Method for recycling rare earth mine slag

Abstract

The invention provides a method for recycling rare earth mine slag, which comprises the following steps: (1) mixing the rare earth mine slag with alkali liquor, carrying out one-step dissolution treatment, and carrying out solid-liquid separation treatment on the obtained material to obtain an aluminate solution and rare earth enriched slag; (2) carrying out impurity removal treatment on the aluminate solution to obtain a purified aluminate solution, and carrying out neutralization treatment on the purified aluminate solution to obtain pseudo-boehmite; (3) mixing the rare earth enriched slag with an acid solution, and carrying out two-step dissolution treatment to obtain a rare earth enriched solution and aluminum-silicon slag; wherein the rare earth mine slag in the step (1) comprises aluminum oxide, silicon oxide, rare earth oxide and radioactive elements. According to the method, high-value utilization of aluminum resources in the rare earth mine slag, recovery of rare earth elements and emission reduction of radioactive elements in the rare earth mine slag are achieved, the method can be used for solving the problems that the existing rare earth mine slag is large in stacking amount and difficult to dispose, and good economic and environmental benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource recovery and relates to a method for recovering and reusing rare earth mine slag. Background Art

[0002] The current ionic rare earth ore extraction process includes leaching, hydrolysis precipitation and impurity removal, oxalic acid precipitation of rare earth, roasting and other steps. The hydrolysis precipitation and iron and aluminum removal step produces a large amount of rare earth waste slag, which contains about 40-55% Al2O3, 1% rare earth oxides and 0.01% radioactive elements such as uranium and thorium. Therefore, it is urgent to develop resource recovery and utilization technology for low-radioactive rare earth waste slag.

[0003] CN104498739A discloses a method for separating and recovering uranium, thorium and rare earth from the residue of rare earth ore decomposition, and the method comprises the following steps: acid leaching, filter pressing, anion resin adsorption recovery of uranium, and cationic resin separation and recovery of thorium and rare earth, and finally obtaining heavy oleate, thorium nitrate and rare earth carbonate products. However, the method adopts direct acid leaching, and the rare earth, uranium and thorium elements are not enriched, resulting in low rare earth, uranium and thorium content in the leachate and impurity element content, and low extraction and separation efficiency.

[0004] CN117721301A discloses a method for recycling rare earth, thorium and iron from thorium slag, wherein the thorium slag is mixed with carbon powder and then roasted at high temperature, and then fluorine and aluminum are removed by alkaline leaching, and the alkaline leached slag is successively subjected to acid dissolution, impurity removal, extraction and separation to recover rare earth and thorium elements. However, the method requires high-temperature calcination, high energy consumption, and aluminum resources are not recycled.

[0005] CN116497242A discloses a method for recovering uranium and aluminum from ionic rare earth ore impurity removal residues, wherein the impurity removal residues are acid-dissolved, an ammonium reagent is added to react with aluminum and ammonium to precipitate aluminum into ammonium aluminum sulfate, and then the uranium in the precipitate mother liquor is extracted and separated. However, the method consumes a large amount of concentrated sulfuric acid, and the obtained acid leaching solution has a low pH and a high content of impurity elements, resulting in poor efficiency of subsequent element selective separation; in addition, the price of the produced ammonium aluminum sulfate product is low, which cannot balance the processing cost.

[0006] Therefore, in view of the shortcomings of the existing technology, it is necessary to provide a method that can achieve high-value utilization of aluminum resources in rare earth slag, rare earth recovery and emission reduction of uranium and thorium radioactive elements. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recycling and reusing rare earth mine slag. The method of the present invention realizes the high-value utilization of aluminum resources in rare earth mine slag, the recovery of rare earth elements and the reduction of radioactive elements in rare earth mine slag. It can be used to solve the current problem of large stockpiles and difficult disposal of rare earth mine slag, and has good economic and environmental benefits.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for recycling rare earth mine slag, the method comprising the following steps:

[0010] (1) mixing rare earth mine slag with alkali solution for one-step dissolution treatment, and performing solid-liquid separation treatment on the obtained material to obtain an aluminate solution and rare earth-enriched slag;

[0011] (2) removing impurities from the aluminate solution to obtain a purified aluminate solution, and neutralizing the purified sodium aluminate solution to obtain pseudo-boehmite;

[0012] (3) mixing the rare earth-enriched slag with an acid solution and performing a two-step dissolution treatment to obtain a rare earth-enriched solution and aluminum-silicon slag;

[0013] Wherein, the rare earth mine slag in step (1) comprises aluminum oxide, silicon oxide, rare earth oxides and radioactive elements.

