Methods for the comprehensive recovery of tantalum, niobium and tin from lithium slag

Abstract

This invention relates to a comprehensive recovery method for lithium slag, specifically a method for recovering rare metal elements such as tantalum, niobium, and tin from lithium slag, belonging to the field of lithium slag recovery technology. The technical problem solved by this invention is to provide a method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag with a high recovery rate. This method first involves pulping, classifying, and discarding the lithium slag tailings, followed by gravity separation, grinding, and magnetic separation steps for different particle sizes to obtain tantalum, niobium, and tin concentrate. This not only significantly reduces beneficiation costs and improves separation efficiency but also reduces the loss of fine-grained tantalum, niobium, and tin minerals in the tailings, thereby increasing the recovery rate of tantalum, niobium, and tin. Differentiated shaking table gravity separation with different bed surfaces is used on the concentrate after classification and tailings discarding according to different particle sizes, which can significantly improve the grade and recovery rate of tantalum, niobium, and tin concentrate and reduce the loss rate of fine-grained tantalum, niobium, and tin minerals in the shaking table gravity separation tailings. This invention's method can effectively separate tantalum, niobium, and tin, obtaining high-quality tantalum, niobium, and tin concentrates with a high recovery rate.

Description

Technical Field

[0001] This invention relates to a comprehensive method for the recovery of lithium slag, specifically a method for recovering rare metal elements such as tantalum, niobium, and tin from lithium slag, and belongs to the field of lithium slag recovery technology. Background Technology

[0002] Spodumene is an important lithium mineral, mainly composed of lithium aluminum silicate, and usually associated with valuable metals such as tantalum, niobium, and tin. With the widespread application of lithium-ion batteries, the demand for lithium has increased significantly, and lithium extraction technology from spodumene has also developed rapidly. Lithium extraction from spodumene produces 8-10 tons of lithium slag for every ton of lithium carbonate produced. Based on current lithium salt production capacity, China generates over 5 million tons of spodumene smelting slag annually. The (Ta+Nb)₂O₅ content in this slag is 100-180 ppm, and the Sn content is 100-200 ppm. Although the tantalum, niobium, and tin content in the slag is relatively low, if the rare metals tantalum, niobium, and tin can be economically and efficiently recovered, it still has high economic value.

[0003] The main chemical composition analysis data of a certain lithium slag are shown in Table 1.

[0004] Table 1. Analysis data of major chemical components in lithium slag

[0005] content(%) 6.82 0.90 20.22 52.08 0.32 0.50 0.28 5.25 Components MgO <![CDATA[Ta2O5]]> <![CDATA[Nb2O5]]> Sn <![CDATA[B2O3]]> <![CDATA[P2O5]]> <![CDATA[TiO2]]> Loss on ignition content(%) 0.22 0.008 0.006 0.02 0.24 0.23 0.09 9.69

[0006] Mineralogical studies of lithium slag processes show that lithium slag contains low levels of tantalum, niobium, and tin, which are dispersed across different particle sizes. Approximately 30% of the tantalum, niobium, and tin minerals are distributed in particles smaller than 20 μm. Furthermore, most of the tantalum, niobium, and tin minerals in lithium slag are encapsulated in or associated with glass phases. This is one of the main differences between lithium slag and primary tantalum, niobium, and tin ores. The complex intercalation characteristics of tantalum, niobium, and tin minerals in lithium slag are the main reason for the difficulty in recovering tantalum, niobium, and tin metals from lithium slag.

[0007] For the recovery of valuable metals from lithium slag, existing technologies mainly employ methods such as wet leaching and pyrometallurgical smelting. Wet leaching involves contacting lithium slag with leaching agents such as acids or alkalis, dissolving the valuable metals in the solution, and then recovering them through extraction and precipitation. Pyrometallurgical smelting involves melting lithium slag at high temperatures and then recovering the valuable metals through electrolysis or other methods. Current technological challenges: Existing technologies for recovering valuable metals from lithium slag still have several problems. First, existing methods such as wet leaching and pyrometallurgical smelting typically require large amounts of chemical reagents and energy, resulting in high costs and hindering large-scale industrial application. Second, these methods may generate large amounts of wastewater and waste gas during the recovery process, causing environmental pollution. Finally, due to the low content of valuable metals in lithium slag, conventional beneficiation methods are also difficult to achieve efficient recovery, often leading to low recovery rates and significant resource waste. Therefore, how to recover low-content valuable metals from lithium slag in a low-cost and environmentally friendly manner is a pressing issue that needs to be addressed in this field.

[0008] Patents CN113976309A, CN117065916A, CN117165787A, and CN116532235A all relate to the recovery and utilization of rare metals tantalum and niobium from lithium slag, primarily employing magnetic separation + gravity separation processes. Patent CN114226413A discloses a method for recovering tantalum and niobium from lithium slag using flotation + gravity separation. However, the processes described in these patents result in low tantalum and niobium recovery rates, difficulty in recovering fine-grained tantalum and niobium, and a lack of tin separation and recovery, leading to a waste of tin resources and difficulty in obtaining high-quality tantalum and niobium concentrates. Furthermore, due to the extremely low content of rare metals tantalum, niobium, and tin in the raw materials, directly using magnetic separation or flotation to pre-enrich tantalum and niobium results in large processing volumes, high separation costs, and poor economic efficiency. Summary of the Invention

[0009] To address the above deficiencies, the technical problem solved by this invention is to provide a method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag with a high recovery rate.

