A red mud waste rock cooperative filling method and filling process system

Abstract

The embodiment of the application discloses a red mud waste rock cooperative filling method and a filling process system, and relates to the technical field of mine filling. The red mud waste rock cooperative filling method is designed to improve the quality and stability of filling slurry, and comprises the following steps: mixing and diluting filter cake with dilution water to obtain red mud slurry with a mass concentration of 20-40% and sending the red mud slurry into a thickener; in the thickener, an anionic polyacrylamide flocculating agent is added, and flocculation and sedimentation treatment is performed in the thickener; after thickening and sedimentation, the overflow water in the upper part of the thickener is collected, and the bottom part of the thickener obtains red mud underflow with a mass concentration of 55-70%; waste rock aggregates are obtained by treating waste rock, and the waste rock aggregates form continuous complementary gradation with the red mud underflow particles; the red mud underflow, the waste rock aggregates and cementing materials are sent into a mixer according to specified proportions; the mixer is started, and the filling slurry is obtained after stirring for a predetermined time, and the filling slurry is used for filling. The embodiment of the application is suitable for the mine filling scene.

Description

Technical Field

[0001] This application relates to the field of mine backfilling technology, and in particular to a method and process system for co-filling red mud and waste rock. Background Technology

[0002] Red mud is a highly alkaline solid waste discharged during alumina production, and its red color is due to its high iron oxide content. Statistics show that the global annual discharge of red mud exceeds 150 million tons. As a major alumina producer, my country has accumulated billions of tons of red mud, but its comprehensive utilization rate is less than 10%. Open-air storage of red mud not only occupies large amounts of land and increases the construction and maintenance costs of storage sites for enterprises, but its high alkalinity also easily leads to soil alkalization and groundwater pollution. Furthermore, the dust generated after drying causes air pollution, placing enormous pressure on the ecological environment.

[0003] In existing technologies, red mud is pressed and filtered into filter cakes, which are then used as backfill material. However, due to the caking and clumping of the filter cakes, they cannot be measured or transported, and therefore cannot be used directly for backfilling. Furthermore, when the filter cakes are processed into backfill slurry and stirred separately, the slurry has high viscosity, is prone to clumping, and has poor mixing uniformity. Backfill slurry prepared by existing technologies also suffers from difficulties in maintaining the critical settling concentration, and the coarse aggregate and fine mud are prone to segregation in the pipe, resulting in insufficient quality of the backfill body formed by the backfill slurry and large fluctuations in the quality of the backfill slurry. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a method and process system for co-filling red mud and waste rock, which facilitates the improvement of the quality and stability of the filling slurry.

[0005] In a first aspect, embodiments of this application provide a method for co-filling red mud and waste rock, comprising: mixing and diluting filter cake with dilution water to obtain red mud slurry with a mass concentration of 20-40%, and sending it into a thickener through a transfer pump A; Anionic polyacrylamide flocculant is added to the thickener for flocculation and sedimentation; wherein the amount of anionic polyacrylamide flocculant added is 30~40g / t red mud slurry. After thickening and settling, the upper overflow water in the thickener flows into the overflow water collection tank, and the bottom of the thickener obtains red mud bottom flow with a mass concentration of 55-70%. The waste rock is crushed and screened to obtain waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. 80-120 parts of red mud bottom flow with a mass concentration of 55-70% are fed into the mixer through a pipeline, and 25-50 parts of waste stone aggregate are fed into the mixer at the same time. 4-10 parts of the cementitious material are fed into the mixer via a conveyor. Start the mixer and mix for a predetermined time to obtain a filling slurry; The filling slurry is transported to the goaf area via pipeline using a filling pump for filling.

[0006] Optionally, the step of feeding 80-120 parts of the red mud bottom flow with a mass concentration of 55-70% into the mixer through a pipeline includes: feeding 100 parts of the red mud bottom flow with a mass concentration of 65% into the mixer through a pipeline.

[0007] Optionally, the step of simultaneously feeding 25-50 parts of waste stone aggregate into the mixer includes: simultaneously feeding 40 parts of waste stone aggregate into the mixer.

[0008] Optionally, the particle size of the waste stone aggregate is ≤15mm.

[0009] Optionally, feeding 4-10 parts of the gelling material into the mixer via a conveyor includes feeding 6 parts of the gelling material into the mixer via the conveyor.

[0010] Optionally, before starting the mixer, the red mud and waste rock co-filling method further includes feeding 5-20 parts of the overflow water from the top into the mixer via a delivery pump B to adjust the slurry concentration.

[0011] Optionally, in the filling slurry, 65-80% of the red mud particles have a particle size of less than 75μm, and the waste stone aggregate has a particle size of 0.15-15mm.

[0012] Secondly, embodiments of this application provide a red mud-waste rock co-filling process system for implementing the red mud-waste rock co-filling method described in any one of the first aspects, including: A red mud thickening and settling unit includes a red mud slurry storage tank, a conveying pump A, and a thickener; the red mud slurry storage tank is provided with a dilution water addition port; the outlet A of the red mud slurry storage tank is connected to the inlet A of the thickener through the conveying pump A; Waste rock aggregate preparation unit, used to process waste rock into waste rock aggregate; A filling slurry preparation unit is used to mix and stir the input overflow water, cementing material, red mud bottom flow and waste rock aggregate to prepare filling slurry; The overflow water collection and reuse unit includes an overflow water collection tank and a transfer pump B; the inlet of the overflow water collection tank is connected to the upper overflow port of the thickener, and the outlet B of the overflow water collection tank inputs the overflow water into the filling slurry preparation unit through the transfer pump B; the outlet of the overflow water collection tank is also connected to the dilution water addition port. The filling and conveying unit is connected to the filling slurry preparation unit and is used to convey the filling slurry to the area to be filled.

[0013] Optionally, the filling slurry preparation unit is provided with an inlet for the preparation water of overflow water, red mud bottom flow, waste rock aggregate and cementitious material, a red mud inlet, an aggregate inlet and a cementitious material inlet respectively; each inlet and water inlet of the filling slurry preparation unit is equipped with a metering and regulating component; the water inlet timing is matched with the cementitious material inlet timing; the red mud inlet and aggregate inlet timing are matched.

[0014] Optionally, the red mud slurry storage tank is equipped with a stirring device A, and the filling slurry preparation unit includes a mixer B. The stirring device A is an adjustable frequency stirring device with a rotation speed of 0~25 rpm; the mixer B is a fixed frequency mixer with a rotation speed of 40~60 rpm.

[0015] The red mud and waste rock co-filling method and filling process system provided in this application have the following beneficial effects: 1. Diluting the filter cake to obtain a red mud slurry with a mass concentration of 20-40% is beneficial to breaking up the filter cake clumping and improving the uniformity of mixing, thereby facilitating the improvement of the quality of the filling slurry; 2. Adding anionic polyacrylamide flocculant to the thickener binds suspended coarse and fine particles in the red mud into flocs for co-settling, which helps to increase the settling velocity. The flocs also encapsulate the coarse and fine particles together for co-settling, reducing particle size classification and improving settling stability / aggregation stability, which is conducive to forming a homogeneous and stable red mud bottom flow. Combined with the settling treatment of the mixture, a red mud bottom flow with a mass concentration of 55-70% is obtained, and the waste stone aggregate and red mud bottom flow particles form a continuous complementary gradation. The multi-stage uniform mixing treatment facilitates the improvement of the quality stability of the filling slurry. 3. The proportions of each component in the filling slurry are matched according to the specified range to improve the fluidity of the filling slurry and the quality of the final filling body strength. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the red mud and waste rock co-filling method according to an embodiment of this application; Figure 2 This is a schematic diagram of a red mud and waste rock co-filling process system according to an embodiment of this application; Figure 3 This is a schematic diagram of the red mud and waste rock co-filling method according to another embodiment of this application; In the diagram: 1. Red mud thickening and settling unit; 11. Red mud slurry storage tank; 111. Dilution water inlet; 112. Outlet A; 12. Conveying pump A; 13. Thickener; 131. Feed inlet A; 132. Bottom flow outlet; 133. Overflow outlet; 14. Flow meter A; 15. Concentrator; 16. Red mud bottom flow pump; 17. Feed pipeline; 171. Flocculant inlet; 172. Blending water inlet; 2. Waste rock aggregate preparation unit; 21. Waste rock silo; 22. Crusher; 23. Screening machine; 24. Waste rock aggregate silo; 25. Metering and feeding control assembly; 3. Filling slurry. Preparation Unit; 31. Mixer B; 32. Red Mud Inlet; 33. Aggregate Inlet; 34. Cementitious Material Inlet; 35. Preparation Water Inlet; 36. Discharge Outlet A; 4. Overflow Water Collection and Reuse Unit; 41. Overflow Water Collection Tank; 411. Inlet C; 412. Outlet B; 413. Outlet C; 42. Conveying Pump B; 43. Flow Metering and Adjustment Component; 431. Flow Meter B; 432. Adjusting Valve B; 5. Filling and Conveying Unit; 51. Filling Pump; 6. Cementitious Material Storage and Metering Unit; 61. Cementitious Material Storage Silo; 62. Feeder; 63. Conveyor. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0020] Example 1 See Figure 1 This application provides a method for co-filling red mud and waste rock, comprising: The filter cake is mixed and diluted with dilution water to obtain a red mud slurry with a mass concentration of 20-40%, which is then sent to a thickener via a transfer pump A. Anionic polyacrylamide flocculant is added to the thickener for flocculation and sedimentation; wherein the amount of anionic polyacrylamide flocculant added is 30~40g / t red mud slurry. After thickening and settling, the upper overflow water in the thickener flows into the overflow water collection tank, and the bottom of the thickener obtains red mud bottom flow with a mass concentration of 55-70%. The waste rock is crushed and screened to obtain waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. 80-120 parts of red mud bottom flow with a mass concentration of 55-70% are fed into the mixer through a pipeline, and 25-50 parts of waste stone aggregate are fed into the mixer at the same time. 4-10 parts of the cementitious material are fed into the mixer via a conveyor. Start the mixer and mix for a predetermined time to obtain a filling slurry; The filling slurry is transported to the goaf area via pipeline using a filling pump for filling.

