Method for treating ion-type rare earth tailing residual leaching agent slow-release pollution

Abstract

The application provides a method for treating slow-release pollution of residual leaching agent of ionic rare earth tailings, and relates to the technical field of mine environmental protection treatment. The main residual leaching agent ions in the ionic rare earth tailings after magnesium salt leaching include magnesium ions and sulfate ions. The application uses the original injection and collection liquid system of in-situ leaching of ionic rare earth, and through pre-embedding replaceable solidification agent in the injection hole (well) and the collection liquid lane (hole), the slow-released magnesium ions, sulfate ions and other ions in the tailings after mine closure are effectively adsorbed, intercepted and solidified, and through the water quality monitoring of the water outlet of the collection liquid lane (hole), the pre-embedded agent can be replaced, so that the slow-release pollution of the residual leaching agent of the ionic rare earth tailings after mine closure can be avoided and released to the external environment of the tailings. The application provides a replaceable pre-embedded agent treatment method for slow-release of ionic rare earth tailings, which is simple to operate and can effectively solve the slow-release pollution problem of the residual leaching agent of the ionic rare earth tailings after magnesium salt leaching from the source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine environmental protection treatment, and particularly relates to a method for treating slow-release pollution of ion-type rare earth tailing residual leaching agent. BACKGROUND

[0002] Due to the long-term ammonia-nitrogen pollution caused by the slow release of residual ammonium salt in ion-type rare earth tailings after being leached by the ammonium salt, at present, the magnesium salt in-situ leaching process using magnesium sulfate as a leaching agent is mainly used in the ion-type rare earth mining in Gannan area. However, the process does not solve the problem of a large amount of residual leaching agent in the tailings after ion-type rare earth leaching and long-term slow release. Instead, the process only replaces the ammonium salt by using the higher threshold of magnesium ion discharge. The ion-type rare earth tailings after magnesium salt leaching will still have magnesium ions, sulfate ions and the like gradually released into the surrounding environment under the action of rainwater leaching and other factors, and it is still possible to cause the problem of excessive content of related elements in the soil and surrounding water in the mining area.

[0003] In view of the slow release of the leaching agent remaining in the ion-type rare earth ore tailings after magnesium salt leaching, the mine currently uses a mode of environmental protection bottom processing of water washing + tail water treatment station. After the leaching is completed, a part of the leaching agent ions are washed away with clean water, and the water area affected by the subsequent slow release of the leaching agent ions is continuously monitored. Therefore, a tail water treatment station is arranged downstream of the mine watershed. Through continuous monitoring of the content level of the leaching agent ions in the upstream water area of the mine watershed, an emergency response mechanism for the content of the leaching agent ions exceeding the standard is established. Once it is found that the leaching agent ions in the upstream watershed exceed the standard, the downstream tail water treatment system is started immediately. The contaminated river water is blocked by the downstream river interception dam, and the river water is all pumped into the wastewater treatment tank of the tail water treatment station. The river water is treated by chemical precipitation method to reach the standard before being discharged. Although the treatment mode of the mine can solve the slow release pollution problem of the residual leaching agent in the ion-type rare earth tailings after leaching to a certain extent, on the one hand, the slow release of the leaching agent in the tailings into the surrounding water may have caused adverse effects on the watershed water environment, but the influence range is reduced, and the pollution problem has not been solved from the root; on the other hand, the water quantity to be treated by the watershed sewage treatment is large, and the treatment cost is high. Moreover, relevant studies have shown that the ion-type rare earth tailings after magnesium salt leaching can only wash out the residual water-soluble leaching agent ions in the tailings by using clean water washing, and the residual exchangeable leaching agent ions in the tailings cannot be directly washed out by clean water. After the water-soluble leaching agent ions in the tailings are leached out, under the premise that the mine soil has a certain moisture content, in order to maintain the electrolyte balance of the system, the exchangeable leaching agent ions in the tailings will slowly convert into water-soluble leaching agent ions until the charge on the surface of the mine soil reaches balance. This is the main reason why the residual leaching agent ions in the ion-type rare earth tailings still cause long-term slow release pollution after clean water washing. In order to solve this problem from the source, researchers have proposed a method of using leaching agent to concentrate leaching of the residual leaching agent in the ion-type rare earth tailings after leaching. The principle is to use leaching agent (calcium chloride, sodium chloride, potassium chloride, etc.) to leach the residual water-soluble and exchangeable ions in the ion-type rare earth tailings. Although this process of using leaching agent to concentrate leaching of the residual leaching agent in the ion-type rare earth tailings can further alleviate the problem of residual leaching agent in the tailings after the mine is closed, on the one hand, the water quantity and the amount of leaching agent required for the leaching agent concentration leaching are large, and the liquid-solid ratio is usually more than five times; on the other hand, the large amount of use of leaching agent will also cause new residues of leaching agent in the ion-type rare earth tailings. Therefore, the process is currently mainly in the laboratory test stage.

