Steel and iron slag composite cementing material containing red mud and preparation method of steel and iron slag composite cementing material

Abstract

The invention relates to the technical field of cement materials, in particular to a red-mud-containing steel slag composite cementing material and a preparation method thereof.The method comprises the steps that red mud, slag, steel slag, desulfurized gypsum and sulphoaluminate cement clinker are subjected to dry mixing to obtain an initial mixture; determining whether the excitation capability of the potential hydration activity reaches the standard or not based on the alkaline matching index, and adjusting the weight part of the sulphoaluminate cement clinker; adding a composite exciting agent to obtain activated slurry; determining whether the dispersion effect of the flocculation structure of the initial mixture is qualified or not based on the dispersion index of the flocculation structure, and adjusting the ball milling rotating speed; adding a polymer emulsion to obtain an initial composite cementing material; determining whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified or not based on the synergistic enhancement index, and adjusting the dripping rate of the polymer emulsion; the steel slag composite cementing material containing the red mud is obtained. The preparation stability of the red mud-containing steel slag composite cementing material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cementitious materials, and particularly relates to a steel slag composite cementitious material containing red mud and a preparation method thereof. BACKGROUND

[0002] With the rapid development of industry, the storage and treatment of bulk industrial solid waste has become a global environmental challenge. Red mud is a strong alkaline waste residue produced in the production process of alumina, containing a large amount of iron, aluminum, silicon, sodium and other oxides. Its strong alkalinity and heavy metal components pose a serious threat to the environment and groundwater. At present, the comprehensive utilization rate of red mud is very low, and it is mainly stored. Steel slag, including slag and steel slag, is the main solid waste of the steel industry. Slag has potential cementitious activity and can be used as a cement admixture after activation. Steel slag has complex composition and low activity, and its utilization rate is also low. The collaborative utilization of red mud and steel slag to prepare cementitious materials is an important way to realize the high-value resource utilization of red mud and steel slag. The existing technology usually simply mixes these solid wastes with a small amount of activator in order to utilize the alkalinity of red mud to activate the activity of slag and steel slag.

[0003] Chinese patent application publication No. CN118930155A discloses a full solid waste cementing material and a preparation method and application thereof, which comprises: a cementitious material and tailings sand; wherein the cementitious material comprises the following components in parts by weight: slag powder 30-80 parts, steel slag powder 15-30 parts, fly ash 10-25 parts, desulfurization gypsum 2-20 parts, red mud 1-10 parts, and activated raw material 3-10 parts; the mass ratio of the cementitious material to the tailings sand is 1:8-13.

[0004] However, the prior art has the following problems: relying on preset process parameters, not monitoring and controlling the compatibility of polymers and inorganic systems, resulting in low early strength of the red mud-containing steel slag composite cementitious material, thereby causing the problem of low preparation stability of the red mud-containing steel slag composite cementitious material. SUMMARY

[0005] Therefore, the present application provides a red mud-containing steel slag composite cementitious material and a preparation method thereof, to overcome the problem in the prior art that relying on preset process parameters, not monitoring and controlling the compatibility of polymers and inorganic systems, resulting in low early strength of the red mud-containing steel slag composite cementitious material, thereby causing the problem of low preparation stability of the red mud-containing steel slag composite cementitious material.

[0006] To achieve the above-mentioned purpose, the present application provides a preparation method of a red mud-containing steel slag composite cementitious material, comprising:

[0007] The red mud, slag, steel slag, desulfurization gypsum and sulphoaluminate cement clinker are dry mixed under preset batching conditions to obtain an initial mixture;

[0008] obtaining an X-ray diffraction pattern of the initial mixture, determining a basicity matching index based on the X-ray diffraction pattern, to determine whether the excitation ability of the basicity of the red mud to the potential hydration activity of the slag and the steel slag meets the standard, and adjusting the weight fraction of the sulphate aluminate cement clinker according to the ratio of the basicity matching index to a preset basicity matching index;

[0009] adding a composite activator to the initial mixture with the excitation ability meeting the standard, and treating under a preset activation condition to obtain an activated slurry;

[0010] obtaining a rheological curve of the activated slurry, determining a flocculation structure dispersion index based on the rheological curve, to determine whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified, and adjusting the ball milling speed according to a flocculation structure dispersion index difference between a preset flocculation structure dispersion index and the flocculation structure dispersion index;

[0011] adding a polymer emulsion to the activated slurry with the dispersion effect qualified, and blending modification under a preset stirring condition to obtain an initial composite cementitious material;

[0012] obtaining the compressive strength data of the initial composite cementitious material after curing, determining a synergistic enhancement index based on the compressive strength data, to determine whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified, and adjusting the dropping speed of the polymer emulsion according to a relative difference between a preset synergistic enhancement index and the synergistic enhancement index;

[0013] under the condition that the synergistic enhancement effect is qualified, after drying and grinding, a red mud-containing steel slag composite cementitious material is obtained.

[0014] Further, the determination that the excitation ability of the basicity of the red mud to the potential hydration activity of the slag and the steel slag does not meet the standard is based on the result that the basicity matching index is less than or equal to a preset basicity matching index.

[0015] Further, the process of obtaining the basicity matching index comprises:

[0016] extracting the red mud integral intensity of the sodalite characteristic peak in the red mud;

[0017] extracting the steel slag integral intensity of the glass body hump in the slag and the steel slag;

[0018] extracting the total integral intensity of the X-ray diffraction pattern within a preset range;

[0019] the basicity matching index is the product of the red mud integral intensity and the steel slag integral intensity divided by the square of the total integral intensity.

