Method for comprehensively recovering valuable components in waste lithium-containing polishing powder

Abstract

The invention relates to a method for comprehensively recovering valuable components in waste lithium-containing polishing powder, which not only can realize the recovery of rare earth in the waste lithium-containing polishing powder, but also can obtain aluminum-containing high-added-value products through a vitriol formation and crystallization method, thereby ensuring higher recovery rate of lithium. The method provided by the invention is simple in process flow and low in recycling cost, realizes high-added-value recycling of the waste lithium-containing polishing powder, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy, and relates to a method for recovering valuable components from solid waste, in particular to a method for comprehensively recovering valuable components in waste lithium-containing polishing powder. Background Art

[0002] With the increasing requirements for the surface quality and polishing accuracy of glass substrates, polishing powder is used in large quantities, and the large-scale application of polishing powder has led to an increasing amount of waste polishing powder generated year by year. The waste polishing powder contains a certain amount of lithium element, and recycling it can reduce resource waste.

[0003] Lithium-containing polishing powder includes lithium aluminosilicate-based polishing powder, rare-earth doped lithium-based polishing powder, and composite lithium-based polishing powder. At present, the main object of recycling waste lithium-containing polishing powder is lithium aluminosilicate-based polishing powder, and the recycling methods include acid leaching roasting using additives. However, the conventional sulfuric acid roasting method is mainly used to recover rare-earth elements in waste lithium-containing polishing powder, and lithium and aluminum therein are not effectively recovered.

[0004] CN118207432A discloses a method for extracting valuable elements from waste polishing powder. First, the waste polishing powder is mixed and roasted with an additive, then leached in a sulfuric acid solution, and the leachate is subjected to stepwise precipitation for impurity removal to produce lanthanum and lithium phosphate products.

[0005] CN112609076A discloses a method for recovering rare-earth oxides from waste rare-earth polishing powder. First, concentrated sulfuric acid is added to the waste rare-earth polishing powder for roasting, then water leaching is carried out, then oxalic acid is added for precipitation, and finally calcination is carried out to obtain rare-earth oxides.

[0006] The recycling methods in the prior art require the use of additives, which increases the recycling cost; or benzoate is needed for the recovery of aluminum, resulting in the generation of organic wastewater and causing high wastewater treatment costs. At the same time, most of the other prior arts use pH adjustment to remove aluminum, resulting in excessive entrainment loss of lithium. In addition, the existing conventional sulfation roasting process for recycling polishing powder is mainly for the recovery of rare-earth oxides and does not involve the recovery of lithium and aluminum.

[0007] Therefore, there is a need to provide a method for comprehensively recovering valuable components in waste lithium-containing polishing powder that can effectively recover lithium, aluminum, and rare-earth elements. Summary of the Invention

[0008] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for comprehensively recovering valuable components from waste lithium-containing polishing powder. The method can not only recover rare earths from waste lithium-containing polishing powder, but also obtain high-value-added aluminum-containing products through alum crystallization, ensuring a relatively high recovery rate of lithium. The process flow of the method provided by the present invention is simple, the recovery cost is low, the high-value-added recycling of waste lithium-containing polishing powder is realized, and it is suitable for large-scale industrial production.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted:

[0010] The present invention provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder, which is characterized in that the method comprises the following steps:

[0011] (1) Acid-leach the waste lithium-containing polishing powder, carry out roasting, and obtain roasted slag and roasting flue gas;

[0012] (2) Water-leach the roasted slag obtained in step (1) to obtain a water-leachate and water-leached slag;

[0013] (3) Adjust the pH value of the water-leachate obtained in step (2) to a first pH value, add a first precipitant for rare earth precipitation treatment, and obtain a post-rare earth precipitation solution and rare earth precipitation slag;

[0014] (4) Mix an aluminum removal agent with the post-rare earth precipitation solution obtained in step (3) for aluminum removal treatment to obtain alum and post-aluminum removal solution;

[0015] (5) Use a second precipitant to adjust the pH value of the post-aluminum removal solution obtained in step (4) to a second pH value for impurity removal treatment to obtain a post-impurity removal solution; after the post-impurity removal solution is subjected to calcium removal treatment, phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0016] The method provided by the present invention can not only recover rare earths from waste lithium-containing polishing powder, but also obtain high-value-added aluminum-containing products through alum crystallization, ensuring a relatively high recovery rate of lithium; moreover, the process flow of the method provided by the present invention is simple, the recovery cost is low, the high-value-added recycling of waste lithium-containing polishing powder is realized, and it is suitable for large-scale industrial production.

