Red-mud-based backfilling paste and preparation method therefor

Abstract

The present disclosure relates to a method for preparing a red-mud-based backfilling paste. The method comprises: grinding and mixing industrial solid waste, an adsorbent and red mud, so as to obtain a ground powder; subjecting the ground powder to dry-process activation under the condition of a preset temperature, so as to obtain a gelled powder; mixing Bayer-process red mud, aggregates and the gelled powder, so as to obtain a dry pre-backfilling material having a mixed red mud component; and mixing an acidic activator, a water reducer, water and the dry pre-backfilling material having the mixed red mud component, so as to obtain a red-mud-based backfilling paste, wherein the preset temperature is less than or equal to 350°C.

Description

A filling paste based on red mud and a preparation method Cross-reference to Related Applications

[0001] This application claims priority to Chinese Patent Application No. 202411282192.X, filed September 13, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of solid waste comprehensive recycling, and in particular to a filling paste based on red mud and a preparation method. BACKGROUND

[0003] At present, a large number of underground goaf areas are formed due to mining activities in domestic mines. If these underground goaf areas are not treated by filling, they will cause great hidden dangers to the safety of engineering activities and surface buildings above the goaf areas. At present, the underground goaf areas of mines are generally cemented and filled with mining by using cementitious materials as base materials. However, the use of cement will increase the filling cost of underground goaf areas, which will undoubtedly restrict the sustainable development of mining enterprises using cemented filling mining method. Red mud is the largest solid waste generated by the aluminum industry, and it has potential cementitious activity. However, the comprehensive utilization rate of red mud is less than 10%. If red mud can be modified and prepared into a cement substitute, it will undoubtedly reduce the filling cost of mining enterprises using cemented filling mining method, improve economic benefits, and help to realize large-scale consumption of red mud and promote the green and sustainable development of the aluminum industry.

[0004] Due to the low strength of red mud, the current technology for preparing filling materials based on red mud needs to reduce the amount of red mud in the filling materials for consideration of compressive strength, and most of the filling materials also need to use red mud together with cement and solid alkali agent and other high-cost materials to meet the use requirements of the filling materials, which undoubtedly increases the cost of red mud as a filling material.

[0005] For example, the current technology for preparing filling materials based on red mud includes: (1) a Bayer process red mud-based filling material, a preparation method thereof, and an application thereof, which uses red mud, fly ash, and cement to form a basic filling material, and uses inorganic salts, organic acids, and neutral mineral admixtures to form a solid alkali material, to prepare the filling material from the two. (2) A method for preparing a coal mine residual mining area filling paste using red mud, which first crushes and sieves coal gangue to prepare coarse and fine aggregates, and uses water reducing agent, early strength agent, expansive agent, and retarder to the fine aggregate to obtain the filling material. (3) A filling material mixed with red mud, desulfurized gypsum, and slag, and a preparation method thereof, which uses fixed red mud, slag, and desulfurized gypsum to prepare a cementitious material, and then mixes coal gangue as aggregate to obtain the filling material. SUMMARY

[0006] The problem of how to improve the compressive strength of filling materials prepared based on red mud is solved by using one or more embodiments of the present disclosure.

[0007] In a first aspect, a preparation method of a red mud-based filling paste according to some embodiments of the present disclosure includes: grinding and mixing industrial solid waste, adsorbent, and red mud to obtain ground powder; dry-activating the ground powder at a preset temperature to activate the cementitious components of the red mud and the adsorption performance of the adsorbent in the ground powder, to obtain a cementitious powder; mixing Bayer process red mud, aggregate, and the cementitious powder to obtain a pre-filling dry material with mixed red mud components; and mixing an acid activator, a water reducing agent, water, and the pre-filling dry material with mixed red mud components to obtain a red mud-based filling paste; wherein the preset temperature is ≤350°C.

[0008] In a second aspect, a red mud-based filling paste according to some embodiments of the present disclosure is obtained by the preparation method of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0009] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the related art, the drawings needed to be used in the embodiments or related art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0011] FIG. 1 shows a flowchart of a preparation method of a red mud-based filling paste according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present disclosure with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, any other embodiments obtained by a person of ordinary skill in the art without creative effort are within the protection scope of the present disclosure.

[0013] Various embodiments of the present disclosure can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limit to the scope of the present disclosure; therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values in the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers in the range, such as 1, 2, 3, 4, 5, and 6, which applies to any range; in addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) in the indicated range.

[0014] In this document, the term includes “comprises” and the like means “including but not limited to”. “And / or”, describing the association relationship of the associated objects, means that there can be three kinds of relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone; where A and B can be singular or plural. “At least one” means one or more, “multiple” means two or more; “at least one”, “at least one of the following” or the like means any combination of these items, including any combination of single item or multiple items; for example, “at least one of a, b, or c”, or “at least one of a, b, and c”, can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in the present disclosure can be purchased from the market or can be prepared by existing methods.

[0015] It should be noted that for the related technology (1) described in the background art, the inventors found that the amount of red mud is small (the weight of red mud is only 30% to 60% of the total weight of the basic filling material), and in addition, a large amount of cement and solid alkali material is additionally required; for the related technology (2) described in the background art, the inventors found that the amount of red mud is small, and the cost of preparing the filling material is high; for the related technology (3) described in the background art, the inventors found that the amount of red mud is small.

