A process for the preparation of cementitious materials using sulphur-containing tailings

Abstract

The application discloses a process for preparing cement-based cementitious materials by using sulfur-containing tailings, which comprises the following steps: (1) preparing activated desulfurization tailings; (2) preparing solidified desulfurization tailings; and (3) preparing cement-based cementitious materials. The process effectively overcomes the compatibility problem between the sulfur-containing tailings and the concrete materials when the sulfur-containing tailings are used for preparing the concrete materials, and realizes good solidification of heavy metal elements in the sulfur-containing tailings, thereby helping to alleviate the pollution problem caused by the dissolution of the heavy metal elements from the concrete structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sulfur-containing tailings treatment, and particularly relates to a process for preparing cement-based cementitious materials by using sulfur-containing tailings. BACKGROUND

[0002] A large amount of tailings will be produced in the process of metal mineral exploitation and mineral processing, and the content of target metal elements in the tailings is very low, which does not have the value of extraction. Therefore, a large amount of tailings is accumulated as solid waste in the mining area, and only a small part is simply utilized, such as being used as roadbed material for landfill, being used in concrete to replace part of the aggregate, etc. The accumulated tailings not only occupy a large amount of land resources, but also cause soil and water pollution, which brings a great burden to enterprises.

[0003] Sulfur-containing tailings are tailings produced when associated sulfides (such as FeS2) are mined in metal mines (such as copper mines, gold mines, etc.). When the tailings are used as concrete raw materials, there is a problem of incompatibility, which can cause the mechanical properties of the concrete structure to decrease or even crack. This is because FeS2 in the sulfur-containing tailings is unstable in nature, and reacts with water molecules under the oxidation of oxygen to form sulfuric acid, which further reacts with calcium hydroxide, a cement hydration product in concrete, to form calcium sulfate. Calcium sulfate reacts with unhydrated cement clinker calcium aluminate to form expansive ettringite, which can easily cause cracks in the internal structure of the concrete, deteriorating the safety and durability of the concrete structure. In addition, after the consumption of calcium hydroxide, the alkalinity in the internal structure of the concrete will decrease, which will weaken the protection of the steel bars, making the steel bars more prone to rust. In addition, sulfur-containing tailings are also carriers of heavy metal elements, and the heavy metal elements contained therein not only cause environmental pollution, but also easily seep out under the action of rainwater when used as concrete raw materials, causing environmental pollution, especially when used in concrete materials for water conservancy projects. Therefore, the utilization of sulfur-containing tailings in concrete not only needs to consider the compatibility problem, but also needs to consider the pollution problem caused by heavy metal elements. SUMMARY

[0004] One of the technical problems solved by the present application is to overcome the compatibility problem between sulfur-containing tailings and concrete when used for preparing concrete materials, and to provide a process for preparing cement-based cementitious materials by using sulfur-containing tailings, which can achieve good solidification of heavy metal elements in the sulfur-containing tailings, and help to alleviate the pollution problem caused by the dissolution of heavy metal elements from the concrete structure.

[0005] The technical solution adopted in this invention is: a process for preparing cement-based cementitious materials using sulfur-containing tailings, comprising the following steps: S1, mixing sulfur-containing tailings, sodium carbonate solution and hydrogen peroxide solution to form a wet material, then placing the wet material in a sealed container and steam curing it under heating conditions to obtain activated desulfurized tailings; S2, mixing the activated desulfurized tailings with ordinary silicate cement powder and water to form a mortar, then naturally curing the mortar; S3, crushing the hardened body obtained in S2 into particles, then heat-treating it to obtain solidified desulfurized tailings; S4, mixing cement, fly ash, coarse aggregate, fine aggregate, water-reducing agent, fiber, mixing water and the solidified desulfurized tailings and stirring evenly to obtain cement-based cementitious materials.

[0006] As a further improvement of the present invention, in S1, the material-liquid ratio of sulfur-containing tailings, sodium carbonate solution, and hydrogen peroxide solution is 1g:4-6.5ml:1.3-1.8ml; the mass fraction of the sodium carbonate solution is 12-17%, and the mass fraction of the hydrogen peroxide solution is 1-3%.

[0007] As a further improvement of the present invention, in S2, the weight ratio of activated desulfurization tailings, ordinary silicate cement powder and water is 1.45-1.8:1.0:0.42-0.5.