[0017] Preferably, the waste lithium-containing polishing powder is waste rare earth-doped lithium-based polishing powder.

[0018] Preferably, the acid leaching in step (1) is carried out using sulfuric acid with a concentration of more than 95 wt%, for example, it can be 95 wt%, 96 wt%, 97 wt% or 98 wt%, but is not limited to the listed values, and the remaining unlisted values within the numerical range are equally applicable.

[0019] Preferably, the mass ratio of sulfuric acid to waste lithium-containing polishing powder is 1.6:1 - 2:1. For example, it can be 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0020] Preferably, for the method provided by the present invention, the roasting flue gas obtained by roasting is absorbed by liquid caustic soda to obtain the by-product sodium fluoride.

[0021] Preferably, the roasting in step (1) includes a first roasting and a second roasting carried out in sequence.

[0022] Preferably, the temperature of the first roasting is 200°C - 250°C, and the time is 1h - 3h.

[0023] The temperature of the first roasting is 200°C - 250°C. For example, it can be 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0024] The time of the first roasting is 1h - 3h. For example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0025] Preferably, the temperature of the second roasting is 300°C - 400°C, and the time is 1h - 3h.

[0026] The temperature of the second roasting is 300°C - 400°C. For example, it can be 300°C, 320°C, 330°C, 350°C, 360°C, 380°C or 400°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0027] The time of the second roasting is 1h - 3h. For example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0028] By carrying out the first roasting and the second roasting in sequence, the present invention reduces the acid consumption for acid leaching and can be carried out at a relatively low roasting temperature.

[0029] Preferably, the liquid-solid ratio of the water leaching in step (2) is 3:1 - 5:1. For example, it can be 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable. The unit of the liquid-solid ratio is mL / g.

[0030] Preferably, the temperature of the water immersion in step (2) is 25°C - 60°C. For example, it can be 25°C, 30°C, 40°C, 50°C or 60°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0031] Preferably, the time of the water immersion in step (2) is 2h - 4h. For example, it can be 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0032] Preferably, the first pH value in step (3) is 1.2 - 3. For example, it can be 1.2, 1.5, 2, 2.5 or 3, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the first precipitant in step (3) includes oxalic acid and / or sodium hydroxide.

[0034] Preferably, the dosage of the first precipitant in step (3) is 1 times - 1.3 times the theoretical dosage. For example, it can be 1 times, 1.1 times, 1.2 times or 1.3 times, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0035] The theoretical dosage of the first precipitant in the present invention means that the molar ratio of the first precipitant to the total amount of rare earth elements in the water immersion solution is 3:2.

[0036] Preferably, the temperature of the rare earth precipitation treatment in step (3) is 20°C - 60°C. For example, it can be 20°C, 30°C, 40°C, 50°C or 60°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0037] Preferably, the method further includes heat treatment of the rare earth precipitation slag in step (3).

[0038] Preferably, the temperature of the heat treatment is 750°C - 850°C. For example, it can be 750°C, 770°C, 780°C, 800°C, 820°C, 840°C or 850°C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0039] Preferably, the time of the heat treatment is 2h - 4h. For example, it can be 2h, 2.5h, 3h, 3.5h or 4h, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0040] Preferably, the aluminum removing agent in step (4) includes potassium sulfate and / or ammonium sulfate.

[0041] Preferably, the dosage of the aluminum removing agent in step (4) is 1.2 to 1.5 times the theoretical dosage, for example, it can be 1.2 times, 1.3 times, 1.4 times or 1.5 times, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0042] The theoretical dosage of the aluminum removing agent in the present invention means that the molar ratio of the aluminum removing agent to the aluminum element in the rare earth precipitation solution is 0.5:1.

[0043] Preferably, the temperature of the aluminum removing treatment in step (4) is 10°C - 35°C, for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C or 35°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0044] Preferably, the time of the aluminum removing treatment in step (4) is 3h - 6h, for example, it can be 3h, 3.5h, 4h, 4.5h, 5h or 6h, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0045] Preferably, the second pH value in step (5) is 12 - 14, for example, it can be 12, 12.5, 13, 13.5 or 14, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0046] Preferably, the second precipitating agent in step (5) includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide or calcium oxide. Typical but non-limiting combinations include the combination of sodium hydroxide and calcium hydroxide, the combination of calcium hydroxide and calcium oxide, the combination of sodium hydroxide and calcium oxide, or the combination of sodium hydroxide, calcium hydroxide and calcium oxide.

