Preparation method and system of green backfill material modified from phosphorus tailings

Abstract

This application provides a method and system for preparing modified green backfill material from phosphorus tailings, belonging to the field of phosphorus tailings treatment. The method includes the following steps: adding an alkaline modifier to phosphorus tailings slurry to prepare a modified slurry; injecting the modified slurry into a thickener unit and adding a flocculant to prepare a concentrated paste with a bleeding rate ≤1%; the thickener unit includes at least two paste storage thickeners; adding a curing agent and a composite water-reducing agent to the concentrated paste to prepare the modified green backfill material from phosphorus tailings; the curing agent includes active waste residue and a composite activator. This application first modifies the phosphorus tailings slurry to improve flocculation and sedimentation while initially solidifying phosphorus tailings phosphorus ...

Description

Technical Field

[0001] This invention relates to the field of phosphorus tailings treatment technology, specifically to a method and system for preparing phosphorus tailings modified green backfill material. Background Technology

[0002] Tailings-free mines are becoming the general trend in mining. The treatment of tailings in underground phosphate mines is generally to first fill the empty areas underground. After the empty areas are filled, the remaining tailings are wet-discharged to tailings ponds for storage. At present, the capacity of tailings ponds is tight. If the tailings are backfilled into open pits or subsidence pits (many mines have left large areas of open pits or subsidence pits), it can not only solve the problem of tailings pond capacity shortage, but also help restore the landform, and is increasingly becoming the mainstream of tailings treatment.

[0003] However, backfilling phosphate tailings into open pits or subsidence pits requires higher standards. The conventional method involves directly preparing the tailings into backfill slurry, which involves only adding flocculants for concentration during the slurry preparation process. However, the pH value of the phosphate tailings slurry in concentrators is 5-6, meaning it is weakly acidic. This not only affects the flocculation and sedimentation effect and results in low backfill strength, but also causes the leachate from the backfill prepared by this method to have a substandard pH value (the standard pH value is 6-9) and excessive total phosphorus and soluble fluoride content (reference standard GB8978-1996), which is detrimental to environmental protection. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a method and system for preparing phosphorus tailings modified green backfill material, which aims to solve the technical problem that the leachate of the backfill body does not meet the standards due to the direct backfilling of tailings prepared into filling slurry.

[0005] In a first aspect, embodiments of this application provide a method for preparing a green backfill material modified from phosphorus tailings, comprising the following steps:

[0006] S1. Add an alkaline modifier to the phosphorus tailings mortar to prepare a modified slurry;

[0007] S2. The modified slurry is injected into the thickener unit and a flocculant is added to prepare a concentrated paste with a water bleeding rate of ≤1%; the thickener unit includes at least two paste storage thickeners.

[0008] S3. Add a curing agent and a composite water-reducing agent to the concentrated paste to prepare a modified green backfill material for phosphorus tailings; the curing agent includes active waste residue and a composite activator.

[0009] In the technical solution of this application embodiment, an alkaline modifier is first added to the phosphorus tailings slurry before flocculation and sedimentation, thereby improving the flocculation and sedimentation effect. The alkaline modifier and flocculant work synergistically to convert soluble phosphorus and fluorine in the phosphorus tailings slurry into insoluble precipitates that are then solidified in the tailings. Next, the modified slurry is injected into a thickening unit containing at least two paste storage thickeners, and flocculant is added. By appropriately switching the operation of the paste storage thickeners, the concentration time of the modified slurry within the paste storage thickener is extended. This process yields a high-concentration concentrated paste with a bleeding rate of ≤1%. The concentrated paste is then mixed with a curing agent and a composite water-reducing agent. The curing agent and alkaline modifier work together to solidify elements such as phosphorus and phosphorus in the concentrated paste within the backfill material. The composite water-reducing agent maintains the bleeding rate of the concentrated paste while improving its fluidity, ultimately resulting in a green backfill material with compliant leachate, extremely low bleeding rate, and good fluidity. This achieves ecological restoration of open pits or subsidence pits, solving problems related to the disposal and ecological restoration of phosphorus tailings.

[0010] In some embodiments, in step S3, the active waste residue includes one or two of active furnace slag and active yellow phosphorus slag; the composite activator includes two or more of quicklime, hydrated lime, gypsum, sodium hydroxide, and water glass.

[0011] In this embodiment, by rationally setting the composition of the active waste residue and the composite activator, the F and P in the concentrated paste are further solidified in the backfill body under the synergistic effect of the active waste residue and the composite activator.

[0012] In some embodiments, in step S3, the amount of curing agent added is 5% to 15% of the total mass of the dry phosphorus tailings and the curing agent; the mass ratio of the active waste residue and the composite activator in the curing agent is (85% to 95%):(5% to 15%).

[0013] In this embodiment, by reasonably controlling the amount of curing agent added, the P, F and other elements in the phosphorus tailings are efficiently cured while avoiding excessive use of curing agent. This results in the green backfill material having a strength of more than 28 days that meets the design strength requirements (0.5~2MPa). The resulting green backfill material has high strength, ensuring the long-term effectiveness of the backfilling.

[0014] In some embodiments, step S2 specifically involves: injecting the modified slurry into different paste storage thickeners in turn, such that the concentration time of the modified slurry in the paste storage thickener is ≥12h; the paste storage thickener includes a static concentration mode, a dynamic equilibrium mode, and a pneumatic activation mode.

[0015] In this embodiment, by switching between different paste storage thickeners and switching between different functions of each paste storage thickener, the concentration time of the modified slurry in the paste storage thickener is always ensured to be ≥12h, thereby obtaining a concentrated paste with a water bleeding rate ≤1%, reducing backfilling costs and improving environmental performance.

[0016] In some embodiments, in step S1, the alkaline conditioning agent includes one or more of quicklime and hydrated lime.

[0017] In this embodiment, by rationally setting the composition of the alkaline modifier, the soluble phosphorus in the phosphorus tailings is converted into insoluble hydroxyphosphate precipitate and the fluoride ions are converted into insoluble fluoride precipitate and solidified in the backfill.

