Preparation method of scandium trichloride

Abstract

The invention belongs to the field of chemical engineering, and particularly relates to a preparation method of scandium trichloride, which comprises the following steps: a) mixing scandium-containing ferro-manganese slag with carbon, and preheating to obtain a preheated material; b) chlorinating the preheated material to obtain a chloride material; c) feeding the chloride material into a vacuum smelting furnace for low-temperature vacuum smelting, raising the smelting temperature after low-boiling-point components in the material in the furnace are completely volatilized, and collecting scandium trichloride volatilized from the smelting furnace by using an organic solvent to obtain a solution containing scandium trichloride; d) removing the organic solvent in the solution to obtain scandium trichloride. According to the method provided by the invention, the high-purity scandium trichloride can be produced by using the iron-manganese slag, the scandium resource in the iron-manganese slag can be efficiently recycled, and the method has good economic benefits and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, and in particular relates to a method for preparing scandium trichloride. Background Technology

[0002] Scandium is scarce in the Earth's crust and rarely exists in independent minerals. It is often found in association with other metallic elements, and currently, it is not possible to efficiently extract scandium oxide or its derivatives directly from scandium-bearing ores. Furthermore, its physicochemical properties are highly similar to those of other transition metals, especially rare earth elements, further increasing the difficulty of separation and purification.

[0003] Molten salt chlorination waste is generated during the process of preparing titanium tetrachloride from titanium-rich titanium materials using molten salt chlorination. This waste contains a certain amount of the valuable element scandium, primarily in the form of a soluble salt. However, some scandium remains in the water-quenched slag after the molten salt chlorination waste treatment process, resulting in iron-manganese slag with high iron and manganese content. Currently, the industrial production of titanium tetrachloride mainly employs two processes: molten salt chlorination and fluidized bed chlorination. Molten salt chlorination accounts for approximately 40% of global production. The fluidized bed chlorination process has high requirements for the quality of the titanium slag raw materials (Ca+Mg content must be below 1.0%) and produces relatively less pollution. While molten salt chlorination can treat titanium slag with high calcium and magnesium content, it causes greater environmental pollution, and there is currently no economically feasible treatment technology for the resulting molten salt chlorination waste.

[0004] Currently, molten salt chlorination waste is generally disposed of by neutralizing it with lime and then storing it in wasteland or landfilling it, resulting in the failure to recover valuable scandium resources. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing scandium trichloride, which can utilize iron-manganese slag to produce high-purity scandium trichloride, thereby achieving efficient recovery of scandium resources from iron-manganese slag.

[0006] This invention provides a method for preparing scandium trichloride, comprising the following steps:

[0007] a) Mix scandium-containing iron-manganese slag with carbon, preheat, and obtain preheated material;

[0008] b) Chlorinate the preheated material to obtain a chlorinated material;

[0009] In step b), the chlorination temperature is 500~900℃; the chlorination time is 2~4h.

[0010] c) The chlorinated material is fed into a vacuum smelting furnace for low-temperature vacuum smelting. After the low-boiling components in the material in the furnace have completely volatilized, the smelting temperature is increased, and the scandium trichloride volatilized from the smelting furnace is collected using an organic solvent to obtain a solution containing scandium trichloride.

[0011] In step c), the vacuum degree of the vacuum smelting furnace is 1~100 Pa; the temperature of the low-temperature vacuum smelting is 200~600℃; and the temperature after the smelting temperature is increased is 700~900℃.

[0012] d) Remove the organic solvent from the solution to obtain scandium trichloride.

[0013] Preferably, in step a), the carbon is coke and / or graphite.

[0014] Preferably, in step a), the carbon accounts for 3 to 20 wt% of the total mass of the iron-manganese slag and carbon.

[0015] Preferably, in step a), the preheating temperature is 200~400℃; and the preheating time is 1~2h.

[0016] Preferably, in step b), the chlorinating agent used for chlorination is one or more of chloride salts, chlorine gas, and hydrogen chloride.

[0017] Preferably, the chloride salt is one or more of calcium chloride, sodium chloride, magnesium chloride, and ammonium chloride.

[0018] Preferably, in step c), the organic solvent is ethanol.