[0010] The present invention discloses a method for the comprehensive recovery of tantalum, niobium and tin from lithium slag. First, the lithium slag is slurried and then classified to obtain coarse-grained slurry and fine-grained slurry. Then, the coarse-grained slurry and the fine-grained slurry are respectively subjected to tailings removal and gravity separation to obtain a mixed tantalum, niobium and tin concentrate.

[0011] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag specifically includes the following steps:

[0012] S1. Pulping: Mix water and lithium slag to obtain slurry;

[0013] S2, Classification: The slurry from step S1 is classified to obtain coarse-grained and fine-grained slurries respectively.

[0014] S3. Coarse-grained slurry tailings: The coarse-grained slurry described in step S2 is subjected to tailings to obtain coarse-grained tailings concentrate and coarse-grained tailings ore.

[0015] S4. Fine-grained slurry tailings: The fine-grained slurry described in step S2 is subjected to tailings to obtain fine-grained tailings concentrate and fine-grained tailings.

[0016] S5. Gravity separation of coarse-grained tailings concentrate: The coarse-grained tailings concentrate described in step S3 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate A, gravity concentrate A and gravity tailings A.

[0017] S6. Gravity separation of fine-grained tailings concentrate: The fine-grained tailings concentrate described in step S4 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate B, gravity concentrate B and gravity tailings B.

[0018] S7. Concentrate merging: Merge gravity concentrate A from step S5 and gravity concentrate B from step S6 to obtain a tantalum-niobium-tin mixed concentrate.

[0019] In one embodiment of the present invention, in step S1, the mass concentration of the slurry is 10% to 60%. In some specific embodiments, in step S1, the mass concentration of the slurry is 20% to 40%.

[0020] In some embodiments of the present invention, in step S2, the equipment used for grading includes one or a combination of hydrocyclones, high-frequency vibrating fine screens, and spiral classifiers; the particle size of the grading is 74μm to 150μm.

[0021] In some embodiments of the present invention, the equipment used for tailings removal in step S3 includes one or a combination of a spiral chute, a blanket mill, a fabric-laying chute, and a jig. In some embodiments of the present invention, the tailings removal rate in step S3 is 20% to 98%. In some specific embodiments, the tailings removal rate in step S3 is 50% to 90%.

[0022] In some embodiments of the present invention, the equipment used for tailings removal in step S4 includes one or more combinations of spiral sluices, blanket mills, cloth-laying sluices, and jigs. In some embodiments of the present invention, the tailings removal rate in step S4 is 20% to 98%. In some specific embodiments, the tailings removal rate in step S4 is 50% to 90%. In steps S5 and S6, the equipment used for gravity separation includes one or more combinations of composite bed shaking tables, fine sand shaking tables, slime shaking tables, suspended cone concentrators, and centrifuges.

[0023] In some embodiments of the present invention, the equipment used for gravity separation in steps S5 and S6 includes one or more combinations of composite bed shaking table, fine sand shaking table, slime shaking table, suspended cone concentrator, and centrifuge.

[0024] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium and tin from lithium slag further includes at least one of the following steps:

[0025] S8. Processing of re-selected ore A: Concentrate and grind the re-selected ore A described in step S5, and then return it to step S4 for tailings disposal.

[0026] S9. Re-selecting Ore B: Return the re-selected ore B described in step S6 to step S4 for tailings disposal.

[0027] In one embodiment of the present invention, in step S8, the equipment used for concentration includes one or more combinations of hydrocyclones, thickeners, and slurries; the grinding includes one or more combinations of ball mills, vertical mills, and tower mills; and the content of grinding fineness below 74 μm is 50% to 100%. In a preferred embodiment, the content of grinding fineness below 74 μm is 80% to 95%.

[0028] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium and tin from lithium slag further includes grinding and magnetic separation of the obtained tantalum, niobium and tin mixed concentrate to obtain tantalum, niobium concentrate and tin concentrate.

[0029] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag specifically includes the following steps:

[0030] S10. Grinding: Grind the tantalum-niobium-tin mixed concentrate described in step S7 to obtain fine-grained tantalum-niobium-tin mixed concentrate;

[0031] S11. Magnetic separation: The fine-grained tantalum-niobium-tin mixed concentrate described in step S10 is subjected to strong magnetic separation to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained respectively. The filtrate enters the water recycling tank for recycling.

[0032] S12. Tailings treatment: The coarse-grained tailings, fine-grained tailings, gravity separation tailings A and gravity separation tailings B are combined and filtered. The filter residue is used as the total tailings, and the filtrate is recycled into the water return pool.

[0033] In one specific embodiment, step S10 involves grinding, which includes one or a combination of ball milling, vertical milling, and tower milling. In one embodiment of the invention, the grinding fineness is 30% to 95% of the material having a content of 38 μm or less. In a preferred embodiment, the grinding fineness is 70% to 90% of the material having a content of 38 μm or less.