[0047] Preferably, the temperature of the impurity removing treatment in step (5) is 20°C - 85°C, for example, it can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 85°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0048] The calcium removing treatment in the present invention can be a conventional calcium removing treatment method in the art. Exemplarily, sodium carbonate is added according to the calcium content of the impurity removing solution to achieve calcium removing treatment.

[0049] As a preferred technical solution of the method provided by the present invention, the method includes the following steps:

[0050] (1) Acid-leach waste doped lithium-based polishing powder with a D50 particle size not exceeding 74 μm, and perform the first roasting and the second roasting to obtain roasted slag and roasting flue gas;

[0051] The acid leaching is carried out with sulfuric acid having a concentration of 95 wt% or more, and the mass ratio of sulfuric acid to waste lithium-containing polishing powder is 1.6:1 - 2:1;

[0052] The temperature of the first roasting is 200°C - 250°C, and the time is 1 h - 3 h;

[0053] The temperature of the second roasting is 300°C - 400°C, and the time is 1 h - 3 h;

[0054] (2) Leach the roasting slag described in step (1) with water at 25°C - 60°C for 2 h - 4 h to obtain a leaching solution and a leaching residue;

[0055] The liquid-solid ratio of the water leaching is 3:1 - 5:1, and the unit of the liquid-solid ratio is mL / g;

[0056] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution described in step (2) to 1.2 - 3, add a first precipitating agent, and carry out rare earth precipitation treatment at a temperature of 20°C - 60°C to obtain a solution after rare earth precipitation and a rare earth precipitation residue;

[0057] The first precipitating agent includes oxalic acid and / or sodium hydroxide, and the dosage of the first precipitating agent is 1 times - 1.3 times the theoretical dosage;

[0058] The rare earth precipitation residue is heat-treated at a temperature of 750°C - 850°C for 2 h - 4 h to obtain rare earth oxides;

[0059] (4) Mix an aluminum removal agent with the solution after rare earth precipitation described in step (3), and carry out aluminum removal treatment at a temperature of 10°C - 35°C for 3 h - 6 h to obtain alum and a solution after aluminum removal;

[0060] The aluminum removal agent includes potassium sulfate and / or ammonium sulfate;

[0061] The dosage of the aluminum removal agent is 1.2 times - 1.5 times the theoretical dosage;

[0062] (5) Use a second precipitating agent to adjust the pH value of the solution after aluminum removal described in step (4) to 12 - 14, and carry out impurity removal treatment at a temperature of 20°C - 85°C to obtain a solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment, phosphate is added for lithium precipitation treatment to obtain lithium phosphate;

[0063] The second precipitating agent includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, or calcium oxide.

[0064] The numerical ranges described in the present invention not only include the point values exemplified above, but also include any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The method provided by the present invention can not only realize the recovery of rare earths in waste lithium-containing polishing powder, but also obtain high-value-added aluminum-containing products through the method of alum crystallization, ensuring a relatively high recovery rate of lithium; moreover, the process flow of the method provided by the present invention is simple, the recovery cost is low, realizing the high-value-added recycling of waste lithium-containing polishing powder, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a process flow chart of the method provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0068] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0069] In the specific embodiment of the present invention, the waste lithium-containing polishing powder is waste rare earth-doped lithium-based polishing powder, the median particle size D50 of which is 50 μm, and by mass percentage, the main components include La: 16.99%, Ce: 16.98%, Li: 0.54%, Al: 7.6%, Si: 3.40%, F: 2.61%; the above limitations are only for clearly explaining the technical solution of the present invention and are not regarded as further limitations to the present invention.

[0070] Example 1

[0071] This example provides a method for comprehensively recovering valuable components in waste lithium-containing polishing powder as shown in Figure 1 , and the method includes the following steps:

[0072] (1) Acid-leach the waste doped lithium-based polishing powder, perform the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid caustic soda to obtain sodium fluoride;

[0073] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1;

[0074] The temperature of the first roasting is 250 °C and the time is 2 h;

[0075] The temperature of the second roasting is 350 °C and the time is 2 h;

[0076] (2) Leach the roasted slag obtained in step (1) with water at 50 °C for 4 h to obtain a water leaching solution and water leaching residue;

[0077] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0078] (3) Adjust the pH value of the water immersion liquid described in step (2) to 1.5 with sodium hydroxide, add oxalic acid, and carry out rare earth precipitation treatment at a temperature of 60 °C, followed by solid-liquid separation to obtain the liquid after rare earth precipitation and rare earth precipitation residue;

