Solid waste-based mine filling material and preparation method thereof

Abstract

The invention belongs to the technical field of mine filling materials, and discloses a solid-waste-based mine filling material and a preparation method thereof. The filling material comprises 70-100 parts of red mud, 1-10 parts of fly ash, 1-10 parts of slag, 5-20 parts of an acid activator, 10-30 parts of aggregate, 1-5 parts of a water reducing agent and 50-100 parts of water. The doping amount of the red mud of the filling material can reach 60% or above, the red mud is used as a main cementing material, formic acid, acetic acid, oxalic acid and other small-molecular organic acids are used as an acid activator, and an acid environment provided by the acid activator can reduce the alkalinity of the red mud and promote the dissolution of the red mud; the water and calcium silicate in the red mud can be more easily subjected to hydration reaction to generate a large amount of hydration products such as C-S-H gel, so that the strength of the filling material is enhanced. The acid activator used in the invention is low in cost, the cementing material and the aggregate are industrial solid wastes, and the cost of the mine filling material is reduced while the problem of resource utilization of the industrial solid wastes is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of mine filling materials, and in particular to a solid waste-based mine filling material and a preparation method thereof. Background Art

[0002] Red mud is an industrial solid waste discharged when the aluminum industry extracts alumina. Due to the differences in ore grade, production method and technical level, about 1.0 to 1.8 tons of red mud are discharged for every ton of alumina produced. Red mud is an insoluble residue, which can be divided into sintering red mud, Bayer red mud and combined red mud. The main components are SiO2, Al2O3, CaO, Fe2O3, etc. With the development of the aluminum industry and the reduction of bauxite ore grade, the output of red mud is getting higher and higher. Red mud is an alkaline substance. Due to the flushing of rainwater, the alkali in the red mud will be dissolved, which may pollute surface water and groundwater. Therefore, the large-scale storage of red mud has caused more and more serious pollution to the environment, and the comprehensive utilization of red mud has become an important research topic.

[0003] At present, the comprehensive utilization of red mud mainly includes the field of building materials, wastewater and waste gas treatment materials, agricultural fertilizers, etc., but the comprehensive utilization rate of red mud is less than 15%, and a large amount of red mud is still not effectively utilized. Some scholars have proposed to use red mud to replace cement for concrete or cementitious materials, but studies have found that when red mud replaces cement by more than 15%, the compressive strength and flexural strength of the material decrease significantly. Patent CN115974433A discloses a red mud-based cementitious material, including gypsum, mineral powder, red mud, fly ash and activator, in which the mass content of red mud reaches 10-25%, the 28d compressive strength of the cementitious material reaches 40-55MPa, and the 28d flexural strength reaches 7-9MPa. Patent CN118108476A discloses a red mud synergistic multi-source solid filling material, including red mud, desulfurized ash, cement, sodium dodecyl sulfate, mirabilite, gypsum, cementitious material, mineral powder, activator, stimulant, accelerator, water and water reducer, wherein the red mud content is about 50%, and the 28d compressive strength reaches 42-46MPa. The red mud content in the above prior art is still relatively low, and the preparation of red mud-based cementitious materials with a high content of more than 60% cannot be achieved. Summary of the invention

[0004] The object of the present invention is to provide a solid waste-based mine filling material and a preparation method thereof, so as to solve the problem of low red mud content in existing cementitious materials.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0007] 70-100 parts of red mud, 1-10 parts of fly ash, 1-10 parts of slag, 5-20 parts of acid activator, 10-30 parts of aggregate, 1-5 parts of water reducer, 50-100 parts of water;

[0008] Wherein, the acid activator includes one or more of formic acid, acetic acid and oxalic acid.

[0009] Preferably, in the above-mentioned solid waste-based mine filling material, the red mud is one or more of Bayer process red mud, sintering process red mud, and combined process red mud; the water content of the red mud is ≤5%.

[0010] Preferably, in the above-mentioned solid waste-based mine filling material, the particle size of the fly ash is 0.01-0.1 mm; the particle size of the slag is 0.1-1 mm.

[0011] Preferably, in the above-mentioned solid waste-based mine filling material, the aggregate includes recycled micropowder from construction waste and recycled fine aggregate from construction waste; the mass ratio of the recycled micropowder from construction waste to the recycled fine aggregate from construction waste is 1-3:1-2.

[0012] Preferably, in the above-mentioned solid waste-based mine filling material, the particle size of the recycled construction waste micropowder is 0.01-1 mm; the particle size of the recycled construction waste fine aggregate is 1-5 mm.

[0013] Preferably, in the above-mentioned solid waste-based mine filling material, the mass fraction of the acid activator is 10 parts.