[0004] In summary, there is still a lack of effective treatment method for the slow release pollution problem of the residual leaching agent in the ion-type rare earth tailings after magnesium salt leaching. SUMMARY

[0005] Therefore, the present application aims to provide a method for treating residual leaching agent slow-release pollution of ion-type rare earth tailings.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0007] The present application provides a method for treating residual leaching agent slow-release pollution of ion-type rare earth tailings, comprising the following steps:

[0008] The first agent and the second agent are pre-embedded in the liquid injection hole (well) and the liquid collection lane (hole) of the ion-type rare earth tailings after magnesium salt leaching, respectively; the liquid injection hole (well) and the liquid collection lane (hole) are the liquid injection hole (well) and the liquid collection lane (hole) of the injection and collection system arranged during the in-situ magnesium salt leaching of the ion-type rare earth tailings, respectively;

[0009] The water quality of the water outlet of the liquid collection lane (hole) is monitored, and when the concentration of sulfate ions in the effluent exceeds the specified standard value, the first agent and the second agent are replaced;

[0010] The composition of the first agent comprises soil and alkaline calcium source, and the mass ratio of the soil to the alkaline calcium source is 1:0.2-1; the composition of the second agent comprises soil, alkaline calcium source, activated carbon and sodium metaaluminate, and the mass ratio of the soil, the alkaline calcium source, the activated carbon and the sodium metaaluminate is (60-90):(3-15):(5-10):(2-15); the mass of the soil in the first agent and the second agent is calculated as dry weight.

[0011] Preferably, the alkaline calcium source in the first agent and the second agent independently comprises calcium hydroxide and / or calcium oxide.

[0012] Preferably, the pre-embedding method of the first agent is as follows: the first agent is packed into a first sleeve container, and the first sleeve container filled with the first agent is filled into the liquid injection hole (well).

[0013] Preferably, the bottom and the periphery of the first sleeve container are provided with water-permeable small holes.

[0014] Preferably, the first sleeve container filled with the first agent is filled into the liquid injection hole (well), the top of the first sleeve container is 1-5 cm lower than the mouth of the liquid injection hole (well), the pore space between the first sleeve container and the liquid injection hole (well) is closed by a water-permeable slope formed by cement, and the water-permeable slope enables water to flow smoothly into the first sleeve container.

[0015] Preferably, the pre-embedding method of the second agent is as follows: the second agent is packed into a second sleeve container, and the second sleeve container filled with the second agent is filled into the liquid collection lane (hole).

[0016] Preferably, the upper half of the second sleeve container is provided with water-permeable small holes.

[0017] Preferably, after the second sleeve container filled with the second medicament is inserted into the liquid collection lane, the outlet of the liquid collection lane is sealed with cement, and a water outlet is reserved at the bottom of the sealing position.

[0018] Preferably, the method for replacing the first medicament and the second medicament is to take out the corresponding sleeve container, replace the medicament in the sleeve container, and then insert it back into the injection hole (well) or the liquid collection lane.