[0016] Therefore, the common problem in these related technologies is that the amount of red mud is small, and it also needs to be used with cement, solid alkali agent and other high-cost materials, which undoubtedly increases the cost of the filling material.

[0017] FIG. 1 shows a flowchart of a preparation method of a red mud-based filling paste according to some embodiments of the present disclosure. As shown in FIG. 1, the preparation method of the red mud-based filling paste according to some embodiments of the present disclosure includes:

[0018] S1. mixing red mud, industrial solid waste and adsorbent, and grinding to obtain a ground powder;

[0019] S2. dry-activating the ground powder at a preset temperature to obtain a cementitious powder material with a red mud component;

[0020] S3. mixing the cementitious powder material with a red mud component, Bayer red mud and aggregate to obtain a pre-filling dry material with a mixed red mud component; and

[0021] S4. mixing the pre-filling dry material with a mixed red mud component, an acid activator, a water reducing agent and water to obtain a red mud-based filling paste;

[0022] wherein the preset temperature is ≤ 350°C.

[0023] It should be noted that the red mud described above can be Bayer red mud, sintered red mud, or a mixture of Bayer red mud and sintered red mud. It should be noted that in the above embodiments, the heat required for dry activation can be the flue gas waste heat of an alumina calcination furnace, the residual heat of a calcination furnace, or the flue gas waste heat of a rotary kiln, and the heat generated during the production process of aluminum electrolysis can be recycled.

[0024] In some optional embodiments, dry-activating the ground powder at a preset temperature is used to activate the cementitious components of the red mud in the ground powder and the adsorption performance of the adsorbent; and mixing the pre-filling dry material with a mixed red mud component, an acid activator, a water reducing agent and water is used to activate the cementitious effect of the mixed red mud component in the pre-filling dry material by the acid activator.

[0025] In the embodiments, the gel component in the red mud in the ground powder can be activated by dry activation of the ground powder under preset temperature conditions, and the adsorption performance of the adsorbent in the ground powder can also be activated, thereby facilitating the adsorption of the red mud and the industrial solid waste together by the activated adsorbent and the cementation combination of the red mud and the industrial solid waste by the activated gel component.

[0026] In the embodiments, the acid activator can activate the cementation of the mixed red mud component in the pre-filled dry material, and the mixed red mud and the industrial solid waste can be cemented and combined by the cementation of the mixed red mud component. In some alternative embodiments, the preset temperature is 120-350°C, and the dry activation time is 10-60 min.

[0027] In the embodiments, the preset temperature can be 120-350°C, and the dry activation time can be 10-60 min, so that the gel component in the red mud in the ground powder can be activated and the adsorption performance of the adsorbent can also be activated based on the dry activation at a low temperature of 120-350°C. The activated adsorbent adsorbs the red mud and the industrial solid waste together by adsorption, and the red mud and the industrial solid waste are cemented and combined by the cementation of the activated red mud, so that the cemented powder material can be obtained. The activated adsorbent can also inhibit the migration of heavy metal ions in the industrial solid waste and the red mud, avoid the damage to the cementation of the activated red mud by the migration of these heavy metal ions, and obtain the cemented powder material with good cementation performance.

[0028] In some embodiments, the preset temperature can be 120°C, 130°C, 140°C, 150°C, 200°C, 250°C, 300°C, or 350°C.

[0029] In some embodiments, the dry activation time can be 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min.

[0030] In some alternative embodiments, the components of the ground powder satisfy: red mud: 10-50 parts, industrial solid waste: 40-80 parts, and adsorbent: 1-10 parts by weight.

[0031] In these embodiments, the components of the ground powder material can satisfy that the red mud is 10-50 parts, the industrial solid waste is 40-80 parts, and the adsorbent is 1-10 parts, so as to make the ground powder material have sufficient red mud, industrial solid waste and adsorbent. After the dry activation treatment, the sufficient red mud, industrial solid waste and adsorbent can activate the cementitious components of the red mud in the ground powder material and activate the adsorption performance of the adsorbent. After the activation, the adsorbent can adsorb the red mud and the industrial solid waste together through the adsorption effect, and then the red mud and the industrial solid waste are cemented and combined through the cementation of the activated red mud, to obtain the cemented powder material. In addition, the activated adsorbent can also inhibit the migration of heavy metal ions in the industrial solid waste and the red mud, so as to avoid the migration of these heavy metal ions from damaging the cementation of the activated red mud, so as to obtain the cemented powder material with good cementation performance.

[0032] In some embodiments, the red mud can be 10 parts, 20 parts, 30 parts, 40 parts or 50 parts by weight.

[0033] In some embodiments, the industrial solid waste can be 40 parts, 50 parts, 60 parts, 70 parts or 80 parts by weight.

[0034] In some embodiments, the adsorbent can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts by weight.

[0035] In some optional embodiments, the industrial solid waste includes at least two of:

[0036] fly ash, slag powder, slag, carbide slag and desulfurization gypsum; and / or,

[0037] The adsorbent includes at least one of:

[0038] montmorillonite, sepiolite and diatomite.

