CN117758083A

CN117758083A - Method for recycling scandium in scandium-containing waste residues generated by titanium extraction through chlorination

Info

Publication number: CN117758083A
Application number: CN202311637785.9A
Authority: CN
Inventors: 杨珍
Original assignee: Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
Current assignee: Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
Priority date: 2023-12-01
Filing date: 2023-12-01
Publication date: 2024-03-26

Abstract

The invention discloses a method for recycling scandium in scandium-containing waste residue generated by extracting titanium through chlorination, which comprises the steps of dissolving scandium-containing waste residue by adopting excessive acid, fully reducing target cations in filtrate by using a reducing agent, and precipitating scandium in the reduced filtrate; repeating the acid leaching-reduction-scandium precipitation process according to the scandium content of the scandium-rich material to obtain a final scandium-rich material; the final scandium-rich material is subjected to acid leaching, reduction, phosphate impurity removal, multi-stage countercurrent extraction by a composite extractant, multi-stage countercurrent back extraction by a sodium oxalate solution and the like, and the obtained scandium oxalate precipitate is subjected to countercurrent washing by oxalic acid and then is subjected to high-temperature roasting, so that scandium oxide with purity of more than or equal to 99.9% is finally obtained. The recycling method has the advantages of convenient operation, simple process flow, low production cost, good environmental protection benefit, easy realization of industrialization and high-efficiency recycling of valuable element scandium in scandium-containing waste residues generated by extracting titanium by a chlorination process.

Description

Method for recycling scandium in scandium-containing waste residues generated by titanium extraction through chlorination

Technical Field

The invention belongs to the technical field of valuable resource recovery, and particularly relates to a method for recovering scandium in scandium-containing waste residues generated by titanium extraction by chlorination.

Background

Scandium is a rare earth element, belongs to strategic resources, has abundant global scandium resources, reserves of about 200 ten thousand t, and reserves of scandium of about 65 ten thousand t in China, but more than 75% of scandium is associated with other minerals, and the factors of complex scandium element extraction process, low overall process recovery rate, high cost and the like are the main reasons for causing the high price of scandium products, and scandium is one of the most expensive metals in the world. The scandium ore resources in China are mainly distributed in bauxite, phosphorite ore (containing weathering leaching type phosphorite bed), vanadium titano-magnetite, tungsten ore, rare earth ore and other minerals, the current scandium extraction raw material is mainly derived from secondary resources such as waste liquid or solid waste generated in the comprehensive utilization process of the co-associated minerals, the secondary resources which can be used as scandium extraction raw material comprise uranium ore byproducts, tungsten smelting waste residues, hydrolysis acid waste liquid generated in the production of titanium white by a sulfuric acid method, chlorinated smoke dust generated in the extraction of titanium by boiling chlorination, titanium-containing blast furnace slag, red mud, ion adsorption type rare earth ore, dolomite oblate tailings and the like, and the physical and chemical differences, especially the chemical compositions and the solubility in different leaches of the scandium extraction raw material are large, so that the involved scandium extraction process is different; the traditional scandium element extraction process has the technical defects of complex process, difficult operation, lower recovery rate, high cost and the like.

Disclosure of Invention

In order to solve the bottleneck problem of the traditional scandium extraction process technology, the invention aims to provide the method for recycling scandium in scandium-containing waste residues generated in the titanium extraction process by the chlorination process, which has the advantages of convenient operation, simple process flow, high efficiency, low production cost, good environmental protection benefit, easy realization of industrialization and capability of efficiently recycling valuable element scandium in scandium-containing waste residues generated in the titanium extraction process by the chlorination process. The scandium extraction raw material is mainly scandium-containing waste residue generated in the titanium extraction process by a chlorination method.

