Calcium oxide-phosphate synergistically excited copper slag-based cementing material as well as preparation method and application thereof

Abstract

The invention discloses a calcium oxide-phosphate synergistically excited copper slag-based cementing material as well as a preparation method and application thereof, and belongs to the technical field of resource utilization of industrial solid wastes. Comprising the following raw materials in parts by weight: 60-80 parts of copper slag, 15-30 parts of a high-aluminum admixture, 5-10 parts of phosphogypsum, 3-8 parts of calcium oxide, 4-12 parts of dipotassium phosphate and 0.05-0.3 part of triisopropanolamine. According to the invention, a fayalite structure is destroyed through alkali excitation of calcium oxide, phosphate gel is formed by dipotassium phosphate and dissolved Fe < 2 + >, ion dissolution is accelerated through chelating of triisopropanolamine, and a phosphate-ettringite composite gelling system is constructed by combining ettringite generated by a high-aluminum material and ardealite. The material mainly comprises copper slag and other solid wastes, and has the advantages of good heavy metal curing effect, environmental protection and low carbon. When the filling agent is applied to filling of gold tailings, the ratio of ash to sand is 1: 8, and the filling concentration is 64 angstroms; the prepared filling body can still keep good working performance and mechanical strength under the working condition that the leaching concentration is larger than 66%, the excellent curing effect on the specific pollutant arsenic (As) in the gold ore tailings is achieved, and the leaching concentration is obviously lower than the standard limit value.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource utilization technology, specifically relating to a cementing material with copper slag as the main raw material and its preparation method, particularly to a copper slag-based cementing material synergistically activated by calcium oxide and phosphate and its application in mine backfilling, especially in gold mine tailings backfilling. Background Technology

[0002] Copper slag is a waste product generated during pyrometallurgical copper smelting, with its emissions approximately 2-3 times the amount of metallic copper produced. This copper slag is characterized by its fine particle size, diverse types, and complex composition, and its resource utilization rate is low. It is primarily stored in stockpiles, accumulating to hundreds of millions of tons to date. The long-term abandonment of copper slag occupies land and severely impacts water quality and the environment, making the development of efficient resource utilization of copper slag imperative.

[0003] To address the problem of copper slag storage, many researchers have utilized metallurgical slag to prepare novel cementitious materials for use in mine cementing and filling. However, in the current copper smelting process using the "twin flash furnace" method, the copper slag is the tailings after slow cooling and flotation of the smelting slag. Its amorphous phase content is extremely low (typically <5%), with the main crystalline phases being inert fir olivine (Fe2SiO4) and magnetite (Fe3O4). Most of the SiO2 exists in the form of fir olivine crystals (i.e., ferrosilicon), which hardly participates in hydration, resulting in poor pozzolanic reactivity and low efficiency of traditional alkali activation. Furthermore, the copper slag has low alumina and calcium oxide content, making it difficult to form C-(A)-SH gel or ettringite. In existing solutions, traditional alkali activators such as sodium hydroxide and water glass cannot dissociate the stable structure of fir olivine, and high-alumina admixtures rely on external calcium sources to generate ettringite, resulting in poor compatibility with the copper slag system.

[0004] Meanwhile, the large amount of tailings generated from gold mining also requires safe disposal. Utilizing solid waste such as copper slag to prepare cementitious materials for gold mine tailings backfilling can achieve "waste treatment with waste," offering both environmental and economic benefits. To control costs and meet pipeline transportation requirements, gold mine tailings backfilling often employs lower cementitious material content (high ash-to-sand ratio, such as 1:8) and specific slurry concentrations (such as 64-66%), which places higher demands on the activation efficiency and early strength of the cementitious materials. An even more serious challenge is that gold mine tailings may contain characteristic pollutants such as arsenic (As), posing a threat to the long-term environmental safety of the backfill.