[0008] As a further improvement of the present invention, in step S1, the heating temperature is 90–105°C, and the steam curing time is 1.5–2.5 hours. This allows the FeS2 in the sulfur-containing tailings to react fully, and the resulting sulfuric acid is neutralized by sodium carbonate, thus eliminating the problem of concrete performance degradation caused by FeS2.

[0009] As a further improvement of the present invention, in step S2, the natural curing time is 5 to 7 days, allowing the mortar to undergo a hydration reaction to form a hardened body.

[0010] As a further improvement of the present invention, in step S3, the hardened body is crushed into particles with a particle size of 20 to 50 mesh; the heat treatment temperature is 580 to 640°C, and the heating and holding time is 1 to 1.5 hours.

[0011] As a further improvement of the present invention, in S4, the weight ratio of cement, fly ash, coarse aggregate, fine aggregate, water-reducing agent, fiber, mixing water, and solidified desulfurization tailings is 100-115:18-25:270-315:100-140:1-2:4.5-8:62-71:30-45.

[0012] As a further improvement of the present invention, in step S4, the water-reducing agent is any one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, aminosulfonate water-reducing agent, or aliphatic water-reducing agent.

[0013] As a further improvement of the present invention, the fiber is at least one of carbon fiber, steel fiber, polypropylene fiber or polyacrylonitrile fiber; the length of the fiber is 10 to 20 mm.

[0014] The beneficial effects of this invention are as follows: Addressing the compatibility issues and heavy metal pollution problems associated with the application of sulfur-containing tailings in concrete, this invention first involves steam curing a wet material formed by mixing sulfur-containing tailings, sodium carbonate solution, and hydrogen peroxide solution under heating conditions. During this process, FeS2 in the sulfur-containing tailings undergoes an oxidation reaction under the action of water vapor and initial oxygen provided by the sodium carbonate solution, gradually decomposing FeS2 into ferric oxide and sulfuric acid. The sulfuric acid is neutralized by sodium carbonate to form sodium sulfate, thereby converting unstable sulfides in the tailings into stable sulfides. The resulting ferric oxide acts as a catalyst, promoting the decomposition of hydrogen peroxide solution and releasing oxygen for further oxidation and decomposition of the sulfur-containing tailings.

[0015] Meanwhile, both sodium carbonate and sodium sulfate can activate tailings with alkali, causing the silicon-oxygen bonds (Si-O) in silica and the aluminum-oxygen bonds (Al-O) in alumina in the tailings surface to break, thereby converting the inert surface of the tailings into an active surface. These broken chemical bonds can recombine in subsequent processes to form a three-dimensional network of cementitious products, which effectively solidifies the heavy metal elements in the tailings.

[0016] Furthermore, the process described above not only achieves desulfurization of sulfur-containing tailings, but also utilizes a composite activation method formed by two different activators, sodium carbonate and sodium sulfate, which is more conducive to activating the activity of the tailings surface layer. After the above process, not only are the unstable sulfides in the sulfur-containing tailings converted into stable substances, but the activity of the tailings is also released.

[0017] Simultaneously, this invention involves mixing the activated desulfurized tailings obtained through the above-mentioned process with ordinary silicate cement powder and water to form a mortar, which is then cured to form a hardened body. During this process, the calcium hydroxide produced by cement hydration reacts with the active surface layer of the tailings to form hydrated calcium silicate and hydrated calcium aluminate cementitious components, which can effectively solidify the heavy metal elements loaded on the tailings. This also allows the cement to more tightly coat the tailings surface, forming a coating layer. Because this coating layer is rich in cement hydration cementitious components, it helps to further prevent the leaching of heavy metal elements, forming a multi-layered solidification of metal ions. The calcium sulfate formed by sodium sulfate and the hydration product calcium hydroxide further reacts with the calcium aluminate in the cement to form micro-expansive hydrated calcium sulfoaluminate. This calcium sulfate, filling the coating layer, can provide shrinkage compensation during the hardening stage, compensating for the decrease in the density of the coating layer and reducing the weakening of its curing ability. The coating layer on the surface of the hardened particles obtained after the above treatment is in an inert state. Therefore, the hardened particles are heat-treated to dehydrate the hydrated calcium silicate and hydrated calcium aluminate in the coating layer, thereby converting the inert hydrated calcium silicate and calcium aluminate into components with certain hydration activity. When these hardened particles are used as concrete raw materials, they can undergo a hydration reaction again under the action of mixing water, so that the hardened particles are more tightly bonded to the concrete matrix and the strength of the concrete is improved. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments.

