Gelling base material for mine filling and capable of improving mixing amount of mineral separation tailings and filling material of cementing base material

Abstract

The invention discloses a gelling base material for mine filling. The gelling base material is modified non-ferrous metal smelting slag powder. The preparation method of the gelling base material comprises the steps of primary ball milling and secondary ball milling. The invention also discloses a filling material, which comprises the following components in percentage by weight: 90-95% of beneficiation tailings and 5-10% of modified non-ferrous metal smelting slag powder. According to the gelling base material for mine filling, under the optimized proportion, the gelling base material has the triple functions of efficient excitation, firm cementation and heavy metal stabilization on beneficiation tailings, the high utilization rate of the doping amount of the beneficiation tailings can reach 90% or above with the low doping amount, and environmental geological disasters caused by accumulation of a beneficiation tailings warehouse are effectively solved; the filling material has excellent working performance of high expansion degree and low bleeding rate, the early and long-term high compressive strength of the filling material is guaranteed, and meanwhile, the environmental safety of the filling material is also realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial waste resource utilization technology, specifically relating to a cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing and its backfilling material. Background Technology

[0002] Mineral processing tailings are solid wastes remaining after mineral resources have undergone processes such as crushing, grinding, and flotation to extract target minerals. Their mineral composition is mainly gangue minerals such as quartz and feldspar, and their chemical components primarily include SiO2, Al2O3, CaO, and MgO, often containing trace amounts of heavy metals and residual mineral processing reagents. The particle size distribution is typically between 0.001 mm and 2 mm, and can be further subdivided into coarse tailings (0.075 mm–2 mm) and fine tailings mud (≤0.075 mm). Hundreds of millions of tons of mineral processing tailings are discharged from mining areas annually. Large-scale stockpiling not only occupies land but also poses environmental and safety risks such as leakage, dust pollution, and landslides. Therefore, promoting their large-scale, resource-based utilization has become an urgent issue for the sustainable development of the mining industry.

[0003] With the increasing depth mining of metal mines, traditional open-face mining methods easily create large goaf areas, posing a threat of high ground pressure and causing serious consequences such as surface subsidence, roof collapses, and mechanical injuries. Therefore, the state has clearly required metal mines to backfill goaf areas. Using tailings as backfill aggregate can achieve on-site conversion of solid waste, offering environmental, economic, and safety benefits, and is a highly promising approach to tailings resource utilization.

[0004] However, the resource utilization of mineral processing tailings still faces some technical challenges. On the one hand, mineral processing tailings typically contain a high content of fine mud (≤0.075mm). This material has extremely fine particle size, large specific surface area, low activity, and high water demand. When present in large quantities, it can easily lead to increased viscosity of the backfill slurry, decreased fluidity, severe bleeding, and difficulty in encapsulating with cementitious materials. It can also easily cause insufficient early compressive strength and volume shrinkage cracking of the backfill. On the other hand, heavy metal ions (such as Cd, As, Pb, etc.) and residual chemical agents associated with mineral processing tailings can enter the backfill area along with the backfill material. If these substances seep into groundwater with water, they can easily cause water pollution and pose a long-term safety hazard to the environment.

[0005] Currently, although there are various patented technologies for preparing backfill materials using industrial solid waste, they still have their own limitations in addressing the performance synergy and environmental safety issues under conditions of high fine mud content and high admixture. 1. Application No.: 202411960424.2, Invention Title: Tunnel Support Material and Preparation Method Thereof Using High-Temperature Smelting Slag and Gypsum as Raw Materials. The tunnel support material of this invention comprises a modified cementitious material and a filling aggregate mixed in a weight ratio of 1:(0.35~0.68). The modified cementitious material comprises high-temperature smelting slag, industrial by-product gypsum, rare earth activator, ordinary cement, water-reducing agent and defoamer. The weight ratio of the high-temperature smelting slag, industrial by-product gypsum, rare earth activator, ordinary cement, water-reducing agent and defoamer is 1:(0.9~1):(0.008~0.01):(2~4):(0.01~0.025):(0.008~0.01). The research direction of this invention is to apply high-temperature smelting slag and industrial by-product gypsum to roadway support materials to improve the comprehensive utilization rate of these two solid wastes. The filling aggregates mentioned are mainly heavy calcium carbonate and quartz sand, which are industrial products with simple composition and high purity. They are not designed for industrial solid wastes such as mineral processing tailings with complex composition. At the same time, the amount of filling aggregates in the entire support material is only 26% to 40%, which is relatively low.

