Low-carbon and environment-friendly solid waste filling material for mine filling and preparation method thereof

Abstract

The application relates to the technical field of building materials, and particularly relates to a low-carbon and environment-friendly solid waste filling material for mine filling and a preparation method thereof.The low-carbon and environment-friendly solid waste filling material for mine filling comprises 2-15 wt.% of cementing material, 0-5 wt.% of fly ash and 0-90 wt.% of tailing sand in percentage of mass, and the cementing material comprises 1-3 wt.% of high calcium oxide-belite cementing material, 2-5 wt.% of sulphate aluminate cement clinker, 70-80 wt.% of slag and 15-25 wt.% of anhydrite.The low-carbon and environment-friendly solid waste filling material for mine filling is obtained by synergistic action of cement clinker, slag, anhydrite, fly ash and tailing sand, has a fast coagulation and hardening rate, meets the strength requirement of a filling body, has a small cement clinker usage amount, a large solid waste usage proportion and low comprehensive cost.

Description

Technical Field

[0001] This invention relates to the technical field of building materials, specifically to a low-carbon and environmentally friendly solid waste backfill material for mine backfilling and its preparation method. Background Technology

[0002] Mineral resources are vital natural resources and an essential material foundation for social production and development, playing an indispensable role in people's lives and work. However, while mineral extraction provides various industrial raw materials, it also generates large amounts of mined-out areas and tailings. Cemented backfill materials, due to their wide availability and ease of use, have become the primary material used in mine backfilling in recent years. Common cemented backfill materials are generally prepared from cementing materials, modified additives, and inert materials. Silicate cement is commonly used as the cementing material in backfill materials, but it suffers from high cost, low strength, slow setting and hardening rate, and severe segregation and bleeding of the slurry, making it difficult to meet the requirements of mine backfilling.

[0003] With technological advancements, patent document CN202210679055 has emerged, which utilizes all-solid-waste preparation for backfill materials. However, without using any cement clinker, the mortar strength of the cementitious material prepared in this way is very low in both early and later stages. Even after increasing the amount of cementitious material used and employing inorganic or organic dispersing water-reducing agents when preparing concrete, it is still difficult to achieve satisfactory filling strength. Further improving the utilization rate of cemented backfill materials, controlling their cost, and recycling tailings are the main directions for the future development of cemented backfill materials. Therefore, it is urgent to develop a new type of low-carbon and environmentally friendly solid waste backfill material for mine backfilling. Summary of the Invention

[0004] This invention proposes a low-carbon and environmentally friendly solid waste backfill material for mine backfilling and its preparation method, in order to solve the problems of high cost, low strength, slow setting and hardening rate, and serious slurry segregation and bleeding in the existing technology, which make it difficult to meet the requirements of mine backfilling.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A low-carbon and environmentally friendly solid waste backfill material for mine backfilling, comprising the following components by weight percentage:

[0007] Cementitious materials: 2-15 wt.%;

[0008] Fly ash 0-5 wt.%;

[0009] Tailings sand 70-90 wt.%;

[0010] And the percentage by weight of the above components:

[0011] Water-reducing agent 0.1–0.3 wt.%;

[0012] Water-retaining agent 0.1–0.3 wt.%;

[0013] The cementitious material comprises the following components by weight percentage: 1-3 wt.% high-calcium oxide-belite cementitious material, 2-5 wt.% sulfoaluminate cement clinker, 70-80 wt.% slag, and 15-25 wt.% anhydrite.

[0014] Furthermore, the slag comprises the following components by mass percentage: 25-60 wt.% blast furnace slag, 15-30 wt.% titanium slag, and 0-30 wt.% ferrosilicon manganese slag.

[0015] Furthermore, the specific surface area of ​​the slag is >420 m². 2 / kg.

[0016] Furthermore, the mineral composition of the high-calcium oxide-belite cementitious material includes: f~CaO 25~34wt.%, C2S 25~35wt.%, C3S 8~16wt.%, CaSO4 3~7wt.%.

[0017] Furthermore, the high-calcium oxide-belite cementitious material is calcined at 1300–1350°C.

[0018] Furthermore, the specific surface area of ​​the high-calcium oxide-belite cementitious material is 380–420 m². 2 / kg.

[0019] Furthermore, the mineral composition of the sulfoaluminate cement clinker contains >45 wt.% anhydrous calcium sulfoaluminate and >70 wt.% dicalcium silicate.

[0020] Furthermore, the fly ash is Class II fly ash with a specific surface area of ​​400–450 m². 2 / kg.

[0021] Furthermore, the tailings sand is one or more of quartz tailings sand, graphite tailings sand, iron tailings sand, copper tailings sand, and gold tailings sand, and the moisture content of the tailings sand is ≤1% and the median particle size is ≤0.2mm.

[0022] The present invention also provides a method for preparing a low-carbon and environmentally friendly solid waste backfill material for mine backfilling. The method involves weighing out the cementitious material, fly ash, tailings sand, water-reducing agent and water-retaining agent and mixing them into a dry material. The dry material is then uniformly mixed with water to obtain the low-carbon and environmentally friendly solid waste backfill material for mine backfilling. The mass ratio of dry material to water is 1:(0.25~0.4).

