Low-grade lithium ore comprehensive utilization method based on sintering method

Abstract

The invention relates to a low-grade lithium ore comprehensive utilization method based on a sintering method, which comprises the following steps: proportioning low-grade lithium ore and limestone, and then calcining and leaching to obtain leaching slag and leaching liquid; the leaching residues are washed, washing liquid obtained through washing and leaching liquid are mixed, and total leaching liquid is obtained; sequentially carrying out first concentration, solid-liquid separation, carbonization and pyrolysis on the total leachate to obtain lithium carbonate and pyrolysis mother liquor; sequentially carrying out second concentration and crystallization on the pyrolysis mother solution to obtain a sodium carbonate product and a crystallized solution; sequentially carrying out carbonation, roasting and solid-liquid separation on the crystallized liquid to obtain a potassium carbonate product and a separation liquid; and the separated liquid is subjected to third concentration and drying, and a rubidium-cesium mixed alkali crude product is obtained. The method provided by the invention adopts a limestone roasting process, has the advantages of simple flow, easily available raw materials, low cost and light corrosion to equipment, and has the advantages of high product purity, energy conservation, emission reduction and low production cost compared with a traditional process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction from ores, and particularly relates to a comprehensive utilization method of low-grade lithium ores based on a sintering method. Background Art

[0002] Currently, the main lithium extraction technologies are lithium extraction from pegmatite ores and salt lake brines. Comparing the two processes of lithium extraction from lithium ores and brines: Lithium extraction from brines has problems such as difficult magnesium-lithium separation, poor process versatility, and difficult purification. In recent years, the output is usually lower than that of lithium extraction from ores.

[0003] Common methods for lithium extraction from lithium ores include the sulfuric acid method, limestone method, sulfate method, soda pressure cooking method, chlorination roasting method, etc.

[0004] For example, CN112575339A discloses a method for preparing lithium hydroxide by the sulfuric acid method from spodumene and a method for removing sodium and potassium. The method includes: 1) roasting; 2) acidification, leaching, and filtration to obtain a lithium sulfate mother liquor; 3) removing high-valent metal ions in the lithium sulfate mother liquor; 4) electro-dialysis to remove sodium and potassium; 5) bipolar membrane electrolysis to obtain a lithium hydroxide solution and dilute sulfuric acid; 6) concentrating and crystallizing the lithium hydroxide solution to obtain a lithium hydroxide product, that is, battery-grade lithium hydroxide can be prepared, and the process does not require freezing and adding alkali, and the method is simple, environmentally friendly, and low in cost.

[0005] CN1109104A discloses a process for producing lithium hydroxide by roasting lepidolite with limestone. Using lepidolite and limestone as raw materials, first roast lepidolite at high temperature in the presence of steam to obtain roasted lepidolite, then subject the ground roasted lepidolite to pressure cooking leaching together with slaked lime, returned part of the mother liquor, and residue washing water. After impurity removal from the leaching solution, lithium hydroxide product is precipitated by evaporation and crystallization. This method can reduce the amount of slag, reduce the amount of limestone used, and the recovery rate reaches 80%, greatly improving its production capacity.

[0006] CN109133118A discloses a process for preparing lithium carbonate by the soda pressure cooking method from spodumene. Using the sodium carbonate soda pressure cooking method to extract lithium from spodumene to prepare battery-grade lithium carbonate. After the spodumene undergoes a sodium carbonate pressure cooking reaction, the obtained lithium carbonate and slag are placed in a high-pressure autoclave for deep carbonization to completely convert the lithium carbonate into soluble lithium bicarbonate. After filtration, the lithium bicarbonate filtrate is separated, and then the lithium bicarbonate solution is heated and decomposed to obtain high-purity lithium carbonate, and a lithium carbonate product with a purity of 99.6% can be obtained.

[0007] CN114507779A discloses a method for producing lithium sulfate by sulfate roasting. The method includes the following steps: mixing a spodumene ore with a roasting aid in a certain proportion and uniformly roasting in a muffle furnace to obtain a roasted material; after the roasted material is cooled, leach the roasted material with water to obtain a lithium sulfate solution. This invention uses water leaching instead of acid leaching, greatly reducing problems such as equipment corrosion and improving economic benefits.

