Preparation method and system of phosphorus tailing modified green backfill material

Abstract

The invention provides a preparation method and system of a phosphorus tailing modified green backfill material, and belongs to the field of phosphorus tailing treatment.The preparation method of the phosphorus tailing modified green backfill material comprises the following steps that an alkaline blender is added into phosphorus tailing mortar, and modified slurry is prepared; injecting the modified slurry into a thickener unit, and adding a flocculating agent to prepare concentrated paste with the bleeding rate of less than or equal to 1%; the thickener unit comprises at least two paste storage thickeners; and adding a curing agent and a composite water reducer into the concentrated paste to prepare the phosphorus tailing modified green backfill material. The curing agent comprises active waste residues and a composite exciting agent. According to the method, the phosphorus tailings are modified firstly, and P, F and the like of the phosphorus tailings are preliminarily cured while the flocculating settling effect is improved; then, the concentration time of the modified slurry is prolonged, and concentrated paste with the bleeding rate smaller than or equal to 1% is obtained; and finally, by means of a curing agent and a composite water reducing agent, the flowability of the concentrated paste is improved while P, F and the like are cured, and the high-performance green backfill material is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of phosphorus tailings treatment, and particularly to a preparation method and system for a modified green backfill material for phosphorus tailings. Background Art

[0002] Tailings-free mines have become the general trend of mine exploitation. The treatment of underground phosphorus mine tailings generally involves first filling them into the underground voids. After the voids are filled, the remaining part of the tailings is wet-discharged to the tailings pond for storage. Currently, the capacity of the tailings pond is tight. If the tailings are backfilled into open pits or subsidence pits (many mine exploitations leave large areas of open pits or subsidence pits), it can not only solve the problem of the tight capacity of the tailings pond, but also contribute to the restoration of the landform, and it is increasingly becoming the mainstream of tailings treatment.

[0003] However, there are higher requirements for backfilling phosphorus tailings into open pits or subsidence pits. The conventional method is mainly to directly prepare the tailings into a filling slurry for backfilling, that is, only a flocculant is added for concentration during the preparation of the filling slurry. However, the pH value of the phosphorus tailings slurry in the concentrator is 5-6, that is, the phosphorus tailings slurry is weakly acidic, which will not only affect the flocculation settlement effect and the strength of the backfill body is low, but also the pH value of the leachate of the backfill body prepared by this method does not meet the standard (the pH value standard is 6-9), and the total phosphorus and soluble fluoride content exceed the standard (the reference standard is GB8978-1996), which is not conducive to environmental protection. Summary of the Invention

[0004] In view of the technical problems existing in the background art, the present application provides a preparation method and system for a modified green backfill material for phosphorus tailings, aiming to solve the technical problem that the leachate of the backfill body does not meet the standard caused by directly backfilling the tailings prepared into a filling slurry.

[0005] In a first aspect, an embodiment of the present application provides a preparation method for a modified green backfill material for phosphorus tailings, including the following steps: S1. Add an alkaline conditioner to the phosphorus tailings slurry to prepare a modified slurry; S2. Inject the modified slurry into a thickener unit, and add a flocculant to prepare a concentrated paste with a bleeding rate ≤ 1%; the thickener unit includes at least two paste storage thickeners; S3. Add a curing agent and a compound water reducer to the concentrated paste to prepare a modified green backfill material for phosphorus tailings; the curing agent includes active waste residue and a compound activator.

[0006] In the technical solution of the embodiment of the present application, by first adding an alkaline conditioner to the phosphorus tailings mortar and then performing flocculation sedimentation, the flocculation sedimentation effect is improved, and the alkaline conditioner and the flocculant cooperate with each other to convert soluble phosphorus, fluorine, etc. in the phosphorus tailings mortar into poorly soluble precipitates and solidify them in the tailings; then the modified slurry is injected into a thickener unit containing at least two paste storage thickeners, and a flocculant is added. By reasonably switching the use process of the paste storage thickeners, the concentration time of the modified slurry in the paste storage thickeners is extended, and then a high-concentration concentrated paste with a bleeding rate ≤ 1% is obtained; finally, the concentrated paste is mixed with a curing agent and a compound water reducer. The curing agent and the alkaline conditioner cooperate to solidify elements such as P and F in the concentrated paste in the backfill body; the compound water reducer can improve the fluidity of the concentrated paste while maintaining the bleeding rate of the concentrated paste, and finally a green backfill material with qualified leachate, extremely low bleeding rate and good fluidity is obtained, realizing the ecological restoration of open pits or subsidence pits, and solving the problems of phosphorus tailings disposal and ecological restoration.

[0007] In some embodiments, in step S3, 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, slaked lime, gypsum, sodium hydroxide, and water glass.

[0008] In this embodiment, by reasonably setting the components of the active waste residue and the composite activator, under the synergistic action of the active waste residue and the composite activator, F and P in the concentrated paste are further solidified in the backfill body.

[0009] In some embodiments, in step S3, the addition amount of the curing agent is 5% - 15% of the total mass of the dry basis of the phosphorus tailings and the curing agent; the mass ratio of the active waste residue to the composite activator in the curing agent is (85% - 95%):(5% - 15%).

[0010] In this embodiment, by reasonably controlling the addition amount of the curing agent, while efficiently solidifying elements such as P and F in the phosphorus tailings, excessive use of the curing agent is avoided, so that the strength of the obtained green backfill material reaches above the design strength requirement (0.5 - 2 MPa) in 28 days. The obtained green backfill material has relatively high strength, ensuring the long-term effectiveness of the backfill effect.

[0011] In some embodiments, step S2 is specifically: injecting the modified slurry into different paste storage thickeners in turn, so that the concentration time of the modified slurry in the paste storage thickener ≥ 12 h; the paste storage thickener includes a static concentration mode, a dynamic balance mode, and a pneumatic activation mode.

[0012] In this embodiment, by switching between different paste storage thickeners and between different functions of each paste storage thickener, it is always ensured that the concentration time of the modified slurry in the paste storage thickener is ≥ 12 h, so as to obtain a concentrated paste with a bleeding rate ≤ 1%, reduce the backfill cost, and improve the environmental protection performance.