[0019] Preferably, in step d), the organic solvent is removed by vacuum rotary evaporation.

[0020] Preferably, the vacuum degree of the vacuum rotary evaporation is 70000~90000 Pa.

[0021] Preferably, in step a), the scandium content of the iron-manganese slag is 100~500ppm.

[0022] Compared with the prior art, the present invention provides a method for preparing scandium trichloride, comprising the following steps: a) mixing scandium-containing iron-manganese slag with carbon and preheating to obtain a preheated material; b) chlorinating the preheated material to obtain a chlorinated material; in step b), the chlorination temperature is 500~900℃; the chlorination time is 2~4h; c) sending the chlorinated material into a vacuum smelting furnace for low-temperature vacuum smelting, and after the low-boiling components in the material in the furnace have completely volatilized, raising the smelting temperature, and collecting the scandium trichloride volatilized from the smelting furnace using an organic solvent to obtain a solution containing scandium trichloride; in step c), the vacuum degree of the vacuum smelting furnace is 1~100Pa; the low-temperature vacuum smelting temperature is 200~600℃; the temperature after the smelting temperature is raised is 700~900℃; d) removing the organic solvent from the solution to obtain scandium trichloride. The method provided by this invention can produce high-purity scandium trichloride from iron-manganese slag, achieving efficient recovery of scandium resources from iron-manganese slag, and has good economic and environmental benefits. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a method for preparing scandium trichloride, comprising the following steps:

[0025] a) Mix scandium-containing iron-manganese slag with carbon, preheat, and obtain preheated material;

[0026] b) Chlorinate the preheated material to obtain a chlorinated material;

[0027] c) The chlorinated material is fed into a vacuum smelting furnace for low-temperature vacuum smelting. After the low-boiling components in the material in the furnace have completely volatilized, the smelting temperature is increased, and the scandium trichloride volatilized from the smelting furnace is collected using an organic solvent to obtain a solution containing scandium trichloride.

[0028] d) Remove the organic solvent from the solution to obtain scandium trichloride.

[0029] In the preparation method provided by the present invention, in step a), the scandium-containing iron-manganese slag comes from the molten salt chlorination waste salt treatment process and is the water-quenched waste slag of molten salt chlorination waste salt.

[0030] In the preparation method provided by the present invention, in step a), the scandium (Sc) content of the scandium-containing iron-manganese slag is preferably 100~500ppm, specifically 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm, 400ppm, 450ppm or 500ppm.

[0031] In the preparation method provided by this invention, in step a), the scandium-containing iron-manganese slag typically contains elements such as Na, Mg, Al, Si, S, Cl, Ca, Ti, Cr, Mn, and Fe, in addition to Sc; wherein, the Na content is preferably 3-6 wt%, more preferably 4-5 wt%, specifically 4.28 wt% or 4.51 wt%; the Mg content is preferably 4-12 wt%, more preferably 6-9 wt%, specifically 6.56 wt% or 8.76 wt%; the Al content is preferably 0.1-0.5 wt%, more preferably 0.3-0.4 wt%, specifically 0.35 wt% or 0.36 wt%; the Si content is preferably 0.1-0.3 wt%, more preferably 0.15-0.25 wt%, specifically 0.19 wt% or 0.21 wt%; the S content is preferably 0.05-0.3 wt%, more preferably 0.1-0.2 wt%, specifically... The preferred content of the Cl is 0.13 wt% or 0.19 wt%; the preferred content of the Ca is 5-10 wt%, more preferably 7-8 wt%, specifically 7.35 wt% or 7.45 wt%; the preferred content of the Ca is 1.5-2.5 wt%, more preferably 2-2.3 wt%, specifically 2.15 wt% or 2.16 wt%; the preferred content of the Ti is 0.1-1 wt%, more preferably 0.2-0.5 wt%, specifically 0.28 wt% or 0.43 wt%; the preferred content of the Cr is 0.2-1 wt%, more preferably 0.5-0.8 wt%, specifically 0.61 wt% or 0.67 wt%; the preferred content of the Mn is 2-10 wt%, more preferably 4-8 wt%, specifically 4.65 wt% or 7.44 wt%; the preferred content of the Fe is 25-50 wt%, more preferably 30-45 wt%, specifically 30.35 wt% or 42.85 wt%.

