Gold tailing-based concrete recycled aggregate and preparation method thereof

Abstract

The invention relates to a method for preparing concrete recycled aggregate from gold tailing sand, which comprises the following steps of: firstly, pouring the gold tailing sand into a turntable balling mill, and spraying water on the tailing sand to fully wet the surface of the tailing sand; when tailing sand microspheres appear, cementitious materials such as cement, coal ash, mineral powder and silica fume are slowly scattered, and meanwhile, an active exciting agent is sprayed; continuously repeating the operation until the gold tailing sand particles are completely formed; and finally, putting the recycled aggregate into a concrete standard curing chamber, a carbonization box or a steam curing box, and curing for 7-14 days to obtain the gold tailing sand recycled aggregate. The preparation method is simple and feasible in process, the consumption of natural ore can be saved, preparation and application of the low-carbon cement-based material are assisted, the utilization level and high additional value of the gold tailing sand can be improved, and resource recycling of the gold tailing sand in the field of building materials is achieved.

Description

Technical Field

[0001] This invention relates to a method for preparing recycled aggregate for concrete using gold tailings sand, belonging to the field of manufactured sand and gravel building materials. Background Technology

[0002] Gold tailings are a type of solid waste generated during gold mining, primarily composed of silicon dioxide, alumina, calcium oxide, iron oxide, and small amounts of alkaline oxides. Due to its low fineness modulus, it is unsuitable for use as fine aggregate in concrete. Traditional treatment methods mainly involve stockpiling, but tailings dams not only occupy large amounts of land but also easily generate dust and leaks, causing serious pollution to the atmosphere, water bodies, and soil. Therefore, how to economically and effectively treat gold tailings harmlessly and achieve large-scale utilization of this type of solid waste has become a research hotspot in environmental governance and sustainable development of building materials.

[0003] Because gold tailings contain over 80% inorganic minerals such as silicon and aluminum oxides, they have begun to be used as alternative raw materials for functional building materials, including gold tailings bricks, cement, concrete, microcrystalline glass, ceramsite, and ceramics, with some success. Gold tailings contain a large amount of aluminosilicates and a small amount of trace components, similar to the composition of traditional brick-making clay. By appropriately controlling the proportions of tailings and other additives, sintered bricks with various properties can be obtained. However, in actual production, sintered bricks made with gold tailings require high energy and heat consumption, and regular maintenance of kilns leads to high costs and low product efficiency, limiting the development of sintered bricks. Furthermore, due to the small particle size and large specific surface area of ​​gold tailings sand, a large dosage when used as concrete aggregate will significantly increase the water demand of the concrete mix, potentially causing bleeding and affecting concrete strength.

[0004] This invention uses gold tailings sand, mineral powder, fly ash and other solid wastes, as well as active activators, as the main raw materials. It utilizes rotary ball forming technology to produce high-performance recycled concrete aggregates, achieving the purpose of co-processing and utilizing bulk solid wastes such as tailings, fly ash and slag. It has significant social, economic and environmental benefits, and can also alleviate the growing shortage of usable resources in the building materials industry. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing concrete aggregate using gold tailings, which can solve the problems of long-term accumulation and environmental pollution caused by gold tailings. The recycled aggregate prepared by this invention has a density of 2220~3420 kg / m³. 3 The aggregate has a particle size of 2.5-30mm, a crushing value of less than 5%, and a water absorption rate of less than 4%. It has the advantages of simple preparation process, low cost, and high economic benefits, and is convenient for the disposal of bulk solid waste such as gold tailings and industrial applications.

[0006] To achieve the above objectives, the present invention employs the following process:

[0007] S1: First, mix cement, fly ash, mineral powder, silica fume and other materials in a certain proportion, and use a mixer to mix them evenly to obtain cementitious materials.

[0008] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0009] S3: The formed gold tailings-based aggregate is placed in a standard curing box, carbonization box or steam curing box for curing to prepare gold tailings-based recycled aggregate.