[0019] Example 1.

[0020] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0021] (1) Sulfur-containing tailings (FeS2 mass fraction of 9.61%, from a mining area in Tongling City, Anhui Province), 15% sodium carbonate solution, and 2% hydrogen peroxide solution were mixed in a ratio of 1g:5.5ml:1.6ml to form a wet material. The wet material was then placed in a sealed reaction vessel and heated to 100℃ and kept at that temperature for 2 hours for steam curing treatment. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0022] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.6 parts by weight: 1.0 parts by weight: 0.45 parts by weight and stirred evenly to form a mortar. The mortar is then naturally cured for 7 days. After completion, the hardened body is crushed and sieved to remove particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 600°C for 75 minutes. After completion, it is cooled to room temperature to obtain the solidified desulfurization tailings.

[0023] (3) Take the following raw materials: 110 parts by weight of 42.5 ordinary Portland cement, 23 parts by weight of fly ash, 300 parts by weight of coarse aggregate, 125 parts by weight of fine aggregate, 1.65 parts by weight of PCE-101 polycarboxylate superplasticizer, 7 parts by weight of fiber, 68 parts by weight of mixing water, and 40 parts by weight of the solidified desulfurized tailings prepared in this embodiment. Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5mm. The fiber is polypropylene fiber filament with a length of 15mm. Place the above-mentioned 42.5 ordinary Portland cement, fly ash, coarse aggregate, fine aggregate, fiber and solidified desulfurized tailings in a mixer and stir for 10min. Then add the superplasticizer and mixing water and continue stirring for 5min to obtain cement-based cementitious material.

[0024] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0025] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0026] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 67.21 MPa 0.004 0.082 0.047 0.413 0.036

[0027] Example 2.

[0028] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0029] (1) Sulfur-containing tailings (same as in Example 1 above), 12% sodium carbonate solution, and 1.5% hydrogen peroxide solution were mixed in a ratio of 1g:6.5ml:1.8ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 90°C, and kept at that temperature for 2 hours for steam curing treatment. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0030] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.45 parts by weight: 1.0 parts by weight: 0.42 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 5 days. After completion, the hardened body is crushed and sieved to separate particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 580°C for 90 minutes. After completion, it is cooled to room temperature to obtain the solidified desulfurization tailings.

[0031] (3) Take the following raw materials: 100 parts by weight of 42.5 ordinary Portland cement, 18 parts by weight of fly ash, 280 parts by weight of coarse aggregate, 100 parts by weight of fine aggregate, 1 part by weight of PCE-101 polycarboxylate superplasticizer, 5 parts by weight of fiber, 62 parts by weight of mixing water, and 30 parts by weight of the solidified desulfurized tailings prepared in this embodiment. Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5mm. The fiber is polyacrylonitrile fiber with a length of 10mm. Place the above-mentioned 42.5 ordinary Portland cement, fly ash, coarse aggregate, fine aggregate, fiber and solidified desulfurized tailings in a mixer and stir for 10min. Then add the superplasticizer and mixing water and continue stirring for 5min to obtain cement-based cementitious material.

[0032] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0033] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0034] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 63.54 MPa Not Detected 0.063 0.031 0.208 0.017

[0035] Example 3.

[0036] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0037] (1) Sulfur-containing tailings (same as in Example 1 above), 17% sodium carbonate solution, and 3% hydrogen peroxide solution were mixed in a ratio of 1g:4ml:1.3ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 90°C, and kept at that temperature for 2.5 hours for steam curing. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0038] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.5 parts by weight: 1.0 parts by weight: 0.48 parts by weight and stirred evenly to form a mortar. The mortar is then naturally cured for 6 days. After completion, the hardened body is crushed and sieved to remove particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 620°C for 70 minutes. After completion, it is cooled to room temperature to obtain the solidified desulfurization tailings.

