A method for preparing admixtures using iron tailings

Abstract

This invention provides a method for preparing admixtures using iron tailings, relating to the field of admixture preparation technology. The method includes the following steps: (1) crushing the iron tailings and then ball milling them for the first time to obtain iron tailings powder, wherein the specific surface area of ​​the iron tailings powder is ≥325 m². 2 / kg; (2) Add an acidic modifier solution to the iron tailings powder and perform a second ball milling to obtain ultrafine powder, wherein the specific surface area of ​​the ultrafine powder is ≥900m². 2 / kg; (3) Add an active surface modifier and an active activator to the ultrafine powder, and perform a third ball milling to obtain the admixture. The prepared admixture has high activity and can directly replace part of the cement in situ to prepare concrete.

Description

Technical Field

[0001] This invention relates to the field of admixture preparation technology, and specifically to a method for preparing admixtures using iron tailings. Background Technology

[0002] With the booming development of China's steel industry, annual crude steel production reached 1.03 billion tons in 2021, accounting for more than 50% of global steel production capacity. Since steel companies primarily use iron ore as their raw material, iron ore tailings have become one of the largest sources of industrial solid waste in China. In recent years, Chinese mining and steel companies have generated over 2.55 billion tons of iron ore tailings annually, but the comprehensive utilization rate of these tailings is only 6.95%. As the grade of iron ore in China continues to decline, tailings production will further increase.

[0003] In traditional tailings treatment methods, tailings are mostly used for aggregate processing. However, due to the inherent physical and chemical properties of iron tailings, they are at a disadvantage compared to similar products in terms of strength, durability, and market acceptance. Furthermore, using iron tailings as an admixture in concrete preparation results in poor concrete strength due to the insufficient activity of the tailings. Therefore, how to utilize iron tailings to prepare highly active admixtures has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing admixtures using iron tailings, which solves the technical problem of low activity in admixtures prepared by existing methods for preparing admixtures using iron tailings.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing admixtures using iron tailings includes the following steps:

[0009] (1) Iron tailings are crushed and then subjected to a first ball milling process to obtain iron tailings powder, wherein the iron tailings powder has a specific surface area ≥325m². 2 / kg;

[0010] (2) An acidic modifier solution is added to the iron tailings powder, and a second ball milling is performed to obtain ultrafine powder with a specific surface area ≥900 m². 2 / kg;

[0011] (3) Add an active surface modifier and an active activator to the ultrafine powder and perform a third ball milling to obtain the admixture.

[0012] Preferably, the acid modifier solution is selected from at least one of phosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, tripolymetaphosphoric acid, tetrapolymetaphosphoric acid, formic acid, and nitric acid;

[0013] The acid modifier is added to the iron tailings powder by spraying.

[0014] The mass concentration of the acidic modifier solution is 10% to 16%.

[0015] The mass of the acid modifier is 1% to 3% of the mass of the iron tailings powder.

[0016] Preferably, the active surface modifier is selected from at least one of stearic acid, sodium dodecylbenzene sulfonate, and lignin sulfonate;

[0017] The mass of the active surface modifier is 0.1% to 0.5% of the mass of the iron tailings powder.

[0018] Preferably, the active activator comprises an inorganic base and an inorganic sulfate, wherein the mass ratio of the inorganic base to the inorganic sulfate is 1:3;

[0019] The mass of the active activator is 1% to 5% of the mass of the iron tailings powder.

[0020] Preferably, the inorganic base is selected from at least one of calcium hydroxide, sodium hydroxide, quicklime, and sodium carbonate.

[0021] Preferably, the sulfate is selected from at least one of calcium sulfate, sodium sulfate, aluminum sulfate, potassium sulfate, and gypsum. The gypsum is selected from at least one of titanium gypsum, phosphogypsum, citric acid gypsum, and desulfurized gypsum.

[0022] Preferably, the iron tailings have SiO2 ≥ 70% and CaO ≥ 2%.

[0023] Preferably, the ball milling speeds of the first ball mill, the second ball mill, and the third ball mill are all 200 r / min to 300 r / min.

