A method for preparing a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body

Abstract

The present invention provides a method for preparing a lithium-doped slag mixed fiber-reinforced cemented lithium feldspar tailings filling body, comprising: step S1, ball-milling and drying fly ash, lithium feldspar tailings, lithium slag, and slag powder; step S2, controlling the mass ratio of cementitious material to filling aggregate to be 1:6, dry-mixing the cementitious material, filling aggregate, slag powder, desulfurized gypsum, polypropylene fiber, and glass fiber for a period of time, then adding water and stirring for a period of time until the polypropylene fiber and glass fiber are fully dispersed, thereby obtaining a slurry; and step S3, pouring the slurry into a mold and curing the mold to obtain the lithium-doped slag mixed fiber-reinforced cemented lithium feldspar tailings filling body. The filling body prepared by the present invention has high strength and high toughness.

Description

Technical Field

[0001] The invention relates to the technical field of filling material preparation, in particular to a method for preparing a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body. Background Art

[0002] With the sharp increase in demand for mineral resources in my country, the mining volume of metal mines has increased dramatically. A large amount of tailings is produced during the mining process, causing tailings accumulation, which can easily lead to safety accidents. After the ore is smelted and refined, lithium slag is also produced. Tailings and lithium slag are both solid wastes. Improper treatment will damage the environment and pollute water sources and soil. Cemented tailings backfill is a commonly used environmentally friendly technology for treating tailings. It can make full use of tailings for backfilling and improve the safety of mine mining. Cemented tailings backfill material is usually made by mixing cement, tailings and water. However, cemented tailings backfill has disadvantages such as low strength and high brittleness, which poses a safety hazard. Many studies have added fiber, straw and rubber to cemented tailings backfill to improve the compressive strength and plasticity of the filling material.

[0003] Compared to tailings, the treatment and disposal costs of lithium slag under traditional methods are higher, and there are technical difficulties, including high temperature and high pressure requirements during the treatment process, as well as the disposal of solid waste after treatment. The activity of lithium slag particles is higher than that of tailings particles, and the filling body obtained by reaction with cementitious materials has higher strength. This method uses fly ash to replace part of the cement, saving cement costs, and replaces tailings with part of lithium slag to improve the utilization rate of tailings and lithium slag. Since the addition of fibers will reduce the fluidity of the slurry, the fiber content cannot be too high. Based on this, an appropriate amount of slag powder and desulfurized gypsum powder is added to improve the fluidity of the slurry and further improve the strength of the filling body. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a high-strength and high-toughness lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body, which, on the one hand, makes full use of tailings and lithium slag (i.e., waste residue after lithium extraction from lithium feldspar), and on the other hand, saves costs by adding fly ash to replace part of the cement, where lithium slag is the waste residue after lithium extraction from lithium feldspar. Slag powder, desulfurized gypsum powder and mixed fiber ensure the compressive strength and toughness of the filling body. By preparing filling bodies with different tailings and lithium slag mass ratios, ordinary silicate and fly ash mass ratios, and different polypropylene fiber and glass fiber content ratios, a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body with the best strength and toughness improvement effect is obtained.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body, comprising:

[0007] Step S1, ball-milling and drying fly ash, lithium feldspar tailings, lithium slag, and slag powder respectively;

[0008] Step S2, controlling the mass ratio of cementitious material (ordinary Portland cement and fly ash) to filling aggregate (lithium feldspar tailings and lithium slag) to be 1:6, and dry-mixing the cementitious material, filling aggregate, polypropylene fiber and glass fiber, slag powder, and desulfurized gypsum according to the number of parts for a period of time, and then adding water and stirring for a period of time until the polypropylene fiber and glass fiber are fully dispersed to obtain a slurry;

[0009] Step S3: pouring the slurry into a mold and curing the mold to obtain a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body.

[0010] The raw material ratio is controlled to be: polypropylene fiber: glass fiber: cement: fly ash: lithium feldspar tailings: lithium slag: slag powder: desulfurized gypsum: water = 1-3: 1-3: 57.1: 38.1: 95.2-476.2: 95.2-476.2: 95.2: 19: 420.5. The ratio is by mass.

[0011] The slurry concentration was 65%.

[0012] Optionally, in step S1, the ball mill speed is 150 rpm to 250 rpm, the ball milling is performed for 4 to 8 hours, and the drying temperature is 100° C. to 110° C. for at least 24 hours.

[0013] Optionally, in step S2, the lengths of the polypropylene fiber and the glass fiber are both 3 mm-12 mm and should be consistent, and the strength of ordinary Portland cement is 42.5.

