Treatment method for coal gangue rich in lithium and gallium

Abstract

The invention discloses a treatment method for coal gangue rich in lithium and gallium, belongs to the technical field of coal series solid waste resource utilization, and aims to solve the problem of low resource utilization rate of coal gangue in the prior art. The method comprises the following steps: screening a coal gangue raw material; the oversize gangue is pre-sorted, and sorted concentrate rich in lithium and gallium and sorted tailings rich in iron are obtained; crushing the undersize gangue and the separated concentrate to obtain a crushed mixture; performing magnetic roasting on the crushed mixture to obtain a roasted product; carrying out magnetic separation on the roasted product to obtain magnetic separation tailings and iron-rich magnetic separation concentrate; mixing the magnetic separation tailings with a roasting auxiliary agent, and sequentially carrying out activating roasting, acid leaching and filtering to obtain leaching residues and lithium gallium leaching liquid; and separating and purifying the lithium-gallium leaching solution to obtain metal lithium and metal gallium. The method can be used for treating the coal gangue rich in lithium and gallium.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of coal-based solid waste, and in particular relates to a method for treating lithium-gallium-rich coal gangue. Background Art

[0002] my country has rich reserves of coal resources. A large amount of coal-based solid waste is generated during the mining and sorting process. Coal gangue is the largest type of solid waste. If it is not treated in time, it will not only cause huge pollution to the environment, but also waste the potential value contained in the coal gangue.

[0003] The main ways to utilize coal gangue are: direct backfill, combustion for power generation, as building materials, as chemical raw materials, and extraction of valuable elements.

[0004] However, the existing utilization technology for treating coal gangue is relatively rough, resulting in low resource utilization rate of coal gangue. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a method for treating lithium-gallium-rich coal gangue, so as to solve the problem of low resource utilization rate of coal gangue in the prior art.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions.

[0007] The present invention provides a method for treating coal gangue rich in lithium gallium, comprising the following steps:

[0008] Step 1: Screening the coal gangue raw material to obtain oversize gangue and undersize gangue;

[0009] Step 2: pre-sorting the gangue on the screen to obtain lithium-gallium-rich sorting concentrate and iron-rich sorting tailings;

[0010] Step 3: crushing the undersized gangue and the selected concentrate to obtain a crushed mixed material;

[0011] Step 4: calcining the crushed mixed material magnetically to obtain a calcined product;

[0012] Step 5: magnetically separating the roasted product to obtain magnetically separated tailings and magnetically separated concentrates rich in iron;

[0013] Step 6: Mix the magnetic separation tailings with the roasting aid, and then perform activation roasting, acid leaching and filtration in sequence to obtain leaching residue and lithium gallium leaching solution;

[0014] Step 7: Separate and purify the lithium-gallium leaching solution to obtain metallic lithium and metallic gallium, thereby completing the treatment of lithium-gallium-rich coal gangue.

[0015] Further, step 3 includes the following steps:

[0016] Step 31: crushing the undersized gangue and the selected concentrate using a crusher to obtain crushed particles;

[0017] Step 32: Use a grinder to grind and dissociate the particles after the primary crushing to obtain a crushed mixed material.

[0018] Furthermore, in step 31, the particle size of the crushed particles is less than 0.5 mm.

[0019] Furthermore, in the crushed mixture, particles with a particle size range of -0.074 mm account for more than 90%.

[0020] Furthermore, in step 4, the magnetic calcination temperature is 450-550° C., the magnetic calcination time is 15-45 min, and the magnetic calcination atmosphere is air or nitrogen.

[0021] Furthermore, in step 5, the magnetic separation intensity is 200-400 mT.

[0022] Furthermore, in step 6, the activation roasting temperature is 600-800° C., and the activation roasting time is 1-2 hours.

[0023] Furthermore, in step 6, the roasting aid includes one or two of NaCl, CaCl2, Na2CO3, CaO, CaF2, and NH4Cl mixed in any proportion, and the mass ratio of the roasting aid to the magnetic separation tailings is 0.5 to 1:1.

[0024] Furthermore, in step 6, nitric acid, hydrochloric acid, sulfuric acid, citric acid or oxalic acid is used as the acid leaching solution, the concentration of the acid leaching solution is 2 to 5 mol / L, the liquid-to-solid ratio of the acid leaching is 1:5 to 10, the acid leaching time is 1 to 3 hours, and the acid leaching temperature is 60 to 80°C.

[0025] Furthermore, the iron-rich sorting tailings obtained in step 2 and the iron-rich magnetic separation concentrate obtained in step 5 are used as raw materials for ironmaking; and / or, the leaching slag obtained in step 6 is used as raw material for preparing water glass.