[0005] Therefore, developing a novel cementitious material that can dissociate the stable structure of fir olivine, has good compatibility with copper slag systems, and can effectively solidify harmful substances such as arsenic is key to promoting the co-use of solid waste in gold mine tailings backfilling. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate, its preparation method, and its application. This material can efficiently activate copper slag under specific working conditions of a ash-sand ratio of 1:8 and a filling concentration of 64-66%, and achieve efficient stabilization of pollutants such as arsenic in gold mine tailings.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate, comprising the following raw materials in parts by weight: The ingredients are: 60-80 parts copper slag, 15-30 parts high-alumina admixture, 5-10 parts phosphogypsum, 3-8 parts calcium oxide, 4-12 parts dipotassium hydrogen phosphate, and 0.05-0.3 parts triisopropanolamine.

[0008] Beneficial effects: The calcium oxide (CaO)-dipotassium hydrogen phosphate (K2HPO4)-triisopropanolamine (TIPA) in this invention have a synergistic effect of three components: calcium oxide dissolves in water, providing an alkaline environment (pH>12), which breaks the Fe-O-Si bonds in Fe2SiO4 and promotes Fe... 2+ Dissolution breaks the inertness of the fuchsin crystals; the PO4 released from the dissolution of dipotassium hydrogen phosphate (K2HPO4) 3- With dissolved Fe 2 + The FePO4 gel is formed, creating a phosphate network structure that replaces the silica-alumina gel to provide bulk strength; triisopropanolamine (TIPA) chelates Fe... 2+ It accelerates ion dissolution (increasing dissolution rate by >40%) and also shortens setting time, improving the slow early strength development defect. Meanwhile, high-alumina admixtures (such as coal gangue powder / red mud / fly ash, Al2O3 content ≥30%) can provide aluminate, which, along with SO4 provided by phosphogypsum, contributes to the process. 2- In an alkaline environment, needle-like ettringite (AFt) is generated, filling pores and enhancing early strength. Furthermore, phosphate gel and ettringite interlock to form a "phosphate framework + sulfate filler" composite structure, thus creating an ettringite-phosphate-composite cementing system. This system can meet the performance requirements of cementing materials in various engineering scenarios. Moreover, the cementing material provided by this invention uses copper slag as the main raw material, reducing dependence on natural resources and minimizing environmental pollution caused by copper slag stockpiling, resulting in significant economic and environmental benefits.

[0009] Preferably, the mass fraction of Al2O3 in the high-alumina admixture is ≥30%.

[0010] Preferably, the high-alumina admixture includes one or more of the following industrial solid wastes rich in alumina: fly ash, red mud, and coal gangue.

[0011] Beneficial effects: Under the above conditions, Al2O3 in the high-alumina admixture can provide sufficient aluminate ions for the formation of acicular ettringite (AFt), ensuring sufficient reactants to generate ettringite in an alkaline environment. This more effectively fills the pores, improves the early strength and overall density of the cementitious material, and further optimizes its performance. Furthermore, fly ash, red mud, and coal gangue are widely available, inexpensive, and mostly industrial waste. Applying them to copper slag-based cementitious materials achieves resource utilization of waste, reduces production costs, and minimizes environmental pollution from these industrial wastes, resulting in significant environmental and economic benefits.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned calcium oxide-phosphate synergistically activated copper slag-based cementitious material, comprising the following steps: An ethanol solution of triisopropanolamine was sprayed into copper slag and calcium oxide, and then ground to obtain fine copper slag composite powder. The high-alumina admixture is premixed with phosphogypsum to obtain a premix; the premix is ​​then mixed evenly with the finely ground copper slag composite powder in a dry powder state, and finally dipotassium hydrogen phosphate is added. The mixture is then placed in a sealed container and stirred for 3-10 minutes to obtain the copper slag-based cementitious material.

[0013] More preferably, the mass concentration of the triisopropanolamine ethanol solution is 1-5%.

[0014] Beneficial effects: By spraying an ethanol solution of triisopropanolamine into copper slag and calcium oxide, the triisopropanolamine can be uniformly dispersed and fully contacted with the copper slag and calcium oxide. This promotes the interaction between the components during grinding, which is beneficial for subsequent reactions. Furthermore, this invention, by mixing the premix formed from high-alumina admixtures and phosphogypsum with finely ground copper slag composite powder and dipotassium hydrogen phosphate, can form a copper slag-based cementitious material with specific structure and properties. The entire preparation method is simple, easy to operate, and readily applicable to industrial production. It effectively ensures the synergistic effect between the raw materials, resulting in a high-performance copper slag-based cementitious material.