[0013] In some embodiments, in step S1, the alkaline conditioner includes one or more of quicklime and slaked lime.

[0014] In this embodiment, by reasonably setting the composition of the alkaline conditioner, the soluble phosphorus in the phosphorus tailings sand is converted into insoluble hydroxyphosphate precipitate, and the fluoride ions are converted into insoluble fluoride precipitate and solidified in the backfill body.

[0015] In a second aspect, an embodiment of the present application provides a preparation system for a phosphorus tailings sand modified green backfill material, which is used for the method for preparing the phosphorus tailings sand modified green backfill material provided in the first aspect of the present application, and 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 sand incoming pipe from the concentrator, and an alkaline conditioner adding machine, and the feed ports of the mixer are respectively communicated with the discharge port of the phosphorus tailings sand incoming pipe from the concentrator and the discharge port of the alkaline conditioner adding machine; the concentrated paste preparation unit includes a thickener unit and a flocculant adding machine, the thickener unit includes at least two paste storage thickeners, and the feed ports of each paste storage thickener are respectively communicated with the discharge port of the mixer and the discharge port of the flocculant adding machine; the green backfill material preparation unit includes a high-speed flexible mixer, a curing agent adding machine, and a composite activator adding machine, and the feed ports of the high-speed flexible mixer are respectively communicated with the discharge port of the curing agent adding machine and the discharge port of the composite activator adding machine; the alkaline conditioner released by the alkaline conditioner adding machine and the phosphorus tailings sand slurry released by the phosphorus tailings sand incoming pipe from the concentrator are prepared into the modified slurry in the mixer; the modified slurry released by the mixer and the flocculant released by the flocculant adding machine are prepared into a concentrated paste with a bleeding rate ≤ 1% in the thickener unit; the concentrated paste released by the thickener unit, the curing agent released by the curing agent adding machine, and the composite activator released by the composite activator adding machine are prepared into the phosphorus tailings sand modified green backfill material in the high-speed flexible mixer.

[0016] In the technical solution of the embodiment of the present application, by setting a mixer to fully modify the phosphorus tailings, not only can the effect of subsequent flocculation sedimentation be improved, but also soluble phosphorus, fluorine, etc. in the phosphorus tailing slurry can be converted into poorly soluble precipitates and solidified in the tailings; by setting a thickener unit, the use process of the paste storage thickener is reasonably switched during the flocculation sedimentation process, so as to extend the concentration time of the modified slurry in the paste storage thickener, and then a high-concentration concentrated paste with a bleeding rate ≤ 1% is obtained; by setting a green backfill material preparation unit, the concentrated paste is fully mixed and interacted with the curing agent and the compound water reducer, and elements such as P and F in the concentrated paste are further solidified in the backfill body, reducing the content of P and F in the leachate of the backfill body, and at the same time improving the fluidity of the concentrated paste.

[0017] In some embodiments, the paste storage thickener includes: a tank body; a slurry-making component, which is arranged in the tank body and is used for aerating and loosening the tailings at the end of the middle plate in the tank body; a conical tank bottom, which is arranged on the horizontal tank bottom of the paste storage thickener, the outer expanding end of the conical tank bottom is hermetically connected to the inner wall of the tank body, its shrinking end abuts against the horizontal tank bottom, and a sand discharge port is provided at the shrinking end of the conical tank bottom, and the sand discharge port of the conical tank bottom is hermetically connected to the sand discharge port of the horizontal tank bottom.

[0018] In this embodiment, setting the tank bottom of the tank body as a conical tank bottom can improve the sedimentation efficiency of phosphorus tailings particles; by setting a slurry-making component, the tailings at the end of the middle plate in the tank body can be aerated and loosened, realizing the pneumatic activation mode of the paste storage thickener.

[0019] In some embodiments, a stepped drainage system is provided at the top of the tank body.

[0020] In this embodiment, by setting a stepped drainage system, the clear water at the upper part of the slurry can be released to the greatest extent according to the different heights of the slurry in the tank body, which is convenient for the smooth progress of the pneumatic activation mode.

[0021] In some embodiments, concentration meters and flow meters are provided at the discharge port ends of the alkaline conditioner adding machine, the flocculant adding machine, the paste storage thickener, the curing agent adding machine, and the composite activator adding machine.

[0022] In this embodiment, by setting concentration meters and flow meters, it is convenient to detect the adding concentration and adding flow of the alkaline conditioner, flocculant, curing agent, and composite activator, as well as the concentration of the slurry discharged from the paste storage thickener, ensuring the accurate addition of different materials and the bleeding rate of the concentrated paste ≤ 1%.

[0023] In some embodiments, a buffer hopper is provided at the discharge port end of the high-speed flexible mixer.

[0024] In this embodiment, a buffer hopper is provided at the discharge port end of the high-speed flexible mixer, which can buffer and regulate the phosphorus tailings modified green backfill material for subsequent transportation.

[0025] The above description is only an overview of the technical solution of the present application. In order to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of a phosphorus tailings modified green backfill material preparation system in an embodiment of the present application; Figure 2 It is a schematic structural diagram of the first paste storage thickener in an embodiment of the present application; Description of reference numerals: 100 - phosphorus tailings modified green backfill material preparation system; 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 incoming pipe from the concentrator; 13 - alkaline conditioner adding machine; 21 - flocculant adding machine; 22 - first paste storage thickener; 23 - second paste storage thickener; 31 - high-speed flexible mixer; 32 - curing agent adding machine; 33 - composite activator adding machine; 221 - tank body; 222 - conical tank bottom; 223 - horizontal tank bottom; 224 - sand discharge port; 225 - stepped drainage system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The embodiments of the technical solution of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0030] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is more than two, unless otherwise clearly and specifically defined.

[0031] Referring to "embodiment" herein means that the specific features, structures, or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The occurrence of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0032] In the description of the embodiments of the present application, the term "a plurality of" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0033] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "top", "bottom", "inner", and "outer" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of the present application.

