A method for repairing a site of ion-type rare earth ore magnesium salt leaching mining

Abstract

The present application relates to a kind of ion type rare earth ore magnesium salt leaching mine site repair method, the repair method includes the following steps: (1) using first leaching agent to rare earth tailings after magnesium salt leaching is washed once, obtains first washing tailings;(2) using second leaching agent to the first washing tailings obtained in step (1) is washed twice, obtains second washing tailings, and the second leaching agent is potassium-containing solution;(3) using third leaching agent to the second washing tailings obtained in step (2) is washed three times, obtains third washing tailings.The repair method provided by the present application can quickly realize magnesium salt leaching, slow down soil acidification, solve the problem of calcium-magnesium nutrient ratio imbalance.

Description

[0001] This invention relates to the field of mining area pollution control and soil remediation, specifically to a remediation method for ion-adsorption rare earth magnesium salt leaching sites. Background Technology

[0002] Ionic rare earth minerals are characterized by their complete composition and rich content of medium and heavy rare earth elements essential for high-tech fields such as semiconductors, defense, and aerospace. They are widely recognized as non-renewable mineral resources crucial for the development of emerging industries. While the existing in-situ leaching process using ammonium sulfate leaching followed by ammonium bicarbonate precipitation has enabled the large-scale development and utilization of ultra-low-grade rare earth minerals, it requires large quantities of leaching agents, and a significant amount of these agents remain within the ore body after leaching. These agents are slowly and persistently released into the surrounding environment under the influence of rainwater leaching, causing serious ammonia nitrogen pollution. To remove residual ammonium salts, solidification or topsoil removal methods can be used to remove residual salts from the soil. However, ionic rare earth mines involve a large soil area, making traditional soil remediation technologies ineffective in removing residual ammonium salts. Alternatively, a water rinsing-reverse osmosis membrane purification method can be used to remove excess ammonium salts, but this method is costly, time-consuming, requires large water consumption, and has poor ammonia nitrogen removal efficiency. A combination of various leaching agents can also be used to remove residual ammonia nitrogen, but this method is prohibitively expensive.

[0003] For example, CN112813289A discloses a method for in-situ removal of ammonia nitrogen pollution from ionic rare earth ores using a leaching agent. This method uses one or more of the following as leaching agents: calcium chloride, potassium chloride, sodium chloride, sodium carbonate, potassium carbonate, magnesium sulfate, aluminum sulfate, ferric sulfate, citric acid, saponins, and saponins, to remove residual ammonia nitrogen from abandoned ionic rare earth mines. While this method can achieve a certain level of ammonia nitrogen removal, it is costly. Therefore, to address the ammonia nitrogen pollution problem caused by ammonium sulfate leaching of ionic rare earth ores at its source, it is imperative to conduct research on ammonium-free leaching of ionic rare earth ores.

[0004] Magnesium sulfate leaching is an emerging green leaching technology. Preliminary leaching experiments have shown that the rare earth leaching rate of magnesium sulfate is comparable to that of ammonium sulfate, while the aluminum leaching rate decreases by more than 15%. Furthermore, if magnesium sulfate is obtained by dissolving lightly calcined magnesium powder with industrial sulfuric acid, the cost is reduced by more than 25% compared to ammonium sulfate. Therefore, using magnesium sulfate as a leaching agent for ion-adsorption rare earth ores has significant socio-economic benefits and can completely eliminate ammonia nitrogen pollution. Plant nutrition studies indicate that the optimal ratio of readily available calcium to magnesium nutrients for crop growth is generally between 1 and 20. An imbalance in this ratio will prevent plants from effectively absorbing calcium and magnesium nutrients from the soil. However, experiments show that when using magnesium sulfate to leach ion-adsorption rare earth ores, a large amount of sulfate remains in the ore soil. After washing, the available magnesium content in the tailings reaches over 500 mg / kg. The presence of a large amount of available magnesium can easily lead to antagonistic effects between nutrients, and excessive magnesium ions can affect the absorption of calcium and potassium ions by crops. Excessive application of magnesium can also increase the concentration of the soil solution, leading to root dehydration and plant dieback. In addition, it will lead to a decrease in the sugar content of agricultural products in the mining area, affecting the quality of agricultural products and greatly reducing the storage time of agricultural products. Furthermore, the in-situ leaching process inevitably results in the leakage of leaching agents, which can lead to acidification of the leaching site, all of which may have an impact on the soil and the environment.