[0014] In the present invention, there is no specific restriction on the composition of the rare earth mine slag, and any rare earth slag containing aluminum, rare earth, silicon, uranium, thorium and other elements can be used in the present invention. The present invention does not limit the operation order of step (2) and step (3), and step (2) can be performed first, or step (3) can be performed first.

[0015] When the rare earth mine slag of the present invention contains radioactive elements such as uranium and thorium, the obtained rare earth enriched liquid also contains radioactive elements such as uranium and thorium, and the radioactive elements such as uranium and thorium will not cause loss.

[0016] The invention is based on the difference in dissolution of aluminum and other metal elements (including rare earth elements, uranium, thorium and other radioactive elements) in rare earth mine slag in a strong alkaline medium. The invention firstly realizes the leaching of aluminum components in a strong alkaline medium, and then leaches rare earth and radioactive elements through an acidic solution. The acidic solution can be returned to leach rare earth concentrate, thereby realizing the high-value utilization of aluminum resources in rare earth mine slag and the effective recycling of rare earth elements, radioactive elements and the like. The method realizes the comprehensive recycling of rare earth mine slag through a green and sustainable recycling process, reduces the pollution of radioactive elements, can be used to solve the problem of large stockpiles and difficult disposal of rare earth slag produced by the current rare earth industry, and has good economic and environmental benefits.

[0017] Preferably, the rare earth oxides in the rare earth mine slag in step (1) include any one of praseodymium oxide, neodymium oxide, yttrium oxide, lanthanum oxide, cerium oxide, gadolinium oxide or dysprosium oxide, or a combination of at least two thereof.

[0018] Preferably, the radioactive elements in the rare earth mine slag in step (1) include uranium and / or thorium.

[0019] Preferably, the rare earth mine slag in step (1) also includes sulfur trioxide.

[0020] Preferably, the alkali solution in step (1) comprises sodium hydroxide solution and / or potassium hydroxide solution, preferably sodium hydroxide solution.

[0021] Preferably, the mass concentration of the alkali solution in step (1) is 50 g / L to 300 g / L, for example, 50 g / L, 100 g / L, 150 g / L, 200 g / L or 300 g / L, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 80 g / L to 200 g / L.

[0022] Preferably, the liquid-to-solid mass ratio of the alkali solution to the rare earth mine slag in step (1) is (1-30):1, for example: 1:1, 5:1, 10:1, 20:1 or 30:1, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably (3-10):1.

[0023] Preferably, the temperature of the one-step dissolution treatment in step (1) is 50°C to 95°C, for example, 50°C, 60°C, 70°C, 80°C or 95°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 70°C to 95°C.

[0024] Preferably, stirring is performed during the one-step dissolution treatment in step (1).

[0025] Preferably, the stirring speed of the one-step dissolution treatment in step (1) is 30rpm to 1000rpm, for example: 30rpm, 50rpm, 100rpm, 500rpm or 1000rpm, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 200rpm to 600rpm.

[0026] Preferably, the time for the one-step dissolution treatment in step (1) is 30 min to 360 min, for example, 30 min, 80 min, 120 min, 240 min or 360 min, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 30 min to 180 min.

[0027] Preferably, the impurity remover in the impurity removal treatment in step (2) comprises an alkaline earth metal compound.

[0028] Preferably, the alkaline earth metal compound comprises any one of calcium oxide, magnesium oxide, calcium hydroxide or magnesium hydroxide, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of calcium oxide and magnesium hydroxide, a combination of calcium hydroxide and magnesium hydroxide, or a combination of calcium oxide and magnesium oxide, etc., preferably calcium oxide and / or calcium hydroxide.

[0029] Preferably, during the impurity removal treatment in step (2), the mass volume ratio of the alkaline earth metal compound to the aluminate solution is 5 g / L to 40 g / L, for example: 5 g / L, 10 g / L, 20 g / L, 30 g / L or 40 g / L, etc., preferably 5 g / L to 20 g / L.

[0030] Preferably, the temperature of the impurity removal treatment in step (2) is 50°C to 95°C, for example, 50°C, 60°C, 70°C, 80°C or 95°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 70°C to 95°C.