[0008] CN115947355A discloses a process for preparing battery-grade lithium carbonate by chlorination roasting of lepidolite, which includes the following steps: grinding and pre-roasting lepidolite, introducing chlorine for reaction, adding sodium hydroxide to prepare a precipitate, making the precipitate into a gel, adding a reactant to produce a by-product, and concentrating and enriching Li + and treating the lithium carbonate precipitate. This method has a high lithium recovery rate, and at the same time, the by-product has great application value and saves resources.

[0009] Among them, compared with other processes, the limestone roasting process has the advantages of simple process, light equipment corrosion, simple impurity removal process, and easy industrial production. However, it also has problems such as low lithium recovery rate, large amount of slag, and large amount of waste gas emissions. Usually, methods such as fine grinding, pressurization, improving washing and evaporation processes can be used to reduce the amount of slag and increase the recovery rate, but there are not many processes to reduce the emissions of waste gases such as CO2. The traditional lithium precipitation process obtains products by adding carbonates. The lithium precipitation process is relatively complex, and the large amount of carbonates added will also introduce new impurities, resulting in high costs and low economic benefits.

[0010] Therefore, aiming at the technical deficiencies such as low lithium recovery rate and high carbon dioxide emissions, there is an urgent need for a clean production method for comprehensive recovery of multi-metals from low-grade mixed lithium ores to achieve the efficient recovery of low-grade lithium ores. Summary of the Invention

[0011] In view of the problems existing in the prior art, the purpose of the present invention is to provide a comprehensive utilization method for low-grade lithium ores based on the sintering method to solve the current problems of low lithium recovery rate and high carbon dioxide emissions.

[0012] To achieve this purpose, the present invention adopts the following technical solutions:

[0013] The present invention provides a comprehensive utilization method for low-grade lithium ores based on the sintering method, and the comprehensive utilization method includes:

[0014] Mixing low-grade lithium ores with limestone, and then carrying out calcination and leaching to obtain leaching residues and leaching solutions;

[0015] Washing the leaching residues, and mixing the obtained washing solution and the leaching solution to obtain a total leaching solution;

[0016] Carrying out first concentration, solid-liquid separation, carbonization and pyrolysis on the total leaching solution in sequence to obtain lithium carbonate and pyrolysis mother liquor;

[0017] Carrying out second concentration and crystallization on the pyrolysis mother liquor in sequence to obtain sodium carbonate products and post-crystallization liquid;

[0018] Carrying out carbonization, roasting and solid-liquid separation on the post-crystallization liquid in sequence to obtain potassium carbonate products and separation liquid;

[0019] The separation liquid is subjected to third concentration and drying to obtain a crude product of rubidium-caesium mixed alkali.

[0020] The comprehensive utilization method provided by the present invention uses a limestone roasting process, which has a simple process, easily available raw materials, low cost, and light corrosion to equipment; during the carbonization and carbonation processes, the CO2 generated during the roasting process can be fully utilized to precipitate carbonates. This process not only solves the problem of large exhaust gas emissions in the roasting process, but also does not require additional addition of other chemical reagents. Compared with the traditional process, this process has high product purity, energy conservation and emission reduction, low production cost, greatly increases economic benefits, and is easy for industrial production.

[0021] As a preferred technical solution of the present invention, the particle size of the low-grade lithium ore is ≥50 mesh.

[0022] Preferably, the mass ratio of the low-grade lithium ore to limestone is 1:(1-6).

[0023] As a preferred technical solution of the present invention, the sintering temperature is 850-1300 °C.

[0024] Preferably, the sintering time is 0.5-6 h.

[0025] Preferably, the sintering method includes rotary kiln sintering.

[0026] As a preferred technical solution of the present invention, the liquid-solid ratio mL / g of the leaching is (1-7):1.

[0027] Preferably, the leaching method includes water leaching.

[0028] Preferably, the leaching temperature is 50-150 °C.

[0029] Preferably, the leaching time is 0.5-5 h.

[0030] As a preferred technical solution of the present invention, the liquid-solid ratio mL / g of the washing is (1-7):1.

[0031] Preferably, the washing temperature is 50-150 °C.

[0032] Preferably, the washing time is 0.5-5 h.

[0033] Preferably, the washing is carried out 1-4 times.