[0005] Therefore, for rare earth tailings from leaching plants with high magnesium content, how to quickly, effectively, and cost-efficiently adjust the calcium-magnesium ratio and improve soil pH is a problem that needs to be solved. Summary of the Invention

[0006] To address the above problems, the present invention aims to provide a method for remediating magnesium salt leaching sites of ion-type rare earth minerals. Compared with the prior art, the remediation method provided by the present invention can quickly achieve magnesium salt leaching, slow down soil acidification, and solve the problem of calcium-magnesium nutrient imbalance.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] This invention provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites, the remediation method comprising the following steps:

[0009] (1) The rare earth tailings after magnesium salt leaching were leached once using the first leaching agent to obtain the first leached tailings.

[0010] (2) The first leached tailings obtained in step (1) are leached a second time using a second leaching agent to obtain a second leached tailings. The second leaching agent is a potassium-containing solution.

[0011] (3) The second leached tailings obtained in step (2) are leached three times using a third leaching agent to obtain the third leached tailings.

[0012] The remediation method provided by this invention is designed for the treatment of rare earth tailings with high magnesium content. After magnesium salt leaching, the remaining ions are mostly water-soluble. First, a first leaching agent is used to remove some water-soluble magnesium ions, while simultaneously removing most sulfate ions, thus slowing down soil acidification. Then, a potassium-containing solution is used as a second leaching agent to achieve strong exchange. Taking advantage of the stronger exchange capacity of potassium ions compared to other cations, it can replace the exchangeable magnesium ions remaining in the soil after in-situ leaching of ion-adsorption rare earth magnesium salts, achieving rapid leaching of excess magnesium. Finally, a third leaching agent is used to address the imbalance of calcium and magnesium nutrient ratios in the magnesium salt leaching system, achieving rapid adjustment and partial solidification of calcium and magnesium nutrient content at the leaching site. Through the synergistic effect of one to three leaching processes and in-situ solidification, potassium can be replenished, and the soil calcium-magnesium ratio can be adjusted. Compared to using a single inorganic salt leaching solution, this method has a shorter leaching cycle and lower cost, providing a reference for the remediation of tailings soil from ion-adsorption rare earth mines.

[0013] Preferably, the magnesium salt in step (1) includes magnesium sulfate and / or magnesium chloride.

[0014] Preferably, the content of readily available magnesium ions in the rare earth tailings is 1000-1500 mg / kg, for example, it can be 1000 mg / kg, 1050 mg / kg, 1100 mg / kg, 1150 mg / kg, 1200 mg / kg, 1250 mg / kg, 1300 mg / kg, 1350 mg / kg, 1400 mg / kg, 1450 mg / kg or 1500 mg / kg, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] Preferably, in step (1), the first rinsing agent comprises water.

[0016] Preferably, the liquid-to-solid ratio of the first leaching agent to the rare earth tailings is (0.15-0.45):1m 3 / t, for example, could be 0.15:1m 3 / t、0.2:1m 3 / t、0.25:1m 3 / t、0.3:1m 3 / t、0.35:1m 3 / t、0.4:1m 3 / t or 0.45:1m 3 / t, not limited to the listed values, also applies to other unlisted values ​​within the range.

[0017] Preferably, the pH of the first leaching tailings is 4.5-5.5, for example, it can be 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4 or 5.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, in step (1), the first rinsing also yields a first leachate.

[0019] Preferably, the first leachate is used for ion-type rare earth ore leaching.

[0020] Preferably, the potassium-containing solution in step (2) includes potassium sulfate solution and / or potassium chloride solution.

[0021] Preferably, the concentration of potassium ions in the potassium-containing solution is 0.01-0.03 mol / L, for example, it can be 0.01 mol / L, 0.015 mol / L, 0.02 mol / L, 0.025 mol / L or 0.03 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In this invention, it is preferable to control the concentration of potassium ions in the potassium-containing solution within a specific range, which can achieve rapid leaching of magnesium salts.