[0021] In this embodiment, the filter cake is first diluted to obtain a red mud slurry with a mass concentration of 20-40%. This facilitates the dispersal of filter cake agglomeration, improves the uniformity of stirring, thereby improving the viscosity of the filling slurry, preventing agglomeration, and improving the quality of the filling slurry. The red mud slurry with a mass concentration of 20-40% is then fed into the thickener via a transfer pump A. The concentration of the red mud slurry is controlled at 20-40%, which ensures fluidity for easy pumping and avoids excessive load on subsequent thickening processes due to excessively thin red mud slurry.

[0022] Unflocculated red mud exhibits rapid settling of coarse particles and slow settling of fine particles, easily leading to stratification of coarse and fine particles in the underflow, resulting in uneven underflow properties. Adding anionic polyacrylamide flocculant to the thickener utilizes the adsorption and bridging effect of its long molecular chains to link suspended coarse and fine particles in the red mud into large, dense flocs. These flocs settle much faster than ordinary inorganic flocculants, significantly shortening the solid-liquid separation cycle of the slurry. Simultaneously, the flocs encapsulate coarse and fine particles, causing them to settle together, reducing particle size distribution and improving settling and aggregation stability. This promotes the formation of a homogeneous and stable red mud underflow, resulting in a more uniform overall concentration of the filling slurry. The more uniform the concentration of the filling slurry, the better the quality of the final filling body formed. When adding anionic polyacrylamide flocculant to the thickener, 30-40g of flocculant should be added per ton of red mud slurry.

[0023] The process involves flocculating and settling red mud slurry in a thickener to accelerate particle aggregation and settling, forming a uniform and dense red mud bottom flow. This improves the efficiency of thickening and settling of red mud slurry in the thickener, while also facilitating the production of clear overflow water, reducing the solids content in the overflow water, and fully utilizing the resources of the substances in the overflow water. The upper overflow water from the thickening and settling process is then transported to an overflow water collection tank and used entirely for preparing filling slurry. Furthermore, a red mud bottom flow with a mass concentration of 55-70% is obtained at the bottom of the thickener.

[0024] Waste rock generated from mining is crushed and screened to obtain waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. When preparing filling slurry, the particle size distribution of waste rock aggregate and red mud fine particles is nested to achieve maximum bulk density and reduce porosity. The slurry viscosity is significantly reduced while maintaining fluidity. The waste rock aggregate and red mud bottom flow particles form a continuous complementary gradation. Multi-stage uniform mixing treatment facilitates the improvement of filling slurry quality stability.

[0025] 80-120 parts of red mud bottom flow with a mass concentration of 55-70% and 25-50 parts of waste rock aggregate are simultaneously fed into the mixer. During the mixing process, the shearing action of the waste rock breaks up the particle agglomeration structure in the red mud bottom flow. This solves the technical problem of easy agglomeration and poor uniformity when red mud bottom flow is mixed alone, improves the viscosity of the filling slurry, enhances the mixing uniformity, improves the quality of the filling slurry, shortens the mixing time, and improves the efficiency of filling construction.

[0026] In addition, 4 to 10 parts of cementitious material are fed into the mixer. During the mixing process, the shearing action of the waste rock is used to break up the agglomeration of the cementitious material, preventing the cementitious material from forming lumps that are wet on the outside and dry on the inside in the mixer, thereby improving the uniformity of mixing and enhancing the quality of the filling slurry.

[0027] After starting the mixer, the specified mass concentration and proportion of red mud bottom flow, waste rock aggregate, and cementitious material are stirred in the mixer for a predetermined time to obtain a filling slurry with uniform viscosity and concentration and stable quality. The treatment of the filling slurry in each step makes the filling slurry more uniform and of higher quality. The concentration of the red mud slurry and filling slurry in each step is more concentrated within the specified range, and the quality of the final filling slurry is more stable. Then, the filling slurry is transported to the goaf through a pipeline by a filling pump for filling and to effectively support the goaf.

[0028] In some embodiments, the red mud bottom flow and waste rock aggregate follow a positive correlation: the higher the waste rock content, the higher the red mud bottom flow concentration, the higher the overall mass concentration of the filling slurry, and the higher the strength of the final filling body. The overall mass concentration is calculated as (parts of dry red mud + parts of waste rock + parts of cementitious material) / (parts of dry red mud + parts of waste rock + parts of cementitious material + parts of water). The amount of cementitious material is calculated as (parts of dry red mud + parts of waste rock) / 15. For example, the red mud bottom flow has a component of 80 parts and a mass concentration of 55%. The red mud bottom flow consists of red mud and water. The dry red mud component in the red mud bottom flow is the product of the red mud bottom flow component and the mass concentration, that is, the red mud bottom flow contains 44 parts of dry red mud and 36 parts of water. When the waste rock component is 25 parts, the cementitious material component is 4.6 parts according to the above calculation method. According to the above calculation method for comprehensive mass concentration, the comprehensive mass concentration is 67.2%.

[0029] In some embodiments, filling slurries obtained using different raw material ratios are suitable for filling areas with different strength requirements; specifically, When the red mud underflow concentration is 55% and the red mud underflow is 80 parts, it contains 44.0 parts dry red mud, 36.0 parts water, 25 parts waste rock, 4.60 parts cementitious material, 73.60 parts total solids, and a comprehensive mass concentration of 67.2%. The slurry has excellent fluidity and is suitable for low-strength filling areas. When the red mud bottom flow concentration is 58% and the red mud bottom flow is 90 parts, it contains 52.2 parts dry red mud, 37.8 parts water, 33 parts waste rock, 5.68 parts cementing material, and a total solid phase of 90.88 parts, with a comprehensive mass concentration of 70.6%, and the fluidity and strength reach a medium balance. The red mud bottom flow concentration is 62%. When the red mud bottom flow is 100 parts, it contains 62.0 parts dry red mud, 38.0 parts water, 40 parts waste rock, 6.80 parts cementing material, and 108.80 parts total solids. The overall mass concentration is 74.1%. It has high strength and moderate fluidity, and is suitable for conventional high-strength backfilling. The red mud bottom flow concentration is 66%. When the red mud bottom flow is 110 parts, it contains 72.6 parts dry red mud, 37.4 parts water, 46 parts waste rock, 7.91 parts cementing material, and 126.51 parts total solids. The overall mass concentration is 77.2%. It has high strength but poor fluidity. With a red mud underflow concentration of 70%, when the red mud underflow is 120 parts, it contains 84.0 parts dry red mud, 36.0 parts water, 50 parts waste rock, 8.93 parts cementing material, and a total solid phase of 142.93 parts, with a comprehensive mass concentration of 79.9%. It has the highest strength but poor fluidity and is suitable for areas with special high strength requirements. Water-reducing agents or vibration measures are required during transportation. The above proportions fully cover the input range of 80-120 parts red mud underflow and 25-50 parts waste rock aggregate. As the waste rock content increases from 25 parts to 50 parts, the concentration and number of red mud underflows increase simultaneously, the dry red mud content increases from 44 parts to 84 parts, the water content remains stable at 36-38 parts, and the overall mass concentration of the filling slurry gradually increases from 67.2% to 79.9%. This achieves a four-level coverage that prioritizes fluidity at the low concentration end and strength at the high concentration end, meeting the differentiated requirements for fluidity and strength under different filling conditions.

[0030] In some embodiments, 80-120 parts of the red mud underflow with a mass concentration of 55-70% are fed into a mixer through a pipeline, including: the preferred mass concentration of the red mud underflow is 60-68%, more preferably 62%, 64%, 65% or 66%; the preferred number of parts of the red mud underflow is 85-110 parts, more preferably 90-106 parts, and even more preferably 94 parts, 98 parts, 100 parts or 102 parts.

[0031] In some embodiments, feeding 80-120 parts of the red mud bottom flow with a mass concentration of 55-70% into the mixer through a pipeline includes feeding 100 parts of the red mud bottom flow with a mass concentration of 65% into the mixer through a pipeline.