[0034] As a preferred technical solution of the present invention, the temperature of the first concentration is 90-180 °C.

[0035] Preferably, the time of the first concentration is 0.5-5 h.

[0036] As a preferred technical solution of the present invention, the carbonization is carried out by introducing carbon dioxide gas into the liquid phase.

[0037] Preferably, the flow rate of carbon dioxide gas in the carbonization is 0.1 - 5 L / min.

[0038] Preferably, the time of carbonization is 0.5 - 5 h.

[0039] As a preferred technical solution of the present invention, the temperature of pyrolysis is 50 - 150 °C.

[0040] Preferably, the time of pyrolysis is 0.5 - 5 h.

[0041] Preferably, the temperature of the second concentration is 90 - 180 °C.

[0042] Preferably, the time of the second concentration is 0.5 - 5 h.

[0043] As a preferred technical solution of the present invention, the carbonization is carried out by introducing carbon dioxide gas into the liquid for treatment.

[0044] Preferably, the temperature of carbonization is 10 - 50 °C.

[0045] Preferably, the flow rate of carbon dioxide in the carbonization is 0.1 - 5 L / min.

[0046] Preferably, the time of carbonization is 0.5 - 5 h.

[0047] As a preferred technical solution of the present invention, the temperature of the third concentration is 90 - 180 °C.

[0048] Preferably, the time of the third concentration is 0.5 - 5 h.

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

[0050] The present invention adopts a clean production method for comprehensive recovery of multi-metals from low-grade mixed lithium ores, using a limestone roasting process, which has a simple process, easily available raw materials, low cost, and light corrosion to equipment; it can make full use of the CO2 generated during the roasting process to precipitate carbonates. This process not only solves the problem of large exhaust gas emissions in the roasting process, but also does not require additional addition of other chemical reagents. Compared with the traditional process, this process has high product purity, energy conservation and emission reduction, and low production cost, greatly increasing economic benefits, and is easy to industrialize. The purity of the obtained lithium carbonate product is ≥99.58%, the purity of the sodium carbonate product is ≥98.72%, and the purity of the potassium carbonate product is ≥98.15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1It is the flow chart of the comprehensive utilization method of low-grade lithium ore based on the sintering method provided by the present invention.

[0052] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the claimed rights of the present invention. The scope of protection of the present invention shall be subject to the claims. Detailed implementation manners

[0053] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0054] This embodiment provides a comprehensive utilization method of low-grade lithium ore based on the sintering method. The flow chart is as Figure 1 shown and includes:

[0055] Mix the low-grade lithium ore with limestone, then carry out calcination and leaching to obtain leaching residues and leaching solutions;

[0056] Wash the leaching residues, and mix the obtained washing solutions with the leaching solutions to obtain total leaching solutions;

[0057] Carry out first concentration, solid-liquid separation, carbonization and pyrolysis on the total leaching solutions in sequence to obtain lithium carbonate and pyrolysis mother liquor;

[0058] Carry out second concentration and crystallization on the pyrolysis mother liquor in sequence to obtain sodium carbonate products and post-crystallization solutions;

[0059] Carry out carbonation, roasting and solid-liquid separation on the post-crystallization solutions in sequence to obtain potassium carbonate products and separation solutions;

[0060] Carry out third concentration and drying on the separation solutions to obtain crude rubidium-caesium mixed alkali products.

[0061] Specifically, the particle size of the low-grade lithium ore is ≥50 mesh, that is, the products passing through a 50-mesh sieve can all implement the solution of the present invention. As those skilled in the art know, as the mesh number increases, the sieve-passing particle size of the particles gradually decreases. For example, the products passing through a 100-mesh sieve hole, the products passing through a 200-mesh sieve hole, and also the materials between the products passing through a 50-mesh sieve and those not passing through a 200-mesh sieve, and the materials between the products passing through a 100-mesh sieve and those not passing through a 200-mesh sieve. Other ranges will not be elaborated here, and so on.

[0062] In the present invention, the low-grade lithium ore is composed of 1 or at least 2 kinds of mixed ores selected from spodumene, petalite, lepidolite, amblygonite, lithium porcelain stone and other lithium ores. Low grade means that the grade of lithium in a single lithium ore or the mixed lithium ore is ≤2.8 wt% calculated as Li2O.