[0039] (3) Take the following raw materials: 115 parts by weight of 42.5 ordinary silicate cement, 25 parts by weight of fly ash, 315 parts by weight of coarse aggregate, 140 parts by weight of fine aggregate, 2 parts by weight of ASP-QN aminosulfonate water-reducing agent, 8 parts by weight of fiber, 71 parts by weight of mixing water, and 45 parts by weight of the solidified desulfurized tailings prepared in this embodiment. Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15 mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5 mm. The fiber is carbon fiber with a length of 20 mm. Place the above-mentioned 42.5 ordinary silicate cement, fly ash, coarse aggregate, fine aggregate, fiber and solidified desulfurized tailings in a mixer and stir for 10 min. Then add the water-reducing agent and mixing water and continue stirring for 5 min to obtain cement-based cementitious material.

[0040] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0041] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0042] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 66.03 MPa Not Detected 0.032 0.056 0.482 0.041

[0043] Example 4.

[0044] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0045] (1) Sulfur-containing tailings (same as in Example 1 above), 15% sodium carbonate solution, and 1% hydrogen peroxide solution were mixed in a ratio of 1g:5ml:1.7ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 105°C, and kept at that temperature for 1.5 hours for steam curing. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0046] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.8 parts by weight: 1.0 parts by weight: 0.5 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 7 days. After completion, the hardened body is crushed and sieved to separate particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 640°C for 60 minutes for heat treatment. After completion, it is cooled to room temperature to obtain solidified desulfurization tailings.

[0047] (3) Take the following raw materials: 105 parts by weight of 42.5 ordinary Portland cement, 20 parts by weight of fly ash, 270 parts by weight of coarse aggregate, 120 parts by weight of fine aggregate, 1.5 parts by weight of ASP-QN aminosulfonate water-reducing agent, 4.5 parts by weight of fiber, 65 parts by weight of mixing water, and 35 parts by weight of the solidified desulfurized tailings prepared in this embodiment. Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5mm. The fiber is steel fiber with a length of 12mm. Place the above-mentioned 42.5 ordinary Portland cement, fly ash, coarse aggregate, fine aggregate, fiber and solidified desulfurized tailings in a mixer and stir for 10min. Then add the water-reducing agent and mixing water and continue stirring for 5min to obtain cement-based cementitious material.

[0048] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0049] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0050] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 64.72 MPa 0.001 0.075 0.039 0.322 0.013

[0051] Example 5.

[0052] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0053] (1) Take the following raw materials: 110 parts by weight of 42.5 ordinary Portland cement, 23 parts by weight of fly ash, 300 parts by weight of coarse aggregate, 125 parts by weight of fine aggregate, 1.65 parts by weight of PCE-101 polycarboxylate superplasticizer, 7 parts by weight of fiber, 68 parts by weight of mixing water, and 40 parts by weight of sulfur-containing tailings (FeS2 mass fraction of 9.61%, from a mining area in Tongling City, Anhui Province). Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15 mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5 mm. The fiber is polypropylene fiber filament with a length of 15 mm.

[0054] (2) Place the above-mentioned 42.5 ordinary silicate cement, fly ash, coarse aggregate, fine aggregate, fiber and sulfur-containing tailings in a mixer and stir for 10 minutes. Then add the water-reducing agent and mixing water and continue stirring for 5 minutes to obtain cement-based cementitious material.

[0055] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0056] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0057] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 32.18 MPa 4.36 15.29 107.15 48.32 0.83

[0058] Example 6

[0059] A process for preparing cement-based cementitious materials using sulfur-containing tailings differs from Example 1 above in that the solidified desulfurized tailings in this example are prepared using the following method:

[0060] (1) Sulfur-containing tailings (FeS2 mass fraction of 9.61%, from a mining area in Tongling City, Anhui Province), water, and 2% hydrogen peroxide solution were mixed in a ratio of 1g:5.5ml:1.6ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 100℃ and kept at that temperature for 2 hours for steam curing treatment. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0061] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.6 parts by weight: 1.0 parts by weight: 0.45 parts by weight and stirred evenly to form a mortar. The mortar is then naturally cured for 7 days. After completion, the hardened body is crushed and sieved to remove particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 600°C for 75 minutes. After completion, it is cooled to room temperature to obtain the solidified desulfurization tailings.