[0031] Preferably, the time for the impurity removal treatment in step (2) is 30 min to 300 min, for example: 30 min, 50 min, 100 min, 200 min or 300 min, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 30 min to 150 min.

[0032] The impurity removal treatment of the present invention can remove impurities such as silicon and fluorine in the sodium aluminate solution, thereby obtaining a purified sodium aluminate solution.

[0033] Preferably, the neutralizing agent in the neutralization treatment in step (2) comprises sulfuric acid.

[0034] Preferably, the mass concentration of the sulfuric acid is 10% to 50%, for example, 10%, 20%, 30%, 40% or 50%, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable, preferably 10% to 30%.

[0035] Preferably, stirring is performed during the neutralization treatment in step (2).

[0036] Preferably, the temperature of the neutralization treatment in step (2) is 50°C to 95°C, for example, 50°C, 60°C, 70°C, 80°C or 95°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 70°C to 90°C.

[0037] Preferably, the neutralization treatment time in step (2) is 10 min to 240 min, for example, 10 min, 50 min, 120 min, 180 min or 240 min, etc., not limited to the listed values, other values ​​not listed within the numerical range are also applicable, preferably 10 min to 120 min.

[0038] Preferably, the acid solution in step (3) comprises hydrochloric acid.

[0039] Preferably, the mass concentration of the acid solution in step (3) is 5% to 25%, for example, 5%, 8%, 10%, 15% or 25%, etc., not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 10% to 20%.

[0040] Preferably, the liquid-to-solid mass ratio of the acid solution to the rare earth-enriched slag in step (3) is (1-30):1, for example: 1:1, 5:1, 10:1, 20:1 or 30:1, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably (3-10):1.

[0041] Preferably, the temperature of the two-step dissolution treatment in step (3) is 50°C to 95°C, for example, 50°C, 60°C, 70°C, 80°C or 95°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 70°C to 95°C.

[0042] Preferably, stirring is performed during the two-step dissolution treatment in step (3).

[0043] Preferably, the stirring speed of the two-step dissolution treatment in step (3) is 30rpm to 1000rpm, for example: 30rpm, 50rpm, 100rpm, 500rpm or 1000rpm, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 200rpm to 600rpm.

[0044] Preferably, the time for the two-step dissolution treatment in step (3) is 30 min to 360 min, for example: 30 min, 80 min, 120 min, 240 min or 360 min, etc., not limited to the listed values, other unlisted values ​​within the numerical range are also applicable, preferably 30 min to 180 min.

[0045] As a preferred embodiment of the present invention, the method comprises the following steps:

[0046] (1) mixing rare earth mine slag with an alkali solution having a mass concentration of 80 g / L to 200 g / L at a liquid-solid mass ratio of (3 to 10):1, stirring at 70° C. to 95° C. for a one-step dissolution treatment for 30 min to 180 min, and performing solid-liquid separation treatment to obtain an aluminate solution and rare earth-enriched slag;

[0047] (2) mixing an alkaline earth metal compound with an aluminate solution at a mass volume ratio of 5 g / L to 20 g / L, performing a decontamination treatment at 70° C. to 95° C. to obtain a purified aluminate solution, and then neutralizing the purified aluminate solution with sulfuric acid having a mass concentration of 10% to 30% at 70° C. to 90° C. for 10 min to 120 min to obtain pseudo-boehmite;

[0048] (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 10% to 20% at a liquid-to-solid mass ratio of (3 to 10):1, and subjected to a two-step dissolution treatment at 70°C to 95°C for 30min to 180min to obtain a rare earth enriched liquid and aluminosilicate slag.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The method for recycling and reusing rare earth mine slag described in the present invention can achieve high-value utilization of aluminum resources in rare earth mine slag, effective recovery of rare earth elements and emission reduction of radioactive elements such as uranium and thorium. Through a green and sustainable recycling process, the comprehensive recycling of rare earth mine slag is achieved, reducing the pollution of radioactive elements.

[0051] (2) In the method described in the present invention, the leaching rates of aluminum, rare earth, uranium and thorium reach 90%, 98%, 95% and 96% respectively, and the overall process reduction is greater than 85%. It can be used to solve the problem of large stockpiles and difficult disposal of rare earth waste slag produced by the current rare earth industry, and has good economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a process flow chart for recycling and reusing rare earth mine slag provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] The main components of the rare earth mine slag used in the embodiments of the present invention and the comparative examples are as follows:

[0055] The mass proportion of Al2O3 is 54%, the mass proportion of SO3 is 37%, the mass proportion of SiO2 is 5%, the mass proportion of Fe2O3 is 1%, the mass proportion of rare earths is 1%, the total mass proportion of rare earth elements uranium and thorium is 0.02%, and the mass proportion of other elements such as calcium and potassium is 1.98%.

