts of desulfurized gypsum, 0.5-1 parts of quicklime, 0-0.5 parts of sodium thiocyanate, and 0.1-0.5 parts of sodium silicate. The invention puts forward requirements for the chemical composition of each of the above-mentioned raw materials and the related properties of the moisture agent. On this basis, the cementitious material is obtained by mixing after pretreatment such as drying and crushing. The invention scheme is to prepare a cementitious material by physically mixing steel slag powder, slag powder and related materials in a cold state. It is a physical change process, which does not change the mineral composition of the steel slag powder itself, does not fundamentally change the cementitious activity of the steel slag powder itself, and fails to solve the problem of volume stability of steel slag.

[0006] The Chinese patent with application number 202311496700.X discloses a high-strength and high-toughness steel slag-based cementitious material and its preparation method. The steel slag-based cementitious material provided by the invention includes: 180-220 parts of slag, 180-220 parts of steel slag, 90-100 parts of cement, 1350-1400 parts of sand, rubber powder, polypropylene fiber, 4.5-5 parts of sodium hydroxide, 4.5-5 parts of desulfurized gypsum and 225-250 parts of water. After the raw materials are mixed, the mortar is mixed and formed, and then cured to obtain a high-strength and high-toughness steel slag-based cementitious material. This invention is to make a cementitious material by mixing steel slag with raw materials such as slag powder and cement. Similar to the aforementioned invention, it is a physical change process, which does not change the mineral composition of the steel slag powder itself, does not essentially change the cementitious activity of the steel slag powder itself, and fails to solve the problem of volume stability of steel slag.

[0007] The Chinese patent application number 202111458679.5 discloses a steel slag cementitious material and its preparation method and application. The invention crushes the steel slag raw material into 0.05-4.0 mm and then places it in a grinding device, adds liquid additives and crystal form control agents and mixes them evenly, and grinds the mixed steel slag to a specific surface area of ​​not less than 200m 2 / kg, wet flue gas containing carbon dioxide is introduced and continued to grind for 1-60min to obtain steel slag cementitious material. The invention improves the hydration activity and stability of steel slag by adding liquid additives, crystal form controller and wet flue gas containing carbon dioxide. 2 The reaction with steel slag is greatly affected by kinetic conditions and the reaction effect is difficult to guarantee.

[0008] In the prior art, the cementitious material is prepared by mixing steel slag with slag powder, gypsum and other raw materials, or adding additives and passing CO 2 Gas and other methods are used to increase the activity of cementitious materials and improve their stability, mainly by changing their external form through physical changes.

[0009] It is hoped to provide a system and method for preparing green cementitious materials by thermal coupling of metallurgical slag, particularly regarding how to change the mineral composition of metallurgical slag by thermal coupling of metallurgical slag, increase the content of its cementitious active mineral components, and reduce the f-CaO content. Summary of the invention

[0010] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a system for preparing green cementitious materials by hot coupling of metallurgical slag, the purpose of which is to increase the content of cementitious active mineral components in the green cementitious materials and reduce the f-CaO content.

[0011] The present invention aims to solve the problem of low gelling activity of steel slag, especially low early activity and high f-CaO content leading to volume expansion of products. By adopting the coupling reaction of steel slag and blast furnace slag in hot state and a reasonable cooling system, the mineral phase reconstruction in the metallurgical slag is achieved. The magnesia aluminum feldspar (Ca2+) in the hot blast furnace slag is reduced. 4 Al 2 Mg 2 Si 3 O 14 ) and magnesia calcite (Ca 3 MgSi 2 O 8 ) and calcium ferrite Ca in steel slag 2 Fe 2 O 5It reacts with CaO to generate active minerals such as C3S, C2S, C3A, C4AF, and reduces the f-CaO content. The activity of the metallurgical slag powder after grinding reaches or even exceeds that of slag powder. It is a green cementitious material with good cementitious activity and volume stability.

[0012] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a system for preparing green cementitious materials by hot coupling of metallurgical slag, including a reactor for receiving hot blast furnace slag and hot steel slag, a stirring device for stirring the hot slag in the reactor, a cooling granulation system for receiving the hot slag from the reactor and cooling and granulating the hot slag, and a grinding system for receiving slag particles from the cooling granulation system and grinding the slag particles.

