Preparation method of composite activated solid waste-based cemented lepidolite ultrafine tailings filling material

Abstract

The present invention provides a method for preparing a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material, which belongs to the technical field of tailings filling. The method firstly mixes lithium slag, steel slag, desulfurized gypsum, wollastonite powder, water glass, etc. in proportion, and then puts the mixture into a high-temperature and high-pressure reactor set under autoclave conditions for autoclave activation, drying, grinding, and mixing with cement to obtain a composite activated solid waste-based cementitious material; then the lepidolite ultrafine tailings are mixed with the composite activated solid waste-based cementitious material, and tap water is added to form a filling slurry. The present invention can effectively improve the problems of low compressive strength, poor slurry fluidity and large amount of cementitious material in cemented ultrafine tailings. Especially in the context of the growing demand for lithium resources, the present invention has good economic benefits and carbon emission reduction benefits, and is one of the effective ways to comprehensively utilize the solid waste materials generated by lithium resource ore mining and industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of tailings filling, and in particular to a method for preparing a composite activated solid waste-based cemented lepidolite ultrafine grain tailings filling material. Background Art

[0002] With the booming development of science and technology and global energy, the widespread application of lithium resources has become a hot topic today. However, the continuous growth of the lithium mining industry has also brought with it increasingly prominent challenges, particularly the disposal of tailings generated during the mining and processing of lepidolite ore. Currently, underground mines, especially small and medium-sized mines, classify the tailings generated during mining. The coarse tailings after classification are first used for underground backfill, while the remaining ultrafine tailings are stored in tailings ponds. At the same time, with the increasing intensity of mineral resource extraction, high-grade resources are decreasing. To obtain more mineral resources, the demand for finer ore particle size is increasing. High-efficiency grinding technology also leads to the production of large quantities of ultrafine tailings. Due to their small particle size and large specific surface area, ultrafine tailings can easily affect the stability of tailings dams, resulting in "dangerous reservoirs" and incurring considerable storage costs for mines.

[0003] Currently, the most common method for treating ultrafine tailings is to fill the tailings with cement-bound fine-grained tailings. However, the economic benefits of backfill mining are largely determined by the binder material used in the backfill. The cost of cement in cement-based backfill accounts for approximately 70% of the total backfill cost, becoming a key factor limiting this method. Furthermore, relevant research has shown that cement has disadvantages for bonding fine-grained tailings, including poor bonding ability, low filling strength, and high hydration heat. Furthermore, the carbon dioxide generated by the production and use of the cement industry is one of the largest sources of carbon dioxide globally, which also has a certain impact on the environment. Summary of the Invention

[0004] In order to overcome the problems of the prior art in cementing ultrafine lepidolite tailings, the present invention provides a method for preparing a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material, which meets the strength requirements of the cemented filling body and realizes safe, efficient and low-cost mining.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0006] A method for preparing a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material comprises the following steps:

[0007] S1. Evenly mix lithium slag, steel slag, desulfurized gypsum, wollastonite powder, and sodium silicate to obtain a mixed raw material;

[0008] S2, placing the mixed raw material obtained in step S1 into a high-temperature and high-pressure reactor for autoclaving and activation;

[0009] S3, placing the autoclaved activated mixed raw material into a drying oven for drying, and then grinding it in a planetary ball mill;

[0010] S4. The ground mixed raw materials are placed on an ultrasonic vibration screening sieve, and the sieve underflow is added with cement to form a composite activated solid waste-based cementitious material;

[0011] S5. Mix the ultrafine lepidolite tailings with the composite activated solid waste-based gelling material obtained in step S4, add tap water to form a filling slurry, and use it for filling in ore mining pits.

[0012] In the step S1, the lithium slag accounts for 30-40% by mass, the steel slag accounts for 20-30% by mass, the desulfurized gypsum accounts for 15-20% by mass, the wollastonite powder accounts for 5%-10% by mass, and the sodium silicate accounts for 10-15% by mass.

[0013] In step S1, the average particle sizes of lithium slag, steel slag, desulfurized gypsum, wollastonite powder, and sodium silicate are 30-50 μm, 250-300 μm, 40-60 μm, 30-60 μm, and 60-90 μm, respectively;

[0014] The chemical composition of the lithium slag is calculated as follows: SiO2 content is 20-30wt.%, CaO content is 30-40wt.%, Al2O3 content is 15-25wt.%, SO3 content is 5-15wt.%, and loss on ignition is 5-10wt.%;

[0015] The chemical composition of the steel slag is calculated as follows: SiO2 content is 15-25wt.%, CaO content is 40-50wt.%, Al2O3 content is 5-15wt.%, Fe2O3 content is 5-15wt.%, SO3 content is 1-5wt.%, and loss on ignition is 10-15wt.%;

[0016] The purity of CaSO4·2H2O in desulfurized gypsum is greater than 95%wt.%;

[0017] The purity of CaO in the wollastonite powder is greater than 45wt.%, and the purity of SiO2 is greater than 50wt.%;

[0018] The purity of Na2SiO3 in sodium silicate is greater than 90wt.%.