[0018] Secondly, embodiments of this application provide a system for preparing modified green backfill material from phosphorus tailings, used in the method for preparing modified green backfill material from phosphorus tailings as described in the first aspect of this application. The system includes a modified slurry preparation unit, a concentrated paste preparation unit, and a green backfill material preparation unit connected in sequence. The modified slurry preparation unit includes a mixer, a phosphorus tailings feed pipe from the beneficiation plant, and an alkaline modifier additive machine. The inlet of the mixer is connected to the outlet of the phosphorus tailings feed pipe from the beneficiation plant and the outlet of the alkaline modifier additive machine, respectively. The concentrated paste preparation unit includes a thickener unit and a flocculant additive machine. The thickener unit includes at least two paste storage thickeners, and the inlet of each paste storage thickener is connected to the outlet of the mixer and the outlet of the flocculant additive machine, respectively. The green backfill material preparation unit includes a modified slurry preparation unit, a concentrated paste preparation unit, and a green backfill material preparation unit. The green backfill material preparation unit includes a high-speed flexible mixer, a curing agent additive machine, and a composite activator additive machine. The inlet of the high-speed flexible mixer is connected to the outlet of the curing agent additive machine and the outlet of the composite activator additive machine, respectively. The alkaline modifier released by the alkaline modifier additive machine and the phosphorus tailings slurry released by the tailings feed pipe of the beneficiation plant are mixed in a mixer to prepare the modified slurry. The modified slurry released by the mixer and the flocculant released by the flocculant additive machine are mixed in a thickener unit to prepare a concentrated paste with a bleeding rate of ≤1%. The concentrated paste released by the thickener unit, the curing agent released by the curing agent additive machine, and the composite activator released by the composite activator additive machine are mixed in a high-speed flexible mixer to prepare the phosphorus tailings modified green backfill material.

[0019] In the technical solution of this application embodiment, by setting a mixer to fully modify the phosphorus tailings, not only can the effect of subsequent flocculation and sedimentation be improved, but also the soluble phosphorus and fluorine in the phosphorus tailings slurry can be converted into insoluble precipitates and solidified in the tailings. By setting a thickener unit, the use of the paste storage thickener is reasonably switched during the flocculation and sedimentation process, thereby extending the concentration time of the modified slurry in the paste storage thickener, and thus obtaining a high-concentration concentrated paste with a bleeding rate of ≤1%. By setting a green backfill material preparation unit, the concentrated paste is fully mixed and interacts with the curing agent and composite water-reducing agent, further solidifying the P, F and other elements in the concentrated paste in the backfill body, reducing the content of P and F in the leachate of the backfill body, and improving the fluidity of the concentrated paste.

[0020] In some embodiments, the paste storage thickener includes: a silo body; a pulping component disposed within the silo body for aerating and loosening the sand at the end of the slab in the silo body; and a conical silo bottom disposed on the horizontal silo bottom of the paste storage thickener, wherein the outwardly expanding end of the conical silo bottom is sealed to the inner wall of the silo body, and its contracted end abuts against the horizontal silo bottom, and the contracted end of the conical silo bottom is provided with a sand discharge port, the sand discharge port of the conical silo bottom being sealed to the sand discharge port of the horizontal silo bottom.

[0021] In this embodiment, setting the bottom of the silo as a conical bottom can improve the settling efficiency of phosphorus tailings particles; by setting a pulping component, the tailings in the middle plate of the silo can be aerated and loosened, realizing the pneumatic activation mode of the paste storage thickener.

[0022] In some embodiments, the top of the silo is provided with a stepped drainage system.

[0023] In this embodiment, by setting up a stepped drainage system, the clear water at the top of the slurry can be released to the maximum extent according to the different heights of the slurry in the chamber, which facilitates the smooth operation of the pneumatic activation mode.

[0024] In some embodiments, the discharge ports of the alkaline modifier additive machine, the flocculant additive machine, the paste storage thickener, the curing agent additive machine, and the composite activator additive machine are all equipped with a concentration meter and a flow meter.

[0025] In this embodiment, by setting up a concentration meter and a flow meter, it is convenient to detect the added concentration and flow rate of alkaline modifier, flocculant, curing agent, and composite activator, as well as the concentration of slurry released from the paste storage thickener, to ensure the accurate addition of different materials and the water bleeding rate of the concentrated paste ≤1%.

[0026] In some embodiments, the discharge port of the high-speed flexible mixer is provided with a buffer hopper.

[0027] In this embodiment, by providing a buffer hopper at the discharge port of the high-speed flexible mixer, the modified green backfill material of phosphorus tailings can be buffered and regulated, facilitating subsequent transportation.

[0028] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the phosphorus tailings modified green backfill material preparation system in the embodiments of this application;

[0031] Figure 2 This is a schematic diagram of the structure of the first paste storage and thickening machine in the embodiments of this application;

[0032] Explanation of reference numerals in the attached drawings: 100-Preparation system for modified green backfill material from phosphorus tailings; 1-Modified slurry preparation unit; 2-Concentrated paste preparation unit; 3-Green backfill material preparation unit; 4-Buffer hopper; 5-Centrifugal filling pump; 6-Backfill pit; 7-Return water pump; 11-Mixer; 12-Phosphorus tailings feed pipe from the beneficiation plant; 13-Alkaline modifier additive; 21-Flocculant additive; 22-First paste storage thickener; 23-Second paste storage thickener; 31-High-speed flexible mixer; 32-Curing agent additive; 33-Composite activator additive; 221-Self-body; 222-Conical silo bottom; 223-Horizontal silo bottom; 224-Sand discharge port; 225-Step drainage system. Detailed Implementation

[0033] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0035] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0038] In the description of the embodiments of this application, the technical terms "top", "bottom", "inner" and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0039] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0040] Tailings-free mining is becoming the general trend in mining operations, and backfilling phosphorus tailings into open pits or subsidence pits is increasingly becoming the mainstream tailings treatment method. The conventional method for preparing backfill mainly involves preparing tailings into backfill slurry for direct backfilling. However, the pH value of the leachate from the backfill prepared by this method does not meet the standard (the standard pH value is 6-9), and the total phosphorus and soluble fluoride content in the leachate exceeds the standard (reference standard is GB8978-1996), which is detrimental to environmental protection.

