A roadbed filler based on high-water-cut gold flotation tailings and its preparation method

Abstract

The application relates to the technical field of roadbed engineering, in particular to a roadbed filler based on high-water-content gold flotation tailings and a preparation method thereof.A roadbed filler based on high-water-content gold flotation tailings is prepared from the following raw materials: gold flotation tailings, modified precipitation material, curing agent, activator, solid modifier and anti-cracking agent; the water content of the gold flotation tailings is lower than 20%; in the application, the porous precipitation material and the low-carbon cementing material are used to perform pre-dehydration treatment and efficient curing treatment on the high-water-content gold flotation tailings, so that the roadbed filler with low carbon and low cost and with high strength and low shrinkage is obtained.

Description

Technical Field

[0001] This invention relates to the field of roadbed engineering technology, specifically to a roadbed filler based on high-water-content gold flotation tailings and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With the rapid development of highway construction, the demand for natural filling materials such as soil and stone in roadbed construction is huge. The traditional soil extraction and road construction mode causes serious damage to natural resources and the environment. Therefore, there is an urgent need for alternative roadbed filling materials.

[0004] Gold tailings are solid wastes discharged after gold or other useful components are recovered from gold ore through beneficiation or gold extraction processes. They are generally divided into gold flotation tailings and cyanide tailings. Gold flotation tailings are the tailings produced simultaneously when gold concentrate is extracted from crushed and ground ore using flotation processes. They are classified as general solid waste and account for over 97% of the total gold tailings generated. Gold flotation tailings contain over 80% inorganic minerals such as silicon and aluminum oxides, and their composition is similar to that of raw materials for many building materials. Therefore, theoretically, gold flotation tailings can be used to prepare engineering materials. However, their high moisture content makes them prone to liquefaction and insufficient strength when directly used for filling. Furthermore, single physical dewatering processes (such as drying and filtration) are energy-intensive and time-consuming, making large-scale, rapid, and direct application in engineering materials impossible.

[0005] Currently, attempts are being made to use gold flotation tailings for roadbed filling, but traditional curing agents (such as cement) have significant drawbacks: on the one hand, cement production has high carbon emissions (approximately 0.8 tons of CO2 are emitted per ton of cement); on the other hand, cement curing of gold tailings is easily affected by high moisture content, resulting in insufficient cementation reaction, leading to low strength and poor durability of the cured body. It is necessary to add 10% to 20% cement or composite curing agent to meet the requirements of the roadbed, which limits the economy and sustainability. Summary of the Invention

[0006] To overcome the above problems, the present invention provides a roadbed filler based on high water content gold flotation tailings and its preparation method.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a roadbed filler based on high-water-content gold flotation tailings, wherein the raw materials comprise, by weight:

[0009] 100-150 parts of gold flotation tailings, 20-30 parts of modified precipitation material, 5-10 parts of solidifying agent, 0.5-2 parts of activator, 0.1-0.5 parts of solid modifier, and 0.1-0.2 parts of crack-resistant agent;

[0010] Among them, the moisture content of the gold flotation tailings is less than 20%;

[0011] The modified precipitation material is obtained by modifying 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;

[0012] The curing agent includes slag, coal gasification slag powder, steel slag powder, incinerated waste, and gypsum;

[0013] The activator includes carbide slag, sodium sulfate, and red mud;

[0014] The solid modifiers include carboxymethyl cellulose, calcium formate, sodium nitrite, and calcium sulfoaluminate;

[0015] The crack-resistant agent includes waste tire rubber powder and recycled fibers.

[0016] In one or more embodiments, the particle size of the gold flotation tailings is less than 15 mm. This particle size limitation is due to two reasons: firstly, the filler particle size is required to be no greater than 15 mm 40 cm below the subgrade surface of highways / first-class roads; secondly, coarse particles are inconvenient for construction.

[0017] In one or more embodiments, the precipitation material has a particle size of less than 5 mm and a water absorption rate of greater than 5%. The small particle size (<5 mm) is limited to allow the precipitation material to enter the interior of the gold flotation tailings and be evenly distributed; the high water absorption rate (>5%) is to allow it to adsorb free water in the gold flotation tailings.