[0034] In one specific embodiment, in step S11, the equipment used for strong magnetic separation includes one or a combination of high-gradient magnetic separators, drum magnetic separators, and belt magnetic separators. In one embodiment of the invention, the magnetic field strength of the strong magnetic separation is 0.3T to 1.5T. In a preferred embodiment, the magnetic field strength of the strong magnetic separation is 0.8T to 1.2T.

[0035] In one specific embodiment, in steps S11 and S12, the equipment used for filtration includes one or a combination of ceramic filters, disc filters, and plate and frame filter presses.

[0036] In one embodiment of the present invention, the recycling rate of the reclaimed water in both steps S11 and S12 is 100%.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The method of this invention first involves pulping, classifying, and discarding lithium slag. Then, through gravity separation, grinding, and magnetic separation, tantalum-niobium-tin concentrate is obtained. The lithium slag is pre-classified before being discarded as tailings. Different tailings discarding equipment is selected for different particle sizes, which not only significantly reduces the feed rate for deep enrichment of tantalum-niobium-tin, thereby reducing beneficiation costs and improving separation efficiency, but also reduces the loss of fine-grained tantalum-niobium-tin minerals in the tailings, increasing the recovery rate of tantalum-niobium-tin. Differentiated shaking table gravity separation with different bed surfaces is used on the concentrate after classification and tailings discarding according to different particle sizes, which can significantly improve the grade and recovery rate of tantalum-niobium-tin concentrate and reduce the loss rate of fine-grained tantalum-niobium-tin minerals in the shaking table gravity separation tailings.

[0039] The method of this invention can effectively separate tantalum, niobium, and tin, resulting in a Sn content of <5% in tantalum-niobium concentrate, a Ta₂O₅ content of <3% in tin concentrate, and a tantalum-niobium content (based on oxides) of <5%. This method yields high-quality tantalum-niobium and tin concentrates with high recovery rates: tantalum-niobium concentrate with Ta₂O₅ grade ≥20% and tantalum recovery ≥60%; Nb₂O₅ grade ≥14% and niobium recovery ≥55%; and tin concentrate with Sn grade ≥55% and tin recovery ≥60%. Attached Figure Description

[0040] Figure 1 This is a process flow diagram of the method for comprehensive recovery of tantalum, niobium and tin from lithium slag in an embodiment of the present invention. Detailed Implementation

[0041] The present invention discloses a method for the comprehensive recovery of tantalum, niobium and tin from lithium slag. First, the lithium slag is slurried and then classified to obtain coarse-grained slurry and fine-grained slurry. Then, the coarse-grained slurry and the fine-grained slurry are respectively subjected to tailings removal and gravity separation to obtain a mixed tantalum, niobium and tin concentrate.

[0042] The method of this invention employs pre-classification followed by tailings removal. Different tailings removal equipment can be used for materials of different particle sizes to achieve efficient tailings removal. Firstly, it can significantly reduce the processing volume of subsequent gravity separation processes and improve the separation efficiency of tantalum, niobium, and tin. Secondly, by using tailings removal equipment appropriate to the different mineral particle sizes, the loss rate of tantalum, niobium, and tin metals in the tailings can be significantly reduced. The loss rate of tantalum, niobium, and tin metals in the tailings is less than 15%. If the lithium slag is not pre-classified and treated for tailings removal, the loss rate of fine-grained tantalum, niobium, and tin minerals will be high during the tailings removal stage, and the overall recovery rate of tantalum, niobium, and tin will be 5-10% lower. The main reason is that the content of tantalum, niobium, and tin minerals is low, and they are dispersed in different particle sizes of lithium slag. During the tailings removal process, fine-grained tantalum, niobium, and tin minerals are easily removed together with coarse-grained gangue minerals.

[0043] Furthermore, differentiated shaking table gravity separation can be used on concentrates after graded tailings disposal, depending on the particle size. This can significantly improve the grade and recovery rate of tantalum-niobium-tin concentrates and reduce the loss rate of fine-grained tantalum-niobium-tin minerals in the shaking table gravity separation tailings. Without differentiated shaking table gravity separation for coarse and fine particles, fine-grained tantalum-niobium-tin minerals and coarse-grained gangue minerals cannot form separate zones and will be lost in the shaking table tailings.

[0044] In some embodiments of the present invention, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag specifically includes the following steps:

[0045] S1. Pulping: Mix water and lithium slag to obtain slurry;

[0046] S2, Classification: The slurry from step S1 is classified to obtain coarse-grained and fine-grained slurries respectively.

[0047] S3. Coarse-grained slurry tailings: The coarse-grained slurry described in step S2 is subjected to tailings to obtain coarse-grained tailings concentrate and coarse-grained tailings ore.

[0048] S4. Fine-grained slurry tailings: The fine-grained slurry described in step S2 is subjected to tailings to obtain fine-grained tailings concentrate and fine-grained tailings.

[0049] S5. Gravity separation of coarse-grained tailings concentrate: The coarse-grained tailings concentrate described in step S3 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate A, gravity concentrate A and gravity tailings A.

[0050] S6. Gravity separation of fine-grained tailings concentrate: The fine-grained tailings concentrate described in step S4 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate B, gravity concentrate B and gravity tailings B.

[0051] S7. Concentrate merging: Merge gravity concentrate A from step S5 and gravity concentrate B from step S6 to obtain a tantalum-niobium-tin mixed concentrate.

