Method for comprehensively recovering tantalum, niobium and tin from lithium slag

Abstract

The invention relates to a comprehensive recovery method of lithium slag, in particular to a method for recovering tantalum, niobium and tin rare metal elements from the lithium slag, and belongs to the technical field of lithium slag recovery. The technical problem to be solved by the invention is to provide the method for comprehensively recovering tantalum, niobium and tin from the lithium slag with high recovery rate. According to the method, the lithium slag is firstly subjected to pulping, grading and tailing discarding, and then the tantalum-niobium-tin concentrate is obtained through the steps of gravity separation, ore grinding and magnetic separation according to different particle fractions, so that the ore separation cost can be greatly reduced, the separation efficiency is improved, the loss of micro-fine particle fraction tantalum-niobium-tin minerals in tailings can be reduced, and the recovery rate of tantalum, niobium and tin is improved. And the concentrates subjected to graded tailing discarding are subjected to gravity separation by adopting different table surface differentiated shakers according to different particle sizes, so that the grade and the recovery rate of the tantalum-niobium-tin concentrates can be greatly improved, and the loss rate of fine-fraction tantalum-niobium-tin minerals in the tailings subjected to gravity separation by the shakers is reduced. According to the method, tantalum, niobium and tin can be effectively separated, high-quality tantalum-niobium concentrate and tin concentrate are obtained, and the recovery rate is high.

Description

Technical Field

[0001] The invention relates to a comprehensive recovery method of lithium slag, in particular to a method for recovering rare metal elements such as tantalum, niobium and tin from lithium slag, belonging to the technical field of lithium slag recovery. Background Art

[0002] Spodumene is an important lithium mineral, the main component of which is lithium aluminum silicate, usually accompanied by valuable metals such as tantalum, niobium, and tin. With the widespread application of lithium-ion batteries, the demand for lithium has increased significantly, and the lithium extraction technology of spodumene has also developed rapidly. Spodumene lithium extraction produces 8 to 10 tons of lithium slag for every ton of lithium carbonate produced. Based on the current lithium salt production capacity, more than 5 million tons of spodumene smelting slag are produced in China each year, and the (Ta+Nb)2O5 content in lithium slag is 100 to 180 ppm, and the Sn content is 100 to 200 ppm. Although the content of tantalum, niobium, and tin in lithium slag is low, if the rare metals tantalum, niobium, and tin can be recovered economically and efficiently, it still has high economic value.

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

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

[0005] Components <![CDATA[SO3]]> <![CDATA[Fe2O3]]> <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[Li2O]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> CaO 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] According to the research on lithium slag process mineralogy, the content of tantalum, niobium and tin in lithium slag is low, and tantalum, niobium and tin are dispersed in minerals of various particle sizes. About 30% of tantalum, niobium and tin minerals are distributed in minerals of particle size below 20μm, and most of the tantalum, niobium and tin minerals in lithium slag are wrapped in glass phase or connected with glass. This is one of the main differences between lithium slag and native tantalum, niobium and tin ore. The complex embedding characteristics of tantalum, niobium and tin minerals in lithium slag are the main reason why it is difficult to recover tantalum, niobium and tin metals from lithium slag.

[0007] For the recovery of valuable metals in lithium slag, the existing technology mainly adopts methods such as wet leaching and pyrometallurgy. Wet leaching is to contact lithium slag with leaching agents such as acid or alkali to dissolve valuable metals in the solution, and then recover valuable metals through extraction, precipitation and other processes. Pyrometallurgy is to melt lithium slag at high temperature, and then recover valuable metals by electrolysis or other methods. Problems of the prior art: There are still some problems with the existing technology for recovering valuable metals from lithium slag. First, the existing methods such as wet leaching and pyrometallurgy usually require a large amount of chemical reagents and energy, which are costly and difficult to achieve large-scale industrial application. Secondly, these methods may generate a large amount of wastewater and waste gas in the process of recovering valuable metals, causing pollution to the environment. Finally, due to the low content of low-content valuable metals in lithium slag, conventional mineral processing methods are also difficult to achieve efficient recovery, which often leads to low recovery rate of valuable metals and serious waste of resources. Therefore, how to recover low-content valuable metals in lithium slag at low cost and environmentally friendly is a problem that needs to be solved urgently in this field.

[0008] Patents CN113976309A, CN117065916A, CN117165787A, and CN116532235A all involve the recycling of rare metals tantalum and niobium in lithium slag, and mainly use magnetic separation + gravity separation process for recovery. Patent CN114226413A discloses a method for recovering tantalum and niobium from lithium slag using flotation + gravity separation. The tantalum and niobium recovery rate using the processes in the above patents is low, and fine-grained tantalum and niobium are difficult to recover. There is no separation and recovery of tin, resulting in a waste of tin resources and difficulty in obtaining high-quality tantalum and niobium concentrates. At the same time, due to the extremely low content of rare metals tantalum, niobium and tin in the raw materials, the raw materials are directly enriched in tantalum and niobium by magnetic separation or flotation, which results in a large processing volume, high sorting costs, and poor economic efficiency. Summary of the invention

[0009] In view of the above defects, the technical problem solved by the present invention is to provide a method for comprehensively recovering tantalum, niobium and tin from lithium slag with a high recovery rate.