[0018] In one or more embodiments, the concentration (mass fraction) of phosphoric acid in the first modifier is 6-10%, preferably 8%.

[0019] In one or more embodiments, the oxygen content of the graphene oxide in the first modifier is 24-30%, preferably 25%; the thickness is 0.8-2 nm, preferably 1 nm. Limiting the oxygen content of the graphene oxide achieves a balance between chemical activity and structural integrity, ensuring that the graphene oxide can serve as a reaction platform while retaining its functionalization potential; limiting the thickness is to maintain the limiting mechanical and transport properties of the nanosheets and avoid performance degradation caused by stacking.

[0020] In one or more embodiments, the mass ratio of sodium silicate to graphene oxide in the first modifier is (1~1.5):1. Sodium silicate forms a -Si-O-Si- three-dimensional network in water, which encapsulates the graphene oxide sheets, thereby enhancing mechanical strength. If the ratio is too low (<1:1), it will cause problems such as sparse gel network, brittle composite material, and insufficient mechanical properties. If the ratio is too high (>1.5:1), it will cause problems such as excessive gel covering the GO surface, shielding its functionality (such as conductivity and adsorption sites), excessive material rigidity, and decreased toughness.

[0021] In one or more embodiments, the preparation method of the modified precipitation material includes the following steps:

[0022] Precipitation material was immersed in a phosphoric acid solution for acid washing, then removed, washed with water until neutral, and dried to obtain pretreated precipitation material.

[0023] Sodium silicate was dispersed in water to obtain an aqueous sodium silicate solution; then graphene oxide was added and fully dispersed to obtain a modified sodium silicate aqueous solution.

[0024] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution, removed, and dried to obtain the modified precipitation material.

[0025] Preferably, the pickling process takes 20-30 minutes and the temperature is 40-60 °C.

[0026] Preferably, the pretreated precipitation material is immersed in a modified sodium silicate aqueous solution and ultrasonically treated for 15-30 minutes.

[0027] Preferably, the concentration (mass fraction) of sodium silicate in the sodium silicate aqueous solution is 8-12%, more preferably 10%.

[0028] Preferably, the mass ratio of the pretreated precipitation material to the modified sodium silicate aqueous solution is (10~12):1.

[0029] Under the aforementioned conditions, the pretreated precipitation material can fully contact the modified sodium silicate aqueous solution, thereby completing the modification.

[0030] In one or more embodiments, the mass ratio of slag, coal gasification slag powder, steel slag powder, incinerated waste and gypsum in the curing agent is (25~50):(15~30):(10~30):(15~25):(5~15).

[0031] In one or more embodiments, the slag in the curing agent is of grade S95 or higher, and the SiO2 and CaO content is greater than 75%.

[0032] In one or more embodiments, the content of SiO2+CaO+Al2O3 in the coal gasification slag powder in the curing agent is greater than 80%.

[0033] In one or more embodiments, the content of SiO2+Al2O3 in the incinerated waste is greater than 50% in the curing agent.

[0034] In one or more embodiments, the gypsum in the curing agent is selected from one or more of titanium gypsum, phosphogypsum, or fluorogypsum.

[0035] In one or more embodiments, the mass ratio of carbide slag, sodium sulfate and red mud in the activator is (5~10):(1~2):(5~10).

[0036] In one or more embodiments, the activator contains more than 65% Ca(OH)2 in the carbide slag.

[0037] In one or more embodiments, the red mud in the activator has a pH greater than 12.

[0038] In one or more embodiments, the mass ratio of carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate in the solid modifier is (1~2):(0.5~1):(2~3):(3~5).

[0039] In one or more embodiments, calcium sulfoaluminate in the solid modifier is a white powder with a specific surface area ≥400 m². 2 / kg.

[0040] In one or more embodiments, the mass ratio of waste tire rubber powder to recycled fiber in the crack-resistant agent is (5~10):(1~3).