[0010] The cement mentioned in step S1 is 42.5 grade silicate cement. The cement content in the cementitious material is 70-85%, the fly ash content is 5-15%, the mineral powder content is 5-10%, and the silica fume content is 2-5%. The chemical composition of the cementitious material and the gold tailings sand is shown in Table 1.

[0011] Table 1 Chemical composition of raw materials <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO <![CDATA[Na2O]]> <![CDATA[K2O]]> <![CDATA[SO3]]> other cement 20.58 63.57 4.97 3.58 2.29 0.53 0.66 2.00 1.82 fly ash 48.25 7.38 27.68 7.67 0.91 0.83 1.22 1.44 4.62 Mineral powder 26.10 33.60 13.80 14.10 8.10 0.45 0.81 0.02 3.02 silica ash 94.92 2.29 0.72 0.65 0.55 0.48 0.31 0.03 0.05 Gold tailings 70.30 1.79 16.30 1.57 0.72 3.04 5.48 0.30 0.50

[0012] The activator mentioned in step S2 is triethanolamine, sodium sulfate, calcium formate, and calcium chloride. The activator needs to be prepared as an aqueous solution in advance. The dosage of sodium sulfate, calcium formate, and calcium chloride is 2% of the cementitious material, and the dosage of triethanolamine is 0.05% of the cementitious material. The total amount of the activator solution added is 20% to 40% of the cementitious material. The main function of the activator is to improve the early reactivity of cementitious materials such as cement clinker, fly ash, and mineral powder.

[0013] The mass ratio of the cementitious material to the gold tailings sand mentioned in step S2 is called the cement-sand ratio, which ranges from 0.5 to 2.0.

[0014] The standard curing temperature in step S3 is 20℃ and the humidity is 95%, the carbonization curing temperature is 20℃ and the humidity is 85% and the CO2 concentration is 20%, the steam curing temperature is 60℃, and the curing time is 7~14 days.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. A method for preparing recycled concrete aggregate using solid waste materials such as gold tailings sand, fly ash, and mineral powder as raw materials was proposed. This method not only solves the disposal and pollution problems of various solid wastes, but also realizes the reuse of tailings resources and reduces the amount of natural sand and gravel used.

[0017] 2. The prepared gold tailings-based recycled aggregate has excellent performance and broad application prospects. It can be used in construction projects such as buildings and roads, and has good economic and social benefits. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0019] Example 1

[0020] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 85:8:5:2, and use a mixer to mix them evenly to obtain a cementitious material.

[0021] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0022] S3: Place the formed gold tailings-based aggregate into a standard curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G1.

[0023] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 5%, and the amount added is 40% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 2.0.

[0024] Example 2

[0025] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 85:8:5:2, and use a mixer to mix them evenly to obtain a cementitious material.

[0026] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0027] S3: Place the formed gold tailings-based aggregate into a standard curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G2.

[0028] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 6.67%, and the addition amount is 30% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.5.

[0029] Example 3

[0030] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 85:8:5:2, and use a mixer to mix them evenly to obtain a cementitious material.

[0031] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0032] S3: Place the formed gold tailings-based aggregate into a standard curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G3.

[0033] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0034] Example 4

[0035] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 85:8:5:2, and use a mixer to mix them evenly to obtain a cementitious material.

[0036] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0037] S3: Place the formed gold tailings-based aggregate into a standard curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G4.

[0038] The active activator is sodium sulfate, the sodium sulfate solution concentration is 10%, and the addition amount is 20% of the cementitious material; the mass ratio of the cementitious material to the gold tailings sand is 0.5.

[0039] Example 5

[0040] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 80:10:5:5, and use a mixer to mix them evenly to obtain a cementitious material.

[0041] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0042] S3: Place the formed gold tailings-based aggregate into a standard curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G5.

[0043] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0044] Example 6

[0045] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 80:10:5:5, and use a mixer to mix them evenly to obtain a cementitious material.