[0056] Example 1

[0057] This embodiment provides a method for recycling rare earth mine slag, and the process flow diagram of the method is as follows: Figure 1 As shown, the method comprises the following steps:

[0058] (1) mixing rare earth mine slag with a sodium hydroxide solution having a mass concentration of 150 g / L at a liquid-solid mass ratio of 8:1, stirring at a speed of 400 rpm and at 80° C. for a one-step dissolution treatment for 120 min, and performing solid-liquid separation treatment to obtain a sodium aluminate solution and rare earth-enriched slag;

[0059] (2) mixing calcium oxide and sodium aluminate solution at a mass volume ratio of 15 g / L, performing a decontamination treatment at 80° C. for 120 min to obtain a purified sodium aluminate solution, and then neutralizing the purified sodium aluminate solution with 30% sulfuric acid at 75° C. for 90 min to obtain pseudo-boehmite;

[0060] (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 20% at a liquid-solid mass ratio of 5:1, and subjected to a two-step leaching treatment at 80° C. for 120 min to obtain a rare earth enriched solution containing uranium and thorium and aluminosilicate slag; the obtained rare earth enriched solution can be used to leach rare earth concentrate.

[0061] Example 2

[0062] This embodiment provides a method for recycling rare earth mine slag, and the process flow diagram of the method is as follows: Figure 1 As shown, the method comprises the following steps:

[0063] (1) mixing rare earth mine slag with a sodium hydroxide solution having a mass concentration of 200 g / L at a liquid-solid mass ratio of 10:1, stirring at a speed of 600 rpm and at 95° C. for a one-step dissolution treatment for 180 min, and performing solid-liquid separation treatment to obtain a sodium aluminate solution and rare earth-enriched slag;

[0064] (2) mixing magnesium oxide and sodium aluminate solution at a mass volume ratio of 20 g / L, performing a decontamination treatment at 90° C. for 150 min to obtain a purified sodium aluminate solution, and then neutralizing the purified sodium aluminate solution with 20% sulfuric acid at 90° C. for 60 min to obtain pseudo-boehmite;

[0065] (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 15% at a liquid-solid mass ratio of 10:1, and subjected to a two-step leaching treatment at 90° C. for 180 min to obtain a rare earth enriched solution containing uranium and thorium and aluminosilicate slag; the obtained rare earth enriched solution can be used to leach rare earth concentrate.

[0066] Example 3

[0067] This embodiment provides a method for recycling rare earth mine slag, and the process flow diagram of the method is as follows: Figure 1 As shown, the method comprises the following steps:

[0068] (1) mixing rare earth mine slag with a sodium hydroxide solution having a mass concentration of 100 g / L at a liquid-solid mass ratio of 5:1, stirring at a speed of 300 rpm and at 70° C. for a one-step dissolution treatment for 60 min, and performing solid-liquid separation treatment to obtain a sodium aluminate solution and rare earth-enriched slag;

[0069] (2) mixing calcium oxide and sodium aluminate solution at a mass volume ratio of 5 g / L, performing a decontamination treatment at 70° C. for 90 min to obtain a purified sodium aluminate solution, and then neutralizing the purified sodium aluminate solution with 10% sulfuric acid at 70° C. for 30 min to obtain pseudo-boehmite;

[0070] (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 10% at a liquid-solid mass ratio of 8:1, and subjected to a two-step leaching treatment at 75° C. for 90 min to obtain a rare earth enriched solution containing uranium and thorium and aluminosilicate slag; the obtained rare earth enriched solution can be used to leach rare earth concentrate.

