Roadbed filler based on high-water-content gold flotation tailings and preparation method thereof

Abstract

The invention relates to the technical field of roadbed engineering, in particular to roadbed filler based on high-water-content gold flotation tailings and a preparation method of the roadbed filler. The roadbed filler comprises the following raw materials: the gold flotation tailings, a modified precipitation material, a curing agent, an exciting agent, a solid modifier and an anti-cracking agent, wherein the moisture content of the gold flotation tailings is lower than 20%; according to the invention, the gold flotation tailings with high water content are subjected to pre-dehydration treatment and efficient curing treatment by adopting the porous precipitation material and the low-carbon cementing material, so that the roadbed filler with low carbon, low cost, high strength and low shrinkage is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed engineering, and in particular to a roadbed filler based on high-water-content gold flotation tailings and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] With the rapid development of highway engineering construction, there is a huge demand for natural filling materials such as soil and stone in roadbed filling. The traditional mode of taking soil to build roads has caused serious damage to natural resources and the environment. Therefore, alternative roadbed filling materials are urgently needed.

[0004] Gold tailings are solid wastes discharged after gold ores are beneficiated or gold-extracted to recover gold or other useful components. They are usually divided into gold flotation tailings and cyanide tailings. Gold flotation tailings are tailings produced simultaneously when gold concentrate is selected by flotation after the ore is crushed and ground. They are general solid wastes and account for more than 97% of the total amount of gold tailings. Gold flotation tailings contain more than 80% of inorganic minerals such as silicon aluminum oxides, and their composition is close to the raw material composition of many building materials products. Therefore, in theory, gold flotation tailings can be used to prepare engineering materials. However, its high water content makes it easy to liquefy and lack strength when directly filled, and the single physical dehydration process (such as drying and filter pressing) consumes a lot of energy and has a long cycle, so it cannot be directly used for engineering materials on a large scale.

[0005] At present, attempts are being made to use gold flotation tailings for roadbed filling, but traditional solidifying agents (such as cement) have significant defects: on the one hand, cement production has high carbon emissions (about 0.8 tons of CO2 are emitted per ton of cement); on the other hand, cement solidification of gold tailings is easily disturbed by high water content, and the gelling reaction is insufficient, resulting in low strength and poor durability of the solidified body. It is necessary to add 10% to 20% cement or composite solidifying agent to meet the roadbed requirements, and the economy and sustainability are limited. Summary of the invention

[0006] In order to overcome the above problems, the present invention provides a roadbed filler based on high-water-content gold flotation tailings and a preparation method thereof.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: The first aspect of the present invention provides a roadbed filler based on high-water-content gold flotation tailings, the raw materials of which include, by weight: 100 - 150 parts of gold flotation tailings, 20 - 30 parts of modified water-precipitating material, 5 - 10 parts of curing agent, 0.5 - 2 parts of activator, 0.1 - 0.5 parts of solid modifier, 0.1 - 0.2 parts of crack inhibitor; Among them, the water content of the gold flotation tailings is less than 20%; The modified water-precipitating material is obtained by modifying the water-precipitating material with the first modifier; the first modifier includes phosphoric acid, sodium silicate and graphene oxide; the water-precipitating material is selected from one or more of cinder, coal gangue, blast furnace slag and recycled aggregate; The curing agent includes slag, coal gasification slag powder, steel slag powder, incinerated garbage and gypsum; The activator includes carbide slag, sodium sulfate and red mud; The solid modifier includes carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate; The crack inhibitor includes waste tire rubber powder and recycled fiber.

[0008] In one or more embodiments, the particle size of the gold flotation tailings is less than 15 mm. There are two reasons for this particle size limitation: on the one hand, the filler particle size below 40 cm of the subgrade surface of expressways / first-class highways is required to be no more than 15 mm; on the other hand, large particle sizes are inconvenient for construction.

[0009] In one or more embodiments, the particle size of the water-precipitating material is less than 5 mm and the water absorption rate is greater than 5%. The limitation of the small particle size (<5 mm) is to allow the water-precipitating material to enter the interior of the gold flotation tailings and be evenly distributed; the high water absorption rate (>5%) is to enable it to adsorb the free water in the gold flotation tailings.

