Method for preparing liquid rich in scandium from iron-manganese slag

Abstract

The present application belongs to the field of solid waste resource utilization, and particularly relates to a method for preparing a liquid rich in scandium from iron-manganese slag, comprising the following steps: a) heating and dehydrating scandium-containing iron-manganese slag to obtain dehydrated iron-manganese slag; b) mixing the dehydrated iron-manganese slag, SiO2 and carbon powder, and balling to obtain pellets; c) smelting the pellets to obtain an upper slag layer and a lower molten iron; the slag layer is cooled after being discharged from the smelting equipment, and is crushed to obtain slag powder; d) mixing the slag powder with a sulfuric acid solution with a concentration of greater than or equal to 98 wt%, and roasting to obtain a slurry; e) mixing the slurry with water, and filtering to obtain a liquid rich in scandium. The method provided by the present application uses iron-manganese slag as a raw material, and enriches and recovers scandium elements therein, has a high recovery rate, and has good economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization, and in particular relates to a method for preparing scandium-rich solution from iron-manganese slag. 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 this invention is to provide a method for preparing scandium-rich solution from iron-manganese slag, which can realize the resource recovery of scandium element in iron-manganese slag.

[0006] This invention provides a method for preparing scandium-rich solution from iron-manganese slag, comprising the following steps:

[0007] a) Scandium-containing iron-manganese slag is heated and dehydrated to obtain dehydrated iron-manganese slag;

[0008] b) Mix the dehydrated iron-manganese slag, SiO2 and carbon powder, and pelletize them to obtain pellets;

[0009] In step b), the amount of SiO2 used is 15-35% of the mass of the dehydrated iron-manganese slag, and the amount of carbon powder used is 7-20% of the mass of the dehydrated iron-manganese slag.

[0010] c) The pellets are smelted to obtain an upper slag layer and a lower molten iron layer; the slag layer is cooled and crushed after being discharged from the smelting equipment to obtain slag powder;

[0011] d) The slag powder is mixed with a sulfuric acid solution with a concentration ≥98wt%, and then calcined to obtain a slurry;

[0012] e) Mix the slurry with water and filter to obtain a scandium-rich solution.

[0013] Preferably, in step a), the scandium content of the scandium-containing iron-manganese slag is 100~500ppm.

[0014] Preferably, in step a), the heating and dehydration temperature is 400~600℃; and the heating and dehydration time is 1~3h.

[0015] Preferably, in step b), the firing temperature of the pellets is 1000~1200℃; and the firing time of the pellets is 1~5h.

[0016] Preferably, in step b), the particle size of the pellets is 5~20mm.

[0017] Preferably, in step c), the melting temperature is 1400~1600℃; and the melting time is 1~3h.

[0018] Preferably, in step c), the particle size of the slag powder is less than 1 mm.

[0019] Preferably, in step d), the mass ratio of the slag powder to the sulfuric acid solution is 1:(0.5~2).

[0020] Preferably, in step d), the roasting temperature is 250~400℃; and the roasting time is 1~3h.

[0021] Preferably, in step e), the volume ratio of the slurry to water is 1:(1~15).

[0022] Compared with existing technologies, this invention provides a method for preparing scandium-rich liquid from iron-manganese slag, comprising the following steps: a) heating and dehydrating scandium-containing iron-manganese slag to obtain dehydrated iron-manganese slag; b) mixing the dehydrated iron-manganese slag, SiO2, and carbon powder, and pelletizing to obtain pellets; in step b), the amount of SiO2 is 15-35% of the mass of the dehydrated iron-manganese slag, and the amount of carbon powder is 7-20% of the mass of the dehydrated iron-manganese slag; c) smelting the pellets to obtain an upper slag layer and a lower molten iron layer; the slag layer is cooled and pulverized after being discharged from the smelting equipment to obtain slag powder; d) mixing the slag powder with a sulfuric acid solution with a concentration ≥98wt%, and calcining to obtain a slurry; e) mixing the slurry with water, filtering, and obtaining scandium-rich liquid. The method provided by this invention uses iron-manganese slag as raw material to enrich and recover scandium, achieving a high recovery rate and possessing 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-rich solution from iron-manganese slag, comprising the following steps:

[0025] a) Scandium-containing iron-manganese slag is heated and dehydrated to obtain dehydrated iron-manganese slag;

[0026] b) Mix the dehydrated iron-manganese slag, SiO2 and carbon powder, and pelletize them to obtain pellets;

[0027] c) The pellets are smelted to obtain an upper slag layer and a lower molten iron layer; the slag layer is cooled and crushed after being discharged from the smelting equipment to obtain slag powder;

[0028] d) The slag powder is mixed with a sulfuric acid solution with a concentration ≥98wt%, and then calcined to obtain a slurry;

[0029] e) Mix the slurry with water and filter to obtain a scandium-rich solution.