[0006] 2. Application No.: 202211454123.3, Invention Title: A Low-Carbon Downhole Filler and Its Preparation Method. The filler, by weight, comprises: 20-100 parts commercial cement or cementitious powder, 20-100 parts metal smelting waste slag-derived materials, 500-5000 parts mineral processing tailings, appropriate amount of water, and 5-20 parts of water-based conditioner and reinforcing agent. Its core technical approach involves pre-treating smelting waste slag through processes including pre-crushing, adding seed colloids, ball milling, and CO2 mineralization to prepare a derivative cementitious material with a specific whisker structure. This aims to replace part of the cement and, in conjunction with a dedicated water-based conditioner and reinforcing agent, achieve a high-flowability, low-bleeding filling effect. However, its research focuses on utilizing specially modified smelting waste slag to activate tailings activity. Its high-volume utilization depends on the water-based conditioner and reinforcing agent, as well as the aforementioned derivative material preparation process, resulting in high overall utilization costs. Furthermore, the scheme did not assess the heavy metal leaching toxicity of the backfill material under the condition of high tailings content, and environmental safety could not be guaranteed.

[0007] 3. Application No.: 202010595083.9, Invention Title: A Special Solidifying Agent for Solidifying Gold Mine Tailings Slurry and Its Application Method. The special solidifying agent of this invention comprises the following raw materials by mass ratio: calcium silicate 3%-7%, limestone 5%-8%, gypsum 10%-15%, silicon dioxide 0-1%, alumina 0-2%, coking desulfurization and denitrification ash 5%-10%, and slag powder 57%-77%. The application method involves mixing the solidifying agent with gold mine tailings slurry with a concentration of 60%-70% at a ratio of 1:8-10. This research focuses on using metallurgical solid waste to prepare solidifying agents for treating tailings slurry with specific concentration ranges. The material treated by this technology is a high-moisture slurry, rather than the solid or semi-solid beneficiation tailings commonly found in mines and requiring large-scale disposal. The limitation of the material state greatly restricts the universality of this technology. Meanwhile, although a high proportion of tailings slurry was incorporated, the 28-day compressive strength of the resulting solidified body was mostly above 1.7 MPa, which is relatively low. Furthermore, the leaching risk of gold mine tailings rich in cyanide and heavy metals after solidification was not assessed.

[0008] 4. Application No.: 202410459201.1, Invention Title: Method for Preparing Mine Backfill Cementitious Material Using Cyanide Tailings. This invention uses cyanide tailings, secondary aluminum ash, barium slag, and phosphogypsum as main raw materials. A cementitious agent is prepared through mixing, molding, multi-stage heating and calcination (up to 1200℃), and rapid cooling. The backfill material is then formulated using tailings as aggregate. Its core research direction is to achieve simultaneous decyanation and detoxification of cyanide tailings and mineral activation through high-temperature calcination. Although this technology utilizes hazardous solid waste, its aggregate is "tailings," not "mineral processing tailings," and therefore does not directly solve the problem of large-scale disposal of mineral processing tailings. Furthermore, the calcination process at up to 1200℃ consumes a huge amount of energy, and the complex temperature control and rapid cooling requirements result in a long process flow and high equipment investment and operating costs.