[0032] When preparing filling slurry, the preferred mass concentration of red mud underflow is 65%, and the preferred mass concentration of red mud underflow is 100 parts. 100 parts of red mud underflow with a mass concentration of 65% is a suitable amount for preparing filling slurry, which is convenient for mixing with raw materials such as waste rock and cementitious materials. This avoids the need to frequently switch the equipment used for preparing filling slurry when the mass concentration is too small, which would reduce the preparation efficiency. At the same time, it avoids the problem of too much raw material being input into the mixer when the mass concentration is too large, which would make it difficult for the mixer to mix the various raw materials in the preparation of filling slurry evenly. This improves the efficiency of filling slurry preparation and enhances the quality stability of the prepared filling slurry.

[0033] In some embodiments, the simultaneous feeding of 25-50 parts of waste stone aggregate into the mixer includes: preferably 30-45 parts of waste stone aggregate, more preferably 32-42 parts, more preferably 34-40 parts, and more preferably 36, 38 or 40 parts.

[0034] In some embodiments, the simultaneous feeding of 25-50 parts of waste rock aggregate into the mixer includes: simultaneously feeding 40 parts of waste rock aggregate into the mixer. Pure red mud slurry or fine-particle filling slurry is prone to bleeding and stratification when solidified into a filling body, leading to uneven strength of the filling body. An aggregate proportion in the range of 25-50 parts is sufficient to form a three-dimensional spatial constraint network. The preferred amount of waste rock aggregate is 40 parts, which avoids insufficient constraint on the red mud particles due to too little aggregate, and also prevents an increase in the porosity between the aggregate bridging formed by the waste rock aggregate due to too much aggregate, thereby improving the quality stability of the prepared filling slurry. Simultaneously, the rigid skeleton constructed by 40 parts of waste rock aggregate provides an excellent anchoring matrix for the hydration products of the cementitious material. The heat of hydration can be uniformly conducted by the waste rock aggregate, shortening the initial setting time of the prepared filling slurry and improving the efficiency of filling slurry preparation.

[0035] In some embodiments, the particle size of the waste rock aggregate is ≤15mm. When the particle size of the waste rock aggregate is greater than 15mm, it is easy to form a bridging effect during stirring or pumping, hindering the flow of red mud particles. Moreover, the larger the particle size, the faster the settling velocity of the waste rock aggregate, which can easily lead to increased segregation of the filling slurry when it solidifies into a filling body. By controlling the maximum particle size of the waste rock aggregate to less than or equal to 15mm, it is ensured that the waste rock aggregate and the red mud bottom flow form a cross-scale continuous gradation. The waste rock aggregate has a larger particle size relative to the red mud bottom flow, which improves the efficiency of the waste rock aggregate. The red mud bottom flow particles provide structural support and fill the pores between the waste rock aggregates, reducing the overall specific surface area of ​​the resulting filling slurry. This reduces the water requirement for the waste rock aggregates and red mud bottom flow particles, improving the stability of the prepared filling slurry's quality. Controlling the particle size of the waste rock aggregates to less than or equal to 15mm avoids unplanned downtime caused by blockages due to large waste rock aggregate particles. At the same time, the conveying pump does not need to overcome the resistance caused by large waste rock aggregate particles, reducing the energy consumption of the conveying pump and improving the efficiency of the filling slurry preparation process.

[0036] In some embodiments, feeding 4 to 10 parts of the gelling material into the mixer via a feeder includes: preferably 5 to 8 parts of the gelling material, more preferably 6 or 8 parts.

[0037] In some embodiments, feeding 4-10 parts of the cementitious material into the mixer via a conveyor includes feeding 6 parts of the cementitious material into the mixer via the conveyor. 4-10 parts of the cementitious material can balance the optimal window of reactivity and rheological controllability, avoiding high viscosity problems caused by excessive cementitious material. Preferably, 6 parts of the cementitious material can maximize the efficiency of the backfill-mining operation connection while ensuring reasonable initial setting time and early strength. At the same time, 6 parts of the cementitious material can provide appropriate hydration products, which can fill pores without causing structural defects, thereby improving the quality of the backfill slurry.

[0038] In some embodiments, before starting the mixer, the red mud and waste rock co-filling method further includes feeding 5-20 parts of the upper overflow water into the mixer via a delivery pump B to adjust the slurry concentration; the upper overflow water generated when the thickener thickens the red mud slurry is transported to the mixer via the delivery pump B, which can adjust the concentration of the filling slurry in the mixer. This is a key operation for dynamically adjusting the concentration of the filling slurry and achieving a low viscosity and high stability rheological state of the filling slurry. It is convenient to improve the quality and quality stability of the filling slurry, so that the prepared filling slurry can meet the requirements of long-distance transportation and can quickly lose water and solidify during the solidification stage to support the goaf.

[0039] In some embodiments, the step of feeding 5 to 20 parts of the overflow water into the mixer via pump B includes: the number of overflow water parts is preferably 8 to 16 parts, more preferably 10 to 15 parts, and even more preferably 12 or 14 parts.

[0040] In some embodiments, 65-80% of the red mud particles in the filling slurry have a particle size of less than 75 μm, and the waste rock aggregate has a particle size of 0.15-15 mm. If the content of red mud particles with a particle size of less than 75 μm is less than 65%, the filling of the gaps between the waste rock aggregate will be insufficient, which can easily lead to a high porosity of the filling slurry and insufficient strength of the formed filling body. If the content is greater than 80%, it can easily lead to a weakening of the skeleton formed by the waste rock aggregate, resulting in an increased risk of shrinkage and cracking of the filling body. Controlling the content of red mud particles with a particle size of less than 75 μm within the range of 65-80% makes the filling... The filling slurry prepared by the manufacturer has good crack resistance and can fully fill the gaps between waste rock aggregates, thus improving the quality of the filling slurry. The proportion of red mud fine particles with a particle size of less than 75μm, accounting for 65-80%, can provide a sufficient lubricating film to coat the surface of the waste rock aggregate, reducing the frictional resistance of the pipeline wall during the transportation of the filling slurry and improving the efficiency of the filling operation. The 65-80% of red mud particles with a particle size of less than 75μm, together with the waste rock aggregate with a particle size of 0.15-15mm, form a low-viscosity and high-density optimized gradation system, which improves the viscosity and rheological properties of the filling slurry and enhances its quality.

[0041] Example 2 See Figure 2 This application provides a red mud and waste rock co-filling process system for implementing the red mud and waste rock co-filling method described in any one of the embodiments, including: a red mud thickening and settling unit 1, a waste rock aggregate preparation unit 2, a filling slurry preparation unit 3, an overflow water collection and reuse unit 4, and a filling and conveying unit 5. The red mud thickening and settling unit 1 includes a red mud slurry storage tank 11, a conveying pump A12, and a thickener 13; the red mud slurry storage tank 11 is provided with a dilution water addition port 111; the outlet A112 of the red mud slurry storage tank 11 is connected to the feed inlet A131 of the thickener 13 through the conveying pump A12. The waste rock aggregate preparation unit 2 is used to process waste rock into waste rock aggregate. The filling slurry preparation unit 3 is used to mix and stir the input overflow water, cementing material, red mud bottom flow and waste stone aggregate to prepare filling slurry; The overflow water collection and reuse unit 4 includes an overflow water collection tank 41 and a transfer pump B42; the inlet C411 of the overflow water collection tank 41 is connected to the upper overflow port 133 of the thickener 13, and the outlet B412 of the overflow water collection tank 41 inputs the overflow water into the filling slurry preparation unit 3 through the transfer pump B42; the outlet C413 of the overflow water collection tank 41 is also connected to the dilution water addition port 111. The filling and conveying unit 5 is connected to the filling slurry preparation unit 3 and is used to convey the filling slurry to the area to be filled.

[0042] The dilution water inlet 111 on the red mud slurry storage tank 11 is used to add dilution water. The filter cake and dilution water are mixed and diluted in the red mud slurry storage tank 11 to dilute the filter cake to a red mud slurry of mass concentration A. This is beneficial for the agglomeration structure of the filter cake to disperse, and also facilitates transportation and metering. The red mud slurry in the red mud slurry storage tank 11 is pumped from the outlet A112 to the feed inlet A131 of the thickener 13 through the delivery pump A12, and enters the thickener 13 for thickening treatment. At the same time, flocculant is added to the thickener 13, and the red mud slurry is flocculated and settled in the thickener 13 using the flocculant.

[0043] In the red mud slurry storage tank 11, the filter cake has been diluted to a red mud slurry of mass concentration A. The mixture is then further treated by thickener 13 to perform flocculation sedimentation and solid-liquid separation, resulting in overflow water and red mud underflow of mass concentration B. The concentration of the red mud underflow is stable and controllable, which facilitates the improvement of the quality and stability of the filling slurry. Moreover, the processing capacity of thickener 13 is much greater than that of intermittent filter press, realizing continuous concentration treatment and continuous production of red mud slurry, and improving the operating efficiency of the filling system.