[0039] In these embodiments, the industrial solid waste can include at least two of fly ash, slag powder, slag, carbide slag, and desulfurization gypsum, and the adsorbent can include at least one of montmorillonite, sepiolite, and diatomite, so that the preparation raw material of the red mud-based filling paste can cover most of the industrial solid waste and the adsorbent, on the one hand, the adsorption performance of the adsorbent in the ground powder can be activated by dry activation, the activated adsorbent can adsorb the red mud and the industrial solid waste together by adsorption, and the activated adsorbent can also inhibit the migration of heavy metal ions in the industrial solid waste and the red mud, so as to avoid the damage of the migration of these heavy metal ions to the cementation of the activated red mud, so as to obtain a cementation powder material with good cementation performance; on the other hand, most of the industrial solid waste and the adsorbent can be recycled and utilized, and the economic value and environmental protection value are improved.

[0040] In some optional embodiments, the particle size of the ground powder is < 178 μm.

[0041] In these embodiments, the particle size of the ground powder can be less than 178 μm, which can make the ground powder have a sufficiently small particle size, and the ground powder with a sufficiently small particle size can facilitate the dry activation on the one hand, and can also facilitate the mixing of the ground powder, the bayer red mud and the aggregate on the other hand, and the high strength characteristics of the aggregate can be used subsequently to improve the strength of the filling paste, so that the pre-filled dry material can be obtained.

[0042] In some embodiments, the particle size of the ground powder can be 177 μm, 170 μm, 160 μm, 150 μm, 140 μm, 130 μm, 120 μm, 110 μm, 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm or 10 μm.

[0043] In some optional embodiments, the components of the pre-filled dry material include, by weight fraction:

[0044] The cementation powder material: 10-30 parts, the bayer red mud: 20-60 parts, and the aggregate: 0-80 parts.

[0045] In these embodiments, the components of the pre-filled dry material can include 10-30 parts of the cementation powder material, 20-60 parts of the bayer red mud, and 0-80 parts of the aggregate, which can make the pre-filled dry material have sufficient cementation powder material, bayer red mud and aggregate, so that the bayer red mud and the aggregate can be further cemented together by the cementation powder material, the high strength characteristics of the aggregate can be used to improve the compressive strength of the filling paste, and the subsequent forming of the filling paste can be facilitated.

[0046] In some embodiments, the weight fraction of the cementitious powder material can be 10 parts, 15 parts, 20 parts, 25 parts, or 30 parts.

[0047] In some embodiments, the weight fraction of the Bayer process red mud can be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, or 60 parts.

[0048] In some embodiments, the weight fraction of the aggregate can be 0 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, or 80 parts.

[0049] In some alternative embodiments, the aggregate comprises at least one of:

[0050] Rubble, tailings, and slag.

[0051] In these embodiments, the aggregate can comprise at least one of rubble, tailings, and slag, and the high strength characteristics of the aggregate can improve the compressive strength of the filling paste, thereby increasing the doping amount of the red mud.

[0052] It should be noted that the particle size of the aggregate can be 0.15 mm to 5 mm, which has a positive effect of improving the volume stability, workability, and strength of the filling paste.

[0053] In some alternative embodiments, the weight m1 of the acidic activator and the weight m2 of the pre-filling dry material satisfy the relationship:

[0054] m1:m2 = (0.2-2.0):100;

[0055] The weight m3 of the water-reducing agent and the weight m2 of the pre-filling dry material satisfy the relationship:

[0056] m3:m2 = (0.2-1.0):100; and the weight m4 of the water and the total weight m5 of the pre-filling dry material, the acidic activator, and the water-reducing agent satisfy the relationship:

[0057] m4:m5 = (0.5-1.0):1.

[0058] In these embodiments, the weight m1 of the acidic activator and the weight m2 of the pre-filling dry material can satisfy the relationship m1:m2 = (0.2-2.0):100, which can facilitate a sufficient amount of the acidic activator in the pre-filling dry material, and the sufficient amount of the acidic activator can activate the cementation of the cementitious powder material in the pre-filling dry material to further cement completely between the Bayer process red mud and the aggregate in the pre-filling dry material, and the high strength characteristics of the aggregate can improve the compressive strength of the filling paste.

[0059] In these embodiments, the weight m3 of the water-reducing agent and the weight m2 of the pre-packed dry material can satisfy the relationship m3:m2=(0.2-1.0):100, so that the pre-packed dry material has sufficient water-reducing agent, and the sufficient water-reducing agent is in water or forms a colloidal material, and the colloidal material can improve the cementation strength of the cementing powder material, so as to improve the compressive strength of the packing paste.

[0060] In these embodiments, the weight m4 of the water and the total weight m5 of the pre-packed dry material, the acid activator and the water-reducing agent can satisfy the relationship m4:m5=(0.5-1.0):1, and the pre-packed dry material and the acid activator can be effectively dispersed by the dispersion of water, and the pre-packed dry material, the acid activator and the water-reducing agent can be uniformly mixed, and the three uniformly mixed can activate the cementation of the cementing powder material in the pre-packed dry material, so as to completely cement the Bayer red mud and the aggregate in the pre-packed dry material, and improve the compressive strength of the packing paste by the high strength characteristics of the aggregate. At the same time, the collocation of water and water-reducing agent can improve the cementation strength of the cementing powder material by the water-reducing agent under the condition of reducing the water content of the packing paste, so as to improve the compressive strength of the packing paste.