[0020] Further, the process of adjusting the weight fraction of the aluminate cement clinker comprises:

[0021] determining, based on a comparison result that the ratio is less than or equal to a preset ratio, that the weight percentage of the sulphoaluminate cement clinker is increased by a first preset weight percentage adjustment coefficient;

[0022] Or, determining, based on a comparison result that the ratio is greater than a preset ratio, that the weight percentage of the sulphoaluminate cement clinker is increased by a second preset weight percentage adjustment coefficient.

[0023] Further, determining, based on a comparison result that the flocculation structure dispersion index is less than or equal to a preset flocculation structure dispersion index, that the dispersion effect of the composite activator on the flocculation structure of the initial mixture is unqualified, wherein,

[0024] The flocculation structure dispersion index is determined according to a thixotropic ring area of a thixotropic ring of the activated slurry and a theoretical thixotropic ring area.

[0025] Further, the process of adjusting the ball mill rotating speed comprises:

[0026] Determining, based on a comparison result that the structure dispersion index difference value is less than or equal to a preset difference value, that the ball mill rotating speed is increased by a first preset rotating speed adjustment coefficient.

[0027] Or, determining, based on a comparison result that the structure dispersion index difference value is greater than a preset difference value, that the ball mill rotating speed is increased by a second preset rotating speed adjustment coefficient.

[0028] Further, determining, based on a comparison result that the synergistic enhancement index is less than or equal to a preset synergistic enhancement index, that the synergistic enhancement effect of the polymer emulsion on the activated slurry is unqualified, wherein,

[0029] The synergistic enhancement index is determined according to an average value of the initial composite cement compressive strength and an average value of the compressive strength of the Portland cement test block.

[0030] Further, the process of adjusting the dropping speed of the polymer emulsion comprises:

[0031] Determining, based on a comparison result that the relative difference is less than or equal to a preset relative difference, that the dropping speed is decreased by a first preset dropping speed adjustment coefficient.

[0032] Or, determining, based on a comparison result that the relative difference is greater than a preset relative difference, that the dropping speed is decreased by a second preset dropping speed adjustment coefficient.

[0033] Further, the composite activator is sodium sulfate and silica ash.

[0034] The application further provides a composite cementitious material containing red mud and steel slag, comprising: red mud, slag, steel slag, desulfurization gypsum, sulphoaluminate cement clinker, composite activator and polymer emulsion.

[0035] Compared with the prior art, the present application has the beneficial effects that the alkali matching index is used to determine whether the alkali of the red mud meets the standard for the potential hydration activity of the slag and the steel slag, and the weight fraction of the sulphoaluminate cement clinker is adjusted when the standard is not met; the flocculation structure dispersion index is used to determine whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified, and the ball milling speed is adjusted when the effect is not qualified; the synergistic enhancement index is used to determine whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified, and the dropping speed of the polymer emulsion is adjusted when the effect is not qualified; the X-ray diffraction pattern can clearly present the crystal structure information of each mineral in the mixture, and the reaction activity of different mineral crystal structures in the alkali environment is different; when the alkali matching index does not meet the standard, it indicates that the alkali of the red mud is insufficient to activate the slag and the steel slag, and the weight fraction of the sulphoaluminate cement clinker is adjusted at this time because the sulphoaluminate cement clinker can provide additional alkali components to change the alkali environment of the mixture, so as to more accurately activate the hydration activity of the slag and the steel slag, improve the early strength and hydration reaction degree of the composite cementitious material; the rheological curve reflects the flow characteristics of the activated slurry under different shear forces, and the flocculation structure dispersion index can quantitatively describe the dispersion degree of the flocculation structure in the slurry; if the dispersion effect is not qualified, the ball milling speed is adjusted because the ball milling process can mechanically break and disperse the particles in the slurry; the appropriate ball milling speed can provide enough energy to break the unreasonable flocculation structure, make the particles more uniformly dispersed in the slurry, improve the fluidity and uniformity of the slurry, and thus improve the performance of the composite cementitious material; the compressive strength data directly reflects the mechanical properties of the composite cementitious material, and the synergistic enhancement index comprehensively considers the contribution of the polymer emulsion and the activated slurry to the strength improvement of the material; when the synergistic enhancement effect is not qualified, the dropping speed of the polymer emulsion is adjusted because the dropping speed will affect the dispersion uniformity of the polymer emulsion in the activated slurry and the combination degree with the activated slurry; the appropriate dropping speed can make the polymer emulsion better wrap around the particle surface to form a uniform polymer film, enhance the bonding force between the particles, and thus improve the compressive strength and durability of the composite cementitious material.

[0036] Further, the alkali matching index is used to determine whether the activation ability of the red mud for the potential hydration activity of the slag and the steel slag meets the standard, and the weight fraction of the sulphoaluminate cement clinker is increased by a preset weight fraction adjustment coefficient when the standard is not met; the integral intensity of the sodalite characteristic peak in the red mud reflects the activity degree of the alkali substances in the red mud, and the integral intensity of the glass body hump of the slag and the steel slag reflects the basis of their potential hydration activity; when the activation environment provided by the alkali of the red mud is insufficient to fully activate the hydration activity of the slag and the steel slag, the weight fraction of the sulphoaluminate cement clinker is increased by different coefficients because the sulphoaluminate cement clinker can provide additional alkali ions to change the alkali environment of the system, accurately control the alkali of the system, and make the hydration reaction of the slag and the steel slag more sufficient, thereby improving the hydration degree and early strength of the composite cementitious material.