[0041] To address the technical problem of substandard leachate from backfill materials caused by directly backfilling tailings slurry, this application provides a method and system for preparing modified green backfill material from phosphorus tailings. The method involves first adding an alkaline modifier to the phosphorus tailings slurry before flocculation and sedimentation to improve the flocculation and sedimentation effect. The alkaline modifier and flocculant synergistically convert soluble phosphorus and fluorine in the phosphorus tailings slurry into insoluble precipitates that are then solidified within the tailings. Next, the modified slurry is injected into a thickening unit containing at least two paste storage thickeners, and flocculants are added. The method involves appropriately switching between the paste storage thickeners. The process of using this method extends the concentration time of the modified slurry in the paste storage thickener, thereby obtaining a high-concentration concentrated paste with a bleeding rate of ≤1%. Finally, the concentrated paste is mixed with a curing agent and a composite water-reducing agent. The curing agent and alkaline modifier synergistically solidify elements such as phosphorus and phosphorus in the concentrated paste within the backfill. The composite water-reducing agent improves the fluidity of the concentrated paste while maintaining its bleeding rate, ultimately resulting in a green backfill material with compliant leachate, extremely low bleeding rate, and good fluidity. This achieves ecological restoration of open pits or subsidence pits, solving the problems of phosphorus tailings disposal and ecological restoration. This application's backfilling and ecological restoration scheme for open pits or subsidence pits not only disposes of tailings and solves the tailings disposal problem but also restores the environment, achieving two goals at once.

[0042] Phosphate ore beneficiation employs flotation, resulting in tailings that are predominantly extremely fine (generally defined as tailings containing over 50% -20μm particles). When these extremely fine tailings are concentrated in a thickener, the tailings particles mix with flocculants, and the flocculant molecules encapsulate the tailings particles and a large number of water molecules, forming flocs. The encapsulated water is difficult to release quickly, resulting in a relatively loose slurry within the thickener, reducing the concentration of the slurry discharged from the thickener. Furthermore, the vertical section sidewall height of a conventional deep cone thickener is typically 10m. To avoid rake damage, the mud layer formed by the tailings flocs in the thickener generally cannot exceed 7m in height. The presence of a rake at the bottom of the thickener further restricts the space and time for tailings storage within the thickener, further impacting the concentration effect. Moreover, conventional thickeners have a low tailings processing capacity (0.3~0.5t / m³). 2 The thickener has low efficiency, is difficult to flocculate and settle, consumes a lot of flocculant, and is prone to turbidity. Ultimately, the slurry discharged from the thickener has a low concentration and cannot form a paste. It also increases backfilling costs and environmental risks.

[0043] Furthermore, backfilling open pits or subsidence pits is only for disposing of tailings and restoring the ecological environment, and cannot bring economic benefits to enterprises. If the cost of backfilling and ecological restoration is too high, the economic benefits of enterprises will be damaged, and in the long run, enterprises will find it difficult to bear. Generally, the cost of constructing and operating tailings dams is 40 yuan / ton dry basis when allocated to tailings. Therefore, enterprises are committed to controlling the direct cost of backfilling open pits or subsidence pits to within 40 yuan / ton, which is comparable to the cost of constructing a tailings dam.

[0044] In a first aspect, embodiments of this application provide a method for preparing a green backfill material modified from phosphorus tailings, comprising the following steps:

[0045] S1. Add an alkaline modifier to the phosphorus tailings slurry to prepare a modified slurry. Specifically, since the pH value of the phosphorus tailings slurry in the concentrator is 5-6, which is acidic, and acidity is not conducive to the concentration, sedimentation, coagulation, and ecological restoration of tailings, an alkaline modifier is used to modify the phosphorus tailings before concentration and sedimentation. On the one hand, this can improve the flocculation and sedimentation effect, and on the other hand, it can convert soluble phosphorus and fluorine in the phosphorus tailings slurry into insoluble precipitates and solidify them in the tailings.

[0046] S2. The modified slurry is injected into the thickener unit, and a flocculant is added to prepare a concentrated paste with a bleeding rate of ≤1%. The thickener unit includes at least two paste storage thickeners. Specifically, by setting up at least two paste storage thickeners and by reasonably switching the usage process of the paste storage thickeners, the concentration time of the modified slurry in the paste storage thickener is extended, so that the concentration of the modified slurry is ≥5% higher than that of the conventional thickener, and the concentration of the resulting concentrated paste fluctuates within ±2%, thereby obtaining a high-concentration concentrated paste with a bleeding rate of ≤1%, i.e., obtaining an ultimate paste.

[0047] S3. Add a curing agent and a composite water-reducing agent to the concentrated paste to prepare a modified green backfill material for phosphorus tailings. The curing agent includes active waste residue and a composite activator. Specifically, the curing agent is a novel cementitious material for phosphorus tailings, using potentially active (containing Ca, Al, SiO2, etc.) slag and yellow phosphorus slag as the main bulk materials. A composite activator is used for activation, further solidifying P, F, and other elements in the concentrated paste. The main components of the composite water-reducing agent are polycarboxylic acid, modified sodium lignosulfonate, air-entraining agents, and retarders. The polycarboxylic acid accounts for 30%–40% of the mass, and the modified sodium lignosulfonate accounts for 30%–35%. The air-entraining agent includes one or more of sodium dodecyl sulfate and modified rosin (such as rosin triethanolamine salt), whose main function is to introduce uniform and stable microbubbles, improving the workability and durability of the paste slurry. The addition amount of the composite water-reducing agent is generally 300–700 g / t dry basis. Composite water-reducing agents can improve the fluidity of concentrated paste while maintaining its water bleeding rate, making it easier to backfill into open pits or subsidence pits.

[0048] In the technical solution of this application embodiment, before flocculation and sedimentation, an alkaline modifier is added to the phosphorus tailings slurry to modify the phosphorus tailings. This improves the subsequent flocculation and sedimentation effect and, in synergy with the flocculant, converts soluble phosphorus and fluorine (phosphorus tailings slurry contains virtually no arsenic) into insoluble precipitates that are then solidified in the tailings. Next, the modified slurry is injected into the thickener unit, and a flocculant is added. By setting the thickener unit to at least two paste storage thickeners, the use of the paste storage thickeners is reasonably switched during the flocculation and sedimentation process, extending the time for the modified slurry to reach the paste storage thickener stage. The concentration time within the machine is adjusted to obtain a high-concentration concentrated paste (i.e., an ultra-high-quality paste) with a bleeding rate of ≤1%. Finally, the concentrated paste is mixed with a curing agent and a composite water-reducing agent. The curing agent further solidifies elements such as phosphorus (P) and phosphorus (F) in the concentrated paste within the backfill material, reducing the P and F content in the leachate and preventing secondary pollution to the surrounding environment, thus meeting environmental standards and achieving ecological restoration. The composite water-reducing agent maintains the bleeding rate of the concentrated paste while improving its fluidity, making it easier to backfill into open pits or subsidence pits. The final result is a green backfill material with leached water meeting standards (reference standard GB 8978-1996 "Integrated Wastewater Discharge Standard"), extremely low bleeding rate, and good fluidity, achieving ecological restoration of open pits or subsidence pits. Furthermore, the alkaline modifier, curing agent, and composite water-reducing agent used in this application have low costs, keeping the backfill cost below 35 yuan / ton dry basis.