[0009] 5. Application No.: CN202410034965.6, Invention Title: A Cementitious Material for Goaf Filling, Filling Test Blocks and Their Preparation Method. This invention is a special cementitious material compounded from vanadium extraction tailings (50-70%), vanadium extraction neutralization slag (5-20%), smelting slag (0-15%), cement clinker (10-30%), and activator (2-8%). The research focuses on achieving the solidification of the cementitious material itself, that is, using the tailings and neutralization slag generated during the vanadium extraction process to replace some components in traditional cementitious materials. When this cementitious material is used to prepare filling test blocks, its mass ratio to the total tailings filling material is 1:12 to 1:4. That is, the actual mass proportion of mineral processing tailings is approximately 80% (corresponding to 1:4) to 92.3% (corresponding to 1:12). Although this dosage level is relatively high, its shortcomings lie in the fact that the performance of the filling test block depends on a specially formulated liquid activator, requiring specialized raw materials and preparation processes. Furthermore, its early compressive strength is low; examples show that the 3-day compressive strength is only 0.35-0.47 MPa, which cannot meet the engineering safety requirements of rapid support formation in underground mining operations. Similarly, with high tailings content, this invention did not conduct any assessment of the heavy metal leaching toxicity of the filling block, and environmental safety could not be guaranteed.

[0010] Therefore, there is an urgent need to develop a cementitious substrate and filling material for mine backfilling that is simple to process, can meet the early strength requirements of mine backfilling, and also has the advantages of high utilization rate of mineral processing tailings and safety and environmental protection. Summary of the Invention

[0011] The purpose of this invention is to solve the above-mentioned technical problems and provide a cementitious substrate for mine backfilling that is easy to obtain, has a simple process, can increase the amount of tailings in backfilling materials, and its preparation method, as well as a mine backfilling material with high tailings content, high strength, low water bleeding rate, good fluidity, and is safe and environmentally friendly.

[0012] To achieve the above objectives, the technical solution of the present invention is as follows: A cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, wherein the cementitious substrate for mine backfilling is modified non-ferrous metal smelting slag powder; by weight, the modified non-ferrous metal smelting slag powder comprises the following components mixed together: 75-90 parts of non-ferrous metal smelting slag; 6-15 parts fly ash; 8-16 parts of desulfurized gypsum; 5-12 parts of silicate cement; Magnesium propionate 1.5–5 parts; Calcium carbonate 1.5–5 parts; Rare earth activator 0.2–1.2 parts; Appropriate amount of flow aid; The amount of flow aid used is 0.01% to 0.1% of the total weight of the modified non-ferrous metal smelting slag powder.

[0013] As a further technical solution, the formula for calculating the addition relationship between the aforementioned magnesium propionate, calcium carbonate, and rare earth activator is: (m1 + m2) / m3 = 5 ~ 25; where m1 is the added weight of magnesium propionate, m2 is the added weight of calcium carbonate, and m3 is the added weight of rare earth activator. This ratio can achieve synergistic optimization of the hydration reaction rate and intensity development.

[0014] As a further technical solution, the non-ferrous metal smelting slag mentioned above is refined tin ore smelting slag; the main chemical components of refined tin ore smelting slag, by weight percentage, include: SiO2 35%~45%, CaO 20%~30%, Al2O3 8%~15%, Fe2O3 5%~10%, with the remainder being unavoidable impurities.

[0015] As a further technical solution, the total weight percentage of the main chemical components SiO2, Al2O3 and Fe2O3 in the above-mentioned fly ash is ≥70%, and the loss on ignition is ≤8%. The fly ash is derived from the coal combustion by-products of thermal power plants.

[0016] As a further technical solution, the rare earth activator mentioned above includes any one or more of anhydrous rare earth salts and rare earth salts containing crystal water, wherein the rare earth salt is any one or more of cerium sulfate, cerium nitrate, cerium chloride, lanthanum sulfate, and lanthanum nitrate; and the flow aid is any one or more of bentonite and magnesium aluminum silicate.

[0017] As a further technical solution, the particle size of the modified non-ferrous metal smelting slag powder described above is less than 425 mesh.

[0018] A method for preparing a cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described above, includes the following steps: (1) First ball milling: Place 75-90 parts of non-ferrous metal smelting slag dried to less than 1% by weight, 6-15 parts of fly ash and 8-16 parts of desulfurized gypsum into a ball mill and ball mill for 10-25 minutes; (2) Second ball milling: Add 5-12 parts of silicate cement, 1.5-5 parts of magnesium propionate, 1.5-5 parts of calcium carbonate, 0.2-1.2 parts of rare earth activator and the appropriate amount of flow aid to the powder after the first ball milling, and continue ball milling for 15-20 minutes to obtain modified non-ferrous metal smelting slag powder.

