Preparation method of high-activity iron tailing-based composite cementing material

Abstract

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of a high-activity iron tailing-based composite cementing material. Aiming at the problem of insufficient activity caused by low calcium and aluminum content and high magnesium content of low-silicon iron tailings (SiO2 is 15.3%-30%), mineral powder is taken as a mineral admixture, sepiolite nanofiber, carbonic anhydrase and nano cerium oxide are taken as a composite activator, 1-ethyl-3-methylimidazolium chloride is taken as a grinding aid, and a mechanical grinding process is combined, so that the gelling activity of the iron tailings is remarkably improved. The method comprises the following steps: 1) crushing and screening iron tailings; 2) mechanical-chemical grinding activation; and 3) preparing the composite cementing material. The chemical component defects of the iron tailings are compensated through the high-calcium and medium-aluminum characteristics of the mineral powder, the sepiolite nanofiber provides a fiber reinforcement effect and an active silicon magnesium source, carbonic anhydrase catalyzes CO2 conversion to promote carbonate solidification, nano cerium oxide regulates the hydration process and stabilizes magnesium ions, a C-S-H / N-A-S-H double-gel system is formed, and the high-calcium and medium-aluminum double-gel system is formed. The 28d compressive strength is improved by 40% or above compared with that of an unactivated system, the solid waste utilization rate reaches 30%, and MgO expansion is effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a method for preparing a highly active iron tailings-based composite cementitious material. Background Technology

[0002] Iron ore tailings (IOT) are solid waste generated during the iron ore beneficiation process. The amount of IOT produced is enormous; in my country, producing 1 ton of refined iron ore generates 2.5 to 3 tons of IOT, making it one of the highest-producing solid wastes in the country. Statistics show that my country's annual IOT production has reached 520 million tons, accounting for nearly half of the total tailings volume. IOT not only wastes a large amount of land, but tailings ponds also pose a risk of dam failure and leakage. IOT often accumulates for decades, and the large amounts of heavy metals it contains can pollute surrounding water bodies, soil, and living organisms through water flow and dust.

[0003] Cement-based materials are considered ideal carriers for disposing of iron tailings, but significant technical bottlenecks exist. Traditional research focuses on high-silica iron tailings (SiO2 > 60%), whose pozzolanic activity is high and can undergo a secondary reaction with cement hydration product Ca(OH)2 to form CSH gel. However, iron tailings generally have low cementitious activity, and not all types are easily utilized. In particular, low-silica, high-magnesium, and low-calcium-aluminum iron tailings face severe challenges in resource utilization. On the one hand, their low silicon, aluminum, and calcium content makes it difficult to provide sufficient amounts of active SiO2 and Al2O3 to participate in the hydration reaction, failing to effectively generate hydration products that support strength. On the other hand, the high MgO content may lead to slow hydration reactions in the later stages, accompanied by significant volume expansion, causing cracking and collapse of cement-based products, seriously jeopardizing their long-term durability and volume stability.

[0004] Currently, activation methods for this type of inert solid waste mainly focus on two categories: mechanical grinding to increase specific surface area and chemical activators to disrupt the vitreous structure. Traditional mechanical activation is extremely energy-intensive and offers limited compensation for chemical component defects; while conventional alkaline activators, although capable of activating aluminosilicates, are not only ineffective in addressing the expansion risk posed by high magnesium content but may even exacerbate the hazards. Existing technologies lack solutions that can simultaneously address the two core issues of "chemical component imbalance" and "magnesium ion hazards," resulting in poor activation effects and hindering large-scale utilization.

[0005] Therefore, developing an efficient composite activation method for iron tailings with low silicon, high magnesium, and low calcium aluminum content can significantly improve their gelling activity while effectively inhibiting their potential expansion. This has significant practical and economic value for promoting the large-scale resource utilization of iron tailings and reducing carbon emissions from the cement industry. Summary of the Invention

[0006] To address the aforementioned technical problems in the existing technology, this invention provides a method for preparing a highly active iron tailings-based composite cementitious material. The technical solution is as follows:

[0007] A method for activating iron tailings powder includes the following steps:

[0008] S11 crushes and screens iron tailings to obtain iron tailings powder with a particle size of 0.01-0.3mm.

[0009] S12 Take an appropriate amount of iron tailings powder, add the appropriate proportion of grinding aid, sepiolite nanofiber and mineral powder to the iron tailings powder, mix evenly and grind for 30 to 120 minutes.