[0015] Preferably, the grinding is performed until the specific surface area is ≥450m². 2 / kg, more preferably 500-550m 2 / kg.

[0016] Beneficial effects: The above grinding conditions increase the particle surface area of ​​the raw materials and improve their reactivity, allowing the raw materials to come into more full contact and react in subsequent reactions, thereby accelerating the reaction rate, increasing the degree of reaction, and further improving the performance of copper slag-based cementitious materials.

[0017] Thirdly, the present invention provides the application of the above-mentioned copper slag-based cementitious material in mine backfilling, which is particularly suitable for backfilling projects using gold mine tailings as aggregate.

[0018] Fourthly, the present invention provides a mine backfill slurry, comprising the following raw materials: The above-mentioned copper slag-based cementitious material, gold mine tailings and water; wherein, the mass ratio of cementitious material to gold mine tailings is 1:8, and the mass concentration of filling slurry is 64-66%.

[0019] More preferably, the gold mine tailings are full-grain-size gold mine tailings.

[0020] Preferably, the slump of the mine filling slurry is 210-240 mm to meet the requirements of gravity-flow transportation in gold mine filling pipelines.

[0021] Fifthly, the present invention provides a method for preparing the above-mentioned mine backfill slurry, wherein the copper slag-based cementitious material, gold mine tailings and water are mixed and stirred according to the mass ratio until a homogeneous slurry with no or slight water leakage is obtained, which is the mine backfill slurry.

[0022] Beneficial effects: Under the above conditions, it is easy to transport and pour during the mine filling process, and can be smoothly filled into various voids in the mine, ensuring the compactness of the filling; at the same time, the slurry within this slump range will not exhibit segregation, bleeding or other phenomena due to excessive fluidity, ensuring the quality stability of the filling slurry and helping to improve the overall performance of the mine filling body.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects: (1) Innovative synergistic activation mechanism - "calcium oxide-dipotassium hydrogen phosphate-triisopropanolamine" triple synergy: This invention realizes the Fe in iron olivine through CaO base dissociation + TIPA chelation dissolution. 2+ The efficient release of olivine forms a "CaO-TIPA" activation pathway. Simultaneously, this invention also includes a phosphate-ettling aluminate composite cementing phase, which promotes the formation of a "rigid-flexible" structure between the phosphate gel (FePO4) and ettling aluminate (AFt), overcoming the strength bottleneck of a single phase. This allows the material to maintain high reactivity and strength even at a relatively low ash-to-sand ratio (1:8).

[0024] (2) Excellent arsenic curing ability: The phosphate gel (FePO4) and hydrated products such as ettringite formed in the system have excellent curing ability for arsenates (AsO4). 3- It has strong adsorption, coprecipitation and ion exchange effects, which can firmly fix it in the cementitious network structure, significantly reduce the risk of arsenic leaching and ensure the environmental safety of the filling body.

[0025] (3) Good engineering adaptability: In the concentration range of 64-66%, the fluidity of the filling grout (slump 210-240mm) is moderate, which is conducive to pipeline transportation and can reduce bleeding and segregation, thus ensuring the uniformity and density of the filling body.

[0026] (4) High efficiency and low cost of solid waste: This invention utilizes solid waste synergistic design, copper slag (aluminum-deficient calcium) and high-aluminum material (aluminum-rich) complement each other, and phosphogypsum provides calcium and sulfur sources at the same time, realizing cementless preparation of cementitious materials, realizing waste treatment, and has important significance for low carbon and environmental protection. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 The results are from XRD analysis of copper slag. Figure 2 These are the results of laser particle size analysis of copper slag. Figure 3 The results are from laser particle size analysis of tailings from a gold mine in Lhasa. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] This invention provides a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate, comprising the following raw materials in parts by weight: The ingredients are: 60-80 parts copper slag, 15-30 parts high-alumina admixture, 5-10 parts phosphogypsum, 3-8 parts calcium oxide, 4-12 parts dipotassium hydrogen phosphate, and 0.05-0.3 parts triisopropanolamine.