[0037] Further, the present application judges whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified by the flocculation structure dispersion index, and if not, the ball mill rotation speed is increased by the preset rotation speed adjustment coefficient. The thixotropic ring area reflects the tightness and stability of the flocculation structure in the activated slurry, and the theoretical thixotropic ring area represents the ideal state when the flocculation structure is completely broken down. The flocculation structure dispersion index is presented by the ratio of the two, and the dispersion degree of the composite activator on the flocculation structure is directly reflected. When the flocculation structure dispersion index is less than or equal to the preset value, it indicates that the composite activator cannot fully disperse the flocculation structure, and at this time the particle agglomeration in the slurry is serious, which will affect the uniformity and performance of the subsequent composite cementitious material. Adjusting the ball mill rotation speed is because the ball milling process can provide mechanical force to break the flocculation structure, which can more effectively disperse the particles, and can precisely control the ball mill rotation speed to make the particles in the slurry reach a suitable dispersion state, improve the uniformity and fluidity of the composite cementitious material, and further optimize its mechanical properties and durability, thereby improving the overall quality of the material from the micro to the macro level.

[0038] Further, the present application judges whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified by the flocculation structure dispersion index, and if not, the ball mill rotation speed is increased by the preset rotation speed adjustment coefficient. The thixotropic ring area reflects the tightness and stability of the flocculation structure in the activated slurry, and the theoretical thixotropic ring area represents the ideal state when the flocculation structure is completely broken down. The flocculation structure dispersion index is presented by the ratio of the two, and the dispersion degree of the composite activator on the flocculation structure is directly reflected. When the flocculation structure dispersion index is less than or equal to the preset value, it indicates that the composite activator cannot fully disperse the flocculation structure, and at this time the particle agglomeration in the slurry is serious, which will affect the uniformity and performance of the subsequent composite cementitious material. Adjusting the ball mill rotation speed is because the ball milling process can provide mechanical force to break the flocculation structure, which can more effectively disperse the particles, and can precisely control the ball mill rotation speed to make the particles in the slurry reach a suitable dispersion state, improve the uniformity and fluidity of the composite cementitious material, and further optimize its mechanical properties and durability, thereby improving the overall quality of the material from the micro to the macro level. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The flowchart of the preparation method of the steel slag composite cementitious material containing red mud according to the embodiments of the present application;

[0040] Figure 2A flow chart for determining whether the excitation ability of the alkalinity of the red mud to the potential hydration activity of the slag and the steel slag meets the standard for the embodiment of the present application;

[0041] Figure 3 A flow chart for determining whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified for the embodiment of the present application;

[0042] Figure 4 A flow chart for determining whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified for the embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the objects and advantages of the present application clearer, the present application will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the protection scope of the present application.

[0044] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application and not to limit the protection scope of the present application.

[0045] It should be pointed out that the data in the present embodiment are obtained by comprehensive analysis and evaluation of historical detection data and corresponding historical detection results in the three months before the present detection by the present application. Those skilled in the art can understand that the determination method of the present application for a single parameter can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, to use weighted summation to obtain the value as the preset standard parameter, to substitute each historical data into a specific formula and to obtain the value by using the formula as the preset standard parameter, or other selection methods, as long as the present application can clearly define different specific situations in the single determination process by the obtained value.

[0046] Please refer to Figure 1 shown, which is a flow chart of a preparation method of a steel slag composite cementitious material containing red mud according to an embodiment of the present application.

[0047] The preparation method of the steel slag composite cementitious material containing red mud according to an embodiment of the present application comprises:

[0048] Step S1, dry mixing red mud, slag, steel slag, desulfurization gypsum and sulphoaluminate cement clinker under preset batching conditions to obtain an initial mixture;

[0049] Step S2, obtaining an X-ray diffraction pattern of the initial mixture, determining an alkalinity matching index based on the X-ray diffraction pattern to determine whether the excitation ability of the alkalinity of the red mud to the potential hydration activity of the slag and the steel slag meets the standard, and adjusting the weight fraction of the sulphoaluminate cement clinker according to the ratio of the alkalinity matching index to a preset alkalinity matching index.

[0050] Step S3, adding a composite activator to the initial mixture with qualified activation capacity and processing the initial mixture under preset activation conditions to obtain an activated slurry;

[0051] Step S4, obtaining a rheological curve of the activated slurry, determining a flocculation structure dispersion index based on the rheological curve, determining whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified, and adjusting the ball milling rotating speed according to a structure dispersion index difference between a preset flocculation structure dispersion index and the flocculation structure dispersion index;

[0052] Step S5, adding a polymer emulsion to the activated slurry with qualified dispersion effect and blending modification under preset stirring conditions to obtain an initial composite cementitious material;

[0053] Step S6, obtaining compressive strength data of the initial composite cementitious material after curing, determining a synergistic enhancement index based on the compressive strength data, determining whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified, and adjusting a dropping speed of the polymer emulsion according to a relative difference between a preset synergistic enhancement index and the synergistic enhancement index;

[0054] Step S7, under the condition that the synergistic enhancement effect is qualified, drying and grinding to obtain a steel slag composite cementitious material containing red mud.