[0063] In the present invention, the concentration method includes evaporation, distillation and other methods.

[0064] Specifically, the mass ratio of the low-grade lithium ore to limestone is 1:(1 - 6). For example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, or 1:6, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0065] Specifically, the sintering temperature is 850 - 1300 °C. For example, it can be 850 °C, 900 °C, 950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1200 °C, 1250 °C, or 1300 °C, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0066] Specifically, the sintering time is 0.5 - 6 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, or 6 h, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0067] Specifically, the sintering method includes rotary kiln sintering.

[0068] Specifically, the liquid-solid ratio mL / g for leaching is (1 - 7):1. For example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, or 1:7, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0069] Specifically, the leaching method includes water leaching.

[0070] Specifically, the leaching temperature is 50 - 150 °C. For example, it can be 50 °C, 60 °C, 80 °C, 100 °C, 120 °C, 140 °C, or 150 °C, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0071] Specifically, the leaching time is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0072] Specifically, the liquid-solid ratio mL / g for washing is (1 - 7):1. For example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, or 1:7, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0073] Specifically, the temperature of the washing is 50 - 150 °C. For example, it can be 50 °C, 60 °C, 80 °C, 100 °C, 120 °C, 140 °C, 150 °C, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0074] Specifically, the time of the washing is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0075] Specifically, the washing is carried out 1 - 4 times. For example, it can be 1 time, 2 times, 3 times, 4 times, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0076] Specifically, the temperature of the first concentration is 90 - 180 °C. For example, it can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0077] Specifically, the time of the first concentration is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0078] Specifically, the carbonization is carried out by introducing carbon dioxide gas into the liquid phase.

[0079] Specifically, the carbon dioxide gas comes from the sintering process. Carbon dioxide gas from other sources can also be used, such as commercially available carbon dioxide gas or carbon dioxide generated in other industrial production processes.

[0080] Specifically, the flow rate of the carbon dioxide gas in the carbonization is 0.1 - 5 L / min. For example, it can be 0.1 L / min, 0.2 L / min, 0.4 L / min, 0.6 L / min, 0.8 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4 L / min, 4.5 L / min, 5 L / min, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0081] Specifically, the carbonization time is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0082] Specifically, the pyrolysis temperature is 50 - 150 °C. For example, it can be 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, or 150 °C, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0083] Specifically, the pyrolysis time is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0084] In the present invention, the surface of the lithium carbonate product obtained by pyrolysis contains certain soluble salts. Optionally, washing can be carried out to remove the soluble salts. The washing temperature is 50 - 150 °C, and the washing time is 0.5 - 3 h.

[0085] Specifically, the temperature of the second concentration is 90 - 180 °C. For example, it can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, or 180 °C, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0086] Specifically, the time of the second concentration is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0087] In the present invention, soluble salts adhere to the surface of the crystallized sodium carbonate. Saturated sodium carbonate can be selected for multiple washings. The washing temperature is 0 - 50 °C, and the washing time is 0.5 - 3 h, thereby further improving the purity of sodium carbonate.

[0088] Specifically, the carbonation is carried out by introducing carbon dioxide gas into the liquid phase for treatment.

[0089] Specifically, the carbonation temperature is 10 - 50 °C. For example, it can be 10 °C, 20 °C, 30 °C, 40 °C, or 50 °C, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0090] Specifically, the flow rate of carbon dioxide in the carbonation is 0.1 - 5 L / min. For example, it can be 0.1 L / min, 0.2 L / min, 0.4 L / min, 0.6 L / min, 0.8 L / min, 1 L / min, 1.5 L / min, 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4 L / min, 4.5 L / min, or 5 L / min, etc. However, it is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0091] Specifically, the time of the carbonation is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc. However, it is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0092] In the present invention, soluble salts adhere to the surface of the potassium bicarbonate precipitated by carbonation. It is necessary to wash it with deionized water for multiple times and then calcine it to obtain the potassium carbonate product. The washing temperature is 0 - 50 °C, and the washing time is 0.5 - 5 h.

[0093] In the present invention, the calcination parameters of the potassium bicarbonate obtained by carbonation can be designed according to the parameters of the decomposition of potassium bicarbonate into potassium carbonate and carbon dioxide.