[0010] S13 adds a composite activator to the pulverized composite powder obtained in S12, and after stirring evenly, a composite cementitious material is obtained.

[0011] The main mineral phases of the iron tailings in step S11 are halogen ore, quartz, calcite, amphibole, phlogopite, and pyrite, etc., and the main chemical components are: SiO2 25.00-39.52%, Fe2O3 6.36-12.32%, CaO 8.06-9.09%, Al2O3 2.60-6.01%, MgO 8.70-17.32%, TiO2 0.37-0.43%, Na2O 0.56-1.00%, SO3 3.90-5.05%, K2O 1.57-2.06%.

[0012] In step S12, the appropriate amount of iron tailings powder is 3-5 kg ​​of iron tailings powder.

[0013] In step S12, the grinding aid is selected from 1-ethyl-3-methylimidazolium chloride and other 1-ethyl-3-methylimidazolium compounds. After activation, the mass ratio of iron tailings powder to grinding aid is 1250 to 5000:1.

[0014] In step S12, the grinding aid is added in the following way: the appropriate proportion of grinding aid is added to the iron tailings powder, mixed evenly, and then water is added and stirred until the grinding aid is fully dissolved. The fully dissolved iron tailings powder is then placed in a 90°C drying oven and dried for 24 hours.

[0015] In step S12, a certain proportion of the mineral powder is 5%-15% of the total amount of cementitious materials.

[0016] The mineral powder used in step S12 is S95 mineral powder, whose main chemical composition is 35%–45% CaO and 2% SiO2.

[0017] 30%~38%, Al2O310%~18%, MgO 5%~15%, TFe 0.5%~2%, SO31%~2%, MnO 0.2%~2%, TiO20.5%~1.5%.

[0018] In step S12, a certain proportion of sepiolite nanofibers is 1.0% to 3.0% of the total mass of iron tailings. Sepiolite nanofibers can also be replaced by other fibrous magnesium silicate subtypes.

[0019] In step S13, the composite activator includes a certain proportion of nano-cerium oxide, which is 0.01% to 0.05% of the total mass of the cementitious material. The nano-cerium oxide needs to be ultrasonically dispersed for 5 to 10 minutes using an ultrasonic cell disruptor with a power of not less than 500W to form a stable suspension.

[0020] In step S13, the carbonic anhydrase accounts for 0.002% to 0.01% of the total mass of the gelling material, and it can also be replaced by other carbon dioxide fixation catalysts.

[0021] In step S13, the amount of iron tailings powder in the composite powder accounts for 15-30% of the total amount of composite cementitious material.

[0022] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0023] The above-mentioned scheme, by introducing S95 mineral powder as an admixture, effectively compensates for the key deficiency of the cementitious activity inherent in low-silica iron tailings. Low-silica iron tailings have low calcium and aluminum content but high magnesium content, making it difficult to form sufficient hydration products. The mineral powder, with its high calcium and moderate aluminum content, precisely supplements the key components lacking in iron tailings. The active components in the mineral powder react with the silica and alumina released after activation in the iron tailings, jointly constructing a CSH (calcium silicate hydrate) and NASH (sodium aluminum silicate) dual-gel system. Simultaneously, sepiolite nanofibers provide fiber reinforcement and an active source of silica and magnesium; carbonic anhydrase catalyzes CO2 conversion to promote carbonate solidification; and nano-cerium oxide regulates the hydration process and stabilizes magnesium ions, generating stable compounds that effectively inhibit potential later-stage expansion caused by MgO, ensuring the volume stability of the composite material.

[0024] The above-mentioned scheme achieves efficient resource utilization of low-silicon iron tailings, a major solid waste. The iron tailings content in the final composite cementitious material reaches 15%–30%, and the overall solid waste utilization rate reaches 30%, significantly reducing the land occupation and environmental risks associated with tailings storage. Simultaneously, the activated iron tailings powder can effectively replace a portion of cement, reducing reliance on traditional high-energy-consuming and high-carbon-emission cement, lowering production costs, and contributing to carbon emission reduction targets.

