Mine backfill slurry and method of making same

Abstract

The application discloses a kind of mine backfilling slurry and preparation method thereof, belong to solid waste resource utilization technical field.The slurry is composed of gypsum residue, carbide slag, sand and water, wherein the mass ratio of gypsum residue and carbide slag is 26-30:1, the mass ratio of mixed slag and sand is 1:2-3.5, and the water addition amount is 25%-50% of the total mass of mixed slag and sand.The preparation method includes: drying and sieving gypsum residue and carbide slag respectively, mixing the mixed slag in proportion to obtain mixed slag, then mixing the mixed slag with sand in proportion to obtain dry mixture, and finally adding water and stirring to obtain the slurry.The application utilizes the synergistic gel effect of gypsum residue and carbide slag, and can prepare a slurry that meets the strength requirements of mine backfilling without adding cement, realizes efficient resource utilization of two kinds of industrial solid waste, and has the advantages of simple process, low cost, significant environmental benefits, etc.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, specifically to a mine backfill slurry prepared using gypsum slag and carbide slag and its preparation method. Background Technology

[0002] Mine backfilling is an important process for filling goaf areas during mining operations. Traditional backfilling materials mostly use cement as a binder, which is costly. With the acceleration of industrialization, the amount of various industrial solid wastes generated is increasing year by year, and how to achieve the resource utilization of solid waste has become an urgent technical problem to be solved.

[0003] Gypsum slag and calcium carbide slag are major solid wastes generated during chemical production. Gypsum slag mainly originates from wet-process phosphoric acid production and flue gas desulfurization processes, while calcium carbide slag primarily comes from the calcium carbide hydrolysis reaction during polyvinyl chloride (PVC) production. Currently, large quantities of gypsum slag and calcium carbide slag are disposed of through stockpiling, which not only occupies significant land resources but also poses environmental pollution risks.

[0004] Existing technologies have attempted to use industrial solid waste for mine backfilling, but these often involve single types of solid waste or require the addition of large amounts of cement and other additives, resulting in limited solid waste utilization. For example, some solutions use fly ash mixed with cement as backfill material, but the cement consumption remains high, leading to insufficient economic benefits. Other studies have attempted to utilize the alkaline activation properties of carbide slag to prepare backfill materials, but these often suffer from insufficient strength and high bleeding rates.

[0005] Therefore, developing a slurry preparation method that can fully utilize the synergistic effect of gypsum slag and carbide slag, and meet the backfill strength requirements of mines without adding cement, has significant economic value and environmental significance. Summary of the Invention

[0006] The purpose of this invention is to provide a mine backfill slurry and a method for preparing the same.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A mine backfill slurry is composed of gypsum slag, carbide slag, sand and gravel and water; the mass ratio of gypsum slag to carbide slag is 26-30:1; the mass ratio of the mixed gypsum slag and carbide slag to sand and gravel is 1:2-3.5; and the amount of water added is 25%-50% of the total mass of the mixed slag and sand and gravel.

[0009] Preferably, the mass ratio of gypsum slag to carbide slag is 30:1.

[0010] Preferably, the mass ratio of the mixed slag to sand and gravel is 1:3.

[0011] Preferably, the amount of water added is 35% of the total mass of the mixed slag and sand.

[0012] Furthermore, the pH value of the mixture of gypsum slag and carbide slag is 6 to 9.

[0013] Preferably, when the pH value of the mixed slag is 6 to 9, the mass ratio of the gypsum slag to the carbide slag is 26 to 30:1.

[0014] A method for preparing mine backfill slurry includes the following steps:

[0015] S1. Dry the gypsum slag and carbide slag at 105℃ for 8 hours, and then sieve them through a 5mm sieve to obtain dried gypsum slag powder and carbide slag powder.

[0016] S2. Mix the gypsum slag powder and carbide slag powder obtained in step S1 at a mass ratio of 26-30:1 to obtain a mixed slag.

[0017] S3. Mix the mixed slag obtained in step S2 with sand and gravel at a mass ratio of 1:2 to 3.5 to obtain a dry mixture;

[0018] S4. Add water to the dry mixture obtained in step S3. The amount of water added is 25% to 50% of the total mass of the dry mixture. Stir and mix thoroughly to obtain the mine backfill slurry.

[0019] Preferably, the mass ratio of gypsum slag to carbide slag in step S2 is 30:1.

[0020] Preferably, the mass ratio of the mixed slag to the sand and gravel in step S3 is 1:3.