[0026] Compared with the prior art, the present invention can at least achieve the following beneficial effects:

[0027] A) The method for treating lithium-gallium-rich coal gangue provided by the present invention can achieve efficient utilization of coal gangue and has the characteristics of simple process, wide adaptability, high practicality and low cost.

[0028] B) The method for treating coal gangue rich in lithium and gallium provided by the present invention, on the one hand, pre-sorts the oversize gangue with larger particle size, and pre-discards a part of the sorting tailings rich in iron, which can not only achieve the pre-enrichment of lithium and gallium, but also reduce the processing volume of the subsequent process; on the other hand, through magnetic roasting, pyrite with weaker magnetism is converted into pyrrhotite with stronger magnetism, and the magnetic concentrate rich in iron is further sorted out, thereby reducing the adverse effects of iron in the subsequent leaching process; on the other hand, the magnetic tailings are activated and roasted, which can effectively improve the leaching activity and leaching efficiency of the magnetic tailings; finally, acid leaching is adopted to extract the lithium and gallium elements in the magnetic tailings, which has a simple process, can effectively improve the extraction efficiency, and ensure the efficient and high-value utilization of coal gangue.

[0029] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0031] Figure 1 A flow chart of a method for treating lithium-gallium-rich coal gangue provided by the present invention;

[0032] Figure 2 A schematic diagram of the structure of a processing system in a method for processing lithium-gallium-rich coal gangue provided by the present invention;

[0033] Figure 3 A schematic diagram of the dust removal process in the method for treating lithium-gallium-rich coal gangue provided by the present invention;

[0034] Figure 4 The XRD spectra of the gangue raw material and the gangue before and after magnetic roasting in Examples 1 to 3.

[0035] Reference numerals:

[0036] 1-screening unit; 2-pre-sorting unit; 3-crusher; 4-grinder; 5-magnetic roasting unit; 6-magnetic sorting unit; 7-activated roasting unit; 8-acid leaching unit; 9-mounting rod; 10-reciprocating guide rail; 11-reciprocating sliding filter; 12-mounting sleeve. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] The present invention provides a method for treating coal gangue rich in lithium gallium, see Figure 1 , including the following steps:

[0039] Step 1: using a grading screen (e.g., a 30 mm grading screen) to sieve the coal gangue raw material to obtain oversize gangue and undersize gangue;

[0040] Step 2: According to the difference between the X-ray fluorescence spectra of the oversize gangue, an X-ray fluorescence sorter (i.e., XRF sorter) is used to pre-sort the oversize gangue (large particle material) to obtain a lithium-gallium-rich sorted concentrate and an iron-rich sorted tailings;

[0041] Step 3: crushing the undersized gangue and the selected concentrate to obtain a crushed mixed material;

[0042] Step 4: using a tubular furnace to perform magnetic roasting on the crushed mixed material to obtain a roasted product;

[0043] Step 5: Using the difference in magnetic strength between different minerals, a magnetic separator is used to magnetically separate the roasted product to obtain magnetic tailings and iron-rich magnetic concentrate;

[0044] Step 6: Mix the magnetic separation tailings with the roasting aid, and then perform activation roasting, acid leaching and filtration in sequence to obtain leaching residue and lithium gallium leaching solution;

[0045] Step 7: Separate and purify the lithium-gallium leaching solution to obtain metallic lithium and metallic gallium, thereby completing the treatment of lithium-gallium-rich coal gangue.

[0046] Compared with the prior art, the treatment method for lithium-gallium-rich coal gangue provided by the present invention can achieve efficient utilization of coal gangue, and has the characteristics of simple process, wide adaptability, high practicality, low cost, etc.

[0047] Specifically, on the one hand, the gangue with larger particle size is pre-sorted, and a part of the iron-rich sorting tailings is discarded in advance, which can not only achieve the pre-enrichment of lithium and gallium, but also reduce the processing volume of subsequent processes; on the other hand, through magnetic roasting, the pyrite with weaker magnetism is converted into pyrrhotite with stronger magnetism, and the iron-rich magnetic concentrate is further sorted out, thereby reducing the adverse effects of iron in the subsequent leaching process; on the other hand, the activation roasting of the magnetic tailings can effectively improve the leaching activity and leaching efficiency of the magnetic tailings; finally, acid leaching is used to extract the lithium and gallium elements in the magnetic tailings. The process is simple, which can effectively improve the extraction efficiency and ensure the efficient and high-value utilization of the gangue.