In order to realize the invention, the invention provides a method for recycling scandium in scandium-containing waste residues generated by titanium extraction by chlorination, which comprises the following steps:

s1, fully dissolving scandium-containing waste residues with excessive acid, filtering to obtain filter residues and filtrate, and returning the filter residues to the dissolving process for continuous dissolution;

s2, fully reducing target cations in the filtrate by using a reducing agent, filtering to obtain reduced filtrate and residues, returning the residues to the reduction process for continuous use, precipitating scandium in the reduced filtrate by using a precipitating agent, and filtering to obtain a primary scandium-rich material;

s3, leaching scandium in the primary scandium-rich material by using an acid solution, filtering to obtain scandium-containing filtrate and leaching slag, returning the leaching slag to the acid solution scandium leaching process, fully reducing target cations in scandium-containing leaching solution by using a reducing agent, precipitating scandium ions in the leaching solution subjected to reduction treatment by using a precipitating agent, filtering to obtain filtrate and scandium-rich material, and repeating the acid leaching-reduction-scandium precipitation process according to the scandium content of the scandium-rich material, wherein the repetition number is more than or equal to 1, thereby obtaining the final scandium-rich material;

s4, leaching scandium in the final scandium-rich material by using an acid solution, filtering to obtain leaching residues and scandium-containing solution, returning the leaching residues to the leaching process to continuously leach, reducing target cations in the scandium-containing solution by using a reducing agent, filtering to obtain filter residues and reduced scandium-containing solution, returning the filter residues to the reduction process to continuously use, precipitating zirconium in the reduced scandium-containing solution by using a soluble phosphate, and filtering to obtain zirconium phosphate precipitate and impurity-removing solution;

s5, carrying out multistage countercurrent extraction on scandium ions in the impurity-removed liquid prepared in the step S4 by using a composite extractant to obtain a scandium loaded organic phase and a raffinate;

s6, carrying out multistage countercurrent elution S5 by using an acid solution to obtain residual metal impurities in a scandium-loaded organic phase;

and S7, carrying out multistage countercurrent back extraction on the scandium-loaded organic phase eluted in the step S6 by using a sodium oxalate solution, filtering an aqueous phase to obtain scandium oxalate precipitate, washing the scandium oxalate precipitate in countercurrent by oxalic acid, and roasting the scandium oxalate precipitate at a high temperature to obtain scandium oxide with the purity of more than or equal to 99.9%.

In the above technical scheme, in S1, further, scandium-containing waste residue is waste residue of which main components are iron, magnesium, manganese, aluminum and calcium hydroxide, scandium content is not less than 50g/t, acid used in leaching is sulfuric acid, hydrochloric acid or nitric acid, and liquid-solid ratio is acid solution volume ml: scandium-containing waste residue mass g=1 to 10:1, the concentration of hydrogen ions in the acid solution is more than or equal to 1mol/L, preferably 4-8 mol/L, the leaching temperature is more than or equal to 20 ℃, preferably 50-98 ℃, and the leaching time is more than or equal to 1h, preferably 3-6 h.

Further, in S2, the target cation to be reduced is ferric iron, the reducing agent is one of metal powder or metal scraps of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the dosage of the reducing agent is 0.2-20 g/L scandium-containing solution, and the temperature during reduction is more than or equal to 40 ℃, preferably 60-95 ℃; the precipitant is one or more of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide and ammonia water, and the pH of the precipitation end point is controlled to be 3-6.

Further, in S3, the acid solution is one of sulfuric acid, hydrochloric acid and nitric acid, the concentration of the acid solution is more than or equal to 1mol/L, preferably 2-7 mol/L, and the liquid-solid ratio during leaching is the volume of the acid solution: scandium-enriched filter residue mass (dry basis) =1 to 10:1 (ml: g); the target cation to be reduced is ferric iron, the reducing agent is one of metal powder or metal scraps of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the consumption of the reducing agent is 0.01-5 g/L.leaching solution, and the system temperature of the leaching solution is more than or equal to 40 ℃ during reduction, preferably 60-95 ℃; the precipitant is one or more than two of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide and ammonia water, and the pH of the precipitation end point is controlled to be 3-6; and stopping repeating the acid leaching-reduction-scandium precipitation process when the scandium content of the scandium-containing precipitate is more than or equal to 5%, so as to obtain the final scandium-rich material with higher scandium content.