[0023] Preferably, the liquid-to-solid ratio of the second leaching agent to the first leaching tailings is (0.14-0.19):1m 3 / t, for example, could be 0.14:1m 3 / t、0.15:1m 3 / t、0.16:1m 3 / t、0.17:1m 3 / t、0.18:1m 3 / t or 0.19:1m 3 / t, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0024] In this invention, it is preferable to control the liquid-solid ratio of the second leaching agent to the first leaching tailings within a specific range, which can minimize the leaching cost of potassium-containing solution.

[0025] Preferably, the pH of the second leaching tailings is 5.6-6.5, for example, it can be 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4 or 6.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the secondary rinsing in step (2) also yields a second leachate.

[0027] Preferably, the second leachate is used for ion-type rare earth ore leaching.

[0028] Preferably, the third rinsing agent in step (3) includes a calcium-containing solution.

[0029] Preferably, the calcium-containing solution includes a calcium chloride solution.

[0030] Preferably, the concentration of calcium ions in the calcium-containing solution is 0.01-0.03 mol / L, for example, it can be 0.01 mol / L, 0.015 mol / L, 0.02 mol / L, 0.025 mol / L or 0.03 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] In this invention, it is preferable to control the concentration of calcium ions in the calcium-containing solution within a specific range, which can effectively control the calcium-magnesium ratio in the soil within a suitable range.

[0032] Preferably, the liquid-to-solid ratio of the third leaching agent to the second leaching tailings is (0.31-1.52):1m 3 / t, for example, could be 0.31:1m 3 / t、0.4:1m 3 / t、0.5:1m 3 / t、0.6:1m 3 / t、0.7:1m 3 / t、0.8:1m 3 / t、0.9:1m 3 / t、1:1m 3 / t、1.1:1m 3 / t、1.2:1m 3 / t、1.4:1m 3 / t or 1.5:1m 3 / t, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0033] In this invention, it is preferable to control the liquid-solid ratio of the third leaching agent to the second leaching tailings within a specific range, which can minimize the leaching cost of calcium-containing solutions.

[0034] Preferably, the pH of the third leaching tailings in step (3) is 5.5-6.0, for example, but not limited to the listed values ​​of 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0, and other unlisted values ​​within the range are also applicable.

[0035] Preferably, the content of available magnesium ions in the third leaching tailings is 200-800 mg / kg, for example, it can be 200 mg / kg, 300 mg / kg, 400 mg / kg, 500 mg / kg, 600 mg / kg, 700 mg / kg or 800 mg / kg, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] Preferably, the content of readily available calcium ions in the third leaching tailings is 1000-2500 mg / kg, for example, it can be 1000 mg / kg, 1200 mg / kg, 1400 mg / kg, 1600 mg / kg, 1800 mg / kg, 2000 mg / kg, 2200 mg / kg or 2500 mg / kg, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the three rinsing steps in step (3) also yield a third leachate.

[0038] Preferably, the third leachate is used for ion-type rare earth ore leaching.

[0039] As a preferred embodiment of the present invention, the repair method includes the following steps:

[0040] (1) Rare earth tailings after leaching with magnesium sulfate and / or magnesium chloride are leached once using water as the first leaching agent to obtain first leached tailings and first leaching solution. The liquid-solid ratio of the first leaching agent to the rare earth tailings is (0.15-0.45):1m 3 / t, the pH of the first leached tailings is 4.5-5.5;

[0041] (2) The first leached tailings obtained in step (1) are leached a second time using a potassium-containing solution as the second leaching agent to obtain a second leached tailings. The potassium-containing solution includes potassium sulfate solution and / or potassium chloride solution, and the concentration of potassium ions in the potassium-containing solution is 0.01-0.03 mol / L. The liquid-to-solid ratio of the second leaching agent to the first leached tailings is (0.14-0.19):1m 3 / t, the pH of the second leaching tailings is 5.6-6.5;

[0042] (3) The second leached tailings obtained in step (2) are leached three times using a calcium-containing solution as the third leaching agent to obtain the third leached tailings. The calcium-containing solution includes a calcium chloride solution, and the concentration of calcium ions in the calcium-containing solution is 0.01-0.03 mol / L. The liquid-to-solid ratio of the third leaching agent to the second leached tailings is (0.31-1.52):1m 3 / t, the pH of the third leaching tailings is 5.5-6.0;

[0043] The first, second, and third leachates are used for ion-adsorption rare earth ore leaching.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The restoration method provided by the present invention is based on the strong exchange effect of potassium ions, which can replace the residual cations in the soil after in-situ leaching of magnesium salts of ion-type rare earth minerals, thereby achieving rapid leaching of magnesium salts and having a high leaching effect on magnesium ions.