[0010] The method for comprehensively recovering tantalum, niobium and tin from lithium slag of the present invention comprises the following steps: firstly slurrying the lithium slag and then classifying it to obtain coarse-grained slurry and fine-grained slurry, and then respectively discarding tailings and reselecting the coarse-grained slurry and the fine-grained slurry to obtain a tantalum, niobium and tin mixed concentrate.

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

[0012] S1. Slurrying: mixing water and lithium slag to obtain slurry;

[0013] S2, classification: Classifying the slurry in step S1 to obtain coarse-grained and fine-grained slurries respectively;

[0014] S3, coarse-grained slurry tailings disposal: the coarse-grained slurry described in step S2 is subjected to tailings disposal to obtain coarse-grained tailings concentrate and coarse-grained tailings;

[0015] S4, fine-grained slurry tailings disposal: the fine-grained slurry described in step S2 is subjected to tailings disposal to obtain fine-grained tailings concentrate and fine-grained tailings disposal;

[0016] S5, coarse-grained tailings concentrate gravity separation: the coarse-grained tailings concentrate described in step S3 is subjected to tantalum, niobium and tin gravity separation to obtain gravity separation concentrate A, gravity separation ore A and gravity separation tailings A;

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

[0018] S7. Concentrate merging: The gravity-separated concentrate A described in step S5 and the gravity-separated concentrate B described in step S6 are combined to obtain a tantalum, niobium and 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 classification includes one or a combination of a hydrocyclone, a high-frequency vibrating fine screen, and a spiral classifier; and the classified particle size is 74 μm to 150 μm.

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

[0022] In some embodiments of the present invention, in step S4, the equipment used for tailings removal includes one or a combination of a spiral chute, a blanket machine, a spreading chute, and a jig. In some embodiments of the present invention, the tailings removal rate of step S4 is 20% to 98%. In some specific embodiments, the tailings removal rate of step S4 is 50% to 90%. In steps S5 and S6, the equipment used for gravity separation includes one or a combination of a composite bed shaking table, a fine sand shaking table, a sludge shaking table, a suspended vibration cone concentrator, and a centrifuge.

[0023] In some embodiments of the present invention, in step S5 and step S6, the equipment used for gravity separation includes one or a combination of a composite bed shaking table, a fine sand shaking table, a sludge shaking table, a suspended vibration cone concentrator, and a centrifuge.

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

[0025] S8, treatment of the gravity separation ore A: concentrating and grinding the gravity separation ore A described in step S5, and returning the ground ore to step S4 for tailings discarding;

[0026] S9, processing of the re-selected ore B: returning the re-selected ore B described in step S6 to step S4 for tailings discarding.

[0027] In one embodiment of the present invention, in step S8, the equipment used for concentration includes one or a combination of a cyclone, a concentrator, and a thickener; the grinding includes one or a combination of ball grinding, vertical grinding, and tower grinding; 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 comprises grinding and magnetic separation of the obtained tantalum, niobium and tin mixed concentrate to obtain tantalum, niobium 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 comprises the following steps:

[0030] S10, grinding: grinding the tantalum, niobium and tin mixed concentrate described in step S7 to obtain a fine-grained tantalum, niobium and tin mixed concentrate;

[0031] S11, magnetic separation: subjecting the fine-grained tantalum, niobium and tin mixed concentrate described in step S10 to strong magnetic separation to obtain magnetic material and non-magnetic material respectively, and filtering to obtain tantalum and niobium concentrate and tin concentrate respectively, and the filtrate enters the return water pool 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, and the filter residue is used as the total tailings. The filtrate enters the recycle pool for recycling.

[0033] In a specific embodiment, in step S10, the grinding includes one or a combination of ball milling, vertical milling, and tower milling. In one embodiment of the present invention, the grinding fineness is below 38 μm and the content is 30-95%. In a preferred embodiment, the grinding fineness is below 38 μm and the content is 70%-90%.

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

[0035] In a specific embodiment, in step S11 and step S12, the filtering equipment used includes one or a combination of ceramic filter, disc filter, plate and frame filter press.