[0013] The present invention also provides a method for preparing green gelling material by hot coupling of metallurgical slag, which adopts the system and comprises the steps of:

[0014] S1, adding the hot blast furnace slag and the hot steel slag into the reaction furnace;

[0015] S2, starting the stirring device to stir the hot slag in the reaction furnace;

[0016] S3, standing reaction;

[0017] S4, adding the hot molten slag in the reaction furnace into the cooling and granulation system, and obtaining slag particles after cooling and granulation treatment;

[0018] S4, adding the slag particles into the grinding system, grinding the slag particles to obtain a green cementitious material product.

[0019] In the step S1, before the hot blast furnace slag is poured into the reaction furnace, the temperature of the hot blast furnace slag should be ≥1350°C.

[0020] In the step S1, before the hot slag is poured into the reaction furnace, the temperature of the hot slag should be ≥1400°C.

[0021] In the step S1, the mass proportion of the hot blast furnace slag poured into the reaction furnace is 10-40%, and the mass proportion of the hot steel slag is 60-90%.

[0022] In the step S2, when the stirring device is started to stir the hot slag in the reaction furnace, the bottom of the stirring head of the stirring device stirs for 30-60 seconds at a first distance and a second distance from the liquid surface of the reaction furnace, respectively.

[0023] In the step S3, after the stirring device finishes stirring, the duration of the static reaction is 10-15 seconds.

[0024] In the step S4, before the hot molten slag is poured into the cooling and granulating system, the temperature of the hot molten slag should be ≥1250°C.

[0025] In step S4, the cooling and granulation method is wind crushing granulation cooling, water quenching granulation cooling or a combination of the two, and the cooling rate is ≥10°C / S.

[0026] In the step S5, the slag particles are dried and subjected to magnetic separation treatment, so that the moisture content of the slag particles is ≤2% and the metallic iron content is ≤2% before being added to the grinding system.

[0027] The system for preparing green gelling materials by hot coupling of metallurgical slag of the present invention has the following beneficial effects:

[0028] 1. After the steel slag is thermally coupled modified, the gelling activity of the steel slag powder is significantly improved, especially the early activity is greatly improved, reaching the performance requirements of slag powder S95;

[0029] 2. The f-CaO content in steel slag is greatly reduced, solving the problem of volume stability of steel slag products;

[0030] 3. The solution to the above two problems lays a foundation for the use of steel slag as cementitious material and provides a new solution to the problem of steel slag utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] This specification includes the following drawings, which show the following contents:

[0032] Figure 1 It is a schematic diagram of the structure of the system for preparing green gelling materials by hot coupling of metallurgical slag according to the present invention;

[0033] The markings in the figure are:

[0034] 1. The first slag pot; 2. The second slag pot; 3. The reaction furnace; 4. The stirring device; 5. The cooling and granulation system; 6. The grinding system. DETAILED DESCRIPTION

[0035] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and facilitating their implementation.

[0036] It should be noted that, in the following embodiments, the “first” and “second” mentioned do not represent an absolute distinction in structure and / or function, nor do they represent a sequential order of execution, but are merely for the convenience of description.

[0037] The present invention aims at the problem of low cementitious activity of steel slag, especially low early activity and high f-CaO content leading to volume expansion of products. By adopting the coupling reaction of steel slag and blast furnace slag in a hot state and a reasonable cooling system, the mineral phase reconstruction in the metallurgical slag is achieved, and active minerals such as C3S and C2S are generated in large quantities and precipitated preferentially. The activity of the metallurgical slag micropowder after grinding reaches or even exceeds the activity of the slag micropowder, and the f-CaO content is greatly reduced. The present invention is a green cementitious material with good cementitious activity and volume stability.