[0019] Preferably, the water outlet of the liquid collection lane is collected by a liquid collection ditch, and then discharged after adjusting the pH with hydrochloric acid.

[0020] The application provides a method for treating the slow-release pollution of residual leaching agent of ion-type rare earth tailings, comprising the following steps: embedding a first medicament and a second medicament in the injection hole (well) and the liquid collection lane of the ion-type rare earth tailings after magnesium salt leaching, respectively; the injection hole (well) and the liquid collection lane are the injection hole (well) and the liquid collection lane in the injection and collection system arranged during the in-situ leaching of the ion-type rare earth ore by magnesium salt; monitoring the water quality of the water outlet of the liquid collection lane, and replacing the first medicament and the second medicament when the concentration of sulfate ions in the water outlet exceeds the specified standard value; the composition of the first medicament comprises soil and alkaline calcium source, and the mass ratio of the soil to the alkaline calcium source is 1:0.2-1; the composition of the second medicament comprises soil, alkaline calcium source, activated carbon and sodium metaaluminate, and the mass ratio of the soil, the alkaline calcium source, the activated carbon and the sodium metaaluminate is (60-90):(3-15):(5-10):(2-15); the mass of the soil in the first medicament and the second medicament is calculated by dry weight. The main residual leaching agent ions in the ion-type rare earth tailings after magnesium salt leaching include magnesium ions and sulfate ions. The application utilizes the original injection and collection system of the in-situ leaching of the ion-type rare earth ore, and embeds replaceable solidified medicaments in the injection hole (well) and the liquid collection lane, so as to effectively adsorb, intercept and solidify the magnesium, sulfate and other ions slowly released from the tailings after the mine is closed, and replace the embedded medicaments through the monitoring of the water quality of the water outlet of the liquid collection lane, so as to avoid the slow-release pollution of the residual leaching agent of the ion-type rare earth tailings after the mine is closed from being released to the external environment of the tailings. The application provides a method for treating the slow-release of ion-type rare earth tailings by replaceable embedded medicaments, which is simple and convenient to operate, and can effectively solve the problem of slow-release pollution of the residual leaching agent of the ion-type rare earth tailings after magnesium salt leaching from the source. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the in-situ leaching process of ion-type rare earth ore. DETAILED DESCRIPTION

[0022] The application provides a method for treating residual leaching agent pollution of ion type rare earth tailings, comprising the following steps:

[0023] The first medicament and the second medicament are pre-embedded in the liquid injection hole (well) and the liquid collection lane (hole) of the ion type rare earth tailings after magnesium salt leaching, wherein the liquid injection hole (well) and the liquid collection lane (hole) are respectively the liquid injection hole (well) and the liquid collection lane (hole) in the liquid injection and collection system arranged during the in-situ leaching of the ion type rare earth ore with magnesium salt;

[0024] The water quality of the outlet of the liquid collection lane (hole) is monitored, and when the concentration of sulfate ions in the outlet water exceeds the specified standard value, the first medicament and the second medicament are replaced;

[0025] The composition of the first medicament comprises soil and alkaline calcium source, and the mass ratio of the soil to the alkaline calcium source is 1:0.2-1; the composition of the second medicament comprises soil, alkaline calcium source, activated carbon and sodium metaaluminate, and the mass ratio of the soil, the alkaline calcium source, the activated carbon and the sodium metaaluminate is (60-90):(3-15):(5-10):(2-15); the mass of the soil in the first medicament and the second medicament is calculated by dry weight.