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

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

[0038] The method of the present invention first pulps, classifies and discards the lithium slag, and then obtains the tantalum, niobium and tin concentrate through gravity separation, grinding and magnetic separation steps. The lithium slag is pre-classified and then discarded. Different tailings discarding equipment is selected for different particle sizes, which can not only greatly reduce the amount of ore to be selected during deep enrichment of tantalum, niobium and tin, thereby reducing the cost of mineral processing and improving the sorting efficiency, but also reduce the loss of fine-grained tantalum, niobium and tin minerals in the tailings and improve the recovery rate of tantalum, niobium and tin. Differentiated shaking tables with different bed surfaces are used for gravity separation of the concentrate after classification and tailings according to different particle sizes, which can greatly improve the grade and recovery rate of the 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.

[0039] The method of the present invention can effectively separate tantalum, niobium and tin, so that the Sn content in the tantalum-niobium concentrate is less than 5%, the Ta2O5 in the tin concentrate is less than 3%, and the tantalum-niobium content (calculated as oxide) is less than 5%; the method of the present invention can obtain relatively high-quality tantalum-niobium concentrate and tin concentrate with high recovery rate, the Ta2O5 grade of the tantalum-niobium concentrate is ≥20%, and the tantalum recovery rate is ≥60%; the Nb2O5 grade is ≥14%, and the niobium recovery rate is ≥55%; the Sn grade of the tin concentrate is ≥55%, and the tin recovery rate is ≥60%. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] The method for comprehensively recovering tantalum, niobium and tin from lithium slag of the present invention comprises the following steps: firstly slurrying the lithium slag and then classifying it to obtain coarse-grained slurry and fine-grained slurry, and then respectively discarding tailings and reselecting the coarse-grained slurry and the fine-grained slurry to obtain a tantalum, niobium and tin mixed concentrate.

[0042] The method of the present invention adopts pre-classification before tailings disposal. Different tailings disposal equipment can be used for materials of different coarse and fine particle sizes to carry out efficient tailings disposal. Firstly, the processing volume of the subsequent re-selection process can be greatly reduced, and the separation efficiency of tantalum, niobium and tin can be improved. Secondly, according to the different particle sizes of the minerals, the tailings disposal equipment suitable for the tailings disposal can be used to significantly reduce the loss rate of tantalum, niobium and tin metals in the tailings disposal. The loss rates of tantalum, niobium and tin metals in the tailings disposal are both less than 15%. If the lithium slag is not pre-classified and tailings disposal is not carried out in advance, the loss rate of fine-grained tantalum, niobium and tin minerals in the tailings disposal stage will be large, and the overall recovery rate of tantalum, niobium and tin will be as low as 5-10%. The main reason is that the tantalum, niobium and tin minerals have a low content and are dispersed in various particle sizes of the lithium slag. In the tailings disposal process, the fine-grained tantalum, niobium and tin minerals are easily discarded together with the coarse-grained gangue minerals.

[0043] In addition, the concentrate after classification and tailings can be re-selected by using different bed surfaces according to different particle sizes, which can greatly improve the grade and recovery rate of tantalum, niobium and tin concentrates and reduce the loss rate of fine-grained tantalum, niobium and tin minerals in the tailings of the re-selection table. If the coarse and fine-grained differentiated re-selection table is not carried out, the fine-grained tantalum, niobium and tin minerals and the coarse-grained gangue minerals cannot form zoning and enter the tailings of the shaking table and are lost.

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

[0045] S1. Slurrying: mixing water and lithium slag to obtain slurry;

[0046] S2, classification: Classifying the slurry in step S1 to obtain coarse-grained and fine-grained slurries respectively;

[0047] S3, coarse-grained slurry tailings disposal: the coarse-grained slurry described in step S2 is subjected to tailings disposal to obtain coarse-grained tailings concentrate and coarse-grained tailings;

[0048] S4, fine-grained slurry tailings disposal: the fine-grained slurry described in step S2 is subjected to tailings disposal to obtain fine-grained tailings concentrate and fine-grained tailings disposal;

[0049] S5, coarse-grained tailings concentrate gravity separation: the coarse-grained tailings concentrate described in step S3 is subjected to tantalum, niobium and tin gravity separation to obtain gravity separation concentrate A, gravity separation ore A and gravity separation tailings A;

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

[0051] S7. Concentrate merging: The gravity-separated concentrate A described in step S5 and the gravity-separated concentrate B described in step S6 are combined to obtain a tantalum, niobium and tin mixed concentrate.

[0052] Step S1 is slurrying, mixing water and lithium slag to obtain slurry. Clean water or recycled water can be mixed with lithium slag and stirred to make slurry. In one embodiment of the present invention, the mass concentration of the slurry is 10% to 60%. In some specific embodiments, the mass concentration of the slurry is 20% to 40%.

[0053] Step S2 is classification: the slurry in step S1 is classified to obtain coarse-grained and fine-grained slurries respectively. In this step, the classification can be carried out by using one or a combination of a hydrocyclone, a high-frequency vibrating fine screen, and a spiral classifier.