[0014] Preferably, in the above-mentioned solid waste-based mine filling material, the acid activator is formic acid and acetic acid in a mass ratio of 4:1.

[0015] The present invention also provides a method for preparing a solid waste-based mine filling material, comprising the following steps:

[0016] Red mud, fly ash, slag, acid activator, aggregate, water reducing agent and water are mixed to obtain slurry; the slurry is cured to obtain solid waste-based mine filling material.

[0017] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention uses red mud, fly ash, and slag as the main gelling materials, small molecule organic acid as the acid activator, and construction waste recycled powder as the aggregate, wherein the red mud content can reach more than 60%, and a high-content red mud-based filling material is prepared. The filling material has an initial setting time of about 6 hours and a final setting time of about 15 hours, good fluidity, and a 28d compressive strength of 7.8Mpa, which meets the requirements of mine filling.

[0019] (2) The main gelling material in the filling material of the present invention is alkaline red mud, and small molecule organic acids such as formic acid, acetic acid, and oxalic acid are used as acid activators. The acidic environment provided by the acid activator can reduce the alkalinity of the red mud, promote the dissolution of the red mud, and make it easier for water to react with calcium silicate in the red mud to generate a large amount of hydration products such as CSH gel, thereby enhancing the strength of the filling material. In addition, the raw materials of the small molecule organic acid activator used in the present invention are easy to obtain and low in cost. By controlling the amount of the activator, the hydration reaction can be effectively promoted to obtain a mine filling material that meets the filling strength requirements.

[0020] (3) The raw materials used in the present invention are all industrial solid waste, and no high-cost cementitious materials such as cement are added. While solving the problem of resource utilization of industrial solid waste, it also greatly reduces the cost of mine filling materials. DETAILED DESCRIPTION

[0021] The present invention provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0022] 70-100 parts of red mud, 1-10 parts of fly ash, 1-10 parts of slag, 5-20 parts of acid activator, 10-30 parts of aggregate, 1-5 parts of water reducer, and 50-100 parts of water.

[0023] In the present invention, the mass fraction of the red mud is preferably 72 to 95 parts, more preferably 77 to 84 parts, and even more preferably 80 parts.

[0024] In the present invention, the mass fraction of the fly ash is preferably 3 to 9 parts, more preferably 5 to 8 parts, and even more preferably 7 parts.

[0025] In the present invention, the mass fraction of the slag is preferably 2 to 8 parts, more preferably 4 to 7 parts, and even more preferably 5 parts.

[0026] In the present invention, the weight percentage of the acid activator is preferably 7 to 17 parts, more preferably 9 to 12 parts, and even more preferably 10 parts.

[0027] In the present invention, the mass fraction of the aggregate is preferably 13 to 26 parts, more preferably 15 to 21 parts, and even more preferably 20 parts.

[0028] In the present invention, the mass fraction of the water reducing agent is preferably 1.5 to 4 parts, more preferably 2 to 3 parts, and more preferably 2 parts.

[0029] In the present invention, the mass fraction of the water is preferably 60 to 90 parts, more preferably 70 to 80 parts, and even more preferably 75 parts.

[0030] In the present invention, the red mud is preferably one or more of Bayer red mud, sintering red mud, and combined red mud; the water content of the red mud is preferably ≤5%, more preferably ≤3%, and more preferably ≤2%; the particle size of the red mud is preferably 0.01-1 mm, more preferably 0.1-1 mm, and more preferably 0.5-1 mm. The chemical composition of the red mud used in the embodiment of the present invention includes, by mass fraction: Al2O3 28.33%, SiO2 27.88%, CaO 18.69%, Fe2O3 9.82%, Na2O 5.12%, TiO2 4.43%, K2O 2.39%, SO3 1.3%, MgO 1.2%, P2O5 0.27%, and other impurities 0.57%.

[0031] In the present invention, the acid activator preferably includes one or more of formic acid, acetic acid, and oxalic acid, more preferably a mixture of formic acid and acetic acid, and more preferably a mixture of formic acid and acetic acid in a mass ratio of 4:1.

[0032] In the present invention, the particle size of the fly ash is preferably 0.01-0.1 mm, more preferably 0.01-0.07 mm, and more preferably 0.01-0.05 mm. The chemical composition of the fly ash used in the embodiment of the present invention includes, by mass fraction, SiO251.52%, Al2O327.93%, Fe2O39.63%, TiO22.72%, CaO 2.11%, SO31.75%, Na2O1.52%, K2O 1.45%, MgO 0.837%, P2O50.153%, V2O50.0848%, ZnO 0.0556%, and other impurities 0.2396%.

