A method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag

Abstract

The application discloses a method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag. The molten titanium-containing blast furnace slag is directly discharged into a slag pit, and single cooling or mixed cooling is controlled for crystallization treatment by using the latent heat of the molten titanium-containing blast furnace slag, so that the internal sulfur-containing gas and / or water vapor of the molten slag is diffused and escaped, and a blank body with a connected porous structure is obtained. The blank body after cooling is cut and polished to obtain the porous microcrystalline stone, and the utilization rate of the titanium-containing blast furnace slag and the added value of the porous microcrystalline stone product are improved.

Description

TECHNICAL FIELD

[0001] The application relates to a method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag, and belongs to the technical field of resource comprehensive utilization. BACKGROUND

[0002] With the rapid development of economy, industrial production not only brings great economic benefits, but also produces a large amount of industrial waste. Industrial waste slag is difficult to handle due to its large output, many types, difficult flow, large composition fluctuation and other characteristics. Titanium-containing blast furnace slag is a solid waste produced in the process of smelting vanadium-titanium ore. Due to the high TiO2 content in the slag, the hydration reaction activity is significantly deteriorated and cannot be directly used for cement. The technology for recovering and utilizing titanium from the slag is not mature. Currently, Ti can only be extracted from medium and high titanium slag. However, the process generally has problems such as high energy consumption, low extraction rate and serious environmental pollution. Therefore, the titanium-containing slag is currently directly landfilled, which not only occupies a large amount of land resources and pollutes the environment, but also wastes valuable resources in the slag.

[0003] Titanium-containing blast furnace slag belongs to CaO-MgO-Al2O3-SiO2 system blast furnace slag, and its composition meets the manufacturing requirements of porous microcrystalline stone. Porous microcrystalline stone has been widely used in metallurgical, power, building material and other industrial departments, and is a new type of material with wide application. In addition, the structural strength of porous microcrystalline stone is better than that of natural stone, which can replace the use of natural stone and protect the environment.

[0004] Patent No. CN112340988A discloses a method for preparing microcrystalline glass based on TiO2 in titanium-containing blast furnace slag as a nucleating agent. However, the production process needs to remelt and cool the cold titanium-containing blast furnace slag again, and then sinter, which is complex. In the process of remelting and cooling the cold titanium-containing blast furnace slag again, the heat energy utilization rate of the molten slag is low, and energy is wasted. Patent No. CN119241078A discloses a microcrystalline cast stone and a preparation method and application thereof. The microcrystalline cast stone is prepared by mixing various waste materials with titanium-containing blast furnace slag. The mixing of other solid wastes reduces the application proportion of titanium-containing blast furnace slag. The composition of the sample is complex, and the cold titanium-containing blast furnace slag is used, which cannot utilize the heat of molten titanium-containing blast furnace slag, and the energy utilization rate of the molten slag is low. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag. The cooling rate of the titanium-containing blast furnace slag is controlled to obtain a porous microcrystalline stone product, which improves the utilization rate of the titanium-containing blast furnace slag and the added value of the product.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] In a first aspect, the present application provides a method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag, the method comprising:

[0008] The molten titanium-containing blast furnace slag is directly discharged into a slag pit, and the latent heat of the molten titanium-containing blast furnace slag is utilized to control the cooling conditions for crystallization treatment, so as to promote the diffusion and escape of sulfur-containing gas and / or water vapor in the molten slag, and obtain a green body with a connected porous structure; the cooling conditions include single cooling or mixed cooling.

[0009] After the green body is cooled, cutting and polishing are performed to obtain the porous microcrystalline stone.

[0010] In combination with the first aspect, further, the chemical composition of the molten titanium-containing blast furnace slag includes, in terms of mass percentage:

[0011] CaO: 24%-32%, MgO: 5%-15%, SiO2: 20%-32%, Al2O3: 8%-16%, TiO2: 10%-25%, Fe2O3: 0-10%, SO2: 1%-2%, and other components: 0-3%; the other components include any two or more of K2O, Na2O, V2O5, and MnO.

[0012] Further, the cooling mode of the single cooling is any one of natural cooling, air blast cooling, and water spray cooling; the cooling mode of the mixed cooling is a combination of at least two of natural cooling, air blast cooling, and water spray cooling.

[0013] Further, the mixed cooling includes the following stages:

[0014] First stage: from the initial temperature of the molten titanium-containing blast furnace slag to 1100℃, slow cooling is performed at a cooling rate of 1-5 o C / min;

[0015] Second stage: from 1100℃ to 600℃, rapid cooling is performed at a cooling rate of 10-30 o C / min;

[0016] Third stage: from 600℃, slow cooling is performed at a cooling rate of 5-10 o C / min.

[0017] Further, the initial temperature of the molten titanium-containing blast furnace slag is 1450-1550℃.