[0054] In some embodiments of the present invention, the graded particle size is 74 μm to 150 μm. That is, the graded particle size can be any value between 74 μm and 150 μm as the graded standard. For example, the graded particle size is 74 μm, that is, particles with a particle size greater than or equal to 74 μm are coarse particles, and particles less than 74 μm are fine particles; for another example, the graded particle size is 150 μm, that is, particles with a particle size greater than or equal to 150 μm are coarse particles, and particles less than 150 μm are fine particles; for another example, the graded particle size is 100 μm. μm, that is, particles with a size greater than or equal to 100μm are coarse particles, and particles less than 100μm are fine particles, and so on. The graded particle size can be 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm and so on.

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

[0056] 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 machine, a cloth chute, and a jig. In some embodiments of the present invention, the tailings removal rate of the tailings removal in step S3 is 20% to 98%. In some specific embodiments, the tailings removal rate of the tailings removal in step S3 is 50% to 90%.

[0057] Step S4 is the fine-grained slurry tailings disposal, and the fine-grained slurry described in step S2 is subjected to tailings disposal to obtain fine-grained tailings concentrate and fine-grained tailings.

[0058] The tailings removal rate of step S4, the equipment used and the specific tailings removal rate can be the same as or different from those of step S3. In some embodiments of the present invention, the equipment used for tailings removal in step S4 includes one or more combinations of spiral chute, blanket machine, cloth chute, and jig. In some embodiments of the present invention, the tailings removal rate of step S4 is 20% to 98%. In some specific embodiments, the tailings removal rate of step S4 is 50% to 90%.

[0059] Step S5 is the coarse-grained tailings concentrate re-selection, and the coarse-grained tailings concentrate described in step S3 is re-selected for tantalum, niobium and tin to obtain re-selection concentrate A, re-selection ore A and re-selection tailings A. In some embodiments of the present invention, the equipment used for re-selection in step S5 includes one or a combination of a composite bed shaking table, a fine sand shaking table, a sludge shaking table, a suspended cone concentrator and a centrifuge.

[0060] Step S6 is the re-selection of the fine-grained tailings concentrate, and the fine-grained tailings concentrate described in step S4 is re-selected for tantalum, niobium and tin to obtain re-selection concentrate B, re-selection ore B and re-selection tailings B. In some embodiments of the present invention, the equipment used for the re-selection in step S6 includes one or a combination of a composite bed shaking table, a fine sand shaking table, a sludge shaking table, a suspended cone concentrator and a centrifuge.

[0061] Step S7 is to combine the concentrates, combining the re-selected concentrate A described in step S5 and the re-selected concentrate B described in step S6 to obtain a tantalum, niobium and 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 comprises at least one of the following steps:

[0063] S8, treatment of the gravity separation ore A: concentrating and grinding the gravity separation ore A described in step S5, and returning the ground ore to step S4 for tailings discarding;

[0064] S9, processing of the re-selected ore B: returning the re-selected ore B described in step S6 to step S4 for tailings discarding.

[0065] Part of the resources can be recovered by processing the gravity separation ore A or gravity separation ore B. Among them, step S8 is the processing of gravity separation ore A, and step S9 is the processing of gravity separation ore B. In one embodiment of the present invention, in step S8, the equipment used for concentration includes one or several combinations of cyclone, concentrator, and thickener; grinding includes one or several combinations of ball milling, vertical milling, and tower milling; the content of minerals with a grinding fineness of less than 74μm is 50% to 100%, and in a preferred embodiment, the content of minerals with a grinding fineness of less than 74μm is 80% to 95%.

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

[0068] S10, grinding: grinding the tantalum, niobium and tin mixed concentrate described in step S7 to obtain a fine-grained tantalum, niobium and tin mixed concentrate;

[0069] S11, magnetic separation: subjecting the fine-grained tantalum, niobium and tin mixed concentrate described in step S10 to strong magnetic separation to obtain magnetic material and non-magnetic material respectively, and filtering to obtain tantalum and niobium concentrate and tin concentrate respectively, and the filtrate enters the return water pool 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, and the filter residue is used as the total tailings. The filtrate enters the recycle pool for recycling.

[0071] Through the steps S10 to S12, tantalum-niobium concentrate and tin concentrate can be recovered from the tantalum-niobium-tin mixed concentrate. Since the lithium slag is quite different from the primary ore, most of the tantalum-niobium-tin minerals in the lithium slag are wrapped or co-existed by glass phase materials. After direct magnetic separation, the tantalum-niobium-tin content in the concentrate is high. Since the tin in the tantalum-niobium concentrate and the tantalum-niobium in the tin concentrate cannot be priced separately, resulting in resource loss, the fine grinding-strong magnetic process proposed in the present invention 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 less than 5%, and the Ta2O5 in the tin concentrate is less than 3%.