[0032] In the preparation method provided by the present invention, in step a), the D50 particle size of the scandium-containing iron-manganese slag is preferably 20~80μm, specifically 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm or 80μm.

[0033] In the preparation method provided by the present invention, in step a), the carbon is preferably coke and / or graphite; the mass ratio of coke to graphite is preferably 1:(0.5~2), specifically 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.

[0034] In the preparation method provided by the present invention, in step a), the particle size of the carbon is preferably 0.5~2mm, specifically 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm.

[0035] In the preparation method provided by the present invention, in step a), the carbon preferably accounts for 3 to 20 wt% of the total mass of iron-manganese slag and carbon, specifically 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%.

[0036] In the preparation method provided by the present invention, in step a), the purpose of mixing scandium-containing iron-manganese slag with carbon is to dissociate the scandium element dissolved in the iron-manganese slag.

[0037] In the preparation method provided by the present invention, in step a), the preheating temperature is preferably 200~400℃, specifically 200℃, 230℃, 250℃, 270℃, 300℃, 320℃, 350℃, 370℃ or 400℃; the preheating time is preferably 1~2h, specifically 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h; the preheating equipment can be a rotary kiln or other atmospheric pressure heating equipment.

[0038] In the preparation method provided by the present invention, the purpose of preheating in step a) is mainly to remove free water and hydroxyl groups from the raw materials.

[0039] In the preparation method provided by the present invention, in step b), the chlorinating reagent used for chlorination is preferably one or more of chloride salts, chlorine gas, and hydrogen chloride; the chloride salt is preferably one or more of calcium chloride, sodium chloride, magnesium chloride, and ammonium chloride. In some embodiments provided by the present invention, the chlorinating reagent is sodium chloride and ammonium chloride, and the molar ratio of sodium chloride to ammonium chloride is preferably 1:(0.5~2), specifically 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2; the total molar amount of sodium chloride and ammonium chloride to the molar ratio of the preheated material is preferably ≥2:5, specifically 2:1, 2:2, 2:3, 2:4, or 2:5. In some embodiments provided by the present invention, the chlorination reagent is chlorine gas and hydrogen chloride, and the molar ratio of chlorine gas to hydrogen chloride is preferably 1:(0.5~2), specifically 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.

[0040] In the preparation method provided by the present invention, in step b), the chlorination temperature is preferably 500~900℃, specifically 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃; the chlorination pressure is preferably atmospheric pressure; the chlorination time is preferably 2~4h, specifically 2h, 2.5h, 3h, 3.5h or 4h.

[0041] In the preparation method provided by the present invention, in step c), the vacuum degree of the vacuum smelting furnace is 1~100 Pa, specifically 1 Pa, 5 Pa, 10 Pa, 20 Pa, 30 Pa, 40 Pa, 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa or 100 Pa; the vacuum smelting furnace can be a vacuum induction melting furnace, a vacuum arc melting furnace, or a vacuum electron beam melting furnace, but is not limited to these three types of vacuum furnaces.

[0042] In the preparation method provided by the present invention, in step c), the temperature of the low-temperature vacuum smelting is preferably 200~600℃, specifically 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃.

[0043] In the preparation method provided by the present invention, in step c), low-temperature vacuum smelting is carried out under specific temperature and vacuum conditions, which can volatilize impurities such as ferric chloride and low-melting-point substances in the furnace material.

[0044] In the preparation method provided by the present invention, in step c), the temperature after the smelting temperature is increased is 700~900℃, specifically 700℃, 720℃, 750℃, 770℃, 800℃, 820℃, 850℃, 870℃ or 900℃.

[0045] In the preparation method provided by the present invention, in step c), the organic solvent is a solvent for dissolving scandium trichloride, preferably ethanol.

[0046] In the preparation method provided by the present invention, in step d), the organic solvent is preferably removed by vacuum rotary evaporation; the vacuum degree of the vacuum rotary evaporation is preferably 70000~90000 Pa, specifically 70000 Pa, 72000 Pa, 75000 Pa, 77000 Pa, 80000 Pa, 82000 Pa, 85000 Pa, 87000 Pa or 90000 Pa.