[0026] The first medicament and the second medicament are pre-embedded in the liquid injection hole (well) and the liquid collection lane (hole) of the ion type rare earth tailings after magnesium salt leaching. In the application, the liquid injection hole (well) and the liquid collection lane (hole) are respectively the liquid injection hole (well) and the liquid collection lane (hole) in the liquid injection and collection system arranged during the in-situ leaching of the ion type rare earth ore with magnesium salt. The application does not have special requirements for the specific arrangement of the liquid injection hole (well) and the liquid collection lane (hole) in the liquid injection and collection system, and the conventional arrangement of the person skilled in the art during the in-situ leaching of the ion type rare earth ore can be used, and reference can be made to the In-situ Leaching Mining Technology Specification for Ion Type Rare Earth Ores (draft for comments). Figure 1 An in-situ leaching process diagram of ion type rare earth ore is given, as shown in Figure 1 The liquid injection hole (well) and the liquid collection lane (hole) are respectively the liquid injection hole (well) and the liquid collection lane (hole) in the liquid injection and collection system arranged during the in-situ leaching of the ion type rare earth ore with magnesium salt. The application does not have special requirements for the specific arrangement of the liquid injection hole (well) and the liquid collection lane (hole) in the liquid injection and collection system, and the conventional arrangement of the person skilled in the art during the in-situ leaching of the ion type rare earth ore can be used, and reference can be made to the In-situ Leaching Mining Technology Specification for Ion Type Rare Earth Ores (draft for comments).

[0027] In the present application, the composition of the first medicament (also referred to as injection system pre-embedded medicament in the present application) comprises soil and alkaline calcium source, the alkaline calcium source preferably comprises calcium hydroxide (quicklime) and / or calcium oxide, and the soil is preferably backfill soil (backfill soil refers to the soil excavated during injection of the liquid receiving lane (hole)); the mass ratio of the soil to the alkaline calcium source is 1:0.2-1, preferably 1:0.25-0.5, and the mass of the soil is calculated by dry weight; the first medicament is mixed uniformly with the components. In the present application, the first medicament has the following effects: 1. adjusting the pH value of the infiltrated rainwater, the rainwater in the southern red soil region is generally weakly acidic, and existing studies have shown that the lower the pH value of the rainwater, the stronger the elution effect of the residual leaching agent ions in the ionic rare earth tailings, the more obvious the slow-release effect, and the greater the impact on the liquid receiving system, which can significantly shorten the service time of the liquid receiving system pre-embedded medicament; 2. affected by the pH value of the magnesium salt leaching agent, the pH value of the soil in the leached ionic rare earth tailings is between 5 and 6, which is weakly acidic, and the infiltrated water after the injection system pre-embedded medicament unit can also regulate the pH value of the soil in the tailings; 3. in order to avoid the impact of infiltrated water with too low pH value on the solidification effect of the liquid receiving system, the optimal pH range for the solidification reaction of the liquid receiving system is 10-11; 4. the infiltrated water after the injection system pre-embedded medicament mainly contains calcium hydroxide, the hydroxyl ions of which can react with the residual magnesium ions in the tailings to form magnesium hydroxide, and the calcium ions can react with the residual sulfate ions in the tailings to form slightly soluble calcium sulfate, which can play a role in preliminary solidification of magnesium ions and sulfate ions, reducing the content of leaching agent ions released from the tailings soil to the liquid receiving system pre-embedded medicament unit.

[0028] In the present application, the pre-embedding method of the first medicament is preferably as follows: the first medicament is packed into a first sleeve container, and the first sleeve container filled with the first medicament is filled into the injection hole (well). In the present application, the first medicament is preferably packed into a nylon cloth bag. In the present application, the material of the first sleeve container is preferably plastic, stainless steel or organic glass, and the size of the first sleeve container is preferably comparable to the size of the injection hole (well); the bottom and the periphery of the first sleeve container are preferably provided with water-permeable small holes. In the present application, the first sleeve container filled with the first medicament is filled into the injection hole (well), the top of the first sleeve container is preferably 1-5 cm lower than the mouth of the injection hole (well), the pore space between the first sleeve container and the injection hole (well) is preferably closed by a water-permeable slope made of cement, the water-permeable slope allows water to flow smoothly into the first sleeve container; the surface of the water-permeable slope is covered with soil and marked.