[0019] The mechanism of the two-stage ball milling design in this invention is as follows: the first ball milling destroys the crystal lattice structure of the raw material, and the second ball milling, after adding the modifier, achieves particle surface modification and uniform coating. Compared with the first ball milling, the compressive strength is increased by 25% to 30%, the water bleeding rate is reduced by more than 40%, and the scalability is increased by more than 20%.

[0020] As a further technical solution, the balls used in the ball mill described above are made of steel, with diameters of 80–85 mm, 55–60 mm, 30–35 mm, and 20–25 mm, and weight percentages of 15%–20%, 25%–35%, 20%–30%, and 15%–25%, respectively. This ratio design is based on the principle of particle size distribution optimization, achieving efficient crushing and uniform mixing of raw materials, and increasing the specific surface area of ​​the powder by more than 30% compared to conventional ball milling ratios.

[0021] A filling material includes mineral processing tailings and modified non-ferrous metal smelting slag powder obtained by the preparation method described above; by weight percentage, the mineral processing tailings content is 90% to 95%, and the modified non-ferrous metal smelting slag powder content is 5% to 10%.

[0022] As a further technical solution, the aforementioned tailings are tin polymetallic ore beneficiation tailings. Tin polymetallic ore beneficiation tailings are solid waste generated after crushing, grinding, and flotation of tin polymetallic ore. Fine mud (particle size ≤74μm) accounts for 60%–80% of the tailings, and the main chemical components include SiO2 65%–75%, Al2O3 10%–15%, CaO 3%–8%, MgO 1%–3%, and trace amounts of metal oxides such as Sn, Pb, and Zn. The tin polymetallic deposit is a super-large deposit located in Guangxi.

[0023] The raw material of this invention, non-ferrous metal smelting slag (such as refined tin ore smelting slag), serves as the main cementitious substrate, providing the core component for strength development; fly ash is used to fill pores and participate in hydration reactions, forming a ternary cementitious system with non-ferrous metal smelting slag and desulfurized gypsum, thereby improving strength and volume stability; desulfurized gypsum can activate the activity of non-ferrous metal smelting slag and regulate setting time; silicate cement (especially PO42.5 cement) is used to provide early strength and synergistically promotes hydration reactions with rare earth activators; magnesium propionate is used to improve the structure of hydration products and reduce bleeding rate, and its role is irreplaceable; calcium carbonate is used to optimize particle size distribution and improve density; rare earth activators are used to efficiently activate the activity of industrial solid waste and promote the generation of hydration products; flow aids are used to improve slurry fluidity and ensure smooth pipeline transportation.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The cementitious substrate for mine backfilling of the present invention, under the optimized proportions of the present invention, has three functions: efficient activation, strong bonding and heavy metal stabilization for mineral processing tailings. It can achieve a high utilization rate of over 90% for mineral processing tailings with low admixture, effectively solving the environmental geological disasters caused by the accumulation of mineral processing tailings ponds. The present invention can make the backfill material have excellent working performance with high scalability and low bleeding rate, and ensure high early and long-term compressive strength of the backfill material, while also achieving the environmental safety of the backfill material.

[0025] 2. This invention limits the addition relationship of magnesium propionate, calcium carbonate and rare earth activator to (m1+m2) / m3=2~5. Under this ratio, the synergistic optimization of hydration reaction rate and compressive strength development can be achieved.

[0026] 3. The gelling substrate of the present invention uses industrial solid waste and commercially available raw materials as the main components. The raw materials are widely available and easy to obtain. No special synthesis or complex activation treatment is required. It can be prepared by physical mixing, which is convenient for industrial production and application.

[0027] 4. The preparation method of the gel substrate for mine backfilling of the present invention is simple and streamlined. It only requires drying the raw materials and two ball milling processes to complete the preparation of the gel substrate, without relying on high-temperature calcination, chemical synthesis, or special activation processes. This method is easy to operate, consumes little energy, and can significantly reduce production costs and improve production efficiency.