[0034] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", and "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0035] Tailing-free mines have become the general trend of mine exploitation, and filling phosphorus tailings into open pits or subsidence pits has increasingly become the mainstream of tailings treatment. The conventional method for preparing the backfill body is mainly to prepare the tailings into a filling slurry and directly backfill it. However, the pH value of the leachate from the backfill body prepared by this method does not meet the standard (the pH value standard is 6 - 9), and the total phosphorus and soluble fluoride content in the leachate from the backfill body exceed the standard (the reference standard is GB8978 - 1996), which is not conducive to environmental protection.

[0036] In order to solve the technical problem that the leachate from the backfill body fails to meet the standard when tailings are prepared into filling slurry for direct backfilling, the present application provides a method and system for preparing a modified green backfill material from phosphorus tailings. Among them, by first adding an alkaline conditioner to the phosphorus tailing slurry and then performing flocculation sedimentation, the flocculation sedimentation effect is improved, and the alkaline conditioner and the flocculant cooperate with each other to convert soluble phosphorus, fluorine, etc. in the phosphorus tailing slurry into poorly soluble precipitates and solidify them in the tailings. Then, the modified slurry is injected into a thickener unit containing at least two paste storage thickeners, and a flocculant is added. By reasonably switching the use process of the paste storage thickeners, the concentration time of the modified slurry in the paste storage thickeners is extended, and thus a high-concentration concentrated paste with a bleeding rate ≤ 1% is obtained. Finally, the concentrated paste is mixed with a curing agent and a compound water reducer. The curing agent and the alkaline conditioner cooperate to solidify elements such as P and F in the concentrated paste in the backfill body. The compound water reducer can improve the fluidity of the concentrated paste while maintaining the bleeding rate of the concentrated paste, and finally a green backfill material with qualified leachate, extremely low bleeding rate and good fluidity is obtained, realizing the ecological restoration of open pits or subsidence pits, and solving the problems of phosphorus tailings disposal and ecological restoration. The backfill and collaborative ecological restoration scheme for open pits or subsidence pits in the present application can not only dispose of tailings and solve the problem of the whereabouts of tailings, but also repair the environment, killing two birds with one stone.

[0037] The flotation process is adopted in phosphate ore beneficiation, resulting in most phosphorus tailings being extremely fine tailings (extremely fine tailings generally refer to those with the content of tailings particles -20μm accounting for more than 50%). When extremely fine tailings are concentrated in a thickener, after the tailings particles are mixed with the flocculant, the molecular chain of the flocculant wraps the tailings particles and a large number of water molecules to form flocs, and the water wrapped therein is difficult to precipitate in a short time, thus forming a relatively loose slurry in the thickener and reducing the concentration of the slurry discharged from the thickener. At the same time, the height of the side wall of the vertical section of a conventional deep cone thickener is generally 10m. In order to avoid pressing the rake, the height of the mud layer formed by the tailings flocs in the thickener generally cannot exceed 7m, and there is a rake frame at the bottom of the thickener, so that the storage space and time of the tailings in the thickener are limited, further affecting the concentration effect. Moreover, the tailings treatment capacity of a conventional thickener is small (0.3 - 0.5t / m 2 ·h), with low efficiency, great difficulty in flocculation sedimentation, large consumption of flocculant, and easy mud running. Eventually, the concentration of the slurry discharged from the thickener is low and a paste cannot be formed, and at the same time, the backfill cost and environmental protection risk will be increased.

[0038] In addition, backfilling open pits or subsidence pits is only for tailings disposal and ecological restoration, and cannot bring economic benefits to enterprises. If the costs of backfilling and ecological restoration are too high, the economic benefits of enterprises will be damaged, and in the long run, enterprises will find it difficult to bear. Generally, the costs of building and operating a tailings pond are allocated to tailings at 40 yuan / t dry basis. Therefore, enterprises are committed to controlling the direct cost of backfilling open pits or subsidence pits within 40 yuan / t, which is equivalent to the cost of building a tailings pond.

[0039] In a first aspect, an embodiment of the present application provides a method for preparing a modified green backfill material for phosphorus tailings, including the following steps: S1. Add an alkaline conditioner 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 thickening settlement, solidification and ecological restoration of tailings. Therefore, before thickening settlement, the phosphorus tailings are modified with an alkaline conditioner. On the one hand, it can improve the effect of flocculation settlement, and on the other hand, it can convert soluble phosphorus, fluorine, etc. in the phosphorus tailings slurry into poorly soluble precipitates and solidify them in the tailings.

[0040] S2. Inject the modified slurry into the thickener unit and add a flocculant to prepare a concentrated paste with a bleeding rate ≤ 1%. Among them, the thickener unit includes at least two paste storage thickeners. Specifically, by setting at least two paste storage thickeners and reasonably switching the use 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 obtained concentrated paste fluctuates within ± 2%, and then a high-concentration concentrated paste with a bleeding rate ≤ 1% is obtained, that is, an extreme paste is obtained.

[0041] S3. Add a curing agent and a compound water reducer to the concentrated paste to prepare a modified green backfill material for phosphorus tailings; among them, the curing agent includes active waste residue and a compound activator. Specifically, the curing agent is a new type of cementitious material for phosphorus tailings, using slag and yellow phosphorus slag with potential activity (i.e., containing components such as Ca, Al, SiO2, etc.) as the main bulk materials, and at the same time using a compound activator for activation to further solidify elements such as P and F in the concentrated paste. The main components of the compound water reducer are polycarboxylic acid, modified lignosulfonate, air-entraining agent, retarder, etc., among which the mass ratio of polycarboxylic acid is 30%-40%, and the mass ratio of modified lignosulfonate is 30%-35%. The air-entraining agent includes one or more of sodium dodecyl sulfate, modified rosin (such as rosin triethanolamine salt), etc. Its main function is to introduce uniform and stable microbubbles to improve the workability and durability of the paste slurry; the addition amount of the compound water reducer is generally 300-700 g / t dry basis. The compound water reducer can improve the fluidity of the concentrated paste while maintaining the bleeding rate of the concentrated paste, so that the backfill body is easier to backfill into the open pit or subsidence pit.

