Carbonized activated steel slag, preparation method and application in preparation of cement clinker

Abstract

The application discloses carbonized activated steel slag, a preparation method and application in preparation of cement clinker. The preparation method of the carbonized activated steel slag comprises the following steps: activating treatment of the steel slag by using an activating liquid, pH adjustment to 7-8 after first stirring, and then second stirring, filtration, washing, drying, grinding, and sieving to obtain the activated steel slag; and carbonization of the activated steel slag to obtain the carbonized activated steel slag. Through the chemical treatment and CO2 solidification cooperative treatment on the steel slag, the existing form of CaO in the steel slag is changed from multi-element to single-element, the existing form of CaO is optimized, the complex chemical composition of the steel slag is simplified, the steel slag is replaced by limestone as a raw material for calcining cement clinker, the utilization rate of the limestone is reduced, the utilization rate of the steel slag in the field of building materials is improved, and the performance of the cement is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, and particularly relates to carbonized activated steel slag, a preparation method and application in preparation of cement clinker. BACKGROUND

[0002] As the core cementitious material in the construction industry, Portland cement has high dependence on high-quality limestone in the production process, which leads to rapid resource consumption. In view of the finiteness of limestone resources, it is of great significance to develop alternative raw materials to achieve sustainable development for environmental protection and resource conservation.

[0003] Steel slag is an industrial waste produced in the steelmaking process, and has a large stockpile. The chemical composition of steel slag has a large amount of CaO, Fe2O3 and SiO2, which meets the requirements of preparing cement clinker. Therefore, it is theoretically feasible to use steel slag to replace limestone to prepare cement clinker. However, the CaO in steel slag exists in various forms, and the influence mechanism of the formation of clinker minerals is not clear, which leads to insufficient performance of the cement clinker directly prepared from steel slag. SUMMARY

[0004] The present application aims to overcome the above technical deficiencies, and provides a carbonized activated steel slag, a preparation method and application in preparation of cement clinker, to solve the technical problem of insufficient performance of the cement clinker directly prepared from steel slag in the prior art.

[0005] In a first aspect, the present application provides a preparation method of carbonized activated steel slag, comprising the following steps:

[0006] The steel slag is activated by an activation liquid, and after the first stirring, the pH is adjusted to 7-8, and then the second stirring, filtration, washing, drying, grinding and sieving are performed to obtain the activated steel slag.

[0007] The activated steel slag is carbonized to obtain the carbonized activated steel slag; wherein the composition of the activation liquid comprises: inorganic acid, complexing agent and water.

[0008] In a second aspect, the present application provides a carbonized activated steel slag, which is obtained by the preparation method of carbonized activated steel slag provided in the first aspect of the present application.

[0009] In a third aspect, the present application provides application of the above carbonized activated steel slag in preparation of cement clinker.

[0010] In a fourth aspect, the present application provides a cement based on carbonized activated steel slag, which is obtained by mixing the cement clinker provided in the third aspect of the present application and gypsum.

[0011] Compared with the prior art, the present application has the following beneficial effects:

[0012] The present application makes the existing form of CaO in the steel slag change from multi-element to single-element by chemical treatment and CO2 solidification cooperative treatment, optimizes the existing form of CaO, simplifies the complex chemical composition of the steel slag, replaces limestone as a raw material for calcining cement clinker, not only reduces the utilization rate of limestone and improves the utilization rate of steel slag in the building material field, but also effectively improves the performance of cement. The carbonized activated steel slag prepared by the present application has good application prospect in cement clinker and can effectively improve the reaction activity of the cement clinker, thereby improving the mechanical properties thereof. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0014] In a first aspect, the present application provides a preparation method of carbonized activated steel slag, comprising the following steps:

[0015] S1, activating the steel slag by using an activating solution, adjusting the pH to 7-8 after the first stirring, and then performing the second stirring, filtration, washing, drying, grinding and sieving to obtain the activated steel slag;

[0016] S2, carbonizing the activated steel slag to obtain the carbonized activated steel slag; wherein the composition of the activating solution comprises inorganic acid, complexing agent and water.

