Separation and recovery process for scandium, manganese and iron in iron-manganese slag

Abstract

The invention discloses a process for separating and recycling scandium, manganese and iron in iron-manganese slag, and belongs to the technical field of metallurgical engineering and comprehensive utilization of secondary resources. The method comprises the following steps: crushing the iron and manganese slag, mixing the crushed iron and manganese slag with a chlorinating agent and a molten salt medium, and carrying out chlorination reaction at 600-850 DEG C, so that iron and manganese are converted into chlorides to volatilize, and scandium is enriched in the slag; the volatile gas is subjected to multi-stage gradient condensation, and manganese and iron concentrates are respectively recovered in different temperature intervals; and leaching-extracting the chlorination residues to obtain a scandium-rich substance. According to the method, source separation and collaborative recovery of iron, manganese and scandium are achieved through pyrogenic process chlorination-condensation, the problems that in a traditional wet process, metal interferes with one another, the process is long, and pollution is heavy are solved, and the method has the advantages of being short in process, small in pollution and high in recycling degree.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical engineering and comprehensive utilization of secondary resources, and particularly relates to a process for separating and recovering scandium, manganese and iron from iron-manganese slag. BACKGROUND

[0002] Iron-manganese slag is an industrial waste residue produced in the production of vanadium-titanium magnetite beneficiation and smelting process and the extraction process of non-ferrous metals, and mainly contains iron, manganese and a small amount of rare and precious metals (Sc). With the rapid development of the steel and new energy industries, the stockpiling of iron-manganese slag is increasing year by year, and its large accumulation not only occupies land resources, but also may cause environmental pollution due to the leaching of heavy metals. Iron-manganese slag is rich in scandium, iron and manganese resources, making it have significant recycling value. However, the resource utilization of iron-manganese slag mainly faces the following challenges: first, the occurrence state of scandium is complex and the content is low, and when traditional wet leaching is used, a large amount of coexisting elements such as iron and manganese will be dissolved out first, which seriously interferes with the selective extraction and enrichment of scandium, resulting in low scandium recovery rate and a large amount of acid wastewater containing heavy metals; second, iron and manganese elements have similar chemical properties, and it is difficult and costly to separate them in a wet system, resulting in low added value of the recovered products. The existing technical routes are difficult to economically and efficiently separate and recover iron and manganese while recovering scandium.

[0003] CN115948656A, CN115974128A and the like use titanium white waste acid or mixed acid leaching, combined with solvent extraction and multi-stage stripping-roasting process to extract high-purity scandium oxide. Although this method can obtain high-purity scandium oxide, its essence is to acid-dissolve all valuable and impurity elements in the iron-manganese slag, and then separate and purify scandium from the complex mixed solution. This not only leads to huge reagent consumption, a large amount of waste liquid, and a long process, but more importantly, iron and manganese elements are mixed together in the leaching solution, which is difficult to economically separate and recover, and in essence, is discarded as impurities, resulting in resource waste. In addition, CN115896465A and CN115896464A use an acid leaching-extraction-roasting process to recover scandium from a by-product of molten salt chlorination comprehensive utilization, which also has problems such as complex extraction system, multiple stripping and transformation steps, high scandium recovery cost, and the like, and fails to achieve the simultaneous recovery of iron and manganese.

[0004] The existing technologies are limited to the wet process of "mixed leaching first and separation and purification later", and fail to achieve the directional separation and pre-concentration of multi-metal components from the source. Therefore, developing a process that can achieve efficient separation and enrichment of iron, manganese and scandium in the initial reaction stage, thereby greatly simplifying the subsequent process and avoiding a large amount of wastewater discharge, is crucial to improving the overall resource utilization efficiency of iron-manganese slag. SUMMARY

[0005] The technical problem to be solved by the present application is the complexity and low efficiency of the existing resource recycling process for iron-manganese slag.

[0006] To achieve the above-mentioned application purposes, the technical scheme adopted by the present application is as follows.