[0048] In order to further utilize the obtained tailings, the iron-rich sorting tailings obtained in step 2 and the iron-rich magnetic separation concentrate obtained in step 5 are used as raw materials for ironmaking.

[0049] In order to further utilize the obtained leaching residue, the leaching residue obtained in the above step 6 mainly contains SiO2, which can be used as a raw material for preparing water glass.

[0050] In order to ensure the adequacy of subsequent roasting and leaching, the above step 3 includes the following steps:

[0051] Step 31: crushing the undersize gangue and the selected concentrate by a crusher (e.g., a roller crusher) to obtain crushed particles, wherein the particle size of the crushed particles is less than 0.5 mm;

[0052] Step 32: Grind and dissociate the particles after the primary crushing using a grinder (eg, a rod mill) to obtain a crushed mixed material.

[0053] The above method is used to crush and grind the undersize gangue and the sorted concentrate, which can ensure the full dissociation of the undersize gangue and the sorted concentrate, promote full reaction during subsequent roasting and leaching, improve roasting efficiency, sorting effect and leaching efficiency, and further improve the resource utilization rate of coal gangue.

[0054] It should be noted that after crushing and grinding, the particle size range of the crushed mixture is -0.074mm, accounting for more than 90%.

[0055] It is worth noting that by controlling the roasting conditions, the residual pyrite with weaker magnetism in the crushed mixture can be converted into pyrrhotite with stronger magnetism. For example, in the above step 4, the magnetic roasting temperature is 450-550°C, the magnetic roasting time is 15-45 minutes, and the magnetic roasting atmosphere is air or nitrogen.

[0056] In order to fully magnetically separate the calcined product, illustratively, in the above step 5, the magnetic separation intensity is 200 to 400 mT.

[0057] Considering that the activation calcination conditions will affect the activation efficiency and activation effect, illustratively, in the above step 6, the activation calcination temperature is 600-800° C., and the activation calcination time is 1-2 h.

[0058] In order to ensure the effect of activation roasting, illustratively, in the above step 6, the roasting aid includes one or two of NaCl, CaCl2, Na2CO3, CaO, CaF2, NH4Cl mixed in any proportion, and the mass ratio of the roasting aid to the magnetic separation tailings is 0.5 to 1:1.

[0059] In order to ensure sufficient leaching of lithium and gallium elements, in the above step 6, for acid leaching, nitric acid, hydrochloric acid, sulfuric acid, citric acid or oxalic acid is used as the acid leaching solution, the concentration of the acid leaching solution is 2-5 mol / L, the liquid-to-solid ratio of the acid leaching is 1:5-10, the acid leaching time is 1-3h, and the acid leaching temperature is 60-80°C.

[0060] For example, the above-mentioned treatment method for lithium-gallium-rich coal gangue adopts a treatment system with the following structure, see Figure 2 , comprising a screening unit 1 (e.g., a grading screen), a pre-sorting unit 2 (e.g., an X-ray fluorescence sorter), a crushing unit (including a crusher 3 and a grinder 4 connected in sequence), a magnetic roasting unit 5 (e.g., a tubular furnace), a magnetic sorting unit 6 (e.g., a magnetic separator), an activation roasting unit 7 (e.g., a tubular furnace), an acid leaching unit 8 (e.g., an acid leaching tank) and a filtering unit, wherein the above-screen discharge port of the screening unit 1 is connected to the feed port of the pre-sorting unit 2, the sorting concentrate discharge port of the pre-sorting unit 2 and the below-screen discharge port of the screening unit 1 are both connected to the feed port of the crushing unit, the discharge port of the crushing unit is connected to the feed port of the magnetic roasting unit 5, the discharge port of the magnetic roasting unit 5 is connected to the feed port of the magnetic sorting unit 6, the magnetic tailings discharge port of the magnetic sorting unit 6 is connected to the feed port of the activation roasting unit 7, the discharge port of the activation roasting unit 7 is connected to the feed port of the acid leaching unit 8, and the leachate discharge port of the acid leaching unit 8 is connected to the filtering unit.

[0061] Taking into account that a large amount of dust-containing exhaust gas will be generated when crushing the mixed material in the magnetic roasting unit 5, in order to be able to treat the exhaust gas, the above-mentioned treatment system also includes an exhaust gas treatment unit. Specifically, the exhaust gas treatment unit includes a heat exchanger, a cooler and a dust collector which are connected to the exhaust gas outlet of the magnetic roasting unit 5 in sequence.