[0046] (2) The remediation method provided by the present invention can further precisely adjust the pH of the soil in the leaching area on the basis of removing excess magnesium ions. Under better conditions, the pH of the third leaching tailings is ≥5.5, which can solve the problem of tailings acidification and realize the rapid adjustment and in-situ solidification of the content of nutrients such as calcium and magnesium, and finally achieve a calcium-magnesium ratio suitable for vegetation restoration and soil conditioning. Under better conditions, the calcium-magnesium ratio reaches 1-10.

[0047] (3) The repair method provided by the present invention requires less rinsing water, has a shorter cycle, is simple in process, and is low in cost. Attached Figure Description

[0048] Figure 1 This is a flowchart of the repair method described in Embodiment 1 of the present invention. Detailed Implementation

[0049] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0050] Example 1

[0051] This embodiment uses raw ore from an ion-adsorption rare earth mine in Dingnan, Ganzhou, Jiangxi Province, with a rare earth ion phase grade of 0.08%. A 2% magnesium sulfate solution was used to simulate in-situ leaching to prepare rare earth tailings. The method was as follows: the unleached soil layer was treated with a solution of 1.32 g / cm³. 3 Soil of a specific density was filled into an acrylic column with an inner diameter of 4 cm and a height of 50 cm. A 2% magnesium sulfate solution was then injected into the soil using a peristaltic pump until the rare earth concentration fell below 0.1 g / L, at which point the injection was stopped, yielding rare earth tailings. The rare earth tailings contained a residual available magnesium concentration of 1200 mg / kg, a residual available calcium concentration of 23.8 mg / kg, and a soil pH of 4.2.

[0052] This embodiment provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites, which remediates the rare earth tailings obtained from the above simulation, such as... Figure 1 As shown, the repair method includes the following steps:

[0053] (1) Rare earth tailings after magnesium sulfate leaching were leached once with water as the first leaching agent to obtain the first leached tailings and the first leaching solution. The liquid-solid ratio of water to rare earth tailings was 0.3:1m. 3 / t, the pH of the first leached tailings is 5.1;

[0054] (2) The first leached tailings obtained in step (1) are leached a second time using potassium chloride solution as the second leaching agent to obtain the second leached tailings. The concentration of potassium ions in the potassium chloride solution is 0.03 mol / L, and the liquid-to-solid ratio of the potassium chloride solution to the first leached tailings is 0.17:1m. 3 / t, the pH of the second leaching tailings is 5.7;

[0055] (3) The second leached tailings obtained in step (2) are leached three times using calcium chloride solution as the third leaching agent to obtain the third leached tailings. The concentration of calcium ions in the calcium chloride solution is 0.02 mol / L, and the liquid-to-solid ratio of the calcium chloride solution to the second leached tailings is 0.91:1m. 3 / t, the pH of the third leaching tailings is 5.5;

[0056] The first, second, and third leachates are used for leaching the next ion-type rare earth ore.

[0057] Example 2

[0058] This embodiment provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites, the remediation method comprising the following steps:

[0059] (1) Rare earth tailings after magnesium sulfate leaching were leached once with water as the first leaching agent to obtain the first leached tailings and the first leaching solution. The liquid-solid ratio of water to rare earth tailings was 0.15:1m. 3 / t, the pH of the first leached tailings is 5.1, and the rare earth tailings are the same as in Example 1;

[0060] (2) The first leached tailings obtained in step (1) are leached a second time using potassium chloride solution as the second leaching agent to obtain the second leached tailings. The concentration of potassium ions in the potassium chloride solution is 0.01 mol / L, and the liquid-to-solid ratio of the potassium chloride solution to the first leached tailings is 0.19:1m. 3 / t, the pH of the second leaching tailings is 6;

[0061] (3) The second leached tailings obtained in step (2) are leached three times using calcium chloride solution as the third leaching agent to obtain the third leached tailings. The concentration of calcium ions in the calcium chloride solution is 0.01 mol / L, and the liquid-to-solid ratio of the calcium chloride solution to the second leached tailings is 1.52:1m. 3 / t, the pH of the third leaching tailings is 5.8;

[0062] The first, second, and third leachates are used for leaching the next ion-type rare earth ore.