[0007] In a first aspect, the present application provides a process for separating and recovering scandium, manganese and iron from iron-manganese slag, comprising the following steps: S1. crushing the iron-manganese slag, then mixing it with a chlorinating agent and a molten salt medium to obtain a mixture; S2. performing a chlorination reaction on the mixture at 600-850℃ to obtain volatile substances and chlorination residues; S2-1. collecting manganese and iron concentrates from the volatile substances through multi-stage condensation; S2-2. obtaining a scandium-containing leaching solution from the chlorination residues through solvent leaching and solid-liquid separation; S3. obtaining a scandium-rich substance from the scandium-containing leaching solution through solvent extraction.

[0008] In the above step S1, the iron-manganese slag is crushed to a particle size of 100-200 mesh.

[0009] In the above step S1, the chlorinating agent is chlorine and / or calcium chloride.

[0010] Further, the chlorinating agent is chlorine, and the amount of chlorine introduced is 1.5-3.0 mol / kg of iron-manganese slag.

[0011] Further, the chlorinating agent is calcium chloride, and the amount of calcium chloride added is 8.0-15.0 mol / kg of iron-manganese slag.

[0012] Further, the chlorinating agent is chlorine and calcium chloride, the amount of chlorine introduced is 0.2-1.0 mol / kg of iron-manganese slag, the amount of calcium chloride added is 0.5-3.0 mol, and the molar ratio of chlorine to calcium chloride is 1:1-4.

[0013] In the above step S1, the molten salt medium is a NaCl-KCl composite molten salt, the molar ratio of NaCl to KCl in the NaCl-KCl composite molten salt is 1:0.8-1.0, and the mass ratio of iron-manganese slag to NaCl-KCl composite molten salt is 1:2-5.

[0014] In the above step S2, the chlorination reaction is heated at a rate of 5-10℃ / min to 600-850℃ for 1-3h.

[0015] In the above step S2-1, the multi-stage condensation is as follows: in the first-stage condensation section, the temperature is controlled at 650-750℃, and MnCl2-rich manganese concentrate is recovered by condensation; in the second-stage condensation section, the temperature is controlled at 750-850℃, and FeCl2 / FeCl3-rich iron concentrate is recovered by condensation.

[0016] Further, the first-stage condensing section is controlled at a temperature of 700±20 DEG C, and the second-stage condensing section is controlled at a temperature of 800±20 DEG C.

[0017] In the step S2-2, the solid-liquid ratio of the residue to the solvent in the solvent leaching is 1g:4-10mL, the solvent is water or a hydrochloric acid solution with a concentration of 0.5-2.0mol / L, the leaching time is 70-90min, and the leaching temperature is 25-50 DEG C.

[0018] In the step S3, the solvent extraction is performed with the aqueous phase being the leaching solution containing scandium and the organic phase containing the extractant P204, the synergistic agent TBP and the diluent; wherein, the concentration of P204 is 5-20vol.% and the concentration of TBP is 5-20vol.% based on the total volume of the organic phase, and the rest is the diluent; the extraction time is 1-10min, and the phase ratio O / A is 1 / 1-1 / 5.

[0019] Further, the diluent is any one of sulfonated kerosene, n-heptane, toluene, xylene and isoamyl alcohol.

[0020] The iron-manganese slag resourceization process based on the molten salt chlorination method provided by the application realizes the directional conversion and separation of iron, manganese and scandium at the source compared with the traditional wet treatment method.

[0021] The multi-stage gradient condensation technology is used to collect manganese and iron components in different temperature ranges, which fundamentally avoids the problems of difficult separation and mutual interference of iron, manganese and scandium in the traditional wet process, and realizes the collaborative recovery of the three valuable metals from a single waste residue.

