Method for extracting lithium from spodumene and by-producing low-sulfur lithium smelting slag

Abstract

The invention belongs to the technical field of inorganic chemical industry, and particularly discloses a method for extracting lithium from spodumene and by-producing low-sulfur lithium smelting slag. The method comprises the following steps: sequentially carrying out roasting transformation and sulfuric acid acidification roasting on spodumene to obtain acidified roasted spodumene; mixing the acidified and roasted spodumene with water, leaching, and carrying out solid-liquid separation to obtain a sulfur-containing lithium-rich solution and a solid phase; washing the solid phase to obtain low-sulfur lithium smelting slag; and reacting the sulfur-containing lithium-rich solution with calcium carbonate to obtain a calcium sulfate byproduct and a lithium-rich solution. Compared with a traditional spodumene two-stage lithium extraction process, the method has the advantages that the acidolysis slurry is directly subjected to acid filtration, the problem of associated generation of spodumene smelting slag and calcium sulfate is avoided, the problem that the spodumene smelting slag is difficult to utilize is thoroughly solved from the source, meanwhile, the lithium-rich solution and the calcium sulfate by-product are produced, and the method is suitable for industrial production. And the discharge amount of the spodumene smelting slag and the environmental poison risk are greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic chemical industry, and in particular to a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product. Background Art

[0002] With the rapid development of the new energy industry, the demand for battery-grade lithium carbonate is also increasing. As the main ore source of high-purity lithium chemicals, spodumene has put forward higher requirements for product purity, material and energy consumption in the smelting process, and by-product emissions in the extraction process. The processes for producing lithium carbonate from spodumene include sulfuric acid method, limestone roasting method, sulfate roasting method, etc. Among them, sulfuric acid method is currently the commonly used process for extracting lithium from spodumene. The spodumene sulfuric acid method for extracting lithium from spodumene mainly uses two-stage roasting, that is, high-temperature transformation roasting (≈1150℃) connected with sulfuric acid acid roasting (>250℃). After the roasted materials are soaked in water, they are connected to the back-end lithium extraction. The leached slurry needs to be neutralized, resulting in the current sulfur co-existence of spodumene smelting slag. The SO3 content in spodumene smelting slag is 10%-20%, which limits the large-scale application of spodumene smelting slag.

[0003] At present, the method for separating sulfur from spodumene smelting slag is mainly through wet dissolution to achieve deep removal of impurities. CN202410530351.7 discloses a new process for desulfurization of spodumene smelting slag using EDTA. The process uses the final solid waste residue obtained in the process of water leaching lithium after spodumene is roasted with sulfuric acid as raw material, and adds the prepared EDTA solution to the smelting slag containing about 10% calcium sulfate, so that the raw material and the EDTA solution react fully to achieve desulfurization of the smelting slag, and finally the filtrate is subjected to rotary evaporation precipitation, and the EDTA solution is recovered and recycled. CN202310532112.0 discloses a method for comprehensive resource utilization of spodumene smelting slag, which can recycle lithium, tantalum and niobium in lithium slag. The process is simple, efficient and environmentally friendly, and significantly improves the comprehensive utilization rate of lithium resources. It not only realizes the de-ironization of slag, but also recovers tantalum, niobium and lithium in slag, and can also obtain a silicon aluminum fine powder product for the glass fiber industry and an additional product gypsum. CN202321125517.4 discloses a spodumene smelting slag resource comprehensive utilization system, which includes a lithium liquid circulation leaching unit, a gypsum recovery unit, an iron recovery unit, a tantalum niobium recovery unit and a silicon aluminum recovery unit to achieve the comprehensive utilization of spodumene smelting slag. The ideas and methods proposed in the above study achieve the full stripping of calcium sulfate in spodumene smelting slag, but in order to completely realize the separation of spodumene smelting slag sulfur, the innovation of the existing spodumene lithium extraction process is an effective way to completely solve the problem of spodumene smelting slag sulfur.