[0061] In some embodiments, the weight m1 of the acid activator and the weight m2 of the pre-packed dry material can satisfy the relationship m1:m2=0.2:100, m1:m2=0.3:100, m1:m2=0.4:100, m1:m2=0.5:100, m1:m2=0.6:100, m1:m2=0.7:100, m1:m2=0.8:100, m1:m2=0.9:100, m1:m2=1.0:100, m1:m2=1.1:100, m1:m2=1.2:100, m1:m2=1.3:100, m1:m2=1.4:100, m1:m2=1.5:100, m1:m2=1.6:100, m1:m2=1.7:100, m1:m2=1.8:100, m1:m2=1.9:100 or m1:m2=2.0:100.

[0062] In some embodiments, the weight m3 of the water-reducing agent and the weight m2 of the pre-packed dry material can satisfy the relationship m3:m2=0.2:100, m3:m2=0.3:100, m3:m2=0.4:100, m3:m2=0.5:100, m3:m2=0.6:100, m3:m2=0.7:100, m3:m2=0.8:100, m3:m2=0.9:100 or m3:m2=1.0:100.

[0063] In some embodiments, the weight m4 of the water and the total weight m5 of the pre-filled dry material, the acidic activator and the water-reducing agent can satisfy the relationship m4:m5=0.5:1, m4:m5=0.6:1, m4:m5=0.7:1, m4:m5=0.8:1, m4:m5=0.9:1 or m4:m5=1.0:1.

[0064] In some alternative embodiments, the acidic activator comprises at least one of:

[0065] acetic acid, phosphoric acid and aluminum dihydrogen phosphate; and / or,

[0066] The water-reducing agent comprises at least one of:

[0067] lignin sulfonate, naphthalene-based superplasticizer, polycarboxylate-based superplasticizer and sulfamate superplasticizer.

[0068] In these embodiments, the acidic activator can comprise at least one of acetic acid, phosphoric acid and aluminum dihydrogen phosphate, can activate the gelation of the gelatinous powder in the pre-filled dry material through the activation of the acidic activator, and the gelatinous powder with the gelation can gel completely between the Bayer process red mud and the aggregate in the pre-filled dry material, so as to facilitate the improvement of the strength of the filling paste through the high-strength characteristics of the aggregate.

[0069] In these embodiments, the water-reducing agent can comprise at least one of lignin sulfonate, naphthalene-based superplasticizer, polycarboxylate-based superplasticizer and sulfamate superplasticizer, can improve the gelation strength of the gelatinous powder through the water-reducing agent in the case of reducing the water content of the filling paste, so as to improve the compressive strength of the filling paste.

[0070] Based on a general inventive concept, a red mud-based filling paste according to some embodiments of the present disclosure is obtained by the above preparation method. The red mud-based filling paste is realized based on the above preparation method, and the specific steps of the preparation method can refer to the above embodiments. Since the red mud-based filling paste adopts part or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0071] It should be noted that since the red mud-based filling paste has high compressive strength, it can accommodate more red mud raw materials to improve the doping amount of red mud under the condition that the red mud-based filling paste meets the performance requirements of the filling material.

[0072] The technical solutions of the present disclosure are further described below in combination with specific examples. The experimental methods not specified in the following examples are generally determined according to industry standards; if there is no corresponding industry standard, the methods are determined according to the general international standards, conventional conditions, or the conditions recommended by the manufacturers.

[0073] Example 1

[0074] As shown in FIG. 1, the present embodiment discloses a preparation method of a filling paste based on red mud, comprising:

[0075] S1. Grinding and mixing industrial solid waste, adsorbent and Bayer process red mud to obtain ground powder;

[0076] S2. Dry-activating the ground powder at a preset temperature to activate the cementitious components of the red mud and the adsorption performance of the adsorbent in the ground powder, to obtain a cementitious powder material with red mud components;

[0077] S3. Mixing the cementitious powder material with red mud components, Bayer process red mud and aggregate to obtain a pre-filling dry material with mixed red mud components; and,

[0078] S4. Mixing an acid activator, a water reducing agent, water and the pre-filling dry material with mixed red mud components to activate the cementitious effect of the mixed red mud components in the pre-filling dry material by the acid activator, to obtain a filling paste based on red mud;

[0079] The preset temperature is 350°C, and the dry-activation time is 60 min.

[0080] The components of the ground powder satisfy, in terms of weight fraction:

[0081] Bayer process red mud: 10 parts, industrial solid waste: 80 parts and adsorbent: 10 parts.

[0082] The industrial solid waste includes, in terms of weight fraction:

[0083] Fly ash: 30 parts, slag powder: 30 parts and desulfurization gypsum: 20 parts.

[0084] The adsorbent is montmorillonite.

[0085] The particle size of the ground powder is < 178 μm.

