Desulfurization method for spodumene smelting slag

Abstract

The invention discloses a spodumene smelting slag desulfurization method, and belongs to the technical field of solid waste resource utilization. The method provided by the invention comprises the following steps: S1, mixing spodumene smelting slag with water, and adjusting the pH value to 8-12.5 to prepare ore pulp; s2, a regulator is added into the ore pulp for pulp mixing, and first pulp is obtained; the adjusting agent comprises water glass, sodium citrate and ethylenediamine tetramethylene sodium phosphate; and S3, a collecting agent is added into the first slurry, flotation desulfurization operation is carried out, filtering and drying are carried out, and a gypsum product and desulfurized lithium slag are obtained. The desulfurization method is high in desulfurization efficiency and simple in technological process.

Description

Technical Field

[0001] The present application belongs to the technical field of solid waste resource utilization, and specifically relates to a desulfurization method for spodumene smelting slag. Background Art

[0002] Spodumene smelting slag is the solid waste produced after lithium extraction from spodumene ore. Common acid-based lithium extraction slag is the waste residue generated during the sulfuric acid process to produce lithium salts. This residue is produced after lithium ore undergoes high-temperature roasting, acid roasting, atmospheric pressure water leaching, and solid-liquid separation. Its main components are aluminosilicates, quartz, and gypsum. According to statistics, spodumene extraction produces approximately 8-10 tons of lithium slag for every ton of lithium carbonate produced (CN118847346A). Most of this slag is dumped or landfilled, which not only wastes resources but also poses environmental risks. Currently, the primary resource utilization of spodumene smelting slag is concentrated in the traditional building materials industry, such as low-value-added products like concrete, expanded clay, and unfired bricks. However, in these applications, the valuable metal elements (such as residual lithium, tantalum, and niobium) and gypsum components in the slag are not effectively recovered or reused at a high value. With the rapid growth of lithium slag, the building materials industry is nearing capacity to absorb it. Therefore, finding ways to maximize the value of spodumene smelting slag is becoming increasingly urgent. Removing gypsum from the slag and reducing its sulfur content are prerequisites for this high-value utilization. Currently, existing desulfurization methods suffer from low separation efficiency, a limited number of reagents, and complex operations, making them difficult to meet the needs of industrial and large-scale processing.

[0003] Therefore, there is an urgent need to develop a desulfurization method with high desulfurization efficiency and simple process flow. Summary of the Invention

[0004] In view of this, the present application provides a method for desulfurization of spodumene smelting slag, which has high desulfurization efficiency and simple process flow, can achieve effective separation of gypsum and silicate in lithium slag, provide raw material basis for the subsequent preparation of high value-added hemihydrate gypsum products and high-quality aluminum silicon powder, and provide an efficient technical means for the field of resource utilization of spodumene smelting slag.

[0005] In a first aspect, the present application provides a method for desulfurization of spodumene smelting slag, comprising the following steps: S1. Mixing spodumene smelting slag with water and adjusting the pH value to 8-12.5 to prepare slurry; S2, adding a conditioning agent to the slurry to adjust the slurry to obtain slurry 1; the conditioning agent includes water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate; S3, adding a collector to the slurry 1, performing flotation desulfurization operation, filtering, and drying to obtain gypsum products and desulfurized lithium slag.

[0006] By adopting the above technical solution, the spodumene smelting slag desulfurization method of the present application has high desulfurization efficiency and simple process flow, and can realize the effective separation of gypsum and silicate in lithium slag. Step S1 of the present application adjusts the pH value to 8~12.5. The alkaline environment not only helps to evenly disperse the mineral particles in the water, but also provides suitable conditions for subsequent chemical reactions. Step S2 adds a regulator composed of water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate in an alkaline environment, which can react with the metal cations in the silicate mineral lattice to form a complex, effectively inhibit the floating of silicates, and make gypsum the main foam product, thereby realizing efficient flotation desulfurization of lithium slag. Step S3 adds a collector, which selectively enhances the hydrophobicity of the gypsum, making it easier to float out, thereby realizing the effective separation of gypsum and silicate.