[0094] In the present invention, soluble salts adhere to the surface of the potassium bicarbonate precipitated by carbonation. During the process of washing it with deionized water for multiple times and then calcining it to obtain the potassium carbonate product, the washing temperature is 0 - 50 °C. For example, it can be 0 °C, 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, or 50 °C, etc. However, it is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0095] In the present invention, soluble salts adhere to the surface of the potassium bicarbonate precipitated by carbonation. During the process of washing it with deionized water for multiple times and then calcining it to obtain the potassium carbonate product, the washing time is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc. However, it is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0096] Specifically, the temperature of the third concentration is 90 - 180 °C. For example, it can be 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, or 180 °C, etc. However, it is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0097] Specifically, the time for the third concentration is 0.5 - 5 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., but is not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0098] Furthermore, in order to illustrate the high - efficiency recovery effect of the comprehensive utilization method provided by the present invention, actual examples are used for illustration as follows:

[0099] Example 1

[0100] This example provides a comprehensive utilization method for low - grade lithium ore based on the sintering method, which is as follows:

[0101] In this example, the selected lithium ore material is a mixture of spodumene and lepidolite ores. The main components, by mass percentage, are: Li2O 2.5 wt%, K2O 4.8 wt%, Na2O 1.75 wt%, Rb2O 0.7 wt%, SiO2 74.4 wt.%, and Al2O3 17.18 wt%.

[0102] Specifically, the lithium ore material passing through a 200 - mesh sieve is selected and mixed evenly with limestone in a ratio of 1:2 to obtain raw materials. The raw materials are put into a rotary kiln and calcined at 1000 °C for 3 h to obtain clinker. The clinker is ground fine by a ball mill and then added to a leaching tank with water in a ratio of 1:4. The leaching temperature is 110 °C, the leaching time is 2 h, and stirring is carried out to leach out soluble salts. Then, filtration is carried out to collect the lithium - containing leaching solution.

[0103] The filter residue is washed twice with deionized water in a ratio of 1:4. The washing temperature is 100 °C and the time is 0.5 h. The leaching solution and all washing solutions are evaporated and concentrated. After filtering out the precipitated impurities, CO2 generated in the sintering process is introduced to make it fully carbonized. The temperature is 20 °C, the ventilation rate is 0.6 L / min, and the time is 0.5 h. The impurities are filtered, and the two - time impurities are washed. The filtered carbonized solution is pyrolyzed at 100 °C for 1 h, and the precipitated lithium carbonate is washed twice to obtain lithium carbonate.

[0104] The pyrolysis mother liquor after 3 - time enrichment is evaporated and concentrated at 100 °C for 2 h to crystallize out crude sodium carbonate, which is washed with saturated sodium carbonate solution at 25 °C for 1 h and washed 3 times to obtain sodium carbonate products.

[0105] The solution from which sodium carbonate is precipitated is introduced with CO2 generated in the sintering process to make it fully carbonized. The temperature is 25 °C, the ventilation rate is 0.6 L / min, and the time is 0.5 h. Crude potassium bicarbonate is filtered out, washed with deionized water at 25 °C for 1 h, and calcined after washing 3 times to obtain potassium carbonate products.

[0106] The rich rubidium and cesium mother liquor after potassium extraction by carbonization is evaporated and concentrated at 100 °C for 2 h, and after drying treatment, a crude rubidium and cesium mixed alkali product is obtained.

[0107] Example 2

[0108] This example provides a comprehensive utilization method of low-grade lithium ore based on the sintering method, which is as follows:

[0109] In this example, the selected lithium ore material is a mixture of three ores: petalite, lepidolite and amblygonite. The main components are as follows in mass percentage: Li2O 2.3 wt%, K2O 5.2 wt%, Na2O 1.8 wt%, Rb2O 1.3 wt%, SiO2 75.4 wt.%, Al2O3 15.2 wt%.

[0110] Specifically, the undersize lithium ore material of 150 mesh is selected and mixed evenly with limestone in a ratio of 1:4 to obtain raw meal. The raw meal is put into a rotary kiln and calcined at 1200 °C for 1 h to obtain clinker. The clinker is ground fine by a ball mill and added to a leaching tank with water in a ratio of 1:2. The leaching temperature is 90 °C, the leaching time is 0.5 h, and stirring is carried out to leach out the soluble salts. Then filtration is carried out to collect the lithium-containing leaching solution.