[0055] Specifically, the application determines whether the alkali of red mud meets the standard of potential hydration activity of slag and steel slag by the alkali matching index, adjusts the weight fraction of sulphoaluminate cement clinker when it does not meet the standard, determines whether the dispersion effect of the initial mixture flocculation structure by the flocculation structure dispersion index, adjusts the ball milling speed when it does not meet the standard, determines whether the synergistic enhancement effect of the polymer emulsion and the activated slurry by the synergistic enhancement index, adjusts the polymer emulsion drop rate when it does not meet the standard, and the X-ray diffraction pattern can clearly present the crystal structure information of each mineral in the mixture, the reaction activity of different mineral crystal structures in the alkaline environment is different, when the alkali matching index does not meet the standard, it indicates that the alkali of red mud is insufficient to stimulate slag and steel slag, at this time, the weight fraction of sulphoaluminate cement clinker is adjusted, because sulphoaluminate cement clinker can provide additional alkaline components to change the alkaline environment of the mixture, thereby more accurately stimulating the hydration activity of slag and steel slag, improving the early strength and hydration reaction degree of the composite cementitious material, the rheological curve reflects the flow characteristics of the activated slurry under different shear forces, and the flocculation structure dispersion index can quantitatively describe the dispersion degree of the flocculation structure in the slurry, if the dispersion effect is not qualified, the ball milling speed is adjusted because the ball milling process can mechanically break and disperse the particles in the slurry. The appropriate ball milling speed can provide enough energy to break the unreasonable flocculation structure, make the particles more uniformly dispersed in the slurry, improve the fluidity and uniformity of the slurry, and thus improve the performance of the composite cementitious material, the compressive strength data directly reflects the mechanical properties of the composite cementitious material, and the synergistic enhancement index comprehensively considers the contribution of the polymer emulsion and the activated slurry to the strength improvement of the material, when the synergistic enhancement effect is not qualified, the drop rate of the polymer emulsion is adjusted because the drop rate will affect the dispersion uniformity of the polymer emulsion in the activated slurry and the combination degree with the activated slurry, the appropriate drop rate can make the polymer emulsion better wrapped on the particle surface, form a uniform polymer film, and enhance the bonding force between the particles, thereby improving the compressive strength and durability of the composite cementitious material.

[0056] The application also provides a red mud-containing steel slag composite cementitious material, which comprises:

[0057] Red mud, slag, steel slag, desulfurization gypsum, sulphoaluminate cement clinker, composite activator and polymer emulsion.

[0058] In the embodiment of the application, the red mud-containing steel slag composite cementitious material is composed of, by weight fraction: 15-25 parts of red mud, preferably 20 parts; 35-45 parts of slag, preferably 40 parts; 20-30 parts of steel slag, preferably 25 parts; 6-9 parts of desulfurization gypsum, preferably 7 parts; 5-8 parts of sulphoaluminate cement clinker, preferably 6 parts; 1-5 parts of composite activator, preferably 3 parts; and 3-5 parts of polymer emulsion (calculated by solid fraction), preferably 4 parts.

[0059] In the embodiment of the present application, the composite activator is sodium sulfate and silica ash.

[0060] Specifically, in the step S1, the preset batching condition comprises: the dry mixing temperature is room temperature (25℃±5℃), the dry mixing time is 10-20 min, preferably 15 min, the dry mixing speed is 200-300 rpm, preferably 250 rpm, and the dry mixing of the red mud, the slag, the steel slag, the desulfurization gypsum and the sulphoaluminate cement clinker is completed by a planetary mixer.

[0061] Specifically, the initial mixture is sampled in the embodiment of the present application, and an X-ray diffraction pattern is obtained by scanning the sample using an X-ray diffractometer (XRD), the scanning range is 5°-70° (2θ), and the scanning rate is 2° / min, and the relative intensity ratio is determined according to the characteristic peaks of the red mud (the characteristic peak of Fe2O3 in the red mud is selected, 2θ≈33.2°) and the characteristic peaks of the slag and the steel slag (the characteristic peak of C2S in the slag and the steel slag is selected, 2θ≈32.1°) in the pattern.

[0062] Referring to Figure 2 It is a flow chart for determining whether the activation capacity of the alkalinity of the red mud on the potential hydration activity of the slag and the steel slag meets the standard.

[0063] Specifically, whether the activation capacity of the alkalinity of the red mud on the potential hydration activity of the slag and the steel slag meets the standard is determined according to the comparison result of the alkalinity matching index and the preset alkalinity matching index.

[0064] When the alkalinity matching index is less than or equal to the preset alkalinity matching index, it is determined that the activation capacity of the alkalinity of the red mud on the potential hydration activity of the slag and the steel slag does not meet the standard.

[0065] When the alkalinity matching index is greater than the preset alkalinity matching index, it is determined that the activation capacity of the alkalinity of the red mud on the potential hydration activity of the slag and the steel slag meets the standard.

[0066] In the embodiment of the present application, the preset alkalinity matching index is 0.9, and the preset alkalinity matching index is obtained by averaging the alkalinity matching indexes of a plurality of red muds whose activation capacity of the alkalinity on the potential hydration activity of the slag and the steel slag meets the standard, but the above value is not limited thereto, and the value can be adjusted according to actual needs by those skilled in the art.

[0067] In the implementation process, the process of obtaining the alkalinity matching index is as follows: the red mud integral intensity of the sodalite characteristic peak in the red mud is extracted; the steel slag integral intensity of the glass hump of the slag and the steel slag is extracted; the total integral intensity in the range of 5° to 70° in the XRD pattern is extracted; and the alkalinity matching index is the product of the red mud integral intensity and the steel slag integral intensity divided by the square of the total integral intensity.