[0004] Therefore, how to disclose a method for reducing the amount and harm of spodumene smelting slag at the source and directly preparing low-sulfur lithium smelting slag is a difficult problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of this, the present invention provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, so as to solve the problem that the smelting slag obtained from spodumene smelting has a high sulfur content and is difficult to utilize, and also solves the problem of the complexity of the existing slag sulfur separation method.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, comprising roasting and transforming spodumene and acidifying and roasting with sulfuric acid to obtain acidified roasted spodumene, and further comprising the following steps:

[0008] The acidified roasted spodumene is mixed with water for leaching, and the solid-liquid separation is performed to obtain a sulfur-containing lithium-rich solution and a solid phase. The solid phase is washed to obtain a low-sulfur lithium smelting slag.

[0009] Preferably, the mass ratio of the acid-calcined spodumene to water is 1:1-10.

[0010] Preferably, the leaching time is 10 to 120 minutes, and the leaching temperature is 0 to 50°C.

[0011] Preferably, the washing comprises single-stage washing or multi-stage countercurrent washing.

[0012] Preferably, during the washing process, the mass ratio of the solid phase to the washing liquid is 1:1-10, and the washing temperature is 20-70°C.

[0013] Preferably, the sulfur-containing lithium-rich solution is mixed with calcium carbonate to obtain a mixed solution for reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a calcium sulfate byproduct and a lithium-rich solution.

[0014] Preferably, the amount of calcium carbonate in the mixed solution is 103-115% of the amount used to adjust the mixed solution to a neutral state.

[0015] The invention discloses a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product. The spodumene is subjected to roasting transformation and sulfuric acid acid roasting, the acid roasted spodumene is wet leached, the acidolysis slurry after water leaching is directly subjected to solid-liquid separation, the leached slag (solid phase) is washed to obtain smelting slag whose mineral phase composition is mainly aluminum silicon minerals, providing raw materials for the preparation of aluminum silicon series products; the lithium-containing solution (liquid phase) obtained by solid-liquid separation is neutralized and precipitated to remove impurities, to obtain a calcium sulfate by-product and a lithium-rich solution, providing raw materials for the back-end lithium series products.

[0016] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Compared with the traditional two-stage lithium extraction process of spodumene, the present invention directly performs acid filtration on the acid-lysed slurry, thereby avoiding the problem of the coexistence of spodumene smelting slag and calcium sulfate, and completely solving the problem of the difficulty in utilizing spodumene smelting slag from the source. At the same time, lithium-rich solution and calcium sulfate by-products are produced, which greatly reduces the emission of spodumene smelting slag and the risk of environmental toxicity.

[0018] 2. The present invention provides high-quality raw materials for lithium products. While reducing the discharge of spodumene smelting slag, the calcium sulfate obtained by subsequent neutralization can be used as a by-product, greatly reducing the discharge of spodumene smelting slag and the risk of environmental toxicity. The spodumene acid hydrolysis slurry is directly filtered, which is a simple process with great operational flexibility, achieving the common development of economic and environmental benefits. DETAILED DESCRIPTION

[0019] The present invention provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, comprising roasting and transforming spodumene and acidifying and roasting with sulfuric acid to obtain acidified roasted spodumene, and further comprising the following steps:

[0020] The acidified roasted spodumene is mixed with water for leaching, and the solid-liquid separation is performed to obtain a sulfur-containing lithium-rich solution and a solid phase. The solid phase is washed to obtain a low-sulfur lithium smelting slag.

[0021] In the present invention, the spodumene concentrate is preferably roasted and transformed in a rotary kiln at 950-1150°C, the roasted and transformed ore is cooled, mixed with a sufficient amount of sulfuric acid, and roasted by sulfuric acid acidification at 200-300°C in an acidification rotary kiln to achieve mineral phase reconstruction.

[0022] In the present invention, the temperature of the calcination transformation can be specifically 980°C, 1000°C, 1050°C, 1100°C; the temperature of the sulfuric acid acidification calcination can be specifically 220°C, 240°C, 250°C, 260°C, 280°C.

[0023] In the present invention, the roasting transformation and sulfuric acid acidification roasting adopt conventional processes.

[0024] In the present invention, the mass ratio of the acid-calcined spodumene to water is 1:1-10, preferably 1:2-8, more preferably 1:4-6, and further preferably 1:5.

[0025] In the present invention, the leaching time is 10 to 120 min, specifically 20 min, 40 min, 50 min, 60 min, 80 min, 100 min; the leaching temperature is 0 to 50°C, specifically 5°C, 10°C, 20°C, 30°C, 40°C.