[0049] Furthermore, in some embodiments, in step S3, the active waste residue includes one or two of active furnace slag and active yellow phosphorus slag; the composite activator includes two or more of quicklime, hydrated lime, gypsum, sodium hydroxide, water glass, etc.

[0050] In the technical solution of this application embodiment, by reasonably setting the composition of active waste residue and composite activator, firstly, F, P and other substances in the concentrated paste react with the composite activator to generate fluoride precipitates, hydroxyphosphate precipitates, etc. Then, the fluoride precipitates and hydroxyphosphate precipitates react with the active waste residue to finally generate calcium aluminosilicate gel, that is, the F and P in the concentrated paste are further solidified in the backfill.

[0051] Furthermore, in some embodiments, in step S3, the amount of curing agent added is 5% to 15% of the total mass of the dry phosphorus tailings and the curing agent; the mass ratio of active waste residue and composite activator in the curing agent is (85% to 95%):(5% to 15%).

[0052] In the technical solution of this application embodiment, by reasonably controlling the amount of curing agent added, the P, F and other elements in the phosphorus tailings are efficiently cured while avoiding excessive use of curing agent, thereby controlling the final setting time to within 24 hours. At the same time, the strength of the obtained green backfill material reaches the design strength requirement (0.5~2MPa) or higher after 28 days. The obtained green backfill material has high strength, ensuring the long-term effectiveness of the backfilling effect.

[0053] Further, in some embodiments, step S2 specifically involves: injecting the modified slurry into different paste storage thickeners in turn, such that the concentration time of the modified slurry in the paste storage thickener is ≥12h; the paste storage thickener includes a static concentration mode, a dynamic equilibrium mode, and a pneumatic activation mode. Specifically, in conventional thickening processes, the maximum concentration time of tailings in the thickener is 8h. The tailings slurry in the thickener consists of a clear water layer, a settling layer, a compression layer, and a compacted layer in the vertical direction from top to bottom. The concentration of the tailings slurry in the compacted layer is positively correlated with the concentration time within a certain range; the longer the time, the higher the concentration of the tailings slurry. When the concentration time of the modified slurry in the paste storage thickener is ≥12h, the concentration of the tailings slurry in the compacted layer of the paste storage thickener can be significantly increased, resulting in a concentrated paste with a bleeding rate ≤1%.

[0054] In the technical solution of this application embodiment, each paste storage thickener has three modes: static concentration mode, dynamic balance mode, and pneumatic activation mode. By switching between different paste storage thickeners and switching between different functions of each paste storage thickener, the concentration time of the modified slurry in the paste storage thickener is always ensured to be ≥12h, ensuring that the phosphorus tailings have sufficient concentration time, thereby obtaining a concentrated paste with a bleeding rate of ≤1%, reducing backfilling costs and improving environmental performance.

[0055] Furthermore, in some embodiments, in step S1, the alkaline modifier includes one or more of quicklime, hydrated lime, etc. Specifically, one or more of quicklime, hydrated lime, etc., are prepared into a slurry of a certain concentration to obtain the alkaline modifier. The amount of alkaline modifier solution added is 1~2 m³ / h, which is equivalent to an alkaline modifier addition amount of 1~2 kg / t dry tailings.

[0056] In the technical solution of this application embodiment, by reasonably setting the composition of the alkaline modifier, the soluble phosphorus in the tailings reacts with calcium oxide or calcium hydroxide to form insoluble hydroxyphosphate precipitates that are solidified in the modified slurry. Similarly, fluoride ions react with calcium oxide or calcium hydroxide to form insoluble fluoride precipitates that are solidified in the modified slurry. By reasonably setting the amount of alkaline modifier added, the initial solidification of soluble phosphorus and fluoride in the tailings is ensured while avoiding excessive use of alkaline modifier that could affect the strength and pH value of the final backfill.

[0057] Please refer to Figure 1Secondly, embodiments of this application provide a system 100 for preparing modified green backfill material from phosphorus tailings, used in the aforementioned method for preparing modified green backfill material from phosphorus tailings. The system includes: a modified slurry preparation unit 1, a concentrated paste preparation unit 2, and a green backfill material preparation unit 3 connected in sequence. The modified slurry preparation unit 1 includes a mixer 11, a phosphorus tailings feed pipe 12 from the beneficiation plant, and an alkaline modifier additive machine 13. The inlet of the mixer 11 is connected to the outlet of the phosphorus tailings feed pipe 12 from the beneficiation plant and the outlet of the alkaline modifier additive machine 13, respectively. The concentrated paste preparation unit 2 includes a thickener unit and... The flocculant additive unit 21 and the thickening unit include at least two paste storage thickeners, preferably two paste storage thickeners, namely a first paste storage thickener 22 and a second paste storage thickener 23. The inlet of each paste storage thickener is connected to the outlet of the mixer 11 and the outlet of the flocculant additive unit 21, respectively. The green backfill material preparation unit 3 includes a high-speed flexible mixer 31, a curing agent additive unit 32, and a composite activator additive unit 33. The inlet of the high-speed flexible mixer 31 is connected to the outlet of the curing agent additive unit 32 and the outlet of the composite activator additive unit 33, respectively. Specifically, the mixer 11, the tailings feed pipe 12 of the beneficiation plant, the alkaline modifier additive unit 13, the flocculant additive unit 21, the paste storage thickener, the high-speed flexible mixer 31, the curing agent additive unit 32, and the composite activator additive unit 33 are all equipped with pumping devices at their outlets. A variable frequency centrifugal feed pump is used to pump the alkaline modifier and the phosphate tailings slurry from the beneficiation plant to the mixer 11, so that the phosphate tailings slurry and the alkaline modifier are fully mixed in the mixer 11 to prepare a modified slurry. Then, the modified slurry discharged from the mixer 11 and the flocculant discharged from the flocculant additive machine 21 react in the thickener unit, so that the modified slurry flocculates and settles to prepare a concentrated paste with a bleeding rate ≤1%. The concentrated paste discharged from the thickener unit, the curing agent discharged from the curing agent additive machine 32, and the composite activator discharged from the composite activator additive machine 33 are activated and stirred in a high-speed flexible mixer 31 (using a speed of more than 200 r / min and a stirring time of not less than 3 min) to prepare a phosphate tailings modified green backfill material. The specific preparation process of the concentrated paste is as follows:

[0058] In the technical solution of this application embodiment, by setting a mixer 11, the phosphorus tailings slurry from the beneficiation plant and the alkaline modifier are fully mixed to modify the phosphorus tailings. This not only improves the subsequent flocculation and sedimentation effect, but also converts soluble phosphorus and fluorine in the phosphorus tailings slurry into insoluble precipitates that are solidified in the tailings. By setting a thickener unit, which includes at least two paste storage thickeners, the use of the paste storage thickeners is reasonably switched during the flocculation and sedimentation process, thereby extending the concentration time of the modified slurry in the paste storage thickener, and thus obtaining a high-concentration concentrated paste (i.e., ultimate paste) with a water bleeding rate of ≤1%. By setting up a high-speed flexible mixer 31, a curing agent additive 32, and a composite activator additive 33, the concentrated paste is fully mixed and interacts with the curing agent and composite water-reducing agent, further solidifying elements such as P and F in the concentrated paste into the backfill, reducing the content of P and F in the leachate of the backfill, and improving the fluidity of the concentrated paste, making it easier to backfill the backfill into open pits or subsidence pits.

[0059] Furthermore, in some embodiments, the first paste storage thickener 22 and the second paste storage thickener 23 have the same structure; the first paste storage thickener 22 will be used as an example for explanation. Figure 2 As shown, the first paste storage thickener 22 includes: a silo body 221; a pulping component disposed within the silo body 221 for aerating and loosening the sand at the end of the plate in the silo body 221; and a conical silo bottom 222 disposed on a horizontal silo bottom 223 of the first paste storage thickener 22. The outwardly expanding end of the conical silo bottom 222 is sealed to the inner wall of the silo body 221, and its contracted end abuts against the horizontal silo bottom 223. The contracted end of the conical silo bottom 222 is provided with a sand discharge port 224, which is sealed to the sand discharge port 224 of the horizontal silo bottom 223. Other detailed structural features of the first paste storage thickener 22 and the second paste storage thickener 23 can be found in patent application number CN202322371733.3, and will not be repeated here.

[0060] In the technical solution of this application embodiment, the bottom of the silo 221 is set as a conical silo bottom 222, which can improve the settling efficiency of the phosphorus tailings particles. The sand discharge port 224 of the silo 221 is set at the concave end of the conical silo bottom 222, and the tailings in the silo 221 can quickly slide into the sand discharge port 224 under the guidance of the conical surface of the conical silo bottom. By setting a slurry making component, the tailings in the middle plate of the silo 221 can be aerated and loosened, realizing the pneumatic activation mode of the first paste storage thickener 22. Compared with the conventional deep cone thickener, the first paste storage thickener 22 does not have a stirring mechanism, which reduces energy consumption.

[0061] Furthermore, in some embodiments, such as Figure 1 and Figure 2As shown, the top of the silo 221 is provided with a stepped drainage system 225, which includes several drain valves at different horizontal heights.

[0062] In the technical solution of this application embodiment, by setting a stepped drainage system 225 at different horizontal heights on the top of the silo 221, the clear water at the top of the slurry can be released to the maximum extent according to the different heights of the slurry in the silo 221, which facilitates the smooth operation of the pneumatic activation mode.

[0063] Furthermore, in some embodiments, the outlet ends of the alkaline modifier additive machine 13, the flocculant additive machine 21, the paste storage thickener, the curing agent additive machine 32, and the composite activator additive machine 33 are all equipped with concentration meters and flow meters.

[0064] In the technical solution of this application embodiment, by installing concentration meters and flow meters at the outlets of the alkaline modifier additive machine 13, flocculant additive machine 21, curing agent additive machine 32, and composite activator additive machine 33, it is convenient to detect the added concentration and flow rate of alkaline modifier, flocculant, curing agent, and composite activator. By installing a concentration meter at the outlet of the paste storage thickener, it is convenient to monitor the concentration of the slurry released from the paste storage thickener in real time, ensuring that the water bleeding rate of the concentrated paste is ≤1%. When the concentration of the slurry released from the paste storage thickener is lower than the preset value, the sand discharge port 224 of the silo 221 is closed, allowing the slurry in the silo 221 to further flocculate and settle until the sand discharge requirement is met.

[0065] The specific process of flocculation and sedimentation of modified slurry is as follows: (1) The modified slurry discharged from mixer 11 first enters the first paste storage thickener 22 until the first paste storage thickener 22 reaches the preset feed amount (generally refers to reaching the maximum feed amount, i.e., full state, feed time ≥ 12h), realizing the static concentration mode; (2) Stop feeding into the first paste storage thickener 22 and switch to feeding into the second paste storage thickener 23 until the second paste storage thickener 23 reaches the preset feed amount (feed time ≥ 12h), realizing the static concentration mode; (3) At this time, the concentration time of the first paste storage thickener 22 meets ≥ 12h, and the first paste storage thickener 22 enters the dynamic balance mode. When the concentration meter at the discharge port of the first paste storage thickener 22 detects that the concentration of the discharged concentrated paste is less than the preset value (i.e., the water seepage of the concentrated paste), the concentration of the concentrated paste is less than the preset value. (4) The second paste storage thickener 23 enters dynamic balancing mode (since the feeding time is ≥12h, and the first paste storage thickener 22 also consumes a certain amount of time in dynamic balancing mode, the concentration time of the second paste storage thickener 23 in dynamic balancing mode can meet ≥12h). When the concentration meter at the discharge port of the second paste storage thickener 23 detects that the concentration of the discharged concentrated paste is less than the preset value (i.e., the water bleeding rate of the concentrated paste is >1%), the sand discharge stops; (5) Then switch to the first paste storage thickener 22 in dynamic balancing mode; (6) Before the first paste storage thickener 22 or the second paste storage thickener 23 discharges sand, the excess water of the supernatant is discharged through the stepped drainage system 225, and then the pulping component is started to realize pulping and sand discharge, that is, to realize the pneumatic activation mode. When the first paste storage thickener 22 is in dynamic balancing mode, the second paste storage thickener 23 can be in pneumatic activation mode. That is, by continuously switching the working mode between the first paste storage thickener 22 or the second paste storage thickener 23, while ensuring that the modified slurry continuously enters the thickener unit, the water bleeding rate of the concentrated paste discharged from the sand outlet is ≤1%.