Further, in S4, the acid solution is sulfuric acid, the acid concentration is more than or equal to 1mol/L, preferably 2-4 mol/L, and the liquid-solid ratio during leaching is the volume of the acid solution: final scandium-rich material (dry basis) =1 to 10:1 (ml: g); the target cation to be reduced is ferric iron, the reducing agent is one of metal powder or metal scraps of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the consumption of the reducing agent is 0.001-1 g/L scandium-containing solution, and the system temperature is more than or equal to 40 ℃ during reduction, preferably 60-95 ℃; the soluble phosphate for zirconium removal is sodium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate or potassium dihydrogen phosphate, and the addition amount of the soluble phosphate in each liter of scandium-containing leaching solution is 0.04-1.5 g, and the solution is prepared before the addition.

Further, in S5, the compound extractant includes the following components in percentage by volume: 5-30% of P204, 5-20% of TBP, 0-10% of P507 and 50-90% of 260# solvent oil or sulfonated kerosene; during extraction, the volume ratio of the composite extractant of the organic phase to the impurity removing liquid after the reduction of the aqueous phase is 0.5-20:1, and the extraction stage number is more than or equal to 1; the extraction temperature is more than or equal to 5 ℃, preferably 20-40 ℃; the extraction equipment is an extraction tank, a cyclone extractor or a microchannel extraction equipment.

Further, in S6, the acid solution is sulfuric acid or hydrochloric acid, the elution level is more than or equal to 1, the eluting impurity removal temperature is more than or equal to 5 ℃, and the preferential temperature is 20-40 ℃.

Further, in S7, the concentration of sodium oxalate is 1 to 5mol/L, and the volume ratio of the loaded organic phase to the sodium oxalate solution during back extraction is 1: 1-5, wherein the back extraction stage number is more than or equal to 1, and the preferred back extraction stage number is 3-6; the concentration of oxalic acid for washing is more than or equal to 0.1mol/L, preferably 0.3-1 mol/L, and the liquid-solid ratio during washing is the volume ml of oxalic acid solution: scandium oxalate (wet material) weight g=1-10:1, the countercurrent washing stage number is more than or equal to 3, preferably 4-10, the scandium oxalate after washing and filtering is roasted, the temperature is raised to 105-125 ℃ at the speed of 5-10 ℃/min during roasting, the sediment is dried until the water content is less than or equal to 3%, the temperature is continuously raised to more than or equal to 700 ℃ at the speed of 10-40 ℃/min, the temperature is kept for more than or equal to 3 hours, the roasting temperature is preferably 800-1000 ℃, and the heat-preserving time is preferably 5-8 hours.

Compared with the prior art, the invention has the beneficial effects that:

according to the method, the scandium-containing waste residue is dissolved by using excessive acid, target cations in the filtrate are fully reduced by using a reducing agent, and scandium in the reduced filtrate is precipitated; repeating the acid leaching-reduction-scandium precipitation process according to the scandium content of the scandium-rich material to obtain a final scandium-rich material; the final scandium-rich material is subjected to acid leaching, reduction, phosphate impurity removal, multi-stage countercurrent extraction by a composite extractant, multi-stage countercurrent back extraction by a sodium oxalate solution and the like, and the obtained scandium oxalate precipitate is subjected to countercurrent washing by oxalic acid and then is subjected to high-temperature roasting, so that scandium oxide with purity of more than or equal to 99.9% is finally obtained. The method has the advantages of convenient operation, simple process flow, low production cost, good environmental protection benefit, easy realization of industrialization and high-efficiency recovery of valuable element scandium in scandium-containing waste residue generated by extracting titanium by a chlorination process.

Detailed Description

The invention is further illustrated below in connection with specific examples, but is not limited in any way. For the sake of brevity, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified. Unless specifically indicated otherwise, the processing conditions, the operation steps, the equipment used, and the like, which are specifically referred to in the present invention, are all known to those skilled in the art on the basis of the prior art without any inventive work.