[0111] The filter residue is washed 3 times with deionized water in a ratio of 1:2. The washing temperature is 130 °C and the time is 2 h. The leaching solution and all washing solutions are evaporated and concentrated. After filtering out the precipitated impurities, CO2 generated in the sintering process is introduced to make it fully carbonized. The temperature is 25 °C, the ventilation volume is 1 L / min, and the time is 3 h. The impurities are filtered, and the two impurities are washed. The filtered carbonized solution is pyrolyzed at 80 °C for 1 h, and the precipitated lithium carbonate is washed 3 times to obtain lithium carbonate.

[0112] The pyrolysis mother liquor after 5 times of enrichment is evaporated and concentrated at 110 °C for 3 h, and crude sodium carbonate is crystallized out. It is washed with saturated sodium carbonate at 20 °C for 2 h and washed 2 times to obtain sodium carbonate product.

[0113] CO2 generated in the sintering process is introduced into the solution from which sodium carbonate is precipitated to make it fully carbonized. The temperature is 20 °C, the ventilation volume is 1.0 L / min, and the time is 0.5 h. Crude potassium bicarbonate is obtained by filtration, washed with deionized water at 20 °C for 2 h and washed 2 times, and then calcined to obtain potassium carbonate product.

[0114] The rich rubidium and cesium mother liquor after potassium extraction by carbonization is evaporated and concentrated at 110 °C for 1 h, and after drying treatment, a crude rubidium and cesium mixed alkali product is obtained.

[0115] Example 3

[0116] This example provides a comprehensive utilization method of low-grade lithium ore based on the sintering method, which is as follows:

[0117] In this embodiment, the lithium ore material selected is a mixture of four ores, spodumene, petalite, lepidolite and lithium porcelain stone. The main components are as follows in terms of mass percentage: Li2O 2.2wt%, K2O 5.12wt%, Na2O 2.55wt%, Rb2O 0.9wt%, SiO2 72.4wt%, Al2O3 20.10wt%.

[0118] Specifically, the lithium ore material passing through a 250-mesh sieve is selected and mixed evenly with limestone in a ratio of 1:2.5 to obtain the raw material. The raw material is put into a rotary kiln and calcined at 1100 °C for 4 h to obtain the clinker. The clinker is ground fine by a ball mill and then added to a leaching tank with water in a ratio of 1:3. The leaching temperature is 120 °C and the leaching time is 1 h. Stir to leach out the soluble salts, filter, and collect the lithium-containing leaching solution. The filter residue is washed once with deionized water in a ratio of 1:3. The washing temperature is 105 °C and the time is 1 h. The leaching solution and all washing solutions are evaporated and concentrated. After filtering out the precipitated impurities, CO2 generated in the sintering process is introduced to make it fully carbonized. The temperature is 30 °C, the ventilation volume is 0.2 L / min, and the time is 1.5 h. Filter out the impurities, and wash the two impurities. The filtered carbonized solution is pyrolyzed at 120 °C for 2 h. The precipitated lithium carbonate is washed 3 times to obtain lithium carbonate.

[0119] The pyrolysis mother liquor after 4 times of enrichment is evaporated and concentrated at 120 °C for 1 h, and crude sodium carbonate is crystallized out. It is washed with saturated sodium carbonate at 15 °C for 0.5 h and washed 3 times to obtain sodium carbonate product.

[0120] CO2 generated in the sintering process is introduced into the solution from which sodium carbonate is precipitated to make it fully carbonized. The temperature is 15 °C, the ventilation volume is 1.5 L / min, and the time is 0.5 h. Filter to obtain crude potassium bicarbonate, which is washed with deionized water at 15 °C for 0.5 h and calcined after washing 3 times to obtain potassium carbonate product.

[0121] The mother liquor rich in rubidium and cesium after potassium extraction by carbonization is evaporated and concentrated at 120 °C for 3 h, and after drying treatment, a crude product of rubidium-cesium mixed alkali is obtained.

[0122] The purity indexes of the products obtained in Examples 1-3 are shown in Table 1 for details.