[0066] Furthermore, in some embodiments, the discharge port of the high-speed flexible mixer 31 is equipped with a buffer hopper 4. Specifically, after the phosphorus tailings modified green backfill material is prepared, it first enters the buffer hopper 4 for buffering and adjustment, and then is pumped by the centrifugal filling pump 5 to the nearest backfill pit 6 (i.e., an open pit or a subsidence pit). The centrifugal filling pump 5 is an improved and optimized centrifugal slurry pump, with a larger and stronger impeller and a higher motor power to adapt to the conveying of phosphorus tailings modified green backfill material. During the conveying process of the phosphorus tailings modified green backfill material, the centrifugal filling pump 5 shears the phosphorus tailings modified green backfill material, which can re-stir the material, further improve its fluidity, and reduce the conveying resistance. The conveying distance of the centrifugal filling pump 5 is required to be less than about 1 km, with an elevation difference of 0 m or less. During the backfilling of backfill pit 6, the principle of "zoning and layering" was adopted. That is, the entire area of ​​backfill pit 6 was divided into small units in each layer, and the area of ​​each unit was controlled at 70×70m based on the site conditions. 2 Within the layer, the height of each layer is ≤1.5m. Filter pipes are laid at the bottom and drainage ditches are made around the perimeter. The very small amount of filter water from the phosphorus tailings modified green backfill material is collected in the temporary collection pit of each layer and then pumped to a dedicated water treatment plant by the return water pump 7 to ensure that the filter water is not discharged outside.

[0067] In the technical solution of this application embodiment, by providing a buffer hopper 4 at the discharge port end of the high-speed flexible mixer 31, the modified green backfill material of phosphorus tailings can be buffered and adjusted, which facilitates subsequent transportation.

[0068] The present invention will now be described in detail through specific embodiments.

[0069] Example 1

[0070] A method for preparing a green backfill material modified from phosphorus tailings includes the following steps:

[0071] S1. Quicklime is prepared into a slurry with a mass concentration of 13%, and an alkaline modifier is obtained. The alkaline modifier is added to the phosphorus tailings slurry, and the amount of alkaline modifier solution added is 1.8m. 3 / h, equivalent to adding 1.8 kg of quicklime per t of dry tailings, to prepare modified slurry. The resulting modified slurry has a pH of 7-8 and a mass concentration of 30%.

[0072] S2. Inject the modified slurry into the thickener unit and add anionic polyacrylamide flocculant. By reasonably switching the use of the paste storage thickener, the modified slurry is injected into different paste storage thickeners in turn to extend the concentration time of the modified slurry in the paste storage thickener, so that the concentration time of the modified slurry in the paste storage thickener is ≥12h, so that the sand discharge concentration of the thickener is at its extreme paste state, and a concentrated paste with a water bleeding rate of 0.8% is obtained.

[0073] S3. Add a curing agent and a composite water-reducing agent to the concentrated paste to prepare a phosphorus tailings modified green backfill material; wherein, the curing agent includes active waste residue and a composite activator. Specifically, the curing agent is a potentially active slag (such as a by-product generated during high-temperature smelting of ore in the metallurgical industry, whose main components are inorganic oxides such as silicates and aluminates, which have potential cementing activity) and a composite activator (prepared by mixing quicklime and gypsum in a mass ratio of 1:1) in a mass ratio of 90%:10%. The amount of curing agent added is phosphorus... The total mass of tailings dry basis and curing agent (i.e., total dry basis mass) is 10%. The main components of the composite water-reducing agent are polycarboxylic acid, modified sodium lignosulfonate, air-entraining agent, and retarder, etc. Among them, the mass proportion of polycarboxylic acid is 35%, the mass proportion of modified sodium lignosulfonate is 32%, the air-entraining agent is composed of rosin, and its mass proportion is 0.01%~0.1%. The retarder is mainly composed of sodium gluconate, and its mass proportion is 0.3%~2%. The remainder is water and stabilizer. The addition amount of the composite water-reducing agent is 500g / t dry basis.

[0074] Example 2 and Comparative Example 1

[0075] A method for preparing a green backfill material modified from phosphorus tailings is different from that in Example 1, the water bleeding rate of the concentrated paste obtained in step S2 is different. The other steps are roughly the same as in Example 1 and will not be repeated here.

[0076] The performance of the phosphorus tailings modified green backfill materials prepared in Examples 1-2 and Comparative Example 1 was tested, and the results are shown in Table 1.

[0077] Strength testing was conducted using a TYE-300 pressure testing machine;

[0078] Leachate was prepared using either the "Solid Waste Leaching Toxicity Leaching Method - Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007) or the "Horizontal Oscillation Method" (HJ 557-2010) (soaking time is usually 18±2 hours). The total phosphorus content of the leachate was then determined according to the "Determination of Total Phosphorus in Water - Ammonium Molybdate Spectrophotometric Method" (GB 11893-89), and the fluoride content was determined according to the "Determination of Fluoride in Water - Ion Selected Electrode Method" (GB 7484-87). The pH value was measured using a pH meter.

[0079] Table 1. Performance of the phosphorus tailings modified green backfill material in Examples 1-2 and Comparative Example 1

[0080]

[0081] As shown in Table 1, when the water bleeding rate of the concentrated paste is ≤1%, the 28-day strength of the obtained phosphorus tailings modified green backfill material is greater than or equal to 1.3 MPa, the pH value of the leachate is between 8 and 9, the P content (referring to total phosphorus content) and F content are relatively low, and the leachate meets the discharge standards specified in GB8978-1996 (in the discharge standards, the F content is ≤10 mg / L and the total P content is ≤0.5 mg / L). When the bleeding rate of the concentrated paste was 1.2%, the 28-day strength of the resulting phosphorus tailings modified green backfill material was low, and the pH value of the leachate exceeded 9, while the P and F contents also increased. This may be because as the bleeding rate of the concentrated paste increases, the mass concentration of the concentrated paste gradually decreases (the mass concentration is about 67% when the bleeding rate is 0.8%; about 65% when the bleeding rate is 1%; and about 63% when the bleeding rate is 1.2%). When the mass concentration of the concentrated paste decreases, its interaction with the curing agent and composite water-reducing agent results in lower strength of the resulting phosphorus tailings modified green backfill material, and the curing effect of the curing agent on P and F will also weaken, thus affecting the composition and content of the leachate.