[0026] In the present invention, the washing includes single-stage washing or multi-stage countercurrent washing.

[0027] In the present invention, the multi-stage countercurrent washing includes two-stage countercurrent washing or three-stage countercurrent washing.

[0028] In the present invention, the mass ratio of the solid phase to the washing liquid during the washing process is 1:1-10, preferably 1:2-8, further preferably 1:4-6, and further preferably 1:5; the washing temperature is 20-70°C, specifically 30°C, 40°C, 50°C, 60°C.

[0029] In the present invention, a sulfur-containing lithium-rich solution is mixed with calcium carbonate to obtain a mixed solution for reaction, and after the reaction is completed, a calcium sulfate byproduct and a lithium-rich solution are obtained by solid-liquid separation.

[0030] In the present invention, the amount of calcium carbonate in the mixed solution is 103-115% of the amount used to adjust the mixed solution to a neutral state.

[0031] In the present invention, the amount of calcium carbonate added is in excess of the theoretically calculated value required to neutralize the liquid phase to neutrality.

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, the method comprising the following steps:

[0035] (1) 200 g of spodumene concentrate was calcined at 1050° C. After the calcined ore was cooled, it was mixed with 98% concentrated sulfuric acid at a mass ratio of 1:1.4, and acid-roasted at 250° C. to achieve mineral phase reconstruction, thereby obtaining acid-roasted spodumene whose mineral phase composition was mainly lithium sulfate.

[0036] (2) The acidified roasted spodumene is mixed with water for wet leaching, the solid-liquid mass ratio of the wet leaching is 1:2, the reaction time of the wet leaching is 30 minutes, the reaction temperature is 25°C, the acid leaching slurry is solid-liquid separated to obtain spodumene smelting slag, the spodumene smelting slag is washed with water to obtain low-sulfur lithium smelting slag, the washing water is returned to the wet leaching, the solid-liquid mass ratio of the washing is 1:2, the washing water temperature is 50°C, and the washing method is three-stage countercurrent washing.

[0037] (3) Add calcium carbonate (adjusted to 105% of the neutral amount) to the lithium-containing solution to neutralize and remove impurities, thereby obtaining a calcium sulfate byproduct and a lithium-rich solution.

[0038] The SO3 content in the low-sulfur lithium smelting slag was tested by X-ray fluorescence spectroscopy. The SO3 content of the spodumene smelting slag obtained in this embodiment was 0.52%.

[0039] Example 2

[0040] This embodiment provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, the method comprising the following steps:

[0041] (1) 200 g of spodumene concentrate was calcined at 1050° C. After the calcined ore was cooled, it was mixed with 98% concentrated sulfuric acid at a mass ratio of 1:1.4, and acid-roasted at 250° C. to achieve mineral phase reconstruction, thereby obtaining acid-roasted spodumene whose mineral phase composition was mainly lithium sulfate.

[0042] (2) The acidified roasted spodumene is mixed with water for wet leaching, the solid-liquid mass ratio of the wet leaching is 1:1, the reaction time of the wet leaching is 15 minutes, the reaction temperature is 30°C, the acid leaching slurry is solid-liquid separated to obtain spodumene smelting slag, the spodumene smelting slag is washed with water to obtain low-sulfur lithium smelting slag, the washing water is returned to the wet leaching, the solid-liquid mass ratio of the washing is 1:1, the washing water temperature is 60°C, and the washing method is single-stage washing.

[0043] (3) Add calcium carbonate (adjusted to 105% of the neutral amount) to the lithium-containing solution to neutralize and remove impurities, thereby obtaining a calcium sulfate byproduct and a lithium-rich solution.

[0044] The SO3 content in the low-sulfur lithium smelting slag was tested by X-ray fluorescence spectroscopy. The SO3 content of the spodumene smelting slag obtained in this embodiment was 1.4%.

[0045] Example 3

[0046] This embodiment provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, the method comprising the following steps:

[0047] (1) The spodumene concentrate is transformed by high-temperature roasting and roasted by sulfuric acid acid to achieve mineral phase reconstruction, thereby obtaining acid-roasted spodumene whose mineral phase composition is mainly lithium sulfate.