[0072] Step S10 is grinding, grinding the tantalum, niobium and tin mixed concentrate described in step S7 to obtain a fine-grained tantalum, niobium and tin mixed concentrate. The grinding methods commonly used in the art are suitable for the present invention. In a specific embodiment, the grinding includes one or more combinations of ball milling, vertical milling and tower milling. In one embodiment of the present invention, the fineness of the grinding is below 38 μm and the content is 30-95%. In a preferred embodiment, the fineness of the grinding is below 38 μm and the content is 70%-90%.

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

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

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

[0076] The filtration in step S11 may also be carried out by conventional filtration methods in the art. In some specific embodiments, the equipment used for filtration includes one or a combination of a ceramic filter, a disc filter, and a plate and frame filter press.

[0077] Step S12 is tailings treatment, where the coarse-grained tailings, fine-grained tailings, gravity-selected tailings A and gravity-selected tailings B are combined for filtration, and the filter residue is used as the total tailings, and the filtrate enters the return pool for recycling. The filtration in this step may be the same as or different from step S11. In some specific embodiments, the equipment used for filtration includes one or a combination of a ceramic filter, a disc filter, and a plate and frame filter press.

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

[0079] The specific implementation of the present invention is further described below in conjunction with the examples, but the present invention is not limited to the scope of the examples. 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 comprises the following implementation steps:

[0082] (1) adding lithium slag to clean water for stirring and slurrying to prepare a slurry with a mass concentration of 20%, and then entering a hydrocyclone for pre-classification to obtain a coarse-grained slurry and a fine-grained slurry with a classification particle size of 74 μm;

[0083] (2) The coarse-grained slurry is subjected to tailings disposal by using a spreading chute to obtain coarse-grained tailings concentrate and coarse-grained tailings, with a tailings disposal rate of 80%;

[0084] (3) Fine-grained slurry is subjected to tailings removal by a felt machine to obtain fine-grained tailings concentrate and fine-grained tailings, with a tailings removal rate of 80%;

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

[0086] (5) The fine-grained tailings concentrate is re-selected using a sludge-type shaking table to obtain a fine-grained tantalum-niobium-tin mixed concentrate, a fine-grained re-selected middling and a fine-grained tailings; the fine-grained middling is returned to the blanket machine for tailings disposal;

[0087] (6) combining the coarse-grained tantalum-niobium-tin mixed concentrate and the fine-grained tantalum-niobium-tin mixed concentrate, and grinding them with a ball mill, wherein the grinding fineness is less than 38 μm and the content is 70%;

[0088] (7) The ground tantalum, niobium and tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 0.8 T to obtain magnetic materials and non-magnetic materials respectively, and then filtered to obtain tantalum, niobium and tin concentrates, and the filtrate is reused in a water tank;

[0089] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate enters the recycle pool for reuse.

[0090] Example 2

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

[0092] (1) adding lithium slag to recycled water for stirring and slurrying to prepare a slurry with a mass concentration of 25%, and then entering a spiral classifier for pre-classification to obtain a coarse-grained slurry and a fine-grained slurry with a classification particle size of 100 μm;

[0093] (2) The coarse-grained slurry is subjected to tailings disposal by using a waterfall chute to obtain coarse-grained tailings concentrate and coarse-grained tailings, with a tailings disposal rate of 70%;

[0094] (3) Fine-grained slurry is subjected to tailings removal by a felt machine to obtain fine-grained tailings concentrate and fine-grained tailings, with a tailings removal rate of 85%;

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

[0096] (5) The fine-grained tailings concentrate is re-selected using a sludge-type shaking table to obtain a fine-grained tantalum-niobium-tin mixed concentrate, a fine-grained re-selected middling and a fine-grained tailings; the fine-grained middling is returned to the blanket machine for tailings disposal;

[0097] (6) combining the coarse-grained tantalum-niobium-tin mixed concentrate and the fine-grained tantalum-niobium-tin mixed concentrate, and grinding them with a vertical mill, with a grinding fineness of less than 38 μm and a content of 75%;

[0098] (7) The ground tantalum, niobium and tin mixed concentrate is subjected to strong magnetic separation using a drum-type strong magnetic separator with a magnetic field strength of 1.0 T to obtain magnetic materials and non-magnetic materials respectively, and then filtered to obtain tantalum, niobium and tin concentrates, and the filtrate is reused in a water tank;

[0099] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate enters the recycle pool for reuse.