[0044] Waste rock aggregate preparation unit 2 processes mine waste rock through crushing and screening into waste rock aggregate, which is then fed into filling slurry preparation unit 3. The waste rock aggregate forms a continuous complementary gradation with the red mud bottom flow particles. The waste rock aggregate particles serve as a skeleton and are incorporated into the viscoplastic continuum of the red mud bottom flow. The shearing action between the waste rock aggregate particles breaks down the particle agglomeration structure in the red mud bottom flow, making it easier to disperse the red mud during the mixing process to form the filling slurry. This solves the problems of easy agglomeration and poor mixing uniformity when red mud bottom flow is mixed alone. The incorporation of waste rock aggregate can reduce the overall viscosity and yield stress of the filling slurry, improve the viscosity and fluidity of the filling slurry, facilitate the improvement of the quality of the filling slurry, enhance the internal structure of the filling body formed by the filling slurry, and optimize the strength of the filling body.

[0045] Overflow water, cementing material, red mud bottom flow, and waste rock aggregate are input into filling slurry preparation unit 3. The filling slurry preparation unit 3 is used to mix and stir the input overflow water, cementing material, red mud raw material, and waste rock aggregate evenly to obtain filling slurry. Filling and conveying unit 5 outputs the filling slurry prepared by filling slurry preparation unit 3 from the discharge port A36 of filling slurry preparation unit 3 and conveys it to the area to be filled for filling.

[0046] In the process of preparing filling slurry using waste rock, the waste rock aggregate not only serves as the skeleton material of the filling body, providing strength support for the final filling body, but also, during the mixing process in filling slurry preparation unit 3, utilizes the waste rock aggregate to form a continuous interparticle physical shearing action on the red mud bottom flow in the mixing flow field, breaking up the particle agglomeration structure in the red mud bottom flow. This solves the problem of easy agglomeration when red mud bottom flow is mixed alone, shortens the mixing time, and improves the slump of the filling slurry. The waste rock aggregate is not just a passive filler, but becomes an active process aid in the preparation of filling slurry, which can improve the quality stability of the filling slurry. Compared with the red mud filling slurry without waste rock aggregate, the final filling slurry has significantly improved mixing uniformity, meeting the fluidity requirements of pumping construction. After the red mud bottom flow, waste rock aggregate, cementing material, and overflow water components are fully mixed to prepare a homogeneous and stable filling slurry, the filling slurry is output for filling.

[0047] Overflow water collection and reuse unit 4 collects the overflow water generated from red mud sedimentation through the upper overflow port 133 of thickener 13 to overflow water collection tank 41. The outlet C413 of overflow water collection tank 41 is connected to dilution water addition port 111, and at least a portion of the overflow water is recycled to dilution water for use. The overflow water in overflow water collection tank 41 is pumped to filling slurry preparation unit 3 by transfer pump B42 for filling slurry preparation, reducing the discharge of overflow water and realizing the resource utilization of process wastewater.

[0048] In some embodiments, a feed pipe 17 is further provided between the outlet A112 and the inlet A131, and the feed pipe 17 is provided with a flocculant addition port 171 and a mixing water addition port 172; the outlet C413 of the overflow water collection tank 41 is also connected to the mixing water addition port 172; by setting the flocculant addition port 171 and the mixing water addition port 172 on the feed pipe 17, the flocculant and the mixing water are premixed with the red mud slurry on the feed pipe 17 to form a mixture, which is beneficial to increase the mixing uniformity of the flocculant and the red mud slurry and improve the production efficiency. To ensure the quality stability of the filling slurry, the red mud slurry with premixed flocculant is continuously flocculated, settled, and separated in the thickener 13, thereby improving the settling efficiency of the red mud slurry. The outlet C413 of the overflow water collection tank 41 is connected to the mixing water addition port 172, and at least a portion of the overflow water is recycled to dilution water and / or mixing water for use. The remaining portion of the overflow water in the overflow water collection tank 41 is pumped to the filling slurry preparation unit 3 for filling slurry preparation, completely cutting off the overflow water discharge in the traditional process and realizing zero discharge of process wastewater and full resource utilization.

[0049] In some embodiments, the filling slurry preparation unit 3 is provided with an inlet 35 for inputting overflow water, red mud bottom flow, waste rock aggregate and cementitious material preparation water, a red mud inlet 32, an aggregate inlet 33 and a cementitious material inlet 34 respectively; each inlet and inlet of the filling slurry preparation unit 3 is equipped with a metering and regulating component; the water inlet 35 is matched with the feeding sequence of the cementitious material inlet 34; the feeding sequence of the red mud inlet 32 ​​and the aggregate inlet 33 is matched.

[0050] Each feed inlet and water inlet of the filling slurry preparation unit 3, namely the red mud feed inlet 32, the aggregate feed inlet 33, the cementitious material feed inlet 34, and the preparation water inlet 35, is equipped with a metering and regulating component to ensure that the water inlet 35 matches the feed sequence of the cementitious material feed inlet 34, and the feed sequence of the red mud feed inlet 32 ​​and the aggregate feed inlet 33. This ensures that the amounts of red mud feed, waste rock aggregate feed, cementitious material feed, and preparation water feed can be mixed and stirred evenly according to the designed component ratio to form a filling slurry with good fluidity and stability. Red mud underflow and waste rock aggregate are simultaneously fed into the filling slurry preparation unit 3 from the red mud inlet 32 ​​and the aggregate inlet 33, respectively. Preparation water and cementitious materials can be simultaneously fed into the filling slurry preparation unit 3 according to the ratio and pre-dispersed. During the stirring process in the filling slurry preparation unit 3, the waste rock aggregate forms a continuous interparticle shearing action on the red mud underflow in the stirring flow field to break up the particle agglomeration structure in the red mud underflow, while improving the mixing uniformity of the cementitious materials and avoiding the formation of unhydrated dry agglomerates of cementitious materials. The red mud underflow and waste rock aggregate are mixed with the cementitious materials to complete the mixing and stirring, improve the uniformity of the filling slurry preparation, and thus improve the quality and quality stability of the filling slurry.

[0051] In some embodiments, the red mud slurry storage tank 11 is equipped with a stirring device A, and the filling slurry preparation unit 3 includes a mixer B31. The stirring device A is an adjustable frequency stirring device, and the rotation speed of the stirring device A is 0~25 rpm; the mixer B31 is a fixed frequency mixer, and the rotation speed of the mixer B31 is 40~60 rpm.

[0052] The stirring device A in the red mud slurry storage tank 11 stirs the filter cake at a speed of 0~25 rpm while diluting it, so that the diluted filter cake slurry is in a slightly suspended state, preventing the filter cake from settling to the bottom, making the diluted red mud slurry homogeneous and stable, and avoiding the red mud particles from settling into agglomerated structures. The stirring device A is an adjustable frequency stirring device, and the upper limit of the speed is limited to 25 rpm, which provides a weak but continuous disturbance, so that the diluted red mud slurry is always maintained in a state that will not lose its structural viscosity due to excessive shearing, nor will it solidify into lumps due to complete settling. This facilitates the improvement of the uniformity of the red mud slurry and improves the quality and quality stability of the filling slurry.

[0053] The mixer B31 in the filling slurry preparation unit 3 rotates at 40-60 rpm, which can disperse the red mud bottom flow without crushing the waste stone aggregate or causing excessive wear on the equipment. The mixer B31 is a fixed-frequency mixer, which means that the cumulative shear work of each batch of filling slurry is constant. Compared with the operation variable interference that may be caused by variable frequency speed regulation, the fixed frequency and appropriate speed ensure the engineering certainty of obtaining the filling slurry with the expected viscosity according to the given ratio. This can improve the quality stability of the filling slurry, greatly reduce the on-site commissioning time, and improve the efficiency of filling operations.

[0054] In some embodiments, the red mud inlet 32, aggregate inlet 33, cementitious material inlet 34, and preparation water inlet 35 of the filling slurry preparation unit 3 are specifically provided on the cylinder of the mixer B31. That is, the cylinder of the mixer B31 is provided with preparation water inlet 35, red mud inlet 32, aggregate inlet 33, and cementitious material inlet 34. The raw materials for preparing the filling slurry are fed into the mixer B31 from each inlet and water inlet for stirring to prepare the filling slurry evenly.

[0055] In some embodiments, the thickener 13 is a deep cone thickener, which has a deeper settling layer and a longer settling path, allowing the solid components in the red mud slurry to settle more fully, thus improving solid-liquid separation efficiency. It can process red mud underflow with higher concentration and lower water content, facilitating the output of red mud underflow with the target concentration according to the actual filling slurry preparation requirements, thereby improving the accuracy of the filling slurry concentration. Furthermore, the large cone angle at the bottom of the deep cone thickener is beneficial for the compression and concentration of solid particles, making the red mud underflow more stable. A stable slurry concentration is more conducive to the continuity and stability of subsequent filling operations, thereby improving the overall efficiency of filling slurry preparation and filling operations. Utilizing the structural advantages of the deep cone thickener, its settling effect can reduce dependence on flocculants, thus lowering the material cost of preparing filling slurry to a certain extent.