[0048] (2) The acidified roasted spodumene is mixed with water for wet leaching, the solid-liquid mass ratio of the wet leaching is 1:4, the reaction time of the wet leaching is 20 minutes, the reaction temperature is 20°C, the acid leaching slurry is solid-liquid separated to obtain spodumene smelting slag, the spodumene smelting slag is washed with water to obtain low-sulfur lithium smelting slag, the washing water is returned to the wet leaching, the solid-liquid mass ratio of the washing water is 1:4, the washing water temperature is 40°C, and the washing method is two-stage countercurrent washing.

[0049] (3) Add calcium carbonate (adjusted to 110% of the neutral amount) to the lithium-containing solution to neutralize and remove impurities, thereby obtaining a calcium sulfate byproduct and a lithium-rich solution.

[0050] The SO3 content in the low-sulfur lithium smelting slag was tested by X-ray fluorescence spectroscopy. The SO3 content of the spodumene smelting slag obtained in this embodiment was 1.36%.

[0051] Comparative Example 1

[0052] This embodiment provides a method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, the method comprising the following steps:

[0053] (1) 200 g of spodumene concentrate was calcined at 1050° C. After the calcined ore was cooled, it was mixed with 98% concentrated sulfuric acid at a mass ratio of 1:1.4, and acid-roasted at 250° C. to achieve mineral phase reconstruction, thereby obtaining acid-roasted spodumene whose mineral phase composition was mainly lithium sulfate.

[0054] (2) The acidified roasted spodumene is mixed with water for wet leaching, the solid-liquid mass ratio of the wet leaching is 1:2, the reaction time of the wet leaching is 30 minutes, the reaction temperature is 15°C, calcium carbonate is directly added to the acid leaching slurry for neutralization (adjusted to 105% of the neutral dosage), and then the leached slurry (the solid after filtering and washing the leaching slurry is the leaching residue) is directly filtered and washed, the solid-liquid mass ratio of the water washing is 1:2, the washing water temperature is 50°C, and the washing method is secondary countercurrent washing. The SO3 content in the spodumene smelting slag is 15.3% as tested by X-ray fluorescence spectroscopy.

[0055] Compared with Example 1, Comparative Example 1 compares the treatment of the acidolysis leaching slurry in step (2). Comparative Example 1 does not perform solid-liquid separation on the acidolysis leaching slurry, but directly performs neutralization and impurity removal in the acid leaching slurry. Comparative Example 1 causes a large amount of calcium sulfate to be doped in the spodumene smelting slag, resulting in the co-existence of slag sulfur in the spodumene smelting slag, which increases the amount of spodumene smelting slag produced while also increasing its environmental risks. At the same time, Comparative Example 1 cannot achieve effective utilization of the by-product calcium sulfate, which limits the large-scale comprehensive utilization of spodumene smelting slag.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product, comprising roasting and transforming spodumene and acidifying and roasting with sulfuric acid to obtain acidified roasted spodumene, characterized in that: The following steps are also included: The acidified roasted spodumene is mixed with water for leaching, and the solid-liquid separation is performed to obtain a sulfur-containing lithium-rich solution and a solid phase. The solid phase is washed to obtain a low-sulfur lithium smelting slag.

2. The method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product according to claim 1, characterized in that: The mass ratio of the acid-calcined spodumene to water is 1:1-10.

3. The method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product according to claim 2, characterized in that: The leaching time is 10 to 120 minutes, and the leaching temperature is 0 to 50°C.

4. The method for extracting lithium from spodumene with by-product low-sulfur lithium smelting slag according to any one of claims 1 to 3, characterized in that: The washing includes single-stage washing or multi-stage countercurrent washing.

5. The method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product according to claim 4, characterized in that: During the washing process, the mass ratio of the solid phase to the washing liquid is 1:1-10, and the washing temperature is 20-70°C.

6. The method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product according to claim 5, characterized in that: The sulfur-containing lithium-rich solution is mixed with calcium carbonate to obtain a mixed solution for reaction. After the reaction is completed, solid-liquid separation is performed to obtain a calcium sulfate byproduct and a lithium-rich solution.

7. The method for extracting lithium from spodumene and producing low-sulfur lithium smelting slag as a by-product according to claim 6, characterized in that: The amount of calcium carbonate in the mixed solution is 103-115% of the amount used to adjust the mixed solution to a neutral state.