[0071] Example 4

[0072] This embodiment provides a method for recycling rare earth mine slag, and the process flow diagram of the method is as follows: Figure 1 As shown, the method comprises the following steps:

[0073] (1) mixing rare earth mine slag with a sodium hydroxide solution having a mass concentration of 120 g / L at a liquid-solid mass ratio of 3:1, stirring at a speed of 600 rpm and at 60° C. for a one-step dissolution treatment for 120 min, and performing solid-liquid separation treatment to obtain a sodium aluminate solution and rare earth-enriched slag;

[0074] (2) mixing calcium oxide and sodium aluminate solution at a mass volume ratio of 10 g / L, performing a decontamination treatment at 60° C. for 60 min to obtain a purified sodium aluminate solution, and then neutralizing the purified sodium aluminate solution with 25% sulfuric acid at 65° C. for 40 min to obtain pseudo-boehmite;

[0075] (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 25% at a liquid-solid mass ratio of 3:1, and subjected to a two-step leaching treatment at 60° C. for 60 min to obtain a rare earth enriched solution containing uranium and thorium and aluminosilicate slag; the obtained rare earth enriched solution can be used to leach rare earth concentrate.

[0076] Example 5

[0077] The only difference between this embodiment and embodiment 1 is that the concentration of the sodium hydroxide solution used for the one-step dissolution in step (1) is 50 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0078] Example 6

[0079] The difference between this embodiment and embodiment 1 is that the concentration of the sodium hydroxide solution used for the one-step dissolution in step (1) is 300 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0080] Example 7

[0081] The only difference between this embodiment and embodiment 1 is that the temperature of the one-step dissolution in step (1) is 50° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0082] Example 8

[0083] The only difference between this embodiment and embodiment 1 is that the temperature of the one-step dissolution in step (1) is 100° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0084] Example 9

[0085] The only difference between this embodiment and embodiment 1 is that the liquid-to-solid mass ratio of the one-step dissolution in step (1) is 2:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0086] Example 10

[0087] The only difference between this embodiment and embodiment 1 is that the liquid-to-solid mass ratio of the one-step dissolution in step (1) is 15:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0088] Embodiment 11

[0089] The only difference between this embodiment and embodiment 1 is that the amount of calcium oxide added in the impurity removal treatment in step (2) is 3 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0090] Example 12

[0091] The only difference between this embodiment and embodiment 1 is that the amount of calcium oxide added in the impurity removal treatment in step (2) is 25 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0092] Example 13

[0093] The only difference between this embodiment and embodiment 1 is that the temperature of the impurity removal treatment in step (2) is 50° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0094] Embodiment 14

[0095] The only difference between this embodiment and embodiment 1 is that the temperature of the impurity removal treatment in step (2) is 100° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0096] Embodiment 15

[0097] The only difference between this embodiment and embodiment 1 is that the concentration of hydrochloric acid used in the second dissolution step (3) is 5%, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0098] Example 16

[0099] The only difference between this embodiment and embodiment 1 is that the concentration of hydrochloric acid used in the second-step dissolution in step (3) is 30%, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0100] Embodiment 17

[0101] The only difference between this embodiment and embodiment 1 is that the temperature of the second dissolution step (3) is 50° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0102] Embodiment 18

[0103] The only difference between this embodiment and embodiment 1 is that the temperature of the second dissolution step in step (3) is 100° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0104] Embodiment 19

[0105] The only difference between this embodiment and embodiment 1 is that the liquid-to-solid mass ratio of the two-step dissolution in step (3) is 2:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0106] Embodiment 20

[0107] The only difference between this embodiment and embodiment 1 is that the liquid-to-solid mass ratio of the two-step dissolution in step (3) is 15:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0108] Performance Test:

[0109] The removal efficiency of silicon and fluorine in the impurity removal treatment was calculated by testing the content of silicon and fluorine in the sodium aluminate solution before and after impurity removal according to the method described in each embodiment. The leaching rate of aluminum was calculated by testing the content of aluminum in the rare earth mine slag and the sodium aluminate solution. The leaching rate of rare earth, uranium and thorium was calculated by testing the content of rare earth, uranium and thorium in the rare earth enriched slag and the rare earth enriched solution. The test results are shown in Table 1:

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, from Examples 1-4, the silicon removal efficiency of the method of the present invention can reach more than 85.7%, the fluorine removal efficiency can reach more than 75.7%, the aluminum leaching efficiency can reach more than 72.3%, the rare earth leaching efficiency can reach more than 83.4%, the radioactive metal uranium leaching efficiency can reach more than 72.9%, and the thorium leaching efficiency can reach more than 78.3%. By adjusting the specific conditions in the recovery process, the silicon removal efficiency of the method of the present invention can reach more than 97.4%, the fluorine removal efficiency can reach more than 94.6%, the aluminum leaching efficiency can reach more than 91.2%, the rare earth leaching efficiency can reach more than 98.5%, the radioactive metal uranium leaching efficiency can reach more than 92.4%, and the thorium leaching efficiency can reach more than 92.8%.