[0018] Further, the sulfur-containing gas includes SO2 and / or H2S.

[0019] In a second aspect, the present application provides a porous microcrystalline stone prepared according to any of the methods of the first aspect.

[0020] In combination with the second aspect, further, the porosity of the porous microcrystalline stone is 2%-10%, and the compressive strength is 70-100 MPa.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] The application provides a method for preparing a porous microcrystalline stone from molten titanium-containing blast furnace slag, which completely utilizes solid waste, i.e., titanium-containing blast furnace slag, and does not need to add nucleating agents or conditioning agents, thereby achieving effective utilization of waste resources.

[0023] The molten titanium-containing blast furnace slag is directly utilized, without external heating, thereby reducing energy waste caused by reheating of the cooled slag and reducing production cost.

[0024] The application forms a porous structure by controlling gas diffusion during the cooling process, optimizes the pore structure and mechanical properties of the microcrystalline stone, and improves the compressive strength and acid and alkali resistance. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A method for preparing a porous microcrystalline stone from molten titanium-containing blast furnace slag is provided in the application;

[0026] Figure 2 A macrograph and an XRD graph of the porous microcrystalline stone obtained in Example 1 of the application are provided;

[0027] Figure 3 A surface morphology graph and an XRD graph of the porous microcrystalline stone obtained in Example 2 of the application are provided;

[0028] Figure 4 A surface morphology graph of the porous microcrystalline stone obtained in Example 3 of the application is provided;

[0029] Figure 5 A cross-sectional graph and an XRD graph of the porous microcrystalline stone obtained in Comparative Example 1 of the application are provided;

[0030] Figure 6 A cross-sectional graph and an XRD graph of the porous microcrystalline stone obtained in Comparative Example 2 of the application are provided. DETAILED DESCRIPTION

[0031] The technical solution of the application will be described in detail below with reference to the drawings and specific examples, and it should be understood that the specific features in the examples and the examples are detailed descriptions of the technical solution of the application, rather than limitations of the technical solution of the application.

[0032] The application provides a method for preparing a porous microcrystalline stone from molten titanium-containing blast furnace slag, and a flowchart is as shown in Figure 1 The method comprises the following steps:

[0033] (1) The molten titanium-containing blast furnace slag is discharged from a blast furnace to a slag pit;

[0034] (2) 1450 o C-1550 o The molten titanium-containing blast furnace slag of C is cooled by any one of natural cooling, air cooling, water spraying cooling, or a combination of multiple cooling methods to control the diffusion of gas and form pore channels, so as to obtain a green body with a connected porous structure.

[0035] The cooling rate of the single cooling method is less than 2 o C / min; and the cooling rate of the multiple cooling method includes the following three stages:

[0036] The first stage: slow cooling from the initial temperature of the molten titanium-containing blast furnace slag to 1100℃, and the cooling rate is 1-5 o C / min;

[0037] The second stage: slow cooling from 1100 o C to 600 o C, and the cooling rate is 10-30 o C / min;

[0038] The third stage: slow cooling below 600 o C, and the cooling rate is 5-10 o C / min.

[0039] (3) After the green body is completely cooled, it is cut and polished to obtain a porous microcrystalline stone.

[0040] In the embodiments of the present application, the chemical composition of the molten titanium-containing blast furnace slag includes, by mass percentage: CaO: 24%-32%, MgO: 5%-15%, SiO2: 20%-32%, Al2O3: 8%-16%, TiO2: 10%-25%, Fe2O3: 0-10%, SO2: 1%-2%, and other components: 0-3%.

[0041] The other components include any two or more of K2O, Na2O, V2O5, and MnO.

[0042] The temperature of the molten titanium-containing blast furnace slag is higher than 1450 o C, specifically 1450-1550 o C.

[0043] In some embodiments of the present application, the cooling method can be natural cooling or air cooling to below 200 o C.

[0044] In specific embodiments of the present application, unless otherwise specified, the experimental environment and parameter conditions of each group in the test are consistent, except for the differences explicitly indicated.

[0045] The application further provides a method for preparing porous microcrystalline stone from molten titanium-containing blast furnace slag.

[0046] Example 1

[0047] The components of the molten titanium-containing blast furnace slag in this example are as follows in terms of percentage by mass: CaO: 29.94%; MgO: 9.67%; SiO2: 24.31%; Al2O3: 13.12%; TiO2: 17.26%; Fe2O3: 1.72%; SO2: 1.85%; K2O: 0.53%; Na2O: 0.98%; and MnO: 0.52%. The steps for preparing the porous microcrystalline stone from the molten titanium-containing blast furnace slag are as follows:

[0048] The molten titanium-containing blast furnace slag is directly discharged into a slag pit, and the molten titanium-containing blast furnace slag is water-cooled to 200 o C in the slag pit to obtain a green body with a connected porous structure; wherein the cooling rate during the water-cooling process is controlled to be 1 o C / min slow cooling;

[0049] After the green body is completely cooled, cutting and polishing are performed to obtain the porous microcrystalline stone sample.