[0038] Magnesium aluminum feldspar (Ca) in hot blast furnace slag during the thermal coupling process of metallurgical slag 4 Al 2 Mg 2 Si 3 O 14 ) and calcium ferrite Ca in steel slag 2 Fe 2 O 5 Reaction occurs to form tricalcium aluminate (3CaO·Al 2 O 3 , referred to as C3A), tricalcium silicate (3CaO·SiO 2 , referred to as C3S), tetracalcium aluminoferrite (4CaO·Al 2 O 3 ·Fe 2 O 3 , referred to as C4AF) and olivine (Mg 4 Si 4 O 12 ), converting minerals without gelling activity such as magnesia aluminum feldspar and calcium ferrite into minerals with high gelling activity such as C3A, C3S, and C4AF, thereby increasing the content of minerals with gelling activity in metallurgical slag and improving the gelling activity of metallurgical slag. 3 MgSi 2 O 8 ) reacts with excess lime (CaO) in steel slag to form C3S, CaMgSiO 4 , increasing the C3S active mineral content while reducing the f-CaO content. The specific reaction formulas are as follows (1) and (2):

[0039] 2Ca 4 Al 2 Mg 2 Si 3 O 14 +Ca 2 Fe 2 O 5 =3CaO·Al 2 O 3 +3CaO·SiO 2 +4CaO·Al2 O 3 ·Fe 2 O 3 +Mg 4 Si 4 O 12 (1)

[0040] Ca 3 MgSi 2 O 8 +CaO=3CaO·SiO 2 +CaMgSiO 4 (2)

[0041] Based on the above theoretical analysis and experimental conclusions, the present invention proposes a system and method for preparing green cementitious materials by thermal coupling of metallurgical slag. The mineral composition of the metallurgical slag is changed by thermal coupling of the metallurgical slag, the content of its cementitious active mineral components is increased, and a green cementitious material with good cementitious activity and volume stability is prepared.

[0042] The present invention aims to solve the problem of low gelling activity of steel slag, especially low early activity and high f-CaO content leading to volume expansion of products. By adopting the coupling reaction of steel slag and blast furnace slag in hot state and a reasonable cooling system, the mineral phase reconstruction in the metallurgical slag is achieved. The magnesia aluminum feldspar (Ca2+) in the hot blast furnace slag is reduced. 4 Al 2 Mg 2 Si 3 O 14 ) and magnesia calcite (Ca 3 MgSi 2 O 8 ) and calcium ferrite Ca in steel slag 2 Fe 2 O 5 It reacts with CaO to generate active minerals such as C3S, C2S, C3A, C4AF, and reduces the f-CaO content. The activity of the metallurgical slag powder after grinding reaches or even exceeds that of slag powder. It is a green cementitious material with good cementitious activity and volume stability.

[0043] like Figure 1 As shown, the present invention provides a system for preparing green cementitious materials by hot coupling of metallurgical slag, including a reactor for receiving hot blast furnace slag and hot steel slag, a stirring device for stirring the hot molten slag in the reactor, a cooling granulation system for receiving the hot molten slag from the reactor and cooling and granulating the hot molten slag, and a grinding system for receiving slag particles from the cooling granulation system and grinding the slag particles.

[0044] Specifically, if Figure 1As shown, the hot blast furnace slag contained in the first slag pot is poured into the reaction furnace, and the hot steel slag contained in the second slag pot is poured into the reaction furnace.

[0045] The present invention also provides a method for preparing green gelling material by hot coupling of metallurgical slag, which adopts the above system and comprises the following steps:

[0046] S1, adding hot blast furnace slag and hot steel slag into a reaction furnace;

[0047] S2, starting the stirring device to stir the hot slag in the reaction furnace;

[0048] S3, standing reaction;

[0049] S4, adding the hot molten slag in the reaction furnace into a cooling and granulating system, and obtaining slag particles after cooling and granulating;

[0050] S4. Add the slag particles into the grinding system, grind the slag particles to obtain green cementitious material products.

[0051] In the above step S1, the hot blast furnace slag in the first slag pot is first poured into the reaction furnace, and then the hot steel slag in the second slag pot is poured into the reaction furnace. After the hot blast furnace slag and the hot steel slag are poured into the reaction furnace, they are mixed to form hot molten slag.

[0052] In the above step S1, the hot blast furnace slag is poured into the reaction furnace through the first slag pot. Before the hot blast furnace slag is poured into the reaction furnace, the temperature of the hot blast furnace slag should be ≥1350° C. On the one hand, the fluidity of the blast furnace slag is ensured to facilitate pouring, and good kinetic conditions are provided for the subsequent liquid phase reaction.