[0024] Preferably, the grinding media of the first, second, and third ball mills are all zirconium oxide grinding balls, and the mass ratio of the iron tailings to the grinding media is 1:4 to 1:6.

[0025] Preferably, the grinding media is composed of zirconia grinding balls with a diameter of 0.4-0.6 mm, zirconia grinding balls with a diameter of 0.8-1.0 mm, and zirconia grinding balls with a diameter of 1.2-1.4 mm in a mass ratio of (2-4):(6-8):(4-6).

[0026] On the other hand, an admixture prepared by a method of preparing admixtures using iron tailings is used to replace cement in situ in the preparation of concrete, wherein the proportion of cement replacement is 10%-20%.

[0027] (III) Beneficial Effects

[0028] This invention provides a method for preparing admixtures using iron tailings. Compared with existing technologies, it has the following advantages:

[0029] The method of the present invention uses iron tailings as raw material and ball mills the iron tailings in the presence of acid modifier, active surface modifier and active activator to prepare admixture.

[0030] 1. The method of this invention includes ball milling iron tailings powder under the action of an acidic modifier, utilizing the synergistic effect of mechanical activation and chemical activation to improve the activity of the iron tailings. The acidic modifier can disrupt the surface microstructure of the iron tailings, making it easier to ball mill and thus improving the efficiency of mechanical activation.

[0031] 2. The method of the present invention includes cases where the specific surface area of ​​iron tailings is ≥900m². 2 When the surface modifier and activator are added at a concentration of / kg, the specific surface area of ​​the iron tailings is ≥900m². 2 Under the activation of / kg and active surface modifiers and activators, the dissolution rate of siliceous, calcareous, and aluminous groups in iron tailings is accelerated, increasing the activity index of iron tailings. As a result, the prepared admixture does not need to add other pozzolanic minerals to improve its activity, and can directly replace part of the cement in situ to prepare concrete. This allows for more efficient utilization of iron tailings as solid waste, reducing concrete costs and indirectly reducing carbon dioxide emissions. Moreover, the preparation method is simple and easy to apply in industrial production. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing admixtures using iron tailings, as detailed below:

[0035] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​325 m². 2 / kg;

[0036] Iron tailings powder was ground, and a 10% acidic modifier solution was added via spray during the ball milling process. The grinding continued until the specific surface area reached 900 m². 2 After adding / kg, add active surface modifier and active activator, and continue ball milling for 1 hour.

[0037] The acid modifier solution is selected from phosphoric acid solution with a mass concentration of 10%, and the mass of the acid modifier is 1% of the iron tailings powder; the active surface modifier is stearic acid, and its mass is 0.1% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 1% of the iron tailings powder.

[0038] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0039] Example 2

[0040] This embodiment provides a method for preparing admixtures using iron tailings, as detailed below:

[0041] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​330 m². 2 / kg;

[0042] Iron tailings powder was pulverized, and a 15% acidic modifier solution was added via spray during the ball milling process. The pulverization was continued until the specific surface area reached 900 m². 2 After adding / kg, add active surface modifier and active activator, and continue ball milling for 1 hour.

[0043] The acid modifier solution is selected from pyrophosphate with a mass concentration of 15%, and the mass of the acid modifier is 1% of the iron tailings powder; the active surface modifier is stearic acid, and its mass is 0.1% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 1% of the iron tailings powder.

[0044] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0045] Example 3

[0046] This embodiment provides a method for preparing admixtures using iron tailings, as detailed below:

[0047] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​335 m². 2 / kg;

[0048] Iron tailings powder was pulverized, and a 15% acidic modifier solution was added via spray during the ball milling process. The pulverization was continued until the specific surface area reached 900 m². 2 After adding / kg, add active surface modifier and active activator, and continue ball milling for 1 hour.

[0049] The acid modifier solution is selected from tripolyphosphoric acid with a mass concentration of 16%, and the mass of the acid modifier is 1% of the iron tailings powder; the active surface modifier is stearic acid, and its mass is 0.5% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 1% of the iron tailings powder.