[0041] In one or more embodiments, the particle size of waste tire rubber powder is less than 0.5 mm. Limiting the particle size of waste tire rubber powder in highway subgrade filling materials to less than 0.5 mm is because: this size is the critical threshold for rubber powder to transform from a "discrete dopant" into a "functionalized soil component," exceeding this limit will lead to a systematic deterioration of engineering performance; by constraining the size, the microscale fusion of the concrete matrix and the rubber additive phase is achieved, transforming waste tires from an environmental burden into a high-value subgrade improvement material.

[0042] In one or more embodiments, the recycled fibers are derived from discarded fishing nets, industrial nonwoven fabrics, and scrapped yachts; the particle size of the recycled fibers is 2-5 mm. This limitation is the critical size for transforming discarded fibers from "physical impurities" into "intelligent crack-resistant skeletons," achieving a millimeter-level precision to reconcile the contradictions between strength requirements, ecological risks, and engineering efficiency.

[0043] A second aspect of the present invention provides a method for preparing roadbed filler based on high-water-content gold flotation tailings as described in the first aspect, comprising the following steps:

[0044] (1) Mix the gold flotation tailings and modified precipitation material evenly to obtain the first mixture;

[0045] (2) The curing agent and activator are ball-milled to obtain a second mixture;

[0046] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain the roadbed filler based on high water content gold flotation tailings.

[0047] In one or more embodiments, in step (1), mixing is carried out by stirring at a rate of 25-35 r / min for a duration of 10-20 min.

[0048] In one or more embodiments, in step (2), the ball mill rotation speed 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 m². 2 / kg.

[0049] The beneficial effects of this invention are as follows:

[0050] (1) In this invention, porous precipitation materials and low-carbon cementitious materials are used to pre-dehydrate and efficiently solidify gold flotation tailings with high water content, thereby obtaining roadbed filler with low carbon content, low cost, high strength, and low shrinkage. The precipitation materials are modified by a first modifier to obtain porous modified precipitation materials. Specifically, the carbonate impurities, metal oxides, and some silicate pollutants in the pores of the precipitation materials are dissolved by phosphoric acid solution to clear the pores; the precipitation materials are impregnated with sodium silicate solution and graphene oxide to form a hydrophilic coating, and the high specific surface area and hydrophilic properties of graphene oxide are used to enhance water absorption and form a micro-water storage network; the porous precipitation materials quickly adsorb free water in the gold flotation tailings, reducing the water content of the gold flotation tailings to the optimal water content, and the porous precipitation materials absorb The attached free water provides sufficient moisture for the later hydration reaction of the low-carbon cementitious material, acting as a reservoir to effectively prevent cracking and shrinkage of the roadbed filler. The low-carbon cementitious material uses slag, coal gasification slag powder, steel slag powder, incinerated waste, gypsum, and an activator. Slag, coal gasification slag powder, and incinerated waste provide CaO, SiO2, and Al2O3, which form CSH and CASH gels during hydration, becoming the main source of strength. The high alkalinity (pH>12) of steel slag powder promotes the dissolution of active Si / Al from coal gasification slag powder, while gypsum provides SO42-. 2- With Al 3+The reaction produces ettringite, forming an interwoven network structure that improves mechanical strength. The activator increases the alkalinity of the system, promoting the breaking of Si-O and Al-O bonds in slag and steel slag, thus accelerating the hydration reaction. The hydroxyl (-OH) and carboxyl (-COOH) groups in the carboxymethyl cellulose molecular chain can form hydrogen bonds with hydration products (such as CSH gel), improving the compactness 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, promoting the early formation of CSH gel and ettringite (AFt), and reducing porosity through interfacial reinforcement. Waste tire rubber powder and recycled fibers work synergistically through multiple pathways of "elastic buffering - reinforcement - porosity control," effectively solving the problem of insufficient strength of roadbed fillers in high-water-content gold tailings.

[0051] (2) The roadbed filler provided by the present invention meets the strength requirements of the current "Highway Roadbed Design Specification" (JTG D30), can effectively prevent roadbed cracking, and also improves the freeze-thaw resistance and extends the service life of the roadbed.