[0056] In some embodiments, the thickener 13 is a center-driven type, the thickener 13 is provided with a center drive shaft, the cone angle of the thickener 13 is 30°~45°, the thickener 13 is provided with a stirring rake frame, the stirring rake frame is fixedly connected to the center drive shaft of the thickener 13, and the stirring rake frame is driven to rotate by the center drive shaft of the thickener 13. When the flocculant is added to the red mud slurry and enters the thickener 13, the stirring rake frame promotes the compression and drainage of flocs, promotes the sedimentation of the red mud slurry to form red mud bottom flow and overflow water.

[0057] In some embodiments, after the flocculant is added to the thickener 13, the thickener 13 is slowly stirred at a speed of 0.15 r / min using a rake frame to promote the compression and drainage of flocs and improve the flocculation and sedimentation efficiency of the red mud slurry.

[0058] In some embodiments, the upper part of the thickener 13 is also provided with an annular overflow weir. The annular overflow weir is arranged around the top circumference inside the thickener 13, which can make the clarified water to be overflowed evenly along the entire circumference, and avoid the red mud slurry that has not settled sufficiently being carried out of the thickener 13 due to excessive local flow velocity.

[0059] In some embodiments, the traditional filter press method requires filter pressing first, followed by transfer and feeding. However, the process of using a thickener 13 to replace the intermittent filter press for filling slurry preparation can continuously supply materials and achieve continuous concentration of red mud slurry without the need for filter pressing and transfer time. The underflow concentration is stably controlled at about 55~70%. It is understood that, based on the changes in the particle size distribution of red mud, the actual red mud underflow concentration may fluctuate by ±2% from the above concentration range, which is within an acceptable range. Using the thickener 13 to prepare filling slurry increases the processing capacity by more than 50% compared to the filter press process, meeting the needs of large-scale filling operations.

[0060] In some embodiments, the red mud thickening and settling unit 1 further includes a flow meter A14 and a concentration meter 15; the flow meter A14 and the concentration meter 15 are located between the bottom underflow outlet 132 of the thickener 13 and the red mud inlet 32 ​​of the filling slurry preparation unit 3. Based on the data from the flow meter A14 and the concentration meter 15, the input amount of red mud slurry and flocculant is adjusted so that the thickener 13 can perform sufficient settling treatment on the red mud slurry.

[0061] In some embodiments, a red mud underflow pump 16 is provided after the bottom underflow outlet 132 and before the flow meter A14 and the concentration meter 15; the red mud underflow pump 16 delivers the red mud underflow pump 16 generated in the thickener 13 to the filling slurry preparation unit 3 for filling slurry preparation.

[0062] In some embodiments, a reuse pipe is provided between the delivery pump B42 and the preparation water inlet 35. A flow metering and regulating component 43 is provided on the reuse pipe. The flow metering and regulating component 43 regulates the amount of overflow water fed in according to the real-time demand of filling slurry preparation. The overflow water output by the thickener 13 has a solids content of less than 300 ppm and contains sodium hydroxide and sodium aluminate components. The overflow water is sent into the preparation water inlet 35 of the filling slurry preparation unit 3 through the reuse pipe.

[0063] A flow metering and regulating component 43 is installed on the reuse pipeline to achieve on-demand water supply and dynamically adjust the water supply rate. This allows for precise flow control of the overflow water entering the filling slurry preparation unit 3, ensuring that the concentration and quality of the filling slurry prepared in the filling slurry preparation unit 3 meet the filling requirements. All overflow water with a solids content of <300ppm generated from the thickening and settling of red mud is directly reused in the preparation of filling slurry, which can avoid the environmental risks caused by the discharge of alkaline wastewater, and achieve the process reduction of wastewater discharge, wastewater recycling, and the conservation of fresh water resources.

[0064] By synergistically activating the skeletal function of waste rock aggregate and the potential cementitious activity of red mud, the amount of cementitious material can be reduced while maintaining the strength of the filling body formed by the filling slurry at ≥3MPa after 28 days of solidification. The residual sodium hydroxide and sodium aluminate components in the overflow water form a synergistic activation mechanism with the calcium ions generated by the hydration of the cementitious material. The sodium hydroxide in the overflow water provides a highly alkaline environment, promoting the dissolution of the silica-alumina phase in the red mud, releasing aluminate and silicate ions, and activating the potential cementitious activity of the red mud. The sodium aluminate in the red mud bottom flow and overflow water replenishes the active aluminum source, participating in gel formation. Meanwhile, the calcium ions provided by the hydration of the cementitious material react with the calcium ions generated by the cementitious material in the alkaline environment. The dissolved and released aluminate and silicate ions undergo a condensation reaction to generate calcium-alkali aluminosilicate gel. This mixed gel structure containing calcium-alkali aluminosilicate is denser and more stable than the hydrated calcium silicate or sodium aluminosilicate hydrate activated by soda ash, which can improve the mechanical properties and durability of the filling material formed by the filling slurry and enhance the quality of the filling material. During the stirring process in the filling slurry preparation unit 3, the sodium hydroxide and sodium aluminate components in the overflow water are used to synergistically activate the potential gelling activity of red mud with the gelling material, which can reduce the amount of gelling material used and solve the problem of high cost caused by the large amount of gelling material used in the preparation process of red mud-based filling slurry.

[0065] In some embodiments, the flow metering and regulating component 43 specifically comprises an overflow water flow meter B431 and an overflow water regulating valve B432. The overflow water flow meter B431 is installed between the delivery pump B42 and the preparation water inlet 35. The opening of the overflow water regulating valve B432 is adjusted based on the data from the overflow water flow meter B431 as a reference, thereby controlling the amount of overflow water required to fill the filling slurry preparation unit 3.

[0066] In some embodiments, the waste rock aggregate preparation unit 2 includes a waste rock silo 21, a crusher 22, a screening machine 23, and a waste rock aggregate silo 24 connected in sequence; the discharge port of the oversize material of the screening machine 23 is connected to the feed port of the crusher 22 to form a closed-circuit crushing and repeated screening; the undersize material of the screening machine 23 is waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles; a metering feed control component 25 is provided at the bottom of the waste rock aggregate silo 24, and the waste rock aggregate is transported to the filling slurry preparation unit 3 via the metering feed control component 25.

[0067] Waste rock in waste rock bin 21 is transported to crusher 22 for crushing to produce waste rock aggregate. Screening machine 23 screens the pre-crushed waste rock aggregate. The undersize material of screening machine 23 is waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. The oversize material of screening machine 23 is transported from the discharge port of screening machine 23 to the feed port of crusher 22 for crushing, forming a closed-circuit crushing and repeated screening. This actively makes the particle size of waste rock aggregate form a continuous complementary gradation with the distribution of red mud bottom flow particles, rather than simply crushing the waste rock to below a certain maximum particle size. This ensures that the waste rock aggregate entering the filling slurry preparation unit 3 meets the particle size requirements. The metering and feeding control component 25 at the bottom of waste rock aggregate bin 24 controls the amount of waste rock aggregate entering the filling slurry preparation unit 3, which helps to improve the quality of the filling slurry.

[0068] In some embodiments, the metering and feeding control component 25 is a metering belt scale, which is used to transport waste stone aggregate to the filling slurry preparation unit 3. During the transport, the transported waste stone aggregate is metered and weighed to ensure that the filling slurry is prepared according to the specified ratio. It can be understood that, depending on the processing efficiency of waste stone aggregate, when a large amount of waste stone aggregate is generated and the filling slurry preparation unit 3 cannot completely consume the waste stone aggregate generated in real time by the screening machine 23, the waste stone aggregate is stored in the waste stone aggregate bin 24. When transporting the waste stone aggregate to the filling slurry preparation unit 3, it can be transported from the undersize outlet of the screening machine 23 to the filling slurry preparation unit 3, or from the bottom of the waste stone aggregate bin 24 to the filling slurry preparation unit 3.

[0069] In some embodiments, the waste stone aggregate under the screen of the screening machine 23 has a particle size of ≤15mm, while the waste stone aggregate with a particle size greater than 15mm is returned to the crusher 22 as the oversize material of the screening machine 23 for further crushing until the waste stone aggregate with a particle size of ≤15mm can be screened out by the screening machine 23.

[0070] In some embodiments, the proportion of red mud fine particles with a particle size of less than 75 μm is relatively high, which forms a good particle size distribution with waste rock aggregate with a particle size of 0.15~15 mm, thereby improving the compactness and mechanical properties of the filling body formed by the filling slurry and improving the quality of the filling slurry.