[0029] In the present application, the composition of the second medicament (also referred to as the pre-embedded medicament of the liquid collection system in the present application) includes soil, an alkaline calcium source, activated carbon and sodium metaaluminate, the alkaline calcium source preferably includes calcium hydroxide and / or calcium oxide, the soil is preferably backfill soil, and the activated carbon is preferably biochar; the mass ratio of the soil, the alkaline calcium source, the activated carbon and the sodium metaaluminate is (60-90):(3-15):(5-10):(2-15), preferably (60-85):(5-15):(5-10):(5-15), and in the embodiments of the present application, specifically 60:15:10:15 or 85:5:5:5, the mass of the soil being calculated on a dry weight basis. In the present application, the second medicament can be mixed uniformly with the components. In the present application, the activated carbon mainly plays a role in adsorption and enhancing the reaction effect; the alkaline calcium source mainly plays a role in increasing the pH value, generating magnesium hydroxide and ettringite precipitates, and playing a role in solidifying magnesium ions and sulfate ions; and the sodium metaaluminate mainly provides aluminum ions required for the reaction of the ettringite precipitates. The ions of the leaching agent mainly remaining in the ionic rare earth tailings after magnesium salt leaching of the tailings include magnesium ions and sulfate ions, the pre-configured medicament is embedded in the liquid collection system in the present application, and the slowly released magnesium ions, sulfate ions and other ions in the ionic rare earth tailings are effectively adsorbed, intercepted and solidified, the magnesium ions generate magnesium hydroxide precipitates which are difficult to dissolve under the action of the alkaline calcium source, the calcium ions and the sulfate ions generate ettringite precipitates which are difficult to dissolve under the action of aluminum ions, and finally the dual effect of solidifying magnesium ions and sulfate ions is achieved (the reactions are shown in formula a and formula b).

[0030] Mg 2+ +2OH - =Mg(OH)2↓Formula a

[0031] 6Ca 2+ +3SO4 2- +2﹝Al(OH)6﹞ 3- (s)+26H2O→Ca6Al2(SO4)3(OH) 12 ·26H2O↓Formula b

[0032] In the present application, the pre-embedding method of the second medicament is preferably: the second medicament is packed into a second sleeve container, and the second sleeve container with the second medicament is filled into a liquid collecting channel (hole). In the present application, the second medicament is preferably packed into a nylon cloth bag; the material of the second sleeve container is preferably the same as the above technical solution, which will not be repeated here; the upper half of the second sleeve container is preferably provided with a water permeable small hole. The liquid collecting channel (hole) is generally horizontally punched into the mountain at the foot of the mountain, and the liquid injection hole (well) is vertically punched into the mountain at the top of the mountain, so the first sleeve container is provided with a water permeable small hole at the bottom and around the first sleeve container to facilitate the outflow of water flowing into the first sleeve container; and the second sleeve container is horizontally inserted into the mountain, mainly serving to collect the water flow in the liquid collecting channel (hole), so a water permeable small hole is provided in the upper half of the second sleeve container. In the present application, after the second sleeve container with the second medicament is filled into the liquid collecting channel (hole), the outlet of the liquid collecting channel (hole) is sealed with cement, and a water outlet is reserved at the bottom of the sealing position for seepage water discharge and water quality monitoring; the water (i.e. seepage water) of the liquid collecting channel (hole) is collected by a liquid collecting ditch and discharged to the surrounding water area after adjusting the pH with hydrochloric acid.