[0010] In one or more embodiments, in the first modifier, the concentration (mass fraction) of phosphoric acid is 6 - 10%, preferably 8%.

[0011] In one or more embodiments, in the first modifier, the oxygen content of graphene oxide is 24 - 30%, preferably 25%; the thickness is 0.8 - 2 nm, preferably 1 nm. The limitation of the oxygen content of graphene oxide can achieve a balance between "chemical activity - structural integrity", ensuring that graphene oxide can serve as a reaction platform while retaining its functionalization potential; the limitation of the thickness is to maintain the ultimate mechanical and transport properties of the nanosheets and avoid performance degradation caused by stacking.

[0012] In one or more embodiments, in the first modifier, the mass ratio of sodium silicate to graphene oxide is (1 to 1.5):1. Sodium silicate forms a -Si-O-Si- three-dimensional network in water, encapsulating the graphene oxide sheets, thereby enhancing the mechanical strength. If the ratio of the two is too low (<1:1), problems such as a sparse gel network, easy fragmentation of the composite material, and insufficient mechanical properties will occur. If the ratio of the two is too high (>1.5:1), problems such as excessive gel covering the surface of GO, shielding its functionality (such as conductivity, adsorption sites), too high rigidity of the material, and decreased toughness will occur.

[0013] In one or more embodiments, the method for preparing the modified precipitation material includes the following steps: Immerse the precipitation material in a phosphoric acid solution for pickling, take it out, wash it with water until neutral, and obtain the pretreated precipitation material after drying; Disperse sodium silicate in water to obtain an aqueous sodium silicate solution; then add graphene oxide, and after sufficient dispersion, obtain a modified aqueous sodium silicate solution; Immerse the pretreated precipitation material in the modified aqueous sodium silicate solution, take it out, and obtain the modified precipitation material after drying.

[0014] Preferably, during the pickling process, the treatment time is 20 to 30 min, and the treatment temperature is 40 to 60 °C.

[0015] Preferably, immerse the pretreated precipitation material in the modified aqueous sodium silicate solution and perform ultrasonic treatment for 15 to 30 min.

[0016] Preferably, the concentration (mass fraction) of sodium silicate in the aqueous sodium silicate solution is 8 to 12%, preferably 10%.

[0017] Preferably, the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution is (10 to 12):1.

[0018] Under the above-defined conditions, the pretreated precipitation material can fully contact the modified aqueous sodium silicate solution, thereby completing the modification.

[0019] In one or more embodiments, in the curing agent, the mass ratio of slag, coal gasification slag powder, steel slag powder, incinerated garbage, and gypsum is (25 to 50):(15 to 30):(10 to 30):(15 to 25):(5 to 15).

[0020] In one or more embodiments, the slag in the curing agent is of S95 grade or above, and the content of SiO2 and CaO is greater than 75%.

[0021] In one or more embodiments, in the curing agent, the content of SiO2 + CaO + Al2O3 in the coal gasification slag powder is greater than 80%.

[0022] In one or more embodiments, in the curing agent, the content of SiO2 + Al2O3 in the incinerated garbage is greater than 50%.

[0023] In one or more embodiments, in the curing agent, the gypsum is selected from one or more of titanium gypsum, phosphogypsum, or fluorogypsum.

[0024] In one or more embodiments, in the activator, the mass ratio of carbide slag, sodium sulfate, and red mud is (5 - 10):(1 - 2):(5 - 10).

[0025] In one or more embodiments, in the activator, the content of Ca(OH)2 in the carbide slag is greater than 65%.

[0026] In one or more embodiments, in the activator, the pH of the red mud is greater than 12.

[0027] In one or more embodiments, in the solid modifier, the mass ratio of carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate is (1 - 2):(0.5 - 1):(2 - 3):(3 - 5).

[0028] In one or more embodiments, in the solid modifier, the calcium sulfoaluminate is a white powder with a specific surface area ≥ 400m 2 / kg.

[0029] In one or more embodiments, in the crack resistance agent, the mass ratio of waste tire rubber powder and recycled fiber is (5 - 10):(1 - 3).