[0047] The method provided by this invention can produce high-purity scandium trichloride from iron-manganese slag, achieving efficient recovery of scandium resources from iron-manganese slag, and has good economic and environmental benefits.

[0048] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0049] Example 1

[0050] The scandium content in the treated molten salt chlorination waste salt residue (iron-manganese slag) was 100 ppm. Other components of the iron-manganese slag are shown in Table 1.

[0051] Table 1. Composition of iron-manganese slag in Example 1

[0052]

[0053] The first step involves mixing iron-manganese slag (D50=50μm) with coke (particle size 1mm), with the amount of coke accounting for 3wt% of the total material mass. The purpose is to dissociate the scandium element dissolved in iron oxide.

[0054] The second step is to preheat the mixture from the first step at a temperature of 200°C for 2 hours. The purpose of preheating is to remove free water and hydroxyl groups from the raw materials. The preheating equipment is a rotary kiln.

[0055] The third step involves mixing the preheated material with sodium chloride and ammonium chloride at a mass ratio of 5:1:1 and chlorinating it for 4 hours at atmospheric pressure and 500°C.

[0056] The fourth step involves calcining the material processed in the third step using a vacuum smelting furnace. The vacuum level is controlled at 1 Pa, and the temperature is controlled at 200°C within this vacuum range. This process can volatilize impurities such as ferric chloride, chlorides, and low-melting-point substances.

[0057] Fifth, after the impurities such as ferric chloride in the low-temperature section have completely evaporated, keep the vacuum level constant and raise the temperature to 700℃. Then, connect anhydrous ethanol to the dust collection port to collect relatively pure scandium trichloride.

[0058] The sixth step involves evaporating the organic solvent using a vacuum rotary evaporator. The vacuum level is reduced to 70,000 Pa, and anhydrous scandium trichloride with a purity of 99.99% is obtained at the bottom of the rotary evaporator.

[0059] Example 2

[0060] The scandium content in the treated molten salt chlorination waste salt residue (iron-manganese slag) is 500 ppm. Other components of the iron-manganese slag are shown in Table 2.

[0061] Table 2. Composition of iron-manganese slag in Example 2

[0062]

[0063] The first step involves mixing iron-manganese slag (D50=50μm) with coke (particle size 1mm) and graphite (particle size 1mm). The mass ratio of coke to graphite is 1:1, and the total amount of coke and graphite used accounts for 20wt% of the total material mass. The purpose is to dissociate the scandium element dissolved in iron oxide.

[0064] The second step is to preheat the mixture from the first step at a temperature of 400°C for 1 hour. The purpose of preheating is to remove free water and hydroxyl groups from the raw materials. The preheating equipment is a rotary kiln.

[0065] The third step involves directly introducing the preheated material into a mixed atmosphere of chlorine and hydrogen chloride, with a molar ratio of chlorine to hydrogen chloride of 1:1, and chlorinating for 2 hours at atmospheric pressure and 900°C.

[0066] The fourth step involves using a vacuum smelting furnace to process the material from the third step under a vacuum controlled at 100 Pa. This vacuum environment lowers the volatilization temperature of scandium chloride and ferric chloride. Within this vacuum range, the temperature is controlled at 600℃. This process effectively volatilizes impurities such as ferric chloride and low-melting-point substances.

[0067] Fifth, after the impurities such as ferric chloride in the low-temperature section have completely evaporated, keep the vacuum level constant and raise the temperature to 900℃. Then, connect anhydrous ethanol to the dust collection port to collect relatively pure scandium trichloride.

[0068] The sixth step involves evaporating the organic solvent using a vacuum rotary evaporator. The vacuum level is reduced to 90,000 Pa, and anhydrous scandium trichloride with a purity of 99.99% is obtained at the bottom of the rotary evaporator.

[0069] Comparative Example 1

[0070] The scandium content in the treated molten salt chlorination waste salt residue (iron-manganese slag) was 100 ppm. Other components of the iron-manganese slag are shown in Table 1.

[0071] The first step involves mixing iron-manganese slag (D50=50μm) with coke (particle size 1mm), with the amount of coke accounting for 3wt% of the total material mass. The purpose is to dissociate the scandium element dissolved in iron oxide.