[0033] After the first medicament and the second medicament are respectively pre-embedded in the liquid injection hole (well) and the liquid collecting channel (hole) of the ion type rare earth tailings after magnesium salt leaching of the ore, the present application monitors the water quality of the outlet of the liquid collecting channel (hole), and when the concentration of sulfate ions in the outlet water exceeds the specified standard value, the first medicament and the second medicament are replaced. In the embodiment of the present application, the discharge requirement of sulfate ions in the "Ion Type Rare Earth Mine Exploitation Water Pollutant Discharge Standard" (DB361016-2018) is taken as the standard value. In the present application, the method for replacing the first medicament and the second medicament is preferably: the corresponding sleeve container is taken out, the medicament in the sleeve container is replaced, and then the sleeve container is inserted back into the liquid injection hole (well) or the liquid collecting channel (hole). In the embodiment of the present application, the specific replacement operation steps of the first medicament and the second medicament are: first, break the cement seal, pull out the original sleeve container, adjust the medicament ratio according to the slow-release blocking effect, insert the medicament into the sleeve container, insert the sleeve container with the medicament into the liquid injection hole (well) or the liquid collecting channel (hole), reseal with cement, clean out the medicament in the original medicament sleeve, and dispose according to the requirements, and the sleeve container is recycled; wherein the specific adjustment of the medicament ratio according to the slow-release blocking effect refers to the corresponding adjustment of the medicament ratio according to the water flow of the outlet of the liquid collecting channel (hole) and the concentration of magnesium and sulfate ions in the outlet water. The position with higher water flow and slow-release ion concentration needs to relatively reduce the proportion of soil in the medicament composition and increase the proportion of the remaining medicament composition.

[0034] The application utilizes the injection and collection liquid system of ion type rare earth in-situ leaching mine, through the replaceable pre-embedded solidified reagent, and the pre-embedded reagent of the injection liquid system and the pre-embedded reagent of the collection liquid system which are different in composition and function, the magnesium and sulfate ions slowly released in the tailings after the mine is closed are effectively adsorbed, intercepted and solidified, and the pre-embedded reagent is replaced through the water quality monitoring of the outlet of the collection liquid lane (hole) to avoid the pollution to the external environment. The replaceable pre-embedded reagent treatment method for the slow release of ion type rare earth tailings provided by the application can effectively solve the slow release pollution problem of the residual leaching agent in the ion type rare earth magnesium salt leaching tailings from the source, and the raw materials are easy to obtain, the treatment process is short, the operation is simple, and the treatment cost is low. In addition, the replaceable pre-embedded reagent treatment method for the slow release of ion type rare earth tailings provided by the application will not cause new slow release of reagent in the tailings, because the first reagent is calcium oxide or calcium hydroxide which will become calcium hydroxide solution when meeting water, on the one hand, the solubility of the solution is relatively low, and on the other hand, when meeting magnesium ions and sulfate ions in the ore body, a part of calcium ions will be consumed to form a precipitate, so the residual calcium ions in the tailings will not be too much; on the other hand, after the long-term leaching in the leaching process, the calcium and magnesium ions in the ore body are lost in large amounts, and the calcium and magnesium ions solidified in the ore body can also be used as a calcium and magnesium source.

[0035] The method for treating the slow release pollution of ion type rare earth tailings residual leaching agent provided by the application will be described in detail in combination with the embodiments below, but they cannot be understood as the limitation of the protection scope of the application.

[0036] According to the existing tailings slow release data of the mine area, the slow release concentration of sulfate ions in the ion type rare earth magnesium salt leaching tailings is 1000-5000 mg / L, and the discharge requirement of sulfate ions in Jiangxi Province “Ion Type Rare Earth Mine Exploitation Water Pollutant Discharge Standard” (DB361016-2018) is 800 mg / L. The indoor simulation test is carried out according to this standard as the slow release interception terminal to verify the slow release treatment effect of the replaceable pre-embedded reagent on the ion type rare earth tailings after magnesium salt leaching under different proportioning conditions.