[0068] Specifically, in the case that the alkali of the red mud fails to meet the requirement of the excitation ability of the potential hydration activity of the slag and the steel slag, the weight percentage of the sulphoaluminate cement clinker is adjusted according to the comparison result of the ratio of the alkali matching index to the preset alkali matching index and the preset ratio.

[0069] When the ratio is less than or equal to the preset ratio, the weight percentage of the sulphoaluminate cement clinker is increased to a corresponding value by a first preset weight percentage adjustment coefficient.

[0070] When the ratio is greater than the preset ratio, the weight percentage of the sulphoaluminate cement clinker is increased to a corresponding value by a second preset weight percentage adjustment coefficient.

[0071] The ratio is the ratio of the alkali matching index to the preset alkali matching index.

[0072] In the embodiment of the present application, the preset ratio is 0.35, but the above value is not limited thereto, and the skilled person in the art can also adjust the value according to actual needs.

[0073] In the embodiment of the present application, the increased weight percentage is the product of the weight percentage and the preset weight percentage adjustment coefficient, the preset weight percentage adjustment coefficient includes the first preset weight percentage adjustment coefficient with a value of 1.1 and the second preset weight percentage adjustment coefficient with a value of 1.2, in order to ensure that the adjusted weight percentage meets the actual demand, the adjustment range should not be too large, so the adjustment coefficient is set to control the adjustment range.

[0074] Specifically, the present application determines whether the red mud meets the requirement of the excitation ability of the potential hydration activity of the slag and the steel slag by the alkali matching index, and increases the weight percentage of the sulphoaluminate cement clinker by the preset weight percentage adjustment coefficient if it fails to meet the requirement, the integral intensity of the sodalite characteristic peak in the red mud reflects the activity degree of the alkali in the red mud, and the integral intensity of the glass body hump of the slag and the steel slag embodies the basis of their potential hydration activity, when the excitation environment provided by the alkali of the red mud is insufficient, it is difficult to fully excite the hydration activity of the slag and the steel slag, and the weight percentage of the sulphoaluminate cement clinker is increased by different coefficients, because the sulphoaluminate cement clinker can provide additional alkali ions to change the alkali environment of the system, accurately control the alkali of the system, make the hydration reaction of the slag and the steel slag more sufficient, and improve the hydration degree and early strength of the composite cementitious material.

[0075] Specifically, in the step S3, the preset activation conditions include that the mechanical activation adopts a ball mill, the ball-to-material ratio is 5:1, the ball milling time is 30-60 min, preferably 45 min, and the ball milling speed is 400-600 rpm, preferably 500 rpm; the chemical activation temperature is 60-80℃, preferably 70℃, and the activation time is 2-4h, preferably 3h.

[0076] Specifically, the present embodiment samples from the activated slurry, measures the rheological curve at 25℃ using a rotational rheometer, and the shear rate is linearly increased from 0.1 s -1 to 100 s -1 , and then linearly decreased back to 0.1 s -1 , to obtain the thixotropic loop of the activated slurry.

[0077] Please refer to Figure 3 , which is a flow chart for determining whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified according to the present embodiment of the application.

[0078] Specifically, the present embodiment determines whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified according to the comparison result of the flocculation structure dispersion index and the preset flocculation structure dispersion index;

[0079] When the flocculation structure dispersion index is less than or equal to the preset flocculation structure dispersion index, it is determined that the dispersion effect of the composite activator on the flocculation structure of the initial mixture is unqualified;

[0080] When the flocculation structure dispersion index is greater than the preset flocculation structure dispersion index, it is determined that the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified.

[0081] In the present embodiment, the preset flocculation structure dispersion index is 0.85, and the preset flocculation structure dispersion index is obtained by averaging the flocculation structure dispersion indexes of a plurality of composite activators whose dispersion effects on the flocculation structure of the initial mixture are qualified, but the above-mentioned value is not limited thereto, and the skilled person in the art can also adjust the value according to actual needs.

[0082] In the implementation process, the process of obtaining the flocculation structure dispersion index is to calculate the thixotropic loop area of the activated slurry; the flocculation structure breakdown index is the ratio of the thixotropic loop area to the theoretical thixotropic loop area, wherein the theoretical thixotropic loop area is set to 1000 Pa·s -1 , and the theoretical thixotropic loop area is determined by calibration experiment, which represents the ideal area when the flocculation structure is completely broken down.

[0083] Specifically, under the condition that the dispersion effect of the composite activator on the flocculation structure of the initial mixture is unqualified, the present embodiment determines to adjust the ball mill rotation speed according to the comparison result of the structure dispersion index difference between the preset flocculation structure dispersion index and the flocculation structure dispersion index and the preset difference value;

[0084] When the structure dispersion index difference is less than or equal to the preset difference value, it is determined to increase the ball mill rotation speed to the corresponding value by the first preset rotation speed adjustment coefficient;

[0085] When the structure dispersion index difference value is greater than the preset difference value, it is determined that the ball mill rotation speed is increased to a corresponding value by a second preset rotation speed adjustment coefficient;

[0086] The structure dispersion index difference value is a difference value between a preset flocculation structure dispersion index and the flocculation structure dispersion index.

[0087] In the embodiment of the application, the preset difference value is 0.2, but the above-mentioned value is not limited thereto, and the value can be adjusted according to actual needs by those skilled in the art.

[0088] In the embodiment of the application, the increased ball mill rotation speed is a product of the ball mill rotation speed and a preset rotation speed adjustment coefficient, the preset rotation speed adjustment coefficient includes a first preset rotation speed adjustment coefficient with a value of 1.15 and a second preset rotation speed adjustment coefficient with a value of 1.25, and the increased ball mill rotation speed is rounded to an integer value. In order to ensure that the adjusted ball mill rotation speed meets the actual needs, the adjustment range should not be too large, so the adjustment coefficient is correspondingly set to control the adjustment range.