[0062] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0063] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0064] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 43.87 MPa 1.44 3.16 49.23 22.64 0.37

[0065] Example 7.

[0066] A process for preparing cement-based cementitious materials using sulfur-containing tailings differs from Example 2 above in that the solidified desulfurized tailings in this example are prepared using the following method:

[0067] (1) The sulfur-containing tailings (same as in Example 1 above) are mixed with a 12% sodium carbonate solution at a ratio of 1g:6.5ml to form a wet material. The wet material is then placed in a reaction vessel, sealed, heated to 90°C and kept at that temperature for 2 hours for steam curing treatment. After completion, it is cooled to room temperature to obtain activated desulfurized tailings.

[0068] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.45 parts by weight: 1.0 parts by weight: 0.42 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 5 days. After completion, the hardened body is crushed and sieved to separate particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 580°C for 90 minutes. After completion, it is cooled to room temperature to obtain the solidified desulfurization tailings.

[0069] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0070] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0071] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 39.42 MPa 2.07 5.51 26.9 19.76 0.22

[0072] Example 8

[0073] A process for preparing cement-based cementitious materials using sulfur-containing tailings differs from Example 4 above in that the solidified desulfurized tailings in this example are prepared using the following method:

[0074] (1) Sulfur-containing tailings (same as in Example 1 above), 15% sodium carbonate solution, and 1% hydrogen peroxide solution were mixed in a ratio of 1g:5ml:1.7ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, and left to stand at room temperature for 1.5 hours to obtain activated desulfurized tailings.

[0075] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.8 parts by weight: 1.0 parts by weight: 0.5 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 7 days. After completion, the hardened body is crushed and sieved to separate particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 640°C for 60 minutes for heat treatment. After completion, it is cooled to room temperature to obtain solidified desulfurization tailings.

[0076] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0077] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0078] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Zn) Cadmium (Cd) Test Value 45.08 MPa 1.12 2.33 17.48 16.67 0.15

[0079] Example 9.

[0080] A process for preparing cement-based cementitious materials using sulfur-containing tailings includes the following steps:

[0081] (1) Sulfur-containing tailings (same as in Example 1 above), 17% sodium carbonate solution, and 3% hydrogen peroxide solution were mixed in a ratio of 1g:4ml:1.3ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 90°C, and kept at that temperature for 2.5 hours for steam curing. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0082] (2) Take the following raw materials: 115 parts by weight of 42.5 ordinary Portland cement, 25 parts by weight of fly ash, 315 parts by weight of coarse aggregate, 140 parts by weight of fine aggregate, 2 parts by weight of ASP-QN aminosulfonate water-reducing agent, 8 parts by weight of fiber, 71 parts by weight of mixing water, and 45 parts by weight of the activated desulfurization tailings prepared in this embodiment. Wherein: the coarse aggregate is continuously graded crushed stone with a particle size of 5-15 mm. The fine aggregate is continuously graded river sand with a particle size of 0.2-0.5 mm. The fiber is carbon fiber with a length of 20 mm. Place the above-mentioned 42.5 ordinary Portland cement, fly ash, coarse aggregate, fine aggregate, fiber, and activated desulfurization tailings in a mixer and stir for 10 minutes. Then add the water-reducing agent and mixing water and continue stirring for 5 minutes to obtain the cement-based cementitious material.

[0083] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0084] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0085] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 48.26 MPa 1.85 7.04 30.13 10.94 0.28

[0086] Example 10.

[0087] A process for preparing cement-based cementitious materials using sulfur-containing tailings differs from Example 2 above in that the solidified desulfurized tailings in this example are prepared using the following method:

[0088] (1) Sulfur-containing tailings (same as in Example 1 above), 12% sodium carbonate solution, and 1.5% hydrogen peroxide solution were mixed in a ratio of 1g:6.5ml:1.8ml to form a wet material. The wet material was then placed in a reaction vessel, sealed, heated to 90°C, and kept at that temperature for 2 hours for steam curing treatment. After completion, it was cooled to room temperature to obtain activated desulfurized tailings.

[0089] (2) The activated desulfurization tailings are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.45 parts by weight: 1.0 parts by weight: 0.42 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 5 days. After completion, the hardened body is crushed and sieved to remove particles with a particle size between 20 and 50 mesh, thus obtaining the solidified desulfurization tailings.