[0042] In the technical solution of the embodiment of the present application, before flocculation sedimentation, an alkaline conditioner is first added to the phosphorus tailings mortar to modify the phosphorus tailings. On the one hand, it can improve the effect of subsequent flocculation sedimentation. On the other hand, it can cooperate with the flocculant to convert soluble phosphorus, fluorine (arsenic is basically not contained in the phosphorus tailings mortar), etc. in the phosphorus tailings mortar into poorly soluble precipitates and solidify them in the tailings. Then, 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 and reasonably switching the use process of the paste storage thickeners during the flocculation sedimentation process, the concentration time of the modified slurry in the paste storage thickeners is extended, and then a high-concentration concentrated paste with a bleeding rate ≤ 1% (i.e., an ultimate paste) is obtained. Finally, the concentrated paste is mixed with a curing agent and a compound water reducer. The curing agent can further solidify elements such as P and F in the concentrated paste in the backfill body, reduce the content of P and F in the leachate of the backfill body, avoid secondary pollution to the surrounding environment caused by the backfill body, meet the environmental protection standards, and achieve ecological restoration. The compound water reducer can improve the fluidity of the concentrated paste while maintaining the bleeding rate of the concentrated paste, so that the backfill body is more easily backfilled into the open pit or collapse pit, and finally a green backfill material with qualified leachate (the reference standard is GB 8978-1996 "Integrated Wastewater Discharge Standard"), extremely low bleeding rate, and good fluidity is obtained, realizing the ecological restoration of the open pit or collapse pit. At the same time, the alkaline conditioner, curing agent, and compound water reducer used in the present application have low costs, so that the backfill cost is controlled within 35 yuan / t dry basis.

[0043] Further, in some embodiments, in step S3, 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, slaked lime, gypsum, sodium hydroxide, water glass, etc.

[0044] In the technical solution of the embodiment of the present application, by reasonably setting the components of the active waste residue and the composite activator, first, F, P, etc. 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, and finally calcium silicoaluminate gel is formed, that is, F and P in the concentrated paste are further solidified in the backfill body.

[0045] Further, in some embodiments, in step S3, the addition amount of the curing agent is 5% - 15% of the total mass of the phosphorus tailings dry basis and the curing agent; the mass ratio of the active waste residue to the composite activator in the curing agent is (85% - 95%):(5% - 15%).

[0046] In the technical solution of the embodiment of the present application, by reasonably controlling the addition amount of the curing agent, while efficiently curing elements such as P and F in the phosphorus tailings, the excessive use of the curing agent is avoided, so as to control the final setting time within 24 hours, and at the same time make the strength of the obtained green backfill material reach more than the design strength requirement (0.5 - 2 MPa) in 28 days. The obtained green backfill material has relatively high strength, ensuring the long-term effectiveness of the backfill effect.

[0047] Further, in some embodiments, step S2 is specifically as follows: The modified slurry is alternately injected into different paste storage thickeners, so that the concentration time of the modified slurry in the paste storage thickener is ≥ 12 h; The paste storage thickener includes a static concentration mode, a dynamic balance mode, and a pneumatic activation mode. Specifically, in the conventional thickening process, the maximum concentration time of the tailings in the thickener is 8 h. The tailings slurry in the thickener from top to bottom in the vertical direction is successively a clear water layer, a sedimentation layer, a compression layer, and a dense layer. The concentration of the tailings slurry increases successively from top to bottom, and the concentration of the tailings slurry in the dense 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 ≥ 12 h, the concentration of the tailings slurry in the dense layer of the paste storage thickener can be greatly increased, and a concentrated paste with a bleeding rate ≤ 1% can be obtained.

[0048] In the technical solution of the embodiment of the present application, each paste storage thickener has three modes: a static concentration mode, a dynamic balance mode, and a pneumatic activation mode. Through the mutual switching of different paste storage thickeners and the mutual switching of different functions of each paste storage thickener, it is always ensured that the concentration time of the modified slurry in the paste storage thickener is ≥ 12 h, ensuring that the phosphorus tailings have sufficient concentration time, so as to obtain a concentrated paste with a bleeding rate ≤ 1%, reduce the backfill cost, and improve the environmental protection performance.

[0049] Further, in some embodiments, in step S1, the alkaline conditioner includes one or more of quicklime, slaked lime, etc. Specifically, one or more of quicklime, slaked lime, etc. are prepared into a slurry with a certain concentration to obtain the alkaline conditioner. The addition amount of the alkaline conditioner solution is 1 - 2 m³ / h, which is equivalent to the addition amount of the alkaline conditioner being 1 - 2 kg / t of dry basis tailings amount.

[0050] In the technical solution of the embodiment of the present application, by reasonably setting the composition of the alkaline conditioner, the soluble phosphorus in the phosphorus tailings reacts with calcium oxide or calcium hydroxide to form insoluble hydroxyphosphate precipitates and solidify in the modified slurry, and the fluoride ions react with calcium oxide or calcium hydroxide to form insoluble fluoride precipitates and solidify in the modified slurry. By reasonably setting the addition amount of the alkaline conditioner, while ensuring the preliminary solidification of the soluble phosphorus and fluorine in the phosphorus tailings, the excessive use of the alkaline conditioner is avoided, which may affect the strength and pH value of the finally prepared backfill body.