[0031] In a preferred embodiment, the mass fraction of Al2O3 in the high-alumina admixture is ≥30%.

[0032] In a preferred embodiment, the high-alumina admixture includes one or more of fly ash, red mud, and coal gangue.

[0033] This invention also provides a method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate, comprising the following steps: An ethanol solution of triisopropanolamine was sprayed into copper slag and calcium oxide, and then ground to obtain fine copper slag composite powder. The high-alumina admixture is premixed with phosphogypsum to obtain a premix; the premix is ​​then mixed evenly with the finely ground copper slag composite powder in a dry powder state, and finally dipotassium hydrogen phosphate is added. The mixture is then placed in a sealed container and stirred for 3-10 minutes to obtain the copper slag-based cementitious material.

[0034] This invention also provides an application of a calcium oxide-phosphate synergistic activated copper slag-based cementitious material in mine backfilling, especially in gold mine tailings backfilling.

[0035] This invention also provides a mine backfill slurry, the raw materials of which are copper slag-based cementitious material, gold mine tailings and water, wherein the mass ratio of cementitious material to gold mine tailings is 1:8 and the mass concentration of the backfill slurry is 64-66%.

[0036] In a preferred embodiment, the slump of the mine filling slurry is 210-240 mm.

[0037] This invention also provides a method for preparing mine backfill slurry, comprising the following steps: The copper slag-based cementitious material, gold mine tailings, and water are mixed and stirred according to the mass ratio until a homogeneous slurry with no or slight water leakage is obtained, which is the mine filling slurry.

[0038] Unless otherwise specified, all raw materials used in the embodiments of this invention are obtained through commercial channels, wherein: The copper slag was supplied by Yangxin Hongsheng Copper Industry Co., Ltd., and was produced using a "suspension flash smelting + suspension flash blowing" process. It is the tailings from the flash smelting furnace slag after slow cooling and mineral processing. Its main components are shown in Table 1 below, and the XRD analysis results are as follows. Figure 1 The particle size distribution was analyzed by a laser particle size analyzer as follows: Figure 2 As shown, its D V (50) = 16.0 μm.

[0039] Table 1 Main chemical components of copper slag The high-alumina admixture was obtained by mixing fly ash (Class F), red mud and coal gangue in a mass ratio of 1:1:1, drying and grinding them together until the particle size was ≤45μm. The Al2O3 content of the admixture was measured to be 35.2%.

[0040] The SO3 content of phosphogypsum is 38.5%. It should be dried before use and the particle size should be <45μm.

[0041] The gold mine tailings are full-size tailings from a gold mine in Lhasa, with a particle size distribution of D. v (10) = 1.88 μm, D v (25) = 4.87 μm, D v (50) = 18.6 μm, D v (90) = 109 μm (see details) Figure 3 Its arsenic content is 550 mg / kg.

[0042] The calcium oxide is industrial grade, with a total calcium content of ≥90%. Dipotassium hydrogen phosphate is industrial grade, with a purity of 98%. Triisopropanolamine is chemically pure, with a purity of 99%.

[0043] Unless otherwise specified, room temperature or normal temperature in the embodiments of the present invention refers to 25±3℃.

[0044] Example 1 A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 70 parts copper slag, 20 parts high-alumina admixture, 6 parts phosphogypsum, 5 parts calcium oxide, 8 parts dipotassium hydrogen phosphate, and 0.1 parts triisopropanolamine.

[0045] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate includes the following steps: (1) Dissolve 0.1 parts by weight of triisopropanolamine in 4 parts by weight of anhydrous ethanol to prepare an ethanol solution of triisopropanolamine; pour copper slag and calcium oxide into a ball mill, spray the above-mentioned ethanol solution of triisopropanolamine into it, and grind them together for 50 min to obtain a specific surface area of ​​510 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture and phosphogypsum are premixed to obtain a premix. The premix is ​​then mixed evenly with the finely ground copper slag composite powder obtained in step (1), and then dipotassium hydrogen phosphate is added. The mixture is sealed and stirred for 5 minutes to obtain copper slag-based cementitious material A1.