[0030] 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.

[0031] 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.

[0032] 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 content of Na is preferably 2-5 wt%, more preferably 3-4 wt%, specifically 3.29 wt% or 3.91 wt%; the content of Mg is preferably 5-15 wt%, more preferably 8-12 wt%, specifically 9.64 wt% or 10.12 wt%; the content of Al is preferably 0.1-1 wt%, more preferably 0.2-0.6 wt%, specifically 0.34 wt% or 0.56 wt%; the content of Si is preferably 0.1-0.5 wt%, more preferably 0.2-0.3 wt%, specifically 0.21 wt% or 0.22 wt%; the content of S is preferably 0.1-0.5 wt%, more preferably 0.15-0.25 wt%, specifically... The content of the following components can be 0.18 wt% or 0.21 wt%; the content of Cl is preferably 5-15 wt%, more preferably 7-10 wt%, specifically 7.35 wt% or 9.66 wt%; the content of Ca is preferably 2-8 wt%, more preferably 3-5 wt%, specifically 3.96 wt% or 4.02 wt%; the content of Ti is preferably 0.1-0.5 wt%, more preferably 0.3-0.4 wt%, specifically 0.31 wt% or 0.36 wt%; the content of Cr is preferably 0.2-1 wt%, more preferably 0.5-0.8 wt%, specifically 0.68 wt% or 0.69 wt%; the content of Mn is preferably 2-8 wt%, more preferably 5-6 wt%, specifically 5.42 wt% or 5.78 wt%; the content of Fe is preferably 25-50 wt%, more preferably 30-45 wt%, specifically 30.96 wt% or 43.3 wt%.

[0033] 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.

[0034] In the preparation method provided by the present invention, in step a), the heating and dehydration temperature is preferably 400~600℃, specifically 400℃, 420℃, 450℃, 470℃, 500℃, 520℃, 550℃, 570℃ or 600℃; the heating and dehydration time is preferably 1~3h, specifically 1h, 1.2h, 1.5h, 1.7h, 2h, 2.3h, 2.5h, 2.7h or 3h; the heating and dehydration equipment can be a rotary kiln or other atmospheric pressure heating equipment.

[0035] In the preparation method provided by the present invention, the purpose of heating and dehydration in step a) is mainly to remove free water and hydroxyl groups from the raw materials.

[0036] In the preparation method provided by the present invention, in step b), the particle size of the SiO2 is preferably 2-8 mm, specifically 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm or 8 mm; the amount of SiO2 used is 15-35% of the mass of the dehydrated iron-manganese slag, specifically 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%.

[0037] In the preparation method provided by the present invention, in step b), the particle size of the carbon powder 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; the amount of carbon powder used is 7~20% of the mass of the dehydrated iron-manganese slag, specifically 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0038] In the preparation method provided by this invention, step b) preferably includes the following steps: first, mixing the dehydrated iron-manganese slag, SiO2, carbon powder, binder, and water to form green pellets, and then firing them into mature pellets; wherein, the binder is preferably bentonite; the amount of binder is preferably 0.2~0.6 wt% of the total mass of the dehydrated iron-manganese slag, SiO2, and carbon powder, specifically 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, or 0.6 wt%; the amount of water is preferably... The total mass of the pellets and carbon powder is 5-7 wt%, specifically 5 wt%, 5.2 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.2 wt%, 6.5 wt%, 6.7 wt%, or 7 wt%; the firing temperature for pelletizing is preferably 1000-1200℃, specifically 1000℃, 1020℃, 1050℃, 1070℃, 1100℃, 1120℃, 1150℃, 1170℃, or 1200℃; the firing time for pelletizing is preferably 1-5 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours.

[0039] In the preparation method provided by the present invention, in step b), the particle size of the pellets is preferably 5-20 mm, specifically 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm.

[0040] In the preparation method provided by the present invention, in step c), the melting temperature is preferably 1400~1600℃, specifically 1400℃, 1420℃, 1450℃, 1470℃, 1500℃, 1520℃, 1550℃, 1570℃ or 1600℃; the melting time is preferably 1~3h, specifically 1h, 1.5h, 2h, 2.5h or 3h.