[0052] Step S1 involves pulping, where water and lithium slag are mixed to obtain a slurry. Clean water or recycled water can be used to mix the lithium slag and stir to form the slurry. In one embodiment of the invention, the mass concentration of the slurry is 10%–60%. In some specific embodiments, the mass concentration of the slurry is 20%–40%.

[0053] Step S2 is classification: the slurry from step S1 is classified to obtain coarse and fine slurries. In this step, classification can be performed using one or a combination of hydrocyclones, high-frequency vibrating screens, and spiral classifiers.

[0054] In some embodiments of the present invention, the particle size for grading is 74 μm to 150 μm. That is, grading can use any value from 74 μm to 150 μm as the grading standard. For example, if the particle size is 74 μm, particles with a size greater than or equal to 74 μm are considered coarse-grained, and particles smaller than 74 μm are considered fine-grained; or if the particle size is 150 μm, particles with a size greater than or equal to 150 μm are considered coarse-grained, and particles smaller than 150 μm are considered fine-grained; or if the particle size is 100 μm... μm, meaning particles with a size greater than or equal to 100 μm are coarse particles, particles smaller than 100 μm are fine particles, and so on. The particle sizes for classification can be 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, etc.

[0055] Step S3 involves tailings disposal of the coarse-grained slurry, which is performed on the coarse-grained slurry described in step S2 to obtain coarse-grained tailings concentrate and coarse-grained tailings ore.

[0056] In some embodiments of the present invention, the equipment used for tailings removal in step S3 includes one or a combination of spiral sluices, blanket machines, fabric-laying sluices, and jigs. In some embodiments of the present invention, the tailings removal rate in step S3 is 20% to 98%. In some specific embodiments, the tailings removal rate in step S3 is 50% to 90%.

[0057] Step S4 involves tailings removal from the fine-grained slurry, which is then processed to remove tailings, yielding fine-grained tailings concentrate and fine-grained tailings ore.

[0058] The tailings removal process in step S4 can use the same equipment and have a different tailings removal rate than step S3. In some embodiments of the invention, the equipment used in step S4 includes one or a combination of spiral sluices, blanket mills, fabric sluices, and jigs. In some embodiments of the invention, the tailings removal rate in step S4 is 20%–98%. In some specific embodiments, the tailings removal rate in step S4 is 50%–90%.

[0059] Step S5 involves gravity separation of the coarse-grained tailings concentrate obtained in step S3. This process involves tantalum-niobium-tin gravity separation to obtain gravity concentrate A, gravity ore A, and gravity tailings A. In some embodiments of this invention, the equipment used in step S5 includes one or more combinations of a composite bed shaking table, a fine sand shaking table, a slime shaking table, a suspended cone concentrator, and a centrifuge.

[0060] Step S6 involves gravity separation of the fine-grained tailings concentrate. The fine-grained tailings concentrate from step S4 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate B, gravity ore B, and gravity tailings B. In some embodiments of the present invention, the equipment used in step S6 for gravity separation includes one or a combination of several of the following: a composite bed shaking table, a fine sand shaking table, a slime shaking table, a suspended cone concentrator, and a centrifuge.

[0061] Step S7 is to combine the concentrates, combining the gravity concentrate A from step S5 and the gravity concentrate B from step S6 to obtain a tantalum-niobium-tin mixed concentrate.

[0062] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium and tin from lithium slag further includes at least one of the following steps:

[0063] S8. Processing of re-selected ore A: Concentrate and grind the re-selected ore A described in step S5, and then return it to step S4 for tailings disposal.

[0064] S9. Re-selecting Ore B: Return the re-selected ore B described in step S6 to step S4 for tailings disposal.

[0065] Processing ore A or ore B by gravity separation can recover some resources. Step S8 involves processing ore A, and step S9 involves processing ore B. In one embodiment of the invention, in step S8, the equipment used for concentration includes one or more combinations of hydrocyclones, thickeners, and slurries; the grinding includes one or more combinations of ball mills, vertical mills, and tower mills; the content of minerals with a grinding fineness of 74 μm or less is 50%–100%, and in a preferred embodiment, the content of minerals with a grinding fineness of 74 μm or less is 80%–95%.

[0066] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium and tin from lithium slag further includes grinding and magnetic separation of the obtained tantalum, niobium and tin mixed concentrate to obtain tantalum, niobium concentrate and tin concentrate.

[0067] In one embodiment of the present invention, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag specifically includes the following steps:

[0068] S10. Grinding: Grind the tantalum-niobium-tin mixed concentrate described in step S7 to obtain fine-grained tantalum-niobium-tin mixed concentrate;

[0069] S11. Magnetic separation: The fine-grained tantalum-niobium-tin mixed concentrate described in step S10 is subjected to strong magnetic separation to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained respectively. The filtrate enters the water recycling tank for recycling.

[0070] S12. Tailings treatment: The coarse-grained tailings, fine-grained tailings, gravity separation tailings A and gravity separation tailings B are combined and filtered. The filter residue is used as the total tailings, and the filtrate is recycled into the water return pool.