[0082] Examples 3-4 and Comparative Examples 2-3

[0083] A method for preparing a phosphorus tailings modified green backfill material differs from Example 1 in that the mass ratio of potentially active slag and composite activator in the curing agent is different in step S3. The rest is roughly the same as in Example 1 and will not be repeated here.

[0084] The performance of the phosphorus tailings modified green backfill materials prepared in Examples 3-4 and Comparative Examples 2-3 was tested, and the results are shown in Table 2.

[0085] Table 2 shows the performance of the phosphorus tailings modified green backfill materials in Examples 3-4 and Comparative Examples 2-3.

[0086]

[0087] As shown in Table 2, within a certain range, with the continuous increase of the mass ratio of potentially active slag and composite activator in the curing agent, the 28-day strength and pH of the leachate of the obtained phosphorus tailings modified green backfill material gradually decrease, while the P and F contents of the leachate show an increasing trend. The overall performance of the obtained phosphorus tailings modified green backfill material is better. This may be because the change in the mass ratio of potentially active slag and composite activator in the curing agent affects the reaction between F, P, etc. in the concentrated paste and the composite activator and slag to a certain extent, thereby affecting the curing effect of the curing agent on P and F in the phosphorus tailings, and also affecting the structure and strength of the obtained phosphorus tailings modified green backfill material.

[0088] When the content of potentially active slag in the curing agent is too high, the content of composite activator is too low, which affects the full reaction between F, P and other substances in the concentrated paste and the curing agent, thus affecting the coating effect of the curing agent on F and P, i.e. the curing effect. At the same time, it affects the structure of the phosphorus tailings modified green backfill material, i.e. its strength.

[0089] When the content of potentially active slag in the curing agent is too low, the content of composite activator is too high. Although F and P in the concentrated paste can react fully with quicklime to form precipitate, the slag content is relatively low at this time, so it cannot interact well with the precipitate, thus affecting the coating effect of the curing agent on F and P. In addition, the excessive amount of composite activator makes the pH of the leachate too high, exceeding the standard, and increases the cost. This shows that the ratio of potentially active slag to composite activator in the curing agent needs to be within a reasonable range to achieve a good curing effect.

[0090] Examples 5-6 and Comparative Examples 4-5

[0091] A method for preparing a green backfill material modified from phosphorus tailings is disclosed. The difference between this method and Example 1 is that the amount of curing agent added in step S3 is different. The other steps are roughly the same as in Example 1 and will not be repeated here.

[0092] The performance of the phosphorus tailings modified green backfill materials prepared in Examples 5-6 and Comparative Examples 4-5 was tested, and the results are shown in Table 3.

[0093] Table 3 shows the performance of the phosphorus tailings modified green backfill materials in Examples 5-6 and Comparative Examples 4-5.

[0094]

[0095] Table 3 shows that with the increase of the amount of curing agent added, the 28-day strength of the obtained phosphorus tailings modified green backfill material gradually increases, while the P and F contents of the leachate gradually decrease, and the pH value gradually increases. When the amount of curing agent added is too large, although the strength of the obtained phosphorus tailings modified green backfill material is high, the cost increases significantly, and the pH value of the leachate exceeds the standard. When the amount of curing agent added is too small, the curing effect is poor, resulting in a significantly lower 28-day strength of the phosphorus tailings modified green backfill material, while the P and F contents of the leachate are relatively high.

[0096] Comparative Example 6

[0097] A method for preparing modified green backfill material from phosphorus tailings is disclosed. Compared with Example 1, the difference is that in step S1, the phosphorus tailings slurry is not modified, that is, no alkaline modifier is added, to ensure that the concentration of the phosphorus tailings slurry is the same as that of the modified slurry in Example 1. The rest is roughly the same as in Example 1, and will not be repeated here.

[0098] Comparative Example 7

[0099] A method for preparing a green backfill material modified with phosphorus tailings is different from that in Example 1 in that no curing agent is added in step S3. The rest is roughly the same as in Example 1 and will not be described again here.

[0100] Comparative Example 8

[0101] A method for preparing a modified green backfill material from phosphorus tailings is different from that in Example 1 in that no composite water-reducing agent is added in step S3. The rest is roughly the same as in Example 1 and will not be described again here.

[0102] Comparative Example 9

[0103] A method for preparing a modified green backfill material from phosphorus tailings differs from Example 1 in that the phosphorus tailings slurry is directly prepared into a backfill slurry, i.e., only a flocculant is added for concentration during the preparation of the backfill material.

[0104] The performance of the phosphorus tailings modified green backfill materials prepared in proportions 6 to 9 was tested, and the results are shown in Table 4.

[0105] Table 4 shows the performance of the green backfill materials modified from phosphorus tailings in Comparative Examples 6-9.

[0106]

[0107] As can be seen from the data in Comparative Example 6 and Example 1 in Table 4, when the phosphorus tailings slurry is not modified in step S1, the performance of the resulting phosphorus tailings modified green backfill material is significantly worse. This may be because when the phosphorus tailings slurry is not modified, it is weakly acidic, which affects the flocculation and sedimentation effect. At the same time, it affects the water bleeding rate of the resulting concentrated paste. Furthermore, the composition of the resulting concentrated paste is different from that in Example 1, which affects the interaction between the curing agent and the concentrated paste, ultimately affecting the structure and performance of the phosphorus tailings modified green backfill material. Also, since the phosphorus tailings slurry is not modified in step S1, it directly affects the pH value of the leachate.