[0037] Example 1

[0038] 1000 g of ion type rare earth ore is loaded into an ion exchange column, and is compacted in steps to prevent channeling, and is leached by 2% wt magnesium sulfate solution until no rare earth is detected in the leaching liquid, and the ion type rare earth tailings after magnesium salt leaching is reserved;

[0039] The soil and slaked lime are mixed uniformly in a mass ratio of 4:1, 100 g of which is loaded into a small ion exchange column to simulate the replaceable pre-embedded reagent of the liquid injection system; the soil, slaked lime, activated carbon and sodium metaaluminate are mixed uniformly in a mass ratio of 85:5:5:5, 200 g of which is loaded into a small ion exchange column to simulate the replaceable pre-embedded reagent of the liquid collection system, and the ion exchange column of the replaceable pre-embedded reagent of the liquid injection system, the ion exchange column of the ion type rare earth tailings and the ion exchange column of the replaceable pre-embedded reagent of the liquid collection system are sequentially placed in order from top to bottom;

[0040] In the test, the rainwater infiltration environment is simulated, and pure water is slowly injected into the ion exchange column of the replaceable pre-embedded reagent of the liquid injection system, and it can be observed that after the soil moisture in the column is adsorbed and saturated, the leaching liquid at the outlet below the exchange column flows into the ion exchange column of the ion type rare earth tailings, and because the tailings in the column are already in a saturated water absorption state, the leaching liquid at the outlet below the exchange column also begins to flow into the ion exchange column of the liquid collection system. The sample is measured, and the concentration of sulfate ions in the leaching liquid is 12000 mg / L. After the soil moisture in the ion exchange column of the liquid collection system is adsorbed and saturated, the leaching liquid begins to flow out of the outlet below the exchange column.

[0041] The test results show that the leaching liquid at the outlet of the liquid injection system ion exchange column is relatively stable, and when the volume of the leaching liquid flowing out reaches 10 L, the pH of the leaching liquid is still stable at above 12. The concentration of sulfate ions in the leaching liquid at the outlet of the ion type rare earth tailings ion exchange column is relatively stable in the early stage, and the pH of the leaching liquid does not change much. Subsequently, as the pH of the leaching liquid gradually rises, the concentration of sulfate ions decreases obviously, but it is still higher than the limit value of 800 mg / L. Then the leaching liquid enters the ion exchange column of the liquid collection system, and when the volume of the leaching liquid at the outlet of the ion exchange column of the liquid collection system reaches 10 L, the concentration of sulfate ions in the leaching liquid is always stable within the standard range of 800 mg / L, and the concentration of magnesium ions is stable at less than 100 mg / L, and the water impact liquid-solid ratio can be more than 50 times. Therefore, it can be seen that the replaceable pre-embedded reagent for liquid injection and collection has good treatment effect on the residual and slow release of magnesium salt leaching reagent for ion type rare earth tailings.

[0042] Example 2

[0043] 1000 g of ion type rare earth tailings is loaded into an ion exchange column, and is compacted in steps to prevent channeling. A 2%wt magnesium sulfate solution is used for leaching until no rare earth is detected in the leaching liquid. The ion type rare earth tailings after magnesium salt leaching is reserved;

[0044] The soil and slaked lime are mixed uniformly according to a mass ratio of 1:1, 100 g of which is loaded into a small ion exchange column to simulate a replaceable embedded reagent of the liquid injection system; the soil, slaked lime, activated carbon and sodium metaaluminate are mixed uniformly according to a mass ratio of 60:15:10:15, 200 g of which is loaded into a small ion exchange column to simulate a replaceable embedded reagent of the liquid collection system, and the ion exchange column of the replaceable embedded reagent of the liquid injection system, the ion exchange column of the ion type rare earth tailings and the ion exchange column of the replaceable embedded reagent of the liquid collection system are sequentially placed in order from top to bottom;

[0045] In the test, a rainwater infiltration environment is simulated, and pure water is slowly injected into the ion exchange column of the replaceable embedded reagent of the liquid injection system, and it can be observed that after the soil moisture in the column is adsorbed and saturated, the leaching liquid at the outlet below the exchange column flows into the ion exchange column of the ion type rare earth tailings, and because the tailings in the column are already in a saturated water absorption state, the leaching liquid at the outlet below the exchange column also begins to flow into the ion exchange column of the liquid collection system, and the concentration of sulfate ions in the leaching liquid is 12000 mg / L, and after the soil moisture in the ion exchange column of the liquid collection system is adsorbed and saturated, the leaching liquid at the outlet below the exchange column begins to flow out;