[0022] The waste residue is fully converted into high-value-added products, the recovered manganese can be used as high-quality raw materials in the field of new energy batteries, the recovered iron can be directly used in the metallurgical industry, and the residue phase enriched with scandium provides high-quality purification raw materials for the subsequent preparation of high-purity scandium oxide, greatly reducing the final extraction cost of scandium. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application clearer, the present application will be further described in detail below in conjunction with embodiments. Unless otherwise defined, all technical terms used herein have the same meanings as understood by those skilled in the art.

[0024] A separation and recovery process of scandium, manganese and iron in iron-manganese slag, which utilizes high-temperature chlorination reaction to convert the metals into chloride vapor, and then realizes selective separation and enrichment by stepwise condensation according to the boiling point difference. The process of the separation and recovery process can be divided into four main stages: raw material pretreatment, chlorination volatilization, gradient condensation separation and slag phase treatment, and specifically comprises the following steps.

[0025] The main chemical components of the iron-manganese slag in the present application are as follows in terms of mass percentage: Fe 20-40%, Mn 3-6%, Mg 3-5%, Ca 1.5-3.0%, Al 0.2-1.0%, Ti 0.4-1.0%, and Sc 0.01-0.1%.

[0026] Step one, raw material pretreatment: crushing the iron-manganese slag to 100-200 mesh, and then mixing with a chlorinating agent and a molten salt medium to obtain a mixture.

[0027] In an embodiment of the present application, the chlorinating agent is chlorine and / or calcium chloride. Chlorine has strong chlorination ability, fast reaction speed and high efficiency. When chlorine is used as the chlorinating agent, the amount of chlorine introduced is 1.5-3.0 mol / kg of the iron-manganese slag. Calcium chloride is easy to transport and operate, and can generate chlorine at high temperature. When calcium chloride is used as the chlorinating agent, the amount of calcium chloride added is 8.0-15.0 mol / kg of the iron-manganese slag. The combination of chlorine and calcium chloride can take into account both the reaction efficiency and the operational convenience. Therefore, preferably, when the chlorinating agent is chlorine and calcium chloride, the amount of chlorine introduced is 0.2-1.0 mol / kg of the iron-manganese slag, the amount of calcium chloride added is 0.5-3.0 mol / kg of the iron-manganese slag, and the molar ratio of chlorine to calcium chloride is 1:1-4.

[0028] In an embodiment of the present application, the molten salt medium is a NaCl-KCl composite molten salt. The molten salt medium can form a eutectic mixture, reduce the melting point of the molten salt system, improve the fluidity, and optimize the reaction environment. Preferably, the molar ratio of NaCl to KCl in the NaCl-KCl composite molten salt is 1:0.8-1.0, and the mass ratio of the iron-manganese slag to the NaCl-KCl composite molten salt is 1:2-5.

[0029] Step two, chlorination volatilization: the mixture is heated at a rate of 5-10℃ / min to 600-850℃ for 1-3h to perform the chlorination reaction. The chlorination reaction temperature must be higher than the formation reaction temperature of each metal chloride and ensure that it has sufficient vapor pressure to be volatilized. If the temperature is too low, the volatilization rate is low; if the temperature is too high, the energy consumption increases and the equipment may be corroded. After sufficient chlorination, volatilized substances and chlorination residues are obtained, and the waste gas generated during the reaction can be absorbed by lye, and the molten salt medium can be recycled.

[0030] Step three, gradient condensation separation: the volatilized substances are passed into a multi-stage condensation system, the first stage condensation section is controlled at a temperature of 650-750℃, and the MnCl2-rich manganese concentrate is recovered by condensation; the second stage condensation section is controlled at a temperature of 750-850℃, and the FeCl2 / FeCl3-rich iron concentrate is recovered by condensation. The temperature of the first condensation section is set as the best condensation interval based on the high-temperature volatilization of MnCl2, which can effectively capture it, while avoiding the solidification of FeCl2 / FeCl3 at this temperature interval; the temperature of the second condensation section aims to efficiently recover the iron component. Therefore, preferably, the temperature of the first stage condensation section is preferably 700±20℃, and the temperature of the second stage condensation section is preferably 800±20℃. In addition, a third condensation section can be provided after the second condensation section to collect volatile impurities at room temperature.