[0108] The data from Comparative Example 7 and Example 1 show that when no curing agent is added in step S3, the performance of the resulting phosphorus tailings modified green backfill material is significantly worse. This may be because, without the addition of a curing agent, the soluble phosphorus and fluorine in the phosphorus tailings slurry are converted into insoluble precipitates and solidified in the tailings by the alkaline modifier alone, which cannot effectively solidify P and F. Furthermore, without a curing agent, the phosphorus tailings and the curing agent cannot be combined, which seriously affects the strength of the phosphorus tailings modified green backfill material.

[0109] The data from Comparative Example 8 and Example 1 show that when no composite water-reducing agent is added in step S3, the fluidity of the obtained phosphorus tailings modified green backfill material is significantly poor, making it difficult to achieve smooth backfilling of the phosphorus tailings modified green backfill material.

[0110] The data from Comparative Example 9 and Example 1 show that when phosphorus tailings slurry is directly prepared into backfill slurry, the performance of the resulting backfill material is significantly worse, indicating that the method of this application can obtain high-performance backfill material.

[0111] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a green backfill material modified from phosphorus tailings, characterized in that, Includes the following steps: S1. Add an alkaline modifier to the phosphorus tailings mortar to prepare a modified slurry; S2. The modified slurry is injected into a thickener unit, and flocculant is added to prepare a concentrated paste with a bleeding rate ≤1%. The thickener unit includes a first paste storage thickener and a second paste storage thickener. Both the first and second paste storage thickeners include a stepped drainage system and a slurry-making component. Both the first and second paste storage thickeners include a static concentration mode, a dynamic equilibrium mode, and a pneumatic activation mode. The specific process of flocculation and sedimentation of the modified slurry is as follows: the modified slurry first enters the first paste storage thickener until the first paste storage thickener reaches the preset feed rate, and the feeding time is ≥12 hours to achieve the static concentration mode; feeding into the first paste storage thickener is stopped, and feeding into the second paste storage thickener is switched until the second paste storage thickener reaches the preset feed rate. The feed time is ≥12h to achieve static concentration mode; then the first paste storage thickener enters dynamic balancing mode. When the concentration of the concentrated paste discharged from the discharge port of the first paste storage thickener is less than the preset value, sand discharge stops; then the second paste storage thickener enters dynamic balancing mode. When the concentration of the concentrated paste discharged from the discharge port of the second paste storage thickener is less than the preset value, sand discharge stops; then switch to the first paste storage thickener for dynamic balancing mode; before the first or second paste storage thickener discharges sand, excess water in the supernatant is discharged through the stepped drainage system, and then the pulping component is started to achieve pulping and sand discharge, thereby achieving pneumatic activation mode; the pulping component is used to aerate and loosen the sand at the end of the middle plate of the first and second paste storage thickeners. S3. Add a curing agent and a composite water-reducing agent to the concentrated paste to prepare a phosphorus tailings modified green backfill material; the curing agent includes active waste residue and a composite activator; the active waste residue includes one or two of active slag and active yellow phosphorus slag; the composite activator includes two or more of quicklime, hydrated lime, gypsum, sodium hydroxide, and water glass.

2. The method for preparing phosphorus tailings modified green backfill material according to claim 1, characterized in that, In step S3, the amount of curing agent added is 5% to 15% of the total mass of dry phosphorus tailings and curing agent; the mass ratio of the active waste residue and the composite activator in the curing agent is (85% to 95%):(5% to 15%).

3. The method for preparing phosphorus tailings modified green backfill material according to claim 1, characterized in that, In step S1, the alkaline conditioning agent includes one or more of quicklime and slaked lime.

4. A system for preparing phosphorus tailings modified green backfill material, used to implement the method for preparing phosphorus tailings modified green backfill material according to any one of claims 1-3, characterized in that, The phosphorus tailings modified green backfill material preparation system includes a modified slurry preparation unit, a concentrated paste preparation unit, and a green backfill material preparation unit connected in sequence. The modified slurry preparation unit includes a mixer, a feed pipe for phosphorus tailings from the concentrator, and an alkaline modifier additive machine. The feed inlet of the mixer is connected to the discharge outlet of the feed pipe for phosphorus tailings from the concentrator and the discharge outlet of the alkaline modifier additive machine, respectively. The concentrated paste preparation unit includes a thickener unit and a flocculant additive unit. The thickener unit includes a first paste storage thickener and a second paste storage thickener. The inlets of the first paste storage thickener and the second paste storage thickener are respectively connected to the outlet of the mixer and the outlet of the flocculant additive unit. The green backfill material preparation unit includes a high-speed flexible mixer, a curing agent additive machine, and a composite activator additive machine. The inlet of the high-speed flexible mixer is connected to the outlet of the curing agent additive machine and the outlet of the composite activator additive machine, respectively. The alkaline modifier dispensed from the alkaline modifier additive machine and the phosphorus tailings slurry dispensed from the tailings feed pipe of the beneficiation plant are used to prepare the modified slurry in the mixer; the modified slurry dispensed from the mixer and the flocculant dispensed from the flocculant additive machine are used to prepare a concentrated paste with a bleeding rate of ≤1% in the thickener unit; the concentrated paste dispensed from the thickener unit, the curing agent dispensed from the curing agent additive machine, and the composite activator dispensed from the composite activator additive machine are used to prepare the phosphorus tailings modified green backfill material in the high-speed flexible mixer.

5. The phosphorus tailings modified green backfill material preparation system according to claim 4, characterized in that, The paste storage and thickening machine includes: Warehouse body; A pulping component, which is disposed in the bin and is used to aerate and loosen the sand at the end of the middle plate of the bin. A conical silo bottom is provided on the horizontal silo bottom of the paste storage thickener. The outwardly expanding end of the conical silo bottom is sealed to the inner wall of the silo, and its contracted end abuts against the horizontal silo bottom. The contracted end of the conical silo bottom is provided with a sand discharge port, and the sand discharge port of the conical silo bottom is sealed to the sand discharge port of the horizontal silo bottom.

6. The phosphorus tailings modified green backfill material preparation system according to claim 5, characterized in that, The tiered drainage system is provided at the top of the silo.

7. The phosphorus tailings modified green backfill material preparation system according to claim 4, characterized in that, The discharge ports of the alkaline modifier additive machine, the flocculant additive machine, the paste storage thickener, the curing agent additive machine, and the composite activator additive machine are all equipped with concentration meters and flow meters.

8. The phosphorus tailings modified green backfill material preparation system according to claim 4, characterized in that, The high-speed flexible mixer is equipped with a buffer hopper at the discharge port.

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