[0046] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0047] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G6.

[0048] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0049] Example 7

[0050] S1: First, mix cement, fly ash, mineral powder, and silica fume in a ratio of 80:10:5:5, and use a mixer to mix them evenly to obtain a cementitious material.

[0051] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0052] S3: Place the formed gold tailings-based aggregate into a steam curing chamber and cure for 7 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G7.

[0053] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0054] Example 8

[0055] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 80:10:5:5, and use a mixer to mix them evenly to obtain cementitious material.

[0056] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0057] S3: Place the formed gold tailings-based aggregate in a steam curing chamber for 3 days, then place it in a standard curing chamber for 11 days. Then, mix the various aggregate sizes prepared according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G8.

[0058] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0059] Example 9

[0060] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 75:10:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0061] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0062] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G9.

[0063] The active activator is sodium sulfate, the concentration of sodium sulfate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0064] Example 10

[0065] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 75:10:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0066] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0067] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G10.

[0068] The active activator is calcium formate, the concentration of calcium formate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.0.

[0069] Example 11

[0070] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 75:10:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0071] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0072] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G11.

[0073] The active activator is calcium chloride, the concentration of the calcium chloride solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of the cementitious material to the gold tailings sand is 1.0.

[0074] Example 12

[0075] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 75:10:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0076] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0077] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G12.

[0078] The active activator is triethanolamine, the concentration of the triethanolamine solution is 0.2%, and the addition amount is 25% of the cementitious material; the mass ratio of the cementitious material to the gold tailings sand is 1.0.

[0079] Example 13

[0080] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 70:15:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0081] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0082] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G13.

[0083] The active activator is triethanolamine, the concentration of the triethanolamine solution is 0.2%, and the addition amount is 25% of the cementitious material; the mass ratio of the cementitious material to the gold tailings sand is 1.5.

[0084] Example 14

[0085] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 70:15:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0086] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0087] S3: Place the formed gold tailings-based aggregate into a steam curing chamber and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G14.

[0088] The active activator is triethanolamine, the concentration of the triethanolamine solution is 0.2%, and the addition amount is 25% of the cementitious material; the mass ratio of the cementitious material to the gold tailings sand is 1.5.

[0089] Example 15

[0090] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 70:15:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0091] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0092] S3: Place the formed gold tailings-based aggregate into a steam curing chamber and cure for 7 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G15.

[0093] The active activator is calcium formate, the concentration of calcium formate solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.5.

[0094] Example 16

[0095] S1: First, mix cement, fly ash, mineral powder and silica fume in a ratio of 70:15:10:5, and use a mixer to mix them evenly to obtain cementitious material.

[0096] S2: Add an appropriate amount of gold tailings sand to the rotary pelletizer. During rotation, spray an active activator to completely wet its surface. As the sand gradually agglomerates into granular material, add some cementitious material. At this point, the material will adsorb the cementitious material to form larger spherical materials as the pelletizing core. Subsequently, continue spraying the active activator and adding cementitious material. The water film on the surface of the microspheres continuously absorbs water and coats the cementitious material, causing the microspheres to gradually grow larger. Repeat this process continuously until the desired gold tailings-based spherical aggregate is formed.

[0097] S3: Place the formed gold tailings-based aggregate into a carbonization curing box and cure for 14 days. Then, mix the various aggregates of different particle sizes evenly according to the gradation requirements of "Construction Pebbles and Crushed Stones" (GB / T 14685~2022) to obtain 5~20mm gold tailings-based recycled aggregate G16.

[0098] Among them: the active activator is calcium chloride, the concentration of calcium chloride solution is 8%, and the addition amount is 25% of the cementitious material; the mass ratio of cementitious material to gold tailings sand is 1.5.