[0028] 5. This invention optimizes the ball milling process by employing two-stage ball milling combined with particle size distribution optimization principles to limit the diameter and ratio of the milling media, thereby achieving efficient crushing and thorough uniform mixing of raw materials. Compared to conventional ball milling processes, the cementitious substrate prepared using the method of this invention can increase the specific surface area of ​​the powder by more than 30% and significantly improve the overall performance of the filling material: compressive strength is increased by 25%–30%, water bleeding rate is reduced by more than 40%, and scalability is increased by more than 20%, effectively optimizing the overall performance of the filling material.

[0029] 6. The mine backfill material of the present invention is prepared using the cementitious substrate of the present invention. Under the condition of high solid content of slurry concentration of 70% to 76%, it can still maintain good working performance. It has high early and long-term compressive strength (7d compressive strength 1.8 to 2.7 MPa, 28d 3.8 to 4.7 MPa, 60d 4.1 to 5.4 MPa), good working performance (spread 170 mm to 200 mm, water bleeding rate 7.0% to 11.8%), and takes into account both high strength and excellent fluidity. Moreover, the heavy metal leaching toxicity of the mine backfill material of the present invention meets the requirements of the "Identification Standard for Hazardous Waste Leaching Toxicity Identification" (GB5085.3-2007), thus achieving the unity of high content of mineral processing tailings, excellent comprehensive performance and environmental safety.

[0030] 7. This invention also significantly improves the resource utilization rate of other industrial solid wastes, with the utilization rate of non-ferrous metal smelting slag reaching 75% to 90% and the utilization rate of desulfurization gypsum reaching 12% to 18%. Attached Figure Description

[0031] Figure 1 This is a scanning electron microscope image of the filling material sample from Example 1 of the present invention; Figure 2 This is the EDS spectrum of the filling material sample in Example 1 of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the scope shown in the embodiments.

[0033] The non-ferrous metal smelting slag in this embodiment of the invention is refined tin ore smelting slag, which originates from the industrial solid waste of a non-ferrous metal smelting plant in Guangxi; the fly ash and desulfurization gypsum originate from a thermal power plant in Guangxi; and the beneficiation tailings originate from the industrial solid waste of a mining company in Guangxi. The weight content of their main chemical components is shown in Table 1. Table 1

[0034] The main chemical component of the desulfurized gypsum of the present invention is calcium sulfate dihydrate (CaSO4·2H2O), with a dry basis content of 88% to 90%.

[0035] Example 1: (1) Preparation of cementitious substrate: 10 kg of refined tin ore smelting slag (83.3 parts), 0.9 kg of fly ash (7.5 parts), and 1.2 kg of desulfurized gypsum (10 parts) were dried to a moisture content of 0.8%; then the dried refined tin ore smelting slag, fly ash, and desulfurized gypsum were placed in a ball mill and ball milled for 12 minutes for the first time; then 0.8 kg of PO42.5 cement (6.7 parts), 0.25 kg of magnesium propionate (2.1 parts), and 0.25 kg of calcium carbonate were added to the ball mill. (2.1 parts), 0.05 kg cerium nitrate hexahydrate (0.4 parts) and 0.002 kg bentonite (flow aid, accounting for 0.017% of the total weight of modified non-ferrous metal smelting slag powder) were ball-milled for 18 minutes to obtain modified non-ferrous metal smelting slag powder with a particle size of 425 mesh; the ball mill steel balls were configured as follows: 85 mm (20% by weight), 55 mm (30% by weight), 35 mm (25% by weight), and 25 mm (25% by weight). (2) Preparation of filling material: Take 0.33 kg of modified non-ferrous metal smelting slag powder, 5 kg of tin polymetallic ore beneficiation tailings (ash-sand ratio 1:15), add 2.1 kg of water, and stir evenly to obtain a filling material with a slurry concentration of 72%.

[0036] The scanning electron microscope (SEM) image and EDS spectrum of the filling material sample in Example 1 of this invention are as follows: Figure 1 and Figure 2 As shown. From Figure 1 It is evident that the microstructure of the modified non-ferrous metal smelting slag powder exhibits characteristics of "dense gel network + tightly packed particles," with a large amount of fine and amorphous flocculent CSH gel being the core source of the compressive strength of the filling material. Figure 2 The EDS energy dispersive spectroscopy showed that the main elements of the modified non-ferrous metal smelting slag powder were Si, Ca, Al and Fe, while Mg and S were also detected.