[0030] In one or more embodiments, the particle size of the waste tire rubber powder is less than 0.5 mm. Limiting the particle size of the waste tire rubber powder in the highway subgrade filling material to less than 0.5 mm is because: this size is the critical threshold for the rubber powder to change from a "discrete admixture" to a "functionalized soil component", and exceeding this limit will lead to a systematic deterioration of engineering performance; by size constraint, the microscopic scale fusion of the concrete matrix and the rubber addition phase is realized, so that the waste tire is transformed from an environmental burden into a high-value subgrade improvement material.

[0031] In one or more embodiments, the recycled fiber is sourced from waste fishing nets, industrial non-woven fabrics, and waste yachts; the particle size of the recycled fiber is 2 - 5 mm. This condition is limited to the critical size for the waste fiber to transform from a "physical admixture" to an "intelligent crack resistance skeleton", achieving the contradiction between strength requirements, ecological risks, and engineering efficiency with millimeter-level precision.

[0032] The second aspect of the present invention provides a method for preparing the subgrade filler based on high-water-content gold flotation tailings described in the first aspect, including the following steps: (1) Mix the gold flotation tailings and the modified precipitation material evenly to obtain the first mixture; (2) Ball mill the curing agent and the activator to obtain the second mixture; (3) Mix the first mixture, the second mixture, the solid modifier and the crack inhibitor evenly, form, and cure to obtain the subgrade filler based on high-water-content gold flotation tailings.

[0033] In one or more embodiments, in step (1), mixing is carried out by stirring, the stirring rate is 25-35 r / min, and the stirring time is 10-20 min.

[0034] In one or more embodiments, in step (2), the rotational speed of the ball milling is 400-500 r / min, the ball milling time is 2-3 min, and the specific surface area of the second mixture after ball milling is greater than 450 m 2 / kg.

[0035] The beneficial effects of the present invention are as follows: (1) In the present invention, porous precipitation materials and low-carbon cementitious materials are used to perform pre-dehydration treatment and efficient solidification treatment on high-water-content gold flotation tailings, and a subgrade filler with low carbon, low cost, high strength and low shrinkage is obtained. The precipitation material is modified by the first modifier to obtain a porous modified precipitation material. Specifically: the carbonate impurities, metal oxides and some silicate pollutants in the pores of the precipitation material are dissolved by phosphoric acid solution to dredge the pores; the precipitation material is impregnated with sodium silicate solution and graphene oxide to form a hydrophilic coating, and the high specific surface area and hydrophilic characteristics of graphene oxide are used to enhance water absorption to form a microscopic water storage network; the porous precipitation material quickly adsorbs the free water in the gold flotation tailings, reducing the water content of the gold flotation tailings to the optimal water content. The free water adsorbed by the porous precipitation material can provide sufficient water for the later hydration reaction of the low-carbon cementitious material, acting as a water storage tank and effectively preventing the subgrade filler from cracking and shrinking later; using slag, coal gasification slag powder, steel slag powder, incinerated garbage, gypsum and activator as low-carbon cementitious materials, where slag, coal gasification slag powder, and incinerated garbage provide CaO, SiO2 and Al2O3 to form C-S-H and C-A-S-H gels during the hydration process, which are the main strength sources of the cementitious material. The high alkalinity (pH>12) of the steel slag powder can promote the dissolution of the active Si / Al of the coal gasification slag powder, and at the same time the SO4 provided by the gypsum 2- with Al 3+The reaction generates ettringite, forming an intertwined network structure to improve the mechanical strength. The activator can increase the alkalinity of the system, promote the breaking of Si-O and Al-O bonds in slag and steel slag, and accelerate the hydration reaction. The hydroxyl groups (-OH) and carboxyl groups (-COOH) in the carboxymethyl cellulose molecular chain can form hydrogen bonds with hydration products (such as C-S-H gel), improving the density of the microstructure and further enhancing the curing effect of the curing agent. Calcium formate, sodium nitrite, and calcium sulfoaluminate synergistically accelerate the initial stage of the hydration reaction, promote the early formation of C-S-H gel and ettringite (AFt), and reduce the porosity through interface strengthening. The waste tire rubber powder and recycled fiber synergistically act through multiple paths of "elastic buffering - reinforcement enhancement - pore regulation", effectively solving the problem of insufficient strength of the high-water-content gold tailings subgrade filler.