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) This invention utilizes the synergistic effect of cement clinker, slag, anhydrite, fly ash, and tailings sand to obtain a low-carbon and environmentally friendly solid waste backfill material for mine backfilling. It has a fast setting and hardening rate and its strength meets the requirements of the backfill body.

[0025] (2) The present invention uses less cement clinker, has a high proportion of solid waste, and has a low overall cost.

[0026] (3) The present invention uses less cement clinker and has low carbon emissions. It can consume waste residue and tailings sand, thus alleviating resource and environmental pressures. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] The slag used in this embodiment of the invention has a specific surface area > 420 m². 2 / kg.

[0029] The high-calcium oxide-belite cementitious material used in the embodiments of the present invention is calcined at 1300-1350°C.

[0030] The high-calcium oxide-belite cementitious material used in the embodiments of this invention has a specific surface area of ​​380-420 m². 2 / kg.

[0031] The mineral composition of the sulfoaluminate cement clinker used in this embodiment of the invention contains >45 wt.% anhydrous calcium sulfoaluminate and >70 wt.% dicalcium silicate.

[0032] The fly ash used in this embodiment of the invention is Class II fly ash with a specific surface area of ​​400-450 m². 2 / kg.

[0033] Example 1

[0034] As a preferred embodiment of the present invention, the specific composition of a low-carbon and environmentally friendly solid waste backfill material for mine backfilling disclosed in this embodiment is shown in Table 1.

[0035] Table 1

[0036] Components Weight percentage (wt.%) cementing materials 10.5 fly ash 4.5 Graphite tailings 85

[0037] This embodiment also includes 0.2 wt.% water-reducing agent and 0.2 wt.% water-retaining agent, which account for the total weight percentage of the components in Table 1.

[0038] In this embodiment, the tailings sand is graphite tailings sand.

[0039] In this embodiment, the cementitious material comprises the following components by weight percentage: 2 wt.% high-calcium oxide-belite cementitious material, 5 wt.% sulfoaluminate cement clinker, 78 wt.% slag, and 15 wt.% anhydrite.

[0040] In this embodiment, the slag comprises the following components by weight percentage: 51 wt.% blast furnace slag, 22 wt.% titanium ore slag, and 27 wt.% ferrosilicon manganese slag.

[0041] In this embodiment, the minerals in the high-calcium oxide-belite cementitious material include: f~CaO 30.8wt.%, C2S 29.1wt.%, C3S 12.9wt.%, CaSO4 5.3wt.%.

[0042] Weigh out the cementitious materials, fly ash, tailings sand, water-reducing agent and water-retaining agent according to Table 1 and mix them into dry material. Mix the dry material with water evenly to obtain solid waste filling material 1#. The mass ratio of dry material to water is 1:0.3.

[0043] Example 2

[0044] As a preferred embodiment of the present invention, the specific composition of a low-carbon and environmentally friendly solid waste backfill material for mine backfilling disclosed in this embodiment is shown in Table 2.

[0045] Table 2

[0046] Components Weight percentage (wt.%) cementing materials 10 fly ash 5 Graphite tailings 85

[0047] This embodiment also includes 0.2 wt.% water-reducing agent and 0.2 wt.% water-retaining agent, which account for the total weight percentage of the components in Table 2.

[0048] In this embodiment, the tailings sand is graphite tailings sand.

[0049] In this embodiment, the cementitious material comprises the following components by weight percentage: 2 wt.% high-calcium oxide-belite cementitious material, 5 wt.% sulfoaluminate cement clinker, 78 wt.% slag, and 15 wt.% anhydrite.

[0050] In this embodiment, the slag comprises the following components by weight percentage: 51 wt.% blast furnace slag, 22 wt.% titanium ore slag, and 27 wt.% ferrosilicon manganese slag.

[0051] In this embodiment, the minerals in the high-calcium oxide-belite cementitious material include: f~CaO 30.8wt.%, C2S 29.1wt.%, C3S 12.9wt.%, CaSO4 5.3wt.%.

[0052] Weigh out the cementitious materials, fly ash, tailings sand, water-reducing agent and water-retaining agent according to Table 2 and mix them into dry material. Mix the dry material with water evenly to obtain solid waste filling material 2#. The mass ratio of dry material to water is 1:0.29.

[0053] Example 3

[0054] As a preferred embodiment of the present invention, the specific composition of a low-carbon and environmentally friendly solid waste backfill material for mine backfilling disclosed in this embodiment is shown in Table 3.

[0055] Table 3

[0056]

[0057]

[0058] This embodiment also includes 0.2 wt.% water-reducing agent and 0.2 wt.% water-retaining agent, which account for the total weight percentage of the components in Table 3.

[0059] In this embodiment, the tailings sand is gold tailings sand.

[0060] In this embodiment, the cementitious material comprises the following components by weight percentage: 2 wt.% high-calcium oxide-belite cementitious material, 5 wt.% sulfoaluminate cement clinker, 78 wt.% slag, and 15 wt.% anhydrite.