[0041] In the preparation method provided by the present invention, in step c), the smelting is preferably carried out in an electric furnace, with slag discharged from the upper slag outlet and molten iron discharged from the lower outlet, and continuous feeding and discharging.

[0042] In the preparation method provided by the present invention, in step c), the particle size of the slag powder is preferably less than 1 mm.

[0043] In the preparation method provided by the present invention, in step d), the mass ratio of the slag powder to the sulfuric acid solution 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.

[0044] In the preparation method provided by the present invention, in step d), the mixing temperature is preferably 10~40℃, specifically 10℃, 15℃, 20℃, 25℃ (room temperature), 30℃, 35℃ or 40℃.

[0045] In the preparation method provided by the present invention, in step d), the calcination temperature is preferably 250~400℃, specifically 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃ or 400℃; the calcination time is preferably 1~3h, specifically 1h, 1.5h, 2h, 2.5h or 3h.

[0046] In the preparation method provided by the present invention, in step e), the volume ratio of the slurry to water is preferably 1:(1~15), specifically 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15.

[0047] In the preparation method provided by the present invention, in step e), the scandium content of the scandium-rich solution is preferably 30~400ppm, specifically 30ppm, 50ppm, 70ppm, 100ppm, 120ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm or 400ppm.

[0048] In the preparation method provided by the present invention, it is preferable to further include: extracting and purifying scandium in the obtained scandium-rich solution.

[0049] The method provided by this invention uses iron-manganese slag as raw material to enrich and recover scandium, achieving a high recovery rate and providing good economic and environmental benefits.

[0050] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0051] Example 1

[0052] 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.

[0053] Table 1. Composition of iron-manganese slag in Example 1

[0054]

[0055] The first step is to perform low-temperature dehydration pretreatment on the iron-manganese slag (D50=50μm). The iron-manganese slag is placed in a rotary kiln at 400℃ for two hours to remove free water and hydroxyl groups.

[0056] The second step involves adding 15% SiO2 (5mm particle size) and 7% carbon powder (1mm particle size) by weight of the pretreated iron-manganese slag. After mixing evenly, 0.4wt% bentonite and 6wt% water by weight of the total mixture are added. The mixture is then made into green pellets in a pelletizing machine and fired at 1000℃ for 2 hours to obtain cooked pellets with a particle size of 5~20mm.

[0057] The third step is to place the fired pellets in an electric furnace at 1600℃ for 3 hours to melt them. Slag is discharged from the upper slag outlet and molten iron is discharged from the lower outlet, with continuous feeding and discharging.

[0058] The fourth step is to crush and grind the slag after it cools down, and control the particle size to be below 1 mm. The ground slag is then mixed with 98 wt% concentrated sulfuric acid at room temperature. The mass ratio of dry material to concentrated sulfuric acid is 1:0.5. After mixing evenly, the mixture is roasted at 400℃ for 3 hours.

[0059] The fifth step is to pour the roasted slurry into water at a volume ratio of 1:1. After filtering out the insoluble residue, a relatively pure scandium-rich aqueous solution with a scandium content of 30 ppm is obtained (this scandium-rich solution can be further extracted and purified).

[0060] Example 2

[0061] 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.

[0062] Table 2. Composition of iron-manganese slag in Example 2

[0063]

[0064] The first step is to perform low-temperature dehydration pretreatment on the iron-manganese slag (D50=50μm). The iron-manganese slag is placed in a rotary kiln at 600℃ for two hours to remove free water and hydroxyl groups.

[0065] The second step involves adding 35% SiO2 (5mm particle size) and 20% carbon powder (1mm particle size) by weight of the pretreated iron-manganese slag. After mixing evenly, 0.4wt% bentonite and 6wt% water by weight of the total mixture are added. The mixture is then made into green pellets in a pelletizing machine and fired at 1200℃ for 2 hours to obtain cooked pellets with a particle size of 5~20mm.

[0066] The third step is to place the fired pellets in an electric furnace at 1400℃ for 1 hour, discharge slag from the upper slag outlet and discharge molten iron from the lower outlet, and continuously feed and discharge the pellets.

[0067] The fourth step is to crush and grind the slag after it cools down, and control the particle size to be below 1 mm. The ground slag is then mixed with 98 wt% concentrated sulfuric acid at room temperature. The mass ratio of dry material to concentrated sulfuric acid is 1:2. After mixing evenly, the mixture is roasted at 250°C for 1 hour.

