Mine backfill slurry and its rapid proportioning determination method

Abstract

The application discloses a mine backfilling slurry, a quick determination method of proportioning and a preparation method, and belongs to the technical field of solid waste resource utilization and mine filling. The slurry is composed of fluorgypsum slag, carbide slag, tailings and water. Firstly, the concentration of sulfate radical in the fluorgypsum slag filtrate and the concentration of calcium hydroxide in the carbide slag filtrate are respectively determined by chemical titration method, and the concentration ratio is calculated, and the concentration ratio is multiplied by the proportioning coefficient 26-30 to quickly determine the optimal mass proportioning of the fluorgypsum slag and the carbide slag; then the mixed slag and the tailings are mixed according to the mass ratio 1:2.5-3, and water is added to adjust the mass concentration of the slurry to 70%-75%, and the mine backfilling slurry is obtained. The application utilizes the cementing effect generated by the neutralization reaction of the fluorgypsum slag and the carbide slag, and does not need to add cement to meet the mine filling strength requirement, and realizes the collaborative resource utilization of the two kinds of industrial waste slag. The determination method of proportioning is quick and accurate, the slurry has great tolerance to fine tailings, does not separate, has small bleeding, and has short curing time.

Description

Technical Field

[0001] This invention relates to the fields of mine backfilling technology and resource utilization of industrial solid waste, specifically to a mine backfill slurry prepared using fluorogypsum slag and carbide slag and a rapid method for determining its proportion. Background Technology

[0002] Backfilling of mined-out areas is a crucial aspect of mine safety and environmental protection. Currently, domestic mine backfilling primarily employs methods such as dry backfilling, water-sand backfilling, cemented backfilling, paste backfilling, and backfilling with novel cementing materials. Among these, paste backfilling and cemented backfilling, using cement as the binding material, are the most widely used methods. However, these methods consume large amounts of cement and are costly, placing a heavy economic burden on mining enterprises.

[0003] On the other hand, chemical production processes generate large amounts of industrial waste, such as fluorogypsum slag and calcium carbide slag. Fluorogypsum slag mainly originates from the large amount of waste gypsum produced as a byproduct of fluorochemical production and is acidic; calcium carbide slag mainly comes from the hydrolysis reaction of calcium carbide during polyvinyl chloride (PVC) production and is strongly alkaline. Currently, these two types of waste are mostly disposed of through stockpiling, which occupies a large amount of land resources and poses environmental pollution risks.

[0004] There have been attempts to use industrial solid waste for mine backfilling in the existing technology, but most of them have the following shortcomings: (1) the utilization rate of solid waste is limited and additives such as cement are still required; (2) the adaptability to fine-grained tailings is poor and it is easy to segregate and stratify under high concentration conditions; (3) it is difficult to quickly and accurately control the pH value of the backfill slurry to a suitable range, which affects the strength development of the backfill body.

[0005] Especially when using fluorogypsum slag and carbide slag together, the ratio of fluorogypsum slag to carbide slag directly determines the pH value of the mixture, as fluorogypsum slag contains residual sulfuric acid and other acidic substances, while carbide slag contains calcium hydroxide and other alkaline substances. This ratio, in turn, affects the gelation reaction and the final strength of the filling material. Current technology lacks a method to quickly and accurately determine the ratio based on the properties of the raw materials, leading to long adjustment cycles and high costs in practical applications.

[0006] Therefore, developing a method for preparing mine backfill slurry that can fully utilize two types of solid waste, fluorogypsum slag and carbide slag, without adding cement, and can quickly and accurately determine the optimal ratio, is of great practical significance. Summary of the Invention

[0007] The purpose of this invention is to provide a rapid method for determining the proportion of mine backfill slurry.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] Option 1: Mine backfill slurry

[0010] A mine backfill slurry is composed of fluorogypsum slag, carbide slag, tailings, and water. The mass ratio of the fluorogypsum slag to the carbide slag is determined by the following method: the sulfate concentration in the fluorogypsum slag filtrate and the calcium hydroxide concentration in the carbide slag filtrate are measured separately, the concentration ratio is calculated, and the mass ratio of the concentration ratio is multiplied by a proportioning coefficient to obtain the mass ratio of the fluorogypsum slag to the carbide slag. The proportioning coefficient is 26-30. The mass ratio of the mixed fluorogypsum slag and carbide slag to the tailings is 1:2.5-3. The mass concentration of the slurry is 70%-75%.