[0046] Example 2 A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 75 parts copper slag, 15 parts high-alumina admixture, 5 parts phosphogypsum, 4 parts calcium oxide, 6 parts dipotassium hydrogen phosphate, and 0.2 parts triisopropanolamine.

[0047] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate includes the following steps: (1) Dissolve 0.1 parts by weight of triisopropanolamine in 4 parts by weight of anhydrous ethanol to prepare an ethanol solution of triisopropanolamine; pour copper slag and calcium oxide into a ball mill, spray the above-mentioned ethanol solution of triisopropanolamine into it, and grind them together for 45 min to obtain a specific surface area of ​​490 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture and phosphogypsum are premixed to obtain a premix. The premix is ​​then mixed evenly with the finely ground copper slag composite powder obtained in step (1), and then dipotassium hydrogen phosphate is added. The mixture is sealed and stirred for 5 minutes to obtain copper slag-based cementitious material A2.

[0048] Example 3 A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 65 parts copper slag, 25 parts high-alumina admixture, 8 parts phosphogypsum, 6 parts calcium oxide, 10 parts dipotassium hydrogen phosphate, and 0.15 parts triisopropanolamine.

[0049] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate includes the following steps: (1) Dissolve 0.1 parts by weight of triisopropanolamine in 4 parts by weight of anhydrous ethanol to prepare an ethanol solution of triisopropanolamine; pour copper slag and calcium oxide into a ball mill, spray the above-mentioned ethanol solution of triisopropanolamine into it, and grind them together for 55 min to obtain a specific surface area of ​​530 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture and phosphogypsum are premixed to obtain a premix. The premix is ​​then mixed evenly with the finely ground copper slag composite powder obtained in step (1), and then dipotassium hydrogen phosphate is added. The mixture is sealed and stirred for 5 minutes to obtain copper slag-based cementitious material A3.

[0050] Example 4 (Changes in the source of copper slag) A calcium oxide-phosphate synergistic activated copper slag-based cementitious material differs from Example 1 only in that the copper slag used is a copper slag from Zambia, the main components of which are shown in Table 2.

[0051] Table 2. Main chemical components of a copper slag from Zambia A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate includes the following steps: (1) Dissolve 0.1 parts by weight of triisopropanolamine in 4 parts of anhydrous ethanol to prepare an ethanol solution of triisopropanolamine; pour Zambian copper slag and calcium oxide into a ball mill, spray the above-mentioned ethanol solution of triisopropanolamine into it, and grind them together for 55 min to obtain a specific surface area of ​​515 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture and phosphogypsum are premixed to obtain a premix. The premix is ​​then mixed evenly with the finely ground copper slag composite powder obtained in step (1), and then dipotassium hydrogen phosphate is added. The mixture is sealed and stirred for 5 minutes to obtain copper slag-based cementitious material A4.

[0052] Example 5 (Adjustment of high-alumina admixture ratio) A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 70 parts copper slag, 25 parts high-alumina admixture (fly ash, red mud and coal gangue mixed in a mass ratio of 2:2:1), 7 parts phosphogypsum, 5 parts calcium oxide, 9 parts dipotassium hydrogen phosphate, and 0.1 parts triisopropanolamine.

[0053] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate is the same as in Example 1, yielding cementitious material A5.

[0054] Example 6 (Lower limit of activator dosage) A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 60 parts copper slag, 30 parts high-alumina admixture, 10 parts phosphogypsum, 3 parts calcium oxide, 4 parts dipotassium hydrogen phosphate, and 0.05 parts triisopropanolamine.

[0055] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate is the same as in Example 1, yielding cementitious material A6.

[0056] Example 7 (Upper Limit of Activator Dosage) A calcium oxide-phosphate synergistic activated copper slag-based cementitious material, comprising the following raw materials in parts by weight: 80 parts copper slag, 15 parts high-alumina admixture, 5 parts phosphogypsum, 8 parts calcium oxide, 12 parts dipotassium hydrogen phosphate, and 0.3 parts triisopropanolamine.