[0068] The fifth step is to pour the roasted slurry into water at a volume ratio of 1:3. After filtering out the insoluble residue, a relatively pure scandium-rich aqueous solution with a scandium content of 400 ppm is obtained (this scandium-rich solution can be further extracted and purified).

[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 is to perform low-temperature dehydration pretreatment on the iron-manganese slag (D50=50μm). The iron-manganese slag is placed in a rotary kiln at 400℃ for two hours to remove free water and hydroxyl groups.

[0072] The second step involves adding 7% SiO2 (5mm particle size) and 7% carbon powder (1mm particle size) by weight of the pretreated iron-manganese slag. After mixing evenly, 0.4wt% bentonite and 6wt% water by weight of the total mixture are added. The mixture is then made into green pellets in a pelletizing machine and fired at 1000℃ for 2 hours to obtain cooked pellets with a particle size of 5~20mm.

[0073] The third step involves placing the sintered pellets in an electric furnace at 1600℃ for 3 hours. Due to insufficient SiO2 addition, slag and iron cannot be separated, and scandium cannot be separated from the iron and manganese in the iron-manganese slag.

[0074] Comparative Example 2

[0075] 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.

[0076] The first step is to perform low-temperature dehydration pretreatment on the iron-manganese slag (D50=50μm). The iron-manganese slag is placed in a rotary kiln at 600℃ for two hours to remove free water and hydroxyl groups.

[0077] The second step involves adding 35% SiO2 (5mm particle size) and 20% carbon powder (1mm particle size) by weight of the pretreated iron-manganese slag. After mixing evenly, 0.4wt% bentonite and 6wt% water by weight of the total mixture are added. The mixture is then made into green pellets in a pelletizing machine and fired at 1200℃ for 2 hours to obtain cooked pellets with a particle size of 5~20mm.

[0078] The third step is to place the fired pellets in an electric furnace at 1400℃ for 1 hour, discharge slag from the upper slag outlet and discharge molten iron from the lower outlet, and continuously feed and discharge the pellets.

[0079] The fourth step involves cooling the slag layer and then crushing and grinding it to a particle size below 1 mm. The ground slag is then mixed with a 70 wt% sulfuric acid solution at room temperature, with a dry material to sulfuric acid solution mass ratio of 1:2. After thorough mixing, the mixture is roasted at 250°C for 1 hour. During the sulfurization roasting process, due to the high water content, soluble scandium sulfate cannot be formed, and the scandium remains in the roasting process and cannot be leached out with water.

[0080] 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-rich solution from iron-manganese slag, characterized in that, Includes the following steps: a) Scandium-containing iron-manganese slag is heated and dehydrated to obtain dehydrated iron-manganese slag; b) Mix the dehydrated iron-manganese slag, SiO2 and carbon powder, and pelletize them to obtain pellets; In step b), the amount of SiO2 used is 15-35% of the mass of the dehydrated iron-manganese slag, and the amount of carbon powder used is 7-20% of the mass of the dehydrated iron-manganese slag. c) The pellets are smelted to obtain an upper slag layer and a lower molten iron layer; the slag layer is cooled and crushed after being discharged from the smelting equipment to obtain slag powder; d) The slag powder is mixed with a sulfuric acid solution with a concentration ≥98wt%, and then calcined to obtain a slurry; e) Mix the slurry with water and filter to obtain a scandium-rich solution.

2. The method according to claim 1, characterized in that, In step a), the scandium content of the scandium-containing iron-manganese slag is 100~500ppm.

3. The method according to claim 1, characterized in that, In step a), the heating and dehydration temperature is 400~600℃; the heating and dehydration time is 1~3h.

4. The method according to claim 1, characterized in that, In step b), the firing temperature for pelletizing is 1000~1200℃; the firing time for pelletizing is 1~5h.

5. The method according to claim 1, characterized in that, In step b), the particle size of the pellets is 5~20mm.

6. The method according to claim 1, characterized in that, In step c), the melting temperature is 1400~1600℃; the melting time is 1~3h.

7. The method according to claim 1, characterized in that, In step c), the particle size of the slag powder is less than 1 mm.

8. The method according to claim 1, characterized in that, In step d), the mass ratio of the slag powder to the sulfuric acid solution is 1:(0.5~2).

9. The method according to claim 1, characterized in that, In step d), the roasting temperature is 250~400℃; the roasting time is 1~3h.

10. The method according to claim 1, characterized in that, In step e), the volume ratio of the slurry to water is 1:(1~15).

Images