[0031] Step four, slag phase treatment: the chlorination residue is subjected to solvent leaching, and the scandium-containing leaching solution is obtained after solid-liquid separation; the scandium-containing leaching solution is subjected to solvent extraction to obtain a scandium-rich substance. The solid-liquid ratio of the chlorination residue to the solvent in the solvent leaching is 1g:4-10mL, the solvent is water or a hydrochloric acid solution with a concentration of 0.5-2.0mol / L, the leaching time is 70-90min, and the leaching temperature is 25-50℃. The solvent extraction is carried out with the scandium-containing leaching solution as the aqueous phase and an organic phase containing an extractant P204, a synergist TBP and a diluent. The extraction time is 1-10min, and the phase ratio O / A is 1 / 1-1 / 5; wherein, based on the total volume of the organic phase, the concentration of P204 is 5-20vol.%, the concentration of TBP is 5-20vol.%, and the balance is the diluent. Preferably, the diluent is any one of sulfonated kerosene, n-heptane, toluene, xylene and isoamyl alcohol.

[0032] The following specific examples will be listed to explain the scheme of the present application. Those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0033] In this embodiment, industrial-grade chlorine gas (purity ≥ 99.5%) is selected as the chlorinating agent, and NaCl-KCl composite molten salt (molar ratio of NaCl:KCl = 1:1) is selected as the molten salt medium; the main chemical components of the iron-manganese slag are as follows: Fe 23.8%, Mn 3.46%, Mg 4.05%, Ca 1.73%, Al 0.27%, Ti 0.52%, and Sc 0.013%.

[0034] The specific steps for separating and recovering scandium, manganese and iron from the iron-manganese slag are as follows: the iron-manganese slag is ground by a ball mill to 150 mesh, 500 g of the ground iron-manganese slag is mixed with 1 kg of NaCl-KCl composite molten salt, and then the mixture is loaded into a corundum crucible. The corundum crucible is placed in a tube furnace, and the temperature is raised to 700°C at a rate of 5°C / min. Chlorine gas is continuously introduced at a flow rate of 200 mL / min for 2 h, and the reaction is kept for 2 h. Two-stage condensing devices are arranged at the outlet of the tube furnace. The temperature of the first-stage condensing device is 680°C, and the manganese concentrate mainly containing MnCl2 is recovered. The temperature of the second-stage condensing device is 800°C, and the iron concentrate mainly containing FeCl3 is recovered. After the chlorination residue is cooled, it is leached with deionized water at a solid-liquid ratio of 1:4 (kg / L), a leaching temperature of 50°C and a leaching time of 90 min. After solid-liquid separation, a scandium-containing leaching solution is obtained. The scandium-containing leaching solution is extracted with 10 vol.% P204+5 vol.% TBP+85 vol.% sulfonated kerosene for 3 min, and the phase ratio O / A is 1 / 1, to obtain a scandium-rich material.

[0035] In this embodiment, the manganese in the iron-manganese slag is recovered in the form of manganese concentrate, and the recovery rate is 91.2%. The purity of MnCl2 in the concentrate is 31.85%. The iron is recovered in the form of iron concentrate, and the recovery rate is 88.7%. The purity of FeCl3 in the concentrate is 99.1%. The scandium is enriched in the leaching residue, and the Sc content in the obtained scandium-rich material is increased to 0.153 wt.%, and the enrichment multiple is 11.8 times. It can be seen that the present application successfully realizes the transformation of scandium, manganese and iron from the coexisting waste slag which is difficult to handle into the enriched material which is easy to further process, and lays a foundation for subsequent low-cost and high-efficiency refining processes.