[0086] The components of the pre-filling dry material include, in terms of weight fraction:

[0087] Cementitious powder material: 30 parts, Bayer process red mud: 20 parts and aggregate: 50 parts.

[0088] The aggregate is tailings.

[0089] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material satisfy the relationship:

[0090] m1:m2 = 2.0:100.

[0091] The weight m3 of the water-reducing agent and the weight m2 of the pre-filled dry material satisfy the relationship:

[0092] m3:m2 = 1.0:100.

[0093] The weight m4 of the water and the total weight m5 of the pre-filled dry material, the acidic activator and the water-reducing agent satisfy the relationship:

[0094] m4:m5 = 0.5:1.

[0095] The acidic activator is acetic acid.

[0096] The water-reducing agent is a naphthalene-based superplasticizer.

[0097] Example 2

[0098] Based on the disclosure of Example 1, the following modifications are further made:

[0099] The preset temperature is 120°C, and the time for dry activation is 10 min.

[0100] The components of the ground powder material satisfy, in terms of weight fraction:

[0101] Red mud: 50 parts, industrial solid waste: 40 parts and adsorbent: 10 parts.

[0102] The industrial solid waste includes, in terms of weight fraction:

[0103] Fly ash: 20 parts, carbide slag: 10 parts and desulfurization gypsum: 10 parts.

[0104] The adsorbent is sepiolite.

[0105] The components of the pre-filled dry material include, in terms of weight fraction:

[0106] Cementitious powder material: 10 parts, Bayer red mud: 60 parts and aggregate: 30 parts.

[0107] The aggregate is tailings.

[0108] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material satisfy the relationship:

[0109] m1:m2 = 0.2:100.

[0110] The weight m3 of the water-reducing agent and the weight m2 of the pre-filled dry material satisfy the relationship:

[0111] m3:m2 = 0.2:100.

[0112] The weight m4 of water and the total weight m5 of the pre-filled dry materials, the acid activator and the water-reducing agent satisfy the relationship:

[0113] m4:m5 = 0.8:1.

[0114] The acid activator is phosphoric acid.

[0115] The water-reducing agent is a naphthalene-based high-efficiency water-reducing agent.

[0116] Example 3

[0117] On the basis of the disclosure of Example 1, the following modifications are further made:

[0118] The preset temperature is 150℃, and the time for dry activation is 20 min.

[0119] The components of the ground powder meet the following relationship in terms of weight fraction:

[0120] Red mud: 20 parts, industrial solid waste: 79 parts and adsorbent: 1 part.

[0121] The industrial solid waste includes the following in terms of weight fraction:

[0122] Fly ash: 39 parts, slag: 20 parts and desulfurization gypsum: 20 parts.

[0123] The adsorbent is sepiolite.

[0124] The components of the pre-filled dry materials include the following in terms of weight fraction:

[0125] Cementitious powder: 25 parts, Bayer red mud: 50 parts and aggregate: 25 parts.

[0126] The aggregate is crushed stone.

[0127] The weight m1 of the acid activator and the weight m2 of the pre-filled dry materials satisfy the relationship:

[0128] m1:m2 = 1.5:100.

[0129] The weight m3 of the water-reducing agent and the weight m2 of the pre-filled dry materials satisfy the relationship: m3:m2 = 1.0:100.

[0130] The weight m4 of water and the total weight m5 of the pre-filled dry materials, the acid activator and the water-reducing agent satisfy the relationship:

[0131] m4:m5 = 0.65:1.

[0132] The acid activator is acetic acid.

[0133] The water-reducing agent is a naphthalene-based high-efficiency water-reducing agent.

[0134] Example 4

[0135] On the basis of the disclosure of Example 1, the following modifications are further made:

[0136] The preset temperature is 200℃, and the time for dry activation is 30min.

[0137] The components of the ground powder meet the following requirements in terms of weight fraction:

[0138] Red mud: 25 parts, industrial solid waste: 60 parts, and adsorbent: 8 parts.

[0139] The industrial solid waste includes the following components in terms of weight fraction:

[0140] Fly ash: 25 parts, slag powder: 25 parts, and desulfurization gypsum: 10 parts;

[0141] The adsorbent is diatomite.

[0142] The components of the pre-filled dry material include the following in terms of weight fraction:

[0143] Cementitious powder material: 25 parts, Bayer red mud: 40 parts, and aggregate: 35 parts.

[0144] The aggregate is slag.

[0145] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material meet the following relationship:

[0146] m1:m2 = 1.2:100.

[0147] The weight m3 of the water reducing agent and the weight m2 of the pre-filled dry material meet the following relationship:

[0148] m3:m2 = 0.5:100.

[0149] The weight m4 of the water and the total weight m5 of the pre-filled dry material, the acidic activator, and the water reducing agent meet the following relationship:

[0150] m4:m5 = 0.75:1.

[0151] The acidic activator is aluminum dihydrogen phosphate.

[0152] The water reducing agent is sulfamate water reducing agent.

[0153] Example 5

[0154] On the basis of the disclosure of Example 1, the following modifications are further made:

[0155] The preset temperature is 250℃, and the time for dry activation is 40min.