[0017] In the activating solution of the present application, the inorganic acid can rapidly react with the alkaline oxides in the steel slag, thereby improving the chemical activity of the steel slag; the complexing agent can promote the dissolution of the alkaline components in the steel slag and form a synergistic activation effect with the inorganic acid. At the same time, the steel slag itself has a certain hydration activity, and the complexing agent can form a pH buffer system, which helps to maintain the stability of the pH value during the reaction process and ensure the activation reaction. By using the activating solution to activate the steel slag, on the one hand, the carbonization activity of the steel slag can be effectively improved, because: 1. H + can destroy the inert mineral structure in the steel slag, such as RO phase, thereby enhancing the activity of the steel slag; 2. can increase the specific surface area of the steel slag, which can fully react during carbonization; on the other hand, the Mg-O bond can be destroyed by the activating solution, and Mg is more likely to enter the belite mineral lattice during the subsequent calcination process, thereby improving the activity of the cement clinker based on the carbonized activated steel slag. In addition, compared with directly using the steel slag, the existing form of Fe in the steel slag changes after being treated by the activating solution, which can significantly reduce the Gibbs formation energy of the iron-containing intermediate phase mineral, which is helpful for the generation of the intermediate phase mineral in the subsequent calcination process. In addition, adjusting the pH of the activating system to 7-8 is also beneficial to the subsequent carbonization activation reaction.

[0018] In the embodiment, the chemical composition of the steel slag in step S1 includes, in percentage by weight: CaO 40%-50%, SiO2 10%-15%, Al2O3 1%-4%, Fe2O3 20%-30%, and the balance being loss on ignition and unavoidable impurities (such as MgO, etc.).

[0019] In the embodiment, the particle size of the steel slag in step S1 is ≤75 μm.

[0020] In the embodiment, the inorganic acid in step S1 is at least one of sulfuric acid, hydrochloric acid, and nitric acid.

[0021] In the embodiment, the complexing agent in step S1 is citric acid.

[0022] In the embodiment, the concentration of the inorganic acid in the activating solution in step S1 is 0.009-0.09 mol / L, and the concentration of the complexing agent is 0.0009-0.012 mol / L.

[0023] In some specific embodiments of the present application, the activating solution in step S1 is prepared by mixing an inorganic acid solution with a concentration of 0.01-0.1 mol / L and a complexing agent solution with a concentration of 0.01-0.1 mol / L at a mass ratio of 8-10:1.

[0024] In the embodiment, the mass ratio of the activating solution to the steel slag in step S1 is (50-150):1.

[0025] In the embodiment, the temperature of the first stirring in step S1 is room temperature, and the time of the first stirring is 10-60 min.

[0026] In the embodiment, the pH of the solution is adjusted to 7-8 by using a sodium hydroxide solution in step S1.

[0027] In the embodiment, the concentration of the sodium hydroxide solution is 0.05-0.2 mol / L, and further 0.1 mol / L.

[0028] In the embodiment, the temperature of the second stirring in step S1 is room temperature, and the time of the second stirring is 30-60 min.

[0029] In the embodiment, the mesh size of the screen in the sieving process in step S1 is ≥200 mesh, such as 200 mesh, 300 mesh, 400 mesh, 500 mesh, 1000 mesh, etc.

[0030] In the embodiment, step S2 includes:

[0031] The activated steel slag is dispersed into water, and then carbon dioxide gas is introduced. After the reaction is completed, the carbonated activated steel slag is obtained by drying.

[0032] The mass ratio of water to the activated steel slag is (10-40):1.

[0033] The present application does not limit the type of carbon dioxide-containing gas, and those skilled in the art can select according to the actual situation. For example, the carbon dioxide-containing gas can be carbon dioxide gas with a CO2 volume concentration of >90%, or low-concentration carbon dioxide waste gas with a CO2 volume concentration of 10-90%.

[0034] The aeration rate of the carbon dioxide-containing gas is 0.3-0.6 ml / min.

[0035] The present application does not limit the time of carbonization reaction, and those skilled in the art can select according to the actual situation, and the reaction can be completed. The present application can use phenolphthalein solution, pH meter, conductivity meter and other means to monitor, judge the color, pH value and conductivity change to determine the completion of the reaction. For example, if the pH is ≤7, the reaction is completed.

[0036] In the second aspect, the present application provides a carbonized activated steel slag, which is obtained by the preparation method of the carbonized activated steel slag provided in the first aspect of the present application.

[0037] In the third aspect, the present application provides the use of the above-mentioned carbonized activated steel slag in the preparation of cement clinker.