[0037] Example 2:

[0038] (1) Preparation of cementitious substrate: 10 kg of refined tin ore smelting slag (84.7 parts), 1 kg of fly ash (8.5 parts), and 1.1 kg of desulfurized gypsum (9.3 parts) were dried to a moisture content of 0.6%; then the dried refined tin ore smelting slag, fly ash, and desulfurized gypsum were placed in a ball mill and ball milled for 12 minutes for the first time; then 0.8 kg of PO42.5 cement (6.8 parts), 0.25 kg of magnesium propionate (2.1 parts), and 0.25 kg of calcium carbonate were added to the ball mill. (2.1 parts), 0.05 kg cerium nitrate hexahydrate (0.4 parts), and 0.002 kg magnesium aluminum silicate (flow aid, accounting for 0.017% of the modified non-ferrous metal smelting slag powder) were ball-milled for a second time for 18 minutes to obtain modified non-ferrous metal smelting slag powder with a particle size of 420 mesh; the ball mill steel balls were configured as follows: 85 mm (20% by weight), 55 mm (30% by weight), 35 mm (25% by weight), and 25 mm (25% by weight). (2) Preparation of filling material: Take 0.33 kg of modified non-ferrous metal smelting slag powder, 5 kg of tin polymetallic ore beneficiation tailings (ash-sand ratio 1:15), add 1.7 kg of water, stir evenly to obtain a filling material with a slurry concentration of 76%.

[0039] Example 3:

[0040] (1) Preparation of cementitious substrate: 10 kg of refined tin ore smelting slag (83.3 parts), 1 kg of fly ash (8.3 parts), and 1.1 kg of desulfurized gypsum (9.2 parts) were dried to a moisture content of 0.7%. Then, the dried refined tin ore smelting slag, fly ash, and desulfurized gypsum were placed in a ball mill and ball milled for 12 minutes for the first time. Then, 0.9 kg of PO42.5 cement (7.5 parts), 0.25 kg of magnesium propionate (2.1 parts), and 0.25 kg of carbon were added to the ball mill. Calcium sulfate (2.1 parts), 0.05 kg lanthanum nitrate (0.4 parts), and 0.002 kg magnesium aluminum silicate (flow aid, accounting for 0.016% of the modified non-ferrous metal smelting slag powder) were ball-milled for a second time for 18 minutes to obtain modified non-ferrous metal smelting slag powder with a particle size of 410 mesh; the ball mill steel balls were configured as follows: 85 mm (20% by weight), 55 mm (30% by weight), 35 mm (25% by weight), and 25 mm (25% by weight). (2) Preparation of filling material: Take 0.41 kg of modified non-ferrous metal smelting slag powder, 5 kg of tin polymetallic ore beneficiation tailings (ash-sand ratio 1:12), add 2.15 kg of water to obtain a filling material with a slurry concentration of 72%.

[0041] The filling materials of Examples 1-3 of this invention were subjected to performance testing using standard test blocks of 70.7mm×70.7mm×70.7mm. The testing was conducted according to JGJ / T70-2009 "Standard for Basic Performance Test Methods of Building Mortar" and GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The results are shown in Table 2.

[0042] Table 2

[0043] As can be seen from Table 2, by applying the cementitious substrate of the present invention, the final filling material product has high early and long-term compressive strength, excellent fluidity and low bleeding rate; and the heavy metal leaching toxicity of the filling material for mine filling of the present invention meets the requirements of the "Identification Standard for Hazardous Waste - Leaching Toxicity Identification" (GB5085.3-2007), thus achieving a balance between high content of mineral processing tailings, excellent comprehensive performance and environmental safety.

[0044] Comparative experiment (1) Single ball milling and double ball milling Comparative Example 1: The ball milling process in Example 1 was changed to a single ball milling process, with a single ball milling time of 30 minutes; other steps and parameters were the same as in Example 1.