[0011] Preferably, the slurry has a mass concentration of 75%.

[0012] Preferably, the mass ratio of the mixed fluorinated gypsum slag and carbide slag to tailings is 1:3.

[0013] Preferably, when the proportioning coefficient is 30, the pH value of the mixed residue is 6-7; when the proportioning coefficient is 28, the pH value of the mixed residue is 7-8; and when the proportioning coefficient is 26, the pH value of the mixed residue is 8-9.

[0014] Furthermore, the mass concentration of the mine backfill slurry is 75%, the mass ratio of mixed slag to tailings is 1:3, and the compressive strength meets the mine backfilling requirements after 10 days of curing.

[0015] Furthermore, the mass concentration of the mine backfill slurry is 70%, the mass ratio of mixed slag to tailings is 1:3, and the compressive strength meets the mine backfilling requirements after 14 days of curing.

[0016] Option 2: Rapid Determination Method for Mixture Ratio of Mine Backfill Slurry

[0017] A rapid method for determining the mix ratio of mine backfill slurry and slag includes the following steps:

[0018] S1. Weigh out 10g each of the fluorogypsum slag sample and the carbide slag sample;

[0019] S2. Dissolve the fluorogypsum slag sample and carbide slag sample weighed in step S1 in 100mL of distilled water respectively, and stir thoroughly for 3-5 minutes to ensure that the soluble acid and alkali are fully dissolved.

[0020] S3. Filter the fluorogypsum slag solution and the carbide slag solution using medium-speed filter paper, and collect the filtrates separately.

[0021] S4. Take the filtrate of fluoride gypsum residue and titrate it with 0.1 mol / L NaOH standard solution, and record the volume of NaOH solution consumed, V1.

[0022] S5. Take the carbide slag filtrate and titrate it with 0.1 mol / L HCl standard solution, and record the volume of HCl solution consumed, V2.

[0023] S6. Calculate the sulfate concentration in the fluoride gypsum residue filtrate using the following formula:

[0024] C(SO4) 2- )×V(SO4 2- ) = 2 × C(NaOH) × V1,

[0025] Among them, V(SO4) 2- ) represents the sampling volume of fluoride gypsum residue filtrate, C(NaOH) represents the concentration of NaOH standard solution, and V1 represents the volume of NaOH standard solution consumed;

[0026] S7. Calculate the concentration of calcium hydroxide in the calcium carbide slag filtrate using the following formula:

[0027] C(Ca(OH)2)×V(Ca(OH)2)=2×C(HCl)×V2,

[0028] Where V(Ca(OH)2) is the sampling volume of carbide slag filtrate, C(HCl) is the concentration of HCl standard solution, and V2 is the volume of HCl standard solution consumed;

[0029] S8. Calculate the concentration ratio R:

[0030] R=C(SO4 2- ) / C(Ca(OH)2),

[0031] S9. Based on the concentration ratio R multiplied by the proportioning coefficient K, the mass ratio of fluorogypsum slag to carbide slag is obtained:

[0032] Fluorogypsum slag : carbide slag = R × K,

[0033] The ratio coefficient K ranges from 26 to 30.

[0034] Preferably, when the proportioning coefficient K=30, the pH value of the mixed residue is 6-7; when the proportioning coefficient K=28, the pH value of the mixed residue is 7-8; and when the proportioning coefficient K=26, the pH value of the mixed residue is 8-9.

[0035] Option 3: Preparation method of mine backfill slurry

[0036] A method for preparing mine backfill slurry includes the following steps:

[0037] S11. Using the rapid determination method described in Scheme 2 above, determine the mass ratio of fluorogypsum slag and carbide slag.