[0114] By comparing Example 1 with Examples 5-6, it can be seen that in the process of recycling and reusing rare earth mine slag according to the present invention, the concentration of the alkali solution used in the one-step dissolution will affect the aluminum leaching effect. The leaching effect is better when the concentration of the alkali solution used in the one-step dissolution is controlled at 80g / L to 200g / L. When the concentration of the alkali solution in the one-step dissolution process is too low, the aluminum leaching rate in the rare earth mine slag is reduced. Increasing the concentration can significantly increase the aluminum leaching efficiency, but too high a concentration of the alkali solution will seriously corrode the equipment.

[0115] By comparing Example 1 with Examples 7-8, it can be seen that in the process of rare earth mine slag recovery and reuse according to the present invention, the temperature of the one-step dissolution will affect the aluminum leaching effect. When the temperature of the one-step dissolution is controlled at 70°C to 95°C, the leaching effect is better. The aluminum leaching efficiency increases with increasing temperature. This is because increasing the temperature can accelerate the reaction rate, thereby increasing the aluminum leaching efficiency. However, too high or too low a temperature will have an adverse effect on the leaching efficiency.

[0116] By comparing Example 1 with Examples 9-10, it can be seen that in the process of recycling and reusing rare earth mine slag described in the present invention, the liquid-to-solid mass ratio of the one-step dissolution will affect the aluminum leaching effect. The liquid-to-solid mass ratio of the one-step dissolution is controlled at 3 to 10:1, and the leaching effect is better. If the liquid-to-solid mass ratio is too low, the concentration of aluminum in the solution is high, which is not conducive to the balance moving in the leaching direction, resulting in a low aluminum leaching rate; if the liquid-to-solid mass ratio is relatively high, it is more conducive to the balance moving in the leaching direction, so that the aluminum leaching rate increases, but further increasing the liquid-to-solid mass ratio will cause waste of raw materials.

[0117] By comparing Example 1 with Examples 11-14, it can be seen that in the process of recycling and reusing rare earth mine slag described in the present invention, the amount of alkaline earth metal compounds added in the impurity removal treatment and the impurity removal temperature will affect the removal effect of silicon and fluorine. The addition amount of alkaline earth metal compounds is controlled at 5g / L~20g / L, and the temperature is controlled at 70°C~95°C. The impurity removal effect is better, the concentration of alkaline earth metal compounds increases, and the reaction temperature increases, which is beneficial to the removal of impurities silicon and fluorine. However, too high a concentration will not achieve better results and will affect subsequent leaching.

[0118] By comparing Example 1 with Examples 15-20, it can be seen that the leaching rates of rare earth, uranium and thorium increase with the increase of hydrochloric acid concentration. In addition, increasing the liquid-solid mass ratio and increasing the temperature can increase the leaching rates of rare earth, uranium and thorium. This is because increasing the liquid-solid mass ratio and increasing the temperature can make the reaction of rare earth, uranium, thorium and hydrochloric acid proceed in the positive reaction direction. However, if the hydrochloric acid concentration, liquid-solid mass ratio and temperature exceed the specified range, it will have an adverse effect on the leaching rate of rare earth, uranium and thorium or the equipment, and it is necessary to control each parameter within a reasonable range.

[0119] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for recycling rare earth mine slag, characterized in that: The method comprises the following steps: (1) mixing rare earth mine slag with alkali solution for one-step dissolution treatment, and performing solid-liquid separation treatment on the obtained material to obtain an aluminate solution and rare earth-enriched slag; (2) removing impurities from the aluminate solution to obtain a purified aluminate solution, and neutralizing the purified sodium aluminate solution to obtain pseudo-boehmite; (3) mixing the rare earth-enriched slag with an acid solution and performing a two-step dissolution treatment to obtain a rare earth-enriched solution and aluminum-silicon slag; Wherein, the rare earth mine slag in step (1) comprises aluminum oxide, silicon oxide, rare earth oxides and radioactive elements.

2. The method according to claim 1, characterized in that The rare earth oxides in the rare earth mine slag in step (1) include any one of praseodymium oxide, neodymium oxide, yttrium oxide, lanthanum oxide, cerium oxide, gadolinium oxide or dysprosium oxide, or a combination of at least two thereof; Preferably, the radioactive elements in the rare earth mine slag in step (1) include uranium and / or thorium; Preferably, the rare earth mine slag in step (1) further comprises sulfur trioxide; Preferably, the alkali solution in step (1) comprises sodium hydroxide solution and / or potassium hydroxide solution, preferably sodium hydroxide solution; Preferably, the mass concentration of the alkali solution in step (1) is 50 g / L to 300 g / L, preferably 80 g / L to 200 g / L.