[0045] The results obtained are compared with those of Example 1, as shown in Table 3: Table 3

[0046] As shown in Table 3, the secondary ball milling process adopted in this invention not only effectively increases the specific surface area of ​​the modified non-ferrous metal smelting slag powder, but also reduces the bleeding rate by 40.3%, increases the spread by 20%, and ultimately increases the compressive strength of the filling material by 31%. This effectively improves the working performance and mechanical properties of the filling material.

[0047] (2) Comparison of steel ball configurations Comparative Example 2: The steel ball configuration of the ball mill in Example 1 was changed to be consistent with the configuration of industrial ball mills for cement production, while other steps and parameters were the same as in Example 1.

[0048] The results obtained are compared with those of Example 1, as shown in Table 4: Table 4

[0049] As shown in Table 4, the steel ball configuration used in this invention can significantly increase the specific surface area of ​​the modified non-ferrous metal smelting slag powder, making the cementitious powder particles have more exposed active sites and a larger contact area with water, resulting in faster and more complete hydration reaction initiation and a significant improvement in 7-day compressive strength, thus providing a good guarantee for the early compressive strength of the filling material.

[0050] (3) Other cementitious substrates and the cementitious substrate of the present invention Comparative Example 3: The same filling material preparation steps as in Example 1 of this invention were used, except that the cementitious substrate was replaced with the modified cementitious material of Example 2, patent application number CN202411960424.2. The results obtained were compared with those of Example 1, as shown in Table 5: Table 5

[0051] As shown in Table 5, Example 2 of application number CN202411960424.2 achieves a certain compressive strength when using the specified modified cementitious material and heavy calcium carbonate aggregate ratio. However, when the aggregate is replaced with the tailings used in Example 1 of this invention, and the corresponding material ratio of this invention is adopted, the 7-day and 28-day compressive strengths of the filling material are significantly lower than those of Example 1 of this invention, and the bleeding rate also increases significantly. This indicates that the prior art cannot achieve the same level of working performance and mechanical properties under similar high tailings content conditions as this invention.

[0052] (4) Magnesium propionate substitution experiment Comparative Example 4: Magnesium propionate in Example 1 was changed to magnesium sulfate, while other steps and parameters were the same as in Example 1.

[0053] Comparative Example 5: Magnesium propionate in Example 1 was changed to magnesium chloride, while other steps and parameters were the same as in Example 1.

[0054] The results obtained are compared with those of Example 1, as shown in Table 6: Table 6

[0055] Table 6 shows that the cementitious material exhibits the best overall performance when magnesium propionate is used as the raw material. In contrast, when magnesium sulfate is used, the early strength is lower, the compressive strength decreases by about 21%, and the bleeding rate increases by 35%; while when magnesium chloride is used, the compressive strength decreases by 18%, and the bleeding rate also increases by 27%. This indicates that magnesium propionate has irreplaceable advantages in improving compressive strength and reducing bleeding rate.

[0056] (5) The relationship between magnesium propionate, calcium carbonate and rare earth activators Comparative Example 6: The magnesium propionate, calcium carbonate, and cerium nitrate hexahydrate (m1+m2) / m3 < 5 in Example 1 were changed to 0.1 kg, 0.1 kg, and 0.05 kg, respectively. Other steps and parameters were the same as in Example 1.

[0057] Comparative Example 7: The magnesium propionate, calcium carbonate, and cerium nitrate hexahydrate (m1+m2) / m3 > 25 in Example 1 were changed to 0.1 kg, 0.1 kg, and 0.005 kg, respectively. Other steps and parameters were the same as in Example 1.

[0058] The results obtained are compared with those of Example 1, as shown in Table 7: Table 7

[0059] As shown in Table 7, the 7-day strength (2.3 MPa) of Example 1 is significantly higher than that of Comparative Example 6 (1.5 MPa) and Comparative Example 7 (1.8 MPa). This indicates that when (m1+m2) / m3 = 10 is within the optimized range of 5–25, the catalytic activity of cerium nitrate is fully activated, complementing the pH adjustment of magnesium propionate and the ion replenishment of calcium carbonate. This results in a short hydration induction period and a sufficient reaction during the acceleration period. Furthermore, Example 1 exhibits a superior spread (180 mm), demonstrating good slurry fluidity and uniform distribution of hydration products. Comparative Example 6, due to its low (m1+m2) / m3 ratio, suffers from insufficient ion replenishment and a low amount of hydration products. Comparative Example 7, with its excessively high (m1+m2) / m3 ratio, suffers from insufficient rare earth catalyst, leading to a slower reaction rate. This suggests that when the synergistic effect of the three factors fails, it can easily result in insufficient hydration and a loose structure in the later stages.