[0061] In this embodiment, the slag comprises the following components by weight percentage: 44 wt.% blast furnace slag, 30 wt.% titanium slag, and 26 wt.% ferrosilicon manganese slag.

[0062] In this embodiment, the minerals in the high-calcium oxide-belite cementitious material include: f~CaO 30.8wt.%, C2S 29.1wt.%, C3S 12.9wt.%, CaSO4 5.3wt.%.

[0063] Weigh out the cementitious materials, fly ash, tailings sand, water-reducing agent and water-retaining agent according to Table 3 and mix them into dry material. Mix the dry material with water evenly to obtain solid waste filling material 3#. The mass ratio of dry material to water is 1:0.31.

[0064] Comparative Example 1

[0065] In this comparative example, except that the cementing material does not contain high-calcium oxide-Belit cementing material, everything else is the same as in Example 2, resulting in solid waste backfill material 4#.

[0066] In this comparative example, the cementitious materials included 7 wt.% sulfoaluminate cement clinker, 78 wt.% slag, and 15 wt.% anhydrite.

[0067] Comparative Example 2

[0068] In this comparative example, except that the cementitious material does not contain sulfoaluminate cement clinker, everything else is the same as in Example 3, resulting in solid waste backfill material #5.

[0069] In this comparative example, the cementing materials included 7 wt.% high-calcium oxide-Beilite cementitious material, 78 wt.% slag, and 15 wt.% anhydrite.

[0070] The solid waste backfill materials of Examples 1-3 and Comparative Examples 1-2 were tested according to the methods in JGJ / T 70-2009 "Standard for Test Methods of Basic Performance of Building Mortar" and NB / T 51070-2017 "Test Methods of Coal Mine Paste Backfill Materials". The results are shown in Table 4 below.

[0071] Table 4

[0072]

[0073] As shown in Table 4 above, the low-carbon and environmentally friendly solid waste backfill material for mine backfilling provided by this invention, through comparison of the data of Example 2 and Comparative Example 1, shows that the cementitious material in Comparative Example 1 did not contain high-calcium oxide-belite cementitious material, and the activating effect of Comparative Example 1 was weaker than that of Example 2. The mechanical properties of the solid waste backfill material prepared in Example 2 were all better than those of Comparative Example 1. Through comparison of Example 3 and Comparative Example 2, it can be seen that the cementitious material in Comparative Example 2 did not contain sulfoaluminate cement clinker. Due to the high f-CaO content in the high-calcium oxide-belite cementitious material, the hydration process of the solid waste backfill material without sulfoaluminate cement clinker was unfavorable, resulting in insufficient strength.

[0074] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A low-carbon and environmentally friendly solid waste backfill material for mine backfilling, characterized in that, Includes the following components by mass percentage: Cementitious materials 2~15wt.%; Fly ash 4.5~5 wt.%; Tailings sand 70~90wt.%; And the percentage by weight of the above components: Water-reducing agent 0.1~0.3 wt.%; Water-retaining agent 0.1~0.3 wt.%; The cementitious material comprises the following components by weight percentage: 1-3 wt.% high-calcium oxide-belite cementitious material, 2-5 wt.% sulfoaluminate cement clinker, 70-80 wt.% slag, and 15-25 wt.% anhydrite. The minerals in the high-calcium oxide-Beilite cementitious material include: f~CaO 25~34wt.%. 3~10wt.%, C2S25~35wt.%, C3S 8~16wt.%, CaSO4 3~7wt.%; The mineral composition of the sulfoaluminate cement clinker contains >45 wt.% anhydrous calcium sulfoaluminate and >70 wt.% dicalcium silicate. The slag comprises the following components by weight percentage: 25-60 wt.% blast furnace slag, 15-30 wt.% titanium slag, and 0-30 wt.% ferrosilicon manganese slag.

2. The low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to claim 1, characterized in that, The specific surface area of ​​the slag is >420 m². 2 / kg.

3. The low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to claim 1, characterized in that, The high-calcium oxide-Belit gelling material is calcined at 1300~1350℃.

4. A low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to claim 1, characterized in that, The high-calcium oxide-Belit gelling material has a specific surface area of ​​380~420 m². 2 / kg.

5. A low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to claim 1, characterized in that, The fly ash is Class II fly ash with a specific surface area of ​​400~450 m². 2 / kg.

6. The low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to claim 1, characterized in that, The tailings sand is one or more of quartz tailings sand, graphite tailings sand, iron tailings sand, copper tailings sand, and gold tailings sand, with a moisture content ≤1% and a median particle size ≤0.2mm.

7. A method for preparing a low-carbon and environmentally friendly solid waste backfill material for mine backfilling according to any one of claims 1 to 6, characterized in that, Weigh out the cementitious materials, fly ash, tailings sand, water-reducing agent, and water-retaining agent and mix them into a dry material. Mix the dry material with water evenly to obtain the low-carbon and environmentally friendly solid waste backfill material for mine backfilling. The mass ratio of dry material to water is 1:(0.25~0.4).

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