[0038] S12. Weigh the fluorinated gypsum slag and carbide slag according to the mass ratio determined in step S11, mix them evenly to obtain a mixed slag, wherein the pH value of the mixed slag is 6 to 9.

[0039] S13. Mix the mixed slag obtained in step S12 with the tailings at a mass ratio of 1:2.5 to 3 to obtain a dry mixture;

[0040] S14. Add water to the dry mixture obtained in step S13 to make the mass concentration of the slurry reach 70% to 75%, and mix thoroughly to obtain the mine backfill slurry.

[0041] Preferably, the mass ratio of the mixed slag to the tailings in step S13 is 1:3.

[0042] Preferably, the mass concentration of the slurry in step S14 is 75%.

[0043] Furthermore, the proportioning coefficient mentioned in step S11 is selected according to the pH value of the mixed slag required by the actual process: when the required pH value of the mixed slag is 6 to 7, the proportioning coefficient K=30 is selected; when the required pH value of the mixed slag is 7 to 8, the proportioning coefficient K=28 is selected; when the required pH value of the mixed slag is 8 to 9, the proportioning coefficient K=26 is selected.

[0044] Furthermore, the tailings mentioned in step S3 are mineral processing tailings, and their moisture content, specific gravity and particle size distribution are measured before use.

[0045] Furthermore, the compressive strength of the mine backfill slurry, after being cured for 10 days at a mass concentration of 75%, meets the requirements for mine backfilling.

[0046] Furthermore, the compressive strength of the mine backfill slurry, after being cured for 14 days at a mass concentration of 70%, meets the requirements for mine backfilling.

[0047] The beneficial effects of this invention are as follows:

[0048] 1. This invention proposes for the first time a rapid method for determining the ratio of fluorogypsum slag and carbide slag based on the principle of chemical titration. By measuring the concentrations of acid and alkali in the two waste slags respectively, calculating the concentration ratio and multiplying it by the ratio coefficient, the optimal mass ratio of the two can be determined quickly and accurately, avoiding the disadvantages of traditional trial mixing methods that are time-consuming, labor-intensive, and have low accuracy.

[0049] 2. Through extensive experimental research, this invention has determined the range of the proportioning coefficient K = 26 to 30 and clarified the pH range of the mixed slag corresponding to different proportioning coefficients. The proportioning coefficient can be flexibly selected according to actual process needs, thus achieving precise control of the pH value of the mixed slag.

[0050] 3. This invention utilizes the residual sulfuric acid in fluorogypsum slag to neutralize the calcium hydroxide in carbide slag. The reaction product has certain cementitious activity, and can form the strength required for mine backfilling without adding any cement, which greatly reduces the cost of backfilling materials.

[0051] 4. This invention has a high tolerance for the fine particles of tailings. The slurry does not segregate or separate under the condition of a mass concentration of 70% to 75%, has little bleeding, and a short curing time. Moreover, under the same strength conditions, the amount of cementitious material used in this invention is less than that of cement.

[0052] 5. This invention realizes the synergistic resource utilization of two industrial waste residues, fluorogypsum slag and carbide slag, turning waste into treasure. It not only solves the environmental problems and disposal costs caused by solid waste stockpiling, but also significantly reduces the material cost of mine backfilling, and has good economic and environmental benefits.

[0053] 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

[0054] 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.

[0055] Example 1

[0056] This embodiment provides a mine backfill slurry and its preparation method.

[0057] I. Proportioning Determination

[0058] 10g of fluoride gypsum residue, a byproduct of a chemical plant, was dissolved in 100mL of distilled water and stirred thoroughly for 3 minutes. The solution was then filtered through medium-speed filter paper. The filtrate was titrated with 0.1mol / L NaOH standard solution, consuming a volume of NaOH solution, V1 = 15.2mL. Separately, 10g of calcium carbide slag, also a byproduct of the same plant, was dissolved in 100mL of distilled water and stirred thoroughly for 3 minutes. The solution was then filtered through medium-speed filter paper. The filtrate was titrated with 0.1mol / L HCl standard solution, consuming a volume of HCl solution, V2 = 12.8mL.