[0062] Exhaust dust removal is a key step in exhaust gas treatment. In order to improve the dust removal effect and efficiency, illustratively, the above-mentioned dust collector includes a dust removal chamber connected to the exhaust gas outlet of the cooler, and a spray water nozzle, a reciprocating sliding filter 11 and an axial flow fan arranged in the dust removal chamber and in sequence along the exhaust gas flow direction. The spray direction of the spray water nozzle is along the exhaust gas direction and toward the reciprocating sliding filter 11, which is used to form a water film on the reciprocating sliding filter 11, and the reciprocating sliding filter 11 reciprocates along the exhaust gas flow direction.

[0063] Regarding the driving method of the reciprocating sliding filter 11, the above-mentioned dust collector also includes a reciprocating driving assembly, a mounting rod 9 and a reciprocating guide rail 10. A mounting sleeve 12 is provided on the reciprocating sliding filter 11. The mounting sleeve 12 has a through hole axially opened, and the cross-sectional shape of the through hole is a long strip. One end of the above-mentioned mounting rod 9 is inserted into the through hole and there is a gap between the mounting rod 9 and the hole wall of the through hole in the vertical direction. The reciprocating guide rail 10 is arranged in the dust removal chamber and can rotate in the horizontal direction. The cross-sectional shape of the reciprocating guide rail 10 parallel to the movement direction of the reciprocating sliding filter 11 is a triangle.

[0064] During implementation, the initial position of the reciprocating sliding filter screen 11 is the lowest point of the reciprocating guide rail 10 (i.e., the end away from the spray water nozzle, the height of the lowest point is 0). During the reciprocating motion of the reciprocating sliding filter screen 11, the reciprocating sliding filter screen 11 gradually moves upward along the reciprocating guide rail 10. At the same time, the end of the mounting sleeve 12 moves upward in the through hole, and the displacement of the reciprocating sliding filter screen 11 in the vertical direction is adapted through the gap between the through hole and the mounting sleeve 12. When the reciprocating sliding filter screen 11 reaches the highest point of the reciprocating guide rail 10 and continues to move, it will suddenly detach from the reciprocating guide rail 10, fall in the vertical direction and generate vibration. The vibration causes the liquid film to immediately detach from the reciprocating sliding filter screen 11, and the droplets sprayed from the spray water nozzle will form a new liquid film on the reciprocating sliding filter screen 11. At the same time, the reciprocating guide rail 10 rotates 180° and repeats the above movement process. See Figure 3 .

[0065] The processing method of the present invention is described in detail below in conjunction with Examples 1 to 3:

[0066] Examples 1 to 3 are directed to the treatment of coal gangue in Shuozhou, Shanxi Province, and the specific treatment steps are as follows:

[0067] The coal gangue raw material rich in lithium and gallium is fed into a 30mm grading screen, and the original sample is separated into oversize gangue and undersize gangue by the grading screen; the oversize gangue is fed into an XRF sorter, and the XRF spectrum of the oversize gangue is obtained by X-ray, and the difference between the XRF spectra of different oversize gangues is used to sort them into lithium-gallium-rich sorting concentrate and iron-rich sorting tailings; the undersize gangue and the sorting concentrate of the XRF sorter are fed into a roller crusher for crushing, and the particle size of the crushed particles is less than 0.5mm, and the sorting tailings can be used as iron-rich gangue as raw material for ironmaking; the crushed particles are fed into a rod mill for further grinding and dissociation to ensure that the crushed particles can fully react during subsequent activation roasting and acid leaching; the crushed mixture (particle size range 200-300mm) after grinding and dissociation is crushed into a granular material (particle size range 200-300mm) and then ... The ore having a circumference of -0.074 mm accounts for more than 90%) is placed in a tubular furnace for magnetization roasting to convert the residual pyrite with weaker magnetism in the crushed mixture into pyrrhotite with stronger magnetism; the roasted product is fed into a magnetic separator for magnetic separation, and the difference in magnetic strength between different roasted products is used to separate them into magnetic tailings and iron-rich magnetic concentrate, and the iron-rich magnetic concentrate is used as the raw material for ironmaking; the magnetic tailings are mixed with a roasting aid and placed together in a tubular furnace for activation roasting; the magnetic tailings after activation roasting are leached with an acid solution, and finally separated by filtration to obtain a lithium gallium leaching solution and a leaching residue; the lithium gallium leaching solution is further separated and purified to obtain lithium and gallium that meet the product requirements, and the leaching residue is used as the raw material for preparing water glass.

[0068] The process parameters in the above steps are shown in Table 1.

[0069] Table 1 Process parameters of Examples 1 to 3

[0070]

[0071] The data on the utilization effect of the above treatment methods on coal gangue are shown in Table 2.