[0100] Example 3

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

[0102] (1) adding lithium slag to recycled water for stirring and slurrying to prepare a slurry with a mass concentration of 30%, and then entering a high-frequency vibrating screen for pre-classification to obtain a coarse-grained slurry and a fine-grained slurry with a classification particle size of 150 μm;

[0103] (2) The coarse-grained slurry is subjected to tailings disposal by a spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings, with a tailings disposal rate of 50%;

[0104] (3) Fine-grained slurry is subjected to tailings removal by a felt machine to obtain fine-grained tailings concentrate and fine-grained tailings, with a tailings removal rate of 90%;

[0105] (4) The coarse-grained tailings concentrate is reselected by an ore sand shaking table to obtain a coarse-grained tantalum-niobium-tin mixed concentrate, a shaking table coarse-grained intermediate ore and a shaking table coarse-grained tailings. The shaking table coarse-grained intermediate ore is ground by a ball mill to a content of 90% below 74 μm, and then returned to the felt machine for tailings disposal;

[0106] (5) The fine-grained tailings concentrate is re-selected using a sludge-type shaking table to obtain a fine-grained tantalum-niobium-tin mixed concentrate, a fine-grained re-selected middling and a fine-grained tailings; the fine-grained middling is returned to the blanket machine for tailings disposal;

[0107] (6) combining the coarse-grained tantalum-niobium-tin mixed concentrate and the fine-grained tantalum-niobium-tin mixed concentrate, and grinding them with a vertical mill, with a grinding fineness of less than 38 μm and a content of 80%;

[0108] (7) The ground tantalum, niobium and tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.2 T to obtain magnetic materials and non-magnetic materials respectively, and then filtered to obtain tantalum, niobium and tin concentrates, and the filtrate is reused in a water tank;

[0109] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate enters the recycle pool for reuse.

[0110] Example 4

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

[0112] (1) adding lithium slag to recycled water for stirring and slurrying to prepare a slurry with a mass concentration of 35%, and then entering a hydrocyclone for pre-classification to obtain a coarse-grained slurry and a fine-grained slurry with a classification particle size of 74 μm;

[0113] (2) The coarse-grained slurry is subjected to tailings disposal by a spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings, with a tailings disposal rate of 80%;

[0114] (3) Fine-grained slurry is subjected to tailings removal by a felt machine to obtain fine-grained tailings concentrate and fine-grained tailings, with a tailings removal rate of 90%;

[0115] (4) The coarse-grained tailings concentrate is reselected by an ore sand shaking table to obtain a coarse-grained tantalum-niobium-tin mixed concentrate, a shaking table coarse-grained intermediate ore and a shaking table coarse-grained tailings. The shaking table coarse-grained intermediate ore is ground by a ball mill to a content of 95% below 74 μm, and then returned to the felt machine for tailings disposal;

[0116] (5) The fine-grained tailings concentrate is re-selected by a composite bed shaking table to obtain a fine-grained tantalum-niobium-tin mixed concentrate, a fine-grained re-selected middling and a fine-grained tailings; the fine-grained middling is returned to the blanket machine for tailings disposal;

[0117] (6) combining the coarse-grained tantalum-niobium-tin mixed concentrate and the fine-grained tantalum-niobium-tin mixed concentrate, and grinding them with a tower mill, with a grinding fineness of less than 38 μm and a content of 85%;

[0118] (7) The ground tantalum, niobium and tin mixed concentrate is subjected to strong magnetic separation using a belt-type strong magnetic separator with a magnetic field strength of 1.0 T to obtain magnetic materials and non-magnetic materials respectively, and then filtered to obtain tantalum, niobium and tin concentrates, and the filtrate is reused in a water tank;

[0119] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate enters the recycle pool for reuse.

[0120] Example 5

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

[0122] (1) adding lithium slag to recycled water for stirring and slurrying to prepare a slurry with a mass concentration of 40%, and then entering a hydrocyclone for pre-classification to obtain a coarse-grained slurry and a fine-grained slurry with a classification particle size of 74 μm;

[0123] (2) The coarse-grained slurry is subjected to tailings disposal by a spiral chute to obtain coarse-grained tailings concentrate and coarse-grained tailings, with a tailings disposal rate of 80%;

[0124] (3) Fine-grained slurry is subjected to tailings removal by a felt machine to obtain fine-grained tailings concentrate and fine-grained tailings, with a tailings removal rate of 90%;

[0125] (4) The coarse-grained tailings concentrate is reselected by an ore sand shaking table to obtain a coarse-grained tantalum-niobium-tin mixed concentrate, a shaking table coarse-grained intermediate ore and a shaking table coarse-grained tailings. The shaking table coarse-grained intermediate ore is ground by a ball mill to a content of 90% below 74 μm, and then returned to the felt machine for tailings disposal;

[0126] (5) The fine-grained tailings concentrate is re-selected using a sludge-type shaking table to obtain a fine-grained tantalum-niobium-tin mixed concentrate, a fine-grained re-selected middling and a fine-grained tailings; the fine-grained middling is returned to the blanket machine for tailings disposal;

[0127] (6) combining the coarse-grained tantalum-niobium-tin mixed concentrate and the fine-grained tantalum-niobium-tin mixed concentrate, and grinding them with a ball mill, wherein the grinding fineness is less than 38 μm and the content is 90%;

[0128] (7) The ground tantalum, niobium and tin mixed concentrate is subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field strength of 1.2 T to obtain magnetic materials and non-magnetic materials respectively, and then filtered to obtain tantalum, niobium and tin concentrates, and the filtrate is reused in a water tank;

[0129] (8) All tailings are combined and filtered to obtain total tailings, and the filtrate enters the recycle pool for reuse.