[0007] This application, under specific alkaline conditions, uses a specific composition of adjusting agents to significantly improve the selectivity and efficiency of flotation. The entire process is simple and easy to operate, requiring no complex pre- or post-treatment steps, and has promising industrial application prospects. The method provided by this application has high desulfurization efficiency, a wide variety of reagents, and good adaptability. It solves the problems of low separation efficiency and a single reagent in traditional desulfurization methods, providing a highly efficient technical means for the resource utilization of spodumene smelting slag.

[0008] Optionally, in step S1, the spodumene smelting slag includes CaO 5.79%~6.06%, SO3 6.03%~6.70%, and SiO2 58.64%~61.06%.

[0009] By adopting the above technical solution, the chemical composition of the spodumene smelting slag in the specific range of the present application provides a good mineral basis for flotation, which is conducive to the effective separation of gypsum and silicate by flotation.

[0010] Optionally, in step S1, the pH value is adjusted to 8-11.

[0011] Optionally, in step S1, the mass concentration of the slurry is 27% to 33%.

[0012] By adopting the above technical solution, the mass concentration of the slurry of the present application can ensure good dispersion of mineral particles, improve flotation efficiency, and is also conducive to controlling the dosage of reagents, avoiding waste and reducing costs.

[0013] Optionally, in step S1, adjusting the pH value to 8-12.5 includes: adding a pH adjuster to the slurry obtained by mixing the spodumene smelting slag with water, wherein the pH adjuster is selected from NaOH or CaO.

[0014] By adopting the above technical solution, the pH adjuster of the present application can accurately control the pH value, effectively support the entire flotation desulfurization process, ensure efficient separation between gypsum and silicate minerals, and thus obtain high-purity gypsum products and low-sulfur desulfurization lithium slag, providing a basis for the subsequent preparation of high-value-added products.

[0015] Optionally, in step S2, the mass ratio of water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate is (10~40): (1~10):1.

[0016] By adopting the above-mentioned technical solution, the specific mass ratio of water glass, sodium citrate, and sodium ethylenediamine tetramethylene phosphate in this application can achieve optimal inhibition of silicate minerals, thereby improving the selective recovery rate of gypsum, ensuring the production of high-quality gypsum products and low-sulfur desulfurized lithium slag. Furthermore, by flexibly adjusting the ratio of the three components, the process method of this application can be applied to a wider variety of slurries, increasing the process's flexibility and scope of application.

[0017] Optionally, in step S3, the collector includes at least one of dodecylamine, hexadecyltrimethylammonium bromide, sodium petroleum sulfonate, and sodium oleate.

[0018] By adopting the above technical solution, the collector of the present application can effectively enhance the hydrophobicity of gypsum particles, promote their attachment to bubbles and floating, thereby achieving efficient flotation and effective separation of gypsum and silicate minerals.

[0019] Optionally, the collector is dodecylamine and sodium petroleum sulfonate; the mass ratio of dodecylamine to sodium petroleum sulfonate is (2-10):1.

[0020] By adopting the above-mentioned technical solution, this application utilizes dodecylamine and sodium petroleum sulfonate as a composite collector system, leveraging their combined effects to enhance the hydrophobicity of gypsum while also providing excellent dispersion properties, helping to prevent the agglomeration of fine-grained minerals and thereby improving flotation efficiency. The specific mass ratio of dodecylamine to sodium petroleum sulfonate achieves optimal flotation efficiency while preventing the flotation of non-target minerals due to excessive dosage.

[0021] Optionally, in step S3, the flotation desulfurization operation includes one roughing process, one cleaning process, and two to three scavenging processes.

[0022] By adopting the above technical solution, the method of the present application achieves efficient separation of gypsum and silicate minerals by controlling the parameters of each step, simplifying the process and achieving the desired separation effect with only one cleaning step. This improves processing efficiency, reduces energy consumption and reagent consumption, and thus reduces costs. Two to three cleaning steps can maximize resource recovery and reduce resource waste and waste emissions.

[0023] Optionally, during the roughing, the amount of the collector is 50 g / t to 100 g / t; During the concentrating, the pH value of the slurry is adjusted to 9-11 by using the pH adjuster; During the sweeping, the total amount of the collector is 100 g / t to 150 g / t.