[0019] In step S2, the high-temperature and high-pressure reactor is placed in saturated steam at a temperature not lower than 200° C. and a pressure of 1.2-2.0 MPa, and the mixed raw materials are autoclaved and activated for 4-6 hours.

[0020] In step S3, the drying oven temperature is 80-100°C for 16-24 hours, and the surface is turned over every 8 hours; the planetary ball mill speed is 350r / min-450r / min, and the grinding time is 5-

[0021] 10h.

[0022] In step S4, the ground mixed raw materials are placed on an ultrasonic vibration screening sieve, and the selected specific surface area is controlled to be 550m 2 / kg or more of raw materials; and mix the selected mixed raw materials with cement in a mass ratio of 3:2 to form a composite activated solid waste-based cementitious material.

[0023] In step S5, the ultrafine grains of lepidolite tailings are subjected to classification treatment, and the average characteristic particle size of the ultrafine grains of lepidolite tailings obtained is d 10 d 30 d 60 d 90 They are 5.31μm, 16.92μm, and 40.83μm respectively.

[0024] μm and 145.86μm; -600 mesh ultrafine particles are not less than 50%.

[0025] In step S5, the mass ratio of the ultrafine lepidolite tailings to the composite activated solid waste-based gelling material is 4:1-12:1, and the amount of tap water used ensures that the solid mass fraction of the filling slurry is 55%-65%.

[0026] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0027] The above scheme creates high temperature and high pressure conditions through a high temperature and high pressure reactor, which causes the Si-O and Al-O chemical bonds in the material to break, destroying the stable network structure of the glass body and improving the volcanic ash activity of the material; the material is mechanically ground by a planetary ball mill to optimize the material particle size and specific surface area, further destroying the stable structure of the material glass body while improving the surface activity and adsorption capacity of the material, which helps to improve the interfacial reaction ability of the material and is beneficial to the subsequent hydration reaction of the material; desulfurized gypsum and sodium silicate are used to effectively stimulate the potential activity of steel slag, lithium slag and cement, promoting the formation of early strength and high strength filling; wollastonite powder is used to effectively increase the hydration reaction raw materials in the material, and at the same time, its unique needle-like and fibrous physical structure characteristics effectively enhance the mechanical properties and fire resistance and erosion resistance of the filling; graded treatment effectively solves the adverse effects of ultrafine tailings in traditional lithium mica full tailings treatment; at the same time, the ultrafine lithium mica tailings are used as aggregate to form the filling, which not only meets the actual filling slurry conveying pipeline requirements but also has good working performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 The present invention provides a flow chart for the preparation and application of a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The invention provides a method for preparing a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material.

[0032] like Figure 1 As shown, the preparation method and application include the following steps:

[0033] S1. Evenly mix lithium slag, steel slag, desulfurized gypsum, wollastonite powder, and sodium silicate to obtain a mixed raw material;

[0034] S2, placing the mixed raw material obtained in step S1 into a high-temperature and high-pressure reactor for autoclaving and activation;

[0035] S3, placing the autoclaved activated mixed raw material into a drying oven for drying, and then grinding it in a planetary ball mill;

[0036] S4. The ground mixed raw materials are placed on an ultrasonic vibration screening sieve, and the sieve underflow is added with cement to form a composite activated solid waste-based cementitious material;

[0037] S5. Mixing the ultrafine lepidolite tailings with the composite activated solid waste-based gelling material obtained in step S4, adding tap water to form a filling slurry for underground filling in ore mining.

[0038] The following describes this with reference to specific embodiments.

[0039] Example 1

[0040] according to Figure 1The process shown in the figure is to uniformly mix the following raw materials in a mass fraction ratio: 40% lithium slag, 30% steel slag, 15% desulfurized gypsum, 5% silica fume lime, and 10% sodium silicate; then, the mixed raw materials are placed in saturated steam at a temperature of 250°C and a pressure of 1.2 MPa for 4 hours; then, the mixed raw materials are placed in a drying oven at a temperature of 85°C for 16 hours, and the mixture is turned over every 8 hours during the drying process; finally, the mixture is placed in a planetary ball mill for grinding, and an ultrasonic vibrating screen is used to obtain a specific surface area of ​​550m 2 / kg or more mixed raw materials, the mixed raw materials and PO42.5 cement are mixed in a mass ratio of 3:2 to form a composite activated solid waste-based cementitious material; the graded lithium mica ultrafine tailings are used as aggregate, and the composite activated solid waste-based and pure cement-based cementitious materials are used as cementitious materials to prepare filling bodies with a cementitious material mass fraction of 10%, and the compressive strengths after 7 days, 14 days and 28 days are measured and shown in Table 1 below.