[0046] The test results show that the leaching liquid at the outlet of the ion exchange column of the liquid injection system is relatively stable, and when the volume of the leaching liquid flowing out reaches 20 L, the pH of the leaching liquid is still stable at above 12; the concentration of sulfate ions in the leaching liquid at the outlet of the ion exchange column of the ion type rare earth tailings is relatively stable in the early stage, and the pH of the leaching liquid does not change much, and then the concentration of sulfate ions decreases obviously as the pH of the leaching liquid gradually rises, but it is still higher than the limit value of 800 mg / L; then the leaching liquid enters the ion exchange column of the liquid collection system, and when the volume of the leaching liquid at the outlet of the ion exchange column of the liquid collection system reaches 20 L, the concentration of sulfate ions in the leaching liquid is always stable within the standard range of 800 mg / L, the concentration of magnesium ions is stable and less than 100 mg / L, and the water impact liquid-solid ratio can be more than 100 times; it can be seen that the replaceable embedded reagent of the liquid injection and collection system has a good treatment effect on the residual and slow release of the magnesium salt leaching agent of the ion type rare earth tailings.

[0047] The above only describes preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A method for treating the slow-release pollution of ion-type rare earth tailings residual lixivium, characterized in that, The method comprises the following steps: First and second reagents are pre-embedded in injection holes and liquid collection tunnels of ion-type rare earth tailings after magnesium salt leaching of ores; the injection holes and liquid collection tunnels are respectively injection holes and liquid collection tunnels in an injection and collection system arranged for ion-type rare earth ore magnesium salt in-situ leaching; Water quality at an outlet of the liquid collection tunnel is monitored, and the first and second reagents are replaced when the concentration of sulfate ions in the outlet water exceeds a specified standard value; The first reagent comprises soil and an alkaline calcium source, and the mass ratio of the soil to the alkaline calcium source is 1:0.2-1; the second reagent comprises soil, an alkaline calcium source, activated carbon and sodium metaaluminate, and the mass ratio of the soil, the alkaline calcium source, the activated carbon and the sodium metaaluminate is (60-90):(3-15):(5-10):(2-15); the soil in the first and second reagents is in dry weight.

2. The method of claim 1, wherein, The alkaline calcium source in the first and second reagents independently comprises calcium hydroxide and / or calcium oxide.

3. The method of claim 1, wherein, The pre-embedding method of the first reagent is to pack the first reagent into a first sleeve container, and then fill the first sleeve container with the first reagent into the injection hole.

4. The method of claim 3, wherein, The bottom and the periphery of the first sleeve container are provided with water-permeable small holes.

5. The method of claim 3, wherein, The first sleeve container with the first reagent is filled into the injection hole, the top of the first sleeve container is 1-5 cm lower than the injection hole, the gap between the first sleeve container and the injection hole is closed by a water-permeable slope formed by cement, and the water-permeable slope allows water to flow smoothly into the first sleeve container.

6. The method of claim 1, wherein, The pre-embedding method of the second reagent is to pack the second reagent into a second sleeve container, and then fill the second sleeve container with the second reagent into the liquid collection tunnel.

7. The method of claim 6, wherein, The upper half of the second sleeve container is provided with water-permeable small holes.

8. The method of claim 6, wherein, After the second sleeve container with the second reagent is filled into the liquid collection tunnel, the outlet of the liquid collection tunnel is sealed with cement, and a water outlet is reserved at the bottom of the sealing position.

9. The method according to claim 3 or 6, characterized in that, The method for replacing the first and second reagents is to take out the corresponding sleeve container, replace the reagent in the sleeve container, and then pack the sleeve container back into the injection hole or the liquid collection tunnel.

10. The method of claim 1, wherein, The outlet water of the liquid collection tunnel is collected by a liquid collecting ditch, and then discharged after pH adjustment by hydrochloric acid.

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