[0071] Through steps S10-S12, tantalum-niobium concentrate and tin concentrate can be recovered separately from a mixed tantalum-niobium-tin concentrate. Because lithium slag differs significantly from primary ore, most of the tantalum-niobium-tin minerals in the slag are encapsulated or intergrowthed by glassy phase materials. Direct magnetic separation results in high tantalum-niobium-tin content in the concentrate. Since tin in the tantalum-niobium concentrate and tantalum-niobium in the tin concentrate often cannot be valued separately, leading to resource loss, this invention proposes a fine grinding-strong magnetic separation process that can effectively separate tantalum-niobium-tin to obtain higher quality tantalum-niobium concentrate and tin concentrate. The Sn content in the tantalum-niobium concentrate is <5%, and the Ta2O5 content in the tin concentrate is <3%.

[0072] Step S10 involves grinding the tantalum-niobium-tin mixed concentrate obtained in step S7 to obtain a fine-grained tantalum-niobium-tin mixed concentrate. Grinding techniques commonly used in the art are applicable to this invention. In one specific embodiment, the grinding includes one or a combination of ball milling, vertical milling, and tower milling. In one embodiment of this invention, the grinding fineness is 30% to 95% for particles smaller than 38 μm. In a preferred embodiment, the grinding fineness is 70% to 90% for particles smaller than 38 μm.

[0073] Step S11 is magnetic separation, in which the fine-grained tantalum-niobium-tin mixed concentrate described in step S10 is subjected to strong magnetic separation to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained respectively, and the filtrate enters the recycling pool for reuse.

[0074] In one embodiment of the present invention, the equipment used for strong magnetic separation includes one or a combination of high gradient magnetic separator, drum magnetic separator, and belt magnetic separator.

[0075] In one embodiment of the present invention, the magnetic field strength of the strong magnetic separator is 0.3T to 1.5T. In a preferred embodiment, the magnetic field strength of the strong magnetic separator is 0.8T to 1.2T.

[0076] The filtration in step S11 can also be performed using conventional filtration methods in the art. In some specific embodiments, the equipment used for filtration includes one or a combination of ceramic filters, disc filters, and plate and frame filter presses.

[0077] Step S12 involves tailings treatment, where coarse-grained tailings, fine-grained tailings, gravity separation tailings A, and gravity separation tailings B are combined and filtered. The filter residue is treated as total tailings, and the filtrate is recycled into a return water tank. This filtration step can be the same as or different from step S11. In some specific embodiments, the filtration equipment includes one or a combination of ceramic filters, disc filters, and plate and frame filter presses.

[0078] In one embodiment of the present invention, the recycling rate of the reclaimed water in both steps S11 and S12 is 100%.

[0079] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the described embodiments. The lithium slag used in the examples is shown in Table 1.

[0080] Example 1

[0081] like Figure 1 As shown, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0082] (1) Add lithium slag to clean water and stir to make slurry with a mass concentration of 20%. Then, enter the hydrocyclone for pre-classification to obtain coarse slurry and fine slurry with a classification particle size of 74μm.

[0083] (2) The coarse-grained slurry was disposed of by a cloth-laying chute to obtain coarse-grained tailings concentrate and coarse-grained tailings. The tailings removal rate was 80%.

[0084] (3) The fine-grained slurry is subjected to tailings removal operation using a blanket mill to obtain fine-grained tailings concentrate and fine-grained tailings. The tailings removal rate is 80%.

[0085] (4) The coarse-grained tailings concentrate is subjected to ore sand shaking table gravity separation to obtain coarse-grained tantalum-niobium-tin mixed concentrate, shaking table coarse-grained middlings and shaking table coarse-grained tailings. The shaking table coarse-grained middlings is ground by ball mill to a content of 80% below 74μm, and then returned to the blanket machine for tailings disposal.

[0086] (5) Fine-grained tailings concentrate is subjected to ore slime type shaking table gravity separation to obtain fine-grained tantalum-niobium-tin mixed concentrate, fine-grained middlings and fine-grained tailings; fine-grained middlings are returned to the blanket machine tailings disposal operation.

[0087] (6) Combine coarse-grained tantalum-niobium-tin mixed concentrate and fine-grained tantalum-niobium-tin mixed concentrate, and grind them using a ball mill. The grinding fineness is below 38 μm and the content is 70%.

[0088] (7) The finely ground tantalum-niobium-tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 0.8T to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained, and the filtrate is recycled to a water pool.

[0089] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate is recycled into the water return pool.

[0090] Example 2

[0091] like Figure 1 As shown, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0092] (1) Add lithium slag to recycled water and stir to make slurry with a mass concentration of 25%. Then, enter the spiral classifier for pre-classification to obtain coarse slurry and fine slurry with a classification particle size of 100μm.

[0093] (2) The coarse-grained slurry was disposed of by a waterfall chute to obtain coarse-grained tailings concentrate and coarse-grained tailings. The tailings removal rate was 70%.

[0094] (3) The fine-grained slurry was subjected to tailings removal using a blanket mill to obtain fine-grained tailings concentrate and fine-grained tailings. The tailings removal rate was 85%.

[0095] (4) The coarse-grained tailings concentrate is subjected to gravity separation by a composite bed shaking table to obtain coarse-grained tantalum-niobium-tin mixed concentrate, shaking table coarse-grained middlings and shaking table coarse-grained tailings. The shaking table coarse-grained middlings is ground by a ball mill to a content of 85% below 74μm and then returned to the blanket machine for tailings disposal.