[0024] By adopting the above technical solution, the present application controls the amount of collector during roughing to promote the effective floating of target minerals, ensure the effective separation of gypsum, and avoid excessive use that causes the capture of non-target minerals, taking into account both economic and environmental requirements.

[0025] The pH value of the slurry during the concentration of the present application can further enhance the inhibitory effect on silicate minerals and effectively inhibit their floating.

[0026] The present application controls the amount of collector used during scavenging, which can ensure effective recovery of gypsum while avoiding non-selective flotation of non-target minerals, reducing reagent consumption and environmental load, and improving the economy of the overall flotation operation.

[0027] Optionally, the purity of the gypsum product is >90%; the SO3 content in the desulfurization lithium slag is <1%.

[0028] By adopting the above technical solution, the present application can achieve efficient separation of gypsum and silicate minerals, and ultimately obtain high-purity gypsum products (CaSO4 content>90%), providing raw materials for the preparation of high-value-added hemihydrate gypsum; at the same time, the SO3 content in the desulfurized lithium slag is reduced to <1%, which can be used to prepare high-value-added aluminum silicon powder, significantly improving the resource utilization rate of spodumene smelting slag, reducing the risk of environmental pollution, and has important industrial application prospects.

[0029] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The spodumene smelting slag desulfurization method of the present application has high desulfurization efficiency and a simple process flow, and can effectively separate gypsum and silicate in lithium slag.

[0030] 2. This application uses a specific composition of adjusters under specific alkaline conditions to significantly improve the selectivity and efficiency of flotation. The entire process is simple and easy to operate, without the need for complex pretreatment or post-treatment steps, and has good industrial application prospects.

[0031] 3. This application can achieve efficient separation of gypsum and silicate minerals, ultimately obtaining a high-purity gypsum product (CaSO4 content > 90%), which provides raw materials for the preparation of high-value-added hemihydrate gypsum; at the same time, the SO3 content in the desulfurized lithium slag is reduced to <1%, which can be used to prepare high-value-added aluminum silicon powder, significantly improving the resource utilization rate of spodumene smelting slag and reducing the risk of environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a process flow chart of the spodumene smelting slag desulfurization method of Example 1 of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0034] Flotation is a process that separates target minerals from gangue minerals by exploiting differences in their surface physical and chemical properties. It boasts low cost and high efficiency, making it an important mineral processing technology. CN116532235A discloses a method for the comprehensive resource utilization of spodumene smelting slag, comprising pulping, grinding, leaching, slurry preparation, flotation, magnetic separation, gravity separation, and weak magnetic separation to recover the various components in the spodumene smelting slag. This method utilizes flotation desulfurization, adjusts the slurry pH to 6-7, adds water glass, sodium hexametaphosphate, or CMC as a conditioning agent, and selects an anionic combined collector. After one roughing separation, three scavenging separations, and two concentrating steps, the foam product is concentrated and filtered to produce a gypsum product. This method requires two concentrating steps to obtain a gypsum product with a SO₃ content >40%, requiring high reagent dosages (>400 g / t of combined collector and 200-3000 g / t of conditioning agent), resulting in low separation efficiency and an irrational reagent system. CN114226413A, CN113976309A and CN118847346A all reported on lithium slag flotation desulfurization, but the types of adjusting agents used in these methods are relatively single, mostly using water glass, CMC, etc., and using fatty acid composite collectors. It takes 2 to 3 rounds of concentration to obtain a gypsum product with a SO3 content > 40%.

[0035] In summary, although the existing lithium slag flotation desulfurization method can achieve the separation of gypsum and other minerals to a certain extent, it has prominent problems such as low separation efficiency and a single type of reagents.

[0036] In order to solve the above problems, the present application proposes a method for desulfurization of spodumene smelting slag, comprising the following steps: S1. Mixing spodumene smelting slag with water and adjusting the pH value to 8-12.5 to prepare slurry; S2. Adding a conditioning agent to the ore pulp for slurry adjustment to obtain slurry 1; the conditioning agent includes water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate; S3. Adding a collector to slurry 1 for flotation desulfurization, filtering, and drying to obtain a gypsum product and desulfurized lithium slag. The inventors discovered that, under an alkaline environment, the addition of a conditioning agent consisting of water glass, sodium citrate, and sodium ethylenediaminetetramethylenephosphate can complex with the metal cations in the silicate mineral lattice, effectively inhibiting silicate flotation and making gypsum the primary foam product, thereby achieving efficient flotation desulfurization of lithium slag.