[0063] Example 3

[0064] This embodiment provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites, the remediation method comprising the following steps:

[0065] (1) Rare earth tailings after magnesium sulfate leaching were leached once with water as the first leaching agent to obtain the first leached tailings and the first leaching solution. The liquid-solid ratio of water to rare earth tailings was 0.45:1m. 3 / t, the pH of the first leached tailings is 5.1, and the rare earth tailings are the same as in Example 1;

[0066] (2) The first leached tailings obtained in step (1) are leached a second time using potassium sulfate solution as the second leaching agent to obtain the second leached tailings. The concentration of potassium ions in the potassium sulfate solution is 0.02 mol / L, and the liquid-to-solid ratio of the potassium sulfate solution to the first leached tailings is 0.14:1m. 3 / t, the pH of the second leaching tailings is 5.7;

[0067] (3) The second leached tailings obtained in step (2) are leached three times using calcium chloride solution as the third leaching agent to obtain the third leached tailings. The concentration of calcium ions in the calcium chloride solution is 0.03 mol / L, and the liquid-to-solid ratio of the calcium chloride solution to the second leached tailings is 0.31:1m. 3 / t, the pH of the third leaching tailings is 5.6;

[0068] The first, second, and third leachates are used for leaching the next ion-type rare earth ore.

[0069] Example 4

[0070] This embodiment provides a remediation method for ion-adsorption rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the liquid-solid ratio of potassium chloride solution to the first leaching tailings is 0.08:1m. 3 / t.

[0071] Example 5

[0072] This embodiment provides a remediation method for ion-adsorption rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the liquid-solid ratio of potassium chloride solution to the first leaching tailings is 0.23:1m. 3 / t.

[0073] Example 6

[0074] This embodiment provides a method for remediating ion-type rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the concentration of calcium ions in the calcium chloride solution is 0.005 mol / L.

[0075] Example 7

[0076] This embodiment provides a method for remediating ion-type rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the concentration of calcium ions in the calcium chloride solution is 0.05 mol / L.

[0077] Example 8

[0078] This embodiment provides a remediation method for ion-adsorption rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the liquid-solid ratio of calcium chloride solution to the second leaching tailings is 0.05:1m. 3 / t.

[0079] Example 9

[0080] This embodiment provides a remediation method for ion-adsorption rare earth magnesium salt leaching sites. The only difference from Embodiment 1 is that the liquid-solid ratio of calcium chloride solution to the second leaching tailings is 2.27:1m. 3 / t.

[0081] Comparative Example 1

[0082] This comparative example provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites. The only difference from Example 1 is that step (2) is omitted, i.e., the first leaching tailings obtained in step (1) are used instead of the second leaching tailings to directly proceed to step (3). Step (3) is replaced by:

[0083] (3) The first leached tailings obtained in step (2) are leached three times using calcium chloride solution as the third leaching agent to obtain the third leached tailings. The concentration of calcium ions in the calcium chloride solution is 0.02 mol / L, and the liquid-to-solid ratio of the calcium chloride solution to the first leached tailings is 0.91:1m. 3 / t.

[0084] Comparative Example 2

[0085] This comparative example provides a method for remediating ion-adsorption rare earth magnesium salt leaching sites. The only difference from Example 1 is that step (2) is omitted, i.e., the first leaching tailings obtained in step (1) are used instead of the second leaching tailings to directly proceed to step (3). Step (3) is replaced by:

[0086] (3) The first leached tailings obtained in step (1) are leached three times using calcium hydroxide solution as the third leaching agent to obtain the third leached tailings. The concentration of calcium ions in the calcium hydroxide solution is 0.02 mol / L, and the liquid-to-solid ratio of the calcium hydroxide solution to the first leached tailings is 0.91:1m. 3 / t.

[0087] Comparative Example 3

[0088] This comparative example provides a method for the remediation of ion-type rare earth magnesium salt leaching sites. The only difference from Example 1 is that the potassium chloride solution in step (2) is replaced with ferrous chloride solution, ensuring that the molar amount of ferrous chloride used is the same as the molar amount of potassium chloride used in Example 1.