[0038] Compared with CaCO3 in limestone, the carbonized activated steel slag of the present application has a larger specific surface area and a larger lattice defect, which can effectively promote the formation of cement clinker minerals, reduce the calcination temperature, increase the hydration activity of clinker, and improve the strength of clinker. At the same time, using the carbonized activated steel slag of the present application to prepare cement clinker instead of limestone can also reduce the use rate of limestone.

[0039] In this embodiment, the mineral composition of the cement clinker includes, by weight percentage: C3S 25-50%, C2S 25-50%, C3A 0.5-1%, and C4AF 14-24%.

[0040] In this embodiment, the raw materials of the cement clinker include, by weight: carbonized activated steel slag 8-14 parts, limestone 66-73 parts, aluminum component 7-15 parts, and silicon component 4-13 parts.

[0041] The present application does not limit the type of aluminum component and silicon component, and those skilled in the art can select according to the actual situation, which can provide aluminum and silicon raw materials for the preparation of cement clinker. For example, the aluminum component can be side slope mud, etc.; the silicon component can be high-silicon sandstone, etc.

[0042] The particle size of the raw material of the cement clinker is ≤75 μm.

[0043] In the embodiment, the cement clinker is obtained by mixing and calcining the carbonized activated steel slag, limestone, aluminum component and silicon component, and then quenching.

[0044] The calcination temperature is 1330-1400 ℃, the calcination time is 30-40 min, and the heating rate is 5-20 ℃ / min.

[0045] The quenching method is cooling to below 100 ℃ within 5 min.

[0046] In a fourth aspect, the present application provides a cement based on carbonized activated steel slag, which is obtained by mixing the cement clinker and gypsum.

[0047] In the embodiment, the content of the gypsum is 3%-5% based on the cement based on carbonized activated steel slag.

[0048] In the following examples and comparative examples of the present application, the main chemical components of the ordinary steel slag, limestone, side slope mud material and high-silicon sandstone used are shown in Table 1.

[0049] Table 1

[0050]

[0051] Example 1

[0052] The preparation method of the carbonized activated steel slag provided in the embodiment comprises the following steps:

[0053] (1) The ordinary steel slag with a particle size of ≤75 μm is weighed and placed in a beaker, and an activation solution (prepared by mixing 0.1 M dilute sulfuric acid and 0.1 M citric acid solution according to a mass ratio of 8:1) is added, and the mass ratio of the activation solution to the steel slag is 150:1, and stirring is performed for 10 min.

[0054] (2) After stirring, 0.1 M NaOH is added to the solution until the pH is 7, and then stirring is performed for 30 min.

[0055] (3) After stirring, filtration, washing, drying and grinding are performed, and then the activated steel slag is obtained by passing through a 200-mesh sieve.

[0056] (4) The activated steel slag is placed in a beaker, deionized water is added according to a water-cement mass ratio of 40:1, and CO2 (volume concentration ≥99%) is introduced at a rate of 0.3 ml / min until the pH is 7. The carbonized steel slag is dried to obtain the carbonized activated steel slag.

[0057] The preparation method of the cement clinker provided in the embodiment comprises the following steps:

[0058] (a) According to the designed mineral composition of the cement clinker: C3S 25%, C2S 50%, C3A 1%, C4AF 24%, accurately take the following weight percentage of raw materials: carbonized activated steel slag 14 parts, limestone 66 parts, side slope mud 15 parts, high-silicon sandstone 6 parts.

[0059] (b) After the raw materials are uniformly mixed, they are put into a box-type high-temperature furnace, heated to 1330℃ at 10℃ / min, and kept for 30min, and then cooled to obtain the cement clinker.

[0060] The preparation method of the cement based on the carbonized activated steel slag provided in this embodiment comprises the following steps:

[0061] After the cement clinker prepared in this embodiment is mixed with gypsum and stirred uniformly, the cement based on the carbonized activated steel slag is obtained. The content of the gypsum is 5% of the mass of the cement.

[0062] Example 2

[0063] The preparation method of the carbonized activated steel slag provided in this embodiment comprises the following steps:

[0064] (1) The ordinary steel slag with a particle size of ≤75μm is weighed and put into a beaker, and an activation solution (prepared by mixing 0.01M dilute sulfuric acid and 0.01M citric acid solution according to a mass ratio of 10:1) is added, and the mass ratio of the activation solution to the steel slag is 50:1, and stirred for 60min.

[0065] (2) After stirring, 0.1M NaOH is added to pH 7, and then stirred for 60min.