[0050] The microcrystalline stone sample prepared in this example is as shown in Figure 2 , Figure 2 Figure (a) is a macrograph of the porous microcrystalline stone, and the surface presents a sparse porous condition. The sample density is 2.9 g / cm 3 , and the porosity is 2%, Figure 2 Figure (b) is an XRD graph of the porous microcrystalline stone. The main crystal phases are diopside and perovskite. The compressive strength of the sample is 100 MPa, and the acid and alkali resistance is 99.3%.

[0051] Example 2

[0052] The components of the molten titanium-containing blast furnace slag in this example are as follows in terms of percentage by mass: CaO: 27.78%; MgO: 7.85%; SiO2: 26.08%; Al2O3: 12.10%; TiO2: 19.68%; Fe2O3: 4.57%; SO2: 1%; K2O: 0.07%; and Na2O: 0.08%.

[0053] The steps for preparing the porous microcrystalline stone from the molten titanium-containing blast furnace slag are as follows:

[0054] (1) The molten titanium-containing blast furnace slag is directly discharged into a slag pit, and the molten titanium-containing blast furnace slag is naturally cooled to 1100 o C in the slag pit, and then the molten slag is rapidly cooled by air blowing and water spraying, and cooled to 600o After the temperature drops below 200°C, spray water to cool it down. o Below C.

[0055] (2) During the cooling process from 1550 o C-1100 o The cooling rate of C is 1 o C / min, 1100 o C-600 o The cooling rate of C is 30. o C / min, 600 o C has a cooling rate of 10 o C / min.

[0056] (3) After complete cooling, the microcrystalline stone sample is cut and polished. Sample images are shown below. Figure 3 As shown, Figure 3 Image (a) shows the surface morphology of the sample, which exhibits a sparse and porous structure with a density of 2.82 g / cm³. 3 The porosity is 5%. Figure 3 (b) is the XRD pattern of the sample. The main crystalline phases are pyroxene and perovskite. The compressive strength of the sample is 89 MPa and the acid and alkali resistance is 99.1%.

[0057] Example 3:

[0058] In this embodiment, the composition of the molten titanium-containing blast furnace slag is as follows (by mass percentage):

[0059] CaO: 29.78%; MgO: 7.85%; SiO2: 25.08%; Al2O3: 12.10%; TiO2: 18.68%; Fe2O3: 4.37%; SO2: 1%; K2O: 0.17%; Na2O: 0.18%.

[0060] The steps for preparing porous microcrystalline stone based on molten titanium-containing blast furnace slag in this embodiment are as follows:

[0061] Molten titanium-containing blast furnace slag is directly discharged into the slag pit, where it is naturally cooled to 1100°C. o C. Subsequently, forced air cooling and water spraying were used to rapidly cool the molten slag to 600°C. o After the temperature drops below 200°C, spray water to cool it down. o Below C, a blank with a connected porous structure is obtained.

[0062] During the cooling process, from 1550 o C-1100 o The cooling rate of C is 5 o C / min, 1100 o C-600 oC cooling rate is 10 o C / min, 600 o C cooling rate is 5 o C / min.

[0063] After the green body is completely cooled, the microcrystalline stone sample is cut and polished to obtain a porous microcrystalline stone sample. The apparent morphology of the microcrystalline stone sample prepared in this embodiment is shown in Figure 4 , the surface presents a sparse and porous condition, the sample density is 2.63 g / cm 3 , the porosity is 10%, the compressive strength of the sample is 70 MPa, and the acid and alkali resistance is 98.4%.

[0064] Comparative Example 1:

[0065] The raw materials of Comparative Example 1 mainly include titanium-containing blast furnace slag and a conditioning agent, the titanium-containing blast furnace slag accounts for 98% of the total mass percentage, and the conditioning agent accounts for 2% of the total mass percentage. The conditioning agent is a mixture of quartz sand and calcium fluoride.

[0066] Among them, the composition of the titanium-containing blast furnace slag is as follows in terms of mass percentage: CaO: 27.78%; MgO: 7.85%; SiO2: 26.08%; Al2O3: 12.10%; TiO2: 19.68%; Fe2O3: 4.57%; SO2: 1%; K2O: 0.07%; Na2O: 0.08%.

[0067] The process of preparing the porous microcrystalline stone in this comparative example is as follows:

[0068] The molten titanium-containing blast furnace slag and the conditioning agent are homogenized at 1500 o C for 50 min in a conditioning furnace for casting, and then cooled by setting the cooling mode to obtain a microcrystalline stone sample.