[0025] The above scheme reduces the agglomeration of iron tailings powder during the grinding process by adding grinding aids during the preparation of activated iron tailings powder, thereby increasing the specific surface area of ​​the iron tailings powder. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart involving a method for preparing a highly active iron tailings-based composite cementitious material according to an embodiment of the present invention; Detailed Implementation

[0028] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0029] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0030] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0031] This invention provides a method for preparing a highly active iron tailings-based composite cementitious material.

[0032] A method for activating iron tailings powder includes the following steps:

[0033] S11 crushes and screens iron tailings to obtain iron tailings powder with a particle size of 0.01-0.3mm.

[0034] S12 Take an appropriate amount of iron tailings powder, add the appropriate proportion of grinding aid, sepiolite nanofiber and mineral powder to the iron tailings powder, mix evenly and grind for 30 to 120 minutes.

[0035] S13 adds a composite activator to the pulverized composite powder obtained in S12, and after stirring evenly, a composite cementitious material is obtained.

[0036] The main mineral phases of the iron tailings in step S11 are halogen ore, quartz, calcite, amphibole, phlogopite, and pyrite, etc., and the main chemical components are: SiO2 25.00-39.52%, Fe2O3 6.36-12.32%, CaO 8.06-9.09%, Al2O3 2.60-6.01%, MgO 8.70-17.32%, TiO2 0.37-0.43%, Na2O 0.56-1.00%, SO3 3.90-5.05%, K2O 1.57-2.06%.

[0037] In step S12, the appropriate amount of iron tailings powder is 3-5 kg ​​of iron tailings powder.

[0038] In step S12, the grinding aid is selected from 1-ethyl-3-methylimidazolium chloride and other 1-ethyl-3-methylimidazolium compounds. After activation, the mass ratio of iron tailings powder to grinding aid is 1250 to 5000:1.

[0039] In step S12, the grinding aid is added in the following way: the appropriate proportion of grinding aid is added to the iron tailings powder, mixed evenly, and then water is added and stirred until the grinding aid is fully dissolved. The fully dissolved iron tailings powder is then placed in a 90°C drying oven and dried for 24 hours.

[0040] In step S12, a certain proportion of the mineral powder is 5%-15% of the total amount of cementitious materials.

[0041] The mineral powder used in step S12 is S95 mineral powder, whose main chemical composition is 35%–45% CaO and 2% SiO2.

[0042] 30%~38%, Al2O310%~18%, MgO 5%~15%, TFe 0.5%~2%, SO31%~2%, MnO 0.2%~2%, TiO20.5%~1.5%.

[0043] In step S12, a certain proportion of sepiolite nanofibers is 1.0% to 3.0% of the total mass of iron tailings. Sepiolite nanofibers can also be replaced by other fibrous magnesium silicate subtypes.

[0044] In step S13, the composite activator includes a certain proportion of nano-cerium oxide, which is 0.01% to 0.05% of the total mass of the cementitious material. The nano-cerium oxide needs to be ultrasonically dispersed for 5 to 10 minutes using an ultrasonic cell disruptor with a power of not less than 500W to form a stable suspension.

[0045] In step S13, the carbonic anhydrase accounts for 0.002% to 0.01% of the total mass of the gelling material, and it can also be replaced by other carbon dioxide fixation catalysts.

[0046] In step S13, the amount of iron tailings powder in the composite powder accounts for 15-30% of the total amount of composite cementitious material.

[0047] The following description, in conjunction with specific embodiments, illustrates this point.

[0048] Example 1

[0049] 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm was dried in a 90℃ forced-air drying oven to constant weight to obtain dried iron tailings powder. 3 kg of the above iron tailings powder was weighed, and 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride was added. Water was added and stirred until completely dissolved. The mixture was dried at 90℃ for 24 h to obtain pretreated iron tailings powder. 0.6 kg of S95 mineral powder and 60 g of sepiolite nanofibers were added, and the mixture was ground in an SM-500 cement test mill for 60 min to obtain a specific surface area ≥450 m². 2 / kg of activated composite powder.

[0050] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned activated composite powder, 1350g of standard sand and 225g of water evenly.

[0051] The mechanical strength of the mortar prepared in Example 1 was tested, and the specific test results are shown in Tables 1 and 2.