[0096] (5) Fine-grained tailings concentrate is subjected to ore slime type shaking table gravity separation to obtain fine-grained tantalum-niobium-tin mixed concentrate, fine-grained middlings and fine-grained tailings; fine-grained middlings are returned to the blanket machine tailings disposal operation.

[0097] (6) Combine coarse-grained tantalum-niobium-tin mixed concentrate and fine-grained tantalum-niobium-tin mixed concentrate, and grind them using a vertical mill. The grinding fineness is below 38 μm and the content is 75%.

[0098] (7) The finely ground tantalum-niobium-tin mixed concentrate is subjected to strong magnetic separation using a drum-type strong magnetic separator with a magnetic field strength of 1.0T to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained, and the filtrate is recycled to a water pool.

[0099] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate is recycled into the water return pool.

[0100] Example 3

[0101] like Figure 1 As shown, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0102] (1) Add lithium slag to recycled water and stir to make slurry with a mass concentration of 30%. Then, put it into a high-frequency vibrating screen for pre-classification to obtain coarse slurry and fine slurry with a classification particle size of 150μm.

[0103] (2) The coarse-grained slurry is disposed of by spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings. The tailings removal rate is 50%.

[0104] (3) The fine-grained slurry is subjected to tailings removal operation using a blanket mill to obtain fine-grained tailings concentrate and fine-grained tailings. The tailings removal rate is 90%.

[0105] (4) The coarse-grained tailings concentrate is subjected to ore sand shaking table gravity separation to obtain coarse-grained tantalum-niobium-tin mixed concentrate, shaking table coarse-grained middlings and shaking table coarse-grained tailings. The shaking table coarse-grained middlings is ground by ball mill to a content of 90% below 74μm and then returned to the blanket machine tailings disposal operation.

[0106] (5) Fine-grained tailings concentrate is subjected to ore slime type shaking table gravity separation to obtain fine-grained tantalum-niobium-tin mixed concentrate, fine-grained middlings and fine-grained tailings; fine-grained middlings are returned to the blanket machine tailings disposal operation.

[0107] (6) Combine coarse-grained tantalum-niobium-tin mixed concentrate and fine-grained tantalum-niobium-tin mixed concentrate, and grind them using a vertical mill. The grinding fineness is below 38 μm and the content is 80%.

[0108] (7) The finely ground tantalum-niobium-tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.2T to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained, and the filtrate is recycled to a water pool.

[0109] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate is recycled into the water return pool.

[0110] Example 4

[0111] like Figure 1 As shown, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0112] (1) Lithium slag is added to recycled water and stirred to make slurry with a mass concentration of 35%. Then it is fed into a hydrocyclone for pre-classification to obtain coarse slurry and fine slurry with a classification particle size of 74 μm.

[0113] (2) The coarse-grained slurry is disposed of by spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings. The tailings removal rate is 80%.

[0114] (3) The fine-grained slurry is subjected to tailings removal operation using a blanket mill to obtain fine-grained tailings concentrate and fine-grained tailings. The tailings removal rate is 90%.

[0115] (4) The coarse-grained tailings concentrate is subjected to ore shaking table gravity separation to obtain coarse-grained tantalum-niobium-tin mixed concentrate, shaking table coarse-grained middlings and shaking table coarse-grained tailings. The shaking table coarse-grained middlings is ground by ball mill to a content of 95% below 74μm, and then returned to the blanket machine for tailings disposal.

[0116] (5) Fine-grained tailings concentrate is subjected to gravity separation using a composite bed shaking table to obtain fine-grained tantalum-niobium-tin mixed concentrate, fine-grained middlings and fine-grained tailings; the fine-grained middlings are returned to the blanket machine tailings disposal operation.

[0117] (6) Combine coarse-grained tantalum-niobium-tin mixed concentrate and fine-grained tantalum-niobium-tin mixed concentrate, and grind them using a tower mill. The grinding fineness is below 38 μm and the content is 85%.

[0118] (7) The finely ground tantalum-niobium-tin mixed concentrate is subjected to strong magnetic separation using a belt-type strong magnetic separator with a magnetic field strength of 1.0T to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained, and the filtrate is recycled to a water pool.

[0119] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate is recycled into the water return pool.

[0120] Example 5

[0121] like Figure 1 As shown, the method for comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0122] (1) Lithium slag is added to recycled water and stirred to make slurry with a mass concentration of 40%. Then it is fed into a hydrocyclone for pre-classification to obtain coarse slurry and fine slurry with a classification particle size of 74 μm.

[0123] (2) The coarse-grained slurry is disposed of by spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings. The tailings removal rate is 80%.

[0124] (3) The fine-grained slurry is subjected to tailings removal operation using a blanket mill to obtain fine-grained tailings concentrate and fine-grained tailings. The tailings removal rate is 90%.

[0125] (4) The coarse-grained tailings concentrate is subjected to ore shaking table gravity separation to obtain coarse-grained tantalum-niobium-tin mixed concentrate, shaking table coarse-grained middlings and shaking table coarse-grained tailings. The shaking table coarse-grained middlings is ground by ball mill to a content of 90% below 74μm and then returned to the blanket mill tailings operation.

