Preparation method of alkaline-activated tailings powder mine backfill cementitious material

Abstract

The application discloses a preparation method of mine backfill cementing material of alkali-activated tailing powder, and belongs to the technical field of mine backfill materials. The method uses metal mine tailing powder as a main raw material, adopts sodium silicate solution as an alkali activator, and prepares backfill material with excellent cementing characteristics through specific proportioning and stirring, so that the tailing powder is locally recycled. The mass proportion of the components of the cementing material is tailing powder:sodium silicate:water = 1170:154:315. The application activates active silicon, aluminum and other components in the tailing powder through alkali activation, so that the components are converted into hydration products with cementing properties. The cementing material prepared has moderate setting and hardening speed and strength meeting the mine backfill requirements, the raw materials are widely sourced and low in cost, the environmental problems and resource waste problems caused by the storage of the metal mine tailing are solved, and the cementing material has remarkable economic, environmental and social benefits.

Description

Technical Field

[0001] This invention relates to the field of mine backfill materials technology, specifically a method for preparing alkali-activated tailings powder mine backfill cementitious material. Background Technology

[0002] Metal mining generates a large amount of tailings, which are typically disposed of through stockpiling. This not only occupies significant land resources but also poses a serious threat to the ecological environment and the lives and property of nearby residents, potentially leading to landslides, mudslides, soil pollution, and water pollution due to rainwater erosion and seepage. However, tailings also contain elements such as active silicon and aluminum, possessing potential for resource utilization. If these tailings can be transformed into useful materials, it can "turn waste into treasure" and alleviate resource shortages.

[0003] Backfilling of mined-out areas is a crucial means of ensuring safe mine production and reducing geological disasters. Traditional backfill materials often use cement and sand, which are not only costly but also face the problem of increasingly scarce natural sand and gravel resources. In recent years, alkali-activated cementitious materials have received widespread attention due to their advantages such as low carbon footprint, energy saving, and utilization of industrial waste. Alkali-activated cementitious materials activate the active components in industrial waste through alkali activators, causing them to undergo a hydration reaction to generate products with cementing properties, which can replace traditional cement in various engineering fields. However, current research on using alkali activation technology to activate tailings powder from metal mines to prepare mine backfill cementitious materials is limited, and problems such as poor activation effect, insufficient strength of cementitious materials, and unreasonable proportions exist, restricting the large-scale application of tailings powder in mine backfilling.

[0004] Therefore, developing a scientifically formulated, simple to prepare, and high-performance alkali-activated tailings powder backfill cementitious material is of great significance for realizing the resource utilization of tailings, reducing the cost of mine backfilling, and protecting the ecological environment.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the above-mentioned technical defects and provide a method for preparing alkali-activated tailings powder backfill cementitious material. This method uses metal mine tailings powder as the main raw material and sodium silicate solution as the alkali activator. By optimizing the ratio, the active components of the tailings powder are activated to prepare a backfill cementitious material with sufficient strength and stable performance, thereby realizing the on-site backfill utilization of tailings powder.

[0007] To address the aforementioned problems, the present invention provides a method for preparing an alkali-activated tailings powder backfill cementitious material, comprising the following steps: using metal mine tailings powder as the base material and sodium silicate solution as the alkali activator, mixing and stirring in a uniform ratio, and then solidifying and hardening to form a mine backfill cementitious material. The mass ratio of each component of the mine backfill cementitious material is tailings powder: sodium silicate: water = 1170:154:315.

[0008] Preferably, the tailings powder from the metal mine is tailings generated during the mining process of iron mines, copper mines, or lead-zinc mines, with a particle size range of 1-100 μm, wherein the total mass fraction of active SiO2 and Al2O3 is ≥ 50%.

[0009] Preferably, the sodium silicate has a modulus of 2.0-3.0 and a mass fraction of 30%-40%.

[0010] The present invention also discloses a method for preparing alkali-activated tailings powder mine backfill cementitious material by the above method.

[0011] This invention also discloses the application of alkali-activated tailings powder backfill cementitious material in backfilling of mine goaf areas.

[0012] The advantages of this invention compared to existing technologies are: 1. This invention activates active silicon, aluminum and other components in tailings powder through alkali activation, transforming them into hydration products with gelling properties. The prepared gelling material has a moderate setting and hardening speed, and its strength meets the requirements for mine backfilling. Moreover, the raw materials are widely available and inexpensive, effectively solving the environmental and resource waste problems caused by tailings stockpiling in metal mines, and has significant economic, environmental and social benefits. Detailed Implementation