[0079] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0080] Heat-treat the rare earth precipitation residue at a temperature of 800 °C for 2 h to obtain rare earth oxides;

[0081] (4) Mix ammonium sulfate with the liquid after rare earth precipitation described in step (3), heat up to dissolve ammonium sulfate, and then carry out aluminum removal treatment at a temperature of 10 °C for 4 h to obtain alum and the liquid after aluminum removal;

[0082] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0083] (5) Adjust the pH value of the liquid after aluminum removal described in step (4) to 12.5 with calcium hydroxide, and carry out impurity removal treatment at a temperature of 50 °C to obtain the liquid after impurity removal; after the liquid after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0084] Example 2

[0085] This example provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder, and the method includes the following steps:

[0086] (1) Acid-leach waste doped lithium-based polishing powder, carry out the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid alkali to obtain sodium fluoride;

[0087] The acid leaching is carried out with concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.7:1;

[0088] The temperature of the first roasting is 200 °C and the time is 2 h;

[0089] The temperature of the second roasting is 350 °C and the time is 2 h;

[0090] (2) Immerse the roasted slag described in step (1) in water at 40 °C for 4 h to obtain a water immersion liquid and a water immersion residue;

[0091] The liquid-solid ratio of the water immersion is 5:1, and the unit of the liquid-solid ratio is mL / g;

[0092] (3) Adjust the pH value of the water immersion liquid described in step (2) to 1.5 with sodium hydroxide, add oxalic acid, and carry out rare earth precipitation treatment at a temperature of 60 °C, followed by solid-liquid separation to obtain the liquid after rare earth precipitation and rare earth precipitation residue;

[0093] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0094] The rare earth precipitation residue is heat-treated at 800 °C for 2 h to obtain rare earth oxides;

[0095] (4) Mix ammonium sulfate with the liquid after rare earth precipitation in step (3), heat up to dissolve ammonium sulfate, and then perform aluminum removal treatment at 20 °C for 6 h to obtain alum and the liquid after aluminum removal;

[0096] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0097] (5) Use calcium hydroxide to adjust the pH value of the liquid after aluminum removal in step (4) to 13, and perform impurity removal treatment at 40 °C to obtain the liquid after impurity removal; after the liquid after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0098] Example 3

[0099] This example provides a method for comprehensively recovering valuable components in waste lithium-containing polishing powder as Figure 1 shown, and the method includes the following steps:

[0100] (1) Acid-leach waste doped lithium-based polishing powder, perform the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid alkali to obtain sodium fluoride;

[0101] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.4:1;

[0102] The temperature of the first roasting is 250 °C and the time is 2 h;

[0103] The temperature of the second roasting is 350 °C and the time is 2 h;

[0104] (2) Leach the roasted slag in step (1) with water at 50 °C for 4 h to obtain a water leaching solution and a water leaching residue;

[0105] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0106] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution in step (2) to 1.5, add oxalic acid, perform rare earth precipitation treatment at 60 °C, and perform solid-liquid separation to obtain the liquid after rare earth precipitation and the rare earth precipitation residue;

[0107] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0108] The heavy rare earth residue is heat-treated at 800 °C for 2 h to obtain rare earth oxides;

[0109] (4) Ammonium sulfate is mixed with the liquid after rare earth precipitation in step (3), the temperature is raised to dissolve ammonium sulfate, and then aluminum removal treatment is carried out at 30 °C for 6 h to obtain alum and the liquid after aluminum removal;

[0110] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0111] (5) Use calcium hydroxide to adjust the pH value of the liquid after aluminum removal in step (4) to 12.5, and carry out impurity removal treatment at 50 °C to obtain the liquid after impurity removal; after the liquid after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0112] Example 4

[0113] This example provides a method for comprehensively recovering valuable components in waste lithium-containing polishing powder as shown in Figure 1 , and the method includes the following steps:

[0114] (1) Acid-leach the waste doped lithium-based polishing powder, carry out the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid alkali to obtain sodium fluoride;

[0115] The acid leaching is carried out with concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1;

[0116] The temperature of the first roasting is 150 °C and the time is 2 h;

[0117] The temperature of the second roasting is 250 °C and the time is 2 h;

[0118] (2) Leach the roasted slag in step (1) with water at 50 °C for 4 h to obtain a water leaching solution and water leaching residue;