[0053] In the above step S1, the hot slag is poured into the reactor through the second slag pot. Before the hot slag is poured into the reactor, the temperature of the hot slag should be ≥1400° C. This ensures the fluidity of the slag for easy pouring and provides good kinetic conditions for subsequent liquid phase reactions.

[0054] In the above step S1, the mass proportion of hot blast furnace slag poured into the reaction furnace is 10-40%, and the mass proportion of hot steel slag is 60-90%. By controlling the ratio of blast furnace slag to steel slag, the advantageous precipitation of gelled active minerals in the liquid phase reaction process can be better controlled.

[0055] like Figure 1 As shown, the stirring device is inserted into the reaction furnace. In the above step S2, when the stirring device is started to stir the hot slag in the reaction furnace, the bottom of the stirring head of the stirring device stirs for 30-60s at a first distance and a second distance from the liquid surface of the reaction furnace. The stirring head of the stirring device is located below the liquid surface in the reaction furnace, and the first distance is smaller than the second distance.

[0056] In the above step S2, when the distance between the bottom of the stirring head of the stirring device and the liquid surface of the reactor is the first distance, the stirring device stirs the hot slag in the reactor for a duration of 30-60s; then the stirring head of the stirring device is controlled to descend so that the distance between the bottom of the stirring head of the stirring device and the liquid surface of the reactor reaches the second distance, and then the stirring device continues to stir. The stirring device stirs the hot slag in the reactor for a duration of 30-60s, which can enhance the stirring effect and make the slag liquid phase reaction more complete.

[0057] Preferably, the first distance is 50 cm and the second distance is 100 cm.

[0058] In the above step S3, after the stirring device finishes stirring, the hot slag is stirred evenly, and then allowed to stand for a certain period of time, the duration of the standing reaction is 10-15 seconds, so that the liquid phase reaction can reach an equilibrium state as much as possible. Exemplarily, the duration of the standing reaction can be 11 seconds, 12 seconds, 13 seconds, 14 seconds, or 15 seconds.

[0059] In the above step S4, before the hot molten slag is poured into the cooling and granulating system, the temperature of the hot molten slag should be ≥1250° C. This can ensure that the molten slag after hot coupling maintains good fluidity during the cooling and granulating process.

[0060] In the above step S4, the cooling granulation method is wind crushing granulation cooling, water quenching granulation cooling, a combination of wind crushing granulation cooling and water quenching granulation cooling, or other cooling granulation methods, and the cooling rate is ≥10°C / S. Ensuring a certain cooling rate is conducive to the formation of gelled active minerals and glass phase.

[0061] In the above step S5, the slag particles are dried and magnetically separated so that the moisture content of the slag particles is ≤2% and the metallic iron content is ≤2% before being added to the grinding system. Controlling the moisture content is conducive to the efficient operation of the grinding system, and controlling the metallic iron content is conducive to the stable operation of the grinding system equipment and the improvement of the gelling activity of the product.

[0062] In the above step S5, the slag particles are ground by the grinding system, and then collected by air separation after grinding, with a specific surface area of ​​≥360m 2 / kg of micro powder is used as a cementitious material, with a 7d activity index ≥70, a 28d activity index ≥95, and f-CaO ≤0.5%.

[0063] The system and method for preparing green gelling materials by hot coupling of metallurgical slag of the present invention have the following advantages:

[0064] 1. Through experimental and theoretical analysis, the reaction mechanism of the metallurgical slag thermal coupling process was clarified. Through reasonable proportion regulation, the formation of highly active mineral components such as C3S, C2S, C3A, and C4AF in the coupled slag was promoted. This provided a theoretical basis for improving the activity of metallurgical slag and solving the problem of low early strength of steel slag.

[0065] 2. In the process of hot coupled reaction of metallurgical slag, the magnesium silicate (Ca 3 MgSi 2 O 8 ) reacts with CaO in steel slag to generate C3S to improve activity, while reducing the content of f-CaO in the slag, providing a theoretical basis for solving the problem of steel slag volume stability;

[0066] 3. By mixing blast furnace slag and steel slag in a hot state, completing the high-temperature coupling reaction through gas stirring in the reactor, the mineral composition of metallurgical slag can be regulated, and by reasonable cooling rate control, the advantageous precipitation of high-cementitious active minerals can be promoted. The cooled and granulated metallurgical slag can be ground into a high-activity green cementitious material.