[0013] To make the content of this invention easier to understand, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0014] A method for preparing an alkali-activated tailings powder backfill cementitious material, using metal mine tailings powder as the base material and sodium silicate solution as the alkali activator, is prepared by mixing them in the following mass ratio: tailings powder: sodium silicate: water = 1170:154:315; the specific preparation steps are as follows: Raw material pretreatment: The tailings powder from the metal mine is dried to control its moisture content to no more than 5%, then crushed and passed through a 100-mesh sieve to remove large particles of impurities, resulting in tailings powder raw material with uniform particle size. Preparation of alkali activator: Select sodium silicate with a modulus of 2.0-3.0 and a mass fraction of 30%-40%, measure sodium silicate and water according to the ratio, mix and stir them evenly to prepare a uniform sodium silicate alkali activator solution; Mixing and stirring: Add the pretreated tailings powder to the mixing equipment, and then slowly add the prepared alkali activator solution. Control the stirring speed at 300-500 r / min and the stirring time at 5-10 min to ensure that the components are mixed evenly and form a fluid cementitious slurry. Backfilling construction: The well-mixed cementitious material slurry is directly transported to the mining goaf area and naturally cured for 3-7 days to solidify and harden into a backfill body with a certain strength, thus filling the mining goaf area.

[0015] Furthermore, the tailings powder from the metal mine is tailings produced by iron mines, copper mines, or lead-zinc mines, and its total mass fraction of active SiO2 and Al2O3 is not less than 50%, ensuring that sufficient hydration and gelation products can be generated during the alkali activation process.

[0016] Furthermore, the modulus and concentration of sodium silicate need to be strictly controlled. If the modulus is too low, the strength development of the cementitious material will be slow, and if the modulus is too high, it will affect the solubility and activation effect of the solution. A sodium silicate solution with a mass fraction of 30% to 40% can ensure activation efficiency and avoid poor slurry fluidity due to excessive concentration.

[0017] This invention also protects the alkali-activated tailings powder backfill cementitious material prepared by the above method. The cementitious material has an initial setting time of 4-6 hours, a final setting time of 8-12 hours, and a 28-day compressive strength of not less than 3.0 MPa, which meets the strength requirements for backfilling goaf areas in mines. At the same time, it has good stability and impermeability, and can effectively fill goaf areas and prevent surrounding rock collapse.

[0018] Furthermore, this invention also protects the application of this alkali-activated tailings powder backfill cementitious material in backfilling of mining goaf areas, which can realize the on-site resource utilization of tailings powder, eliminating the need for long-distance transportation and significantly reducing backfilling costs.

[0019] Beneficial effects This invention uses sodium silicate solution as an alkaline activator, which can efficiently activate the active SiO2 and Al2O3 in tailings powder of metal mines, causing them to undergo a hydration reaction to generate hydration products with cementing properties. The prepared cementitious material has the strength to meet the requirements of mine backfilling, with a 28-day compressive strength of not less than 3.0 MPa, and good stability and impermeability.

[0020] The mass ratio of each component is scientific and reasonable, with tailings powder: sodium silicate: water = 1170:154:315. This not only ensures the activation effect and the performance of the cementitious material, but also maximizes the utilization of tailings powder, realizes the resource utilization of waste, and reduces the environmental problems caused by tailings storage.

[0021] The preparation process is simple, requires no complex equipment, and uses widely available and inexpensive raw materials. It enables on-site mining, processing, and backfilling of tailings powder without the need for long-distance transportation, significantly reducing the production cost and energy consumption of mine backfilling, which aligns with the development concept of low-carbon and environmental protection.

[0022] This invention effectively solves the dual problems of tailings pollution and shortage of backfill materials in mining goaf areas, and has significant economic, environmental and social benefits with broad application prospects. The present invention and its embodiments have been described above, and such description is not restrictive. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preparing an alkali-activated tailings powder backfill cementitious material, characterized in that, Includes the following steps: Using metal mine tailings powder as the base material and sodium silicate solution as the alkali activator, the materials are mixed and stirred evenly, and then solidified and hardened to form a mine backfill cementitious material. The mass ratio of each component of the mine backfill cementitious material is tailings powder: sodium silicate: water = 1170:154:

315.

2. The method for preparing an alkali-activated tailings powder mine backfill cementitious material according to claim 1, characterized in that: The tailings powder from the metal mines refers to the tailings generated during the mining process of iron mines, copper mines, or lead-zinc mines, with a particle size range of 1-100 μm, and a total mass fraction of active SiO2 and Al2O3 ≥ 50%.

3. The method for preparing an alkali-activated tailings powder mine backfill cementitious material according to claim 1, characterized in that: The sodium silicate has a modulus of 2.0-3.0 and a mass fraction of 30%-40%.

4. A method for preparing an alkali-activated tailings powder mine backfill cementitious material according to any one of claims 1-3, characterized in that: This method yields alkali-activated tailings powder as a backfill cementitious material for mines.

5. The alkali-activated tailings powder backfill cementitious material according to claim 4 is applied to backfilling of mining goaf areas.