[0156] The components of the ground powder meet the following requirements in terms of weight parts:

[0157] Red mud: 15 parts, industrial solid waste: 80 parts, and adsorbent: 5 parts.

[0158] The industrial solid waste includes the following components in terms of weight parts:

[0159] Fly ash: 25 parts, slag powder: 30 parts, and desulfurization gypsum: 25 parts;

[0160] The adsorbent is diatomite.

[0161] The components of the pre-filled dry material meet the following requirements in terms of weight parts:

[0162] Cementitious powder material: 25 parts, Bayer red mud: 50 parts, and aggregate: 25 parts.

[0163] The aggregate is gravel.

[0164] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material meet the following relationship:

[0165] m1:m2 = 0.3:100.

[0166] The weight m3 of the water-reducing agent and the weight m2 of the pre-filled dry material meet the following relationship:

[0167] m3:m2 = 0.5:100.

[0168] The weight m4 of the water and the total weight m5 of the pre-filled dry material, the acidic activator, and the water-reducing agent meet the following relationship:

[0169] m4:m5 = 0.75:1.

[0170] The acidic activator is acetic acid.

[0171] The water-reducing agent is a polycarboxylate-based water-reducing agent.

[0172] Example 6

[0173] Based on the disclosure of Example 1, the following modifications are further made:

[0174] The preset temperature is 250°C, and the time for dry activation is 40 min.

[0175] The components of the ground powder meet the following requirements in terms of weight parts:

[0176] Red mud: 19 parts, industrial solid waste: 80 parts, and adsorbent: 1 part.

[0177] The industrial solid waste includes the following components in terms of weight parts:

[0178] Fly ash: 25 parts, slag powder: 30 parts and desulfurization gypsum: 25 parts;

[0179] The adsorbent is sepiolite.

[0180] The components of the pre-filled dry material include, in parts by weight:

[0181] Cementitious powder material: 25 parts, Bayer red mud: 50 parts and aggregate: 25 parts.

[0182] The aggregate is crushed stone.

[0183] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material satisfy the relationship:

[0184] m1:m2 = 0.3:100.

[0185] The weight m3 of the water reducing agent and the weight m2 of the pre-filled dry material satisfy the relationship:

[0186] m3:m2 = 0.5:100.

[0187] The weight m4 of the water and the total weight m5 of the pre-filled dry material, the acidic activator and the water reducing agent satisfy the relationship:

[0188] m4:m5 = 0.75:1.

[0189] The acidic activator is acetic acid.

[0190] The water reducing agent is a polycarboxylate-based water reducing agent.

[0191] Example 7

[0192] Based on the disclosure of Example 1, the following modifications are further made:

[0193] The preset temperature is 300℃ and the time of dry activation is 45 min.

[0194] The components of the ground powder material satisfy, in parts by weight:

[0195] Sintered red mud: 19 parts, industrial solid waste: 80 parts and adsorbent: 1 part.

[0196] The industrial solid waste includes, in parts by weight:

[0197] Fly ash: 25 parts, slag powder: 30 parts and desulfurization gypsum: 25 parts;

[0198] The adsorbent is montmorillonite.

[0199] The components of the pre-filled dry material include, in parts by weight:

[0200] Gelled powder material: 10 parts, Bayer process red mud: 60 parts and aggregate: 30 parts.

[0201] The aggregate is slag.

[0202] The weight m1 of the acidic activator and the weight m2 of the pre-packed dry material satisfy the relationship:

[0203] m1:m2 = 0.2:100.

[0204] The weight m3 of the water-reducing agent and the weight m2 of the pre-packed dry material satisfy the relationship:

[0205] m3:m2 = 0.5:100.

[0206] The weight m4 of the water and the total weight m5 of the pre-packed dry material, the acidic activator and the water-reducing agent satisfy the relationship: m4:m5 = 0.85:1.

[0207] The acidic activator is aluminum dihydrogen phosphate.

[0208] The water-reducing agent is lignin sulfonate.

[0209] Example 8

[0210] Based on the disclosure of Example 1, the following modifications are further made:

[0211] The preset temperature is 300°C and the time of dry activation is 45 min.

[0212] The components of the ground powder material satisfy, in parts by weight:

[0213] Bayer process red mud: 19 parts, industrial solid waste: 80 parts and adsorbent: 1 part.

[0214] The industrial solid waste includes, in parts by weight:

[0215] Fly ash: 25 parts, slag powder: 30 parts and desulfurization gypsum: 25 parts;

[0216] The adsorbent is montmorillonite.

[0217] The components of the pre-packed dry material include, in parts by weight:

[0218] Gelled powder material: 10 parts, Bayer process red mud: 60 parts and aggregate: 30 parts.

[0219] The aggregate is slag.

[0220] The weight m1 of the acidic activator and the weight m2 of the pre-packed dry material satisfy the relationship:

[0221] m1:m2 = 1.8:100.

[0222] The weight m3 of the water reducing agent and the weight m2 of the pre-packed dry material satisfy the relationship:

[0223] m3:m2 = 0.5:100.

[0224] The weight m4 of the water and the total weight m5 of the pre-packed dry material, the acidic activator and the water reducing agent satisfy the relationship: m4:m5 = 0.85:1.

[0225] The acidic activator is acetic acid.