[0066] (3) After stirring, filtration, washing, drying, and grinding, the activated steel slag is obtained by passing through a 300-mesh sieve.

[0067] (4) The activated steel slag is placed in a beaker, deionized water is added according to a water-cement mass ratio of 10:1, and CO2 (volume concentration ≥99%) is introduced at a rate of 0.6ml / min until the pH is 7. The carbonized steel slag is dried to obtain the carbonized activated steel slag.

[0068] The preparation method of the cement clinker provided in this embodiment comprises the following steps:

[0069] (a) According to the designed mineral composition of the cement clinker: C3S 50%, C2S 25%, C3A 1%, C4AF 24%, accurately take the following weight percentage of raw materials: carbonized activated steel slag 13 parts, limestone 68 parts, side slope mud 15 parts, high-silicon sandstone 4 parts.

[0070] (b) After the raw materials are mixed evenly, they are put into a box-type high-temperature furnace, heated to 1400℃ at a rate of 10℃ / min, and kept at this temperature for 30min, and then cooled to obtain cement clinker.

[0071] The preparation method of the cement based on carbonized activated steel slag provided in this embodiment comprises the following steps:

[0072] The cement based on carbonized activated steel slag is obtained after the cement clinker prepared in this embodiment is mixed and stirred evenly with gypsum. The content of the gypsum is 5% of the mass of the cement.

[0073] Example 3

[0074] The difference between this embodiment and Example 2 is that the design mineral composition of the cement clinker in Example 3 is: C3S 50%, C2S 35.5%, C3A 0.5%, and C4AF 14%, and the weight percentage of the raw materials is: carbonized activated steel slag 8 parts, limestone 73 parts, side slope mud 7 parts, and high-silicon sandstone 12 parts.

[0075] Example 4

[0076] The difference between this embodiment and Example 1 is that the design mineral composition of the cement clinker in Example 4 is: C3S 35.5%, C2S 50%, C3A 0.5%, and C4AF 14%, and the weight percentage of the raw materials is: carbonized activated steel slag 8 parts, limestone 72 parts, side slope mud 7 parts, and high-silicon sandstone 13 parts.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 1 is that the cement clinker is directly prepared using ordinary steel slag in the preparation method of the cement clinker.

[0079] The preparation method of the cement is consistent with that of Example 1.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the cement clinker is directly prepared using activated steel slag in the preparation method of the cement clinker.

[0082] The preparation method of the cement is consistent with that of Example 1.

[0083] Comparative Example 3

[0084] The difference between this comparative example and Example 1 is that the steel slag is directly carbonized without being treated with an activation liquid in the preparation method of the carbonized steel slag, and the specific process is as follows:

[0085] The ordinary steel slag with particle size ≤75 μm was placed in a beaker, deionized water was added according to water-cement mass ratio 40:1, CO2 (volume concentration ≥99%) was introduced at 0.3 ml / min until pH=7.

[0086] The preparation methods of cement clinker and cement were consistent with those of Example 1.

[0087] Comparative Example 4

[0088] The present comparative example is only different from Example 1 in that the preparation method of carbonized activated steel slag does not have the step (2) treatment.

[0089] The preparation methods of cement clinker and cement were consistent with those of Example 1.

[0090] Performance test

[0091] The cement obtained from the present example and comparative examples was molded into samples according to GB / T17671 standard, and the 28d compressive strength of the samples was tested, and the test results are shown in Table 2.

[0092] Table 2

[0093]

[0094] Referring to Table 2, it can be seen from Table 2 that the performance of the cement prepared in Examples 1-4 is obviously better than that of Comparative Examples 1-4, and all meet the 52.5 cement standard, indicating that the carbonized activated steel slag prepared by the method of the present application can effectively stimulate the activity of clinker minerals, and the cement clinker prepared by using the same as raw material has better compressive strength than ordinary steel slag.

[0095] It can be seen from Comparative Examples 1-4 that the performance of the cement prepared in Comparative Examples 2 and 4 is even lower than that of Comparative Example 1, and the performance of the cement prepared in Comparative Example 3 is comparable to that of Comparative Example 1, indicating that only activating treatment of steel slag will destroy the structure of steel slag, which is not conducive to sintering; if only carbonization is performed on steel slag, the sintering is comparable to ordinary steel slag; if the pH is not adjusted after activation, it will also lead to a decrease in the performance of the cement. It can be seen that, by the chemical treatment (activation + alkali) and CO2 solidification synergistic treatment of steel slag in the present application, the performance of the cement can be better improved.