[0060] The above embodiments are merely specific examples to further illustrate the purpose, technical solution, and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent substitutions, improvements, etc., made within the scope of the disclosure of the present invention are included within the protection scope of the present invention.

Claims

1. A cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, characterized in that, The cementitious substrate for mine backfilling is modified non-ferrous metal smelting slag powder; by weight, the modified non-ferrous metal smelting slag powder comprises the following components mixed together: 75-90 parts of non-ferrous metal smelting slag; 6-15 parts fly ash; 8-16 parts of desulfurized gypsum; 5-12 parts of silicate cement; Magnesium propionate 1.5–5 parts; Calcium carbonate 1.5–5 parts; Rare earth activator 0.2–1.2 parts; Appropriate amount of flow aid; The amount of flow aid used is 0.01% to 0.1% of the total weight of the modified non-ferrous metal smelting slag powder.

2. The cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described in claim 1, is characterized in that... The formula for calculating the addition relationship between magnesium propionate, calcium carbonate and rare earth activator is: (m1+m2) / m3=5~25; where m1 is the added weight of magnesium propionate, m2 is the added weight of calcium carbonate and m3 is the added weight of rare earth activator.

3. The cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described in claim 1, is characterized in that... The non-ferrous metal smelting slag is refined tin ore smelting slag; the main chemical components of refined tin ore smelting slag, by weight percentage, include: SiO2 35%~45%, CaO 20%~30%, Al2O3 8%~15%, Fe2O3 5%~10%, with the remainder being unavoidable impurities.

4. The cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described in claim 1, is characterized in that: The fly ash contains SiO2, Al2O3 and Fe2O3, whose total weight percentage is ≥70% and loss on ignition is ≤8%.

5. The cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing according to claim 1, characterized in that: The rare earth activator includes any one or more of anhydrous rare earth salts and rare earth salts containing crystal water, wherein the rare earth salt is any one or more of cerium sulfate, cerium nitrate, cerium chloride, lanthanum sulfate, and lanthanum nitrate; and the flow aid is any one or more of bentonite and magnesium aluminum silicate.

6. The cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing according to claim 1, characterized in that: The particle size of the modified non-ferrous metal smelting slag powder is less than 425 mesh.

7. A method for preparing a cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) First ball milling: Place 75-90 parts of dried non-ferrous metal smelting slag, 6-15 parts of fly ash and 8-16 parts of desulfurized gypsum into a ball mill and ball mill for 10-25 minutes; (2) Second ball milling: Add 5-12 parts of silicate cement, 1.5-5 parts of magnesium propionate, 1.5-5 parts of calcium carbonate, 0.2-1.2 parts of rare earth activator and the appropriate amount of flow aid to the powder after the first ball milling, and continue ball milling for 15-20 minutes to obtain modified non-ferrous metal smelting slag powder.

8. The method for preparing a cementitious substrate for mine backfilling that can increase the content of tailings in mineral processing, as described in claim 7, is characterized in that: The balls used in the ball mill are made of steel and have diameters of 80–85 mm, 55–60 mm, 30–35 mm, and 20–25 mm, respectively, with weight percentages of 15%–20%, 25%–35%, 20%–30%, and 15%–25%, respectively.

9. A filling material, characterized in that: It includes mineral processing tailings and modified non-ferrous metal smelting slag powder obtained by the preparation method as described in claim 8 or 9; by weight percentage, the mineral processing tailings content is 90% to 95%, and the modified non-ferrous metal smelting slag powder content is 5% to 10%.

10. The filling material according to claim 1, characterized in that: The tailings are tin polymetallic ore tailings, and the weight of fine mud with a particle size ≤74μm accounts for 60% to 80% of the tin polymetallic ore tailings.

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