[0130] Comparative Example 1

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

[0132] (1) adding lithium slag to clean water and stirring to prepare slurry to form a slurry with a mass concentration of 30%;

[0133] (2) The slurry is subjected to high gradient strong magnetic separation for tailings removal, with a magnetic field strength of 1.5 T to obtain magnetic concentrate and magnetic tailings, with a yield of 80% for the magnetic tailings;

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

[0135] (4) The mixed tantalum, niobium and tin concentrates are subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field intensity of 1.0 T to obtain tantalum and niobium concentrates and tin concentrates, respectively.

[0136] Comparative Example 2

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

[0138] (1) adding lithium slag to clean water and stirring to prepare slurry to form a slurry with a mass concentration of 30%;

[0139] (2) Pumping the slurry into a flotation machine, adding 200 g / t of styrene phosphoric acid, a tantalum-niobium flotation agent, and adopting a 1-roughing-2-sweeping-3-fine process to carry out tantalum-niobium flotation. The flotation foam product is a tantalum-niobium-tin rough concentrate, and the flotation underflow is the tailings;

[0140] (3) The tantalum-niobium coarse concentrate is re-selected using a composite bed shaking table to obtain tantalum-niobium-tin concentrate, middlings and tailings, and the middlings are returned to the flotation operation;

[0141] (4) The mixed tantalum, niobium and tin concentrates are subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field intensity of 1.0 T to obtain tantalum and niobium concentrates and tin concentrates, respectively.

[0142] Comparative Example 3

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

[0144] (1) adding lithium slag to clean water and stirring to prepare slurry to form a slurry with a mass concentration of 30%;

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

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

[0147] (4) The mixed tantalum, niobium and tin concentrates are subjected to strong magnetic separation using a high gradient magnetic separator with a magnetic field intensity of 1.0 T to obtain tantalum and niobium concentrates and tin concentrates, respectively.

[0148] Comparative Example 4

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

[0150] (1) adding lithium slag to clean water and stirring to prepare slurry to form a slurry with a mass concentration of 30%;

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

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

[0153] (4) grinding the tantalum, niobium and tin mixed concentrate by a vertical mill, with a grinding fineness of less than 38 μm and a content of 90%;

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

[0155] The component contents of the tantalum-niobium concentrate and the tin concentrate obtained in the examples and comparative examples and the recovery rates of tantalum-niobium-tin were measured, and the results are shown in Table 2.

[0156] Table 2 Tantalum, niobium and tin indicators of the examples and comparative examples

[0157]

[0158] By comparing Examples 1 to 5 with Comparative Example 1, it can be seen that the gravity separation tailings can obtain a higher tin recovery rate than the magnetic separation tailings. The magnetic separation tailings, due to the non-magnetic nature of some cassiterite in the lithium slag, lead to a large loss of tin in the tailings. The magnetic separation tailings process also has a lower tantalum and niobium recovery rate.

[0159] By comparing Examples 1 to 5 with Comparative Example 2, it can be seen that the recovery rates of tantalum, niobium and tin are much lower than those of the embodiment when the flotation process is used for optimization and enrichment. The main reason is that lithium slag is the product of spodumene after high-temperature roasting and acid leaching of lithium. After lithium extraction, the physical and chemical properties of the surface of tantalum, niobium and tin minerals change, and the flotation recovery rate is low.

[0160] Through Examples 1 to 5 and Comparative Example 3, the tantalum-niobium-tin concentrate is finely ground and magnetically separated to separate tin, which can reduce the mutual content of tantalum-niobium and tin in the tantalum-niobium concentrate and tin concentrate, and obtain a tantalum-niobium concentrate with Sn < 5% and a tin concentrate with Ta2O5 < 3%.

[0161] By comparing Examples 1 to 5 with Comparative Example 4, it can be seen that the recovery rate of the tantalum, niobium and tin mixed concentrate can be increased by 5 to 10% by adopting the process of pre-classification and then gravity separation and tailings discarding, compared with the unclassified direct tailings discarding process in Comparative Example 4.