[0119] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0120] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution in step (2) to 1.5, add oxalic acid, carry out rare earth precipitation treatment at 60 °C, and carry out solid-liquid separation to obtain the liquid after rare earth precipitation and heavy rare earth residue;

[0121] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0122] The heavy rare earth residue is heat-treated at 800 °C for 2 h to obtain rare earth oxides;

[0123] (4) Mix ammonium sulfate with the post-rare earth precipitation solution described in step (3), heat up to dissolve ammonium sulfate, and then perform aluminum removal treatment at a temperature of 30°C for 6 hours to obtain alum and the post-aluminum removal solution;

[0124] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0125] (5) Use calcium hydroxide to adjust the pH value of the post-aluminum removal solution described in step (4) to 12.5, and perform impurity removal treatment at a temperature of 50°C to obtain the post-impurity removal solution; after the post-impurity removal solution is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0126] Example 5

[0127] This example provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder, and the method includes the following steps:

[0128] (1) Acid-leach waste doped lithium-based polishing powder, conduct roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid caustic soda to obtain sodium fluoride;

[0129] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1;

[0130] The roasting temperature is 350°C and the time is 2 hours;

[0131] (2) Leach the roasted slag described in step (1) with water at 50°C for 4 hours to obtain a water leaching solution and water leaching residue;

[0132] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0133] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution described in step (2) to 1.5, add oxalic acid, and perform rare earth precipitation treatment at a temperature of 60°C, followed by solid-liquid separation to obtain the post-rare earth precipitation solution and rare earth precipitation residue;

[0134] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0135] The rare earth precipitation residue is heat-treated at a temperature of 800°C for 2 hours to obtain rare earth oxides;

[0136] (4) Mix ammonium sulfate with the post-rare earth precipitation solution described in step (3), heat up to dissolve ammonium sulfate, and then perform aluminum removal treatment at a temperature of 10°C for 4 hours to obtain alum and the post-aluminum removal solution;

[0137] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0138] (5) Adjust the pH value of the solution after aluminum removal in step (4) to 12.5 with calcium hydroxide, and perform impurity removal treatment at a temperature of 50 °C to obtain a solution after impurity removal; after the solution after impurity removal is treated with sodium carbonate to remove calcium, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0139] Example 6

[0140] This example provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder, and the method includes the following steps:

[0141] (1) Acid-leach the waste doped lithium-based polishing powder, perform the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid alkali to obtain sodium fluoride.

[0142] The acid leaching is carried out with concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1.

[0143] The temperature of the first roasting is 250 °C and the time is 2 h.

[0144] The temperature of the second roasting is 350 °C and the time is 2 h.

[0145] (2) Leach the roasted slag in step (1) with water at 50 °C for 4 h to obtain a leaching solution and a leaching residue.

[0146] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g.

[0147] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution in step (2) to 4, add oxalic acid, and perform rare earth precipitation treatment at a temperature of 60 °C, followed by solid-liquid separation to obtain a solution after rare earth precipitation and a rare earth precipitation residue.

[0148] The dosage of oxalic acid is 1.2 times the theoretical dosage.

[0149] The rare earth precipitation residue is heat-treated at a temperature of 800 °C for 2 h to obtain rare earth oxides.

[0150] (4) Mix ammonium sulfate with the solution after rare earth precipitation in step (3), heat up to dissolve ammonium sulfate, and then perform aluminum removal treatment at a temperature of 10 °C for 4 h to obtain alum and a solution after aluminum removal.

[0151] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage.

[0152] (5) Adjust the pH value of the solution after aluminum removal in step (4) to 12.5 with calcium hydroxide, and perform impurity removal treatment at a temperature of 50 °C to obtain a solution after impurity removal; after the solution after impurity removal is treated with sodium carbonate to remove calcium, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0153] Example 7

[0154] This example provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder. The method includes the following steps:

[0155] (1) Acid-leach the waste doped lithium-based polishing powder, perform the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid caustic soda to obtain sodium fluoride;

[0156] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1;

[0157] The temperature of the first roasting is 250°C and the time is 2h;

[0158] The temperature of the second roasting is 350°C and the time is 2h;

[0159] (2) Leach the roasted slag obtained in step (1) with water at 50°C for 4h to obtain a water leaching solution and water leaching residue;

[0160] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0161] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution obtained in step (2) to 1.5, add oxalic acid, and carry out rare earth precipitation treatment at a temperature of 60°C, followed by solid-liquid separation to obtain a solution after rare earth precipitation and rare earth precipitation residue;