[0036] (2) The subgrade filler provided by the present invention meets the strength requirements in the current "Code for Design of Highway Subgrade" (JTG D30), can effectively prevent subgrade cracking, and at the same time improves the frost and thaw resistance effect, extending the service life of the subgrade.

[0037] (3) The present invention uses multi-source solid wastes to completely replace cement to prepare a cementitious material based on flotation gold tailings, which can not only improve the strength of the mixture but also effectively solidify the harmful substances in the flotation gold tailings, facilitating the full utilization of bulk solid wastes. Detailed implementation manners

[0038] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments.

[0041] In the following embodiments, the chemical components of slag, coal gasification slag powder, steel slag powder, incinerated garbage, gypsum, carbide slag, red mud, and gold flotation tailings are shown in Table 1.

[0042] Table 1 Oxide content of raw materials

[0043] In the following examples, the water content of the gold flotation tailings is 18%, and the particle size is less than 13 mm.

[0044] The particle size of the precipitation material is less than 5 mm, and the water absorption rate is greater than 5%.

[0045] In the curing agent, the slag is above S95 grade; the steel slag powder is treated by high-temperature calcination or chemical activation, and the specific surface area ≥ 400 m 2 / kg, activity index: ≥ 65% in 7 days, ≥ 85% in 28 days.

[0046] In the activator, the purity of sodium sulfate ≥ 92%; the pH of the red mud is 12.7; In the solid modifier, the industrial purity of carboxymethyl cellulose ≥ 98%, and the water retention rate ≥ 95%; the industrial purity of calcium formate ≥ 95%; the industrial purity of sodium nitrite ≥ 96%; the specific surface area of calcium sulfoaluminate ≥ 400 m 2 / kg.

[0047] The recycled fiber is selected from waste fishing nets, and the particle size of the fiber is 3 mm.

[0048] The particle size of the waste tire rubber powder is less than 0.5 mm.

[0049] Example 1 The raw material formula of a subgrade filler based on high-water-content gold flotation tailings is shown in Table 2.

[0050] Table 2 Raw material formula (mass ratio)

[0051] In this example, the modified precipitation material is modified coal cinder; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated garbage and gypsum, and the mass ratio is 25:15:10:15:5; the activator is carbide slag, sodium sulfate and red mud, and the mass ratio is 10:2:10; the solid modifier is carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate, and the mass ratio is 1:0.5:2:3; the anti-cracking agent is waste tire rubber powder and recycled fiber, and the mass ratio is 10:3.

[0052] Among them, the preparation method of the modified precipitation material includes: Soak the precipitation material in a phosphoric acid solution with a concentration (mass fraction) of 8%. The mass ratio of the precipitation material to the phosphoric acid solution is 1:4. The pickling temperature is 40 °C and the time is 25 min. Take out the pickled precipitation material and wash it repeatedly with deionized water until neutral, and dry it in an oven at 105 °C for 6 h to obtain the pretreated precipitation material; Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1:1; after ultrasonic treatment for 25 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was immersed in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 10:1. After ultrasonic treatment for 20 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0053] Preparation of subgrade filler based on high-water-content gold flotation tailings: (1) Gold flotation tailings and the modified precipitation material were stirred in a large dry concrete mixer for 10 min at a rotation speed of 25 r / min to obtain a first mixture, which was reserved for later use. (2) The curing agent and the activator were ball-milled for 2 min at a rotation speed of 400 r / min to obtain a uniform second mixture with a specific surface area of 450 m 2 / kg, which was reserved for later use. (3) The first mixture, the second mixture, the solid modifier, and the anti-cracking agent were mixed evenly, formed, and cured to obtain a subgrade filler based on high-water-content gold flotation tailings.

[0054] Example 2 The raw material formula of a subgrade filler based on high-water-content gold flotation tailings is shown in Table 3.

[0055] Table 3 Raw material formula (mass part ratio)

[0056] In this example, the modified precipitation material was modified coal gangue; the curing agent was slag, coal gasification slag powder, steel slag powder, incinerated garbage, and gypsum, with a mass ratio of 35:30:20:25:15; the activator was carbide slag, sodium sulfate, and red mud, with a mass ratio of 5:2:5; the solid modifier was carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate, with a mass ratio of 2:0.8:3:5; the anti-cracking agent was waste tire rubber powder and recycled fiber, with a mass ratio of 5:1.