[0089] Specifically, the application determines whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified by the flocculation structure dispersion index, and if not, the ball mill rotation speed is increased by a preset rotation speed adjustment coefficient. The thixotropic ring area reflects the tightness and stability of the flocculation structure in the activated slurry, and the theoretical thixotropic ring area represents the ideal state when the flocculation structure is completely broken. The flocculation structure dispersion index is presented by the ratio of the two, which directly reflects the dispersion degree of the composite activator on the flocculation structure. When the flocculation structure dispersion index is less than or equal to the preset value, it indicates that the composite activator has not fully dispersed the flocculation structure, and at this time, the particle agglomeration in the slurry is serious, which will affect the uniformity and performance of the subsequent composite cementitious material. Adjusting the ball mill rotation speed can provide mechanical force to break the flocculation structure in the ball milling process, which can more effectively disperse the particles and precisely control the ball mill rotation speed to make the particles in the slurry reach a suitable dispersion state, improve the uniformity and fluidity of the composite cementitious material, and further optimize its mechanical properties and durability, thereby improving the overall quality of the material from the micro to the macro level.

[0090] Specifically, in step S5, the preset stirring conditions include: a stirring speed of 500-800 rpm, preferably 650 rpm, a stirring time of 10-30 min, preferably 20 min, and a stirring temperature of room temperature.

[0091] Specifically, in the embodiment of the application, the initial composite cementitious material is poured into a test block with a size of 40mm×40mm×160mm, and the compressive strength is tested after 3 days of curing under standard curing conditions, wherein the standard curing conditions are a temperature of 20±1℃ and a relative humidity of ≥95%.

[0092] Please refer to Figure 4As shown, it is a flow chart for determining whether the synergistic reinforcing effect of the polymer emulsion and the activated slurry is qualified according to the embodiments of the present application.

[0093] Specifically, according to the comparison result of the synergistic reinforcing index and the preset synergistic reinforcing index, the embodiments of the present application determine whether the synergistic reinforcing effect of the polymer emulsion and the activated slurry is qualified;

[0094] When the synergistic reinforcing index is less than or equal to the preset synergistic reinforcing index, it is determined that the synergistic reinforcing effect of the polymer emulsion and the activated slurry is unqualified;

[0095] When the synergistic reinforcing index is greater than the preset synergistic reinforcing index, it is determined that the synergistic reinforcing effect of the polymer emulsion and the activated slurry is qualified.

[0096] In the embodiments of the present application, the preset synergistic reinforcing index is 0.87, which is obtained by averaging the synergistic reinforcing indexes of a plurality of polymer emulsions and activated slurries whose synergistic reinforcing effects are qualified, but the above-mentioned value is not limited thereto, and the person skilled in the art can also adjust the value according to actual needs.

[0097] In the implementation process, the synergistic reinforcing index is the ratio of the average value of the 3-day compressive strength of the test block to the average value of the 3-day compressive strength of the Portland cement reference block under the same curing conditions.

[0098] Specifically, under the condition that the synergistic reinforcing effect of the polymer emulsion and the activated slurry is determined to be unqualified, the embodiments of the present application determine to adjust the drop rate of the polymer emulsion according to the comparison result of the relative difference between the preset synergistic reinforcing index and the synergistic reinforcing index and the preset relative difference;

[0099] When the relative difference is less than or equal to the preset relative difference, it is determined to reduce the drop rate to a corresponding value by a first preset drop rate adjustment coefficient;

[0100] When the relative difference is greater than the preset relative difference, it is determined to reduce the drop rate to a corresponding value by a second preset drop rate adjustment coefficient;

[0101] The relative difference is the relative difference between the preset synergistic reinforcing index and the synergistic reinforcing index, that is, the ratio of the absolute value of the difference between the preset synergistic reinforcing index and the actual synergistic reinforcing index to the preset synergistic reinforcing index.

[0102] In the embodiments of the present application, the preset relative difference is 0.5, but the above-mentioned value is not limited thereto, and the person skilled in the art can also adjust the value according to actual needs.

[0103] In the embodiment of the present application, the reduced dropwise adding rate is the product of the dropwise adding rate and a preset dropwise adding rate adjustment coefficient, and the preset dropwise adding rate adjustment coefficient includes a first preset dropwise adding rate adjustment coefficient with a value of 0.9 and a second preset dropwise adding rate adjustment coefficient with a value of 0.8. In order to ensure that the adjusted dropwise adding rate meets the actual demand, the adjustment range should not be too large, so the adjustment range is controlled by setting the adjustment coefficient.