[0033] In the present invention, the particle size of the slag is preferably 0.1-1 mm, more preferably 0.1-0.6 mm, and more preferably 0.1-0.5 mm. The chemical composition of the slag used in the embodiment of the present invention includes, by mass fraction, CaO 35.56%, SiO2 32.26%, Al2O3 17.58%, MgO 9.25%, Fe2O3 0.83%, SnO 0.37%, and other impurities 4.15%.

[0034] In the present invention, the aggregate preferably includes recycled micropowder from construction waste and recycled fine aggregate from construction waste; the mass ratio of the recycled micropowder from construction waste to recycled fine aggregate from construction waste is preferably 1-3:1-2, more preferably 2-3:1-1.5, and more preferably 3:1.

[0035] In the present invention, the construction waste recycled micro-powder and construction waste recycled fine aggregate are obtained by crushing and sorting construction waste; the particle size of the construction waste recycled micro-powder is preferably 0.01-1 mm, more preferably 0.1-1 mm, and more preferably 0.5-1 mm; the particle size of the construction waste recycled fine aggregate is preferably 1-5 mm, more preferably 2-4 mm, and more preferably 2-3 mm.

[0036] In the present invention, the water reducer is preferably a polycarboxylate water reducer.

[0037] The present invention also provides a method for preparing a solid waste-based mine filling material, comprising the following steps:

[0038] Red mud, fly ash, slag, acid activator, aggregate, water reducing agent and water are mixed to obtain slurry; the slurry is cured to obtain solid waste-based mine filling material.

[0039] In the present invention, the curing is preferably first performed in a curing box at a humidity of 80% and a temperature of 25° C. for 12 hours, and then cured under standard conditions to a specified age.

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0043] 70 parts of red mud, 10 parts of fly ash, 5 parts of slag, 12 parts of formic acid, 10 parts of construction waste recycled micropowder, 20 parts of construction waste recycled fine aggregate, 2 parts of polycarboxylate water reducer, and 70 parts of water.

[0044] Among them, the moisture content of red mud is ≤5%; the particle size of red mud is 0.01-0.1mm; the particle size of fly ash is 0.05-0.1mm; the particle size of slag is 0.1-0.5mm; the particle size of recycled micro powder of construction waste is 0.1-0.5mm; the particle size of recycled fine aggregate of construction waste is 1-2mm.

[0045] The preparation method of the solid waste-based mine filling material comprises the following steps:

[0046] Red mud, fly ash, slag, formic acid, recycled micro powder of construction waste and recycled fine aggregate of construction waste are stirred and mixed evenly, water is added and stirred evenly, and then polycarboxylic acid water reducer is added and stirred evenly to obtain slurry; after the slurry is loaded into a mold, it is cured in a curing box with a humidity of 80% and a temperature of 25°C for 12 hours, and then cured under standard conditions to the specified age.

[0047] Example 2

[0048] This embodiment provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0049] 75 parts of red mud, 2 parts of fly ash, 1 part of slag, 7 parts of oxalic acid, 1 part of acetic acid, 5 parts of recycled micropowder from construction waste, 5 parts of recycled fine aggregate from construction waste, 3 parts of polycarboxylate water reducer, and 80 parts of water.

[0050] Among them, the moisture content of red mud is ≤5%; the particle size of red mud is 0.1-1mm; the particle size of fly ash is 0.05-0.1mm; the particle size of slag is 0.1-1mm; the particle size of recycled micro powder of construction waste is 0.5-1mm; the particle size of recycled fine aggregate of construction waste is 2-3mm.

[0051] The preparation method of the solid waste-based mine filling material comprises the following steps:

[0052] Red mud, fly ash, slag, oxalic acid, acetic acid, recycled micro powder of construction waste and recycled fine aggregate of construction waste are stirred evenly, water is added and stirred evenly, and then polycarboxylic acid water reducer is added and stirred evenly to obtain slurry; after the slurry is loaded into a mold, it is cured in a curing box at a humidity of 80% and a temperature of 25°C for 12 hours, and then cured under standard conditions to the specified age.

[0053] Example 3

[0054] This embodiment provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0055] 80 parts of red mud, 7 parts of fly ash, 5 parts of slag, 8 parts of formic acid, 2 parts of acetic acid, 15 parts of recycled micropowder from construction waste, 5 parts of recycled fine aggregate from construction waste, 2 parts of polycarboxylate water reducer, and 75 parts of water.

[0056] Among them, the moisture content of red mud is ≤2%; the particle size of red mud is 0.5-1mm; the particle size of fly ash is 0.01-0.05mm; the particle size of slag is 0.1-1mm; the particle size of recycled micro powder of construction waste is 0.5-1mm; the particle size of recycled fine aggregate of construction waste is 2-3mm.