[0071] In some embodiments, the red mud waste rock co-filling process system further includes: a cementitious material storage and metering unit 6, which includes a cementitious material storage silo 61, a feeder 62, and a conveyor 63; the bottom outlet of the cementitious material storage silo 61 is connected to the inlet of the conveyor 63 through the feeder 62, and the outlet of the conveyor 63 is connected to the cementitious material inlet 34 of the filling slurry preparation unit 3; the cementitious material is conveyed from the bottom outlet of the cementitious material storage silo 61 to the filling slurry preparation unit 3 through the feeder 62. Unit 3 utilizes a feeder 62 to measure the amount of cementitious material during conveying, achieving continuous and quantitative conveying of the cementitious material. This allows for dynamic and precise control of the cementitious material ratio, avoiding material loss caused by manual feeding errors or dust, and ensuring accurate dosage of cementitious material during the filling slurry preparation process. This, in turn, improves the quality and stability of the filling slurry. During the process of conveying the cementitious material to the filling slurry preparation unit 3, it is transported by a conveyor 63 to prevent external moisture from entering the cementitious material storage silo 61 and causing the cementitious material to solidify and fail.

[0072] In some embodiments, the feeder 62 is a screw metering feeder. The screw metering feeder can achieve precise metering and continuous feeding of solid materials by adjusting the screw speed, which is beneficial for controlling the amount of cementitious material required to prepare filling slurry and improving the accuracy of the concentration of the prepared filling slurry. The conveyor 63 is a double-pipe screw conveyor. The double-pipe screw conveyor adopts a double-screw structure, which can transport materials synchronously and prevent material accumulation and blockage. The screw structure is beneficial for breaking up agglomerated cementitious materials during the conveying process, improving the uniformity of cementitious materials entering the mixer B31, thereby improving the uniformity of the prepared filling slurry and thus improving the quality stability of the filling slurry.

[0073] In some embodiments, the filling and conveying unit 5 includes a filling pump 51 and a filling and conveying pipeline. The inlet of the filling pump 51 is connected to the outlet of the filling slurry preparation unit 3. The end of the filling and conveying pipeline extends to the underground goaf or the open-pit area to be filled. The filling pump 51 is used to convey the prepared filling slurry to the area to be filled through the filling and conveying pipeline. The outlet of the filling pump 51 is connected to the inlet of the filling and conveying pipeline. The outlet of the filling and conveying pipeline extends to the area to be filled, thereby filling the underground goaf or the open-pit area to be filled.

[0074] In some embodiments, the mixer B31 is a twin-shaft forced mixer. The red mud inlet 32, aggregate inlet 33, cementitious material inlet 34, and preparation water inlet 35 are located at the upper part of the mixer B31. The bottom outlet of the mixer B31 is connected to the inlet of the filling pump 51. The twin-shaft forced mixer B31 has two counter-rotating mixing shafts and is equipped with high-efficiency mixing blades, which can forcibly shear, tumble, and mix the materials, significantly improving the mixing uniformity and efficiency. Compared with ordinary mixing equipment, it mixes more thoroughly and with higher uniformity, which facilitates the improvement of the quality of the filling slurry. At the same time, it helps to reduce the phenomenon of excessively high local viscosity of the filling slurry, thereby improving the overall rheological properties and increasing the filling efficiency. The inlets are located at the mixer B31. The upper part of mixer B31 facilitates the uniform entry of various raw materials for preparing filling slurry into the mixing zone under gravity, reducing material segregation and accumulation. This ensures that various materials are fully contacted and initially mixed at the beginning of the mixing process, laying a good foundation for subsequent efficient mixing. It also helps to form a uniform, fluid filling slurry, reduce the viscosity of the filling slurry, and improve filling stability. The bottom discharge port of mixer B31 ensures that the mixed slurry is quickly and thoroughly discharged under gravity assistance, reducing the risk of residue and blockage and improving discharge efficiency. At the same time, mixer B31 is directly connected to filling pump 51, which can achieve seamless connection from mixing to conveying of slurry, avoiding segregation or viscosity increase of slurry in the intermediate stage, thereby ensuring the continuity and stability of the filling process and improving the overall operation efficiency.

[0075] Example 3 See Figure 3 This application provides a method for co-filling red mud and waste rock, comprising: S100. The filter cake is mixed and diluted with dilution water to obtain red mud slurry with a mass concentration of A. S101. The red mud slurry, flocculant and conditioning water are premixed to obtain a mixture; S102. The mixture is subjected to flocculation sedimentation and solid-liquid separation to obtain red mud bottom flow and overflow water with mass concentration B respectively; wherein, at least a portion of the overflow water is recycled to the dilution water and / or the blending water; S103. The waste rock is crushed and screened to obtain waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. S104. Premix the gelling material with the remaining portion of the overflow water to form a gelling material suspension; S105. The cementitious material suspension, red mud bottom flow and waste stone aggregate are mixed and stirred to obtain a homogeneous and stable filling slurry. S106. The filling slurry is transported to the area to be filled to complete the filling operation.

[0076] In this embodiment, the filter cake with low moisture content is mixed and diluted with dilution water to obtain a red mud slurry with a mass concentration of A. This facilitates the dispersal of the filter cake's agglomerated structure and makes it easier to transport and measure. After the agglomerated and lumpy structure of the filter cake disperses in the dilution water, the particle structure of the red mud is evenly distributed in the red mud slurry, which helps to improve the uniformity of stirring and facilitates thorough mixing with the flocculant, thereby improving the quality of the filling slurry. The diluted red mud slurry does not contain agglomerated filter cake structures, which can avoid local agglomeration and uneven viscosity distribution of the filling slurry during preparation, as well as the filling slurry sticking to or blocking pipes during transportation.

[0077] Flocculants are more easily dissolved and activated in dilute solutions. Premixing can improve the efficiency of flocculants. Adding overflow water to the mixing water and premixing it with flocculants and red mud slurry promotes the uniform dispersion of flocculants and uniform mixing with red mud slurry. This facilitates the flocculant to fully contact and react with the red mud slurry, promoting flocculation and sedimentation. It also helps to obtain stable red mud bottom flow and overflow water during flocculation sedimentation and solid-liquid separation treatment, thereby improving the stability of the quality of the filling slurry.

[0078] The mixture was subjected to flocculation sedimentation and solid-liquid separation to obtain overflow water and red mud bottom flow with mass concentration B, respectively. Filter cakes with different moisture contents were first diluted to red mud slurry with mass concentration A to improve the concentration stability of the raw materials for preparing filling slurry. Further sedimentation treatment was then carried out to obtain red mud bottom flow with mass concentration B, which further improved the concentration stability of the red mud bottom flow used to prepare filling slurry, thereby improving the quality stability of filling slurry.

[0079] The rheological properties of filling slurry depend on particle size distribution. High porosity due to the packing of fine red mud particles results in high viscosity and low fluidity, which is unfavorable for preparing homogeneous and stable filling slurry. By crushing and screening waste rock from mining, a waste rock aggregate with a continuous complementary gradation to the red mud bottom flow particles is obtained. During the preparation of filling slurry, the particle size distribution of the waste rock aggregate and the fine red mud particles is nested to achieve maximum packing density, reduce porosity, and thus reduce the required overflow water volume. This significantly reduces the slurry viscosity while maintaining fluidity. The use of waste rock as a skeleton support in the filling slurry reduces direct contact between red mud particles, weakens the tendency to agglomerate, improves the quality stability of the filling slurry, enhances the early strength and stability of the filling body, and improves the efficiency of filling operations.

[0080] Although the overflow water generated from the thickening process of the mixture is clarified, it is still highly alkaline, with a pH value of 12.1-13.0, and contains trace amounts of colloids and metal ions such as aluminum, iron, calcium, and magnesium. Direct discharge poses an environmental risk. At least a portion of the overflow water is used as dilution water for the filter cake and as blending water for premixing with red mud slurry and flocculants, thereby reducing the consumption of fresh water resources and saving fresh water costs. The remaining portion of the overflow water is used to premix with cementitious materials to form a cementitious material suspension, achieving zero wastewater discharge and fully utilizing the overflow water. Using the overflow water in the preparation of filling slurry not only reduces the discharge of alkaline and heavy metal-containing wastewater at the source, preventing the discharge of harmful substances that pollute the ecological environment, effectively controlling ecological environmental pollution and protecting the environment, but also improves the quality and stability of the prepared filling slurry.

[0081] The remaining portion of the overflow water and the cementitious material are fed into a mixing device for pre-dispersion mixing. After pre-dispersion mixing, a uniform cementitious material suspension is prepared, which improves the mixing uniformity of the cementitious material in the filling slurry and improves the quality of the prepared filling slurry. After mixing the waste rock aggregate with the red mud bottom flow, the viscosity of the red mud bottom flow can be reduced. The cementitious material suspension is mixed with the red mud bottom flow and the waste rock aggregate that meets the continuous complementary gradation requirements to obtain a homogeneous and stable filling slurry, which facilitates the improvement of the quality stability of the filling slurry.

[0082] During the mixing and stirring process of the cementitious material suspension, red mud bottom flow, and waste rock aggregate, the waste rock aggregate exerts a continuous interparticle physical shearing effect on the red mud bottom flow in the stirring flow field, breaking up the particle agglomeration structure in the red mud bottom flow, and obtaining a homogeneous and stable filling slurry. This shortens the stirring time and improves the slump of the filling slurry. Compared with the red mud filling slurry without waste rock aggregate, the stirring uniformity is significantly improved, meeting the fluidity requirements for pumping construction. After the red mud bottom flow, waste rock aggregate, cementitious material, and overflow water components are fully stirred to prepare a homogeneous and stable filling slurry, the filling slurry is transported to the area to be filled to complete the filling operation.