[0021] Preferably, the amount of water added in step S4 is 35% of the total mass of the dry mixture.

[0022] Furthermore, the slump of the mine backfill slurry is 180–250 mm.

[0023] Furthermore, the compressive strength of the mine backfill slurry after 10 days of curing is not less than 2.0 MPa, and the compressive strength after 14 days of curing is not less than 2.5 MPa.

[0024] Furthermore, the flexural strength of the mine backfill slurry after 10 days of curing is not less than 0.5 MPa, and the flexural strength after 14 days of curing is not less than 0.6 MPa.

[0025] Furthermore, the chloride and fluoride ion contents in the leachate of the mine backfill slurry both meet the environmental protection requirements for mine backfilling.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention is the first to blend gypsum slag and carbide slag in a specific ratio, utilizing the synergistic activating effect of the sulfate components in the gypsum slag and the alkaline components in the carbide slag to form a cementitious system without adding any cement, thus achieving the efficient synergistic utilization of the two solid wastes. Extensive experiments determined the optimal mixing ratio of gypsum slag and carbide slag. Within this ratio, the pH value of the mixed slag is within a suitable range of 6-9, ensuring the smooth progress of the cementation reaction while avoiding alkaline pollution to the underground environment.

[0028] This invention, through a systematic study of the relationship between material proportions, water proportions, slump, compressive strength, and flexural strength, determined the optimal proportioning scheme. The resulting backfill slurry exhibits good fluidity and sufficient early strength, fully meeting the engineering requirements for mine backfilling. The method of this invention is simple, easy to operate, requires no complex equipment, and can be directly applied using existing mine backfilling systems, resulting in low industrialization costs.

[0029] This invention realizes the synergistic resource utilization of two solid wastes, gypsum slag and carbide slag, turning waste into treasure. It not only solves the environmental problems caused by solid waste stockpiling, but also significantly reduces the material cost of mine backfilling, and has good economic and environmental benefits.

[0030] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1

[0033] This embodiment provides a mine backfill slurry and its preparation method.

[0034] Raw material preparation: Take gypsum slag and carbide slag, dry them at 105℃ for 8 hours, and sieve them through a 5mm sieve for later use.

[0035] Proportioning: Weigh the dried gypsum slag powder and carbide slag powder according to a mass ratio of 30:1 and mix them evenly to obtain a mixed slag; mix the mixed slag with sand and gravel at a mass ratio of 1:3 to obtain a dry mixture; add water to the dry mixture, the amount of water added being 35% of the total mass of the dry mixture.

[0036] Preparation: Place the above raw materials in a planetary cement mortar mixer and mix thoroughly to obtain mine backfill slurry.

[0037] Performance Testing: The performance of the slurry was tested according to relevant standards. Slump test results showed that the slump of the slurry was 200–230 mm, exhibiting good fluidity and pumpability. Standard specimens of the slurry were prepared and cured under standard conditions for 10 and 14 days. Compressive strength and flexural strength were tested, and the chloride and fluoride ion content in the exudate was also measured.

[0038] The results showed that after 10 days of curing, the compressive strength reached 2.2 MPa and the flexural strength reached 0.55 MPa; after 14 days of curing, the compressive strength reached 2.8 MPa and the flexural strength reached 0.65 MPa. The chloride and fluoride ion contents in the leachate both met the environmental protection standards for mine backfilling.

[0039] Example 2

[0040] This embodiment provides a mine backfill slurry and its preparation method.

[0041] The raw material preparation is the same as in Example 1.

[0042] Proportioning: Weigh the dried gypsum slag powder and carbide slag powder according to the mass ratio of gypsum slag to carbide slag of 28:1, mix them evenly to obtain a mixed slag with a pH value of 7-8; mix the mixed slag with sand and gravel at a mass ratio of 1:2.5 to obtain a dry mixture; add water to the dry mixture, the amount of water added is 35% of the total mass of the dry mixture.

[0043] The preparation method is the same as in Example 1.

[0044] Performance testing: The slump of the obtained slurry was 190–220 mm. After 10 days of curing, the compressive strength reached 2.0 MPa and the flexural strength reached 0.50 MPa; after 14 days of curing, the compressive strength reached 2.5 MPa and the flexural strength reached 0.60 MPa.

[0045] Example 3

[0046] This embodiment provides a mine backfill slurry and its preparation method.

[0047] The raw material preparation is the same as in Example 1.