A method for recycling scandium in scandium-containing waste residues generated by titanium extraction by chlorination comprises the following steps:

s1, fully dissolving scandium-containing waste residues by using excessive hydrochloric acid, filtering to obtain filter residues and filtrate, and returning the filter residues to the dissolving process for continuous dissolution;

s3, leaching scandium in the primary scandium-rich material by using an acid solution, filtering to obtain scandium-containing filtrate and leaching residues, returning the leaching residues to the acid solution scandium leaching process, fully reducing target cations in scandium-containing leaching solution by using a reducing agent, precipitating scandium ions in the leaching solution subjected to reduction treatment by using a precipitating agent, filtering to obtain filtrate and scandium-rich material, and repeating the acid leaching-reduction-scandium precipitation process according to scandium content of the scandium-rich material, wherein the repetition number is more than or equal to 1, thereby obtaining the final scandium-rich material;

s4, leaching scandium in the final scandium-rich material by using an acid solution, filtering to obtain leaching residues and scandium-containing solution, returning the leaching residues to the leaching process to continuously leach, reducing target cations in the scandium-containing solution by using a reducing agent, filtering to obtain filter residues and reduced scandium-containing solution, returning the filter residues to the reduction process to continuously use, precipitating zirconium in the reduced scandium-containing solution by using phosphate, and filtering to obtain zirconium phosphate precipitate and impurity-removing solution;

Examples

Scandium-containing waste residue obtained by sampling for a certain time has main components shown in table 1.

TABLE 1 scandium-containing waste residue composition table

S1, fully dissolving scandium-containing waste residue with scandium content of 0.029% by using 4mol/L hydrochloric acid solution, wherein the scandium-containing waste residue is mainly waste residue of iron, magnesium, manganese, aluminum and calcium hydroxide generated in the comprehensive utilization process of molten salt chloride waste salt, and the liquid-solid ratio is that the volume ml of acid solution: scandium-containing waste residue mass g=2: 1, the leaching temperature is 95 ℃, the leaching time is 6 hours, the leaching process is enhanced and stirred until no solid is deposited at the bottom of the reactor, filter residues and filtrate are obtained after filtration, the filter residues are returned to the dissolving process for continuous dissolution, the scandium leaching rate in the process is 97.9%, the Mg, fe, mn, al, cr, ca leaching rates are all about 80-90%, the V, ti and Si leaching rates are all about 40-60%, and the Zr leaching rate is less than or equal to 5%.

S2, fully reducing ferric ions in the obtained solution by using reduced iron powder, wherein the consumption of the reduced iron powder is 10 g/L.filtrate, the temperature is 60 ℃ during reduction, the reduction process is enhanced and stirred until no solid is deposited at the bottom of the reactor, after the reduction is completed, the filtrate and residues are obtained after the reduction by filtration, and the residues are returned to the reduction process for continuous use; the pH value is continuously regulated to 4.9 by using NaOH solution with the mass concentration of 10%, the process is enhanced to be stirred until no solid is deposited at the bottom of the reactor, the system temperature is 50 ℃, the primary scandium-rich material is obtained after filtration, the scandium precipitation rate in the process is 99.96%, and the precipitation rate of Mg, fe, mn, ca, zr, V, ti, si, al, cr is 0.02%, 0.6%, 0.02%, 0.05%, 11.51%, 8.62%, 8.97%, 12.63%, 99.89% and 99.57% respectively.

S3, dissolving the primary scandium-rich material by using a 4mol/L hydrochloric acid solution, wherein the liquid-solid ratio is the volume of the hydrochloric acid solution: scandium precipitate mass (water content 50%) =2: 1, fully reducing ferric ions in the obtained solution by using reduced iron powder, wherein the dosage of the reduced iron powder is 0.3 g/L.solution, filtering to obtain filtrate and residues after the reduction is completed, returning the residues to the reduction process, regulating the pH value of the filtrate to 4.0 by using 10% NaOH solution, filtering to obtain residual liquid and scandium-rich material, repeating the acid leaching-reduction-scandium precipitation process according to scandium enrichment condition of the scandium-rich material for 4 times, stopping repeating the acid leaching-reduction-scandium precipitation process, and finally obtaining the final scandium-rich material, wherein the scandium recovery rate in the process is 99.25%.