[0099] The recycled aggregates prepared in Examples 1-16 were tested for their crushing value, water absorption rate, and apparent density according to the "Construction Gravel and Crushed Stone" standard (GB / T 14685~2022). The test results are shown in Table 2. Concrete was prepared using a commonly used C30 ready-mixed concrete mix design. The mix design, properties, and strength of the concrete mixture are shown in Table 3.

[0100] Table 2 Crushing value, moisture content and apparent density of recycled aggregate Recycled aggregate Crushing value / % Water absorption rate / % <![CDATA[Apparent density / kg / m 3 > G1 3.17 2.83 2626.7 G2 3.71 2.43 2547.4 G3 4.21 2.70 2580.8 G4 4.58 3.27 2736.6 G5 5.21 1.76 2465.2 G6 4.20 2.39 2632.0 G7 4.41 2.55 2699.6 G8 3.95 2.27 2580.7 G9 3.29 2.52 2928.7 G10 4.54 2.13 2504.8 G11 4.00 1.46 2558.0 G12 3.11 1.99 2493.4 G13 3.41 2.72 2687.6 G14 3.65 2.6 2580.5 G15 2.96 2.45 2728.3 G16 3.54 1.86 2503.4 limestone gravel 16.4 1.21 2700.0 Granite Crushed Stone 13.2 1.08 2740.0

[0101] Table 3. Mix proportions and performance test results of C30 ready-mixed concrete

[0102] As shown in Tables 2 and 3, the recycled aggregate prepared by the present invention using gold tailings sand, fly ash, slag and other solid waste materials has performance comparable to that of natural crushed stone. It can be used in the field of ordinary ready-mixed concrete for construction projects such as buildings and roads, and achieves the purpose of co-processing and utilizing bulk solid wastes such as tailings, fly ash and slag. It has good promotion and utilization value.

Claims

1. A recycled aggregate for gold tailings-based concrete and its preparation method, characterized in that, Includes the following steps: S1: Cement, fly ash, mineral powder, silica fume and other materials are mixed in a certain proportion and mixed evenly using a mixer to obtain a cementitious material; S2: Add an appropriate amount of gold tailings sand to the rotary baller and spray an active activator to completely wet its surface; when the sand gradually agglomerates to form granular material, gradually add cementitious material and continue to spray an active activator until 5-20mm gold tailings-based spherical aggregate is formed. S3: Place the formed gold tailings-based aggregate into a standard curing box, carbonization box, or steam curing box and cure for 7-14 days to prepare gold tailings-based recycled aggregate.

2. The recycled aggregate for gold tailings-based concrete and its preparation method according to claim 1, characterized in that, The cement is grade 42.5 silicate cement, and the cement content in the cementitious material is 70-85%, fly ash content is 5-15%, mineral powder content is 5-10%, and silica fume content is 2-5%.

3. The recycled aggregate for gold tailings-based concrete and its preparation method according to claim 1, characterized in that, The gold tailings sand has a particle size range of 0-5mm and a fineness modulus of 2.8-3.

0.

4. The recycled aggregate for gold tailings-based concrete and its preparation method according to claim 1, characterized in that, The active activator is triethanolamine, sodium sulfate, calcium formate and calcium chloride. The active activator needs to be prepared into an aqueous solution in advance. The amount of sodium sulfate, calcium formate and calcium chloride is 2% of the cementitious material, the amount of triethanolamine is 0.05% of the cementitious material, and the total amount of active activator solution added is 20% to 40% of the cementitious material.

5. The recycled aggregate for gold tailings-based concrete and its preparation method according to claim 1, characterized in that, The mass ratio of the cementitious material to the gold tailings sand is called the cement-sand ratio, which ranges from 0.5 to 2.

0.

6. The recycled aggregate for gold tailings-based concrete and its preparation method according to claim 1, characterized in that, The standard curing temperature is 20℃ and the humidity is 95%, the carbonization curing temperature is 20℃ and the humidity is 85% and the CO2 concentration is 20%, the steam curing temperature is 60℃, and the curing time is 7~14 days.

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