[0069] The cooling mode is selected from any one of natural cooling, air blast cooling, and furnace cooling to cool to below 200 o C; the cooling rate is set to 1 o C / min for cooling.

[0070] The microcrystalline stone sample cooled to below 200 o C is cut, and the sample picture is shown in Figure 5 , Figure 5 , (a) is a sample cross-sectional view, the cross section presents that part of the holes is large, part of the holes is small, part of the structure is dense, and the pore distribution is uneven, and the sample density is 2.87 g / cm 3 ; Figure 5 (b) is a sample XRD graph, the main crystal phases are perovskite and diopside, and a small part of spinel, the sample porosity is less than 1%, which is inconsistent with the expected target of product design.

[0071] Compare with Example 2:

[0072] The raw materials of Comparative Example 2 mainly include titanium-containing blast furnace slag and conditioning agent. The titanium-containing blast furnace slag accounts for 95% of the total mass percentage, and the conditioning agent accounts for 5% of the total mass percentage. The conditioning agent is mainly quartz sand.

[0073] The titanium-containing blast furnace slag contains the following components by mass percentage: CaO: 27.78%; MgO: 7.85%; SiO2: 26.08%; Al2O3: 12.10%; TiO2: 19.68%; Fe2O3: 4.57%; SO2: 1%; K2O: 0.07%; Na2O: 0.08%.

[0074] The process for preparing porous microcrystalline stone in this comparative example is as follows:

[0075] Molten titanium-containing blast furnace slag and quenching agent are heated in a quenching and tempering furnace at 1500°C. o After homogenizing at C for 50 minutes, the sample was cast and then cooled to obtain a microcrystalline stone sample.

[0076] During the slag cooling process, the slag is cooled to 200°C using any of the following methods: natural cooling, forced draft cooling, or in-furnace cooling. o Below C, and the cooling process is set to a cooling rate of 1. o Cooling is performed at C / min.

[0077] Cooled to 200 o Microcrystalline stone samples with a density below C were cut, and sample images are shown below. Figure 6 As shown, Figure 6 Image (a) shows the cross-sectional morphology of the sample, which exhibits relatively few pores and a generally dense structure, with a sample density of 2.94 g / cm³. 3 ; Figure 6 (b) is the XRD pattern of the sample. The main crystalline phases are perovskite and diopside, with a small amount of spinel. The porosity of the sample is less than 1%, which is inconsistent with the expected target of the product design.

[0078] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for producing porous microcrystalline stone from molten titanium-bearing blast furnace slag, characterized by, The application relates to a porous microcrystalline stone and a preparation method thereof. The molten titanium-containing blast furnace slag is directly discharged into a slag pit, the latent heat of the molten titanium-containing blast furnace slag is utilized, crystallization treatment is carried out by controlling cooling conditions, internal sulfur-containing gas and / or water vapor of the molten slag are diffused and escaped, and a blank body with a connected porous structure is obtained; the cooling conditions include single cooling or mixed cooling; the mixed cooling includes the following stages: First stage: slow cooling from the initial temperature of the molten titanium-bearing blast furnace slag to 1100 °C at a cooling rate of 1-5 o C / min. Second stage: slow cooling from 1100 °C to 800 °C at a cooling rate of 1-5 o C / min. Third stage: slow cooling from 800 °C to 600 ° Second stage: from 1100 °C to 600 °C, with a cooling rate of 10-30 o quenching at a rate of 10-30 Third stage: cooling from 600°C at a cooling rate of 5-10 o C / min to 400°C at a cooling rate of 5-10 After the blank body is cooled, cutting and polishing are carried out, and the porous microcrystalline stone is obtained.

2. The method of claim 1, wherein, The chemical composition of the molten titanium-containing blast furnace slag includes the following components in percentage by mass: CaO: 24%-32%, MgO: 5%-15%, SiO2: 20%-32%, Al2O3: 8%-16%, TiO2: 10%-25%, Fe2O3: 0-10%, SO2: 1%-2%, and other components: 0-3%; the other components include any two or more of K2O, Na2O, V2O5 and MnO.

3. The method of claim 1, wherein, The cooling mode of the single cooling is any one of natural cooling, air blast cooling and water spray cooling; the cooling mode of the mixed cooling is a combination of at least two of natural cooling, air blast cooling and water spray cooling.

4. The method of claim 1, wherein, The initial temperature of the molten titanium-containing blast furnace slag is 1450-1550 DEG C.

5. The method of claim 1, wherein, The sulfur-containing gas includes SO2 and / or H2S.

6. A porous microcrystalline stone, characterized in that, The porous microcrystalline stone is prepared by the method.

7. The porous microcrystalline stone according to claim 6, characterized in that, The porosity of the porous microcrystalline stone is 2%-10%, and the compressive strength is 70-100 MPa.

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