S4, dissolving the final scandium-rich material by using a sulfuric acid solution with the concentration of 3mol/L, wherein the liquid-solid ratio is that the volume ml of the sulfuric acid solution is: final scandium-rich mass g (water content 50%) =2: 1, scandium leaching rate is 99.99%, ferric ions in the obtained solution are fully reduced by using reduced iron powder, the consumption of the reduced iron powder is 0.2 g/L.solution, after the reduction is completed, filter residues and scandium-containing solution after the reduction are obtained by filtering, and the filter residues are returned to the reduction process for continuous use; adding sodium dihydrogen phosphate solution into scandium-containing solution after reduction to remove zirconium, wherein the adding amount of sodium dihydrogen phosphate is 0.7g, preparing the sodium dihydrogen phosphate solution into solution before adding, and filtering to obtain zirconium phosphate precipitation and impurity removing solution, wherein the zirconium precipitation rate is 99.86% and the scandium precipitation rate is less than 0.01%.

S5, performing multistage countercurrent extraction on scandium ions in the impurity-removed solution S4 by using a composite extractant, wherein the composite extractant comprises the following components in percentage by volume: 10% P204, 5% TBP, 2% P507, and 83% sulfonated kerosene; during extraction, the volume ratio of the organic phase composite extractant to the impurity removing liquid after aqueous phase reduction is 1:1, the extraction stage number is 2, the extraction temperature is 20 ℃, the single-stage extraction time is 6min, the phase separation time is 2min, the rotational flow extractor of the extraction equipment is 5min, the phase separation time of the organic phase and the aqueous phase is 5min, scandium-loaded organic phase and raffinate are obtained after phase separation, the scandium extraction rate in the process is 99.99%, and the extraction rate of other impurity elements is less than 0.01%.

S6, eluting S5 by using a sulfuric acid-hydrogen peroxide composite acid solution to obtain residual metal impurities such as iron, magnesium, calcium, manganese, titanium, zirconium and the like in the scandium-loaded organic phase, wherein the concentration of sulfuric acid is 25%, the concentration of hydrogen peroxide is 0.5mol/L, and the volume ratio of the loaded organic phase to the water phase is 1:1, countercurrent eluting with impurity removal stage number of 3, eluting at 30deg.C for 10min and phase separation for 1min, wherein scandium recovery rate in the process is 99.97%, and impurity element removal rate is more than 95%.

S7, carrying out multistage countercurrent back extraction on the eluted scandium loaded organic phase by using sodium oxalate with the mass concentration of 1mol/L, wherein the volume ratio of the loaded organic phase to the sodium oxalate solution is 1:1.5, the back extraction stage number is 2, the phase separation time is 5min, the back extraction temperature is 30 ℃, scandium oxalate is obtained after phase separation filtration, the scandium oxalate back extraction rate is 99.6%, the scandium oxalate is washed by adopting an oxalic acid solution with the concentration of 0.5mol/L, and the liquid-solid ratio is the volume ml of the oxalic acid solution during washing: and (3) roasting scandium oxalate subjected to washing and filtering, wherein the weight g=1:1 of scandium oxalate (wet material), the temperature of the washed and filtered scandium oxalate is raised to 125 ℃ at the speed of 10 ℃/min during roasting, the water content of the precipitate is kept at 0.9%, the temperature is continuously raised to 800 ℃ at the speed of 30 ℃/min, the temperature is kept for 6 hours, and finally scandium oxide with the purity of more than or equal to 99.98% is obtained.

The invention is not a matter of the known technology.

Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. The method for recycling scandium in scandium-containing waste residues generated by titanium extraction by chlorination is characterized by comprising the following steps of:

2. The recovery method according to claim 1, wherein in S1, the scandium-containing waste residue is a waste residue whose main component is iron, magnesium, manganese, aluminum or calcium hydroxide, the scandium content is not less than 50g/t, the acid used in leaching is sulfuric acid, hydrochloric acid or nitric acid, and the liquid-solid ratio is the volume of the acid solution: scandium-containing waste residue mass=1 to 10:1, the concentration of hydrogen ions in the acid solution is more than or equal to 1mol/L, preferably 4-8 mol/L, the leaching temperature is more than or equal to 20 ℃, preferably 50-98 ℃, and the leaching time is more than or equal to 1h, preferably 3-6 h.