[0057] The preparation method of the modified precipitation material includes: The precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, and the mass ratio of the precipitation material to the phosphoric acid solution was 1:3. The pickling temperature was 60 °C, and the time was 30 min. The pickled precipitation material was taken out and washed repeatedly with deionized water until neutral, and then dried in an oven at 105 °C for 6 h to obtain the pretreated precipitation material. Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1.2:1; after ultrasonic treatment for 30 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was immersed in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 11:1. After ultrasonic treatment for 25 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0058] Preparation of subgrade filler based on high-water-content gold flotation tailings: (1) The gold flotation tailings and the modified precipitation material were stirred in a dry large concrete mixer for 20 min at a rotation speed of 35 r / min to obtain a first mixture, which was reserved for later use. (2) The curing agent and the activator were ball-milled for 3 min at a rotation speed of 500 r / min to obtain a uniform second mixture with a specific surface area of 550 m 2 / kg, which was reserved for later use. (3) The first mixture, the second mixture, the solid modifier, and the crack resistance agent were mixed evenly, formed, and cured to obtain a subgrade filler based on high-water-content gold flotation tailings.

[0059] Example 3 The raw material formula of a subgrade filler based on high-water-content gold flotation tailings is shown in Table 4.

[0060] Table 4 Raw material formula (mass part ratio)

[0061] In this example, the modified precipitation material was modified coal gangue; the curing agent was slag, coal gasification slag powder, steel slag powder, incinerated garbage, and gypsum, with a mass ratio of 50:30:30:25:10; the activator was carbide slag, sodium sulfate, and red mud, with a mass ratio of 8:1:5; the solid modifier was carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate, with a mass ratio of 2:1:3:4; the crack resistance agent was waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0062] The preparation method of the modified precipitation material includes: The precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, and the mass ratio of the precipitation material to the phosphoric acid solution was 1:5. The pickling temperature was 40 °C and the time was 20 min. After taking out the pickled precipitation material, it was repeatedly washed with deionized water until neutral and dried in an oven at 105 °C for 6 h to obtain the pretreated precipitation material. Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1:1; after ultrasonic treatment for 25 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was immersed in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 10:1. After ultrasonic treatment for 30 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0063] Preparation of a subgrade filler based on highly water - containing gold flotation tailings: (1) The gold flotation tailings and the modified precipitation material were stirred in a dry large - scale concrete mixer for 15 min at a rotation speed of 30 r / min to obtain a first mixture, which was reserved for later use. (2) The curing agent and the activator were ball - milled for 2 min at a rotation speed of 450 r / min to obtain a uniform second mixture with a specific surface area of 480 m 2 / kg, which was reserved for later use. (3) The first mixture, the second mixture, the solid modifier, and the crack inhibitor were mixed evenly, formed, and cured to obtain a subgrade filler based on highly water - containing gold flotation tailings.

[0064] Example 4 The raw material formula of a subgrade filler based on highly water - containing gold flotation tailings is shown in Table 5.

[0065] Table 5 Raw material formula (mass part ratio)

[0066] In this example, the modified precipitation material was modified coal gangue; the curing agent was slag, gasification slag powder, steel slag powder, incinerated garbage, and gypsum, with a mass ratio of 50:30:30:25:10; the activator was carbide slag, sodium sulfate, and red mud, with a mass ratio of 8:1:5; the solid modifier was carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate, with a mass ratio of 2:1:3:4; the crack inhibitor was waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0067] The preparation method of the modified precipitation material includes: The precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, and the mass ratio of the precipitation material to the phosphoric acid solution was 1:3. The temperature of the pickling was 60 °C, and the time was 25 min. After taking out the pickled precipitation material, it was repeatedly washed with deionized water until neutral and dried in an oven at 105 °C for 6 h to obtain the pretreated precipitation material. Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1.5:1; after ultrasonic treatment for 30 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was soaked in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 10:1. After ultrasonic treatment for 15 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0068] Preparation of subgrade filler based on highly water - containing gold flotation tailings: (1) The gold flotation tailings and the modified precipitation material were stirred in a large - scale dry concrete mixer for 10 min at a rotation speed of 35 r / min to obtain a first mixture, which was reserved for later use. (2) The curing agent and the activator were ball - milled for 3 min at a rotation speed of 400 r / min to obtain a uniform second mixture with a specific surface area of 520 m 2 / kg, which was reserved for later use. (3) The first mixture, the second mixture, the solid modifier, and the crack inhibitor were mixed evenly, formed, and cured to obtain the subgrade filler based on highly water - containing gold flotation tailings.