[0126] (5) Fine-grained tailings concentrate is subjected to ore slime type shaking table gravity separation to obtain fine-grained tantalum-niobium-tin mixed concentrate, fine-grained middlings and fine-grained tailings; fine-grained middlings are returned to the blanket machine tailings disposal operation.

[0127] (6) Combine coarse-grained tantalum-niobium-tin mixed concentrate and fine-grained tantalum-niobium-tin mixed concentrate, and grind them using a ball mill. The grinding fineness is below 38 μm and the content is 90%.

[0128] (7) The finely ground tantalum-niobium-tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.2T to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained, and the filtrate is recycled to a water pool.

[0129] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate is recycled into the water return pool.

[0130] Comparative Example 1

[0131] A method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0132] (1) Add lithium slag to clean water and stir to make a slurry with a mass concentration of 30%;

[0133] (2) The slurry is subjected to high gradient strong magnetic separation for tailings removal. The magnetic field strength is 1.5T, and magnetic concentrate and magnetic tailings are obtained. The yield of magnetic tailings is 80%.

[0134] (3) The magnetic concentrate is subjected to gravity separation using a composite bed shaking table to obtain a tantalum-niobium-tin mixed concentrate, middlings and tailings. The middlings are returned to the magnetic separation tailings disposal operation.

[0135] (4) The tantalum-niobium-tin mixed concentrate was subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.0T to obtain tantalum-niobium concentrate and tin concentrate respectively.

[0136] Comparative Example 2

[0137] A method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0138] (1) Add lithium slag to clean water and stir to make a slurry with a mass concentration of 30%;

[0139] (2) Pump the slurry into the flotation machine, add 200g / t of styrene-phosphoric acid, a tantalum-niobium flotation reagent, and carry out tantalum-niobium flotation using a process of 1 roughing, 2 scavenging, and 3 cleaning. The flotation froth product is tantalum-niobium-tin rough concentrate, and the flotation underflow is tailings.

[0140] (3) Tantalum-niobium rough concentrate is subjected to gravity separation using a composite bed shaking table to obtain tantalum-niobium-tin concentrate, middlings and tailings. The middlings are returned to the flotation operation.

[0141] (4) The tantalum-niobium-tin mixed concentrate was subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.0T to obtain tantalum-niobium concentrate and tin concentrate respectively.

[0142] Comparative Example 3

[0143] A method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0144] (1) Add lithium slag to clean water and stir to make a slurry with a mass concentration of 30%;

[0145] (2) The slurry is subjected to tailings disposal using a spiral chute to obtain tailings concentrate and tailings, with a tailings disposal rate of 80%.

[0146] (3) The tailings concentrate is subjected to gravity separation using a composite bed shaking table to obtain tantalum-niobium-tin mixed concentrate, shaking table middlings and shaking table tailings. The shaking table middlings are ground by ball mill to a content of 80% below 74μm, and then returned to the spiral chute for tailings disposal.

[0147] (4) The tantalum-niobium-tin mixed concentrate was subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.0T to obtain tantalum-niobium concentrate and tin concentrate respectively.

[0148] Comparative Example 4

[0149] A method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag includes the following implementation steps:

[0150] (1) Add lithium slag to clean water and stir to make a slurry with a mass concentration of 30%;

[0151] (2) The slurry is subjected to tailings disposal using a spiral chute to obtain tailings concentrate and tailings, with a tailings disposal rate of 80%.

[0152] (3) The tailings concentrate is subjected to gravity separation using a composite bed shaking table to obtain tantalum-niobium-tin mixed concentrate, shaking table middlings and shaking table tailings. The shaking table middlings are ground by ball mill to a content of 80% below 74μm, and then returned to the spiral chute for tailings disposal.

[0153] (4) The tantalum-niobium-tin mixed concentrate is ground using a vertical mill to achieve a grinding fineness of less than 38 μm and a content of 90%.

[0154] (5) The finely ground tantalum-niobium-tin mixed concentrate was subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.0T to obtain tantalum-niobium concentrate and tin concentrate respectively.

[0155] The component content and recovery rate of tantalum-niobium and tin concentrates obtained from the examples and comparative examples were determined, and the results are shown in Table 2.

[0156] Table 2. Tantalum, Niobium, and Tin Specifications for Examples and Comparative Examples

[0157]

[0158] A comparison of Examples 1-5 with Comparative Example 1 shows that gravity separation tailings disposal achieves a higher tin recovery rate than magnetic separation tailings disposal. Magnetic separation tailings disposal results in greater tin loss during the process because some cassiterite in the lithium slag is non-magnetic. The tantalum and niobium recovery rates are also lower with magnetic separation tailings disposal.

[0159] A comparison of Examples 1-5 with Comparative Example 2 shows that the recovery rates of tantalum, niobium, and tin using the flotation process for optimized enrichment are much lower than those in the examples. The main reason is that lithium slag is a product of spodumene after high-temperature roasting and acid leaching for lithium extraction. After lithium extraction, the physicochemical properties of the tantalum, niobium, and tin mineral surfaces change, resulting in a lower flotation recovery rate.