[0059] Calculate the sulfate concentration in the filtrate of fluorogypsum residue:

[0060] C(SO4 2- )=2×0.1×15.2 / 100=0.0304 mol / L,

[0061] Calculate the calcium hydroxide concentration in the carbide slag filtrate:

[0062] C(Ca(OH)2)=2×0.1×12.8 / 100=0.0256 mol / L,

[0063] The concentration ratio R = 0.0304 / 0.0256 = 1.1875.

[0064] If the ratio coefficient K=30 is selected, and the pH value of the mixed slag is 6-7, then the mass ratio of fluorogypsum slag to carbide slag is 1.1875×30=35.625:1.

[0065] II. Slurry Preparation

[0066] Weigh out fluoride gypsum slag and carbide slag according to the above ratio, and mix them evenly to obtain mixed slag. Mix the mixed slag with tailings at a mass ratio of 1:3, add an appropriate amount of water to adjust the slurry mass concentration to 75%, and stir thoroughly to obtain the mine backfill slurry.

[0067] III. Performance Testing

[0068] The obtained slurry was made into standard specimens for curing and testing. The results showed that the slurry did not segregate or separate into layers, and had minimal bleeding; after 10 days of curing, the compressive strength reached 2.8 MPa, meeting the requirements for mine backfilling.

[0069] Example 2

[0070] This embodiment provides a mine backfill slurry and its preparation method.

[0071] The sources of fluorogypsum slag and carbide slag are the same as in Example 1. Following the determination method of Example 1, the concentration ratio R = 1.1875. Using a proportioning coefficient K = 28, corresponding to a mixed slag pH of 7–8, the mass ratio of fluorogypsum slag to carbide slag is 1.1875 × 28 = 33.25:1.

[0072] Prepare the mixed slag according to the above ratio, mix the mixed slag and tailings at a mass ratio of 1:3, add water to adjust the slurry mass concentration to 70%, and stir thoroughly to obtain the mine backfill slurry.

[0073] The obtained slurry was made into standard specimens for curing and testing. The results showed that the compressive strength reached 2.5 MPa after 14 days of curing, which meets the requirements for mine backfilling.

[0074] Example 3

[0075] This embodiment provides a mine backfill slurry and its preparation method.

[0076] The sources of fluorogypsum slag and carbide slag are the same as in Example 1. Following the determination method of Example 1, the concentration ratio R = 1.1875. Using a proportioning coefficient K = 26, corresponding to a mixed slag pH of 8–9, the mass ratio of fluorogypsum slag to carbide slag = 1.1875 × 26 = 30.875:1.

[0077] Prepare the mixed slag according to the above ratio, mix the mixed slag and tailings at a mass ratio of 1:2.5, add water to adjust the slurry mass concentration to 75%, and stir thoroughly to obtain the mine backfill slurry.

[0078] The obtained slurry was made into standard specimens for curing and testing. The results showed that the compressive strength reached 2.2 MPa after 10 days of curing, which meets the requirements for mine backfilling.

[0079] Comparative Example 1

[0080] The ratio of fluorogypsum slag to carbide slag was determined by trial mixing, which involved continuously adjusting the ratio and testing the pH value, with a target pH value of 7. The results showed that five repeated trials were needed to determine the approximate ratio range, and each trial required drying, weighing, dissolving, filtering, and testing, taking a total of over 8 hours, which is far less efficient than the method of this invention.

[0081] Comparative Example 2

[0082] The ratio of mixed slag to tailings was adjusted to 1:4, with other conditions remaining the same as in Example 1. The results showed that the proportion of cementitious material in the slurry was insufficient, and the compressive strength after 14 days of curing was only 1.2 MPa, failing to meet the mine backfilling requirements.

[0083] Comparative Example 3

[0084] The slurry concentration was adjusted to 65%, and other conditions were the same as in Example 1. The results showed that the slurry exhibited obvious bleeding and segregation, and the compressive strength was only 1.0 MPa after 14 days of curing.