[0052] Example 2

[0053] 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm was dried in a 90℃ forced-air drying oven to constant weight to obtain dried iron tailings powder. 1.8 kg of the above iron tailings powder was weighed, and 0.63 g of grinding aid 1-ethyl-3-methylimidazolium chloride was added. Water was added and stirred until completely dissolved. The mixture was dried at 90℃ for 24 h to obtain pretreated iron tailings powder. 1.2 kg of S95 mineral powder and 60 g of sepiolite nanofibers were added, and the mixture was ground in an SM-500 cement test mill for 60 min to obtain a specific surface area ≥450 m². 2 / kg of activated composite powder.

[0054] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned activated composite powder, 1350g of standard sand and 225g of water evenly.

[0055] The mechanical strength of the mortar prepared in Example 2 was tested, and the specific test results are shown in Tables 1 and 2.

[0056] Example 3

[0057] 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm was dried in a 90℃ forced-air drying oven to constant weight to obtain dried iron tailings powder. 1.5 kg of the above iron tailings powder was weighed, and 0.525 g of grinding aid 1-ethyl-3-methylimidazolium chloride was added. Water was added and stirred until completely dissolved. The mixture was dried at 90℃ for 24 h to obtain pretreated iron tailings powder. 1.5 kg of S95 mineral powder and 60 g of sepiolite nanofibers were added, and the mixture was ground in an SM-500 cement test mill for 60 min to obtain a specific surface area ≥450 m². 2 / kg of activated composite powder.

[0058] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned activated composite powder, 1350g of standard sand and 225g of water evenly.

[0059] The strength of the mortar prepared in Example 3 was tested, and the specific test results are shown in Tables 1 and 2.

[0060] Comparative Example 1

[0061] Take 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm and dry it in a 90℃ forced-air drying oven until constant weight to obtain dried iron tailings powder. Weigh 3 kg of the above iron tailings powder, add 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride, add water and stir until completely dissolved; dry the mixed solution at 90℃ for 24 h to obtain pretreated iron tailings powder; add 60 g of sepiolite nanofibers, and grind in an SM-500 cement test mill for 30 min to obtain a specific surface area ≥450 m². 2 / kg of composite activated powder.

[0062] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned composite activated powder, 1350g of standard sand and 225g of water evenly.

[0063] The mechanical strength of the mortar prepared in Comparative Example 1 was tested, and the specific test results are shown in Tables 1 and 2.

[0064] Comparative Example 2

[0065] Take 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm and dry it in a 90℃ forced-air drying oven until constant weight to obtain dried iron tailings powder. Weigh 3 kg of the above iron tailings powder, add 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride, add water and stir until completely dissolved; dry the mixed solution at 90℃ for 24 h to obtain pretreated iron tailings powder; add 60 g of sepiolite nanofibers, and grind in an SM-500 cement test mill for 60 min to obtain a specific surface area ≥450 m². 2 / kg of composite activated powder.

[0066] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned composite activated powder, 1350g of standard sand and 225g of water evenly.

[0067] The mechanical strength of the mortar prepared in Comparative Example 2 was tested, and the specific test results are shown in Tables 1 and 2.

[0068] Comparative Example 3

[0069] 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm was dried in a 90℃ forced-air drying oven to constant weight to obtain dried iron tailings powder. 3 kg of the above iron tailings powder was weighed, and 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride was added. Water was added and stirred until completely dissolved. The mixture was dried at 90℃ for 24 h to obtain pretreated iron tailings powder. 60 g of sepiolite nanofibers were added, and the mixture was ground in an SM-500 cement test mill for 90 min to obtain a specific surface area ≥450 m². 2 / kg of composite activated powder.

[0070] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned composite activated powder, 1350g of standard sand and 225g of water evenly.

[0071] The mechanical strength of the mortar prepared in Comparative Example 3 was tested, and the specific test results are shown in Tables 1 and 2.

[0072] Comparative Example 4

[0073] Take 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm and dry them in a 90℃ forced-air drying oven until constant weight to obtain dried iron tailings powder. Weigh 3 kg of the above iron tailings powder, add 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride, add water and stir until completely dissolved; dry the mixed solution at 90℃ for 24 h to obtain pretreated iron tailings powder; add 60 g of sepiolite nanofibers, and grind in an SM-500 cement test mill for 120 min to obtain a specific surface area ≥450 m². 2 / kg of composite activated powder.

[0074] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned composite activated powder, 1350g of standard sand and 225g of water evenly.

[0075] The mechanical strength of the mortar prepared in Comparative Example 4 was tested, and the specific test results are shown in Tables 1 and 2.