[0057] A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate is the same as in Example 1, yielding cementitious material A7.

[0058] Comparative Example 1 (without calcium oxide) A copper slag-based cementitious material, differing from Example 1 only in that calcium oxide is replaced with an equal mass of copper slag, specifically comprising the following raw materials in parts by weight: 75 parts copper slag, 20 parts high-alumina admixture, 6 parts phosphogypsum, 8 parts dipotassium hydrogen phosphate, and 0.1 parts triisopropanolamine.

[0059] A method for preparing a copper slag-based cementitious material is the same as in Example 1, yielding cementitious material D1.

[0060] Comparative Example 2 (without dipotassium hydrogen phosphate) A copper slag-based cementitious material, differing from Example 1 only in that dipotassium hydrogen phosphate is replaced with an equal mass of copper slag, specifically comprising the following raw materials in parts by weight: 78 parts copper slag, 20 parts high-alumina admixture, 6 parts phosphogypsum, 5 parts calcium oxide, and 0.1 parts triisopropanolamine.

[0061] A method for preparing a copper slag-based cementitious material is the same as in Example 1, yielding cementitious material D2.

[0062] Comparative Example 3 (without triisopropanolamine) A copper slag-based cementitious material, differing from Example 1 only in that it does not include triisopropanolamine, and specifically comprises the following raw materials in parts by weight: 70 parts copper slag, 20 parts high-alumina admixture, 6 parts phosphogypsum, 5 parts calcium oxide, and 8 parts dipotassium hydrogen phosphate.

[0063] A method for preparing a copper slag-based cementitious material includes the following steps: (1) Copper slag and calcium oxide were poured into a ball mill and ground together for 50 minutes to obtain a specific surface area of ​​510 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture and phosphogypsum are premixed to obtain a premix. The premix is ​​then mixed evenly with the finely ground copper slag composite powder obtained in step (1), and then dipotassium hydrogen phosphate is added. The mixture is sealed and stirred for 5 minutes to obtain copper slag-based cementitious material D3.

[0064] Comparative Example 4 (phosphogypsum-free) A copper slag-based cementitious material, differing from Example 1 only in that phosphogypsum is replaced with an equal mass of copper slag, specifically comprising the following raw materials in parts by weight: 76 parts copper slag, 20 parts high-alumina admixture, 5 parts calcium oxide, 8 parts dipotassium hydrogen phosphate, and 0.1 parts triisopropanolamine.

[0065] A method for preparing a copper slag-based cementitious material is the same as in Example 1, yielding cementitious material D4.

[0066] Comparative Example 5 (Replacement of Traditional Alkali Activator) A copper slag-based cementitious material differs from Example 1 only in that dipotassium hydrogen phosphate and calcium oxide are replaced with equimolar amounts of sodium silicate solid and sodium hydroxide solid, in an attempt to provide similar alkalinity but without phosphate and a specific calcium source. Specifically, it comprises the following raw materials in parts by weight: 70 parts copper slag, 20 parts high-alumina admixture, 6 parts phosphogypsum, 4.5 parts sodium silicate, 2.0 parts sodium hydroxide, and 0.1 parts triisopropanolamine.

[0067] A method for preparing a copper slag-based cementitious material includes the following steps: (1) Dissolve 0.1 parts by weight of triisopropanolamine in 4 parts of anhydrous ethanol to prepare an ethanol solution of triisopropanolamine; pour copper slag, sodium silicate, and sodium hydroxide into a ball mill, spray the above-mentioned ethanol solution of triisopropanolamine into it, and grind them together for 50 min to obtain a specific surface area of ​​510 m². 2 / kg of finely ground copper slag composite powder; (2) The high-alumina admixture is premixed with phosphogypsum to obtain a premixed material. The premixed material is then mixed evenly with the finely ground copper slag composite powder obtained in step (1) to obtain copper slag-based cementitious material D5.