[0037] In some embodiments, in step S1, the spodumene smelting slag comprises 5.79% to 6.06% CaO, 6.03% to 6.70% SO₃, and 58.64% to 61.06% SiO₂. Controlling the composition of the spodumene smelting slag in the present application facilitates the effective separation of gypsum and silicate.

[0038] In some embodiments, in step S1, the pH value is adjusted to 8 to 11. The present application controls the pH value of the slurry to further improve the flotation desulfurization efficiency.

[0039] In some embodiments, in step S1, the mass concentration of the ore pulp is 27% to 33%. The present application controls the mass concentration of the ore pulp to further improve the flotation desulfurization efficiency.

[0040] In some embodiments, in step S1, adjusting the pH to 8-12.5 includes adding a pH adjuster to the slurry obtained by mixing spodumene smelting slag with water, wherein the pH adjuster is selected from NaOH or CaO. The present application further improves flotation desulfurization efficiency by controlling the pH of the slurry and selecting the pH adjuster.

[0041] In some embodiments, in step S2, the mass ratio of water glass, sodium citrate, and EDTP is (10-40): (1-10): 1. The present application controls the mass ratio of water glass, sodium citrate, and EDTP to further improve flotation desulfurization efficiency and inhibit the flotation of silicate minerals.

[0042] In some embodiments, in step S3, the collector includes at least one of dodecylamine, hexadecyltrimethylammonium bromide, sodium petroleum sulfonate, and sodium oleate. The selection of the collector in the present application further improves the flotation desulfurization efficiency.

[0043] In some embodiments, the collector is dodecylamine and sodium petroleum sulfonate. The compounding of the collectors in the present application further improves the flotation desulfurization efficiency.

[0044] In some embodiments, the mass ratio of dodecylamine to sodium petroleum sulfonate is (2-10): 1. The present application controls the mass ratio of dodecylamine to sodium petroleum sulfonate to further improve the flotation desulfurization efficiency.

[0045] In some embodiments, in step S3, the flotation desulfurization operation includes one roughing operation, one cleaning operation, and two to three scavenging operations. The present application controls the flotation desulfurization operation process, simplifies the process, improves processing efficiency, and reduces costs.

[0046] In some embodiments, the amount of collector used during roughing is 50 g / t to 100 g / t. The present application controls the amount of collector used during roughing, further improving the flotation desulfurization efficiency while suppressing the floating of non-target minerals.

[0047] In some embodiments, during the concentration, a pH adjuster is used to adjust the pH value of the pulp to 9 to 11. The present application controls the pH value of the pulp during the concentration, further improving the flotation desulfurization efficiency.

[0048] In some embodiments, the total amount of the collector used during scavenging is 100 g / t to 150 g / t. The present application controls the amount of collector used during scavenging to further improve the gypsum recovery rate and prevent non-target minerals from floating.

[0049] In some embodiments, the purity of the gypsum product is greater than 90%; the SO3 content in the desulfurized lithium slag is less than 1%. The purity of the gypsum product and the SO3 content in the desulfurized lithium slag of the present application significantly improve the resource utilization rate of spodumene smelting slag.

[0050] The scheme of the present application is described below with reference to the following specific examples. Unless otherwise specified, the raw materials used in the following examples are all from common commercial products, and the devices or equipment used are all purchased from conventional market sales channels. Specific embodiments Example 1 This embodiment provides a method for desulfurization of spodumene smelting slag, comprising the following steps: S1. Weigh 500 g of spodumene smelting slag from a company in Jiangxi Province into a 1.5 L flotation tank, add water and mix, adjust the slurry concentration to 27%, and stir for 5 minutes; add 3.2 kg / t NaOH and stir for 5 minutes, at which point the pH value is 9.2, to obtain a slurry; wherein the spodumene smelting slag contains 5.79% CaO, 6.22% SO3, and 60.12% SiO2; S2. Add 1000 g / t water glass, 100 g / t sodium citrate and 100 g / t sodium ethylenediaminetetramethylenephosphate to the ore pulp and stir for 5 minutes to obtain slurry 1; S3. Add 50 g / t of collector to slurry 1, stir for 5 minutes, and perform roughing. At this time, the pH value of the slurry is 9; then perform three scavenging, adding 50 g / t of collector for each scavenging, filter and dry the tailings after scavenging to obtain desulfurized lithium slag; combine the roughing and scavenging foams, transfer to a 0.75 L flotation tank, add 0.2 kg / t of NaOH, stir for 3 minutes, at this time, the pH value of the slurry is 10.5, perform concentrating, filter and dry the concentrated ore to obtain a gypsum product; wherein the collector is dodecylamine.