3. The method according to claim 1 or 2, characterized in that In step (1), the liquid-to-solid mass ratio of the alkali solution to the rare earth mine slag is (1-30):1, preferably (3-10):

1.

4. The method according to any one of claims 1 to 3, characterized in that: The temperature of the one-step dissolution treatment in step (1) is 50°C to 95°C, preferably 70°C to 95°C; Preferably, stirring is performed during the one-step dissolution treatment in step (1); Preferably, the stirring speed of the one-step dissolution treatment in step (1) is 30 rpm to 1000 rpm, preferably 200 rpm to 600 rpm; Preferably, the time for the one-step dissolution treatment in step (1) is 30 min to 360 min, preferably 30 min to 180 min.

5. The method according to any one of claims 1 to 4, characterized in that: The impurity remover in the impurity removal treatment in step (2) comprises an alkaline earth metal compound; Preferably, the alkaline earth metal compound comprises any one or a combination of at least two of calcium oxide, magnesium oxide, calcium hydroxide or magnesium hydroxide, preferably calcium oxide and / or calcium hydroxide; Preferably, during the impurity removal treatment in step (2), the mass volume ratio of the alkaline earth metal compound to the aluminate solution is 5 g / L to 40 g / L, preferably 5 g / L to 20 g / L; Preferably, the temperature of the impurity removal treatment in step (2) is 50°C to 95°C, preferably 70°C to 95°C; Preferably, the time for the impurity removal treatment in step (2) is 30 min to 300 min, preferably 30 min to 150 min.

6. The method according to any one of claims 1 to 5, characterized in that: The neutralizing agent for the neutralization treatment in step (2) includes sulfuric acid; Preferably, the mass concentration of the sulfuric acid is 10% to 50%, preferably 10% to 30%; Preferably, stirring is performed during the neutralization treatment in step (2); Preferably, the temperature of the neutralization treatment in step (2) is 50°C to 95°C, preferably 70°C to 90°C; Preferably, the neutralization treatment time in step (2) is 10 min to 240 min, preferably 10 min to 120 min.

7. The method according to any one of claims 1 to 6, characterized in that: The acid solution in step (3) comprises hydrochloric acid; Preferably, the mass concentration of the acid solution in step (3) is 5% to 25%, preferably 10% to 20%.

8. The method according to any one of claims 1 to 7, characterized in that: In step (3), the liquid-to-solid mass ratio of the acid solution to the rare earth-enriched slag is (1-30):1, preferably (3-10):

1.

9. The method according to any one of claims 1 to 8, characterized in that The temperature of the two-step dissolution treatment in step (3) is 50°C to 95°C, preferably 70°C to 95°C; Preferably, stirring is performed during the two-step dissolution treatment in step (3); Preferably, the stirring speed of the two-step dissolution treatment in step (3) is 30 rpm to 1000 rpm, preferably 200 rpm to 600 rpm; Preferably, the time for the two-step dissolution treatment in step (3) is 30 min to 360 min, preferably 30 min to 180 min.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) mixing rare earth mine slag with an alkali solution having a mass concentration of 80 g / L to 200 g / L at a liquid-solid mass ratio of (3 to 10):1, stirring at 70° C. to 95° C. for a one-step dissolution treatment for 30 min to 180 min, and performing solid-liquid separation treatment to obtain an aluminate solution and rare earth-enriched slag; (2) mixing an alkaline earth metal compound with an aluminate solution at a mass volume ratio of 5 g / L to 20 g / L, performing a decontamination treatment at 70° C. to 95° C. to obtain a purified aluminate solution, and then neutralizing the purified aluminate solution with sulfuric acid having a mass concentration of 10% to 30% at 70° C. to 90° C. for 10 min to 120 min to obtain pseudo-boehmite; (3) The rare earth enriched slag is mixed with hydrochloric acid having a mass concentration of 10% to 20% at a liquid-to-solid mass ratio of (3 to 10):1, and subjected to a two-step dissolution treatment at 70°C to 95°C for 30min to 180min to obtain a rare earth enriched liquid and aluminosilicate slag.

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