[0048] Proportioning: Weigh the dried gypsum slag powder and carbide slag powder according to the mass ratio of gypsum slag to carbide slag of 26:1, mix them evenly to obtain a mixed slag with a pH value of 8-9; mix the mixed slag with sand and gravel at a mass ratio of 1:2 to obtain a dry mixture; add water to the dry mixture, the amount of water added is 35% of the total mass of the dry mixture.

[0049] The preparation method is the same as in Example 1.

[0050] Performance testing: The slump of the obtained slurry was 180–210 mm. After 10 days of curing, the compressive strength reached 1.8 MPa and the flexural strength reached 0.45 MPa; after 14 days of curing, the compressive strength reached 2.2 MPa and the flexural strength reached 0.55 MPa.

[0051] Comparative Example 1

[0052] Backfill slurry was prepared with a gypsum slag to carbide slag mass ratio of 35:1 and a pH value <6, while other conditions were the same as in Example 1. The results showed that the slurry's setting performance was significantly worse, and the compressive strength after 14 days of curing was only 1.2 MPa, which did not meet the requirements for mine backfilling.

[0053] Comparative Example 2

[0054] Backfill slurry was prepared with a gypsum slag to carbide slag mass ratio of 22:1 and a pH value > 9, while other conditions were the same as in Example 1. The results showed that the slurry was too alkaline, the pH value of the leachate exceeded the standard, and the compressive strength after 14 days of curing was only 1.5 MPa.

[0055] Comparative Example 3

[0056] The water ratio was 45%, and other conditions were the same as in Example 1. The results showed that the slump of the slurry increased to over 260 mm, but the compressive strength dropped to 1.8 MPa after 14 days of curing, which was insufficient.

[0057] Comparative Example 4

[0058] The water ratio was 25%, and other conditions were the same as in Example 1. The results showed that the slump of the slurry was only 120 mm, indicating poor fluidity, which could not meet the requirements for pumping construction.

[0059] Industrial applicability

[0060] The method for preparing mine backfill slurry of the present invention is simple in process, uses widely available raw materials, and is low in cost. It can utilize two solid wastes, gypsum slag and carbide slag, generated by chemical enterprises to prepare mine backfill materials, thus solving the problem of solid waste disposal and reducing the cost of mine backfilling. This method is applicable to backfilling projects in various types of mine goaf areas and has good prospects for industrial promotion and application.

[0061] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A mine backfill slurry, characterized in that, It is composed of gypsum slag, carbide slag, sand and gravel and water; the mass ratio of gypsum slag to carbide slag is 26 to 30:1; the mass ratio of the mixed gypsum slag and carbide slag to sand and gravel is 1:2 to 3.5; the amount of water added is 25% to 50% of the total mass of the mixed slag and sand and gravel.

2. The mine backfill slurry according to claim 1, characterized in that, The mass ratio of gypsum slag to carbide slag is 30:

1.

3. The mine backfill slurry according to claim 1, characterized in that, The mass ratio of the mixed slag to sand and gravel is 1:

3.

4. The mine backfill slurry according to claim 1, characterized in that, The amount of water added is 35% of the total mass of the mixed slag and sand.

5. The mine backfill slurry according to any one of claims 1 to 4, characterized in that, The pH value of the mixture of gypsum slag and carbide slag is 6 to 9.

6. A method for preparing mine backfill slurry as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Dry the gypsum slag and carbide slag at 105℃ for 8 hours, and then sieve them through a 5mm sieve to obtain dried gypsum slag powder and carbide slag powder. S2. Mix the gypsum slag powder and carbide slag powder obtained in step S1 at a mass ratio of 26-30:1 to obtain a mixed slag. S3. Mix the mixed slag obtained in step S2 with sand and gravel at a mass ratio of 1:2 to 3.5 to obtain a dry mixture; S4. Add water to the dry mixture obtained in step S3. The amount of water added is 25% to 50% of the total mass of the dry mixture. Stir and mix thoroughly to obtain the mine backfill slurry.

7. The preparation method according to claim 6, characterized in that, The mass ratio of gypsum slag to carbide slag in step S2 is 30:

1.

8. The preparation method according to claim 6, characterized in that, The mass ratio of the mixed slag to the sand and gravel in step S3 is 1:

3.

9. The preparation method according to claim 6, characterized in that, The amount of water added in step S4 is 35% of the total mass of the dry mixture.

10. The preparation method according to claim 6, characterized in that, The compressive strength of the mine backfill slurry after 10 days of curing shall not be less than 2.0 MPa, and the compressive strength after 14 days of curing shall not be less than 2.5 MPa.