[0052] The flotation desulfurization results of Example 1 are shown in Table 1.

[0053] Table 1

[0054] Example 2 This embodiment provides a method for desulfurization of spodumene smelting slag, comprising the following steps: S1. Weigh 500g of spodumene smelting slag from a company in Jiangxi Province into a 1.5L flotation tank, add water and mix, adjust the slurry concentration to 33%, and stir for 5 minutes; add 8kg / t CaO and stir for 5 minutes, at which point the pH value is 12.5, to obtain a slurry; wherein the spodumene smelting slag contains 5.85% CaO, 6.03% SO3, and 61.06% SiO2; S2. Add 2000 g / t water glass, 500 g / t sodium citrate and 50 g / t sodium ethylenediaminetetramethylenephosphate to the ore pulp and stir for 5 minutes to obtain slurry 1; S3. Add 50 g / t of collector to slurry 1, stir for 5 minutes, and perform roughing. At this time, the pH value of the pulp is 12.2; then perform two scavenging, adding 50 g / t of collector in both scavenging, filter and dry the tailings after scavenging to obtain desulfurized lithium slag; combine the roughing and scavenging foams, transfer to a 0.75 L flotation tank, add 0.4 kg / t of CaO, stir for 3 minutes, at this time, the pH value of the pulp is 11, and perform concentrating. Filter and dry the concentrate after concentrating to obtain a gypsum product; wherein the collector is dodecylamine.

[0055] The flotation desulfurization results of Example 2 are shown in Table 2.

[0056] Table 2

[0057] Example 3 This embodiment provides a method for desulfurization of spodumene smelting slag, comprising the following steps: S1. Weigh 500 g of spodumene smelting slag from a company in Jiangxi Province into a 1.5 L flotation tank, add water and mix, adjust the slurry concentration to 33%, and stir for 5 minutes; add 1 kg / t NaOH and stir for 5 minutes, at which point the pH value is 8.2, to obtain a slurry; wherein the spodumene smelting slag contains CaO 6.06%, SO3 6.41%, and SiO2 60.50%; S2. Add 1000 g / t water glass, 400 g / t sodium citrate and 50 g / t sodium ethylenediaminetetramethylenephosphate to the ore pulp and stir for 5 minutes to obtain slurry 1; S3. Add 100 g / t of collector to slurry 1, stir for 5 minutes, and perform roughing. At this time, the pH value of the slurry is 8; then perform two scavenging, adding 50 g / t of collector in both scavenging, filtering and drying the tailings after scavenging to obtain desulfurized lithium slag; combine the roughing and scavenging foams, transfer to a 0.75 L flotation tank, add 0.2 kg / t of NaOH, stir for 3 minutes, at this time, the pH value of the slurry is 9, and perform concentrating. Filter and dry the concentrated ore to obtain a gypsum product; wherein the collector is dodecylamine.

[0058] The flotation desulfurization results of Example 3 are shown in Table 3.

[0059] Table 3

[0060] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that NaOH, CaO and a regulator are not added. The specific steps are as follows: S1. Weigh 500 g of spodumene smelting slag from a company in Jiangxi Province into a 1.5 L flotation tank, add water and mix, adjust the slurry concentration to 33%, and stir for 5 minutes. At this time, the pH value is 7.8 to obtain a slurry; wherein the spodumene smelting slag contains CaO 5.82%, SO3 6.70%, and SiO2 58.64%; S2. Add 50 g / t of collector to the pulp, stir for 5 minutes, and perform roughing. At this time, the pH value of the pulp is 7.6; then perform three scavenging, adding 50 g / t of collector for each scavenging, filter and dry the tailings after scavenging to obtain desulfurized lithium slag; combine the roughing and scavenging foams, transfer to a 0.75 L flotation tank, and the pH value of the pulp during the scavenging is 7.5. The concentrated ore is filtered and dried to obtain a gypsum product; wherein the collector is dodecylamine.