[0051] Please refer to Figure 1 Second, an embodiment of the present application provides a preparation system 100 for a modified green backfill material of phosphorus tailings, which is used for the above-mentioned preparation method of the modified green backfill material of phosphorus tailings, and includes: a modified slurry preparation unit 1, a concentrated paste preparation unit 2, and a green backfill material preparation unit 3 that are connected in sequence; the modified slurry preparation unit 1 includes a mixer 11, a phosphorus tailings incoming material pipe 12 from the concentrator, and an alkaline conditioner adding machine 13. The feed ports of the mixer 11 are respectively communicated with the discharge port of the phosphorus tailings incoming material pipe 12 from the concentrator and the discharge port of the alkaline conditioner adding machine 13; the concentrated paste preparation unit 2 includes a thickener unit and a flocculant adding machine 21. The thickener unit includes 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 feed ports of each paste storage thickener are respectively communicated with the discharge port of the mixer 11 and the discharge port of the flocculant adding machine 21; the green backfill material preparation unit 3 includes a high-speed flexible mixer 31, a curing agent adding machine 32, and a composite activator adding machine 33. The feed ports of the high-speed flexible mixer 31 are respectively communicated with the discharge port of the curing agent adding machine 32 and the discharge port of the composite activator adding machine 33. Specifically, pumping devices are provided at the discharge port ends of the mixer 11, the phosphorus tailings incoming material pipe 12 from the concentrator, the alkaline conditioner adding machine 13, the flocculant adding machine 21, the paste storage thickener, the high-speed flexible mixer 31, the curing agent adding machine 32, and the composite activator adding machine 33. A variable-frequency centrifugal feeding pump is used to pump the alkaline conditioner and the phosphorus tailings slurry from the concentrator into the mixer 11 respectively, so that the phosphorus tailings slurry and the alkaline conditioner 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 adding 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 adding machine 32, and the composite activator discharged from the composite activator adding machine 33 are activated and stirred in the high-speed flexible mixer 31 (with a rotation speed above 200 r / min and a stirring time not less than 3 min) to prepare a modified green backfill material of phosphorus tailings. The specific process of preparing the concentrated paste is as follows: In the technical solution of the embodiment of the present application, by setting the mixer 11, the full mixing of the phosphorus tailing mortar in the beneficiation plant and the alkaline conditioner is realized, and the modification of the phosphorus tailings is achieved. This not only improves the effect of subsequent flocculation sedimentation, but also converts soluble phosphorus, fluorine, etc. in the phosphorus tailing mortar into poorly soluble precipitates and solidifies them in the tailings. By setting the thickener unit, it is ensured that the thickener unit includes at least two paste storage thickeners, and the use process of the paste storage thickeners is reasonably switched during the flocculation sedimentation process, so as to extend the concentration time of the modified slurry in the paste storage thickener, and then obtain a high-concentration concentrated paste with a bleeding rate ≤ 1% (i.e., the ultimate paste). By setting the high-speed flexible mixer 31, the curing agent adding machine 32 and the composite activator adding machine 33, the concentrated paste is fully mixed and interacted with the curing agent and the composite water reducer, further solidifying elements such as P and F in the concentrated paste in the backfill body, reducing the content of P and F in the leachate of the backfill body, and at the same time improving the fluidity of the concentrated paste, so that the backfill body is more easily backfilled into the open pit or the collapse pit.

[0052] Further, in some embodiments, the structures of the first paste storage thickener 22 and the second paste storage thickener 23 are the same. Taking the first paste storage thickener 22 as an example for illustration. As Figure 2 shown, the first paste storage thickener 22 includes: a tank body 221; a pulp-making component, which is arranged in the tank body 221 and is used for aerating and loosening the tailings at the end of the plate in the tank body 221; a conical tank bottom 222, which is arranged on the horizontal tank bottom 223 of the first paste storage thickener 22. The outer expanding end of the conical tank bottom 222 is hermetically connected to the inner wall of the tank body 221, its contracting end abuts against the horizontal tank bottom 223, and a sand discharge port 224 is provided at the contracting end of the conical tank bottom 222. The sand discharge port 224 of the conical tank bottom 222 is hermetically connected to the sand discharge port 224 of the horizontal tank bottom 223. For other detailed structures of the first paste storage thickener 22 and the second paste storage thickener 23, refer to the patent with the application number CN202322371733.3, which will not be elaborated here.

[0053] In the technical solution of the embodiment of the present application, setting the bottom of the tank body 221 as the conical tank bottom 222 can improve the sedimentation efficiency of the phosphorus tailing particles. The sand discharge port 224 of the tank body 221 is arranged at the contracting end of the conical tank bottom 222, and the tailings in the tank body 221 can quickly slide into the sand discharge port 224 under the guidance of the conical surface of the conical tank bottom; by setting the pulp-making component, the tailings at the end of the plate in the tank body 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, reducing the energy consumption.

[0054] Further, in some embodiments, as Figure 1 and Figure 2As shown in the figure, a stepped drainage system 225 is provided at the top of the bin body 221. The stepped drainage system 225 includes a number of drainage valves arranged vertically at different horizontal heights.

[0055] In the technical solution of the embodiment of the present application, by arranging the stepped drainage system 225 at different horizontal heights at the top of the bin body 221, the clear water in the upper part of the slurry can be released to the greatest extent according to the different heights of the slurry in the bin body 221, which is convenient for the smooth progress of the pneumatic activation mode.

[0056] Furthermore, in some embodiments, concentration meters and flow meters are provided at the discharge port ends of the alkaline conditioner adding machine 13, the flocculant adding machine 21, the paste storage thickener, the curing agent adding machine 32, and the composite activator adding machine 33.

[0057] In the technical solution of the embodiment of the present application, by arranging a concentration meter and a flow meter at the discharge port ends of the alkaline conditioner adding machine 13, the flocculant adding machine 21, the curing agent adding machine 32, and the composite activator adding machine 33, it is convenient to detect the adding concentration and adding flow rate of the alkaline conditioner, the flocculant, the curing agent, and the composite activator. By arranging a concentration meter at the discharge port end of the paste storage thickener, it is convenient to monitor the concentration of the slurry discharged from the paste storage thickener in real time to ensure that the water bleeding rate of the concentrated paste is ≤ 1%; when the concentration of the slurry discharged from the paste storage thickener is lower than the preset value, the sand discharge port 224 of the bin body 221 is closed, so that the slurry in the bin body 221 is further subjected to flocculation sedimentation until the sand discharge requirement is met.