[0072] Table 2 Utilization effect data of coal gangue of Examples 1 to 3

[0073] Magnetic concentrate % Concentrate grade% Lithium leaching rate % Gallium leaching rate % Example 1 8.34 47.96 97.11 94.67 Example 2 11.19 40.06 90.97 86.61 Example 3 10.87 40.19 93.56 90.43

[0074] As can be seen from Table 2, after the lithium-gallium-rich coal gangue is processed and utilized by the method of the present invention, about 10% of the iron-rich raw materials (8.34-11.19%) can be effectively separated, and the grade thereof reaches more than 40% (40.06-47.96%), and can be used as iron-making raw materials after further processing. After the iron-rich gangue in the original sample is removed by magnetic separation, the iron content in the subsequent leaching solution is greatly reduced, which is extremely beneficial for the subsequent separation and purification of gallium. The magnetic tailings are leached after activation, and the leaching efficiency is relatively high. The leaching rate of lithium is more than 90% (90.97-97.11%), and the leaching rate of gallium is also more than 86% (86.61-94.67%), and the lithium-gallium elements in the coal gangue are effectively recovered and utilized.

[0075] right Figure 4 It can be seen that after the gangue is subjected to magnetization roasting treatment, the pyrite with weaker magnetism in the original sample is transformed into pyrrhotite with stronger magnetism, and the iron-rich gangue can be effectively separated from the rest by magnetic separation. However, due to the short magnetization roasting time, the kaolinite structure in the gangue cannot be completely destroyed, and the lithium and gallium elements in the gangue cannot be effectively leached. Therefore, secondary activation roasting is required in the follow-up to completely destroy the kaolinite structure in the gangue and effectively realize the recycling of lithium and gallium elements in the gangue.

[0076] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for treating coal gangue rich in lithium and gallium, characterized in that: The steps include: Step 1: Screening the coal gangue raw material to obtain oversize gangue and undersize gangue; Step 2: pre-sorting the gangue on the screen to obtain lithium-gallium-rich sorting concentrate and iron-rich sorting tailings; Step 3: crushing the undersized gangue and the selected concentrate to obtain a crushed mixed material; Step 4: calcining the crushed mixed material magnetically to obtain a calcined product; Step 5: magnetically separating the roasted product to obtain magnetically separated tailings and magnetically separated concentrates rich in iron; Step 6: Mix the magnetic separation tailings with the roasting aid, and then perform activation roasting, acid leaching and filtration in sequence to obtain leaching residue and lithium gallium leaching solution; Step 7: Separate and purify the lithium-gallium leaching solution to obtain metallic lithium and metallic gallium, thereby completing the treatment of lithium-gallium-rich coal gangue.

2. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: The step 3 comprises the following steps: Step 31: crushing the undersized gangue and the selected concentrate using a crusher to obtain crushed particles; Step 32: Use a grinder to grind and dissociate the particles after the primary crushing to obtain a crushed mixed material.

3. The method for treating lithium-gallium-rich coal gangue according to claim 2, characterized in that: In the step 31, the particle size of the crushed particles is less than 0.5 mm.

4. The method for treating lithium-gallium-rich coal gangue according to claim 2, characterized in that: In the crushed mixture, particles with a particle size range of -0.074 mm account for more than 90%.

5. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: In the step 4, the magnetic roasting temperature is 450-550° C., the magnetic roasting time is 15-45 minutes, and the magnetic roasting atmosphere is air or nitrogen.

6. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: In the step 5, the magnetic separation intensity is 200-400 mT.

7. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: In the step 6, the activation roasting temperature is 600-800° C., and the activation roasting time is 1-2 hours.

8. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: In step 6, the roasting aid includes one or two of NaCl, CaCl2, Na2CO3, CaO, CaF2, and NH4Cl mixed in any proportion, and the mass ratio of the roasting aid to the magnetic separation tailings is 0.5 to 1:

1.

9. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: In step 6, nitric acid, hydrochloric acid, sulfuric acid, citric acid or oxalic acid is used as the acid leaching solution, the concentration of the acid leaching solution is 2-5 mol / L, the liquid-to-solid ratio of the acid leaching is 1:5-10, the acid leaching time is 1-3 hours, and the acid leaching temperature is 60-80°C.

10. The method for treating lithium-gallium-rich coal gangue according to claim 1, characterized in that: The iron-rich separation tailings obtained in step 2 and the iron-rich magnetic separation concentrate obtained in step 5 are used as raw materials for ironmaking; And / or, the leached residue obtained in step 6 is used as raw material for preparing water glass.

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