[0061] The flotation desulfurization results of Comparative Example 1 are shown in Table 4.

[0062] Table 4

[0063] It can be seen from the data in Tables 1 to 4 that the grade of CaO+SO3 in the concentrates of Examples 1 to 3 is >90%, and the grade of SiO2 is low, indicating that the method of the present application has high desulfurization efficiency, realizes effective separation of gypsum and silicate in lithium slag, and the gypsum product has high purity (CaSO4 content >90%); and the grade of SO3 in the tailings of Examples 1 to 3 is less than 1%, that is, the SO3 content in the desulfurized lithium slag is <1%, further illustrating that the method of the present application has high desulfurization efficiency.

[0064] In Comparative Example 1, no NaOH, CaO and adjusting agent are added. In the final concentrate, the grade of CaO+SO3 is significantly reduced, that is, the CaSO4 content is reduced, and the grade of SiO2 is significantly increased, indicating that Comparative Example 1 cannot achieve effective separation of gypsum and silicate in lithium slag.

[0065] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in step S2 of Comparative Example 2, the adjusting agent does not contain sodium citrate, and sodium citrate is replaced by water glass of equal mass.

[0066] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in step S2 of Comparative Example 3, the adjusting agent does not contain sodium ethylenediaminetetramethylenephosphate, and sodium ethylenediaminetetramethylenephosphate is replaced by an equal mass of sodium citrate.

[0067] Examples 4 to 10 Example 4 The difference between Example 4 and Example 1 is that in step S1 of Example 4, the total amount of water glass, sodium citrate and EDTP sodium phosphate remains unchanged at 1200 g / t, but the mass ratio of water glass, sodium citrate and EDTP sodium phosphate is 25:5:1.

[0068] Example 5 The difference between Example 5 and Example 1 is that in step S1 of Example 5, the total amount of water glass, sodium citrate and EDTP sodium phosphate remains unchanged at 1200 g / t, but the mass ratio of water glass, sodium citrate and EDTP sodium phosphate is 40:10:1.

[0069] Example 6 The difference between Example 6 and Example 1 is that in step S3 of Example 6, the collecting agent is hexadecyltrimethylammonium bromide.

[0070] Example 7 The difference between Example 7 and Example 1 is that in step S3 of Example 7, the collector is dodecylamine and sodium petroleum sulfonate in a mass ratio of 2:1.

[0071] Example 8 The difference between Example 8 and Example 1 is that in step S3 of Example 8, the collector is dodecylamine and sodium petroleum sulfonate in a mass ratio of 6:1.

[0072] Example 9 The difference between Example 9 and Example 1 is that in step S3 of Example 9, the collector is dodecylamine and sodium petroleum sulfonate in a mass ratio of 10:1.

[0073] Example 10 The difference between Example 10 and Example 1 is that in step S1 of Example 10, the pH value of the slurry is adjusted to 11. The specific steps are as follows: S1. Weigh 500 g of spodumene smelting slag from a company in Jiangxi Province into a 1.5 L flotation tank, add water and mix, adjust the slurry concentration to 27%, and stir for 5 minutes; add 5 kg / t NaOH and stir for 5 minutes, at which point the pH value is 11, to obtain a slurry; wherein the spodumene smelting slag contains 5.79% CaO, 6.22% SO3, and 60.12% SiO2; S2. Add 1000 g / t water glass, 100 g / t sodium citrate and 100 g / t sodium ethylenediaminetetramethylenephosphate to the ore pulp and stir for 5 minutes to obtain slurry 1; S3. Add 50 g / t of collector to slurry 1, stir for 5 minutes, and perform roughing. At this time, the pH value of the slurry is 10.4; then perform three scavenging, adding 50 g / t of collector for each scavenging, filter and dry the tailings after scavenging to obtain desulfurized lithium slag; combine the roughing and scavenging foams, transfer to a 0.75 L flotation tank, add 0.1 kg / t of NaOH, stir for 3 minutes, at this time, the pH value of the slurry is 10.5, perform concentrating, filter and dry the concentrated ore to obtain a gypsum product; wherein the collector is dodecylamine.