Claims

1. A method for comprehensive recovery of tantalum, niobium and tin from lithium slag, characterized by: The lithium slag is first pulped and then classified to obtain coarse-grained slurry and fine-grained slurry, and then the coarse-grained slurry and the fine-grained slurry are respectively subjected to tailings discarding and gravity separation to obtain a tantalum-niobium-tin mixed concentrate.

2. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 1, characterized in that: The specific steps include: S1. Slurrying: mixing water and lithium slag to obtain slurry; S2, classification: Classifying the slurry in step S1 to obtain coarse-grained and fine-grained slurries respectively; S3, coarse-grained slurry tailings disposal: the coarse-grained slurry described in step S2 is subjected to tailings disposal to obtain coarse-grained tailings concentrate and coarse-grained tailings; S4, fine-grained slurry tailings disposal: the fine-grained slurry described in step S2 is subjected to tailings disposal to obtain fine-grained tailings concentrate and fine-grained tailings disposal; S5, coarse-grained tailings concentrate gravity separation: the coarse-grained tailings concentrate described in step S3 is subjected to tantalum, niobium and tin gravity separation to obtain gravity separation concentrate A, gravity separation ore A and gravity separation tailings A; S6, gravity separation of fine-grained tailings concentrate: The fine-grained tailings concentrate described in step S4 is subjected to gravity separation of tantalum, niobium and tin to obtain gravity separation concentrate B, gravity separation ore B and gravity separation tailings B; S7. Concentrate merging: The gravity-separated concentrate A described in step S5 and the gravity-separated concentrate B described in step S6 are combined to obtain a tantalum, niobium and tin mixed concentrate.

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 10% to 60%; preferably, the mass concentration of the slurry is 20% to 40%; In step S2, the equipment used for classification includes one or a combination of a hydrocyclone, a high-frequency vibrating fine screen, and a spiral classifier; the particle size of the classification is 74 μm to 150 μm; In step S3, the equipment used for tailings removal includes one or a combination of a spiral chute, a blanket machine, a cloth chute, and a jig; the tailings removal rate of tailings removal is 20% to 98%; preferably, the tailings removal rate of tailings removal is 50% to 90%; In step S4, the equipment used for tailings removal includes one or a combination of a spiral chute, a blanket machine, a cloth chute, and a jig; the tailings removal rate of tailings removal is 20% to 98%; preferably, the tailings removal rate of tailings removal is 50% to 90%; In step S5 and step S6, the equipment used for gravity separation includes one or a combination of a composite bed shaking table, a fine sand shaking table, a sludge shaking table, a suspended vibration cone concentrator, and a centrifuge.

4. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 2, characterized in that: Also includes at least one of the following steps: S8, treatment of the gravity separation ore A: concentrating and grinding the gravity separation ore A described in step S5, and returning the ground ore to step S4 for tailings discarding; S9, processing of the re-selected ore B: returning the re-selected ore B described in step S6 to step S4 for tailings discarding.

5. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 4, characterized in that: In step S8, the equipment used for concentration includes one or a combination of a cyclone, a concentrator, and a thickener; the grinding includes one or a combination of ball grinding, vertical grinding, and tower grinding; the content of grinding fineness below 74 μm is 50% to 100%, and preferably the content below 74 μm is 80% to 95%.

6. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 1 or 2, characterized in that: The method also includes grinding and magnetically separating the obtained tantalum-niobium-tin mixed concentrate to obtain tantalum-niobium concentrate and tin concentrate.

7. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 6, characterized in that: The specific steps include: S10, grinding: grinding the tantalum, niobium and tin mixed concentrate to obtain a fine-grained tantalum, niobium and tin mixed concentrate; S11, magnetic separation: subjecting the fine-grained tantalum, niobium and tin mixed concentrate described in step S10 to strong magnetic separation to obtain magnetic material and non-magnetic material respectively, and filtering to obtain tantalum and niobium concentrate and tin concentrate respectively, and the filtrate enters the return water pool 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, and the filter residue is used as the total tailings. The filtrate enters the recycle pool for recycling.

8. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 7, characterized in that: In step S10, the grinding includes one or a combination of ball milling, vertical milling, and tower milling; the grinding fineness is below 38 μm and the content is 30-95%, preferably the grinding fineness is below 38 μm and the content is 70%-90%; In step S11, the equipment used for high-intensity magnetic separation includes one or a combination of high-gradient magnetic separator, drum magnetic separator, and belt magnetic separator; the magnetic field strength of the high-intensity magnetic separation is 0.3T to 1.5T, and preferably the magnetic field strength of the high-intensity magnetic separation is 0.8T to 1.2T; In step S11 and step S12, the filtering equipment used includes one or a combination of ceramic filter, disc filter, plate and frame filter press.

9. The method for comprehensive recovery of tantalum, niobium and tin from lithium slag according to claim 7, characterized in that: In steps S11 and S12, the recycling rate of the returned water is 100%.

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