[0083] In some embodiments, the filter cake has a moisture content of 10-25%, a mass concentration A of 20-40%, and a mass concentration B of 55-70%. The filter cake is first diluted to a mass concentration of 20-40% to ensure that the red mud particles in the filter cake are evenly dispersed in the red mud slurry and to avoid clumping. After obtaining the mixture, the mixture is subjected to flocculation sedimentation and solid-liquid separation to obtain a red mud underflow with a mass concentration of 55-70%. The filter cake, which has unstable moisture content and is prone to clumping, is first diluted and its mass concentration is controlled. Then, sedimentation and solid-liquid separation are performed and the concentration of the red mud underflow is controlled to improve the quality stability of the filling slurry.

[0084] In some embodiments, based on a filter cake of 100 kg with a moisture content of 20%, adding fresh dilution water to dilute it to obtain a red mud slurry with a mass concentration of 20% requires adding 300 kg of fresh water. Thickening the red mud slurry in a thickener to a red mud underflow with a mass concentration of 60% will output approximately 266 kg of overflow water. At least a portion of the overflow water is reused and added to the dilution water and blending water, while the remaining portion is reused and directly fed into the mixing equipment for preparing the filling slurry. Reusing all the overflow water can save approximately 88% of fresh water, reducing the consumption of fresh water resources, saving fresh water resource costs, and fully utilizing the overflow water, thereby reducing the discharge of alkaline and heavy metal-containing wastewater from the source.

[0085] In some embodiments, the crushing and screening of waste rock includes: processing waste rock generated from mining using a closed-circuit crushing and screening process; in the closed-circuit crushing and screening process, the coarse particles on the screen after screening are returned to the crusher for further crushing.

[0086] In the closed-circuit crushing and screening process, a crusher is used to crush waste rock to produce waste rock aggregate. The waste rock aggregate is then screened using screening equipment. Waste rock aggregate that meets the screening particle size requirements is transported to the filling slurry preparation unit for mixing. Waste rock aggregate with coarser particle size on the screen that does not meet the screening particle size requirements is recycled back to the crusher for further crushing until the particle size required by the screening process is met. This results in waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. Using this waste rock aggregate to prepare filling slurry helps to improve the concentration of the filling slurry, improve the mixing uniformity of the filling slurry, and enhance the quality stability of the filling slurry.

[0087] In some embodiments, the components of the filling slurry are proportioned by weight as follows: 80-120 parts of the red mud bottom flow with a mass concentration of 55-70%, 5-20 parts of the overflow water, 25-50 parts of the waste rock aggregate, and 4-10 parts of the cementing material.

[0088] When the concentration of red mud underflow is less than 55%, the high water content leads to an increase in the water content of the filling slurry. This not only reduces the solids content of the red mud underflow but may also dilute the prepared filling slurry, affecting the pumping volume. More cementing material is needed to increase the concentration of the filling slurry, increasing the cost of cementing material. Furthermore, for larger amounts of cementing material, more mixing time is required to achieve uniform mixing and prevent clumping. This increases the energy consumption required to prepare the filling slurry, hindering the improvement of filling operation efficiency. When the concentration of red mud underflow is greater than 70%, the interaction between red mud underflow particles... Increased viscosity leads to a significant rise in internal friction and viscosity, decreased fluidity, difficulty in mixing, and even uneven mixing and clumping, affecting the uniformity and transport stability of the slurry, as well as the quality and stability of the prepared filling slurry. Controlling the concentration of red mud underflow between 55% and 70% is the critical range to ensure fluidity and pumpability. It can reduce the overall moisture content of the slurry while ensuring sufficient dispersion of red mud underflow particles, thereby controlling the viscosity within a reasonable range, improving the fluidity and pumpability of the slurry, which is beneficial to improving filling efficiency, construction continuity, and the quality stability of the filling slurry.

[0089] The water used to prepare the filling slurry is the overflow water from the thickener. The overflow water contains alkaline components such as sodium hydroxide and sodium aluminate. The gel is generated by the reaction of the cementitious material with the alkaline components and sodium aluminate in the overflow water to form a synergistic activation mechanism. This fully utilizes the useful resources in the overflow water, reduces the cost of cementitious materials, and reduces the environmental pollution caused by overflow water discharge. When the amount of overflow water is less than 5 parts, the alkalinity is insufficient, resulting in insufficient activation of the silica-alumina phase in the red mud, less gel formation, and an inability to effectively improve the quality of the prepared filling slurry and reduce the amount of cementitious material used. When the amount of overflow water exceeds 20 parts, the proportion of solid phase in the filling slurry decreases, prolonging the setting time of the filling slurry. It may also introduce excessive sodium ions, leading to harmful expansion or efflorescence during the later stages of filling slurry solidification. Limiting the amount of overflow water to 5-20 parts maintains an alkaline environment during filling slurry preparation and matches it with the proportion of cementitious materials. This improves the quality stability of the prepared filling slurry, makes full use of the useful resources in the overflow water, and prevents environmental pollution.

[0090] When the amount of red mud underflow with a mass concentration of 55-70% is less than 80 parts, the proportion of red mud is too low, which may lead to insufficient solid content in the prepared filling slurry, reduced compaction of the filling body formed by the slurry, affecting the later strength development, and failing to fully utilize red mud resources. When the amount of red mud underflow is higher than 120 parts, the content of fine particles in the prepared filling slurry will be too high, increasing the viscosity of the filling slurry, reducing fluidity, and easily causing problems such as uneven mixing, high conveying resistance, and pipe blockage. More waste stone aggregate needs to be added, making it difficult to adjust the proportion of other raw materials accordingly, which may result in the concentration of the prepared filling slurry not meeting the quality requirements. Controlling the amount of red mud underflow at 80-120 parts ensures the fluidity of the slurry during mixing while reasonably controlling the viscosity of the slurry during mixing, so that the red mud underflow and waste stone aggregate form a good particle size distribution, improving the homogeneity and pumping effect of the prepared filling slurry, and improving the quality stability of the filling slurry.

[0091] By incorporating 25-50 parts of waste rock aggregate during the preparation of the filling slurry, the shearing action of the waste rock particles can break down the red mud agglomerates, solving the technical problems of easy clumping and poor uniformity when red mud bottom flow is stirred alone. This reduces the viscosity of the filling slurry, improves its quality, increases the slump of the filling slurry to 250-270 mm, shortens the mixing time, and improves the efficiency of filling construction. When the waste rock aggregate is less than 25 parts, the improvement effect on the viscosity of the filling slurry is not significant; when it is more than 50 parts, the filling slurry segregates, the pumping resistance increases, and the risk of pipe blockage increases.

[0092] When the amount of cementitious material is less than 4 parts, the strength of the filling body formed by the filling slurry is insufficient. When the amount of cementitious material is more than 10 parts, the cost of cementitious material increases significantly, and the activity of red mud is not fully utilized. Through the synergistic effect of the above component ratios, the slump of the formed filling slurry is ensured to be greater than or equal to 250 mm, ensuring fluidity. At the same time, the strength of the filling body is ensured to reach ≥3 MPa after 28 days of solidification, ensuring the performance and quality of the formed filling slurry. This solves the problem of performance degradation of filling slurry caused by mismatch in the proportions of the components required for synergistic effect in the preparation of filling slurry.

[0093] In some embodiments, the step of premixing the gelling material with the remaining portion of the overflow water to form a gelling material suspension includes: inputting the gelling material and the remaining portion of the overflow water into a stirring device according to a matching sequence for premixing and stirring to form the gelling material suspension; Before mixing and stirring the cementitious material suspension, red mud bottom flow, and waste rock aggregate, the method further includes: simultaneously inputting the red mud bottom flow and waste rock aggregate into the filling slurry preparation unit.

[0094] Ensuring that the cementitious material and overflow water are input into the mixing equipment in a matching sequence for pre-mixing and stirring is beneficial for the overflow water and cementitious material to be mixed in proportion, achieving full hydration of the cementitious material. This avoids the cementitious material being directly added to the filling slurry preparation unit with waste stone aggregate and stirring to form unhydrated dry clumps of cementitious material, thereby forming a uniform cementitious material suspension, which is beneficial for improving the quality stability of the filling slurry.

[0095] After the cementitious material and overflow water are fully mixed to form a cementitious material suspension, the red mud bottom flow and waste rock aggregate are simultaneously fed into the filling slurry preparation unit. The waste rock aggregate is used to shear and crush the red mud bottom flow, breaking up the particle agglomeration structure in the red mud bottom flow and improving the viscosity of the filling slurry, thereby improving the quality stability of the filling slurry. The waste rock aggregate, red mud bottom flow and cementitious material suspension are mixed together to complete the mixing and stirring, forming the homogeneous and stable filling slurry required for filling.