[0089] The pH values ​​of the third leaching tailings in Examples 1-9 and Comparative Examples 1-3 were measured using potentiometric method, and the results are shown in Table 1.

[0090] The leaching rates of sulfate and magnesium ions in Examples 1-9 and Comparative Examples 1-3 were determined by ICP-OES, and the results are shown in Table 1.

[0091] The available calcium and magnesium contents in Examples 1-9 and Comparative Examples 1-3 were determined by atomic absorption spectrophotometry, and the calcium-magnesium ratio was calculated. The results are shown in Table 1.

[0092] Table 1

[0093]

[0094] The following points can be observed from the data in Table 1:

[0095] (1) As can be seen from the data of Examples 1-3, under better conditions, the pH value of the third leaching tailings provided by the present invention reaches above 5.5, which solves the problem of tailings acidification. Moreover, the leaching rate of magnesium ions is moderate, which can effectively remove excess magnesium ions and maintain a suitable calcium-magnesium ratio for vegetation restoration and physicochemical regulation, with the calcium-magnesium ratio reaching between 2.5 and 9.1.

[0096] (2) A comparison of Examples 1 and 4-5 shows that the liquid-to-solid ratio of potassium chloride solution to the first leaching tailings in Example 1 is 0.17:1m. 3 / t, compared to 0.08:1m in Examples 4-5. 3 / t and 0.23:1m 3In terms of / t, Examples 4-5 failed to completely solve the problem of soil acidification, and the calcium-magnesium ratio of the soil in Example 5 was too high, reaching 21.8, which was not conducive to vegetation restoration and soil physicochemical function regulation in the mining area. Therefore, it can be seen that the present invention preferably controls the liquid-solid ratio of potassium chloride solution and the first leaching tailings, which can solve the tailings acidification problem while ensuring a suitable calcium-magnesium ratio for vegetation restoration and soil physicochemical regulation.

[0097] (3) A comparison between Examples 1 and Examples 6-9 shows that in Example 1, the concentration of calcium ions in the calcium chloride solution was 0.02 mol / L, and the liquid-to-solid ratio of the calcium chloride solution to the second leaching tailings was 0.91:1m. 3 / t, compared to the calcium ion concentrations of 0.005 mol / L and 0.05 mol / L in Examples 6-7, and compared to the liquid-to-solid ratios of 0.05:1m in Examples 8-9. 3 / t and 2.27:1m 3 In terms of / t, Examples 6-9 not only failed to completely solve the problem of soil acidification, but the calcium-magnesium ratios in Examples 7 and 9 were too low, and the calcium-magnesium ratio in Example 8 was too high. These are all detrimental to vegetation restoration and soil physicochemical regulation in the mining area. Therefore, it can be seen that the present invention preferably controls the concentration of calcium ions in the calcium chloride solution and the liquid-solid ratio between the calcium chloride solution and the second leaching tailings. This can solve the tailings acidification problem while ensuring a suitable calcium-magnesium ratio for vegetation restoration and soil physicochemical regulation.

[0098] (4) From the comparison between Example 1 and Comparative Examples 1-3, it can be seen that Comparative Example 1 does not use potassium-containing solution for rinsing, Comparative Example 2 does not use potassium-containing solution for rinsing but uses alkaline calcium-containing solution for rinsing, and Comparative Example 3 uses iron-containing solution instead of potassium-containing solution. The pH values ​​of the tailings in the third rinsing in Comparative Examples 1-3 are 5, 9.7 and 4.9, respectively, indicating that the soil acidity and alkalinity are unbalanced. Furthermore, the calcium-magnesium ratio in Comparative Examples 2-3 is too low, which is not conducive to the restoration of vegetation in the mining area and the regulation of soil physicochemical functions. It can be seen that the remediation method provided by the present invention can solve the problem of tailings acidification while ensuring a suitable calcium-magnesium ratio for vegetation restoration and soil physicochemical regulation.

[0099] In summary, the remediation method provided by this invention can quickly achieve magnesium salt leaching, slow down soil acidification, and solve the problem of calcium-magnesium nutrient imbalance.