[0069] Example 5 The raw material formula of a subgrade filler based on highly water - containing gold flotation tailings is shown in Table 6.

[0070] Table 6 Raw material formula (mass part ratio)

[0071] In this example, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated garbage, and gypsum, with a mass ratio of 50:30:30:25:10; the activator is carbide slag, sodium sulfate, and red mud, with a mass ratio of 8:1:5; the solid modifier is carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate, with a mass ratio of 2:1:3:4; the crack inhibitor is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0072] Among them, the preparation method of the modified precipitation material includes: The precipitation material was soaked in a phosphoric acid solution with a concentration (mass fraction) of 8%, and the mass ratio of the precipitation material to the phosphoric acid solution was 1:5. The temperature of the acid pickling was 50 °C, and the time was 30 min. After taking out the pickled precipitation material, it was repeatedly washed with deionized water until neutral and dried in an oven at 105 °C for 6 h to obtain the pretreated precipitation material. Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1.2:1; after ultrasonic treatment for 25 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was soaked in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 12:1. After ultrasonic treatment for 30 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0073] Preparation of subgrade filler based on high-water-content gold flotation tailings: (1) The gold flotation tailings and the modified precipitation material were stirred in a large dry concrete mixer for 20 min at a rotation speed of 25 r / min to obtain a first mixture, which was reserved for later use. (2) The curing agent and the activator were ball-milled for 3 min at a rotation speed of 400 r / min to obtain a uniform second mixture with a specific surface area of 470 m 2 / kg, which was reserved for later use. (3) The first mixture, the second mixture, the solid modifier, and the crack inhibitor were mixed evenly, formed, and cured to obtain a subgrade filler based on high-water-content gold flotation tailings.

[0074] Example 6 The raw material formula of a subgrade filler based on high-water-content gold flotation tailings is shown in Table 7.

[0075] Table 7 Raw material formula (mass ratio)

[0076] In this example, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated garbage, and gypsum, with a mass ratio of 50:30:30:25:10; the activator is carbide slag, sodium sulfate, and red mud, with a mass ratio of 8:1:5; the solid modifier is carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate, with a mass ratio of 2:1:3:4; the crack inhibitor is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0077] The preparation method of the modified precipitation material includes: The precipitation material was soaked in a phosphoric acid solution with a concentration (mass fraction) of 8%, and the mass ratio of the precipitation material to the phosphoric acid solution was 1:4. The pickling temperature was 50 °C and the time was 30 min. After taking out the pickled precipitation material, it was repeatedly washed with deionized water until neutral and dried in an oven at 105 °C for 6 h to obtain the pretreated precipitation material. Sodium silicate was ultrasonically dispersed in water to obtain an aqueous sodium silicate solution with a concentration (mass fraction) of 10%; graphene oxide was added to the aqueous sodium silicate solution, and the mass ratio of sodium silicate to graphene oxide was 1.5:1; after ultrasonic treatment for 30 min, a modified aqueous sodium silicate solution was prepared. The pretreated precipitation material was immersed in the modified aqueous sodium silicate solution, and the mass ratio of the pretreated precipitation material to the modified aqueous sodium silicate solution was 10:1. After ultrasonic treatment for 20 min and drying (drying in an oven at 105 °C for 6 h), a modified precipitation material was obtained.

[0078] Preparation of subgrade filler based on high water content gold flotation tailings: (1) The gold flotation tailings and the modified precipitation material were stirred in a large dry concrete mixer for 18 min at a rotation speed of 25 r / min to obtain a first mixture, which was reserved for later use; (2) The curing agent and the activator were ball-milled for 3 min at a rotation speed of 480 r / min to obtain a uniform second mixture with a specific surface area of 490 m 2 / kg, which was reserved for later use; (3) The first mixture, the second mixture, the solid modifier and the crack inhibitor were mixed evenly, formed, and cured to obtain a subgrade filler based on high water content gold flotation tailings.