[0057] The preparation method of the solid waste-based mine filling material comprises the following steps:

[0058] Red mud, fly ash, slag, formic acid, acetic acid, recycled micro powder of construction waste and recycled fine aggregate of construction waste are stirred and mixed evenly, water is added and stirred evenly, and then polycarboxylic acid water reducer is added and stirred evenly to obtain slurry; after the slurry is loaded into a mold, it is cured in a curing box at a humidity of 80% and a temperature of 25°C for 12 hours, and then cured under standard conditions to the specified age.

[0059] Example 4

[0060] This embodiment provides a solid waste-based mine filling material, comprising the following raw materials in parts by weight:

[0061] 90 parts of red mud, 5 parts of fly ash, 5 parts of slag, 5 parts of oxalic acid, 10 parts of acetic acid, 15 parts of recycled micropowder from construction waste, 10 parts of recycled fine aggregate from construction waste, 4 parts of polycarboxylate water reducer, and 80 parts of water.

[0062] Among them, the moisture content of red mud is ≤5%; the particle size of red mud is 0.1-1mm; the particle size of fly ash is 0.05-0.1mm; the particle size of slag is 0.1-1mm; the particle size of recycled micro powder of construction waste is 0.7-1mm; the particle size of recycled fine aggregate of construction waste is 3-5mm.

[0063] The preparation method of the solid waste-based mine filling material comprises the following steps:

[0064] Red mud, fly ash, slag, oxalic acid, acetic acid, recycled micro powder of construction waste and recycled fine aggregate of construction waste are stirred evenly, water is added and stirred evenly, and then polycarboxylic acid water reducer is added and stirred evenly to obtain slurry; after the slurry is loaded into a mold, it is cured in a curing box at a humidity of 80% and a temperature of 25°C for 12 hours, and then cured under standard conditions to the specified age.

[0065] Comparative Example 1

[0066] This comparative example provides a solid waste-based mine filling material, which is specifically referred to in Example 1, except that fly ash and slag are removed.

[0067] Comparative Example 2

[0068] This comparative example provides a solid waste-based mine filling material, which is specifically referred to in Example 1, except that the fly ash is removed.

[0069] Comparative Example 3

[0070] This comparative example provides a solid waste-based mine filling material, which is specifically referred to in Example 1, except that the slag is removed.

[0071] The solid waste-based mine filling materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to setting time test, fluidity test, slump test and mechanical property test. The results are shown in Table 1.

[0072] Table 1 Results of setting time, fluidity, slump and mechanical properties of solid waste-based mine filling materials

[0073]

[0074] As can be seen from Table 1, the change in the composition of the cementitious material has little effect on the setting time, fluidity and slump of the filling material. The cementitious material of the present invention is mainly composed of red mud, and the red mud content can reach more than 60%. The obtained filling material has an initial setting time of about 6 hours and a final setting time of about 13.6 to 15 hours. It has good fluidity and a 28d compressive strength of more than 7Mpa, which meets the mine filling requirements.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A solid waste-based mine filling material, characterized in that: Contains the following raw materials in parts by weight: 70-100 parts of red mud, 1-10 parts of fly ash, 1-10 parts of slag, 5-20 parts of acid activator, 10-30 parts of aggregate, 1-5 parts of water reducer, 50-100 parts of water; Wherein, the acid activator includes one or more of formic acid, acetic acid and oxalic acid.

2. A solid waste-based mine filling material according to claim 1, characterized in that: The red mud is one or more of Bayer process red mud, sintering process red mud and combined process red mud; the water content of the red mud is ≤5%.

3. The solid waste-based mine filling material according to claim 1, characterized in that: The particle size of the fly ash is 0.01-0.1 mm; the particle size of the slag is 0.1-1 mm.

4. A solid waste-based mine filling material according to any one of claims 1 to 3, characterized in that: The aggregate comprises recycled micro powder from construction waste and recycled fine aggregate from construction waste; the mass ratio of the recycled micro powder from construction waste to the recycled fine aggregate from construction waste is 1-3:1-2.

5. The solid waste-based mine filling material according to claim 4, characterized in that: The particle size of the construction waste recycled micro powder is 0.01-1 mm; the particle size of the construction waste recycled fine aggregate is 1-5 mm.

6. The solid waste-based mine filling material according to claim 5, characterized in that: The mass fraction of the acid activator is 10 parts.

7. A solid waste-based mine filling material according to claim 1 or 6, characterized in that: The acid activator is formic acid and acetic acid in a mass ratio of 4:

1.

8. The method for preparing a solid waste-based mine filling material according to any one of claims 1 to 7, characterized in that: The following steps are involved: Red mud, fly ash, slag, acid activator, aggregate, water reducing agent and water are mixed to obtain slurry; the slurry is cured to obtain solid waste-based mine filling material.

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