[0085] Comparative Example 4

[0086] The slurry concentration was adjusted to 80%, with other conditions remaining the same as in Example 1. The results showed that the slurry had poor fluidity and could not meet the requirements for pipeline pumping.

[0087] Industrial applicability

[0088] The present invention relates to a rapid method for determining the proportion of mine backfill slurry and its mix design. This method utilizes two solid wastes—fluorogypsum slag and carbide slag—generated by chemical enterprises to prepare mine backfill materials. The mix design is rapid and accurate, the slurry preparation process is simple, it has high tolerance for fine-grained tailings, and it meets strength requirements without the need for cement. This method is applicable to various types of mine goaf backfilling projects and has promising prospects for industrial application.

[0089] 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.

[0090] 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.

[0091] 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 fluorogypsum slag, carbide slag, tailings, and water. The mass ratio of the fluorogypsum slag to the carbide slag is determined by the following method: the concentration of sulfate in the fluorogypsum slag filtrate and the concentration of calcium hydroxide in the carbide slag filtrate are measured respectively, the concentration ratio is calculated, and the mass ratio is obtained by multiplying the concentration ratio by the proportioning coefficient. The proportioning coefficient is 26-30. The mass ratio of the mixed fluorogypsum slag and carbide slag to the tailings is 1:2.5-3. The mass concentration of the slurry is 70%-75%.

2. The mine backfill slurry according to claim 1, characterized in that, The slurry has a mass concentration of 75%, and the mass ratio of the mixed slag to the tailings is 1:

3.

3. The mine backfill slurry according to claim 1, characterized in that, When the ratio coefficient is 30, the pH value of the mixed residue is 6-7; when the ratio coefficient is 28, the pH value of the mixed residue is 7-8; when the ratio coefficient is 26, the pH value of the mixed residue is 8-9.

4. A rapid method for determining the mix ratio of mine backfill slurry and slag, characterized in that, Includes the following steps: S1. Weigh 10g of each of the fluorogypsum residue sample and the carbide residue sample, dissolve them in 100mL of distilled water, and stir for 3-5 minutes. S2. Filter and collect the filtrate separately; S3. Take the filtrate of fluorogypsum residue and titrate it with 0.1 mol / L NaOH standard solution, and record the volume consumed V1; take the filtrate of carbide residue and titrate it with 0.1 mol / L HCl standard solution, and record the volume consumed V2. S4, According to formula C(SO4) 2- )×V(SO4 2- The sulfate concentration is calculated as C(Ca(OH)2)×V1. The calcium hydroxide concentration is calculated using the formula C(Ca(OH)2)×V(Ca(OH)2)=2×C(HCl)×V2. Then, the concentration ratio R=C(SO4)2 is calculated. 2- ) / C(Ca(OH)2); S5. Multiply the concentration ratio R by the proportioning coefficient K, where K is 26-30, to obtain the mass ratio of fluorogypsum slag and carbide slag.

5. The rapid determination method according to claim 4, characterized in that, When K=30, the pH value of the mixed residue is 6-7; when K=28, the pH value is 7-8; and when K=26, the pH value is 8-9.

6. A method for preparing mine backfill slurry, characterized in that, Includes the following steps: S11. Determine the mass ratio of fluorogypsum slag and carbide slag so that the pH value of the mixed slag obtained after mixing the two is 6 to 9. S12. Weigh out fluorinated gypsum slag and carbide slag according to the ratio, mix them evenly to obtain mixed slag; S13. Mix the mixed slag and tailings at a mass ratio of 1:2.5 to 3 to obtain a dry mixture; S14. Add water to the dry mixture to make the slurry concentration reach 70% to 75%, and stir thoroughly to obtain the mine backfill slurry.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the mixed slag to the tailings in step S13 is 1:3, and the mass concentration of the slurry in step S14 is 75%.

8. The preparation method according to claim 6, characterized in that, In step S11, the proportioning coefficient K is selected according to the required pH value of the mixed residue to determine the mass proportion: when the required pH value is 6 to 7, K=30 is selected; when the required pH value is 7 to 8, K=28 is selected; and when the required pH value is 8 to 9, K=26 is selected.