[0050] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0051] Example 4

[0052] This embodiment provides a method for preparing admixtures using iron tailings, as detailed below:

[0053] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​350 m². 2 / kg;

[0054] Iron tailings powder was ground, and a 10% acidic modifier solution was added via spray during the ball milling process. The grinding continued until the specific surface area reached 900 m². 2 After adding / kg, add active surface modifier and active activator, and continue ball milling for 1 hour.

[0055] The acid modifier solution is tripolyphosphoric acid with a mass concentration of 16%, and the mass of the acid modifier is 1% of the iron tailings powder; the active surface modifier is stearic acid, and its mass is 1% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 5% of the iron tailings powder.

[0056] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0057] Comparative Example 1

[0058] Preparation of admixtures:

[0059] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​330 m². 2 / kg;

[0060] Iron tailings powder was pulverized without the addition of acidic modifier solution, surface modifier, or activator, and the iron tailings were directly ball-milled to a specific surface area of ​​900 m². 2 / kg.

[0061] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0062] Comparative Example 2

[0063] Preparation of admixtures:

[0064] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​330 m². 2 / kg;

[0065] During the second ball milling process, a 10% (w / w) acidic modifier solution was added via spray. The ball milling continued until the iron tailings powder had a specific surface area of ​​900 m². 2 / kg; then add the active surface modifier and ball mill for 1 hour.

[0066] The acid modifier solution is pyrophosphate with a mass concentration of 15%, and the mass of the acid modifier is 1% of the iron tailings powder; the active surface modifier is stearic acid, and its mass is 0.1% of the iron tailings powder.

[0067] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0068] Comparative Example 3

[0069] Preparation of admixtures:

[0070] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​330 m². 2 / kg;

[0071] During the second ball milling process, an acidic modifier with a mass concentration of 10% was added via spray, and the mixture was milled until the specific surface area reached 900 m². 2 Add the active activator after the volume is reduced to 1 kg, and continue ball milling for 1 hour.

[0072] The acid modifier solution is pyrophosphate with a mass concentration of 15%, and the mass of the acid modifier added is 1% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 1% of the iron tailings powder.

[0073] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0074] Comparative Example 4

[0075] Preparation of admixtures:

[0076] Iron tailings are crushed and then ball-milled to obtain iron tailings powder with a specific surface area of ​​330 m². 2 / kg;

[0077] Iron tailings powder was ground to a specific surface area of ​​900 m². 2 Add the active surface modifier and active activator after the weight is / kg, and continue ball milling for 1 hour.

[0078] The active surface modifier is stearic acid, which accounts for 0.5% of the iron tailings powder; the active activator is composed of calcium hydroxide and calcium sulfate in a mass ratio of 1:3, and the mass of the active activator is 1% of the iron tailings powder.

[0079] The grinding media of the ball mill consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to the grinding media is 1:4. The rotation speed of the ball mill is 250 r / min.

[0080] Comparative Example 5

[0081] Iron tailings were ground to a specific surface area of ​​325 m². 2 / kg, without the addition of acidic modifier solution, surface modifier, and activity activator. The ball milling media consists of zirconia grinding balls with a diameter of 0.4-0.6 mm, zirconia grinding balls with a diameter of 0.8-1.0 mm, and zirconia grinding balls with a diameter of 1.2-1.4 mm in a mass ratio of 2:6:4. The mass ratio of steel slag powder to ball milling media is 1:4, and the ball milling speed is 250 r / min.

[0082] Experimental Example

[0083] Experimental Sample Preparation:

[0084] 1. Prepare concrete samples according to the formula in Table 1.

[0085] 2. Referring to the formulations in Table 1, concrete samples were prepared by taking 10%, 20%, and 30% of the cement in the admixtures prepared in Examples 1-4 and Comparative Examples 1-5, respectively.

[0086] The 28-day compressive strength of concrete samples was determined according to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The results are shown in Table 2. In addition, the 28-day compressive strength of concrete samples prepared according to the formula in Table 1 is 34 MPa.