[0072] The second step is to preheat the mixture from the first step at a temperature of 200°C for 2 hours. The purpose of preheating is to remove free water and hydroxyl groups from the raw materials. The preheating equipment is a rotary kiln.

[0073] The third step involves mixing the preheated material with sodium chloride and ammonium chloride at a mass ratio of 5:1:1 and chlorinating it for 3 hours at atmospheric pressure and 400°C.

[0074] The fourth step involves calcining the material processed in the third step using a vacuum smelting furnace. The vacuum level is controlled at 1 Pa, and the temperature is controlled at 200°C within this vacuum range. Due to the low temperature and short chlorination time in the third step, the main impurity element, ferric chloride, cannot be completely volatilized under the conditions of the fourth step, thus failing to obtain high-purity scandium chloride.

[0075] Comparative Example 2

[0076] The scandium content in the treated molten salt chlorination waste salt residue (iron-manganese slag) is 500 ppm. Other components of the iron-manganese slag are shown in Table 2.

[0077] The first step involves mixing iron-manganese slag (D50=50μm) with coke (particle size 1mm) and graphite (particle size 1mm). The mass ratio of coke to graphite is 1:1, and the total amount of coke and graphite used accounts for 20wt% of the total material mass. The purpose is to dissociate the scandium element dissolved in iron oxide.

[0078] The second step is to preheat the mixture from the first step at a temperature of 400°C for 1 hour. The purpose of preheating is to remove free water and hydroxyl groups from the raw materials. The preheating equipment is a rotary kiln.

[0079] The third step involves directly introducing the preheated material into a mixed atmosphere of chlorine and hydrogen chloride, with a molar ratio of chlorine to hydrogen chloride of 1:1, and chlorinating for 2 hours at atmospheric pressure and 900°C.

[0080] The fourth step involves using a vacuum smelting furnace to process the material from the third step, maintaining a vacuum level of 100 Pa. This vacuum environment helps lower the volatilization temperature of scandium chloride and ferric chloride. Within this vacuum range, the temperature is controlled at 700℃. However, due to the excessively high temperature, scandium trichloride is also drawn into the dust during the impurity removal process, making it impossible to collect in subsequent steps.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing scandium trichloride, characterized in that, Includes the following steps: a) Mix scandium-containing iron-manganese slag with carbon, preheat, and obtain preheated material; b) Chlorinate the preheated material to obtain a chlorinated material; In step b), the chlorination temperature is 500~900℃; the chlorination time is 2~4h. c) The chlorinated material is fed into a vacuum smelting furnace for low-temperature vacuum smelting. After the low-boiling components in the material in the furnace have completely volatilized, the smelting temperature is increased, and the scandium trichloride volatilized from the smelting furnace is collected using an organic solvent to obtain a solution containing scandium trichloride. In step c), the vacuum degree of the vacuum smelting furnace is 1~100 Pa; the temperature of the low-temperature vacuum smelting is 200~600℃; and the temperature after the smelting temperature is increased is 700~900℃. d) Remove the organic solvent from the solution to obtain scandium trichloride.

2. The preparation method according to claim 1, characterized in that, In step a), the carbon is coke and / or graphite.

3. The preparation method according to claim 1, characterized in that, In step a), the carbon accounts for 3 to 20 wt% of the total mass of the iron-manganese slag and carbon.

4. The preparation method according to claim 1, characterized in that, In step a), the preheating temperature is 200~400℃; the preheating time is 1~2h.

5. The preparation method according to claim 1, characterized in that, In step b), the chlorination reagent used is one or more of chloride salts, chlorine gas, and hydrogen chloride.

6. The preparation method according to claim 5, characterized in that, The chloride salt is one or more of calcium chloride, sodium chloride, magnesium chloride, and ammonium chloride.

7. The preparation method according to claim 1, characterized in that, In step c), the organic solvent is ethanol.

8. The preparation method according to claim 1, characterized in that, In step d), the organic solvent is removed by vacuum rotary evaporation.

9. The preparation method according to claim 8, characterized in that, The vacuum degree of the vacuum rotary evaporation is 70,000~90,000 Pa.

10. The preparation method according to any one of claims 1 to 9, characterized in that, In step a), the scandium content of the iron-manganese slag is 100~500ppm.

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