[0052] (3) This invention utilizes multi-source solid waste to completely replace cement in the preparation of cementitious materials 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, which is conducive to promoting the full utilization of bulk solid waste. Detailed Implementation

[0053] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0054] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0055] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0056] The chemical composition of slag, coal gasification slag powder, steel slag powder, incinerated waste, gypsum, carbide slag, red mud and gold flotation tailings in the following examples is shown in Table 1.

[0057] Table 1 Oxide Content of Raw Materials

[0058]

[0059] In the following examples, the gold flotation tailings have a moisture content of 18% and a particle size of less than 13 mm.

[0060] The precipitation material has a particle size of less than 5 mm and a water absorption rate of more than 5%.

[0061] The slag in the curing agent is grade S95 or higher; the steel slag powder is calcined at high temperature or chemically activated, with a specific surface area ≥400m². 2 / kg, activity index: ≥65% after 7 days, ≥85% after 28 days.

[0062] The sodium sulfate in the activator has a purity of ≥92%; the pH of the red mud is 12.7;

[0063] The solid modifier contains carboxymethyl cellulose with an industrial-grade purity ≥98% and a water retention rate ≥95%; calcium formate with an industrial-grade purity ≥95%; sodium nitrite with an industrial-grade purity ≥96%; and calcium sulfoaluminate with a specific surface area ≥400 m². 2 / kg.

[0064] The recycled fibers were selected from discarded fishing nets, and the fiber particle size was 3 mm.

[0065] The particle size of waste tire rubber powder is less than 0.5 mm.

[0066] Example 1

[0067] The raw material formula for a roadbed filler based on high water content gold flotation tailings is shown in Table 2.

[0068] Table 2 Raw material formula (parts by mass)

[0069]

[0070] In this embodiment, the modified precipitation material is modified coal slag; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste and gypsum, with a mass ratio of 25:15:10:15:5; the activator is carbide slag, sodium sulfate and red mud, with a mass ratio of 10:2:10; the solid modifier is carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate, with a mass ratio of 1:0.5:2:3; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 10:3.

[0071] The preparation methods for modified precipitation materials include:

[0072] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:4, the acid washing temperature was 40 ℃ and the time was 25 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0073] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of 1:1; and the solution was ultrasonically treated for 25 min to obtain a modified sodium silicate aqueous solution.

[0074] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 10:1, ultrasonically treated for 20 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0075] Preparation of roadbed filler based on high water content gold flotation tailings:

[0076] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 10 min at a speed of 25 r / min to obtain the first mixture, which is then stored for later use.

[0077] (2) The curing agent and activator were ball-milled for 2 minutes at a speed of 400 r / min to obtain a uniform second mixture with a specific surface area of ​​450 m². 2 / kg, keep for future use;

[0078] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0079] Example 2

[0080] The raw material formula for a roadbed filler based on high water content gold flotation tailings is shown in Table 3.

[0081] Table 3 Raw material formula (parts by mass)

[0082]

[0083] In this embodiment, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste and gypsum, with a mass ratio of 35:30:20:25:15; the activator is carbide slag, sodium sulfate and red mud, with a mass ratio of 5:2:5; the solid modifier is carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate, with a mass ratio of 2:0.8:3:5; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 5:1.

[0084] The preparation methods for modified precipitation materials include:

[0085] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:3, the acid washing temperature was 60 ℃ and the time was 30 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0086] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of sodium silicate to graphene oxide of 1.2:1; and the solution was ultrasonically treated for 30 min to obtain a modified sodium silicate aqueous solution.

[0087] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 11:1, ultrasonically treated for 25 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0088] Preparation of roadbed filler based on high water content gold flotation tailings:

[0089] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 20 min at a speed of 35 r / min to obtain the first mixture, which is then stored for later use.

[0090] (2) The curing agent and activator were ball-milled for 3 minutes at a speed of 500 r / min to obtain a uniform second mixture with a specific surface area of ​​550 m². 2 / kg, keep for future use;

[0091] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0092] Example 3

[0093] The raw material formula for a roadbed filler based on high water content gold flotation tailings is shown in Table 4.