[0123] Table 1

[0124] Purity of lithium carbonate Purity of sodium carbonate product Purity of potassium carbonate product Example 1 99.56％ 98.72％ 98.62％ Example 2 99.72％ 99.08％ 98.58％ Example 3 99.80％ 98.95％ 98.15％

[0125] In summary, the clean production method for comprehensive recovery of multiple metals from low-grade mixed lithium ores provided by the present invention can obtain carbonate products with relatively high purity, improving the comprehensive recovery and utilization of low-grade mixed lithium ores. The limestone sintering process adopted by the present invention has the advantages of simple process, easy availability of raw materials, and low corrosion degree of equipment; during this process, the CO2 generated in the roasting process can be fully utilized, without the need to add additional chemical reagents, achieving energy conservation, emission reduction, low cost, improved economic benefits, and being easy for industrial production.

[0126] It is declared that the present invention uses the above embodiments to illustrate the detailed structural features of the present invention, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the components selected by the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0127] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0128] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0129] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A comprehensive utilization method for low-grade lithium ore based on the sintering process, characterized in that The comprehensive utilization method of low-grade lithium ore based on the sintering method includes: Mixing the low-grade lithium ore with limestone, followed by calcination and leaching to obtain leaching residues and leaching solutions; Washing the leaching residues, and mixing the obtained washing solution with the leaching solution to obtain a total leaching solution; Successively performing first concentration, solid-liquid separation, carbonization, and pyrolysis on the total leaching solution to obtain lithium carbonate and pyrolysis mother liquor; Successively performing second concentration and crystallization on the pyrolysis mother liquor to obtain sodium carbonate products and post-crystallization liquid; Successively performing carbonation, roasting, and solid-liquid separation on the post-crystallization liquid to obtain potassium carbonate products and separation liquid; Performing third concentration and drying on the separation liquid to obtain crude rubidium-caesium mixed alkali products.

2. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to claim 1, characterized in that The particle size of the low-grade lithium ore is ≥50 mesh; Preferably, the mass ratio of the low-grade lithium ore to limestone is 1:(1-6).

3. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to claim 1 or 2, characterized in that, The temperature of the sintering is 850-1300°C; Preferably, the time of the sintering is 0.5-6h; Preferably, the sintering method includes rotary kiln sintering.

4. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to any one of claims 1-3, characterized in that, The liquid-solid ratio mL / g of the leaching is (1-7):1; Preferably, the leaching method includes water leaching; Preferably, the temperature of the leaching is 50-150°C; Preferably, the time of the leaching is 0.5-5h.

5. The comprehensive utilization method of low-grade lithium ore based on the sintering method according to any one of claims 1-4, characterized in that The liquid-solid ratio mL / g of the washing is (1-7):1; Preferably, the temperature of the washing is 50-150°C; Preferably, the time of the washing is 0.5-5h; Preferably, the washing is performed 1-4 times.

6. The comprehensive utilization method of low-grade lithium ore based on the sintering method according to any one of claims 1-5, characterized in that, The temperature of the first concentration is 90-180°C; Preferably, the time of the first concentration is 0.5-5h.

7. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to any one of claims 1-6, characterized in that The carbonization is carried out by introducing carbon dioxide gas into the liquid phase; Preferably, the flow rate of carbon dioxide gas in the carbonization is 0.1-5L / min; Preferably, the time of the carbonization is 0.5-5h.

8. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to any one of claims 1-7, characterized in that, The temperature of the pyrolysis is 50-150°C; Preferably, the time of the pyrolysis is 0.5-5h; Preferably, the temperature of the second concentration is 90-180°C; Preferably, the time of the second concentration is 0.5-5h.

9. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to any one of claims 1-8, characterized in that, The carbonization is carried out by introducing carbon dioxide gas into the liquid for treatment; Preferably, the temperature of the carbonization is 10-50°C; Preferably, the flow rate of carbon dioxide in the carbonization is 0.1-5L / min; Preferably, the time of the carbonization is 0.5-5h.

10. The comprehensive utilization method of low-grade lithium ore based on the sintering process according to any one of claims 1-9, characterized in that, The temperature of the third concentration is 90-180°C; Preferably, the time of the third concentration is 0.5-5h.

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