[0079] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw materials do not contain the modified precipitation material. Other methods and steps are the same as those in Example 1 and will not be repeated here.

[0080] Comparative Example 2 The difference between this comparative example and Example 1 is that the precipitation material in the raw materials was not modified. Other methods and steps are the same as those in Example 1 and will not be repeated here.

[0081] Comparative Example 3 The difference between this comparative example and Example 1 is that the curing agent and the activator in the raw materials are replaced by cement. Other methods and steps are the same as those in Example 1 and will not be repeated here.

[0082] Comparative Example 4 The difference between this comparative example and Example 1 is that the raw materials do not contain a crack inhibitor. Other methods and steps are the same as those in Example 1 and will not be repeated here.

[0083] Comparative Example 5 The difference between this comparative example and Example 1 is that the raw materials do not contain a solid modifier. Other methods and steps are the same as those in Example 1 and will not be repeated here.

[0084] Performance verification: According to the "Technical Specification for Highway Subgrade Construction" (JTG D30) and combined with the on-site use environment, the CBR tests and dry shrinkage tests of the subgrade filler specimens of high-water-content flotation gold tailings for Examples 1 to 6 and Comparative Examples 1 to 5 were carried out, and the test results are shown in Table 8.

[0085] Table 8 Test Results

[0086] It can be seen from Table 8 that the CBR values of the examples are all higher than those of the comparative examples, and are greater than 8% specified in the "Technical Specification for Highway Subgrade Construction" (JTG D30), while the CBR values of the comparative examples are all less than 8%; at the same time, the dry shrinkage strain and freeze-thaw mass loss in the examples are all less than those of the comparative examples, indicating that the performance of the subgrade filler prepared in the examples is better than that of the subgrade filler obtained in the comparative examples. From Examples 1 and Comparative Examples 1 to 5, it can be seen that the technical solution of the present invention significantly improves the performance of the subgrade filler through the triple action mechanism of porous precipitation material modification, solid waste-based cementitious system synergy, and functional additive strengthening. In Comparative Example 1 (without precipitation material), the mixture was in a too wet state and could not be formed because it could not adsorb free water; in Comparative Example 2 (unmodified precipitation material), due to pore blockage and poor surface hydrophilicity, the dehydration efficiency of gold tailings was poor and the CBR value did not meet the requirements; in Comparative Example 3 (cement replacing low-carbon cementitious material), the lack of the synergistic effect of the activities of multi-source industrial solid wastes made it impossible to form a relatively large network-like cementitious system in a water-rich environment; in Comparative Example 4 (without anti-cracking agent), the lack of the elastic sulfur bond network of rubber particles and the chemical bridging synergy on the fiber surface resulted in a large dry shrinkage strain; in Comparative Example 5 (without solid modifier), the early formation of C-S-H gel and ettringite (AFt) was reduced, the compactness of the microstructure was reduced, and the curing effect of the curing agent was further reduced. The advantages of Examples 1 to 6 are as follows: Pickling combined with sodium silicate and graphene oxide coating optimizes the pore water storage-release balance of the precipitation material. With the help of the multi-source industrial solid waste synergistic activation mechanism, the siliceous and aluminous components in the solid waste are dissociated to release active silicate and aluminate ions. Combined with the modifier and anti-cracking agent, the released active ions form chemical bridging with the elastic sulfur bond network of rubber particles and the fiber surface, and finally a "rigid-flexible combination" composite system is constructed at the microscopic level - it contains both the rigid skeleton of C-(A)-S-H gel and the embedded elastic rubber microphase and fiber-reinforced interface. The synergistic effect of this multi-level structure enables the material to achieve double performance breakthroughs of low shrinkage and freeze-thaw resistance. The lack of single components in the comparative examples all destroys this synergistic logic, verifying the systematicness and irreplaceability of the technical solution of the present invention.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A subgrade filler based on high water-content gold flotation tailings, characterized in that, The raw materials include by weight: 100-150 parts of gold flotation tailings, 20-30 parts of modified precipitation materials, 5-10 parts of curing agent, 0.5-2 parts of activator, 0.1-0.5 parts of solid modifier, 0.1-0.2 parts of anti-cracking agent; Among them, the moisture content of gold flotation tailings is less than 20%; The modified precipitation material is obtained by modifying the precipitation material with a first modifier; the first modifier includes phosphoric acid, sodium silicate and graphene oxide; the precipitation material is selected from one or more of coal slag, coal gangue, blast furnace slag and recycled aggregate; The curing agent includes slag, coal gasification slag powder, steel slag powder, incinerated garbage and gypsum; The activator includes carbide slag, sodium sulfate and red mud; The solid modifier includes carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate; The anti-cracking agent comprises waste tire rubber powder and recycled fiber.