[0036] In this embodiment, anhydrous calcium chloride is selected as the chlorinating agent, and NaCl-KCl composite molten salt (molar ratio of NaCl:KCl = 1:1) is selected as the molten salt medium; the main chemical components of the iron-manganese slag are as follows: Fe 25.4%, Mn 4.58%, Mg 3.87%, Ca 1.65%, Al 0.31%, Ti 0.58%, and Sc 0.029%.

[0037] The separation and recovery of scandium, manganese, and iron from iron-manganese slag involves the following steps: The iron-manganese slag is pulverized to 200 mesh using a ball mill. 1 kg of the pulverized slag is mixed with 1.2 kg of anhydrous calcium chloride for 10 min, followed by the addition of 3 kg of NaCl-KCl composite molten salt to obtain a mixture. This mixture is placed in a resistance furnace and heated to 750℃ at a rate of 10℃ / min, maintaining this temperature for 3 h. A three-stage condensation device is installed at the furnace outlet. The first stage condensation device operates at 650℃ to recover manganese concentrates, primarily MnCl2; the second stage condensation device operates at 780℃ to recover iron concentrates, primarily FeCl3; and the third stage condensation device operates at room temperature to collect volatile impurities. After cooling, the chlorinated residue was leached with 0.5 mol / L hydrochloric acid at a solid-liquid ratio of 1:5 (kg / L), at a leaching temperature of 40℃, and for 80 min. After solid-liquid separation, a scandium-containing leachate was obtained. The scandium-containing leachate was extracted with 8 vol.% P2O4 + 7 vol.% TBP + 85 vol.% sulfonated kerosene for 5 min, with an O / A ratio of 1 / 3, to obtain a scandium-rich product.

[0038] In this embodiment, manganese in the iron-manganese slag is recovered as a manganese concentrate with a recovery rate of 89.5%, and the purity of MnCl2 in the concentrate is 98.2%; iron is recovered as an iron concentrate with a recovery rate of 85.3%, and the purity of Fe in the concentrate is 98.2%. 3+ The concentration accounted for 76%, and the purity of the enriched product based on total ferric chloride was 95.2%. Scandium was enriched in the leaching residue with a leaching rate of 94.2%, and the enrichment factor of Sc in the obtained scandium-rich product was 10.2 times.

[0039] Example 3: In this example, industrial-grade chlorine (purity ≥99.5%) and anhydrous calcium chloride were selected as chlorinating agents, with a molar ratio of chlorine to calcium chloride of 1:3; NaCl-KCl composite molten salt (molar ratio of NaCl:KCl=1:1) was used as the molten salt medium; the main chemical components of the iron-manganese slag were: Fe 23.8%, Mn 3.46%, Mg 4.05%, Ca 1.73%, Al 0.27%, Ti 0.52%, Sc 0.013%.

[0040] The specific steps for separating and recovering scandium, manganese and iron from the iron-manganese slag are as follows: the iron-manganese slag is ground by a ball mill to 100 mesh, 2 kg of the ground iron-manganese slag is mixed with 0.2 kg of anhydrous calcium chloride for 10 min, then 3 kg of NaCl-KCl composite molten salt is added to obtain a mixture. The mixture is placed in a corundum crucible, and then the corundum crucible is placed in a tube furnace, which is heated to 800℃ at a rate of 5℃ / min, and chlorine gas is continuously introduced (flow rate is 150 mL / min, and the introduction time is 1.5 h), and the reaction is kept for 1.5 h. A three-stage condensing device is arranged at the outlet of the tube furnace, the temperature of the first-stage condensing device is 660℃, and the manganese concentrate mainly containing MnCl2 is recovered; the temperature of the second-stage condensing device is 780℃, and the iron concentrate mainly containing FeCl3 is recovered; the temperature of the third-stage condensing device is room temperature, and volatile impurities are collected. After the chlorination residue is cooled, it is leached with hydrochloric acid with a concentration of 1.0 mol / L, the solid-liquid ratio is 1:6 (kg / L), the leaching temperature is 50℃, and the leaching time is 70 min, and after solid-liquid separation, a scandium-containing leaching solution is obtained; the scandium-containing leaching solution is extracted with 10 vol.% P204+5 vol.% TBP+85 vol.% sulfonated kerosene, the extraction time is 4 min, and the phase ratio O / A is 1 / 5, and a scandium-rich material is obtained.