[0096] In some embodiments, after the filling slurry is transported to the area to be filled, the method further includes: the filling slurry spreading and filling within the enclosed space of the area to be filled by gravity, using the gravity of the filling slurry to spread and fill the space of the area to be filled; utilizing the continuous complementary gradation of the waste rock aggregate and red mud fine particles to offset the difference in settling velocity and segregation risk of the waste rock aggregate and red mud fine particles under their own weight, so that the waste rock aggregate and red mud fine particles are uniformly interlocked to form a dense continuous skeleton structure, fully enabling the filling slurry to fill by its own weight, and at the same time, utilizing the uniform interlocking of the waste rock aggregate and red mud fine particles to form a continuous skeleton structure, thereby improving the strength of the filling body formed by the filling slurry.

[0097] In some embodiments, the overflow water has a solids content of less than 300 ppm and contains alkaline components and sodium aluminate components; the mixing and stirring of the cementitious material suspension, red mud bottom flow and waste rock aggregate includes: the cementitious material reacts with the alkaline components and sodium aluminate components in the overflow water to promote the dissolution of the silica-alumina phase in the fine red mud particles, generating calcium-alkali-alumina silicate gel, and the calcium-alkali-alumina silicate gel encapsulates and binds the solid particles in the filling slurry, so that the homogeneous slurry as a whole hardens into a dense filling body.

[0098] The overflow water has a solids content of less than 300 ppm, which is equivalent to a near-clear water physical state. It can be directly used to prepare filling slurry with almost no additional solid load, avoiding interference from unknown suspended matter with the quality of the filling slurry. Moreover, whether it is reused and added to the blending water or used to prepare filling slurry, no additional filtration or clarification treatment is required, simplifying the process.

[0099] Furthermore, the overflow water contains sodium hydroxide and sodium aluminate components. Through the reaction between the cementing material and the alkaline components of sodium hydroxide and sodium aluminate in the overflow water, a synergistic activation mechanism is formed. In the alkaline environment of the overflow water, the dissolution of the silica-alumina phase in the fine particles of red mud is promoted, generating calcium-alkali aluminosilicate gel. The calcium-alkali aluminosilicate gel encapsulates and binds the solid particles in the filling slurry, improving the quality of the prepared filling slurry. This allows the homogeneous slurry to harden into a dense filling body, meeting the strength requirements of the filling body formed by the filling slurry. The reaction between the alkaline components and sodium aluminate in the overflow water and the cementing material is fully utilized to synergistically activate the potential cementing activity of the red mud, reducing the amount of cementing material used.

[0100] In some embodiments, the ratio of overflow water to cementitious material by weight is 1:1 to 1:1.6. When the ratio is greater than 1:1, excessive overflow water dilutes the cementitious material, weakening the bonding force between red mud particles and cementitious material particles. This also increases the risk of bleeding and segregation of the filling slurry during the curing stage, easily disrupting the homogeneity of the filling slurry and requiring longer dehydration time later, thus affecting the curing rate. Furthermore, the cementitious material particles have a large specific surface area and require sufficient free water to encapsulate them for flow. When the ratio is less than 1:1... At a water-cement ratio of 1:6, the water-cement ratio is too low, resulting in insufficient free water in the filling slurry. This leads to a dry and hard filling slurry, which is detrimental to the quality stability of the filling slurry and makes it difficult to transport through pipelines. When the filling slurry is transported to the goaf, it is also difficult to spread out by gravity, which can easily form voids or stratification in the filling body, which is detrimental to the safety of the goaf. At a mixing ratio of 1:1 to 1:1.6, the alkaline components of the overflow water are fully consumed and calcium-alkali aluminum silicate gel is generated, which improves the quality of the prepared filling slurry and avoids the formation of harmful expansion or efflorescence caused by residual free alkali in the later stage.

[0101] In some embodiments, after thickening and settling in a thickener, the upper overflow water flows into an overflow water collection tank, and the bottom of the thickener yields a red mud bottom flow with a mass concentration of 65%. Mine waste rock with a particle size of 50-200 mm is crushed by a crusher and then screened by a screening machine to produce continuously graded aggregate with a particle size ≤15 mm, which is stored in a waste rock aggregate bin. 12 parts of overflow water are pumped into the filling slurry preparation unit via an overflow water delivery pump, and 10 parts of 42.5 grade ordinary silicate cementitious material are fed into the mixer via a feeder according to the overflow water inflow sequence. 100 parts of the 65% mass concentration red mud bottom flow are delivered to the mixer, and simultaneously 35 parts of waste rock aggregate from the waste rock aggregate bin are fed into the mixer via a metering feed control component. The mixer is started and stirred for 90 seconds to obtain a uniform filling slurry. The prepared filling slurry is then pumped to the filling area via a filling delivery pipeline for filling.

[0102] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0103] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be included within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A method for co-filling red mud and waste rock, characterized in that, include: The filter cake is mixed and diluted with dilution water to obtain a red mud slurry with a mass concentration of 20-40%, which is then sent to a thickener via a transfer pump A. Anionic polyacrylamide flocculant is added to the thickener for flocculation and sedimentation; wherein the amount of anionic polyacrylamide flocculant added is 30~40g / t red mud slurry. After thickening and settling, the upper overflow water in the thickener flows into the overflow water collection tank, and the bottom of the thickener obtains red mud bottom flow with a mass concentration of 55-70%. The waste rock is crushed and screened to obtain waste rock aggregate that forms a continuous complementary gradation with the red mud bottom flow particles. 80-120 parts of red mud bottom flow with a mass concentration of 55-70% are fed into the mixer through a pipeline, and 25-50 parts of waste stone aggregate are fed into the mixer at the same time. 4-10 parts of the cementitious material are fed into the mixer via a conveyor. Start the mixer and mix for a predetermined time to obtain a filling slurry; The filling slurry is transported to the goaf area via pipeline using a filling pump for filling.

2. The method for co-filling red mud and waste rock according to claim 1, characterized in that, The step of feeding 80-120 parts of the red mud bottom flow with a mass concentration of 55-70% into the mixer through a pipeline includes: One hundred portions of the red mud bottom flow with a mass concentration of 65% were fed into the mixer through a pipeline.

3. The method for co-filling red mud and waste rock according to claim 1, characterized in that, The step of simultaneously feeding 25-50 parts of waste stone aggregate into the mixer includes: 40 portions of waste stone aggregate are simultaneously fed into the mixer.

4. The method for co-filling red mud and waste rock according to claim 1, characterized in that, The particle size of the waste stone aggregate is ≤15mm.

5. The method for co-filling red mud and waste rock according to claim 1, characterized in that, The step of feeding 4-10 parts of the cementitious material into the mixer via a conveyor includes feeding 6 parts of the cementitious material into the mixer via the conveyor.

6. The method for co-filling red mud and waste rock according to claim 1, characterized in that, Before starting the mixer, the method further includes feeding 5-20 parts of the overflow water from the top into the mixer via a delivery pump B to adjust the concentration of the slurry.

7. The method for co-filling red mud and waste rock according to claim 1, characterized in that, In the filling slurry, 65-80% of the red mud particles have a particle size of less than 75μm, and the waste stone aggregate has a particle size of 0.15-15mm.

8. A red mud and waste rock co-filling process system, used to implement the method according to any one of claims 1 to 7, characterized in that, include: A red mud thickening and settling unit includes a red mud slurry storage tank, a conveying pump A, and a thickener; the red mud slurry storage tank is provided with a dilution water addition port; the outlet A of the red mud slurry storage tank is connected to the inlet A of the thickener through the conveying pump A; Waste rock aggregate preparation unit, used to process waste rock into waste rock aggregate; A filling slurry preparation unit is used to mix and stir the input overflow water, cementing material, red mud bottom flow and waste rock aggregate to prepare filling slurry; The overflow water collection and reuse unit includes an overflow water collection tank and a transfer pump B; the inlet of the overflow water collection tank is connected to the upper overflow port of the thickener, and the outlet B of the overflow water collection tank inputs the overflow water into the filling slurry preparation unit through the transfer pump B; the outlet of the overflow water collection tank is also connected to the dilution water addition port. The filling and conveying unit is connected to the filling slurry preparation unit and is used to convey the filling slurry to the area to be filled.

9. The red mud and waste rock co-filling process system according to claim 8, characterized in that, The filling slurry preparation unit is equipped with inlets for the input of overflow water, red mud bottom flow, waste rock aggregate, and cementitious material preparation water, as well as a red mud inlet, an aggregate inlet, and a cementitious material inlet. Each inlet and water inlet of the filling slurry preparation unit is equipped with a metering and regulating component. The water inlet timing is matched with the cementitious material inlet timing. The red mud inlet timing is matched with the aggregate inlet timing.

10. The red mud and waste rock co-filling process system according to claim 8, characterized in that, The red mud slurry storage tank is equipped with a stirring device A, and the filling slurry preparation unit includes a mixer B. The stirring device A is an adjustable frequency stirring device, and the rotation speed of the stirring device A is 0~25 rpm. The mixer B is a fixed-frequency mixer, and the speed of the mixer B is 40~60 revolutions per minute.

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