[0090] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0091] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0092]

[0093]

[0094] Example 11

[0095] A process for preparing cement-based cementitious materials using sulfur-containing tailings differs from Example 4 above in that the solidified desulfurized tailings in this example are prepared using the following method: Sulfur-containing tailings (FeS2 mass fraction of 9.61%, from a mining area in Tongling City, Anhui Province) are mixed with 42.5 ordinary silicate cement powder and water in a ratio of 1.8 parts by weight: 1.0 parts by weight: 0.5 parts by weight, and stirred evenly to form a mortar. The mortar is then naturally cured for 7 days. After completion, the hardened body is crushed and sieved to separate particles with a particle size between 20 and 50 mesh. It is then placed in a heating furnace and heated to 640°C for 60 minutes for heat treatment. After completion, it is cooled to room temperature to obtain the solidified desulfurized tailings.

[0096] The cement-based binder material prepared in this embodiment was poured into a mold to form concrete specimens with dimensions of 100×100×100mm. These specimens were then cured for 28 days under standard curing conditions of 20±2℃ and 95% relative humidity. The compressive strength of the concrete specimens was then tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T 50081-2019), and the results are shown in the table below.

[0097] Concrete test blocks prepared from the cement-based binder of this embodiment were immersed in a container filled with deionized water. The container was then sealed with plastic wrap and placed on a HY-5 rotary shaker for 7 days. After completion, the concentration (mg / L) of heavy metal elements in the water was measured, and the results are shown in the table below.

[0098] Test Index Compressive Strength Arsenic (As) Lead (Pb) Zinc (Zn) Copper (Cu) Cadmium (Cd) Test Value 34.68 MPa 4.02 10.32 86.71 40.46 0.53

[0099] Those skilled in the art should understand that the protection scheme of the present invention is not limited to the above embodiments, and various arrangements, combinations and transformations can be made on the basis of the above embodiments. Without departing from the spirit of the present invention, all transformations made to the present invention fall within the protection scope of the present invention.

Claims

1. A process for preparing cement-based cementitious materials using sulfur-containing tailings, comprising the following steps: S1, sulfur-containing tailings, sodium carbonate solution and hydrogen peroxide solution are mixed to form a wet material, and then the wet material is placed in a sealed container and steamed under heating conditions to obtain activated desulfurized tailings. S2, mix the activated desulfurized tailings with ordinary silicate cement powder and water to form mortar, and then cure the mortar naturally. S3, the hardened body obtained in S2 is crushed into particles and then heat-treated to obtain solidified desulfurization tailings. S4. Cement, fly ash, coarse aggregate, fine aggregate, water-reducing agent, fiber, mixing water and the above-mentioned solidified desulfurization tailings are mixed and stirred evenly to obtain cement-based cementitious material.

2. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In step S1, the ratio of the sulfur-containing tailings, sodium carbonate solution, and hydrogen peroxide solution is 1g:4-6.5ml:1.3-1.8ml; the mass fraction of the sodium carbonate solution is 12-17%, and the mass fraction of the hydrogen peroxide solution is 1-3%.

3. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In S2, the weight ratio of activated desulfurization tailings, ordinary silicate cement powder, and water is 1.45-1.8:1.0:0.42-0.

5.

4. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In step S1, the heating temperature is 90–105°C, and the steam curing time is 1.5–2.5 hours.

5. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In S2, the natural curing time is 5 to 7 days.

6. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In step S3, the hardened body is crushed into particles with a particle size of 20-50 mesh; the heat treatment temperature is 580-640℃, and the heating and holding time is 1-1.5 hours.

7. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In S4, the weight ratio of cement, fly ash, coarse aggregate, fine aggregate, water-reducing agent, fiber, mixing water, and solidified desulfurization tailings is 100-115:18-25:270-315:100-140:1-2:4.5-8:62-71:30-45.

8. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: In step S4, the water-reducing agent is any one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, aminosulfonate water-reducing agent, or aliphatic water-reducing agent.

9. The process for preparing cement-based cementitious materials using sulfur-containing tailings according to claim 1, characterized in that: The fiber is at least one of carbon fiber, steel fiber, polypropylene fiber or polyacrylonitrile fiber; the length of the fiber is 10-20 mm.

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