[0087] Table 1 Concrete Formula

[0088]

[0089] Table 2 Compressive strength of concrete specimens

[0090]

[0091] As shown in Examples 1-4, compared to the 28-day compressive strength of concrete samples prepared without cement replacement using admixtures, the 28-day compressive strength of concrete samples prepared by in-situ replacement of part of the cement with the admixtures prepared in this application first increases and then decreases with the increase of the proportion of cement replaced by admixtures. When the replacement ratio is between 10% and 20%, the 28-day compressive strength of the samples exceeds that of samples prepared with pure cement. This is because, on the one hand, the method of this invention ball mills the iron tailings powder under the action of an acidic modifier, and the synergistic effect of mechanical activation and chemical activation improves the activity of the iron tailings. On the other hand, when the specific surface area of ​​the iron tailings is ≥900 m², 2At a rate of / kg, under the activation of active surface modifiers and active activators, the dissolution rate of siliceous, calcareous, and aluminous groups in iron tailings is accelerated, thereby increasing the activity index of iron tailings. The resulting admixture can not only directly replace part of the cement in situ to prepare concrete, but also increase the strength of the prepared concrete within a certain replacement ratio range.

[0092] As can be seen from Comparative Examples 2-4, the 28-day compressive strength of concrete samples prepared by in-situ replacement of cement with the admixtures lacking any one of the components of acid modifier solution, surface modifier, and activator is lower than that of Example 2. Therefore, the synergistic effect among acid modifier solution, surface modifier, and activator improves the activity of the admixture.

[0093] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing admixtures using iron tailings, characterized in that, Includes the following steps: (1) Iron tailings are crushed and then ball-milled to obtain iron tailings powder, wherein the iron tailings powder has a specific surface area ≥ 325 m². 2 / kg; (2) An acidic modifier solution is added to the iron tailings powder, and a second ball milling is performed to obtain ultrafine powder with a specific surface area ≥900m². 2 / kg; (3) Add an active surface modifier and an active activator to the ultrafine powder and perform a third ball milling to obtain the admixture; The active activator comprises an inorganic base and an inorganic sulfate, wherein the mass ratio of the inorganic base to the inorganic sulfate is 1:3; The inorganic base is selected from at least one of calcium hydroxide, sodium hydroxide, quicklime, and sodium carbonate; The acid modifier solution is selected from at least one of phosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, tripolymethic acid, and tetrapolymethic acid. The mass concentration of the acid modifier solution is 10% to 16%; The mass of the acid modifier is 1% to 3% of the mass of the iron tailings powder; The active surface modifier is selected from stearic acid; The mass of the active surface modifier is 0.1% to 0.5% of the mass of the iron tailings powder; The mass of the active activator is 1% to 5% of the mass of the iron tailings powder.

2. The method for preparing admixtures using iron tailings as described in claim 1, characterized in that, The acidic modifier solution is added to the iron tailings powder by spraying.

3. The method for preparing admixtures using iron tailings as described in claim 1, characterized in that, The sulfate is selected from at least one of calcium sulfate, sodium sulfate, aluminum sulfate, potassium sulfate, and gypsum.

4. The method for preparing admixtures using iron tailings as described in claim 1, characterized in that, The iron tailings have SiO2 ≥ 70% and CaO ≥ 2%.

5. The method for preparing admixtures using iron tailings as described in claim 1, characterized in that, The ball milling speeds for the first, second, and third ball milling processes were all between 200 r / min and 300 r / min.

6. The method for preparing admixtures using iron tailings as described in claim 1, characterized in that, The grinding media for the first, second, and third ball milling processes are all zirconium oxide grinding balls, and the mass ratio of iron tailings to grinding media is 1:4 to 1:

6. The grinding media consists of zirconia grinding balls with a diameter of 0.4–0.6 mm, zirconia grinding balls with a diameter of 0.8–1.0 mm, and zirconia grinding balls with a diameter of 1.2–1.4 mm in a mass ratio of (2–4):(6–8):(4–6).

7. An admixture prepared by the method according to any one of claims 1-6, characterized in that, Concrete is prepared by replacing cement in situ with the aforementioned admixture, wherein the cement replacement ratio is 10%-20%.

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