[0058] The specific process of modified slurry flocculation and sedimentation is as follows: (1) The modified slurry discharged from the mixer 11 first enters the first paste storage thickener 22 until the first paste storage thickener 22 reaches the preset feed volume (generally referring to reaching the maximum feed slurry, that is, the full state, and the feed time ≥ 12 h), and the static concentration mode is realized; (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 volume (the feed time ≥ 12 h), and the static concentration mode is realized; (3) At this time, the concentration time of the first paste storage thickener 22 meets ≥ 12 h, and the first paste storage thickener 22 enters the dynamic balance mode. When the concentration meter at the discharge port end of the first paste storage thickener 22 detects that the concentration of the discharged concentrated paste is less than the preset value (that is, the water bleeding rate of the concentrated paste > 1%), stop discharging sand; (4) The second paste storage thickener 23 enters the dynamic balance mode (since the feed time ≥ 12 h, and the first paste storage thickener 22 entering the dynamic balance mode will also consume a certain amount of time, so the concentration time can meet ≥ 12 h when the second paste storage thickener 23 enters the dynamic balance mode). When the concentration meter at the discharge port end of the second paste storage thickener 23 detects that the concentration of the discharged concentrated paste is less than the preset value (that is, the water bleeding rate of the concentrated paste > 1%), stop discharging sand; (5) Then switch to the first paste storage thickener 22 to enter the dynamic balance mode; (6) Before discharging sand from the first paste storage thickener 22 or the second paste storage thickener 23, first discharge the excess water of the supernatant through the stepped drainage system 225, and then start the pulp-making component to realize pulp-making and sand discharging, that is, realize the pneumatic activation mode. When the first paste storage thickener 22 is in the dynamic balance mode, the second paste storage thickener 23 can be in the pneumatic activation mode. That is, by continuously switching the working mode between the first paste storage thickener 22 and 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 discharge port ≤ 1% is realized.

[0059] Furthermore, in some embodiments, a buffer bucket 4 is provided at the discharge port end of the high-speed flexible mixer 31. Specifically, after the preparation of the phosphorus tailings modified green backfill material is completed, it first enters the buffer bucket 4 for buffering and adjustment, and then is pumped to the nearest backfill pit 6 (i.e., an open pit or a collapsed pit) by a centrifugal filling pump 5. The centrifugal filling pump 5 is improved and optimized on the basis of the centrifugal slurry pump, so that its pump impeller is larger in size and higher in strength; the motor has a higher power to adapt to the transportation of the phosphorus tailings modified green backfill material. During the transportation process of the phosphorus tailings modified green backfill material, the centrifugal filling pump 5 will shear the phosphorus tailings modified green backfill material, and can stir the phosphorus tailings modified green backfill material again, further improving its fluidity and reducing the transportation resistance. The conveying distance requirement of the centrifugal filling pump 5 is less than about 1 km, and the height difference is 0 m or less. In the process of backfilling the backfill pit 6, the principle of "division and layering" is adopted, that is, each layer of the entire area of ​​the backfill pit 6 is divided into small units, and the area of ​​each unit is controlled within 70×70m according to the on-site conditions. 2 Within, the layer height is ≤1.5m, a water filter pipe is laid at the bottom and a drainage ditch is made around it, and a very small amount of filtered water from the phosphorus tailings modified green backfill material is collected in a temporary sump of each layer, and then pumped to a special water treatment plant by a return pump 7 to ensure that the filtered water is not discharged.

[0060] In the technical solution of the embodiment of the present application, by providing a buffer bucket 4 at the discharge port end of the high-speed flexible mixer 31, the phosphorus tailings modified green backfill material can be buffered and adjusted to facilitate subsequent transportation.

[0061] The present invention is described in detail below through specific embodiments.

[0062] Example 1 A method for preparing phosphorus tailings modified green backfill material comprises the following steps: S1. Prepare quicklime into a slurry with a mass concentration of 13% to obtain an alkaline conditioning agent, and add the alkaline conditioning agent to the phosphorus tailings mortar. The amount of the alkaline conditioning agent solution added is 1.8 m 3 / h, which is equivalent to 1.8kg / t of quicklime added per ton of dry tailings, to prepare modified slurry. The pH value of the modified slurry obtained is 7-8, and the mass concentration is 30%.

[0063] S2. Inject the modified slurry into the thickener unit and add anionic polyacrylamide flocculant. By reasonably switching the use process of the paste storage thickener, inject the modified slurry into different paste storage thickeners in turn, extend the concentration time of the modified slurry in the paste storage thickener, make the concentration time of the modified slurry in the paste storage thickener ≥12h, make the sand concentration of the thickener be in an extreme paste state, and obtain a concentrated paste with a water seepage rate of 0.8%.

[0064] S3. Add a curing agent and a compound water reducer to the concentrated paste to prepare a phosphorus tailings modified green backfill material; among them, the curing agent includes active waste residues and a compound activator. Specifically, the curing agent is a slag with potential activity (for example, a by-product generated during the high-temperature smelting of ore in the iron and steel industry of the metallurgical industry, whose main components are inorganic oxides such as silicates and aluminates and has potential cementitious activity) and a compound activator (prepared by mixing quicklime and gypsum at a mass ratio of 1:1) compounded at a mass ratio of 90%:10%. The addition amount of the curing agent is 10% of the total mass of the dry basis of phosphorus tailings and the curing agent (i.e., the total dry basis mass); the main components of the compound water reducer are polycarboxylic acid, modified lignosulfonate, air-entraining agent, retarder, etc. Among them, the mass fraction of polycarboxylic acid is 35%, the mass fraction of modified lignosulfonate is 32%, the air-entraining agent is composed of rosin, and its mass fraction is 0.01% - 0.1%. The retarder is mainly composed of sodium gluconate, and its mass fraction is 0.3% - 2%. The rest are water and stabilizers. The addition amount of the compound water reducer is 500 g / t of the dry basis amount.

[0065] Example 2 and Comparative Example 1 A method for preparing a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S2, the bleeding rate of the obtained concentrated paste is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0066] Perform performance tests on the phosphorus tailings modified green backfill materials prepared in Examples 1 - 2 and Comparative Example 1, and the results are shown in Table 1.