[0041] In the example, the manganese in the iron-manganese slag is recovered in the form of manganese concentrate, the recovery rate is 97.8%; the iron is recovered in the form of FeCl2 / FeCl3 iron concentrate, the recovery rate is 91.4%; the scandium is enriched in the leaching residue, the leaching rate is 96.5%, and the scandium-rich material obtained has a scandium enrichment multiple of 13.5 times.

Claims

1. A process for separating and recovering scandium, manganese and iron from iron-manganese slag, characterized by, The method comprises the following steps: S1. crushing the iron-manganese slag, then mixing the iron-manganese slag with a chlorinating agent and a molten salt medium to obtain a mixture; S2. performing a chlorination reaction on the mixture at 600-850 DEG C to obtain volatilization and chlorination residue; S2-1. collecting manganese and iron enrichment materials from the volatilization through multi-stage condensation; S2-2. dissolving the chlorination residue in a solvent to obtain a scandium-containing leaching solution after solid-liquid separation; S3. extracting the scandium-containing leaching solution to obtain a scandium-rich material.

2. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S1, the iron-manganese slag is crushed to a particle size of 100-200 mesh.

3. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S1, the chlorinating agent is chlorine and / or calcium chloride, which at least satisfies one of the following conditions: the amount of the chlorine is 1.5-3.0 mol / kg of the iron-manganese slag; the amount of the calcium chloride is 8.0-15.0 mol / kg of the iron-manganese slag; the amount of the chlorine is 0.2-1.0 mol / kg of the iron-manganese slag, the amount of the calcium chloride is 0.5-3.0 mol / kg of the iron-manganese slag, and the molar ratio of the chlorine to the calcium chloride is 1:1-4.

4. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S1, the molten salt medium is a NaCl-KCl composite molten salt, the molar ratio of NaCl to KCl in the NaCl-KCl composite molten salt is 1:0.8-1.0, and the mass ratio of the iron-manganese slag to the NaCl-KCl composite molten salt is 1:3-5.

5. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S2, the chlorination reaction is heated at a rate of 5-10 DEG C / min to 600-850 DEG C and kept for 1-3 h.

6. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S2-1, the multi-stage condensation is as follows: In the first-stage condensation section, the temperature is controlled at 650-750 DEG C, and MnCl2-rich manganese enrichment material is recovered by condensation; In the second-stage condensation section, the temperature is controlled at 750-850 DEG C, and FeCl2 / FeCl3-rich iron enrichment material is recovered by condensation.

7. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 6, characterized in that: The temperature in the first-stage condensation section is controlled at 700±20 DEG C, and the temperature in the second-stage condensation section is controlled at 800±20 DEG C.

8. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S2-2, the solid-liquid ratio of the chlorination residue to the solvent in the solvent leaching is 1g:4-10 mL, the solvent is water or a hydrochloric acid solution with a concentration of 0.5-2.0 mol / L, the leaching time is 70-90 min, and the leaching temperature is 25-50 DEG C.

9. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 1, characterized in that: In step S3, the solvent extraction is performed with the scandium-containing leaching solution as an aqueous phase and an organic phase containing an extractant P204, a synergist TBP and a diluent; wherein, based on the total volume of the organic phase, the concentration of P204 is 5-20 vol.%, the concentration of TBP is 5-20 vol.%, and the rest is the diluent; the extraction time is 1-10 min, and the phase ratio O / A is 1 / 1-1 / 5.

10. The process for separating and recovering scandium, manganese and iron from ferromanganese slag according to claim 9, characterized in that: The diluent is any one of sulfonated kerosene, n-heptane, toluene, xylene and isoamyl alcohol.