[0076] Comparative Example 5

[0077] Take 4 kg of low-silica iron tailings with a particle size of 0.01–0.3 mm and dry them in a 90℃ forced-air drying oven until constant weight to obtain dried iron tailings powder. Weigh 3 kg of the above iron tailings powder, add 1.05 g of grinding aid 1-ethyl-3-methylimidazolium chloride, add water and stir until completely dissolved; dry the mixed solution at 90℃ for 24 h to obtain pretreated iron tailings powder.

[0078] The mortar was prepared by mixing a suspension containing 0.135g of nano-cerium oxide, a solution containing 0.0225g of carbonic anhydrase, 315g of P·O42.5 ordinary silicate cement, 135g of the above-mentioned pretreated iron tailings powder, 9g of sepiolite nanofibers, 1350g of standard sand and 225g of water evenly.

[0079] The mechanical strength of the mortar prepared in Comparative Example 5 was tested, and the specific test results are shown in Tables 1 and 2.

[0080] Performance Testing and Analysis

[0081] The mortars prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests in accordance with the requirements of the "Test Method for Strength of Cement Mortar (ISO)" (GB / T 17671-2021).

[0082] Table 1 shows the compressive strength test results of Examples 1-3 and Comparative Examples 1-5.

[0083]

[0084] Table 2 shows the flexural strength test results of Examples 1-3 and Comparative Examples 1-5.

[0085]

[0086] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-activity iron tailings-based composite cementitious material, comprising the following steps: S11. crushing and screening the iron tailings to obtain iron tailings powder having a particle size of 0.01-0.3 mm; S12. taking the iron tailings powder, adding grinding aids accounting for 0.02%-0.08% of the mass of the iron tailings powder, fibrous magnesium silicates accounting for 1.0%-3.0% of the mass of the iron tailings powder, and mineral powder accounting for 5%-15% of the total mass of the cementitious material, uniformly mixing, and grinding for 30-120 min; S13. adding a composite activator to the composite powder obtained in S12, the composite activator comprising nanometer cerium oxide accounting for 0.01%-0.05% of the total mass of the cementitious material and carbonic anhydrase accounting for 0.002%-0.01% of the total mass of the cementitious material, uniformly stirring, and obtaining a composite cementitious material; wherein the iron tailings powder in the composite powder accounts for 15%-30% of the total mass of the composite cementitious material.

2. The process for the preparation of high reactive iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S11, the mineral phases of the iron tailings are red amphibole, quartz, calcite, hornblende, phlogopite, and pyrite, and the chemical composition and content are SiO2 25.00-39.52%, Fe2O3 6.36-12.32%, CaO 8.06-9.09%, Al2O3 2.60-6.01%, MgO 8.70-17.32%, TiO2 0.37-0.43%, Na2O 0.56-1.00%, SO3 3.90-5.05%, and K2O 1.57-2.06%.

3. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S12, the grinding aids are 1-ethyl-3-methyl imidazole compounds, and the mass ratio of the activated iron tailings powder to the grinding aids is 1250-5000:

1.

4. The method of claim 3, wherein, The 1-ethyl-3-methyl imidazole compounds are 1-ethyl-3-methyl imidazole chloride.

5. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S12, the grinding aids are added to the iron tailings powder, uniformly mixed, water is added and stirred until the grinding aids are fully dissolved, and the iron tailings powder after full dissolution is placed in a 90°C drying oven for drying for 24 h.

6. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S12, the addition amount of the mineral powder is 5%-15% of the total amount of the cementitious material, and the mineral powder is S95 mineral powder, and the chemical composition and content are CaO 35%-45%, SiO2 30%-38%, Al2O3 10%-18%, MgO 5%-15%, TFe 0.5%-2%, SO3 1%-2%, MnO 0.2%-2%, and TiO2 0.5%-1.5%.

7. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S12, the addition amount of the fibrous magnesium silicates is 1.0-3.0% of the total mass of the iron tailings.

8. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1 wherein, In the step S12, the fibrous magnesium silicates are sepiolite nanofibers.

9. The process for the preparation of high reactivity iron ore tailings based composite cementitious material as claimed in claim 1, wherein, In the step S13, the nanometer cerium oxide needs to be ultrasonically dispersed for 5-10 min at a power of not less than 500 W by using an ultrasonic cell crusher to form a suspension.

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