[0104] Specifically, the present application determines whether the synergistic reinforcing effect of the polymer emulsion and the activated slurry is qualified by the synergistic reinforcing index. If not, the dropwise adding rate of the polymer emulsion is reduced by a preset dropwise adding rate adjustment coefficient. The compressive strength of the test block reflects the early mechanical properties of the material after the synergistic effect of the polymer emulsion and the activated slurry, and the compressive strength of the Portland cement preparation reference block under the same curing condition provides a standard reference. The synergistic reinforcing index is directly presented by the ratio of the two, intuitively presenting the pros and cons of the synergistic reinforcing effect of the polymer emulsion and the activated slurry. When the synergistic reinforcing index is less than or equal to a preset value, it means that the synergistic effect of the two does not meet the expectation, and the early strength development of the material is insufficient, which may affect the subsequent use performance and durability. Adjusting the dropwise adding rate of the polymer emulsion is because the dropwise adding rate directly affects the dispersion degree and reaction degree of the polymer emulsion in the activated slurry, indicating that the deviation degree of the synergistic reinforcing effect is relatively small. Reducing the dropwise adding rate can make the polymer emulsion more uniformly dispersed in the activated slurry, avoid local high or low concentration, and promote the full reaction of the two. If the relative difference is greater than the preset relative difference, it means that the deviation of the synergistic reinforcing effect is large. Reducing the dropwise adding rate can greatly adjust the amount of polymer emulsion added, re-optimize the ratio of the polymer emulsion and the activated slurry, and make the two better synergistic effect. Precise control of the dropwise adding rate of the polymer emulsion can improve the synergistic reinforcing effect, improve the early strength and overall performance of the material, optimize the material structure from the micro-reaction level, and improve the material quality.

[0105] Specifically, in the embodiment of the present application, under the condition that the synergistic reinforcing effect of the initial composite cementitious material is qualified, after drying and grinding, a steel slag composite cementitious material containing red mud is obtained.

[0106] Example 1:

[0107] Take 20 parts of red mud, 40 parts of slag, 25 parts of steel slag, 7 parts of desulfurization gypsum, and 6 parts of sulfoaluminate cement clinker by mass fraction, dry mix at a temperature of 25℃, a dry mixing speed of 250 rpm, and a dry mixing time of 15 min to obtain an initial mixture; add 3 parts of a composite activator to the initial mixture and mechanically activate it at a ball milling speed of 500 rpm and a ball milling time of 45 min, and then activate it at a chemical activation temperature of 70℃ and an activation time of 3 h to obtain an activated slurry; add 4 parts of a polymer emulsion to the activated slurry and stir at a stirring speed of 650 rpm, a stirring time of 20 min, and a stirring temperature of room temperature to obtain an initial composite cementitious material; after drying and grinding, obtain a red mud-containing steel slag composite cementitious material.

[0108] Example 2:

[0109] In this example, except for 25 parts of red mud, 35 parts of slag, 30 parts of steel slag, 5 parts of a composite activator, and 5 parts of a polymer emulsion, the rest is the same as in Example 1.

[0110] Example 3:

[0111] In this example, except for 15 parts of red mud, 45 parts of slag, 20 parts of steel slag, 1 part of a composite activator, and 3 parts of a polymer emulsion, the rest is the same as in Example 1.

[0112] Example 4:

[0113] In this example, except for a ball milling speed of 600 rpm, the rest is the same as in Example 1.

[0114] Example 5:

[0115] In this example, except for a chemical activation temperature of 80℃, the rest is the same as in Example 1.

[0116] Comparative Example 1:

[0117] In this example, except for not containing a polymer emulsion, the rest is the same as in Example 1.

[0118] Comparative Example 2:

[0119] In this example, except for a ball milling speed of 300 rpm, the rest is the same as in Example 1.

[0120] Comparative Example 3:

[0121] In this example, except for a sulfoaluminate cement clinker amount of 3 parts, the rest is the same as in Example 1.

[0122] Table 1, test results,

[0123] Example 3-day compressive strength (MPa) Alkaline matching index Flocculation structure dispersion index Synergistic enhancement index Example 1 35.6 0.95 0.88 0.89 Example 2 37.2 0.96 0.90 0.91 Example 3 32.8 0.93 0.85 0.86 Example 4 36.5 0.95 0.92 0.90 Example 5 36.0 0.95 0.89 0.89 Comparative Example 1 30.2 0.95 0.87 0.75 Comparative Example 2 28.5 0.94 0.79 0.71 Comparative Example 3 26.8 0.82 0.83 0.67

[0124] From the data in the table, it can be concluded that compared with Example 1, the basic matching index of Example 2 is slightly improved, but the compressive strength is significantly improved, which proves that within the range of the ratio, appropriately increasing the proportion of red mud and optimizing the structure of solid waste raw materials can more fully utilize the alkalinity of red mud and synergistically improve the cementitious performance. The indexes and compressive strength of Example 3 are the lowest among Examples 1, 2 and 3, indicating that too low red mud content leads to insufficient alkaline activation, and too high slag content cannot contribute to the optimal strength because its potential activity is not fully activated. After increasing the ball milling speed in Example 4, the flocculation structure dispersion index is significantly improved, which reflects that higher mechanical activation energy effectively breaks down the flocculation structure of the material, making it more uniform. After increasing the activation temperature in Example 5, the synergistic enhancement index remains at a high level of 0.89, and the compressive strength is basically the same as that of Example 1 and slightly higher, which shows that appropriately increasing the activation temperature helps to speed up and deepen the chemical activation process, which has a positive effect on maintaining and slightly improving the material performance. The synergistic enhancement index of Comparative Example 1 drops to 0.75 due to the complete absence of polymer emulsion, although its basic hydration reaction is acceptable, the toughness and density of the material system are severely insufficient, resulting in a significant decrease in compressive strength compared to all examples with polymer emulsion added, which shows that polymer emulsion is indispensable for bridging micro-cracks and improving the overall mechanical properties of the material. The flocculation structure dispersion index of Comparative Example 2 is only 0.79 due to the low ball milling speed, indicating that the composite activator does not effectively break down and disperse the flocculation structure of the initial mixture, and the material is not fully activated. This leads to a lower compressive strength, which proves the necessity of sufficient mechanical activation intensity for obtaining qualified material state and final performance. The basic matching index of Comparative Example 3 is only 0.82 due to the insufficient amount of sulphoaluminate cement clinker, which leads to the inability of red mud to be effectively "fired" and supplemented, and the inability to fully activate the potential hydration activity of slag and steel slag.