[0096] In summary, the method of the present application can effectively solve the problem that the complex components of steel slag will adversely affect the performance of cement if directly used as a cement raw material; on the other hand, it improves the utilization rate of industrial waste steel slag in the building materials industry, which helps to solve the problems of large amount of steel slag stock and large consumption of high-quality limestone.

[0097] The above description of the specific embodiments of the present application is not intended to limit the scope of the present application. Any other corresponding changes and modifications made according to the technical concept of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. Use of carbonation-activated steel slag in the production of cement clinker, characterized in that, The raw material of the cement clinker comprises carbonized activated steel slag; the carbonized activated steel slag is prepared by the following steps: activating the steel slag by using an activating solution, adjusting the pH to 7-8 after first stirring, and then performing second stirring, filtration, washing, drying, grinding, and sieving to obtain activated steel slag; the activated steel slag is carbonized to obtain carbonized activated steel slag; wherein The composition of the activating solution comprises inorganic acid, complexing agent, and water; The complexing agent is citric acid; The mass ratio of the activating solution to the steel slag is (50-150):

1.

2. Use of carbonation-activated steel slag according to claim 1 for the production of cement clinker, characterized in that, The inorganic acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid; and / or In the activating solution, the concentration of the inorganic acid is 0.009-0.09 mol / L, and the concentration of the complexing agent is 0.0009-0.012 mol / L.

3. Use of the carbonation-activated steel slag according to claim 1 for the preparation of cement clinker, characterized in that, The temperature of the first stirring is room temperature, and the time of the first stirring is 10-60 min; and / or The pH is adjusted to 7-8 by using a sodium hydroxide solution; and / or The temperature of the second stirring is room temperature, and the time of the second stirring is 30-60 min; and / or In the sieving process, the mesh size of the sieve is ≥200 meshes.

4. Use of the carbonation-activated steel slag according to claim 1 for the production of cement clinker, characterized in that, The process of carbonizing the activated steel slag comprises: The activated steel slag is dispersed into water, and then carbon dioxide-containing gas is introduced; after the reaction is completed, drying is performed to obtain carbonized activated steel slag; wherein The mass ratio of the water to the activated steel slag is (10-40):1; and / or The volume concentration of CO2 in the carbon dioxide-containing gas is ≥10%; and / or The aeration rate of the carbon dioxide-containing gas is 0.3-0.6 ml / min; and / or The reaction is determined to be completed by detecting that the pH of the carbonization system is ≤7.

5. Use of carbonation-activated steel slag according to claim 1 for the production of cement clinker, characterized in that, The mineral composition of the cement clinker comprises, by weight percentage, C3S 25-50%, C2S 25-50%, C3A 0.5-1%, and C4AF 14-24%.

6. Use of carbonation-activated steel slag according to claim 1 for the production of cement clinker, characterized in that, The raw material of the cement clinker comprises, by weight part, carbonized activated steel slag 8-14 parts, limestone 66-73 parts, aluminum component 7-15 parts, and silicon component 4-13 parts; wherein The aluminum component is side slope mud; and / or The silicon component is high-silicon sandstone; and / or The particle size of the raw material of the cement clinker is ≤75 μm.

7. Use of carbonation-activated steel slag according to claim 6 for the production of cement clinker, characterized in that, The cement clinker is obtained by mixing and calcining carbonized activated steel slag, limestone, aluminum component, and silicon component, and then quenching; wherein The calcination temperature is 1330-1400 °C, the calcination time is 30-40 min, and the heating rate is 5-20 °C / min.

8. A cement based on carbonation activated steel slag, characterized in that, The cement based on carbonized activated steel slag is obtained by mixing the cement clinker and gypsum; The raw material of the cement clinker comprises carbonized activated steel slag; the carbonized activated steel slag is prepared by the following steps: activating the steel slag by using an activating solution, adjusting the pH to 7-8 after first stirring, and then performing second stirring, filtration, washing, drying, grinding, and sieving to obtain activated steel slag; the activated steel slag is carbonized to obtain carbonized activated steel slag; wherein The composition of the activating solution comprises inorganic acid, complexing agent, and water; The complexing agent is citric acid. The mass ratio of the activating liquid to the steel slag is (50-150):1.

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