[0067] Embodiment 1:

[0068] In this embodiment, hot blast furnace slag and hot steel slag are poured into the reaction furnace respectively, the hot blast furnace slag accounts for 15%, and the furnace temperature is 1405°C; the hot steel slag accounts for 85%, and the furnace temperature is 1426°C; the stirring device is started, and the stirring head is stirred for 32s and 45s at 50cm and 100cm from the liquid surface respectively, and the static reaction time after stirring is 15s; the slag temperature is 1340°C, and the wind crushing cooling granulation system is introduced, and the cooling rate is 12°C / S. After cooling and granulation, the slag particles are dried and magnetically separated. The moisture content of the slag particles before entering the mill is 1.6%, and the metallic iron content is 1.2%; the slag particles are collected by grinding and air separation, and the specific surface area is 381m 2 / kg of cementitious material, its 7d activity index was 71, 28d activity index was 96, and f-CaO content was 0.48%.

[0069] Embodiment 2:

[0070] In this embodiment, hot blast furnace slag and hot steel slag are poured into the reaction furnace respectively, with the hot blast furnace slag accounting for 20% and the furnace temperature being 1395°C; the hot steel slag accounting for 80% and the furnace temperature being 1405°C; the stirring device is started, and the stirring is performed for 35s and 50s at 50cm and 100cm from the top of the stirring head to the liquid surface respectively, and the stirring is stopped for 15s; the slag temperature is 1316°C, and the wind crushing cooling granulation system is introduced, and the cooling rate is 15°C / S. After cooling and granulation, the slag particles are dried and magnetically separated. The moisture content of the slag particles before entering the mill is 1.4%, and the metallic iron content is 1.1%; the slag particles are collected by pulverizing and air separation, and the specific surface area is 394m2 / kg of cementitious material, its 7d activity index was 73, 28d activity index was 98, and f-CaO content was 0.32%.

[0071] Embodiment 3:

[0072] In this embodiment, hot blast furnace slag and hot steel slag are poured into the reaction furnace respectively, the hot blast furnace slag accounts for 30%, and the temperature of the furnace is 1403°C; the hot steel slag accounts for 70%, and the temperature of the furnace is 1413°C; the stirring device is started, and the stirring head is stirred for 30s and 40s at 50cm and 100cm from the liquid surface respectively, and the stirring is stopped for 12s; the slag temperature is 1328°C, and the water quenching cooling granulation system is introduced, and the cooling rate is 30°C / S. After cooling and granulation, the slag particles are dried and magnetically separated. The moisture content of the slag particles before entering the mill is 1.5%, and the metallic iron content is 0.9%; the slag particles are collected by pulverization and air separation, and the cementitious material with a specific surface area of ​​382m2 / kg is tested to have a 7d activity index of 75, a 28d activity index of 100, and an f-CaO content of 0.15%.

[0073] Embodiment 4:

[0074] In this embodiment, hot blast furnace slag and hot steel slag are poured into the reaction furnace respectively, with the hot blast furnace slag accounting for 40% and the furnace temperature being 1394°C; the hot steel slag accounting for 60% and the furnace temperature being 1423°C; the stirring device is started, and the stirring is performed for 35s and 50s at 50cm and 100cm from the top of the stirring head to the liquid surface, respectively. After the stirring is completed, the reaction is allowed to stand for 12s; the slag temperature is 1331°C, and the water quenching cooling granulation system is introduced, with a cooling rate of 28°C / S. After cooling and granulation, the slag particles are dried and magnetically separated, and the moisture content of the slag particles before entering the mill is 1.6%, and the metallic iron content is 0.8%; the slag particles are collected by pulverizing and air separation, with a specific surface area of ​​389m 2 / kg of cementitious material, its 7d activity index was 78, 28d activity index was 101, and f-CaO content was 0.08%.