[0068] Comparative Example 6 (without co-grinding step) A copper slag-based cementitious material, identical to that in Example 1.

[0069] A method for preparing a copper slag-based cementitious material includes the following steps: Copper slag, calcium oxide, high-alumina admixtures, and phosphogypsum were mixed in one step and then ground to a similar specific surface area of ​​515 m². 2 / kg, and while stirring, add the ethanol solution of triisopropanolamine and dipotassium hydrogen phosphate in sequence, mix well, and you will get copper slag-based cementitious material D6.

[0070] Comparative Example 7 (Ordinary Portland Cement Control) PO 42.5 ordinary Portland cement (purchased from Sichuan Esheng Cement Group Co., Ltd.) was used as the cementing material, denoted as D7.

[0071] Technical effects: In accordance with the requirements of the Technical Specification for Tailings Paste Backfill (GB / T 39489-2020), the cementitious materials obtained from all examples and comparative examples were mixed with the aforementioned gold mine tailings with an arsenic content of 550 mg / kg and a ash-to-sand ratio of 1:8 and a mass concentration of 65% (representing a range of 64%-66%) to prepare backfill slurry. The slump and mechanical properties of the slurry were then tested.

[0072] After the slurry was thoroughly mixed, its slump was tested first, and then it was poured into a 70.7mm×70.7mm×70.7mm mold, compacted, and smoothed. The specimens were cured in a standard curing chamber at a temperature of 20±2℃ and a humidity of ≥95% for 72 hours, after which they were demolded and continued to be cured until the specified age.

[0073] Mechanical property testing: Unconfined compressive strength was tested at 7d, 14d and 28d respectively.

[0074] Environmental safety testing: The 28-day-old specimens were crushed and ground, and the leaching toxicity of heavy metal arsenic (As) was tested in accordance with the "Leaching Toxicity of Solid Waste - Horizontal Oscillation Method" (HJ 557-2010).

[0075] The results are summarized in Table 3.

[0076] Table 3. Performance test results of copper slag-based cementitious materials used in each embodiment and comparative example. As shown in Table 3, Examples 1-3 demonstrate the excellent performance under the core formulation of this invention. Example 4 shows that copper slag from different sources can all yield cementitious materials with satisfactory performance after being treated by the method of this invention, proving the universality of the technology. Examples 5-7 show that by adjusting the formulation within the weight range of each raw material in this invention, qualified filling materials with a 28-day compressive strength of about 3.0 MPa can be obtained. In particular, Examples 6 and 7 demonstrate the effective boundaries of the formulation.

[0077] Comparative Examples 1 (D1) and 2 (D2) lacked calcium oxide and dipotassium hydrogen phosphate, respectively, resulting in a significant decrease in both strength and arsenic curing effect, demonstrating the crucial synergistic effect of calcium oxide and dipotassium hydrogen phosphate. Specifically, Comparative Example 2 (D2) completely lacked dipotassium hydrogen phosphate, exhibiting a strength of only 1.08 MPa (far lower than the examples) and an arsenic leaching concentration as high as 556.0 μg / L. This strongly demonstrates the indispensable role of phosphate (dipotassium hydrogen phosphate) in forming the strength framework (phosphate gel) and curing arsenic in this invention.

[0078] Comparative Example 3 (D3), lacking triisopropanolamine, exhibited significantly inferior 28-day strength (1.46 MPa) and arsenic leaching concentration (268.5 μg / L) compared to the embodiments of the present invention. Triisopropanolamine plays a role in chelating Fe in this system. 2+ It plays a key role in accelerating ion dissolution (increasing the dissolution rate by >40%). The lack of this component leads to a decrease in the activation efficiency of fir olivine, which in turn affects the rate and extent of phosphate gel formation, indicating that it is irreplaceable in the synergistic activation pathway of this invention.

[0079] Comparative Example 4 (D4) lacked phosphogypsum, resulting in a significant decrease in its 28-day strength (1.55 MPa) and arsenic curing effect (240.8 μg / L). Phosphogypsum provides both calcium and sulfur sources in this system and is an essential raw material for the formation of ettringite (AFt). The absence of phosphogypsum prevents the formation of the composite structure of "phosphate framework + ettringite filler," leading to insufficient pore filling and decreased structural density, thus affecting overall performance and environmental safety.