[0100] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for remediating ion-adsorption rare earth magnesium salt leaching sites capable of rapid leaching of excess magnesium, characterized in that, The repair method includes the following steps: (1) The rare earth tailings after magnesium salt leaching are leached once using the first leaching agent to obtain the first leached tailings; (2) The first leached tailings obtained in step (1) are leached a second time using a second leaching agent to obtain a second leached tailings. The second leaching agent is a potassium-containing solution. (3) The second leached tailings obtained in step (2) are leached three times using a third leaching agent to obtain the third leached tailings; The third rinsing agent in step (3) includes a calcium-containing solution; The calcium-containing solution includes a calcium chloride solution; The content of readily available magnesium ions in the rare earth tailings is 1000-1500 mg / kg.

2. The repair method according to claim 1, characterized in that, The magnesium salt in step (1) includes magnesium sulfate and / or magnesium chloride.

3. The repair method according to claim 1, characterized in that, Step (1) The first rinsing agent includes water.

4. The repair method according to claim 1, characterized in that, The liquid-to-solid ratio of the first leaching agent to the rare earth tailings is (0.15-0.45):1m 3 / t.

5. The repair method according to claim 1, characterized in that, The pH of the first leaching tailings is 4.5-5.

5.

6. The repair method according to claim 1, characterized in that, Step (1) The first rinsing also yields a first leachate.

7. The repair method according to claim 6, characterized in that, The first leachate is used for ion-type rare earth ore leaching.

8. The repair method according to claim 1, characterized in that, The potassium-containing solution in step (2) includes potassium sulfate solution and / or potassium chloride solution.

9. The repair method according to claim 1, characterized in that, The concentration of potassium ions in the potassium-containing solution is 0.01-0.03 mol / L.

10. The repair method according to claim 1, characterized in that, The liquid-to-solid ratio of the second leaching agent to the first leaching tailings is (0.14-0.19):1m 3 / t.

11. The repair method according to claim 1, characterized in that, The pH of the second leaching tailings is 5.6-6.

5.

12. The repair method according to claim 1, characterized in that, The second rinsing in step (2) also yields a second leaching solution.

13. The repair method according to claim 12, characterized in that, The second leachate is used for ion-type rare earth ore leaching.

14. The repair method according to claim 1, characterized in that, The concentration of calcium ions in the calcium-containing solution is 0.01-0.03 mol / L.

15. The repair method according to claim 1, characterized in that, The liquid-to-solid ratio of the third leaching agent to the second leaching tailings is (0.31-1.52):1m 3 / t.

16. The repair method according to claim 1, characterized in that, The pH of the third leaching tailings in step (3) is 5.5-6.

0.

17. The repair method according to claim 1, characterized in that, The content of readily available magnesium ions in the third leaching tailings is 200-800 mg / kg.

18. The repair method according to claim 1, characterized in that, The content of readily available calcium ions in the third leaching tailings is 1000-2500 mg / kg.

19. The repair method according to claim 1, characterized in that, The three rinsing steps in step (3) also yield a third leaching solution.

20. The repair method according to claim 19, characterized in that, The third leachate is used for ion-type rare earth ore leaching.

21. The repair method according to any one of claims 1-20, characterized in that, The repair method includes the following steps: (1) Rare earth tailings after leaching with magnesium sulfate and / or magnesium chloride are leached once using water as the first leaching agent to obtain the first leached tailings and the first leaching solution. The liquid-solid ratio of the first leaching agent to the rare earth tailings is (0.15-0.45):1m 3 / t, the pH of the first leached tailings is 4.5-5.5; (2) The first leached tailings obtained in step (1) are leached a second time using a potassium-containing solution as the second leaching agent to obtain a second leached tailings. The potassium-containing solution includes potassium sulfate solution and / or potassium chloride solution, and the concentration of potassium ions in the potassium-containing solution is 0.01-0.03 mol / L. The liquid-solid ratio of the second leaching agent to the first leached tailings is (0.14-0.19):1m 3 / t, the pH of the second leaching tailings is 5.6-6.5; (3) The second leached tailings obtained in step (2) are leached three times using a calcium-containing solution as the third leaching agent to obtain the third leached tailings. The calcium-containing solution includes a calcium chloride solution, and the concentration of calcium ions in the calcium-containing solution is 0.01-0.03 mol / L. The liquid-to-solid ratio of the third leaching agent to the second leached tailings is (0.31-1.52):1m 3 / t, the pH of the third leaching tailings is 5.5-6.0; The first, second, and third leachates are used for ion-adsorption rare earth ore leaching.

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