[0226] The water reducing agent is lignin sulfonate.

[0227] Comparative Example 1

[0228] On the basis of the disclosure of Example 1, the following modifications are further made:

[0229] Dry activation is not used.

[0230] Comparative Example 2

[0231] On the basis of the disclosure of Example 1, the following modifications are further made:

[0232] The preset temperature is 100℃ and the time of dry activation is 5min.

[0233] Comparative Example 3

[0234] On the basis of the disclosure of Example 1, the following modifications are further made:

[0235] The preset temperature is 400℃ and the time of dry activation is 80min.

[0236] Comparative Example 4

[0237] On the basis of the disclosure of Example 1, the following modifications are further made:

[0238] No adsorbent is added. The components of the ground powder meet the following relationship in terms of weight fraction:

[0239] Bayer process red mud: 20 parts and industrial solid waste: 80 parts.

[0240] Comparative Example 5

[0241] On the basis of the disclosure of Example 1, the following modifications are further made:

[0242] The components of the ground powder meet the following relationship in terms of weight fraction:

[0243] The weight fraction of the adsorbent is 20 parts.

[0244] Comparative Example 6

[0245] On the basis of the disclosure of Example 1, the following modifications are further made:

[0246] The components of the pre-filled dry material include, in parts by weight:

[0247] The weight fraction of the gelled powder material is 5 parts.

[0248] Comparative Example 7

[0249] On the basis of the disclosure of Example 1, the following modifications are further made:

[0250] The components of the pre-filled dry material include, in parts by weight:

[0251] The weight fraction of the gelled powder material is 40 parts.

[0252] Comparative Example 8

[0253] On the basis of the disclosure of Example 1, the following modifications are further made:

[0254]

[0255] No acidic activator is used.

[0256] Comparative Example 9

[0257] On the basis of the disclosure of Example 1, the following modifications are further made:

[0258] The weight m1 of the acidic activator and the weight m2 of the pre-filled dry material satisfy the relationship:

[0259] m1:m2 = 5.0:100.

[0260] Related experiments and effect data:

[0261] The compressive strength of the red mud-based filling paste obtained in each example and comparative example is tested for 3 days (3d) and 7 days (7d), respectively, and the pH of the leaching liquid of the red mud-based filling paste is detected, and the results are shown in Table 1; at the same time, the harmful factors of the leaching liquid of the red mud-based filling paste can be detected according to the groundwater quality standard (GB14848-2017) Class III water index, and the results are shown in Table 2.

[0262] Table 1 Compressive strength test and leaching liquid pH detection results of red mud-based filling paste of each example and comparative example

[0263] Table 2 Harmful factor detection results of leaching liquid of red mud-based filling paste of each example and comparative example

[0264] As can be seen from Table 1 and Table 2, the red mud-based filling paste prepared by the preparation method of the red mud-based filling paste disclosed in the embodiments of the present disclosure has a compressive strength of more than 2.0 MPa on the 3rd day and the 7th day, which can fully meet the strength requirement of the filling material of the mined-out area of the mine, and the pH of the leaching liquid of the red mud-based filling paste is less than 9, and the content of the harmful factors in the leaching liquid of the red mud-based filling paste meets the groundwater quality standard (GB14848-2017) of the type III water index, which meets the environmental protection index of the filling of the mined-out area of the mine.

[0265] Compared with the data of each embodiment, the preset temperature of dry activation in Comparative Example 3 is increased to more than 350℃, although the product performance of the obtained red mud-based filling paste is close to that of the embodiments, the dry activation is not in a low-temperature state, which increases the energy consumption of the production equipment.

[0266] Compared with the data of each embodiment, in Comparative Example 5, an excessive amount of adsorbent is added, although the adsorbent can fully play a role, the raw material consumption for preparing the red mud-based filling paste is obviously increased, and the production cost of the red mud-based filling paste is also increased.

[0267] Compared with the data of each embodiment, in Comparative Example 7, an excessive amount of gelling powder is added, although the gelling powder can fully play a gelling role, the raw material consumption of the preparation method is increased, and the production cost of the preparation method is also increased.

[0268] Compared with the data of each embodiment, in Comparative Example 9, an excessive amount of acid activator is added, although the acid activator can fully play an activation role, the raw material consumption of the preparation method is increased, and the production cost of the preparation method is also increased.

[0269] Compared with the data of each embodiment, in the technical solution disclosed in Comparative Example 4, no adsorbent is added, and the compressive strength of the obtained red mud-based filling paste is similar, but the content of the harmful factors in the leaching liquid of the obtained red mud-based filling paste is large, which is difficult to be continuously applied.

[0270] Compared with the related art, in the case that the red mud-based filling paste prepared by the preparation method of the red mud-based filling paste disclosed in the embodiments of the present disclosure meets the material performance requirement of the filling of the mined-out area of the mine, the total doping amount of the red mud in the preparation method can be as high as 75%, which can realize the large-scale consumption of the red mud, reduce the filling cost of the cemented filling mining method on the premise of solving the environmental hidden danger of the red mud storage, and help the sustainable development of enterprises.