[0080] Comparative Example 5 (D5) completely replaced the calcium oxide-dipotassium hydrogen phosphate system of the present invention with a conventional alkaline activator (sodium silicate + sodium hydroxide). While its strength (1.69 MPa) was superior to that of D4 without phosphate, it was far lower than that of the embodiments of the present invention, and its arsenic curing effect (247.4 μg / L) was also poor. This demonstrates that conventional alkaline activators cannot achieve the synergistic activation and efficient arsenic stabilization effects of the present invention.

[0081] Comparative Example 6 (D6) modified the preparation process by eliminating the co-grinding step of copper slag and calcium oxide. Its strength (1.61 MPa) decreased significantly, indicating that the specific step of "spraying triisopropanolamine solution into copper slag and calcium oxide and co-grinding" is crucial for achieving Fe... 2+ Efficient dissolution and early activation are crucial, and simple mixing and grinding cannot achieve the same effect.

[0082] Comparative Example 7 (D7) used ordinary Portland cement, and its strength (0.63 MPa) and arsenic curing effect (576.5 μg / L) were the worst, indicating that traditional cement does not have advantages in low admixture, fine-grained tailings and arsenic curing.

[0083] In summary, the calcium oxide-phosphate synergistic activation system and corresponding preparation method provided by this invention are efficient and essential for preparing high-performance backfill cementitious materials from copper slag with extremely low activity. This system is not only effective within a wide range of raw material ratios and sources, but more importantly, its unique phosphate-ettling stone composite structure endows the material with superior arsenic solidification capabilities—a characteristic unmatched by traditional cement or alkali-activated systems. This invention provides an innovative and reliable all-solid-waste solution for the safe and economical backfilling of arsenic-containing tailings from gold mines and other similar sites.

[0084] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A copper slag-based cementitious material synergistically activated by calcium oxide and phosphate, characterized in that, The ingredients include the following parts by weight: The ingredients are: 60-80 parts copper slag, 15-30 parts high-alumina admixture, 5-10 parts phosphogypsum, 3-8 parts calcium oxide, 4-12 parts dipotassium hydrogen phosphate, and 0.05-0.3 parts triisopropanolamine.

2. The copper slag-based cementitious material synergistically activated by calcium oxide and phosphate according to claim 1, characterized in that, The mass fraction of Al2O3 in the high-alumina admixture is ≥30%.

3. The copper slag-based cementitious material synergistically activated by calcium oxide and phosphate according to claim 1, characterized in that, The high-alumina admixture includes one or more of fly ash, red mud, and coal gangue.

4. A method for preparing a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate as described in any one of claims 1-3, characterized in that, Includes the following steps: An ethanol solution of triisopropanolamine was sprayed into copper slag and calcium oxide, and then ground to obtain fine copper slag composite powder. Take high-alumina admixture and phosphogypsum, mix them evenly with the finely ground copper slag composite powder, add dipotassium hydrogen phosphate, seal and stir to obtain the copper slag-based cementitious material.

5. The preparation method of a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate according to claim 4, characterized in that, The grinding process involves grinding to a specific surface area ≥ 450m². 2 / kg.

6. The application of a copper slag-based cementitious material synergistically activated by calcium oxide and phosphate as described in any one of claims 1-3 in mine backfilling.

7. A mine backfill slurry, characterized in that, The raw materials include: copper slag-based cementitious material as described in any one of claims 1-3, gold mine tailings and water; wherein the mass ratio of the copper slag-based cementitious material to the gold mine tailings is 1:8, and the mass concentration of the filling slurry is 64-66%.

8. The mine backfill slurry according to claim 7, characterized in that, The slump of the mine filling grout is 210-240 mm.

9. A method for preparing mine backfill slurry as described in any one of claims 7-8, characterized in that, The copper slag-based cementitious material, gold mine tailings, and water are mixed according to the mass ratio and stirred until a homogeneous slurry is obtained, which is the mine filling slurry.

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