[0067] The strength test is carried out by a pressure testing machine TYE - 300; Prepare leachate water by using "Solid Waste - Extraction Procedure for Toxicity Characteristics - Sulfuric Acid and Nitric Acid Method" (HJ / T 299 - 2007) or "Horizontal Oscillation Method" (HJ 557 - 2010) (the soaking time is usually 18 ± 2 hours). Then, determine the total P content of the leachate water according to "Water Quality - Determination of Total Phosphorus - Ammonium Molybdate Spectrophotometric Method" (GB 11893 - 89), determine the F content of the leachate water according to "Water Quality - Determination of Fluoride - Ion Selective Electrode Method" (GB 7484 - 87), and detect the pH value by using a pH meter.

[0068] Table 1 Performance of the phosphorus tailings modified green backfill materials in Examples 1 - 2 and Comparative Example 1 As can be seen from Table 1, when the bleeding rate of the concentrated paste ≤ 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 (total phosphorus content) and F content are relatively low, and the leachate meets the discharge standards specified in GB8978-1996 (in the discharge standards, F content ≤ 10 mg / L, total P content ≤ 0.5 mg / L). When the bleeding rate of the concentrated paste is 1.2%, the 28-day strength of the obtained phosphorus tailings modified green backfill material is relatively low, and the pH value of the leachate exceeds 9, and the P content and F content also increase. This may be because, as the bleeding rate of the concentrated paste increases, it indicates that the mass concentration of the concentrated paste gradually decreases (when the bleeding rate is 0.8%, the mass concentration is about 67%; when the bleeding rate is 1%, the mass concentration is about 65%; when the bleeding rate is 1.2%, the mass concentration is about 63%). When the mass concentration of the concentrated paste decreases, after its interaction with the curing agent and the compound water reducer, the strength of the obtained phosphorus tailings modified green backfill material is on the low side, and the curing effect of the curing agent on P and F will also be weakened, thus affecting the composition and content of the leachate.

[0069] Examples 3-4 and Comparative Examples 2-3 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S3, the mass ratio of the slag with potential activity and the compound activator in the curing agent is different, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0070] The phosphorus tailings modified green backfill materials prepared in Examples 3-4 and Comparative Examples 2-3 were subjected to performance tests, and the results are shown in Table 2.

[0071] Table 2 Performance of the phosphorus tailings modified green backfill materials in Examples 3-4 and Comparative Examples 2-3 As can be seen from Table 2, within a certain range, as the mass ratio of the slag with potential activity and the compound activator in the curing agent continuously increases, the 28-day strength of the obtained phosphorus tailings modified green backfill material and the pH of the leachate gradually decrease, and the P content and F content 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 the slag with potential activity and the compound activator in the curing agent affects the reaction between F, P, etc. in the concentrated paste and the compound activator and the slag to a certain extent, thus affecting the curing effect of the curing agent on P and F in the phosphorus tailings, and at the same time affecting the structure and strength of the obtained phosphorus tailings modified green backfill material.

[0072] When the content of slag with potential activity in the curing agent is too high, and the content of the composite activator is too low at this time, it will affect the full reaction of F, P, etc. in the concentrated paste with the curing agent, affecting the coating effect of the curing agent on F and P, that is, affecting the curing effect, and at the same time affecting the structure of the phosphorus tailings modified green backfill material, that is, affecting its strength.

[0073] When the content of slag with potential activity in the curing agent is too low, and the content of the composite activator is too high at this time, although F, P, etc. in the concentrated paste can fully react with quicklime to form precipitates, but since the slag content is relatively small at this time, it cannot interact well with the precipitates, thus affecting the coating effect of the curing agent on F and P. And because the dosage of the composite activator is too high, the pH of the leachate is too high, exceeding the standard, and the cost increases. This shows that the ratio of the slag with potential activity in the curing agent to the composite activator needs to be within a reasonable range to achieve a better curing effect.

[0074] Examples 5 - 6 and Comparative Examples 4 - 5 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S3, the addition amount of the curing agent is different, and the others are roughly the same as in Example 1, which will not be elaborated here.

[0075] The phosphorus tailings modified green backfill materials prepared in Examples 5 - 6 and Comparative Examples 4 - 5 were subjected to performance tests, and the results are shown in Table 3.

[0076] Table 3 Performance of the phosphorus tailings modified green backfill materials in Examples 5 - 6 and Comparative Examples 4 - 5 As can be seen from Table 3, with the increase in the addition amount of the curing agent, the 28 - day strength of the obtained phosphorus tailings modified green backfill material gradually increases, the P content and F content in the leachate gradually decrease, and the pH value gradually increases. When the addition amount of the curing agent is too large, although the strength of the obtained phosphorus tailings modified green backfill material is relatively high at this time, the cost increases significantly, and the pH value of the leachate exceeds the standard; when the addition amount of the curing agent is too small, the curing effect is poor, resulting in a significantly lower 28 - day strength of the phosphorus tailings modified green backfill material, and at the same time, the P content and F content in the leachate are relatively high.

[0077] Comparative Example 6 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S1, the phosphorus tailings mortar is not modified, that is, no alkaline conditioner is added, to ensure that the concentration of the phosphorus tailings mortar is the same as that of the modified slurry in Example 1, and the others are roughly the same as in Example 1, which will not be elaborated here.

[0078] Comparative Example 7 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S3, no curing agent is added, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0079] Comparative Example 8 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that in step S3, no compound water reducer is added, and the others are substantially the same as in Example 1, which will not be elaborated here.

[0080] Comparative Example 9 A preparation method of a phosphorus tailings modified green backfill material, compared with Example 1, the difference is that the phosphorus tailings slurry is directly prepared into a filling slurry for backfill, that is, only a flocculant is added for concentration during the preparation of the backfill material.

[0081] The phosphorus tailings modified green backfill materials prepared in Comparative Examples 6-9 were subjected to performance tests, and the results are shown in Table 4.

[0082] Table 4 Performance of the phosphorus tailings modified green backfill materials in Comparative Examples 6-9 From the data of Comparative Example 6 and Example 1 in Table 4, it can be seen that when the phosphorus tailings slurry is not modified in step S1, the performance of the obtained phosphorus tailings modified green backfill material is significantly worse. This may be because when the phosphorus tailings slurry is not modified, the phosphorus tailings slurry is weakly acidic, which affects the flocculation and sedimentation effect, and at the same time affects the bleeding rate of the obtained concentrated paste. Moreover, the composition of the obtained concentrated paste is different from that in Example 1, which further affects the interaction between the curing agent and the concentrated paste, and finally affects the structure and performance of the phosphorus tailings modified green backfill material. And because the phosphorus tailings slurry is not modified in step S1, it directly affects the pH value of the leachate.