[0160] Through Examples 1-5 and Comparative Example 3, tin was separated from tantalum-niobium-tin concentrate by fine grinding and magnetic separation, which can reduce the mutual content of tantalum-niobium and tin in tantalum-niobium concentrate and tin concentrate, and obtain tantalum-niobium concentrate with Sn < 5% and tin concentrate with Ta2O5 < 3%.

[0161] A comparison of Examples 1-5 with Comparative Example 4 shows that the recovery rate of tantalum-niobium-tin mixed concentrate can be increased by 5-10% by using a pre-classification and then gravity separation tailings disposal process compared to the unclassified direct tailings disposal process in Comparative Example 4.

Claims

1. A method for the comprehensive recovery of tantalum, niobium, and tin from lithium slag, wherein the lithium slag is a product of spodumene after high-temperature roasting and acid leaching for lithium extraction, characterized in that: Includes the following steps: S1. Pulping: Mix water and lithium slag to obtain slurry; S2. Grading: The slurry from step S1 is graded to obtain coarse-grained and fine-grained slurries; the particle size of the graded slurry is 74μm~150μm. S3. Tailings removal from coarse-grained slurry: The coarse-grained slurry from step S2 is subjected to tailings removal to obtain coarse-grained tailings concentrate and coarse-grained tailings; the tailings removal rate is 20%–98%. S4. Fine-grained slurry tailings removal: The fine-grained slurry obtained in step S2 is subjected to tailings removal to obtain fine-grained tailings concentrate and fine-grained tailings; the tailings removal rate is 20% to 98%. S5. Gravity separation of coarse-grained tailings concentrate: The coarse-grained tailings concentrate described in step S3 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate A, gravity concentrate A and gravity tailings A. S6. Gravity separation of fine-grained tailings concentrate: The fine-grained tailings concentrate described in step S4 is subjected to tantalum-niobium-tin gravity separation to obtain gravity concentrate B, gravity concentrate B and gravity tailings B. S7. Concentrate merging: Merge gravity concentrate A from step S5 and gravity concentrate B from step S6 to obtain a tantalum-niobium-tin mixed concentrate. The obtained tantalum-niobium-tin mixed concentrate is ground and subjected to strong magnetic separation to obtain tantalum-niobium concentrate and tin concentrate; the magnetic field strength of the strong magnetic separation is 0.3T to 1.5T. S8. Gravity-selected ore A processing: The gravity-selected ore A described in step S5 is concentrated and ground, and then returned to step S4 for tailings removal; the content of the ore with a grinding fineness of less than 74 μm is 50% to 100%; S9. Re-selecting Ore B: Return the re-selected ore B described in step S6 to step S4 for tailings disposal.

2. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 1, characterized in that: In step S1, the mass concentration of the slurry is 10% to 60%. In step S2, the equipment used for grading includes one or a combination of hydrocyclones, high-frequency vibrating fine screens, and spiral classifiers. In step S3, the equipment used for tailings disposal includes one or a combination of spiral sluices, blanket mills, fabric sluices, and jigs; the tailings removal rate is 50%–90%. In step S4, the equipment used for tailings disposal includes one or a combination of spiral sluices, blanket mills, fabric sluices, and jigs; the tailings removal rate is 50%–90%. In steps S5 and S6, the equipment used for gravity separation includes one or more combinations of composite bed shaking tables, fine sand shaking tables, slime shaking tables, suspended cone concentrators, and centrifuges.

3. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 2, characterized in that: In step S1, the mass concentration of the slurry is 20% to 40%.

4. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 1, characterized in that: In step S8, the equipment used for concentration includes one or more combinations of hydrocyclones, thickeners, and slurries; grinding includes one or more combinations of ball mills, vertical mills, and tower mills; and the content of the grinding fineness below 74 μm is 80% to 95%.

5. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 1, characterized in that: Specifically, the following steps are included: S10. Grinding: Grind the tantalum-niobium-tin mixed concentrate to obtain fine-grained tantalum-niobium-tin mixed concentrate; S11. Strong magnetic separation: The fine-grained tantalum-niobium-tin mixed concentrate described in step S10 is subjected to strong magnetic separation to obtain magnetic and non-magnetic materials respectively. After filtration, tantalum-niobium concentrate and tin concentrate are obtained respectively. The filtrate enters the water recycling tank for recycling. S12. Tailings treatment: The coarse-grained tailings, fine-grained tailings, gravity separation tailings A and gravity separation tailings B are combined and filtered. The filter residue is used as the total tailings, and the filtrate is recycled into the water return pool.

6. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 5, characterized in that: In step S10, grinding includes one or a combination of ball milling, vertical milling, and tower milling; the fineness of the ground ore is below 38 μm and the content is 30-95%. In step S11, the equipment used for strong magnetic separation includes one or a combination of high gradient magnetic separators, drum magnetic separators, and belt magnetic separators; the magnetic field strength of the strong magnetic separation is 0.8T to 1.2T. In steps S11 and S12, the equipment used for filtration includes one or a combination of ceramic filters, disc filters, and plate and frame filter presses.

7. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 6, characterized in that: In step S10, the content of ore with a fineness of less than 38 μm is 70% to 90%.

8. The method for comprehensive recovery of tantalum, niobium, and tin from lithium slag according to claim 5, characterized in that: In steps S11 and S12, the recycling rate of the recycled water is 100%.

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