[0041] Table 1

[0042] Examples 7d strength / MPa 14d strength / MPa 28d strength / MPa Composite activated solid waste base 1.15 1.72 2.41 cement-based 0.69 1.13 1.45

[0043] Example 2

[0044] according to Figure 1 The process shown in the figure is to uniformly mix the following raw materials in a mass fraction ratio: lithium slag 40%, steel slag 30%, desulfurized gypsum 15%, silica fume lime 5%, and sodium silicate 10%; then, the mixed raw materials are placed in saturated steam at a temperature of 200°C and 1.4 MPa and autoclaved for 5 hours; then, the mixed raw materials are placed in a drying oven at a temperature of 100°C for 24 hours, and the mixture is turned over every 8 hours during the drying process; finally, the mixture is placed in a planetary ball mill and ground using an ultrasonic vibrating screen to obtain a specific surface area of ​​550 m 2 / kg or more mixed raw materials are mixed with PO42.5 cement in a mass ratio of 3:2 to form a composite activated solid waste-based cementitious material; the lepidolite ultrafine tailings after graded treatment is used as aggregate and the composite activated solid waste base is used as cementitious material to prepare a lepidolite ultrafine tailings filling slurry with a solid mass concentration of 60%, and its slump is measured to be 264mm, which meets the requirements of the actual filling body transportation pipeline on the lithium mine site for the fluidity of the filling slurry.

[0045] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing a composite activated solid waste-based cemented lepidolite ultrafine tailings filling material, characterized in that: The steps are as follows: S1. Evenly mix lithium slag, steel slag, desulfurized gypsum, wollastonite powder, and sodium silicate to obtain a mixed raw material; S2, placing the mixed raw material obtained in step S1 into a high-temperature and high-pressure reactor for autoclaving and activation; S3, placing the autoclaved activated mixed raw material into a drying oven for drying, and then grinding it in a planetary ball mill; S4. The ground mixed raw materials are placed on an ultrasonic vibration screening sieve, and the sieve underflow is added with cement to form a composite activated solid waste-based cementitious material; S5, mixing the ultrafine lepidolite tailings with the composite activated solid waste-based gelling material obtained in step S4, adding tap water to form a filling slurry for filling in ore mining wells; In step S1, the weight ratio of lithium slag is 30-40%, steel slag is 20-30%, desulfurized gypsum is 15-20%, wollastonite powder is 5%-10%, and sodium silicate is 10-15%; In step S4, the selected mixed raw materials are mixed with cement in a mass ratio of 3:2 to form a composite activated solid waste-based cementitious material.

2. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S1, the average particle sizes of lithium slag, steel slag, desulfurized gypsum, wollastonite powder, and sodium silicate are 30-50 μm, 250-300 μm, 40-60 μm, 30-60 μm, and 60-90 μm, respectively; The chemical composition of the lithium slag is calculated as follows: SiO2 content is 20-30wt.%, CaO content is 30-40wt.%, Al2O3 content is 15-25wt.%, SO3 content is 5-15wt.%, and loss on ignition is 5-10wt.%; The chemical composition of the steel slag is calculated as follows: SiO2 content is 15-25wt.%, CaO content is 40-50wt.%, Al2O3 content is 5-15wt.%, Fe2O3 content is 5-15wt.%, SO3 content is 1-5wt.%, and loss on ignition is 10-15wt.%; The purity of CaSO4⋅2H2O in the desulfurized gypsum is greater than 95%wt.; The purity of CaO in the wollastonite powder is greater than 45wt.%, and the purity of SiO2 is greater than 50wt.%; The purity of Na2SiO3 in the sodium silicate is greater than 90wt.%.

3. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S2, the high-temperature and high-pressure reactor is set at a temperature not lower than 200° C. and a gas pressure of 1.2-2.0 MPa saturated steam pressure, and the mixed raw materials are autoclaved and activated for 4-6 hours.

4. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S3, the drying oven is dried at a temperature of 80°C-100°C for 16-24 hours, and the powder is turned over every 8 hours; the planetary ball mill rotates at a speed of 350 r / min-450 r / min for 5-10 hours.

5. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S4, the ground mixed raw materials are placed on an ultrasonic vibration screening sieve, and the selected specific surface area is controlled to be 550m 2 / kg or more of raw materials.

6. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S5, the ultrafine grains of lepidolite tailings are subjected to classification treatment, and the average characteristic particle size of the ultrafine grains of lepidolite tailings obtained is d 10 d 30 d 60 d 90 They are 5.31μm, 16.92μm, 40.83μm and 145.86μm respectively; -600 mesh ultrafine particles are not less than 50%.

7. The method for preparing the composite activated solid waste-based cemented lepidolite ultrafine tailings filling material according to claim 1, characterized in that: In step S5, the mass ratio of the ultrafine lepidolite tailings to the composite activated solid waste-based cementitious material is 4:1-12:1, and the amount of tap water used ensures that the solid mass fraction of the filling slurry is 55%-65%.

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