[0094] Table 4 Raw material formula (parts by mass)

[0095]

[0096] In this embodiment, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste 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; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0097] The preparation methods for modified precipitation materials include:

[0098] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:5, the acid washing temperature was 40 ℃ and the time was 20 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0099] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of 1:1; and the solution was ultrasonically treated for 25 min to obtain a modified sodium silicate aqueous solution.

[0100] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 10:1, ultrasonically treated for 30 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0101] Preparation of roadbed filler based on high water content gold flotation tailings:

[0102] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 15 min at a speed of 30 r / min to obtain the first mixture, which is then stored for later use.

[0103] (2) The curing agent and activator were ball-milled for 2 minutes at a speed of 450 r / min to obtain a uniform second mixture with a specific surface area of ​​480 m². 2 / kg, keep for future use;

[0104] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0105] Example 4

[0106] The raw material formulation for a roadbed filler based on high-water-content gold flotation tailings is shown in Table 5.

[0107] Table 5 Raw material formula (parts by mass)

[0108]

[0109] In this embodiment, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste 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; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0110] The preparation methods for modified precipitation materials include:

[0111] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:3, the acid washing temperature was 60 ℃ and the time was 25 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0112] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of sodium silicate to graphene oxide of 1.5:1; and the solution was ultrasonically treated for 30 min to obtain a modified sodium silicate aqueous solution.

[0113] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 10:1, ultrasonically treated for 15 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0114] Preparation of roadbed filler based on high water content gold flotation tailings:

[0115] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 10 min at a speed of 35 r / min to obtain the first mixture, which is then stored for later use.

[0116] (2) The curing agent and activator were ball-milled for 3 minutes at a speed of 400 r / min to obtain a uniform second mixture with a specific surface area of ​​520 m². 2 / kg, keep for future use;

[0117] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0118] Example 5

[0119] The raw material formula for a roadbed filler based on high water content gold flotation tailings is shown in Table 6.

[0120] Table 6 Raw material formula (parts by mass)

[0121]

[0122] In this embodiment, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste 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; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0123] The preparation methods for modified precipitation materials include:

[0124] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:5, the acid washing temperature was 50 ℃ and the time was 30 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0125] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of sodium silicate to graphene oxide of 1.2:1; and the solution was ultrasonically treated for 25 min to obtain a modified sodium silicate aqueous solution.

[0126] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 12:1, ultrasonically treated for 30 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0127] Preparation of roadbed filler based on high water content gold flotation tailings:

[0128] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 20 min at a speed of 25 r / min to obtain the first mixture, which is then stored for later use.

[0129] (2) The curing agent and activator were ball-milled for 3 minutes at a speed of 400 r / min to obtain a uniform second mixture with a specific surface area of ​​470 m². 2 / kg, keep for future use;

[0130] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0131] Example 6

[0132] The raw material formulation for a roadbed filler based on high-water-content gold flotation tailings is shown in Table 7.

[0133] Table 7 Raw material formula (parts by mass)

[0134]

[0135] In this embodiment, the modified precipitation material is modified coal gangue; the curing agent is slag, coal gasification slag powder, steel slag powder, incinerated waste 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; and the crack-resistant agent is waste tire rubber powder and recycled fiber, with a mass ratio of 7:2.

[0136] The preparation methods for modified precipitation materials include:

[0137] Precipitation material was immersed in a phosphoric acid solution with a concentration (mass fraction) of 8%, the mass ratio of precipitation material to phosphoric acid solution was 1:4, the acid washing temperature was 50 ℃ and the time was 30 min. After acid washing, the precipitation material was repeatedly washed with deionized water until neutral, and then dried in an oven at 105 ℃ for 6 h to obtain pretreated precipitation material.

[0138] Sodium silicate was ultrasonically dispersed in water to obtain a sodium silicate aqueous solution with a concentration (mass fraction) of 10%; graphene oxide was added to the sodium silicate aqueous solution at a mass ratio of sodium silicate to graphene oxide of 1.5:1; and the solution was ultrasonically treated for 30 min to obtain a modified sodium silicate aqueous solution.