[0074] The flotation desulfurization results of Comparative Examples 2-3 and Examples 4-10 are shown in Table 5.

[0075] Table 5

[0076] From the test results in Table 5, it can be seen that the adjuster of Comparative Example 2 does not contain sodium citrate, and the adjuster of Comparative Example 3 does not contain sodium ethylenediaminetetramethylenephosphate. The grades of CaO and SO3 in the concentrate are both reduced, the purity of the gypsum product is reduced, the grade of SiO2 is significantly increased, and the grade of SO3 in the tailings is increased, that is, the gypsum and silicate cannot be effectively separated.

[0077] The difference between Example 4 and Example 5 and Example 1 is that the mass ratios of water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate are different. Among them, Example 5 has the highest desulfurization efficiency and the best separation effect of gypsum and silicate.

[0078] In Example 6, the collector is replaced with hexadecyltrimethylammonium bromide, which can also achieve good desulfurization efficiency and effectively separate gypsum and silicate.

[0079] Examples 7-9 differ from Example 1 in that the single collector, dodecylamine, is replaced with a combined system of dodecylamine and sodium petroleum sulfonate. Compared to Example 1, the concentrates of Examples 7-9 exhibit increased CaO and SO3 grades, decreased SiO2 grades, and lower SO3 grades in the tailings. This improves desulfurization efficiency and the separation of gypsum from silicates. Among them, Example 8 achieves the highest desulfurization efficiency and the best separation of gypsum from silicates.

[0080] In step S1 of Example 10, the pH value of the slurry is adjusted to 11, the grades of CaO and SO3 in the concentrate increase, the grade of SiO2 decreases, and the grade of SO3 in the tailings decreases, which improves the desulfurization efficiency and the separation effect of gypsum and silicate.

[0081] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for desulfurization of spodumene smelting slag, characterized in that: The steps include: S1. Mixing spodumene smelting slag with water and adjusting the pH value to 8-12.5 to prepare slurry; S2, adding a conditioning agent to the slurry to adjust the slurry to obtain slurry 1; the conditioning agent includes water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate; S3, adding a collector to the slurry 1, performing flotation desulfurization operation, filtering, and drying to obtain gypsum products and desulfurized lithium slag.

2. The method according to claim 1, wherein In step S1, the spodumene smelting slag includes CaO 5.79%~6.06%, SO3 6.03%~6.70%, and SiO2 58.64%~61.06%.

3. The method according to claim 1, characterized in that In step S1, the mass concentration of the slurry is 27% to 33%.

4. The method according to claim 1, wherein In the step S1, adjusting the pH value to 8-12.5 includes: adding a pH adjuster to the slurry obtained by mixing the spodumene smelting slag with water, wherein the pH adjuster is selected from NaOH or CaO.

5. The method according to claim 1, wherein In step S2, the mass ratio of water glass, sodium citrate and sodium ethylenediaminetetramethylenephosphate is (10-40): (1-10):

1.

6. The method according to claim 1, characterized in that In step S3, the collector includes at least one of dodecylamine, hexadecyltrimethylammonium bromide, sodium petroleum sulfonate, and sodium oleate.

7. The method according to claim 6, characterized in that The collector is dodecylamine and sodium petroleum sulfonate; the mass ratio of dodecylamine to sodium petroleum sulfonate is (2-10):

1.

8. The method according to claim 1, characterized in that In step S3, the flotation desulfurization operation includes one roughing operation, one cleaning operation, and two to three scavenging operations.

9. The method according to claim 8, characterized in that During the roughing, the amount of the collector is 50g / t~100g / t; During the concentrating, the pH value of the slurry is adjusted to 9-11 by using the pH adjuster; During the sweeping, the total amount of the collector is 100 g / t to 150 g / t.

10. The method according to claim 1, characterized in that The purity of the gypsum product is greater than 90%; the SO3 content in the desulfurized lithium slag is less than 1%.

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