3. The recovery method according to claim 1, wherein in S2, the target cation to be reduced is ferric iron, the reducing agent is one of metal powder of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the amount of the reducing agent is 0.2-20 g/L of scandium-containing solution, and the temperature at the time of reduction is not less than 40 ℃, preferably 60-95 ℃; the precipitant is one or more of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide and ammonia water, and the pH of the precipitation end point is controlled to be 3-6.

4. The recovery method according to claim 1, wherein in S3, the acid solution is one of sulfuric acid, hydrochloric acid and nitric acid, the concentration of the acid solution is not less than 1mol/L, preferably 2-7 mol/L, and the liquid-solid ratio during leaching is the volume of the acid solution: scandium enrichment filter residue dry basis mass=1-10: 1, a step of; the target cation to be reduced is ferric iron, the reducing agent is one of metal powder of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the consumption of the reducing agent is 0.01-5 g/L.leaching solution, and the system temperature of the leaching solution is more than or equal to 40 ℃ during reduction, preferably 60-95 ℃; the precipitant is one or more than two of sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, calcium oxide, calcium hydroxide, magnesium oxide, magnesium hydroxide and ammonia water, and the pH of the precipitation end point is controlled to be 3-6; and stopping repeating the acid leaching-reduction-scandium precipitation process when the scandium content of the scandium-containing precipitate is more than or equal to 5%, so as to obtain the final scandium-rich material with higher scandium content.

5. The recovery method according to claim 1, wherein in S4, the acid solution is sulfuric acid, the acid concentration is not less than 1mol/L, preferably 2 to 4mol/L, and the liquid-solid ratio during leaching is the volume ml of the acid solution: dry basis final scandium-rich feed g=1 to 10:1, a step of; the target cation to be reduced is ferric iron, the reducing agent is one of metal powder of iron, magnesium, zinc or aluminum, sodium metabisulfite and sodium sulfate, the consumption of the reducing agent is 0.001-1 g/L scandium-containing solution, and the system temperature is more than or equal to 40 ℃ during reduction, preferably 60-95 ℃; the soluble phosphate for zirconium removal is sodium phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate or potassium dihydrogen phosphate, and the addition amount of the soluble phosphate in each liter of scandium-containing leaching solution is 0.04-1.5 g, and the solution is prepared before the addition.

6. The recovery method according to claim 1, wherein in S5, the composite extractant comprises the following components in volume percent: 5-30% of P204, 5-20% of TBP, 0-10% of P507 and 50-90% of 260# solvent oil or sulfonated kerosene; during extraction, the volume ratio of the composite extractant of the organic phase to the impurity removing liquid after the reduction of the aqueous phase is 0.5-20:1, and the extraction stage number is more than or equal to 1; the extraction temperature is more than or equal to 5 ℃, preferably 20-40 ℃; the extraction equipment is an extraction tank, a cyclone extractor or a microchannel extraction equipment.

7. The recovery method according to claim 1, wherein in S6, the acid solution is sulfuric acid or hydrochloric acid, the elution order is not less than 1, the elution impurity removal temperature is not less than 5 ℃, preferably 20 to 40 ℃.

8. The recovery method according to claim 1, wherein in S7, the concentration of sodium oxalate is 1 to 5mol/L, and the volume ratio of the loaded organic phase to the sodium oxalate solution during back extraction is 1: 1-5, wherein the back extraction stage number is more than or equal to 1, and the preferred back extraction stage number is 3-6; the concentration of the oxalic acid for washing is more than or equal to 0.1mol/L, preferably 0.3-1 mol/L, and the liquid-solid ratio during washing is the volume of the oxalic acid solution: scandium oxalate wet material weight=1-10:1, countercurrent washing stage number is more than or equal to 3, preferably 4-10, roasting treatment is carried out on scandium oxalate after washing and filtering, heating to 105-125 ℃ at a speed of 5-10 ℃/min during roasting, drying the precipitate until the water content is less than or equal to 3%, continuously heating to a temperature of more than or equal to 700 ℃ at a speed of 10-40 ℃/min, and preserving heat at the temperature for more than or equal to 3 hours, preferably at a roasting temperature of 800-1000 ℃, and preferably preserving heat for 5-8 hours.