[0014] Optionally, in step S3, the mold is a detachable plastic mold with a diameter of 50 mm and a height of 100 mm, the temperature of the curing box is 20±1° C., the curing humidity is 95%±5%, and the curing time is 28 days.

[0015] Optionally, the total content of polypropylene fiber and glass fiber is 0.60% of the sum of the contents of cementitious material and filling aggregate, and the mass ratio of polypropylene fiber to glass fiber is 1-3:1-3, for example, 1:3, 1:1 and 3:1 can be selected; the optimal ratio of raw materials is a ratio of polypropylene fiber to glass fiber of 3:1, that is, the polypropylene fiber content is 0.45%, the glass fiber content is 0.15%, the mass ratio of fly ash to cement is 1:2, the mass ratio of lithium slag to lithium feldspar tailings is 1:2, the mass of slag powder is one-sixth of the filling aggregate, and the mass of desulfurized gypsum is 20% of the cementitious material.

[0016] Optional, the unevenness coefficient C of ordinary Portland cement, fly ash, desulfurized gypsum powder, lithium feldspar tailings, lithium slag and slag powder u and the curvature coefficient Cc Satisfy C respectively u >5 and 1<C c <3; ordinary Portland cement strength grade is 42.5; harmful oxides in lithium slag meet the requirements.

[0017] Optionally, a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body is used in space filling.

[0018] The lithium feldspar tailings and lithium slag used in the present invention are from a mine in Yichun, Jiangxi Province, and the ordinary Portland cement, fly ash, slag powder, desulfurized gypsum powder, polypropylene fiber and glass fiber used are purchased from merchants.

[0019] The maximum compressive strength and stress-strain curve of the filling specimens were obtained through uniaxial compression tests. The stress-strain curve was converted into a load-deflection curve, and the toughness of the filling was quantified based on the area of ​​the load-deflection curve after the peak load.

[0020] Preparation of a high-strength, high-toughness, lithium-doped slag-reinforced fiber-reinforced cemented lithium feldspar tailings backfill: The mass ratio of cementitious material to filler aggregate was constant at 1:6, the mass ratio of ordinary Portland cement to fly ash was 2:1, and the mass ratios of lithium feldspar tailings to lithium slag were 1:5, 1:2, 1:1, 2:1, and 5:1, respectively. The mass of slag powder accounted for one-sixth of the filler aggregate, and desulfurized gypsum powder accounted for 20% of the cementitious material mass. In the fiber-reinforced lithium feldspar tailings-lithium slag backfill, the polypropylene fiber and glass fiber contents were 0.15% and 0.45%, 0.3% and 0.3%, and 0.45% and 0.15%, respectively, of the combined cementitious material and filler aggregate contents. Fiber lengths ranged from 3 mm to 12 mm. The cementitious material, filler aggregate, and fibers were dry-mixed in a cement mortar mixer for 3 to 5 minutes. Water was then added and stirred for an additional 3 to 5 minutes until the fibers were completely dispersed. The slurry was then poured into a cylindrical mold with a mold size of 50 mm in diameter and 100 mm in height.

[0021] Uniaxial compression test of the filling body: The curing time is 28 days. After the curing is completed, the sample surface is first polished to meet the flatness requirements. Then, the filling body samples used are subjected to uniaxial compression test. The stress-strain mode of the MTS universal testing machine is used, and the loading rate is 0.5mm / min. The maximum compressive strength and stress-strain curve of the entire process are recorded. The stress-strain curve is converted into a load-deflection curve. The toughness of the filling body is quantified based on the area of ​​the load-deflection curve. The compressive strength and toughness of the mixed fiber reinforced cemented lithium feldspar tailings filling body with different lithium-doped slags are compared with the blank control group. Three filling bodies of each type are prepared, and the average compressive strength and toughness are taken.

[0022] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0023] In the method for preparing a high-strength and high-toughness lithium-doped slag mixed fiber-reinforced cemented lithium feldspar tailings filling body provided by the present invention, fly ash is used to replace part of the cement, so that the filling body structure is more compact and durable, while saving cement costs; the added desulfurization gypsum and slag powder can improve the fluidity of the slurry after adding the mixed fiber, thereby improving the processability and transportability of the filling body; the lithium slag particles are more active and more conducive to the hydration reaction of cement, and using an appropriate amount of lithium slag to replace part of the tailings can improve the strength of the filling body; different fibers have different properties, and polypropylene fiber does not contribute as much to strength as glass fiber, but its improvement in toughness is significantly greater than that of glass fiber. Adding different amounts of mixed fibers enhances the compressive strength and toughness of the filling body, thereby transforming its brittleness into plasticity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 Schematic diagram of the preparation method of the present invention; DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.