2. The subgrade filler according to claim 1, characterized in that, The particle size of gold flotation tailings is less than 15 mm; The precipitation material has a particle size of less than 5 mm and a water absorption rate of greater than 5%.

3. The subgrade filler according to claim 1, characterized in that In the first modifier, the concentration of phosphoric acid is 6-10%; In the first modifier, the oxygen content of graphene oxide is 24-30%; the thickness is 0.8-2 nm; In the first modifier, the mass ratio of sodium silicate to graphene oxide is (1~1.5):

1.

4. The subgrade filler according to claim 1, wherein, The preparation method of the modified precipitation material comprises the following steps: The precipitation material is immersed in a phosphoric acid solution for pickling, taken out, washed with water until neutral, and dried to obtain a pretreated precipitation material; Dispersing sodium silicate in water to obtain a sodium silicate aqueous solution; then adding graphene oxide and fully dispersing it to obtain a modified sodium silicate aqueous solution; The pretreated precipitation material is immersed in a modified sodium silicate aqueous solution, taken out, and dried to obtain a modified precipitation material.

5. The subgrade filler according to claim 4, characterized in that, During the pickling process, the treatment time is 20~30min and the treatment temperature is 40~60℃; The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution and ultrasonically treated for 15-30 min; The concentration of sodium silicate in the sodium silicate aqueous solution is 8-12%; The mass ratio of the pretreated precipitation material to the modified sodium silicate aqueous solution is (10~12):

1.

6. The subgrade filler according to claim 1, wherein In the curing agent, the mass ratio of slag, coal gasification slag powder, steel slag powder, incinerated garbage and gypsum is (25-50): (15-30): (10-30): (15-25): (5-15); The slag in the curing agent is S95 grade or above, and the SiO2 and CaO content is greater than 75%; In the curing agent, the content of SiO2+CaO+Al2O3 in coal gasification slag powder is greater than 80%; In the curing agent, the content of SiO2+Al2O3 in the incinerated waste is greater than 50%; In the curing agent, the gypsum is selected from one or more of titanium gypsum, phosphogypsum and fluorgypsum.

7. The subgrade filler according to claim 1, wherein, In the activator, the mass ratio of carbide slag, sodium sulfate and red mud is (5~10): (1~2): (5~10); In the activator, the Ca(OH)2 content in the carbide slag is greater than 65%; In the activator, the pH of red mud is greater than 12.

8. The subgrade filler according to claim 1, characterized in that, In the solid modifier, the mass ratio of carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate is (1-2): (0.5-1): (2-3): (3-5); In the crack-resistant agent, the mass ratio of waste tire rubber powder to recycled fiber is (5 to 10):(1 to 3); the particle size of the waste tire rubber powder is less than 0.5 mm; The recycled fiber is sourced from waste fishing nets, industrial non-woven fabrics, and fibers in waste yachts; the particle size of the recycled fiber is 2 to 5 mm.

9. The preparation method of the subgrade filling material according to any one of claims 1 to 8, characterized in that, It includes the following steps: (1) Mix the gold flotation tailings and the modified precipitation material evenly to obtain the first mixture; (2) After ball-milling the curing agent and the activator, obtain the second mixture; (3) Mix the first mixture, the second mixture, the solid modifier, and the crack-resistant agent evenly, form, and cure to obtain the subgrade filler based on high-water-content gold flotation tailings.

10. The preparation method according to claim 9, characterized in that, In step (1), the mixing is carried out by stirring, the stirring rate is 25 to 35 r / min, and the stirring time is 10 to 20 min; In step (2), the rotation speed of ball milling is 400 - 500 r / min, the time of ball milling is 2 - 3 min, and the specific surface area of the second mixture after ball milling is greater than 450 m 2 / kg.

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