[0075] Embodiment 5:

[0076] In this embodiment, hot blast furnace slag and hot steel slag are poured into the reaction furnace respectively, with the hot blast furnace slag accounting for 25% and the furnace temperature being 1387°C; the hot steel slag accounting for 75% and the furnace temperature being 1403°C; the stirring device is started, and the stirring is performed for 30s and 48s at 50cm and 100cm from the top of the stirring head to the liquid surface respectively, and the stirring is stopped for 15s; the slag temperature is 1311°C, and the wind crushing granulation and atomization cooling system is introduced, with a cooling rate of 20°C / S. After cooling and granulation, the slag particles are dried and magnetically separated, and the moisture content of the slag particles before entering the mill is 1.8%, and the metallic iron content is 1.1%; the slag particles are collected by grinding and air separation, with a specific surface area of ​​397m 2 / kg of cementitious material, its 7d activity index was 75, 28d activity index was 99, and f-CaO content was 0.19%.

[0077] Comparative Example 1:

[0078] The hot slag is directly treated by the hot stuffing process, and then processed by the rod mill magnetic separation. The tailings have a metallic iron content of 2.4%. After drying to a moisture content of 2.3%, it enters the mill and is ground to a specific surface area of ​​401m 2 / kg, its 7d activity index was 55, 28d activity index was 69, and f-CaO content was 2.6%.

[0079] Comparative Example 2:

[0080] The hot slag is directly treated by the drum process, and then processed by rod mill magnetic separation. The tailings have a metallic iron content of 2.0%. After drying to a moisture content of 2.1%, it enters the mill and is ground to a specific surface area of ​​415m 2 / kg, its 7d activity index was 59, 28d activity index was 73, and f-CaO content was 3.1%.

[0081] Comparative Example 3:

[0082] The hot slag is directly treated by wind crushing process and magnetic separation. The tailings have a metal iron content of 0.2%. After drying to a moisture content of 1.6%, it enters the mill and is ground to a specific surface area of ​​410m 2 / kg, its 7d activity index was 60, 28d activity index was 75, and f-CaO content was 1.0%.

[0083] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A system for preparing green cementitious materials by hot coupling of metallurgical slag, characterized in that: The invention comprises a reaction furnace for receiving hot blast furnace slag and hot steel slag, a stirring device for stirring the hot molten slag in the reaction furnace, a cooling granulation system for receiving the hot molten slag from the reaction furnace and cooling and granulating the hot molten slag, and a grinding system for receiving slag particles from the cooling granulation system and grinding the slag particles.

2. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to claim 1, characterized in that: The system of claim 1 is used, and includes the steps of: S1, adding the hot blast furnace slag and the hot steel slag into the reaction furnace; S2, starting the stirring device to stir the hot slag in the reaction furnace; S3, standing reaction; S4, adding the hot molten slag in the reaction furnace into the cooling and granulation system, and obtaining slag particles after cooling and granulation treatment; S4, adding the slag particles into the grinding system, grinding the slag particles to obtain a green cementitious material product.

3. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to claim 2, characterized in that: In the step S1, before the hot blast furnace slag is poured into the reaction furnace, the temperature of the hot blast furnace slag should be ≥1350°C.

4. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to claim 2, characterized in that: In the step S1, before the hot slag is poured into the reaction furnace, the temperature of the hot slag should be ≥1400°C.

5. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 4, characterized in that: In the step S1, the mass proportion of the hot blast furnace slag poured into the reaction furnace is 10-40%, and the mass proportion of the hot steel slag is 60-90%.

6. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 5, characterized in that: In the step S2, when the stirring device is started to stir the hot slag in the reaction furnace, the bottom of the stirring head of the stirring device stirs for 30-60 seconds at a first distance and a second distance from the liquid surface of the reaction furnace, respectively.

7. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 5, characterized in that: In the step S3, after the stirring device finishes stirring, the duration of the static reaction is 10-15 seconds.

8. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 5, characterized in that: In the step S4, before the hot molten slag is poured into the cooling and granulating system, the temperature of the hot molten slag should be ≥1250°C.

9. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 5, characterized in that: In step S4, the cooling and granulation method is wind crushing granulation cooling, water quenching granulation cooling or a combination of the two, and the cooling rate is ≥10°C / S.

10. The method for preparing green cementitious materials by hot coupling of metallurgical slag according to any one of claims 2 to 5, characterized in that: In the step S5, the slag particles are dried and subjected to magnetic separation treatment, so that the moisture content of the slag particles is ≤2% and the metallic iron content is ≤2% before being added to the grinding system.

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