[0027] Example 1

[0028] After ball-milling and drying fly ash, feldspar tailings, lithium slag, and slag powder, 1 part polypropylene fiber and 3 parts glass fiber were mixed in a cementitious material to filler aggregate ratio of 1:6. 57.1 parts of ordinary Portland cement, 38.1 parts of fly ash, 95.2 parts of feldspar tailings, 476.2 parts of lithium slag, 95.2 parts of slag powder, and 19 parts of desulfurized gypsum were dry-mixed in a cement mortar mixer for 3-5 minutes. 420.5 parts of water were then added and stirred for another 3-5 minutes until the fibers were fully dispersed. The slurry was then poured into a cylindrical mold measuring 50 mm in diameter and 100 mm in height. After pouring, the mold was placed in a standard curing chamber under the following conditions: curing temperature of 20 ± 1°C, curing humidity of 95 ± 5%, and curing time of 28 days. A lithium slag-doped fiber-reinforced cemented feldspar tailings fill was prepared according to the above steps and subjected to uniaxial compression testing.

[0029] Example 2

[0030] According to the steps of Example 1, only the lithium feldspar tailings were changed to 190.4 parts and the lithium slag was changed to 381 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0031] Example 3

[0032] According to the steps of Example 1, only the lithium feldspar tailings and lithium slag were changed to 285.7 parts, and the lithium slag was changed to 285.7 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0033] Example 4

[0034] According to the steps of Example 1, only the lithium feldspar tailings were changed to 381 parts and the lithium slag was changed to 190.4 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0035] Example 5

[0036] According to the steps of Example 1, only the lithium feldspar tailings were changed to 476.2 parts and the lithium slag was changed to 95.2 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0037] Example 6

[0038] Following the steps of Example 1, except that the proportions of polypropylene fiber and glass fiber were both changed to 2 parts, a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body was prepared, and a uniaxial compression test was performed.

[0039] Example 7

[0040] According to the steps of Example 6, only the lithium feldspar tailings were changed to 190.4 parts and the lithium slag was changed to 381 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0041] Example 8

[0042] According to the steps of Example 6, only the lithium feldspar tailings and lithium slag were changed to 285.7 parts, and the lithium slag was changed to 285.7 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0043] Example 9

[0044] According to the steps of Example 6, only the lithium feldspar tailings were changed to 381 parts and the lithium slag was changed to 190.4 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0045] Example 10

[0046] According to the steps of Example 6, only the lithium feldspar tailings were changed to 476.2 parts and the lithium slag was changed to 95.2 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0047] Example 11

[0048] Following the steps of Example 1, except that the proportions of polypropylene fiber and glass fiber were changed to 3 parts and 1 part respectively, a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body was prepared, and a uniaxial compression test was carried out.

[0049] Example 12

[0050] According to the steps of Example 11, only the lithium feldspar tailings were changed to 190.4 parts and the lithium slag was changed to 381 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0051] Example 13

[0052] According to the steps of Example 11, only the lithium feldspar tailings and lithium slag were changed to 285.7 parts, and a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body was prepared, and a uniaxial compression test was carried out.

[0053] Example 14

[0054] According to the steps of Example 11, only the lithium feldspar tailings were changed to 381 parts and the lithium slag was changed to 190.4 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0055] Example 15

[0056] According to the steps of Example 11, only the lithium feldspar tailings were changed to 476.2 parts and the lithium slag was changed to 95.2 parts to prepare a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0057] Example 16

[0058] According to the steps of Example 11, except that no fiber was added, a non-fiber-reinforced cemented lithium feldspar tailings filling body of lithium-doped slag was prepared, and a uniaxial compression test was carried out.

[0059] Example 17

[0060] According to the steps of Example 16, only the lithium feldspar tailings were changed to 190.4 parts and the lithium slag was changed to 381 parts to prepare a lithium slag-doped fiber-free reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0061] Example 18

[0062] According to the steps of Example 16, only the lithium feldspar tailings and lithium slag were changed to 285.7 parts, and the lithium feldspar tailings filling body without fiber reinforcement and cementation was prepared, and a uniaxial compression test was carried out.

[0063] Example 19

[0064] According to the steps of Example 16, only the lithium feldspar tailings were changed to 381 parts and the lithium slag was changed to 190.4 parts to prepare a lithium slag-doped fiber-free reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0065] Example 20

[0066] According to the steps of Example 16, only the lithium feldspar tailings were changed to 476.2 parts and the lithium slag was changed to 95.2 parts to prepare a lithium slag-doped fiber-free reinforced cemented lithium feldspar tailings filling body, and a uniaxial compression test was carried out.