[0162] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0163] The rare earth precipitation residue is heat-treated at a temperature of 800°C for 2h to obtain rare earth oxides;

[0164] (4) Mix ammonium sulfate with the solution after rare earth precipitation obtained in step (3), heat up to dissolve ammonium sulfate, and then carry out aluminum removal treatment at a temperature of 50°C for 8h to obtain alum and a solution after aluminum removal;

[0165] The dosage of the aluminum removal agent is 1.0 times the theoretical dosage;

[0166] (5) Use calcium hydroxide to adjust the pH value of the solution after aluminum removal obtained in step (4) to 13, carry out impurity removal treatment at a temperature of 50°C to obtain a solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0167] Example 8

[0168] This example provides a method for comprehensively recovering valuable components from waste lithium-containing polishing powder. The method includes the following steps:

[0169] (1) Acid-leach the waste doped lithium-based polishing powder, conduct the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid caustic soda to obtain sodium fluoride;

[0170] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.8:1;

[0171] The temperature of the first roasting is 250 °C and the time is 2 h;

[0172] The temperature of the second roasting is 350 °C and the time is 2 h;

[0173] (2) Leach the roasted slag obtained in step (1) with water at 50 °C for 4 h to obtain a water leaching solution and water leaching residue;

[0174] The liquid-solid ratio of the water leaching is 4:1, and the unit of the liquid-solid ratio is mL / g;

[0175] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution obtained in step (2) to 1.5, add oxalic acid, and carry out rare earth precipitation treatment at a temperature of 60 °C, followed by solid-liquid separation to obtain the solution after rare earth precipitation and rare earth precipitation residue;

[0176] The dosage of oxalic acid is 1.2 times the theoretical dosage;

[0177] The rare earth precipitation residue is heat-treated at a temperature of 800 °C for 2 h to obtain rare earth oxides;

[0178] (4) Mix ammonium sulfate with the solution after rare earth precipitation obtained in step (3), heat up to dissolve ammonium sulfate, and then carry out aluminum removal treatment at a temperature of 10 °C for 4 h to obtain alum and the solution after aluminum removal;

[0179] The dosage of the aluminum removal agent is 1.3 times the theoretical dosage;

[0180] (5) Use calcium hydroxide to adjust the pH value of the solution after aluminum removal obtained in step (4) to 9, and carry out impurity removal treatment at a temperature of 50 °C to obtain the solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0181] Example 9

[0182] This example provides a method for comprehensively recovering valuable components in waste lithium-containing polishing powder. The method includes the following steps:

[0183] (1) Acid-leach the waste doped lithium-based polishing powder, conduct the first roasting and the second roasting to obtain roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid caustic soda to obtain sodium fluoride;

[0184] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 1.6:1;

[0185] The temperature of the first roasting is 200 °C and the time is 3 h;

[0186] The temperature of the second roasting is 300 °C and the time is 3 h;

[0187] (2) Leach the roasted slag obtained in step (1) with water at 60 °C for 2 h to obtain a water leaching solution and a water leaching residue;

[0188] The liquid-solid ratio of the water leaching is 5:1, and the unit of the liquid-solid ratio is mL / g;

[0189] (3) Use sodium hydroxide to adjust the pH value of the water leaching solution obtained in step (2) to 1.2, add oxalic acid, and carry out rare earth precipitation treatment at a temperature of 20 °C, followed by solid-liquid separation to obtain a solution after rare earth precipitation and a rare earth precipitation residue;

[0190] The dosage of oxalic acid is 1.3 times the theoretical dosage;

[0191] The rare earth precipitation residue is heat-treated at a temperature of 750 °C for 4 h to obtain rare earth oxides;

[0192] (4) Mix ammonium sulfate with the solution after rare earth precipitation obtained in step (3), heat up to dissolve ammonium sulfate, and then carry out aluminum removal treatment at a temperature of 10 °C for 6 h to obtain alum and a solution after aluminum removal;

[0193] The dosage of the aluminum removal agent is 1.2 times the theoretical dosage;

[0194] (5) Use calcium hydroxide to adjust the pH value of the solution after aluminum removal obtained in step (4) to 12, and carry out impurity removal treatment at a temperature of 20 °C to obtain a solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0195] Example 10

[0196] This example provides a method for comprehensively recovering valuable components in waste lithium-containing polishing powder. The method includes the following steps:

[0197] (1) Acid leach waste doped lithium-based polishing powder, carry out the first roasting and the second roasting to obtain a roasted slag and roasting flue gas; the roasting flue gas is absorbed by liquid alkali to obtain sodium fluoride;

[0198] The acid leaching is carried out using concentrated sulfuric acid with a concentration of 98 wt%, and the mass ratio of concentrated sulfuric acid to waste lithium-containing polishing powder is 2:1;

[0199] The temperature of the first roasting is 250 °C and the time is 1 h;

[0200] The temperature of the second calcination is 400 °C and the time is 1 h;

[0201] (2) Immerse the calcined slag described in step (1) in water at 25 °C for 4 h to obtain a water immersion solution and water immersion slag;

[0202] The liquid-solid ratio of the water immersion is 3:1, and the unit of the liquid-solid ratio is mL / g;

[0203] (3) Use sodium hydroxide to adjust the pH value of the water immersion solution described in step (2) to 3, add oxalic acid, and perform rare earth precipitation treatment at a temperature of 60 °C, followed by solid-liquid separation to obtain a solution after rare earth precipitation and rare earth precipitation slag;

[0204] The dosage of oxalic acid is 1 times the theoretical dosage;

[0205] The rare earth precipitation slag is heat-treated at a temperature of 850 °C for 2 h to obtain rare earth oxides;

[0206] (4) Mix ammonium sulfate with the solution after rare earth precipitation described in step (3), heat up to dissolve ammonium sulfate, and then perform aluminum removal treatment at a temperature of 35 °C for 3 h to obtain alum and a solution after aluminum removal;

[0207] The dosage of the aluminum removal agent is 1.5 times the theoretical dosage;

[0208] (5) Use calcium hydroxide to adjust the pH value of the solution after aluminum removal described in step (4) to 14, and perform impurity removal treatment at a temperature of 85 °C to obtain a solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment with sodium carbonate, sodium phosphate is added for lithium precipitation treatment to obtain lithium phosphate.

[0209] Comparative example

[0210] The difference between this example and Example 1 is that in this example, in step (4), liquid alkali is directly added to adjust the pH to 4 for aluminum removal to obtain aluminum removal slag and a solution after aluminum removal.

[0211] Performance characterization

[0212] The lithium leaching rate, rare earth precipitation rate, La2O3 content and CeO2 content in rare earth oxides, alum yield, main alum content, overall process lithium recovery rate, and main lithium phosphate content in the method provided in the above examples were measured, and the results are shown in Table 1.

[0213] Table 1

[0214]

[0215]

[0216] In summary, the method provided by the present invention can not only realize the recovery of rare earths in waste lithium-containing polishing powder, but also obtain high-value-added aluminum-containing products through the method of forming alum crystals, ensuring a relatively high recovery rate of lithium. Moreover, the process flow of the method provided by the present invention is simple, the recovery cost is low, realizing the high-value-added recycling of waste lithium-containing polishing powder, and is suitable for large-scale industrial production.

[0217] The applicant declares that the above is only the specific implementation manner 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 any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for comprehensively recovering valuable components in waste lithium-containing polishing powder, characterized in that, The method includes the following steps: (1) Acid-leach the waste lithium-containing polishing powder, and perform roasting to obtain roasted slag and roasting flue gas; (2) Water-leach the roasted slag obtained in step (1) to obtain a water-leachate and water-leached slag; (3) Adjust the pH value of the water-leachate obtained in step (2) to a first pH value, add a first precipitant for rare earth precipitation treatment to obtain a post-rare earth precipitation solution and rare earth precipitation slag; (4) Mix an aluminum-removing agent with the post-rare earth precipitation solution obtained in step (3), and perform aluminum-removing treatment to obtain alum and post-aluminum-removing solution; (5) Use a second precipitant to adjust the pH value of the post-aluminum-removing solution obtained in step (4) to a second pH value, perform impurity removal treatment to obtain a post-impurity removal solution; after performing calcium removal treatment on the post-impurity removal solution, add phosphate for lithium precipitation treatment to obtain lithium phosphate.

2. The method according to claim 1, characterized in that, The acid leaching in step (1) is carried out using sulfuric acid with a concentration of more than 95 wt%; Preferably, the mass ratio of the sulfuric acid to the waste lithium-containing polishing powder is 1.6:1 - 2:

1.

3. The method according to claim 1 or 2, characterized in that, The roasting in step (1) includes a first roasting and a second roasting carried out in sequence; Preferably, the temperature of the first roasting is 200°C - 250°C, and the time is 1 h - 3 h; Preferably, the temperature of the second roasting is 300°C - 400°C, and the time is 1 h - 3 h.