[0083] From the data of Comparative Example 7 and Example 1, it can be seen that when no curing agent is added in step S3, the performance of the obtained phosphorus tailings modified green backfill material is significantly worse. This may be because when no curing agent is added, only the alkaline conditioner converts the soluble phosphorus, fluorine, etc. in the phosphorus tailings slurry into poorly soluble precipitates and solidifies them in the tailings, and the effective curing of P and F cannot be achieved. Moreover, when there is no curing agent, the combination of phosphorus tailings and the curing agent cannot be realized, which seriously affects the strength of the phosphorus tailings modified green backfill material.

[0084] From the data of Comparative Example 8 and Example 1, it can be seen that when no compound water reducer is added in step S3, the fluidity of the obtained phosphorus tailings modified green backfill material is significantly worse, and it is difficult to achieve the smooth backfill of the phosphorus tailings modified green backfill material.

[0085] From the data of Comparative Example 9 and Example 1, it can be seen that when the phosphorus tailings mortar is directly prepared into a filling slurry for backfilling, the performance of the obtained backfilling material is significantly poor, indicating that the method of the present application can obtain a high-performance backfilling material.

[0086] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution and the same effect as the technical idea within the technical scope of the present application are included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be conceived by those skilled in the art to the embodiments and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A preparation method of a modified green backfill material for phosphorus tailings, characterized in that, It includes the following steps: S1. Add an alkaline conditioner to the phosphorus tailings mortar to prepare a modified slurry; S2. Inject the modified slurry into the thickener unit and add a flocculant to prepare a concentrated paste with a bleeding rate ≤ 1%; the thickener unit includes at least two paste storage thickeners; S3. Add a curing agent and a compound water reducer to the concentrated paste to prepare a modified green backfill material for phosphorus tailings; the curing agent includes active waste residue and a compound activator.

2. The preparation method of the phosphorus tailings modified green backfill material according to claim 1, characterized in that, In step S3, the active waste residue includes one or two of active slag and active yellow phosphorus slag; the compound activator includes two or more of quicklime, slaked lime, gypsum, sodium hydroxide, and water glass.

3. The preparation method of the phosphorus tailing modified green backfill material according to claim 1, characterized in that, In step S3, the addition amount of the curing agent is 5% - 15% of the total mass of the dry basis of phosphorus tailings and the curing agent; the mass ratio of the active waste residue to the compound activator in the curing agent is (85% - 95%):(5% - 15%).

4. The preparation method of the phosphorus tailings modified green backfill material according to claim 1, characterized in that, Step S2 is specifically: Inject the modified slurry into different paste storage thickeners in turn, so that the concentration time of the modified slurry in the paste storage thickener ≥ 12h; the paste storage thickener includes a static concentration mode, a dynamic balance mode, and a pneumatic activation mode.

5. The preparation method of the phosphorus tailing modified green backfill material according to claim 1, characterized in that, In step S1, the alkaline conditioner includes one or more of quicklime and slaked lime.

6. A preparation system for a phosphorus tailings modified green backfill material, which is used to implement the preparation method of the phosphorus tailings modified green backfill material according to any one of claims 1-5, and is characterized in that, The preparation system for the modified green backfill material for phosphorus tailings 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 incoming material pipe from the concentrator, and an alkaline conditioner adding machine, and the feed ports of the mixer are respectively communicated with the discharge port of the phosphorus tailings incoming material pipe from the concentrator and the discharge port of the alkaline conditioner adding machine; The concentrated paste preparation unit includes a thickener unit and a flocculant adding machine, the thickener unit includes at least two paste storage thickeners, and the feed ports of each paste storage thickener are respectively communicated with the discharge port of the mixer and the discharge port of the flocculant adding machine; The green backfill material preparation unit includes a high-speed flexible mixer, a curing agent adding machine, and a compound activator adding machine, and the feed port of the high-speed flexible mixer is respectively communicated with the discharge port of the curing agent adding machine and the discharge port of the compound activator adding machine; The alkaline conditioner discharged by the alkaline conditioner adding machine and the phosphorus tailings mortar discharged by the phosphorus tailings incoming material pipe from the concentrator are prepared into the modified slurry in the mixer; the modified slurry discharged by the mixer and the flocculant discharged by the flocculant adding machine are prepared into a concentrated paste with a bleeding rate ≤ 1% in the thickener unit; the concentrated paste discharged by the thickener unit, the curing agent discharged by the curing agent adding machine, and the compound activator discharged by the compound activator adding machine are prepared into the modified green backfill material for phosphorus tailings in the high-speed flexible mixer.

7. The phosphorus tailings modified green backfill material preparation system according to claim 6, characterized in that, The paste storage thickener includes: A storage body; A slurry-making component, which is arranged in the storage body and is used for aerating and loosening the tailings at the end of the middle plate in the storage body; Conical bin bottom, the conical bin bottom is arranged on the horizontal bin bottom of the paste storage thickener, the outer expanding end of the conical bin bottom is hermetically connected to the inner wall of the bin body, its shrinking end abuts on the horizontal bin bottom, and a sand discharge port is provided at the shrinking end of the conical bin bottom, and the sand discharge port of the conical bin bottom is hermetically connected to the sand discharge port of the horizontal bin bottom.

8. The preparation system of the modified green backfill material with phosphorous tailings according to claim 7, characterized in that, A stepped drainage system is provided at the top of the bin body.

9. The phosphorus tailings modified green backfill material preparation system according to claim 6, characterized in that, Concentration meters and flow meters are provided at the discharge port ends of the alkaline conditioner adding machine, the flocculant adding machine, the paste storage thickener, the curing agent adding machine, and the composite activator adding machine.

10. The phosphorus tailings modified green backfill material preparation system according to claim 6, characterized in that, A buffer hopper is provided at the discharge port end of the high-speed flexible mixer.

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