[0271] In summary, the preparation method of the red mud-based filling paste according to some embodiments of the present disclosure has the following advantages compared with the related art:

[0272] The preparation method of the red mud-based filling paste according to some embodiments of the present disclosure can avoid the addition of cement while improving the conversion rate of the Bayer process red mud into the filling paste, so as to reduce the cost of the red mud as the filling material.

[0273] The preparation method of the red mud-based filling paste according to some embodiments of the present disclosure can activate the cementitious components of the red mud in the ground powder and the adsorption performance of the adsorbent based on the dry activation at the medium or low temperature, and the activated adsorbent can adsorb the red mud and the industrial solid waste together through the adsorption, and then the red mud and the industrial solid waste can be cemented and combined through the cementation of the activated red mud, so as to obtain the cemented powder material. The activated adsorbent can also inhibit the migration of the heavy metal ions in the industrial solid waste and the red mud, so as to avoid the damage of the migration of the heavy metal ions to the cementation of the activated red mud, so as to obtain the cemented powder material with good cementation performance. Then, the cemented powder material, the Bayer process red mud and the aggregate are mixed to obtain the pre-filling dry material. The Bayer process red mud and the aggregate can be preliminarily cemented together through the cemented powder material with good cementation performance. The high strength of the aggregate can be used to improve the strength of the filling paste. Finally, the pre-filling dry material, the acid activator, the water reducing agent and water are mixed. The pre-filling dry material and the acid activator are dispersed through the dispersion of water, so as to facilitate the uniform mixing between the pre-filling dry material and the acid activator. The acid activator can activate the cementation of the cemented powder material in the pre-filling dry material through the activation, so as to further cement the Bayer process red mud and the aggregate in the pre-filling dry material completely, and facilitate the improvement of the compressive strength of the filling paste through the high strength of the aggregate. In addition, the acid activator can react with the alkaline components in the mixed red mud components composed of the red mud and the Bayer process red mud through the acid-base neutralization reaction, so as to improve the compressive strength of the filling paste while reducing the amount of the solid alkali agent. In addition, the addition of the water reducing agent can reduce the water content of the filling paste, promote the complete formation of the filling paste, and form the colloidal components in the water. The colloidal material can improve the cementation strength of the cemented powder material, so as to improve the compressive strength of the filling paste.

[0274] The above only describes the specific embodiments of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined in the present disclosure can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments shown in the present disclosure, but will conform to the widest scope consistent with the principles and novel features disclosed in the present disclosure.

Claims

1. A method for preparing a red mud-based filling paste, comprising: grinding and mixing industrial solid waste, adsorbent and red mud to obtain a ground powder; dry-activating the ground powder at a preset temperature to activate the cementitious component of the red mud and the adsorption performance of the adsorbent in the ground powder, to obtain a cementitious powder; mixing Bayer red mud, aggregate and the cementitious powder to obtain a pre-filling dry mixture with mixed red mud components; and mixing an acid activator, a water reducing agent, water and the pre-filling dry mixture with mixed red mud components to activate the cementitious effect of the mixed red mud components in the pre-filling dry mixture by the acid activator, to obtain a red mud-based filling paste; wherein the preset temperature is ≤350℃. The red mud comprises Bayer red mud and / or sintered red mud.

2. The production method according to claim 1, wherein, The preset temperature is 120℃-350℃, and the dry-activation time is 10min-60min.

3. The production method according to claim 1, wherein, The components of the ground powder satisfy, in terms of weight fraction:

4. The production method according to claim 1, wherein red mud: 10-50 parts, industrial solid waste: 40-80 parts and adsorbent: 1-10 parts. The industrial solid waste comprises at least two of:

5. The production method according to any one of claims 1 to 4, characterized by fly ash, slag powder, slag, carbide slag and desulfurization gypsum; and / or, The adsorbent comprises at least one of: montmorillonite, sepiolite and diatomite. The particle size of the ground powder is <178μm. The components of the pre-filling dry mixture comprise, in terms of weight fraction:

6. The production method according to claim 1, wherein cementitious powder: 10-30 parts, Bayer red mud: 20-60 parts and aggregate: 0-80 parts; and / or, 7. The production process according to any one of claims 1 to 4, wherein The aggregate comprises at least one of: crushed stone, tailings and slag. The weight m1 of the acid activator and the weight m2 of the pre-filling dry mixture satisfy the relationship: m1:m2=(0.2-2.0):100; The weight m3 of the water reducing agent and the weight m2 of the pre-filling dry mixture satisfy the relationship:

8. The production method according to claim 1, wherein m3:m2=(0.2-1.0):100; and the weight m4 of the water and the total weight m5 of the pre-filling dry mixture, the acid activator and the water reducing agent satisfy the relationship: m4:m5=(0.5-1.0):

1. The acid activator comprises at least one of: acetic acid, phosphoric acid and aluminum dihydrogen phosphate; and / or, The water reducing agent comprises at least one of:

9. The production method according to claim 1, wherein lignin sulfonate, naphthalene-based superplasticizer, polycarboxylate-based water reducing agent and sulfamate water reducing agent. The red mud-based filling paste is obtained by the method of any one of claims 1-9. ​ ​ 10. A red mud based backfill paste, wherein, ​

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