[0125] So far, the technical solutions of the present application have been described in conjunction with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will fall within the protection scope of the present application.

Claims

1. A method for preparing a steel slag composite cementitious material containing red mud, characterized by, The method comprises the following steps: mixing red mud, slag, steel slag, desulfurization gypsum and sulphoaluminate cement clinker under preset batching conditions to obtain an initial mixture; obtaining an X-ray diffraction pattern of the initial mixture, determining a basicity matching index based on the X-ray diffraction pattern, to determine whether the excitation ability of the basicity of the red mud to the potential hydration activity of the slag and the steel slag meets the standard, and adjusting the weight fraction of the sulphoaluminate cement clinker according to the ratio of the basicity matching index to a preset basicity matching index; adding a composite activator to the initial mixture with the excitation ability meeting the standard, and treating under preset activation conditions to obtain an activated slurry; obtaining a rheological curve of the activated slurry, determining a flocculation structure dispersion index based on the rheological curve, to determine whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified, and adjusting the ball milling speed according to a flocculation structure dispersion index difference between a preset flocculation structure dispersion index and the flocculation structure dispersion index; adding a polymer emulsion to the activated slurry with the dispersion effect qualified, and blending modification under preset stirring conditions to obtain an initial composite cementitious material; obtaining the compressive strength data of the initial composite cementitious material after curing, determining a synergistic enhancement index based on the compressive strength data, to determine whether the synergistic enhancement effect of the polymer emulsion and the activated slurry is qualified, and adjusting the dropping speed of the polymer emulsion according to a relative difference between a preset synergistic enhancement index and the synergistic enhancement index; under the condition that the synergistic enhancement effect is qualified, after drying and grinding, a red mud-containing steel slag composite cementitious material is obtained.

2. The method for preparing a red mud-containing steel slag composite cementitious material according to claim 1, characterized by, The determination of whether the excitation ability of the basicity of the red mud to the potential hydration activity of the slag and the steel slag meets the standard is based on the comparison result that the basicity matching index is less than or equal to the preset basicity matching index.

3. The method for preparing a red mud-containing steel slag composite cementitious material according to claim 2, characterized in that, The process of obtaining the basicity matching index comprises: extracting the red mud integral intensity of the sodalite characteristic peak in the red mud; extracting the steel slag integral intensity of the glass body hump of the slag and the steel slag; extracting the total integral intensity of the X-ray diffraction pattern within a preset range; the basicity matching index is the product of the red mud integral intensity and the steel slag integral intensity divided by the square of the total integral intensity.

4. The method for preparing a red mud-containing steel slag composite cementitious material according to claim 3, characterized in that, The process of adjusting the weight fraction of the aluminate cement clinker comprises: determining to increase the weight fraction of the sulphoaluminate cement clinker by a first preset weight fraction adjustment coefficient based on the comparison result that the ratio is less than or equal to a preset ratio; or, determining to increase the weight fraction of the sulphoaluminate cement clinker by a second preset weight fraction adjustment coefficient based on the comparison result that the ratio is greater than the preset ratio.

5. The method of claim 4, wherein the method further comprises the step of: The determination of whether the dispersion effect of the composite activator on the flocculation structure of the initial mixture is qualified is based on the comparison result that the flocculation structure dispersion index is less than or equal to a preset flocculation structure dispersion index, wherein ​ the flocculation structure dispersion index is determined according to the thixotropic loop area of the activated slurry thixotropic loop and a theoretical thixotropic loop area.

6. The method of claim 5, wherein the method further comprises the step of: The process of adjusting the ball milling speed comprises: ​ determining to increase the ball milling speed by a first preset speed adjustment coefficient based on the comparison result that the structure dispersion index difference is less than or equal to a preset difference; or, determining to increase the ball milling speed by a second preset speed adjustment coefficient based on the comparison result that the structure dispersion index difference is greater than the preset difference.

7. The method according to claim 6, wherein the method is characterized by, The substandard synergistic reinforcing effect of the polymer emulsion and the activated slurry is determined based on a comparison result that the synergistic reinforcing index is less than or equal to a preset synergistic reinforcing index, wherein, The synergistic reinforcing index is determined according to an average value of initial composite gel compressive strength and an average value of compressive strength of a silicate cement test block.

8. The method for preparing a red mud-containing steel slag composite cementitious material according to claim 7, characterized in that, The process of adjusting the dropping speed of the polymer emulsion comprises: determining to reduce the dropping speed by a first preset dropping speed adjustment coefficient based on a comparison result that the relative difference is less than or equal to a preset relative difference; or, determining to reduce the dropping speed by a second preset dropping speed adjustment coefficient based on a comparison result that the relative difference is greater than the preset relative difference.

9. The method of claim 8, wherein the method further comprises the step of: The composite activator is sodium sulfate and silica fume. ​ 10. A red mud-containing steel slag composite cementitious material prepared by the method of any one of claims 1 to 9, characterized in that, The composition comprises 15-25 parts of red mud, 35-45 parts of slag, 20-30 parts of steel slag, 6-9 parts of desulfurization gypsum, 5-8 parts of sulphoaluminate cement clinker, 1-5 parts of composite activator and 3-5 parts of polymer emulsion.

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