[0139] The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution at a mass ratio of 10:1, ultrasonically treated for 20 min, and dried (in an oven at 105 ℃ for 6 h) to obtain the modified precipitation material.

[0140] Preparation of roadbed filler based on high water content gold flotation tailings:

[0141] (1) Mix the gold flotation tailings and modified precipitation material in a dry large concrete mixer for 18 min at a speed of 25 r / min to obtain the first mixture, which is then stored for later use.

[0142] (2) The curing agent and activator were ball-milled for 3 minutes at a speed of 480 r / min to obtain a uniform second mixture with a specific surface area of ​​490 m². 2 / kg, keep for future use;

[0143] (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain roadbed filler based on high water content gold flotation tailings.

[0144] Comparative Example 1

[0145] The difference between this comparative example and Example 1 is that the raw materials do not contain modified precipitation materials. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0146] Comparative Example 2

[0147] 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 in Example 1 and will not be repeated here.

[0148] Comparative Example 3

[0149] The difference between this comparative example and Example 1 is that the curing agent and activator in the raw materials are replaced by cement. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0150] Comparative Example 4

[0151] The difference between this comparative example and Example 1 is that the raw materials do not contain crack-resistant agents. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0152] Comparative Example 5

[0153] The difference between this comparative example and Example 1 is that the raw materials do not contain solid modifiers. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0154] Performance verification:

[0155] Based on the Technical Specifications for Highway Subgrade Construction (JTG D30) and the actual field conditions, CBR tests and drying shrinkage tests were conducted on the subgrade filler specimens of high water content flotation gold tailings in Examples 1-6 and Comparative Examples 1-5. The test results are shown in Table 8.

[0156] Table 8 Test Results

[0157]

[0158] As shown in Table 8, the CBR values ​​of the examples are all higher than those of the comparative examples, and exceed the 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%. Simultaneously, the drying shrinkage strain freeze-thaw mass loss in the examples is less than that in the comparative examples, indicating that the subgrade filler prepared in the examples performs better than the subgrade filler obtained in the comparative examples. Through Examples 1 and Comparative Examples 1-5, it can be seen that the technical solution of the present invention significantly improves the performance of the subgrade filler through a triple mechanism of porous precipitation material modification, synergistic effect of solid waste-based cementitious system, and enhancement by functional additives. Comparative Example 1 (without precipitation material) was unable to adsorb free water, resulting in an overly wet mixture that could not be molded. Comparative Example 2 (unmodified precipitation material) had poor dewatering efficiency for gold tailings due to pore blockage and poor surface hydrophilicity, and its CBR value did not meet the requirements. Comparative Example 3 (cement replacing low-carbon cementitious material) lacked the synergistic effect of multi-source industrial solid waste activity and could not form a large network cementitious system in a water-rich environment. Comparative Example 4 (without crack-resistant agent) lacked the elastic sulfur bond network of rubber particles and the synergistic effect of chemical bridging on the fiber surface, resulting in large drying shrinkage strain. Comparative Example 5 (without solid modifier) ​​reduced the early formation of CSH gel and ettringite (AFt), reduced the density of the microstructure, and further reduced the curing effect of the curing agent. The advantages of Examples 1-6 are as follows: Acid washing combined with sodium silicate and graphene oxide coating optimizes the water storage-release balance in the pores of the precipitation material. Utilizing a multi-source industrial solid waste synergistic activation mechanism, it promotes the decomposition and release of active silicate and aluminate ions from the silica-alumina components in the solid waste. Combined with modifiers and crack-resistant agents, the released active ions form chemical bridges with the elastic sulfur bond network of rubber particles and the fiber surface, ultimately constructing a "rigid-flexible" composite system at the microscopic level—containing both a rigid framework of C-(A)-SH gel and an embedded elastic rubber microphase and fiber-reinforced interface. This multi-level synergistic effect enables the material to achieve breakthroughs in both low shrinkage and freeze-thaw resistance. The absence of any single component in the comparative examples disrupts this synergistic logic, confirming the systematic nature and irreplaceability of the technical solution of this invention.