[0067] The high-strength and high-toughness lithium-doped slag mixed fiber-reinforced cemented lithium feldspar tailings filling body prepared in the above embodiment was subjected to a uniaxial compressive test at a loading rate of 0.5 mm / min in an MTS electronic universal testing machine with a maximum rated force of 30 kN. The results are shown in Table 1:

[0068] Table 1 Uniaxial compression test results of lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling

[0069] Test items Compressive strength / MPa toughness Test items Compressive strength / MPa toughness Example 1 4.65 2.35 Example 11 5.17 4.53 Example 2 4.99 2.47 Example 12 5.74 4.59 Example 3 5.53 2.53 Example 13 6.33 4.62 Example 4 5.87 2.79 Example 14 6.81 4.73 Example 5 5.68 2.61 Example 15 6.45 4.65 Example 6 4.89 3.15 Example 16 2.65 1.00 Example 7 5.13 3.28 Example 17 3.01 1.06 Example 8 5.52 3.49 Example 18 3.35 1.14 Example 9 6.11 3.66 Example 19 3.70 1.21 Example 10 5.78 3.53 Example 20 3.55 1.17

[0070] To quantify the toughness of the backfill specimens, the toughness of Example 16 was assigned a value of 1.00. The hybrid fiber-reinforced lithium-doped slag-cemented lithium feldspar tailings backfill prepared according to the above method exhibits significant compressive strength and toughness, effectively fulfilling its filling function. This improves the utilization of tailings and lithium slag while significantly enhancing the safety of underground backfill.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body, characterized in that: include: Step S1, ball-milling and drying fly ash, lithium feldspar tailings, lithium slag, and slag powder respectively; Step S2: The mass ratio of the cementitious material to the filling aggregate is 1:

6. The cementitious material, the filling aggregate, the polypropylene fiber and the glass fiber, the slag powder, and the desulfurized gypsum are first dry-mixed for a period of time, and then water is added and stirred for a period of time until the polypropylene fiber and the glass fiber are fully dispersed to obtain a slurry; Step S3, pouring the slurry into a mold and curing it to obtain a lithium slag-doped mixed fiber reinforced cemented lithium feldspar tailings filling body; wherein the raw material ratio is: polypropylene fiber: glass fiber: cement: fly ash: lithium feldspar tailings: lithium slag: slag powder: desulfurized gypsum: water = 1-3: 1-3: 57.1: 38.1: 95.2-476.2: 95.2-476.2: 95.2: 19: 420.5; the slurry concentration is 65%; In step S2, the cementitious materials are ordinary Portland cement and fly ash, and the filling aggregates are lithium feldspar tailings and lithium slag.

2. The method according to claim 1, characterized in that In step S1, the ball mill speed is 150r / min-250r / min, the ball milling is 4-8h, the drying temperature is 100C-110°C, and the drying time is not less than 24h.

3. The method according to claim 1, characterized in that In step S2, the lengths of the polypropylene fiber and the glass fiber are both 3 mm to 12 mm and should be consistent, the strength of ordinary Portland cement is 42.5, and the dry mixing time and the water adding and stirring time are both 3 to 5 minutes.

4. The method according to claim 1, wherein In step S3, the mold is a detachable plastic mold with a diameter of 50 mm and a height of 100 mm. The curing temperature of the curing box is 20±1°C, the curing humidity is 95±5%, and the curing time is 28 days.

5. The method according to claim 1, wherein The total content of the polypropylene fiber and the glass fiber is 0.60% of the total content of the cementitious material and the filling aggregate, and the mass ratio of the polypropylene fiber to the glass fiber is 1-3:1-3.

6. The method according to claim 5, characterized in that The mass ratio of polypropylene fiber to glass fiber is 3:1, the mass ratio of fly ash to cement is 1:2, the mass ratio of lithium slag to lithium feldspar tailings is 1:2, the mass of slag powder is one-sixth of the filling aggregate, and the mass of desulfurized gypsum is 20% of the cementitious material.

7. The method according to claim 1, characterized in that The unevenness coefficient Cu and curvature coefficient Cc of ordinary Portland cement, fly ash, desulfurized gypsum powder, lithium feldspar tailings, lithium slag and slag powder satisfy Cu>5 and 1<Cc<3 respectively.

8. Use of a lithium-doped slag mixed fiber reinforced cemented lithium feldspar tailings filling body prepared by the method according to any one of claims 1 to 7 in space filling.

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