4. The method according to any one of claims 1 to 3, characterized in that, The liquid-solid ratio of the water leaching in step (2) is 3:1 - 5:1, and the unit of the liquid-solid ratio is mL / g; Preferably, the temperature of the water leaching in step (2) is 25°C - 60°C; Preferably, the time of the water leaching in step (2) is 2 h - 4 h.

5. The method according to any one of claims 1-4, characterized in that, The first pH value in step (3) is 1.2 - 3; Preferably, the first precipitant in step (3) includes oxalic acid and / or sodium hydroxide; Preferably, the dosage of the first precipitant in step (3) is 1 times - 1.3 times the theoretical dosage; Preferably, the temperature of the rare earth precipitation treatment in step (3) is 20°C - 60°C.

6. The method according to claim 5, characterized in that, The method further includes performing heat treatment on the rare earth precipitation slag obtained in step (3); Preferably, the temperature of the heat treatment is 750°C - 850°C; Preferably, the time of the heat treatment is 2 h - 4 h.

7. The method according to any one of claims 1-6, characterized in that, The aluminum-removing agent in step (4) includes potassium sulfate and / or ammonium sulfate; Preferably, the dosage of the aluminum-removing agent in step (4) is 1.2 times - 1.5 times the theoretical dosage; Preferably, the temperature of the aluminum-removing treatment in step (4) is 10°C - 35°C; Preferably, the time of the aluminum-removing treatment in step (4) is 3 h - 6 h.

8. The method according to any one of claims 1-7, characterized in that The second pH value in step (5) is 12 - 14; Preferably, the second precipitant in step (5) includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide, or calcium oxide; Preferably, the temperature of the impurity removal treatment in step (5) is 20°C - 85°C.

9. The method according to any one of claims 1 - 8, characterized in that, The waste lithium-containing polishing powder is waste rare earth-doped lithium-based polishing powder, and its specific components and mass contents include: La: 16.99%, Ce: 16.98%, Li: 0.54%, Al: 7.6%, Si: 3.40%, F: 2.61%.

10. The method according to claim 1, wherein The method includes the following steps: (1) Acid-leach the waste doped lithium-based polishing powder with a particle size D50 not exceeding 74 μm, and perform a first roasting and a second roasting to obtain roasted slag and roasting flue gas; The acid leaching is carried out using sulfuric acid with a concentration of more than 95 wt%, and the mass ratio of sulfuric acid to waste lithium-containing polishing powder is 1.6:1 - 2:1; The temperature of the first roasting is 200°C - 250°C, and the time is 1 h - 3 h; The temperature of the second roasting is 300°C - 400°C, and the time is 1 h - 3 h; (2) Leach the roasting slag described in step (1) with water at 25°C - 60°C for 2 h - 4 h to obtain a water leaching solution and water leaching residue; The liquid-solid ratio of the water leaching is 3:1 - 5:1, and the unit of the liquid-solid ratio is mL / g; (3) Use sodium hydroxide to adjust the pH value of the water leaching solution described in step (2) to 1.2 - 3, add a first precipitating agent, and carry out rare earth precipitation treatment at a temperature of 20°C - 60°C to obtain a solution after rare earth precipitation and rare earth precipitation residue; The first precipitating agent includes oxalic acid and / or sodium hydroxide, and the dosage of the first precipitating agent is 1 times - 1.3 times the theoretical dosage; The rare earth precipitation residue is heat-treated at a temperature of 750°C - 850°C for 2 h - 4 h to obtain rare earth oxides; (4) Mix an aluminum-removing agent with the solution after rare earth precipitation described in step (3), and carry out aluminum-removing treatment at a temperature of 10°C - 35°C for 3 h - 6 h to obtain alum and a solution after aluminum removal; The aluminum-removing agent includes potassium sulfate and / or ammonium sulfate; The dosage of the aluminum-removing agent is 1.2 times - 1.5 times the theoretical dosage; (5) Use a second precipitating agent to adjust the pH value of the solution after aluminum removal described in step (4) to 12 - 14, and carry out impurity removal treatment at a temperature of 20°C - 85°C to obtain a solution after impurity removal; after the solution after impurity removal is subjected to calcium removal treatment, phosphate is added for lithium precipitation treatment to obtain lithium phosphate; The second precipitating agent includes any one or a combination of at least two of sodium hydroxide, calcium hydroxide or calcium oxide.

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