[0159] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A roadbed filler based on high-water-cut gold flotation tailings, characterized in that, Its raw materials consist of the following components in parts by weight: 100-150 parts of gold flotation tailings, 20-30 parts of modified precipitation material, 5-10 parts of curing agent, 0.5-2 parts of activator, 0.1-0.5 parts of solid modifier, and 0.1-0.2 parts of crack-resistant agent; Among them, the moisture content of gold flotation tailings is less than 20%; The modified precipitation material is obtained by modifying 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; in the first modifier, the mass ratio of sodium silicate to graphene oxide is (1~1.5):1; the precipitation material has a particle size of less than 5 mm and a water absorption rate of more than 5%; the preparation method of the modified precipitation material includes the following steps: Precipitation material was immersed in a phosphoric acid solution for acid washing, then removed, washed with water until neutral, and dried to obtain pretreated precipitation material. Sodium silicate was dispersed in water to obtain an aqueous solution of sodium silicate; then graphene oxide was added and dispersed thoroughly to obtain a modified aqueous solution of sodium silicate. The pretreated precipitation material was immersed in a modified sodium silicate aqueous solution, removed, and dried to obtain the modified precipitation material. The curing agent is composed of slag, coal gasification slag powder, steel slag powder, incinerated waste and gypsum; the mass ratio of slag, coal gasification slag powder, steel slag powder, incinerated waste and gypsum is (25~50):(15~30):(10~30):(15~25):(5~15); The activator is composed of carbide slag, sodium sulfate and red mud; the mass ratio of carbide slag, sodium sulfate and red mud in the activator is (5~10):(1~2):(5~10). The solid modifier is composed of carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate; the mass ratio of carboxymethyl cellulose, calcium formate, sodium nitrite and calcium sulfoaluminate in the solid modifier is (1~2):(0.5~1):(2~3):(3~5). The crack-resistant agent comprises waste tire rubber powder and recycled fiber, with a mass ratio of waste tire rubber powder to recycled fiber of (5~10):(1~3); the particle size of the waste tire rubber powder is less than 0.5 mm.

2. The roadbed filler material as described in claim 1, characterized in that, The particle size of gold flotation tailings is less than 15 mm.

3. The roadbed filler material as described in 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.

4. The roadbed filler material as described in claim 3, characterized in that, During the pickling process, the treatment time is 20-30 minutes 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 an aqueous solution is 8-12%. The mass ratio of the pretreated precipitation material to the modified sodium silicate aqueous solution is (10~12):

1.

5. The roadbed filler material as described in claim 1, characterized in that, The slag in the curing agent is grade S95 or higher, and the SiO2 and CaO content is greater than 75%. The curing agent contains more than 80% SiO2+CaO+Al2O3 in the coal gasification slag powder; The solidifying agent contains more than 50% SiO2+Al2O3 in the incinerated waste; In the curing agent, the gypsum is selected from one or more of titanium gypsum, phosphogypsum, and fluorogypsum.

6. The roadbed filler material as described in claim 1, characterized in that, In the activator, the Ca(OH)2 content in the carbide slag is greater than 65%; The activator contains red mud with a pH greater than 12.

7. The roadbed filler material as described in claim 1, characterized in that, In the crack-resistant agent, the mass ratio of waste tire rubber powder to recycled fiber is (5~10):(1~3); the particle size of the waste tire rubber powder is less than 0.5 mm; The recycled fibers are derived from discarded fishing nets, industrial non-woven fabrics, and fibers from scrap yachts; the particle size of the recycled fibers is 2-5 mm.

8. The method for preparing roadbed filler material according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Mix the gold flotation tailings and modified precipitation material evenly to obtain the first mixture; (2) After ball milling the curing agent and activator, a second mixture is obtained; (3) Mix the first mixture, the second mixture, the solid modifier and the crack-resistant agent evenly, shape and cure to obtain the roadbed filler based on high water content gold flotation tailings.

9. The preparation method according to claim 8, characterized in that, In step (1), mixing is carried out by stirring at a speed of 25-35 r / min for a duration of 10-20 min. In step (2), the ball mill speed 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 m². 2 / kg.

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